Implications of the gene balance hypothesis for dosage compensation
James A. BIRCHLER , Lin SUN , Ryan DONOHUE , Abhijit SANYAL , Weiwu XIE
Front. Biol. ›› 2011, Vol. 6 ›› Issue (2) : 118 -124.
Implications of the gene balance hypothesis for dosage compensation
Dosage compensation refers to the equal expression between the sexes despite the fact that the dosage of the X chromosome is different in males and females. In BoldItalic there is a twofold upregulation of the single male X. In triple X metafemales, there is also dosage compensation, which occurs by a two-thirds downregulation. There is a concomitant reduction in expression of many autosomal genes in metafemales. The male specific lethal (MSL) complex is present on the male X chromosome. Evidence is discussed showing that the MSL complex sequesters a histone acetyltransferase to the X chromosome to mute an otherwise increased expression by diminishing the histone acetylation on the autosomes. Several lines of evidence indicate that a constraining activity occurs from the MSL complex to prevent overcompensation on the X that might otherwise occur from the high level of acetylation present. Together, the evidence suggests that dosage compensation is a modification of a regulatory inverse dosage effect that is a reflection of intrinsic gene regulatory mechanisms and that the MSL complex has evolved in reaction in order to equalize the expression on both the X and autosomes of males and females.
inverse dosage effect / male specific lethal complex / histone acetylation / metafemales
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Higher Education Press and Springer-Verlag Berlin Heidelberg
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