Mitophagy Regulates Neurodegenerative Diseases: Comparison
Please note this is a comparison between Version 2 by Conner Chen and Version 1 by hongguang xia.

Mitochondria are the primary source of cellular energy regulating cellular metabolism and physiology. To maintain cellular metabolism and homeostasis, damaged or unwanted mitochondria should be eliminated through mitophagy, a form of mitochondrial quality control process. Mitophagy is a highly selective autophagy process that eliminates dysfunctional or redundant mitochondria through multiple regulatory pathways in a ubiquitin-dependent or -independent manner. Since the term “mitophagy” was first coined by Dr. Lemasters in 2005, accumulating scientific evidence reveals that the accumulation of damaged mitochondria is one of the causal factors for various human diseases including neurodegenerative and cardiovascular diseases as well as cancers. Among all the cell types affected by mitochondrial dysfunction, neurons are vulnerable to mitochondrial damage due to their high energy demand. 

  • mitophagy
  • neurodegenerative diseases
  • Parkinson’s disease
  • Alzheimer’s disease
  • Huntington’s disease

1. Aging

Mitochondria play an essential role in the process of aging. The function of mitochondria decreases, and mitochondrial DNA mutations accumulate with aging. In the process of aging, the feature of dysfunctional mitochondria includes decreasing the content of mitochondria, changing the morphology of mitochondria, reducing the efficiency of the electron transport chain, and increasing ROS production. The mitochondrial quality control system, especially mitophagy, decreases with the deepening of aging. These changes are accompanied by the occurrence and development of diseases. Due to the high energy consumption of neurons, mitochondria are particularly important for their function, indicating that aging is a significant risk factor for neurodegenerative diseases.

In recent studies, the induction of mitophagy and degeneration of NAD

+ in Werner syndrome (WS) patients, which is an autosomal recessive accelerated aging disease and caused by mutations in the gene encoding the Werner (WRN) DNA helicase, has been observed [67]. The main clinical symptoms include cancer, juvenile cataracts, dyslipidemia, premature atherosclerosis, and insulin resistance diabetes. NAD

 in Werner syndrome (WS) patients, which is an autosomal recessive accelerated aging disease and caused by mutations in the gene encoding the Werner (WRN) DNA helicase, has been observed [1]. The main clinical symptoms include cancer, juvenile cataracts, dyslipidemia, premature atherosclerosis, and insulin resistance diabetes. NAD

+ supplementation can significantly relieve the accelerated aging process in Caenorhabditis elegans and Drosophila melanogaster models of WS [67]. Through the mechanism study, the NAD

 supplementation can significantly relieve the accelerated aging process in Caenorhabditis elegans and Drosophila melanogaster models of WS [1]. Through the mechanism study, the NAD

+ effect is achieved through DCT-1 and ULK-1 dependent mitophagy [67]. Cardiovascular aging is another very important aging event in which the regulation of mitochondrial homeostasis is involved [68]. Many studies have shown that mitophagy plays an important role in the anti-cardiovascular aging process in recent years. Heat shock protein 27 (HSP27), a small heat shock protein involved in the responses to oxidative stress, heat shock, and hypoxic/ischemia injury [69], can induce mitophagy and antioxidant function to reduce the degree of heart aging [70]. Another study demonstrated that double knockout of Akt2 and AMPK induced cardiac aging in 12-month-old mice, which was most likely achieved by reducing autophagy and mitophagy levels because more p62, lower LC3B II and LC3B I ratios, and lower level of mitophagy receptors associated with aging including PINK1, Fundc1, etc. were observed in double knockout Akt2 and AMPK mice [71]. Harman’s free radical theory is the commonly accepted aging theory at present [72,73]. This theory assumes that the decrease in cellular longevity is caused by the increase in reactive oxygen species. Recent studies have shown that mitochondria are the main source of ROS and the main target of ROS-mediated damage [74]. ROS is a by-product of mitochondrial respiration. With aging, mitochondria function decreases, and more ROS are accumulated, leading to the damage of mitochondria and mtDNA. These phenomena suggest that increasing mitophagy and restoring mitochondrial function can prevent and treat vascular and cardiac aging-related dysfunction.

 effect is achieved through DCT-1 and ULK-1 dependent mitophagy [1]. Cardiovascular aging is another very important aging event in which the regulation of mitochondrial homeostasis is involved [2]. Many studies have shown that mitophagy plays an important role in the anti-cardiovascular aging process in recent years. Heat shock protein 27 (HSP27), a small heat shock protein involved in the responses to oxidative stress, heat shock, and hypoxic/ischemia injury [3], can induce mitophagy and antioxidant function to reduce the degree of heart aging [4]. Another study demonstrated that double knockout of Akt2 and AMPK induced cardiac aging in 12-month-old mice, which was most likely achieved by reducing autophagy and mitophagy levels because more p62, lower LC3B II and LC3B I ratios, and lower level of mitophagy receptors associated with aging including PINK1, Fundc1, etc. were observed in double knockout Akt2 and AMPK mice [5]. Harman’s free radical theory is the commonly accepted aging theory at present [6][7]. This theory assumes that the decrease in cellular longevity is caused by the increase in reactive oxygen species. Recent studies have shown that mitochondria are the main source of ROS and the main target of ROS-mediated damage [8]. ROS is a by-product of mitochondrial respiration. With aging, mitochondria function decreases, and more ROS are accumulated, leading to the damage of mitochondria and mtDNA. These phenomena suggest that increasing mitophagy and restoring mitochondrial function can prevent and treat vascular and cardiac aging-related dysfunction.

Although growing studies have shown that there is a strong relationship between mitophagy and aging, the reason for the decline in mitophagy with aging is not clear. With aging, ROS accumulation may lead to the oxidation of many proteins related to mitophagy function including PINK1, Parkin, LC3, etc. The oxidation of protein will reduce its function, which may lead to mitophagy dysfunction. S-nitrosylation is a critical post-translational regulation of most proteins, which attaches a nitrogen monoxide group to the thiol side chain of cysteine [75]. Recent studies have shown that it may play an important role in aging and neurodegenerative diseases [76]. S-nitrosoglutathione reductase (GSNOR) is an important enzyme regulating S-nitrosylation. Its activity gradually decreases with aging, and leads to mitophagy related protein such as Drp1 and Parkin S-nitrosylation, thus affecting the function of mitophagy [77]. Another study on Alzheimer’s disease (AD) revealed that the S-nitrosylation transfer reaction mediated by UCH-L1, Cdk5, and Drp1 may play an important role in the occurrence and development of AD [76]. These results indicate that with the development of aging, post-translational modification may play a critical role in the dysfunction of proteins, which affects the physiological process, especially mitophagy.

