X-chromosome upregulation and inactivation: two sides of the dosage compensation mechanism in mammals

• Published in: BioEssays Vol. 31; no. 1; pp. 21 - 28
• Main Authors: Dementyeva, Elena V, Shevchenko, Alexander I, Zakian, Suren M
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley-VCH Verlag 2009; WILEY-VCH Verlag; WILEY‐VCH Verlag
• Subjects: Animals; Chromosomes, Human, X; dosage compensation; Dosage Compensation, Genetic; Evolution, Molecular; Female; Gene Expression Regulation; Humans; Male; mammals; Mammals - genetics; Oligonucleotide Array Sequence Analysis; Oocytes - metabolism; Rats; Spermatogenesis; Up-Regulation; X Chromosome Inactivation; X-chromosome; X-inactivation; X-upregulation
• ISSN: 0265-9247; 1521-1878
• DOI: 10.1002/bies.080149

Mammals have a very complex, tightly controlled, and developmentally regulated process of dosage compensation. One form of the process equalizes expression of the X-linked genes, present as a single copy in males (XY) and as two copies in females (XX), by inactivation of one of the two X-chromosomes in females. The second form of the process leads to balanced expression between the X-linked and autosomal genes by transcriptional upregulation of the active X in males and females. However, not all X-linked genes are absolutely balanced. This review is focused on the recent advances in studying the dosage compensation phenomenon in mammals.