Epigenetičko utišavanje kromosoma X

undergraduate thesis

• Title (english): Epigenetics silencing of X chromosome
• Author: Mihaela Tremski
• Mentor: Vlatka Zoldoš (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2012, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Kromosomske razlike među spolovima dovode do neravnoteže genskih produkata između mužjaka (XY) i ženke (XX) sisavaca. Za uspostavu ravnoteže genskog produkta X kromosoma, tj. kompenzaciju doze kod sisavaca, neophodan je mehanizam epigenetičkog utišavanja ekspresije gena na X kromosomu. Postoje dva načina regulacije utišavanja – nasumična inaktivacija i inaktivacija mehanizmom genomskog utiska. Proces epigenetičkog utišavanja događa se kroz inicijaciju, širenje i održavanje inaktivnog stanja X kromosoma. Tijekom inicijacije dolazi do ekspresije gena s Xic regije, čiji produkt je duga nekodirajuća RNA molekula Xist, određivanja broja i odabir X kromosoma koji će biti utišan. U utišavanju kromosoma X sudjeluje nekoliko slojeva epigenetičkih događaja koji se događaju sekvencijalno: oblaganje kromosoma molekulom Xist, uspostavljanje karakterističnih histonskih modifikacija za utišano kromatinsko stanje, zamjena histona H2A sa specifičnom varijantom makroH2A te metilacija DNA. U ovom radu ukratko je predstavljen proces utišavanja X kromosoma djelovanjem različitih epigenetičkih promjena. Brojni mehanizmi i danas su nepoznati, te su potrebna daljnja istraživanja u tom smjeru.

Abstract (english)

Chromosomal differences between the sexes lead to an imbalance of gene products between males (XY) and females (XX). Dosage compensation mechanisms evolved in mammals in order to establish a balance of gene products of X chromosome in the two sexes. There are two model of X inactivation – random and imprinted X inactivation. The process of epigenetic silencing occurs through the initiation, expansion and maintenance of the inactive X chromosome state. During the initiation process three steps are important: counting, choice of X chromosome to be inactivated and expression of Xic gene in X-chromosome to be inactivate. Xist RNA molecule covers the whole X-chromosome. Then, several layers of epigenetic modifications, specific for inactivated X-chromosome, occur subsequently: establishment of histon modifications associated with repressive chromatin state, incorporation of histone variant macroH2A, and finaly DNA methylation, an epigenetic event that maintain heterochromatic state. In this short review I present epigenetic processes associated with X chromosome silencing process. Many mechanisms are yet to be elucidated, and further research is needed in this direction.

• Keywords: epigenetičko utišavanje; X kromosom
• Keywords (english): epigenetics silencing; X chromosome
• Language: croatian
• URN:NBN: urn:nbn:hr:217:149044
• Study programme: Title: Molecular Biology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-04-20 11:50:08