Although growing studies have shown that there is a strong relationship between mitophagy and aging, the reason for the decline in mitophagy with aging is not clear. With aging, ROS accumulation may lead to the oxidation of many proteins related to mitophagy function including PINK1, Parkin, LC3, etc. The oxidation of protein will reduce its function, which may lead to mitophagy dysfunction. S-nitrosylation is a critical post-translational regulation of most proteins, which attaches a nitrogen monoxide group to the thiol side chain of cysteine [9]. Recent studies have shown that it may play an important role in aging and neurodegenerative diseases [10]. S-nitrosoglutathione reductase (GSNOR) is an important enzyme regulating S-nitrosylation. Its activity gradually decreases with aging, and leads to mitophagy related protein such as Drp1 and Parkin S-nitrosylation, thus affecting the function of mitophagy [11]. Another study on Alzheimer’s disease (AD) revealed that the S-nitrosylation transfer reaction mediated by UCH-L1, Cdk5, and Drp1 may play an important role in the occurrence and development of AD [10]. These results indicate that with the development of aging, post-translational modification may play a critical role in the dysfunction of proteins, which affects the physiological process, especially mitophagy.

In addition, skeletal muscle aging is also related to mitophagy. Sarcopenia refers to the loss of muscle mass and function with aging, and its molecular mechanism is not clear. However, an increasing body of evidence has shown that it is related to decreased autophagy levels, especially mitophagy. Mitochondrial dysfunction and fragmentation exist in aging muscles, which indicates that the regulation of mitochondrial homeostasis is unbalanced. Some studies have reported that NIX, PINK1, and Parkin levels are enhanced in aging muscles, suggesting that mitophagy as an anti-aging process is activated with aging [78,79,80]. Although mitophagy can remove damaged mitochondria and restore mitochondria health, with the deepening of the aging process, the related functional proteins of mitophagy are oxidized, resulting in the weakening of function, which is not enough to clear the damaged mitochondria, thus accelerating the aging. Exercise is thought to be a way to enhance mitophagy. Studies have shown that Parkin plays an important role in exercise-induced mitophagy [79], suggesting that Parkin, as a regulatory protein of mitophagy, participates in the process of mitophagy in skeletal muscle and plays an critical role in the aging of skeletal muscle. These studies indicate that the induction of mitophagy has a significant effect on the treatment of aging-related diseases. A clinical trial on Urolithin A (UA) shows that UA, as a safe and effective inducer of mitophagy, plays an important role in skeletal muscle health, providing more evidence for the treatment of premature aging-related disease by the induction of mitophagy [81].

In addition, skeletal muscle aging is also related to mitophagy. Sarcopenia refers to the loss of muscle mass and function with aging, and its molecular mechanism is not clear. However, an increasing body of evidence has shown that it is related to decreased autophagy levels, especially mitophagy. Mitochondrial dysfunction and fragmentation exist in aging muscles, which indicates that the regulation of mitochondrial homeostasis is unbalanced. Some studies have reported that NIX, PINK1, and Parkin levels are enhanced in aging muscles, suggesting that mitophagy as an anti-aging process is activated with aging [12][13][14]. Although mitophagy can remove damaged mitochondria and restore mitochondria health, with the deepening of the aging process, the related functional proteins of mitophagy are oxidized, resulting in the weakening of function, which is not enough to clear the damaged mitochondria, thus accelerating the aging. Exercise is thought to be a way to enhance mitophagy. Studies have shown that Parkin plays an important role in exercise-induced mitophagy [13], suggesting that Parkin, as a regulatory protein of mitophagy, participates in the process of mitophagy in skeletal muscle and plays an critical role in the aging of skeletal muscle. These studies indicate that the induction of mitophagy has a significant effect on the treatment of aging-related diseases. A clinical trial on Urolithin A (UA) shows that UA, as a safe and effective inducer of mitophagy, plays an important role in skeletal muscle health, providing more evidence for the treatment of premature aging-related disease by the induction of mitophagy [15].

2. Parkinson’s Disease

Parkinson’s disease (PD) is a prevalent neurodegenerative disorder primarily characterized by loss of dopaminergic neurons in the substantia nigra and accumulation of mutational alpha-synuclein. This was first described by James Parkinson in 1917 [82]. The precise mechanism of PD is unclear, but considerable evidence suggests that damage in mtDNA, redundant ROS, and dysfunctional mitophagy potentially regulates the occurrence of PD [83,84]. Accumulation of mitochondrial DNA (mtDNA) mutations caused by reactive oxygen species (ROS) results in mitochondrial dysfunction, thereby enhancing ROS production [85]. Mitophagy, a crucial mitochondrial quality control process, regulates mitochondrial function for neuron health [86]. Accumulation of damaged and dysfunctional mitochondria has been observed in Parkinson’s disease, suggesting that mitochondrial network homeostasis is impaired in PD patients [87,88]. Furthermore, PINK1 knockout mice revealed a progressive loss of dopaminergic neurons in the substantia nigra [89]. This suggests that the disorder of the mitophagy process is potentially and strongly associated with PD (

Parkinson’s disease (PD) is a prevalent neurodegenerative disorder primarily characterized by loss of dopaminergic neurons in the substantia nigra and accumulation of mutational alpha-synuclein. This was first described by James Parkinson in 1917 [16]. The precise mechanism of PD is unclear, but considerable evidence suggests that damage in mtDNA, redundant ROS, and dysfunctional mitophagy potentially regulates the occurrence of PD [17][18]. Accumulation of mitochondrial DNA (mtDNA) mutations caused by reactive oxygen species (ROS) results in mitochondrial dysfunction, thereby enhancing ROS production [19]. Mitophagy, a crucial mitochondrial quality control process, regulates mitochondrial function for neuron health [20]. Accumulation of damaged and dysfunctional mitochondria has been observed in Parkinson’s disease, suggesting that mitochondrial network homeostasis is impaired in PD patients [21][22]. Furthermore, PINK1 knockout mice revealed a progressive loss of dopaminergic neurons in the substantia nigra [23]. This suggests that the disorder of the mitophagy process is potentially and strongly associated with PD (

Table 1

).

Table 1.

 Genes related to neurodegenerative diseases and mitophagy.

