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 Drosophila there is a twofold upregulation of the single m...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 Drosophila 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.展开更多
基金supported by National Institutes of Health grant RO1GM068042-05.
文摘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 Drosophila 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.
