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CYP27A1 is a
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 ...
encoding a
cytochrome P450 oxidase Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compo ...
, and is commonly known as sterol 27-hydroxylase. This enzyme is located in many different tissues where it is found within the mitochondria. It is most prominently involved in the biosynthesis of bile acids.


Function

CYP27A1 participates in the degradation of
cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...
to bile acids in both the classic and acidic pathways. It is the initiating enzyme in the acidic pathway to bile acids, yielding
oxysterol An oxysterol is a derivative of cholesterol obtained by oxidation involving enzymes and / or pro-oxidants. Such compounds play important roles in various biological processes such as cholesterol homeostasis, lipid metabolism (sphingolipids, fatty ...
s by introducing a
hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydro ...
group to the carbon at the 27 position in
cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...
. In the acidic pathway, it produces 27-hydroxycholesterol from cholesterol whereas in the classic or neutral pathway, it produces 3β-hydroxy-5-cholestenoic acid. While CYP27A1 is present in many different tissues, its function in these tissues is largely uncharacterized. In
macrophages Macrophages (abbreviated as M φ, MΦ or MP) ( el, large eaters, from Greek ''μακρός'' (') = large, ''φαγεῖν'' (') = to eat) are a type of white blood cell of the immune system that engulfs and digests pathogens, such as cancer ce ...
, 27-hydroxycholesterol generated by this enzyme may be helpful against the production of inflammatory factors associated with cardiovascular disease.


Clinical significance

Mutations in CYP27A1 are associated with
cerebrotendineous xanthomatosis Cerebrotendinous xanthomatosis, also called cerebral cholesterosis, is an autosomal recessive form of xanthomatosis. It falls within a group of genetic disorders called the leukodystrophies. Presentation An inherited disorder associated with the ...
, a rare
lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids includ ...
storage disease. Inhibitors of CYP27A1 may be effective as
adjuvants In pharmacology, an adjuvant is a drug or other substance, or a combination of substances, that is used to increase the efficacy#Pharmacology, efficacy or Potency (pharmacology), potency of certain drugs. Specifically, the term can refer to: * Adju ...
in the treatment of ER-positive
breast cancer Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or a r ...
due to inhibition of the production of 27-hydroxycholesterol (which has
estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...
ic actions and stimulates the growth of ER-positive breast cancer cells). Some marketed drugs that have been identified as CYP27A1 inhibitors include
anastrozole Anastrozole, sold under the brand name Arimidex among others, is a medication used in addition to other treatments for breast cancer. Specifically it is used for hormone receptor-positive breast cancer. It has also been used to prevent breast ca ...
, fadrozole,
bicalutamide Bicalutamide, sold under the brand name Casodex among others, is an antiandrogen medication that is primarily used to treat prostate cancer. It is typically used together with a gonadotropin-releasing hormone (GnRH) analogue or surgical remo ...
,
dexmedetomidine Dexmedetomidine, sold under the trade name Precedex among others, is a drug used in humans for sedation. Veterinarians use dexmedetomidine for similar purposes in treating cats, dogs, and horses. It is also used in humans to treat acute agitation ...
, ravuconazole, and
posaconazole Posaconazole, sold under the brand name Noxafil among others, is a triazole antifungal medication. It was approved for medical use in the United States in September 2006, and is available as a generic medication. Medical uses Posaconazole is u ...
.


Interactive pathway map


See also

*
Steroidogenic enzyme __NOTOC__ Steroidogenic enzymes are enzymes that are involved in steroidogenesis and steroid biosynthesis. They are responsible for the biosynthesis of the steroid hormones, including sex steroids (androgens, estrogens, and progestogens) and cortic ...
* CYP27 family


References


Further reading

* * * * * * * * * * * * * * * * * * *


External links


GeneReviews/NCBI/NIH/UW entry on Cerebrotendinous Xanthomatosis
* * {{Use dmy dates, date=April 2017 27