Gene Protein Function in Mitophagy Disease Reference
PARK6 PINK1 Kinase, involved in the regulation of several mitophagy related proteins PD, AD, HD [90,91][24][25]
PARK2 Parkin Selectively recognize and eliminate damaged mitochondria from the cell PD, AD, HD [91,92][25][26]
SNCA Alpha-synuclein Located on the mitochondria through its N-terminal, lead to mitochondrial damage and dysfunction PD [93][27]
DJ-1 Protein DJ-1 Regulate mitophagy and ATP produce PD [94][28]
GBA Glucocerebrosidase Ensure normal function of lysosome and influence mitochondrial morphology and dynamics PD [93,95][27][29]
DRP1 Dynamin-related protein 1 Mediate mitochondrial fission PD, AD, HD [96][30]
OPA1 Optic atrophy 1 Mediate mitochondrial fusion PD, AD, HD [97][31]
MFN1 Mitofusin 1 Mediate mitochondrial fusion PD, AD, HD [98][32]
VCP Valosin-containing protein Accumulation of VCP can induce superabundant mitophagy HD [99][33]
Rhes Ras homolog enriched in striatum Up-regulate mitophagy via NIX receptor HD [100][34]
OPTN Optineurin Mediates the formation of autophagosome ALS [101][35]
TBK1 TANK-binding kinase 1 Mediate the engulfment of damaged mitochondria ALS [102][36]
PINK1-Parkin pathway mutations inhibit mitophagy, which is directly related to PD occurrence [38]. PINK1 is highly expressed in organs or tissues with high energy demand including the brain, heart, and muscles. Moreover, Parkin is expressed in various types of tissues, which perhaps shows its complex functions [103]. Parkin mutations related to PD prevent the recruitment of Parkin to mitochondria and the accumulation of damaged mitochondria. This enhances ROS production, thereby promoting PD pathologies [92]. Moreover, mitochondrial disturbance of fission and fusion caused by alpha-synuclein can be rescued via PINK1 and Parkin co-expression [104]. Additionally, the NIX-mediated mitophagy pathway independently restores mitophagy in the PD patient cell lines without functional PINK1 and Parkin [105]. On the other hand, USP30 is identified as a deubiquitinase for mitophagy regulation negatively. Overexpression of USP30 inhibits mitophagy by removing ubiquitin on damaged mitochondria [106]. Several USP30 inhibitors are under development for the treatment of PD [107]. Despite PINK1/Parkin pathway dysfunction being a major contribution to PD pathologies, more studies have shown other genes that influence mitophagy involved in PD. DJ-1 is a mitochondrial location redox sensor. Loss of DJ-1 leads to mitochondrial fragmentation that may affect mitophagy. Mutation of DJ-1 causes a recessive form of PD [108,109]. Mutation of LRRK2, a large multidomain protein, influences mitophagy via regulating the PINK1/Parkin pathway, causing an autosomal dominant form of PD [110,111,112]. These findings suggest that mitochondrial dysfunction is strongly related to PD pathogenesis, and induction of mitophagy rescuing mitochondrial biogenesis may ameliorate PD pathology.

PINK1-Parkin pathway mutations inhibit mitophagy, which is directly related to PD occurrence [37]. PINK1 is highly expressed in organs or tissues with high energy demand including the brain, heart, and muscles. Moreover, Parkin is expressed in various types of tissues, which perhaps shows its complex functions [38]. Parkin mutations related to PD prevent the recruitment of Parkin to mitochondria and the accumulation of damaged mitochondria. This enhances ROS production, thereby promoting PD pathologies [26]. Moreover, mitochondrial disturbance of fission and fusion caused by alpha-synuclein can be rescued via PINK1 and Parkin co-expression [39]. Additionally, the NIX-mediated mitophagy pathway independently restores mitophagy in the PD patient cell lines without functional PINK1 and Parkin [40]. On the other hand, USP30 is identified as a deubiquitinase for mitophagy regulation negatively. Overexpression of USP30 inhibits mitophagy by removing ubiquitin on damaged mitochondria [41]. Several USP30 inhibitors are under development for the treatment of PD [42]. Despite PINK1/Parkin pathway dysfunction being a major contribution to PD pathologies, more studies have shown other genes that influence mitophagy involved in PD. DJ-1 is a mitochondrial location redox sensor. Loss of DJ-1 leads to mitochondrial fragmentation that may affect mitophagy. Mutation of DJ-1 causes a recessive form of PD [43][44]. Mutation of LRRK2, a large multidomain protein, influences mitophagy via regulating the PINK1/Parkin pathway, causing an autosomal dominant form of PD [45][46][47]. These findings suggest that mitochondrial dysfunction is strongly related to PD pathogenesis, and induction of mitophagy rescuing mitochondrial biogenesis may ameliorate PD pathology.

Notably, most PD patients are classified as sporadic patients, whereas only less than 10% of PD cases are diagnosed as familial PD. Among familial PD patients, important mutations in DJ-1 and GBA are implicated in maintaining normal mitochondrial function [94,95]. Although the biogenesis of these two categories is different, a significant difference between both groups for clinical profile or motor symptoms cannot be observed [113]. Since the pathogenic cause of PD is complicated and is still unknown, an effective strategy that can radically cure PD remains unavailable [114]. By eliminating dysfunctional mitochondria and degrading abnormal structural proteins, mitophagy is a potential strategy for PD treatment.

Notably, most PD patients are classified as sporadic patients, whereas only less than 10% of PD cases are diagnosed as familial PD. Among familial PD patients, important mutations in DJ-1 and GBA are implicated in maintaining normal mitochondrial function [28][29]. Although the biogenesis of these two categories is different, a significant difference between both groups for clinical profile or motor symptoms cannot be observed [48]. Since the pathogenic cause of PD is complicated and is still unknown, an effective strategy that can radically cure PD remains unavailable [49]. By eliminating dysfunctional mitochondria and degrading abnormal structural proteins, mitophagy is a potential strategy for PD treatment.

3. Alzheimer’s Disease

Alzheimer’s disease (AD) is the most common neurodegenerative disease; its symptoms include memory loss and cognitive impairments. Dysfunctional mitochondria accumulation, damaged synapse, disease-defining amyloid-β (Aβ) oligomers, and intracellular neurofibrillary tangles (NFTs) are the fundamental pathological hallmarks of AD [9,115].

Alzheimer’s disease (AD) is the most common neurodegenerative disease; its symptoms include memory loss and cognitive impairments. Dysfunctional mitochondria accumulation, damaged synapse, disease-defining amyloid-β (Aβ) oligomers, and intracellular neurofibrillary tangles (NFTs) are the fundamental pathological hallmarks of AD [50][51].

