IGSF1

IGSF1
Identifiers
Aliases	IGSF1, CHTE, IGCD1, IGDC1, INHBP, PGSF2, p120, immunoglobulin superfamily member 1
External IDs	MGI: 2147913 HomoloGene: 1195 GeneCards: IGSF1
Gene ontology Molecular function • inhibin binding • protein binding • coreceptor activity • receptor activity Cellular component • integral component of membrane • extracellular region • membrane Biological process • regulation of transcription, DNA-templated • signal transduction Sources:Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	3547	209268
Ensembl	ENSG00000147255	ENSMUSG00000031111
UniProt	Q8N6C5	Q7TQA1
RefSeq (mRNA)	NM_001170961 NM_001170962 NM_001170963 NM_001555 NM_205833	NM_177591 NM_177915 NM_183335 NM_183336
RefSeq (protein)	NP_001164432.1 NP_001164433.1 NP_001164434.1 NP_001546.2 NP_991402.1	NP_808259.2 NP_808583.1 NP_899178.2 NP_899179.1
Location (UCSC)	Chr X: 131.27 – 131.58 Mb	Chr X: 49.78 – 49.8 Mb
PubMed search	[1]	[2]
Wikidata

Immunoglobulin superfamily, member 1^[3] is a plasma membrane glycoprotein encoded by the IGSF1 gene,^[4][5][6] which maps to the X chromosome in humans and other mammalian species.

Function

IGSF1’s function in normal cells is unresolved. The protein is a member of the immunoglobulin (Ig) superfamily. It was predicted to contain 12 Ig loops, a transmembrane domain, and a short cytoplasmic tail. However, during translation of the protein, it is cleaved into amino- and carboxy-terminal domains (NTD and CTD, respectively).^[7] Only the CTD is trafficked to the plasma membrane. The NTD is trapped within the endoplasmic reticulum (ER). Pathogenic mutations in the IGSF1 gene block the transport of the CTD to the plasma membrane.

Clinical Relevance

Mutations in IGSF1 cause a condition called IGSF1 deficiency syndrome^[8] or central hypothyroidism/testicular enlargement (CHTE^[9]). The condition, which affects an estimated 1:100,000 people,^[10] is more common in males than females. Most affected males are discovered through neonatal screening for hypothyroidism. The extent of hypothyroidism is variable, but most male cases require treatment with thyroid hormone replacement. Males with IGSF1 deficiency exhibit enlarged testicles (also known as macroorchidism) and a delay in the development of secondary sexual characteristics. Post-pubertally, there is no evidence of impaired fertility in these men.

The IGSF1 gene is also active in the brain and in the developing liver. It can also become reactivated in liver cancer (hepatocellular carcinoma).^[11]

Animal Model

Mice lacking a functional Igsf1 gene similarly exhibit hypothyroidism of central origin.^[8] The IGSF1 gene is particularly active in the pituitary gland. The pituitary synthesizes and secretes thyroid-stimulating hormone (TSH). TSH, in turn, stimulates production of the thyroid hormones, thyroxine and triiodothyronine, by the thyroid gland. TSH secretion is controlled by thyrotropin-releasing hormone (TRH), which is released by neurons in the hypothalamus of the brain. In Igsf1 deficient mice, the receptor for TRH is downregulated in the pituitary.^[8] This decrease could explain, at least in part, the central hypothyroidism observed in both humans and mice with IGSF1 deficiency. How the loss of IGSF1 causes a decrease in TRH receptors is presently unknown.

References

Further reading