background:
Hairless is a 1,189 amino acid protein which is expressed as two isoforms produced by alternative splicing. The two isoforms are expressed in a variety of tissues in varying concentrations. Isoform 1 is more abundant than isoform 2 and is expressed at low levels in kidneys and testis, while isoform 2 is expressed abundantly in skin. Both isoforms are also present together in many tissues and are expressed strongly in small intestine and brain and weakly in trachea. HR is thought to be a transcription factor involved in hair growth. Hair growth occurs in three phases known as anagen, catagen and telogen, which are phases where growth, regression and rest, respectively, are taking place. By unknown mechanisms, HR is thought to regulate one of the hair growth phases and to work with vitamin D receptor (VDR) to regulate hair follicle cycling. Defects in HR may cause two serious ailments, known as alopecia universalis congenita (ALUNC) and atrichia with papular lesions (APL), which is also referred to as congenital atrichia. Both are autosomally recessive impairments. ALUNC is a rare condition in which hair follicles are produced without hair, while APL is a serious disease in which papillary lesions may cover the body and little to no hair is grown.
Function:
May act as a transcription factor that could act on to regulate one of the phases of hair growth.
Subcellular Location:
Nucleus.
Tissue Specificity:
Strongest expression of isoforms 1 and 2 is seen in the small intestine, weaker expression in brain and colon, and trace expression is found in liver, pancreas, spleen, thymus, stomach, salivary gland, appendix and trachea. Isoform 1 is always the most abundant. Isoform 1 is exclusively expressed at low levels in kidney and testis. Isoform 2 is exclusively expressed at high levels in the skin.
DISEASE:
Defects in HR are the cause of alopecia universalis congenita (ALUNC) [MIM:203655]. ALUNC is a rare autosomal recessive form of hair loss characterized by hair follicles without hair.
Defects in HR are the cause of atrichia with popular lesions (APL) [MIM:209500]; also known as congenital atrichia. APL is an autosomal recessive disease characterized by papillary lesions over most of the body and almost complete absence of hair.
Defects in HR are the cause of hypotrichosis type 4 (HYPT4) [MIM:146550]. An autosomal dominant condition characterized by reduced amount of hair, alopecia, little or no eyebrows, eyelashes or body hair, and coarse, wiry, twisted hair in early childhood.
Similarity:
Contains 1 JmjC domain.
Database links:
UniProtKB/Swiss-Prot: O43593.5
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
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