A series of evidence suggests that amyloid deposition is a common pathological hallmark in numerous neurodegenerative diseases including AD; an excessive aggregation of amyloid-beta impairs neurons, causing their death [116]. Besides, amyloid precursor protein-derived 

A series of evidence suggests that amyloid deposition is a common pathological hallmark in numerous neurodegenerative diseases including AD; an excessive aggregation of amyloid-beta impairs neurons, causing their death [52]. Besides, amyloid precursor protein-derived 

C-terminal fragments (APP-CTFs) accumulating in AD patients and AD mouse models trigger mitochondrial damage and mitophagy failure in an Aβ-independent manner [117]. Increasing evidence shows the existence of a strong relationship between mitophagy failure and neuron degeneration. Studies by Fang et al. showed that mitophagy is reduced in APP/PS1 mouse model, Aβ-based 

-terminal fragments (APP-CTFs) accumulating in AD patients and AD mouse models trigger mitochondrial damage and mitophagy failure in an Aβ-independent manner [53]. Increasing evidence shows the existence of a strong relationship between mitophagy failure and neuron degeneration. Studies by Fang et al. showed that mitophagy is reduced in APP/PS1 mouse model, Aβ-based 

C. elegans model, and even in the hippocampus of AD patients’ brains [118]. Another study also showed mitochondria fragmentation and dysfunction in Aβ expression of 

 model, and even in the hippocampus of AD patients’ brains [54]. Another study also showed mitochondria fragmentation and dysfunction in Aβ expression of 

Drosophila melanogaster, suggesting that mitophagy failure may be a hallmark of AD [119]. Considering that mitochondria regulate energy generation in neurons, dysfunctional mitochondria will badly influence the signal delivery from one neuron to another. In addition, hyper-phosphorylated Tau, as another hallmark protein in AD, seemingly aggregates in AD patients and the loss of Tau is neuroprotective [120]. Numerous findings suggest that Tau expression leads to impairment in mitophagy [121,122,123]. This indicates that protein aggregate degradation is a potential strategy to reduce their impairment to CNS and protect neurons.

, suggesting that mitophagy failure may be a hallmark of AD [55]. Considering that mitochondria regulate energy generation in neurons, dysfunctional mitochondria will badly influence the signal delivery from one neuron to another. In addition, hyper-phosphorylated Tau, as another hallmark protein in AD, seemingly aggregates in AD patients and the loss of Tau is neuroprotective [56]. Numerous findings suggest that Tau expression leads to impairment in mitophagy [57][58][59]. This indicates that protein aggregate degradation is a potential strategy to reduce their impairment to CNS and protect neurons.

On the other hand, mitochondria are highly dynamic organelles; their shape and size, distributive situation, and physiological functions are regulated by their fission and fusion [124]. These processes include Drp1-mediated fission and OPA1-mediated fusion of mitochondria. Recent studies have reported that both levels of Drp1 and OPA1 are remarkably decreased in AD [125,126]. This indicates that the imbalance between fission and fusion affects the normal structure and function of mitochondria, promoting AD pathology. Mitophagy and mitochondrial dynamics interact with each other to maintain a healthy mitochondrial recycling balance [127]. Based on accumulating evidence, abnormal structures, functional defects, and variations in mitochondrial dynamics, and decline in the level of mitophagy are observed in neurons of AD patients [128,129]. Moreover, as terminally differentiated cells, neuronal cells are susceptive to various types of mitochondrial dysfunctions and irreversible damage, eventually leading to neuron death once compromising mitophagy cannot recycle damaged or redundant mitochondria properly.

On the other hand, mitochondria are highly dynamic organelles; their shape and size, distributive situation, and physiological functions are regulated by their fission and fusion [60]. These processes include Drp1-mediated fission and OPA1-mediated fusion of mitochondria. Recent studies have reported that both levels of Drp1 and OPA1 are remarkably decreased in AD [61][62]. This indicates that the imbalance between fission and fusion affects the normal structure and function of mitochondria, promoting AD pathology. Mitophagy and mitochondrial dynamics interact with each other to maintain a healthy mitochondrial recycling balance [63]. Based on accumulating evidence, abnormal structures, functional defects, and variations in mitochondrial dynamics, and decline in the level of mitophagy are observed in neurons of AD patients [64][65]. Moreover, as terminally differentiated cells, neuronal cells are susceptive to various types of mitochondrial dysfunctions and irreversible damage, eventually leading to neuron death once compromising mitophagy cannot recycle damaged or redundant mitochondria properly.

Recent research has reported compounds including beta-Asarone and UMI-77 that help improve the learning and memory of AD mice as well as ameliorate disease pathologies by promoting mitophagy [49,130]. Another two compounds (nicotinamide riboside and urolithin A) are also reported to induce mitophagy. Nicotinamide riboside is a precursor of NAD

Recent research has reported compounds including beta-Asarone and UMI-77 that help improve the learning and memory of AD mice as well as ameliorate disease pathologies by promoting mitophagy [66][67]. Another two compounds (nicotinamide riboside and urolithin A) are also reported to induce mitophagy. Nicotinamide riboside is a precursor of NAD

+

 and can be metabolized to produce NAD

+ in cells and reduces Aβ levels in APP/PS1 mice [131,132,133]. This suggests that enhancement of NAD

 in cells and reduces Aβ levels in APP/PS1 mice [68][69][70]. This suggests that enhancement of NAD

+ may be beneficial for AD treatment. Urolithin A (UA) is a natural compound that ameliorates cognitive decline in the APP/PS1 mouse model via mitophagy activation [81,118,134]. A recent study showed that rapamycin, an mTOR inhibitor that can induce autophagy, also induces mitophagy and alleviates cognition in a mouse model of Alzheimer’s disease [135]. This suggests that mitochondrial dysfunction is the most prominent feature of AD, whereas induction of mitophagy appears as a potential strategy for AD treatment.

 may be beneficial for AD treatment. Urolithin A (UA) is a natural compound that ameliorates cognitive decline in the APP/PS1 mouse model via mitophagy activation [15][54][71]. A recent study showed that rapamycin, an mTOR inhibitor that can induce autophagy, also induces mitophagy and alleviates cognition in a mouse model of Alzheimer’s disease [72]. This suggests that mitochondrial dysfunction is the most prominent feature of AD, whereas induction of mitophagy appears as a potential strategy for AD treatment.

4. Huntington’s Disease

Huntington’s disease (HD) is a rare autosomal dominant disorder caused by an expansion of cytosine-adenine-guanine (CAG) repeats within the huntingtin (Htt) gene. This results in polyglutamine (polyQ) expansion in the encoded huntingtin protein. Since the clinical syndrome of HD displays apparent neuropathic traits including motor dysfunction, cognitive decline, and psychiatric disturbances, it can also be classified into neurodegenerative diseases. The prevalence of Huntington’s disease is estimated at 4–10 per 100,000 in the Western world and the onset time and severity of HD is positively related to the length of CAG repeats [136]. Although the pathogenesis of HD remains unclear and lacks effective therapeutic methods, increasing evidence reveals that mitochondria regulate the HD pathology process.

