X-chromosome inactivation pattern in human extra-embryonic tissue

• Grant number: 06/05382-5
• Support Opportunities: Scholarships in Brazil - Master
• Start date: March 01, 2007
• End date: February 28, 2009
• Field of knowledge: Biological Sciences - Genetics - Human and Medical Genetics
• Principal Investigator: Lygia da Veiga Pereira
• Grantee: Joana Carvalho Moreira de Mello
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

In mammals, X chromosome inactivation (XCI) is the transcriptional silencing of all but one X present in female normal somatic cells. This process ensures dosage compensation for X-linked genes among females (XX) and males (XY).There are two XCI patterns: random, where in each cell the Xi (inactive X) is chosen by chance; or imprinted, where the X chromosome activity depends on parental origin.In marsupial female embryonic cells inactivation is imprinted and the Xp chromosome is always the inactive one in all cells. In contrast, in embryonic cells of euterian mammals, either the paternal or the maternal X chromosome is randomly inactivated. On the other hand, in mice and bovines, the extra embryonic tissues, derived from the trophoblasts cells, have an imprinted pattern, a process similar to the marsupials where the Xp is inactivated in all cells.The XCI of extra-embryonic human tissues have been widely studied since the second half of the past century. Nonetheless, these researches have focused on the expression of only one or two X-linked genes and, sometimes, on human-mouse hybrid cells, generating conflicting results. The use of analyses of X-linked expressed single nucleotide polymorphisms (cSNPs) make it possible to investigate single alleles-specific expression patterns of a larger gamut of genes present along the X chromosome, generating a more representative panorama of the XCI in extra-embryonic human tissues.

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

MELLO, Joana Carvalho Moreira de. X-chromosome inactivation pattern in human extra-embryonic tissue. 2010. Master's Dissertation - Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) São Paulo.