RAF1 Gene | Encyclopedia MDPI

RAF1 Gene: History

Subjects: Genetics & Heredity

Contributors:

Karina Chen

Raf-1 proto-oncogene, serine/threonine kinase

genes

1. Normal Function

The RAF1 gene provides instructions for making a protein that is part of a signaling pathway called the RAS/MAPK pathway, which transmits chemical signals from outside the cell to the cell's nucleus. RAS/MAPK signaling helps control the growth and division (proliferation) of cells, the process by which cells mature to carry out specific functions (differentiation), cell movement (migration), and the self-destruction of cells (apoptosis).

The RAF1 gene belongs to a class of genes known as oncogenes. When mutated, oncogenes have the potential to cause normal cells to become cancerous.

2. Health Conditions Related to Genetic Changes

2.1. Noonan syndrome

More than 25 mutations causing Noonan syndrome have been identified in the RAF1 gene. Noonan syndrome is characterized by mildly unusual facial characteristics, short stature, heart defects, bleeding problems, skeletal malformations, and many other signs and symptoms. The RAF1 gene mutations change single protein building blocks (amino acids) in the RAF1 protein. These changes increase protein activity and disrupt the regulation of the RAS/MAPK signaling pathway causing problems with cell division, apoptosis, cell differentiation, and cell migration. Researchers believe that this disruption in normal cell processes plays a role in the signs and symptoms of Noonan syndrome, specifically cardiac abnormalities. It has been noted that people with Noonan syndrome caused by a RAF1 gene mutation have a greater incidence of heart defects than other people with Noonan syndrome, specifically a condition called hypertrophic cardiomyopathy, which is a thickening of the heart muscle that forces the heart to work harder to pump blood.

2.2. Noonan syndrome with multiple lentigines

At least two mutations in the RAF1 gene have been found to cause Noonan syndrome with multiple lentigines (formerly called LEOPARD syndrome). This condition is characterized by multiple brown skin spots (lentigines), heart defects, short stature, a sunken or protruding chest, and distinctive facial features. The RAF1 gene mutations change single amino acids in the RAF1 protein: One mutation replaces the amino acid serine with the amino acid leucine at position 257 (written Ser257Leu or S257L) and the other mutation replaces the amino acid leucine with the amino acid valine at position 613 (written Leu613Val or L613V).

The RAF1 gene changes that cause Noonan syndrome with multiple lentigines are believed to abnormally activate the RAF1 protein, which disrupts the regulation of the RAS/MAPK signaling pathway that controls cell functions such as growth and division. This misregulation can result in the various features of Noonan syndrome with multiple lentigines.

2.3. Cancers

Some gene mutations are acquired during a person's lifetime and are present only in certain cells. These changes are called somatic mutations and are not inherited. Somatic mutations in the RAF1 gene are involved in the development of several types of cancer. These mutations lead to a RAF1 protein that is always active and can direct cells to grow and divide uncontrollably. Studies suggest that RAF1 gene mutations may be found in ovarian, lung, and colorectal cancers. Somatic mutations in the RAF1 gene are a rare cause of cancer.

For reasons that are unclear, inherited mutations in the RAF1 gene do not appear to increase the risk of cancer in people with Noonan syndrome with multiple lentigines or Noonan syndrome.

3. Other Names for This Gene

c-Raf
CRAF
Oncogene RAF1
raf proto-oncogene serine/threonine protein kinase
Raf-1
RAF1_HUMAN

This entry is adapted from the peer-reviewed paper https://medlineplus.gov/genetics/gene/raf1

References

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Kobayashi T, Aoki Y, Niihori T, Cavé H, Verloes A, Okamoto N, Kawame H,Fujiwara I, Takada F, Ohata T, Sakazume S, Ando T, Nakagawa N, Lapunzina P,Meneses AG, Gillessen-Kaesbach G, Wieczorek D, Kurosawa K, Mizuno S, Ohashi H,David A, Philip N, Guliyeva A, Narumi Y, Kure S, Tsuchiya S, Matsubara Y.Molecular and clinical analysis of RAF1 in Noonan syndrome and related disorders:dephosphorylation of serine 259 as the essential mechanism for mutant activation.Hum Mutat. 2010 Mar;31(3):284-94. doi: 10.1002/humu.21187.
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Razzaque MA, Nishizawa T, Komoike Y, Yagi H, Furutani M, Amo R, Kamisago M,Momma K, Katayama H, Nakagawa M, Fujiwara Y, Matsushima M, Mizuno K, Tokuyama M, Hirota H, Muneuchi J, Higashinakagawa T, Matsuoka R. Germline gain-of-functionmutations in RAF1 cause Noonan syndrome. Nat Genet. 2007 Aug;39(8):1013-7.
Romano AA, Allanson JE, Dahlgren J, Gelb BD, Hall B, Pierpont ME, Roberts AE, Robinson W, Takemoto CM, Noonan JA. Noonan syndrome: clinical features,diagnosis, and management guidelines. Pediatrics. 2010 Oct;126(4):746-59. doi:10.1542/peds.2009-3207.
Yokoyama T, Takano K, Yoshida A, Katada F, Sun P, Takenawa T, Andoh T, Endo T.DA-Raf1, a competent intrinsic dominant-negative antagonist of the Ras-ERKpathway, is required for myogenic differentiation. J Cell Biol. 2007 Jun4;177(5):781-93.