Huntington’s disease (HD) is a rare autosomal dominant disorder caused by an expansion of cytosine-adenine-guanine (CAG) repeats within the huntingtin (Htt) gene. This results in polyglutamine (polyQ) expansion in the encoded huntingtin protein. Since the clinical syndrome of HD displays apparent neuropathic traits including motor dysfunction, cognitive decline, and psychiatric disturbances, it can also be classified into neurodegenerative diseases. The prevalence of Huntington’s disease is estimated at 4–10 per 100,000 in the Western world and the onset time and severity of HD is positively related to the length of CAG repeats [73]. Although the pathogenesis of HD remains unclear and lacks effective therapeutic methods, increasing evidence reveals that mitochondria regulate the HD pathology process.

Aberrant mitochondrial morphology, fragmentation, and decreased mitochondrial mass are observed in HD patients. Besides, the mutant huntingtin severely impairs mitochondrial respiration and ATP production, suggesting that energy metabolism in HD may fall into disorder [137]. As for the fragmented mitochondria in HD pathology, scientists believe that excessive mitochondrial fission is potentially caused by increasing levels of Drp1 and decreasing levels of OPA1 and mitofusin 1 (Mfn1) [98,138,139]. These findings show that mutant huntingtin impairs mitochondria by disturbing mitochondrial dynamics, further influencing its function. This indicates that functional mitochondria restoration might be an effective treatment for HD. In line with the findings by Khalil’s [140] group, PINK1 overexpression, which regulates Parkin-mediated mitophagy, partially restored mitophagy and promoted neuroprotection in Huntington’s disease. Nonetheless, Guo et al. [99] suggested that accumulation of valosin-containing protein (VCP), an mtHtt-binding protein on the mitochondria, induces superabundant mitophagy, causing the death of neurons. Moreover, Rhes, a type of GTPase, was reported to upregulate mitophagy via the NIX receptor. This led to striatal cell death and striatal lesions, speculating that exaggerated mitophagy might be a contributing factor of HD [100,141]. Overall, abnormal mitochondrial size and morphology have been confirmed in HD, but the role of mitophagy (i.e., eliminating dysfunctional and unwanted mitochondria) remains controversial.

Aberrant mitochondrial morphology, fragmentation, and decreased mitochondrial mass are observed in HD patients. Besides, the mutant huntingtin severely impairs mitochondrial respiration and ATP production, suggesting that energy metabolism in HD may fall into disorder [74]. As for the fragmented mitochondria in HD pathology, scientists believe that excessive mitochondrial fission is potentially caused by increasing levels of Drp1 and decreasing levels of OPA1 and mitofusin 1 (Mfn1) [32][75][76]. These findings show that mutant huntingtin impairs mitochondria by disturbing mitochondrial dynamics, further influencing its function. This indicates that functional mitochondria restoration might be an effective treatment for HD. In line with the findings by Khalil’s [77] group, PINK1 overexpression, which regulates Parkin-mediated mitophagy, partially restored mitophagy and promoted neuroprotection in Huntington’s disease. Nonetheless, Guo et al. [33] suggested that accumulation of valosin-containing protein (VCP), an mtHtt-binding protein on the mitochondria, induces superabundant mitophagy, causing the death of neurons. Moreover, Rhes, a type of GTPase, was reported to upregulate mitophagy via the NIX receptor. This led to striatal cell death and striatal lesions, speculating that exaggerated mitophagy might be a contributing factor of HD [34][78]. Overall, abnormal mitochondrial size and morphology have been confirmed in HD, but the role of mitophagy (i.e., eliminating dysfunctional and unwanted mitochondria) remains controversial.

