Sandbox Reserved 1120: Difference between revisions
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==History== | ==History== | ||
After centuries of unfounded theories mainly based on environmental factors, the first molecular theory concerning the sex determination appeared in 1891. At this time, the german biologist Hermann Henking was studying sperm formation in wasps. As a chromosome which was not present in all the wasps looked different from the others, he suspected it to play a role in sex determination and called it the "X chromosome". | |||
Ten years later, Clarence Erwin McClung saw that this chromosome behaved differently during the meiosis and was only present in half the sperm cells of grasshoppers. As the main characteristic that varies in 50/50 proportions among zygotes is the sex, McClung suspected the X chromosome to be implicated in sexual development. | Ten years later, Clarence Erwin McClung saw that this chromosome behaved differently during the meiosis and was only present in half the sperm cells of grasshoppers. As the main characteristic that varies in 50/50 proportions among zygotes is the sex, McClung suspected the X chromosome to be implicated in sexual development. | ||
In 1905, Nettie Stevens discovered the "Y chromosome" (and the female XX and male XY patterns) while she was counting the chromosomes of beetles under the microscope<ref>Sumner, A. T. Sex Chromosomes and Sex Determination. Chromosomes: Organization and Function, 97-108. [http://www.nature.com/scitable/nated/topicpage/Sex-Chromosomes-and-Sex-Determination-44565]</ref>. | In 1905, Nettie Stevens discovered the "Y chromosome" (and the female XX and male XY patterns) while she was counting the chromosomes of beetles under the microscope<ref>Sumner, A. T. Sex Chromosomes and Sex Determination. Chromosomes: Organization and Function, 97-108. [http://www.nature.com/scitable/nated/topicpage/Sex-Chromosomes-and-Sex-Determination-44565]</ref>. | ||
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===Generality=== | ===Generality=== | ||
The SRY gene encodes the SRY protein. The SRY protein is a transcriptional factor inducing the male phenotype in embryo. The SRY gene is located on the [https://en.wikipedia.org/wiki/Y_chromosome Y chromosom] in the short arm (p) 11.3 <ref>[http://www.ncbi.nlm.nih.gov/gene/6736]</ref>. This gene has only one exon containing the HMG domain (DNA-binding high-mobility group box domain). That's means that SRY mRNA does not have a alternative splicing, so there is one isoform of SRY protein.<ref> McElreavey K, Barbaux S, Ion A, Fellous M. The genetic basis of murine and human sex determination: a review. Heredity. 1995 Dec;75 ( Pt 6):599–611. [http://www.ncbi.nlm.nih.gov/pubmed/8575930]</ref>. Moreover,the human genome contains one copy of the SRY gene, whereas the mouse genome contains 6 copy of this gene. <ref> Sekido R, Lovell-Badge R. Genetic control of testis development. Sex Dev Genet Mol Biol Evol Endocrinol Embryol Pathol Sex Determ Differ. 2013;7(1-3):21–32 </ref> | |||
===Sequence of the SRY gene=== | ===Sequence of the SRY gene=== | ||
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===Regulation of the expression of the SRY gene=== | ===Regulation of the expression of the SRY gene=== | ||
In humans, the SRY promoter is found at −408 bp to −95 bp upstream of the ATG initiation codon. Moreover, the SRY gene has enhancers at -727 pb upstream of the ATG initiation codon. The linkage between regulatory proteins and this enhancers have the property to increase the production of SRY protein. These regulatory proteins could be: SF1 (steroidogenic factor 1), SP1 and WT 1 (Wilms tumor). <ref>Harley VR, Clarkson MJ, Argentaro A. The Molecular Action and Regulation of the Testis-Determining Factors, SRY (Sex-Determining Region on the Y Chromosome) and SOX9 [SRY-Related High-Mobility Group (HMG) Box 9]. Endocr Rev. 2003 Aug 1;24(4):466–87. [http://press.endocrine.org/doi/10.1210/er.2002-0025?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed&]</ref> | |||
*SF1: this transcriptional factor belong to the family of nuclear hormone receptor and contains a zinc finger. The activation of this protein requires a ligand (hormone). | *SF1: this transcriptional factor belong to the family of nuclear hormone receptor and contains a zinc finger. The activation of this protein requires a ligand (hormone). | ||
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:It has been shown that SRY would be involved in the regulation of the renin-angiotensin system in mice. Indeed, sequence mutations of the protein lead to hypertension. | :It has been shown that SRY would be involved in the regulation of the renin-angiotensin system in mice. Indeed, sequence mutations of the protein lead to hypertension. | ||
Because the human's SRY organisation is very closed to he mouse's, it has been proposed that SRY would have the same function in human but it has not been studied directly.<ref>PMID: | Because the human's SRY organisation is very closed to he mouse's, it has been proposed that SRY would have the same function in human but it has not been studied directly.<ref>PMID:22315667</ref> | ||
== Disease == | == Disease == | ||
