ACTA2 (actin alpha 2) is an
actin protein with several aliases including alpha-actin, alpha-actin-2, aortic smooth muscle or alpha smooth muscle actin (α-SMA, SMactin, alpha-SM-actin, ASMA).
Actins are a
family of
globular multi-functional
proteins that form
microfilaments. ACTA2 is one of 6 different actin
isoforms and is involved in the
contractile apparatus of
smooth muscle
Smooth muscle is an involuntary non- striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit ...
. ACTA2 (as with all the actins) is extremely
highly conserved
In evolutionary biology, conserved sequences are identical or similar sequences in nucleic acids ( DNA and RNA) or proteins across species ( orthologous sequences), or within a genome ( paralogous sequences), or between donor and receptor taxa ( ...
and found in nearly all mammals.
In humans, ACTA2 is encoded by the ''ACTA2''
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
located on 10q22-q24.
Mutations in this gene cause a variety of vascular diseases, such as thoracic aortic disease,
coronary artery disease
Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), myocardial ischemia, or simply heart disease, involves Ischemia, the reduction of blood flow to the myocardium, heart muscle due to build-up o ...
,
stroke,
Moyamoya disease
Moyamoya disease is a disease in which certain arteries in the brain are constricted. Blood flow is blocked by constriction and blood clots ( thrombosis). A collateral circulation develops around the blocked vessels to compensate for the blockage ...
, and
multisystemic smooth muscle dysfunction syndrome
Multisystemic smooth muscle dysfunction syndrome (MSMDS) is a genetic disorder caused by R179 missense mutations in the ACTA2 gene. Initially described as a case report in 1999, it was characterized in 2010 as a syndrome of congenital mydriasis, p ...
.
ACTA2 (commonly referred to as alpha-smooth muscle actin or α-SMA) is often used as a marker of
myofibroblast
A myofibroblast is a cell phenotype that was first described as being in a state between a fibroblast and a smooth muscle cell.
Structure
Myofibroblasts are contractile web-like fusiform cells that are identifiable by their expression of α-sm ...
formation.
Studies have shown that ACTA2 is associated with TGF β pathway that enhances contractile properties of Hepatic Stellate Cells leading to liver fibrosis and cirrhosis.
References
Further reading
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External links
GeneReviews/NIH/NCBI/UW entry on Thoracic Aortic Aneurysms and Aortic Dissections*
Human proteins
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