References

  1. Fang, E.F.; Hou, Y.J.; Lautrup, S.; Jensen, M.B.; Yang, B.M.; SenGupta, T.; Caponio, D.; Khezri, R.; Demarest, T.G.; Aman, Y.; et al. NAD(+) augmentation restores mitophagy and limits accelerated aging in Werner syndrome. Nat. Commun. 2019, 10, 1–18.
  2. Wu, N.N.; Zhang, Y.M.; Ren, J. Mitophagy, Mitochondrial Dynamics, and Homeostasis in Cardiovascular Aging. Oxidative Med. Cell. Longev. 2019, 2019, 9825061.
  3. You, W.J.; Min, X.Y.; Zhang, X.J.; Qian, B.; Pang, S.S.; Ding, Z.N.; Li, C.F.; Gao, X.; Di, R.M.; Cheng, Y.L.; et al. Cardiac-specific expression of heat shock protein 27 attenuated endotoxin-induced cardiac dysfunction and mortality in mice through a pi3k/akt-dependent mechanism. Shock 2009, 32, 108–117.
  4. Lin, S.L.; Wang, Y.N.; Zhang, X.J.; Kong, Q.Y.; Li, C.F.; Li, Y.H.; Ding, Z.N.; Liu, L. HSP27 Alleviates Cardiac Aging in Mice via a Mechanism Involving Antioxidation and Mitophagy Activation. Oxidative Med. Cell. Longev. 2016, 2016, 2586706.
  5. Wang, S.Y.; Kandadi, M.R.; Ren, J. Double knockout of Akt2 and AMPK predisposes cardiac aging without affecting lifespan: Role of autophagy and mitophagy. Biochim. Biophys. Acta-Mol. Basis Dis. 2019, 1865, 1865–1875.
  6. Harman, D. Aging—A theory based on free-radical and radiation-chemistry. J. Gerontol. 1956, 11, 298–300.
  7. Harman, D. Free Radical Theory of Aging: An Update Increasing the Functional Life Span. Ann. N. Y. Acad. Sci. 2006, 1, 10–21.
  8. Zorov, D.B.; Juhaszova, M.; Sollott, S.J. Mitochondrial reactive oxygen species (ros) and ros-induced ros release. Physiol. Rev. 2014, 94, 909–950.
  9. Hess, D.T.; Matsumoto, A.; Kim, S.O.; Marshall, H.E.; Stamler, J.S. Protein S-nitrosylation: Purview and parameters. Nat. Rev. Mol. Cell Biol. 2005, 6, 150–166.
  10. Nakamura, T.; Oh, C.K.; Liao, L.J.; Zhang, X.; Lopez, K.M.; Gibbs, D.; Deal, A.K.; Scott, H.R.; Spencer, B.; Masliah, E.; et al. Noncanonical transnitrosylation network contributes to synapse loss in Alzheimer’s disease. Science 2021, 371, 6526.
  11. Rizza, S.; Cardaci, S.; Montagna, C.; Di Giacomo, G.; De Zio, D.; Bordi, M.; Maiani, E.; Campello, S.; Borreca, A.; Puca, A.A.; et al. S-nitrosylation drives cell senescence and aging in mammals by controlling mitochondrial dynamics and mitophagy. Proc. Natl. Acad. Sci. USA 2018, 115, E3388–E3397.
  12. Carter, H.N.; Kim, Y.; Erlich, A.T.; Zarrin-khat, D.; Hood, D.A. Autophagy and mitophagy flux in young and aged skeletal muscle following chronic contractile activity. J. Physiol. 2018, 596, 3567–3584.
  13. Chen, C.C.W.; Erlich, A.T.; Crilly, M.J.; Hood, D.A. Parkin is required for exercise-induced mitophagy in muscle: Impact of aging. Am. J. Physiol. Endocrinol. Metab. 2018, 315, E404–E415.
  14. Zampieri, S.; Pietrangelo, L.; Loefler, S.; Fruhmann, H.; Vogelauer, M.; Burggraf, S.; Pond, A.; Grim-Stieger, M.; Cvecka, J.; Sedliak, M.; et al. Lifelong Physical Exercise Delays Age-Associated Skeletal Muscle Decline. J. Gerontol. Ser. A-Biol. Sci. Med. Sci. 2015, 70, 163–173.
  15. Andreux, P.A.; Blanco-Bose, W.; Ryu, D.; Burdet, F.; Ibberson, M.; Aebischer, P.; Auwerx, J.; Singh, A.; Rinsch, C. The mitophagy activator urolithin A is safe and induces a molecular signature of improved mitochondrial and cellular health in humans. Nat. Metab. 2019, 1, 595–603.
  16. Dauer, W.; Przedborski, S. Parkinson’s disease: Mechanisms and models. Neuron 2003, 39, 889–909.
  17. Federico, A.; Cardaioli, E.; Da Pozzo, P.; Formichi, P.; Gallus, G.N.; Radi, E. Mitochondria, oxidative stress and neurodegeneration. J. Neurol. Sci. 2012, 322, 254–262.
  18. Ryan, B.J.; Hoek, S.; Fon, E.A.; Wade-Martins, R. Mitochondrial dysfunction and mitophagy in Parkinson’s: From familial to sporadic disease. Trends Biochem. Sci. 2015, 40, 200–210.
  19. Dias, V.; Junn, E.; Mouradian, M.M. The Role of Oxidative Stress in Parkinson’s Disease. J. Parkinsons Dis. 2013, 3, 461–491.
  20. Rugarli, E.I.; Langer, T. Mitochondrial quality control: A matter of life and death for neurons. EMBO J. 2012, 31, 1336–1349.
  21. Schapira, A. Mitochondrial Pathology in Parkinson’s Disease. Mt. Sinai J. Med. 2011, 78, 872–881.
  22. Quinn, P.M.J.; Moreira, P.I.; Ambrosio, A.F.; Alves, C.H. PINK1/PARKIN signalling in neurodegeneration and neuroinflammation. Acta Neuropathol. Commun. 2020, 8.
  23. Cai, X.Z.; Qiao, J.; Knox, T.; Iriah, S.; Kulkarni, P.; Madularu, D.; Morrison, T.; Waszczak, B.; Hartner, J.C.; Ferris, C.F. In search of early neuroradiological biomarkers for Parkinson’s Disease: Alterations in resting state functional connectivity and gray matter microarchitecture in PINK1-/-rats. Brain Res. 2019, 1706, 58–67.
  24. Imai, Y. PINK1-Parkin signaling in Parkinson’s disease: Lessons from Drosophila. Neurosci. Res. 2020, 159, 40–46.
  25. Narendra, D.P.; Jin, S.M.; Tanaka, A.; Suen, D.F.; Gautier, C.A.; Shen, J.; Cookson, M.R.; Youle, R.J. PINK1 Is Selectively Stabilized on Impaired Mitochondria to Activate Parkin. PLoS Biol. 2010, 8, 21.
  26. Pickrell, A.M.; Youle, R.J. The Roles of PINK1, Parkin, and Mitochondrial Fidelity in Parkinson’s Disease. Neuron 2015, 85, 257–273.
  27. Davis, A.A.; Andruska, K.M.; Benitez, B.A.; Racette, B.A.; Perlmutter, J.S.; Cruchaga, C. Variants in GBA, SNCA, and MAPT influence Parkinson disease risk, age at onset, and progression. Neurobiol. Aging 2016, 37.
