Indian hedgehog homolog (Drosophila), also known as IHH, is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

which in humans is encoded by the ''IHH''

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 ba ...

. This

cell signaling In biology, cell signaling (cell signalling in British English) or cell communication is the ability of a cell to receive, process, and transmit signals with its environment and with itself. Cell signaling is a fundamental property of all cellula ...

protein is in the

hedgehog signaling pathway The Hedgehog signaling pathway is a signaling pathway that transmits information to embryonic cells required for proper cell differentiation. Different parts of the embryo have different concentrations of hedgehog signaling proteins. The pathwa ...

. The several mammalian variants of the ''

Drosophila ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species ...

'' hedgehog gene ( which was the first named) have been named after the various species of

hedgehog A hedgehog is a spiny mammal of the subfamily Erinaceinae, in the eulipotyphlan family Erinaceidae. There are seventeen species of hedgehog in five genera found throughout parts of Europe, Asia, and Africa, and in New Zealand by introducti ...

; the

Indian hedgehog The Indian hedgehog (''Paraechinus micropus'') is a species of hedgehog native to India and Pakistan. It mainly lives in sandy desert areas but can be found in other environments. Description The Indian hedgehog can be compared to the long-ear ...

is honored by this one. The gene is not specific to Indian hedgehogs.

Function

The Indian hedgehog protein is one of three

s in the

mammalian Mammals () are a group of vertebrate animals constituting the class (biology), class Mammalia (), characterized by the presence of mammary glands which in Female#Mammalian female, females produce milk for feeding (nursing) their young, a ...

family, the others being

desert hedgehog The desert hedgehog (''Paraechinus aethiopicus'') is a species of mammal in the family Erinaceidae. Basic facts The desert hedgehog is one of the smallest of hedgehogs. It is long and weighs about . The quills (or spines to give their corre ...

(DHH) and

sonic hedgehog Sonic hedgehog protein (SHH) is encoded for by the ''SHH'' gene. The protein is named after the character ''Sonic the Hedgehog''. This signaling molecule is key in regulating embryonic morphogenesis in all animals. SHH controls organogenesis and ...

(SHH). It is involved in

chondrocyte Chondrocytes (, from Greek χόνδρος, ''chondros'' = cartilage + κύτος, ''kytos'' = cell) are the only cells found in healthy cartilage. They produce and maintain the cartilaginous matrix, which consists mainly of collagen and proteog ...

differentiation, proliferation and maturation especially during

endochondral ossification Endochondral ossification is one of the two essential processes during fetal development of the mammalian skeletal system by which bone tissue is produced. Unlike intramembranous ossification, the other process by which bone tissue is produced, c ...

. It regulates its effects by feedback control of parathyroid hormone-related peptide ( PTHrP). Indian Hedge Hog, (Ihh) is one of three signaling molecules from the Hedgehog (Hh) gene family.Ma, G., Yu, J., Xiao, Y. et al. Indian hedgehog mutations causing brachydactyly type A1 impair Hedgehog signal transduction at multiple levels. Cell Res 21, 1343–1357 (2011). https://doi.org/10.1038/cr.2011.76 Genes of the Hh family, Sonic Hedgehog (Shh), Desert Hedgehog (Dhh) and Ihh regulate several fetal developmental processes. The Ihh homolog is involved in the formation of chondrocytes during the development of limbs. The protein is released by small, non-proliferating, mature chondrocytes during endochondral ossification. Recently, Ihh mutations are shown to cause brachydactyly type A1 (BDA1), the first Mendelian autosomal dominant disorder in humans to be recorded.Lodder EM, Hoogeboom AJM, Coert JH, de Graaff E. 2008. Deletion of 1 amino acid in Indian hedgehog leads to brachydactylyA1. Am J Med Genet Part A 146A:2152–2154. doi:10.1002/ajmg.a.32441 There are seven known mutations to Ihh that cause BDA1. Of particular interest, are mutations involving the E95 residue, which is thought to be involved with proper signaling mechanisms between Ihh and its receptors. In a mouse model, mice with mutations to the E95 residue were found to have abnormalities to their digits. Ihh may also be involved in endometrial cell differentiation and implantation. Studies have shown progesterone to upregulate Ihh expression in the murine endometrium, suggesting a role in implantation.Qingxiang Wei, Eric D. Levens, Lilja Stefansson, Lynnette K. Nieman, Indian Hedgehog and Its Targets in Human Endometrium: Menstrual Cycle Expression and Response to CDB-2914, The Journal of Clinical Endocrinology & Metabolism, Volume 95, Issue 12, 1 December 2010, Pages 5330–5337, https://doi.org/10.1210/jc.2010-0637 Ihh is suspected to be involved in the downstream regulation of other signaling molecules that are known to play a role in murine implantation.Kathryn Smith, Redab Alnifaidy, Qingxiang Wei, Lynnette K. Nieman, Endometrial Indian hedgehog expression is decreased in women with endometriosis, Fertility and Sterility, Volume 95, Issue 8, 2011, Pages 2738-2741.e3, ISSN 0015-0282, https://doi.org/10.1016/j.fertnstert.2011.05.018. Mouse models involving Ihh null mice demonstrated failure of attachment and decidualization.

Function

References

Further reading