  28. Chen, R.; Park, H.-A.; Mnatsakanyan, N.; Niu, Y.; Licznerski, P.; Wu, J.; Miranda, P.; Graham, M.; Tang, J.; Boon, A.J.W.; et al. Parkinson’s disease protein DJ-1 regulates ATP synthase protein components to increase neuronal process outgrowth. Cell Death Dis. 2019, 10.
  29. Li, H.Y.; Ham, A.; Ma, T.C.; Kuo, S.H.; Kanter, E.; Kim, D.; Ko, H.S.; Quan, Y.; Sardi, S.P.; Li, A.Q.; et al. Mitochondrial dysfunction and mitophagy defect triggered by heterozygous GBA mutations. Autophagy 2019, 15, 113–130.
  30. Prieto, J.; Leon, M.; Ponsoda, X.; Sendra, R.; Bort, R.; Ferrer-Lorente, R.; Raya, A.; Lopez-Garcia, C.; Torres, J. Early ERK1/2 activation promotes DRP1-dependent mitochondrial fission necessary for cell reprogramming. Nat. Commun. 2016, 7, 1–13.
  31. Song, Z.; Chen, H.; Fiket, M.; Alexander, C.; Chan, D.C. OPA1 processing controls mitochondrial fusion and is regulated by mRNA splicing, membrane potential, and Yme1L. J. Cell Biol. 2007, 178, 749–755.
  32. Kim, J.; Moody, J.P.; Edgerly, C.K.; Bordiuk, O.L.; Cormier, K.; Smith, K.; Beal, M.F.; Ferrante, R.J. Mitochondrial loss, dysfunction and altered dynamics in Huntington’s disease. Hum. Mol. Genet. 2010, 19, 3919–3935.
  33. Guo, X.; Sun, X.; Hu, D.; Wang, Y.-J.; Fujioka, H.; Vyas, R.; Chakrapani, S.; Joshi, A.U.; Luo, Y.; Mochly-Rosen, D.; et al. VCP recruitment to mitochondria causes mitophagy impairment and neurodegeneration in models of Huntington’s disease. Nat. Commun. 2016, 7, 1–17.
  34. Sharma, M.; Jarquin, U.N.R.; Rivera, O.; Kazantzis, M.; Eshraghi, M.; Shahani, N.; Sharma, V.; Tapia, R.; Subramaniam, S. Rhes, a striatal-enriched protein, promotes mitophagy via Nix. Proc. Natl. Acad. Sci. USA 2019, 116, 23760–23771.
  35. Maruyama, H.; Morino, H.; Ito, H.; Izumi, Y.; Kato, H.; Watanabe, Y.; Kinoshita, Y.; Kamada, M.; Nodera, H.; Suzuki, H.; et al. Mutations of optineurin in amyotrophic lateral sclerosis. Nature 2010, 465, 223–226.
  36. Freischmidt, A.; Wieland, T.; Richter, B.; Ruf, W.; Schaeffer, V.; Muller, K.; Marroquin, N.; Nordin, F.; Hubers, A.; Weydt, P.; et al. Haploinsufficiency of TBK1 causes familial ALS and fronto-temporal dementia. Nat. Neurosci. 2015, 18, 631–636.
  37. Youle, R.J.; Narendra, D.P. Mechanisms of mitophagy. Nat. Rev. Mol. Cell Biol. 2011, 12, 9–14.
  38. Suen, D.F.; Narendra, D.P.; Tanaka, A.; Manfredi, G.; Youle, R.J. Parkin overexpression selects against a deleterious mtDNA mutation in heteroplasmic cybrid cells. Proc. Natl. Acad. Sci. USA 2010, 107, 11835–11840.
  39. Kamp, F.; Exner, N.; Lutz, A.K.; Wender, N.; Hegermann, J.; Brunner, B.; Nuscher, B.; Bartels, T.; Giese, A.; Beyer, K.; et al. Inhibition of mitochondrial fusion by alpha-synuclein is rescued by PINK1, Parkin and DJ-1. EMBO J. 2010, 29, 3571–3589.
  40. Koentjoro, B.; Park, J.S.; Sue, C.M. Nix restores mitophagy and mitochondrial function to protect against PINK1/Parkin-related Parkinson’s disease. Sci Rep. 2017, 7, 11.
  41. Bingol, B.; Tea, J.S.; Phu, L.; Reichelt, M.; Bakalarski, C.E.; Song, Q.H.; Foreman, O.; Kirkpatrick, D.S.; Sheng, M.G. The mitochondrial deubiquitinase USP30 opposes parkin-mediated mitophagy. Nature 2014, 510, 370.
  42. Miller, S.; Muqit, M.M.K. Therapeutic approaches to enhance PINK1/Parkin mediated mitophagy for the treatment of Parkinson’s disease. Neurosci. Lett. 2019, 705, 7–13.
  43. Thomas, K.J.; McCoy, M.K.; Blackinton, J.; Beilina, A.; van der Brug, M.; Sandebring, A.; Miller, D.; Maric, D.; Cedazo-Minguez, A.; Cookson, M.R. DJ-1 acts in parallel to the PINK1/parkin pathway to control mitochondrial function and autophagy. Hum. Mol. Genet. 2011, 20, 40–50.
  44. Krebiehl, G.; Ruckerbauer, S.; Burbulla, L.F.; Kieper, N.; Maurer, B.; Waak, J.; Wolburg, H.; Gizatullina, Z.; Gellerich, F.N.; Woitalla, D.; et al. Reduced Basal Autophagy and Impaired Mitochondrial Dynamics Due to Loss of Parkinson’s Disease-Associated Protein DJ-1. PLoS ONE 2010, 5, e9367.
  45. Pfeffer, S.R. Rab GTPases: Master regulators that establish the secretory and endocytic pathways. Mol. Biol. Cell 2017, 28, 712–715.
  46. Wauters, F.; Cornelissen, T.; Imberechts, D.; Martin, S.; Koentjoro, B.; Sue, C.; Vangheluwe, P.; Vandenberghe, W. LRRK2 mutations impair depolarization-induced mitophagy through inhibition of mitochondrial accumulation of RAB10. Autophagy 2020, 16, 203–222.
  47. Bonello, F.; Hassoun, S.M.; Mouton-Liger, F.; Shin, Y.S.; Muscat, A.; Tesson, C.; Lesage, S.; Beart, P.M.; Brice, A.; Krupp, J.; et al. LRRK2 impairs PINK1/Parkin-dependent mitophagy via its kinase activity: Pathologic insights into Parkinson’s disease. Hum. Mol. Genet. 2019, 28, 1645–1660.
  48. Jukkarwala, A. Comparative study of clinical profile between familial and sporadic Parkinson’s disease. J. Med Allied Sci. 2017, 7, 1.
  49. Luo, A.; Hoffer, A.; Hoffer, B.; Qi, X. Mitochondria: A Therapeutic Target for Parkinson’s Disease? Int. J. Mol. Sci. 2015, 16, 20704–20730.
  50. Martinez-Vicente, M. Neuronal Mitophagy in Neurodegenerative Diseases. Front. Mol. Neurosci. 2017, 10, 64.
  51. Pradeepkiran, J.A.; Reddy, P.H. Defective mitophagy in Alzheimer’s disease. Ageing Res. Rev. 2020, 64.
  52. Chiti, F.; Dobson, C.M. Protein misfolding, functional amyloid, and human disease. Annu. Rev. Biochem. 2006, 75, 333–366.
  53. Vaillant-Beuchot, L.; Mary, A.; Pardossi-Piquard, R.; Bourgeois, A.; Lauritzen, I.; Eysert, F.; Kinoshita, P.F.; Cazareth, J.; Badot, C.; Fragaki, K.; et al. Accumulation of amyloid precursor protein C-terminal fragments triggers mitochondrial structure, function, and mitophagy defects in Alzheimer’s disease models and human brains. Acta Neuropathol. 2021, 141, 39–65.
  54. Fang, E.F.; Hou, Y.; Palikaras, K.; Adriaanse, B.A.; Kerr, J.S.; Yang, B.; Lautrup, S.; Hasan-Olive, M.M.; Caponio, D.; Xiuli, D.; et al. Mitophagy inhibits amyloid-β and tau pathology and reverses cognitive deficits in models of Alzheimer’s disease. Nat. Neurosci. 2019, 22, 401–412.
  55. Wang, X.J.; Davis, R.L. Early Mitochondrial Fragmentation and Dysfunction in a Drosophila Model for Alzheimer’s Disease. Mol. Neurobiol. 2021, 58, 143–155.
  56. Maphis, N.; Xu, G.; Kokiko-Cochran, O.; Cardona, A.; Ransohoff, R.; Lamb, B.; Bhaskar, K. Loss of tau rescues inflammation-mediated neurodegeneration. Front. Neurosci. 2015, 9, 196.
  57. Chen, C.; Turnbull, D.M.; Reeve, A.K. Mitochondrial Dysfunction in Parkinson’s Disease-Cause or Consequence? Biology 2019, 8, 38.
  58. Kocahan, S.; Dogan, Z. Mechanisms of Alzheimer’s Disease Pathogenesis and Prevention: The Brain, Neural Pathology, N-methyl-D-aspartate Receptors, Tau Protein and Other Risk Factors. Clin. Psychopharmacol. Neurosci. 2017, 15, 1–8.
  59. Lane, R.K.; Hilsabeck, T.; Rea, S.L. The role of mitochondrial dysfunction in age-related diseases. Biochim. Biophys. Acta Bioenerg. 2015, 1847, 1387–1400.
  60. Chan, D.C. Mitochondrial fusion and fission in mammals. Annu. Rev. Cell Dev. Biol. 2006, 22, 79–99.
  61. Wang, X.L.; Su, B.; Lee, H.G.; Li, X.Y.; Perry, G.; Smith, M.A.; Zhu, X.W. Impaired Balance of Mitochondrial Fission and Fusion in Alzheimer’s Disease. J. Neurosci. 2009, 29, 9090–9103.
  62. Li, X.-C.; Hu, Y.; Wang, Z.-h.; Luo, Y.; Zhang, Y.; Liu, X.-P.; Feng, Q.; Wang, Q.; Ye, K.; Liu, G.-P.; et al. Human wild-type full-length tau accumulation disrupts mitochondrial dynamics and the functions via increasing mitofusins. Sci. Rep. 2016, 6, 24756.
  63. Twig, G.; Shirihai, O.S. The Interplay between Mitochondrial Dynamics and Mitophagy. Antioxid. Redox Signal. 2011, 14, 1939–1951.
  64. García-Prat, L.; Martínez-Vicente, M.; Perdiguero, E.; Ortet, L.; Rodríguez-Ubreva, J.; Rebollo, E.; Ruiz-Bonilla, V.; Gutarra, S.; Ballestar, E.; Serrano, A.L.; et al. Autophagy maintains stemness by preventing senescence. Nature 2016, 534, S3–S4.
  65. Song, M.; Zhao, X.; Song, F. Aging-Dependent Mitophagy Dysfunction in Alzheimer’s Disease. Mol. Neurobiol. 2021.
  66. Cen, X.; Chen, Y.; Xu, X.; Wu, R.; He, F.; Zhao, Q.; Sun, Q.; Yi, C.; Wu, J.; Najafov, A.; et al. Pharmacological targeting of MCL-1 promotes mitophagy and improves disease pathologies in an Alzheimer’s disease mouse model. Nat. Commun. 2020, 11, 5731.
  67. Han, Y.F.; Wang, N.B.; Kang, J.; Fang, Y.Q. beta-Asarone improves learning and memory in A beta(1-42)-induced Alzheimer’s disease rats by regulating PINK1-Parkin-mediated mitophagy. Metab. Brain Dis. 2020, 35, 1109–1117.
  68. Lautrup, S.; Sinclair, D.A.; Mattson, M.P.; Fang, E.F. NAD(+) in Brain Aging and Neurodegenerative Disorders. Cell Metab. 2019, 30, 630–655.
  69. Fang, E.F.; Scheibye-Knudsen, M.; Brace, L.E.; Kassahun, H.; SenGupta, T.; Nilsen, H.; Mitchell, J.R.; Croteau, D.L.; Bohr, V.A. Defective Mitophagy in XPA via PARP-1 Hyperactivation and NAD(+)/SIRT1 Reduction. Cell 2014, 157, 882–896.
  70. Sorrentino, V.; Romani, M.; Mouchiroud, L.; Beck, J.S.; Zhang, H.; D’Amico, D.; Moullan, N.; Potenza, F.; Schmid, A.W.; Rietsch, S.; et al. Enhancing mitochondrial proteostasis reduces amyloid-β proteotoxicity. Nature 2017, 552, 187–193.
  71. Gong, Z.; Huang, J.; Xu, B.; Ou, Z.; Zhang, L.; Lin, X.; Ye, X.; Kong, X.; Long, D.; Sun, X.; et al. Urolithin A attenuates memory impairment and neuroinflammation in APP/PS1 mice. J. Neuroinflamm. 2019, 16, 1–13.
  72. Wang, H.; Fu, J.; Xu, X.; Yang, Z.; Zhang, T. Rapamycin activates mitophagy and alleviates cognitive and synaptic plasticity deficits in a mouse model of Alzheimer’s disease. J. Gerontol. Ser. A 2021.
  73. Ross, C.A.; Tabrizi, S.J. Huntington’s disease: From molecular pathogenesis to clinical treatment. Lancet Neurol. 2011, 10, 83–98.
  74. Milakovic, T.; Johnson, G.V.W. Mitochondrial respiration and ATP production are significantly impaired in striatal cells expressing mutant Huntingtin. J. Biol. Chem. 2005, 280, 30773–30782.
  75. Shirendeb, U.; Reddy, A.P.; Manczak, M.; Calkins, M.J.; Mao, P.Z.; Tagle, D.A.; Reddy, P.H. Abnormal mitochondrial dynamics, mitochondrial loss and mutant huntingtin oligomers in Huntington’s disease: Implications for selective neuronal damage. Hum. Mol. Genet. 2011, 20, 1438–1455.
  76. Cherubini, M.; Lopez-Molina, L.; Gines, S. Mitochondrial fission in Huntington’s disease mouse striatum disrupts ER-mitochondria contacts leading to disturbances in Ca2+ efflux and Reactive Oxygen Species (ROS) homeostasis. Neurobiol. Dis. 2020, 136, 15.
  77. Khalil, B.; El Fissi, N.; Aouane, A.; Cabirol-Pol, M.J.; Rival, T.; Lievens, J.C. PINK1-induced mitophagy promotes neuroprotection in Huntington’s disease. Cell Death Dis. 2015, 6, 12.
  78. Subramaniam, S. Exaggerated mitophagy: A weapon of striatal destruction in the brain? Biochem. Soc. Trans. 2020, 48, 709–717.
More