Eukaryotic organisms employ epigenetic regulatory systems that are essential for genome stability and gene expression. Disruptions in these systems are associated with a wide range of pathologies, including chromosome instability, birth defects, cancer and developmental abnormalities. An intriguing type of epigenetic regulation, X chromosome dosage compensation, adjusts the expression of X-linked genes in one sex to accommodate the different numbers of X chromosomes in males and females. Dosage compensation has been intensively studied in mice, C. elegans and Drosophila. The striking differences in the compensation strategies of these organisms are usually emphasized. However, all three systems rely on regulatory complexes that are selectively recruited to X chromatin to modulate expression. These complexes, and their actions on chromatin, have been studied in detail. But in no case do we understand how X chromatin is identified with the requisite selectivity. Our long-term goal is to understand how an entire chromosome is identified and regulated. We have found that the siRNA pathway, and siRNAs from a repetitive element that is near-exclusive to the X, promote recognition of X chromatin. Strikingly, one of these elements, when placed on an autosome, recruits compensation to flanking autosomal genes. These elements are candidate matrix attachment regions and participate in long range interactions. The specific hypothesis we will test is that X chromosome recognition in Drosophila is guided by a chromosome-specific architecture, determined by repetitive elements and modulated by the siRNA pathway. This arrangement facilitates spreading of compensation along the chromosome. We propose that this acts cooperatively with well-studied sites that recruit the dosage compensation complex directly. The proposed experiments will 1) establish the role of the siRNA in modification of chromatin at the X-linked repeats, 2) determine the dependence of matrix attachment and long range interactions on these modifications and 3) test the idea that an X-linked locus containing a key member of the dosage compensation complex, as well as X-specific repeats, acts to coordinate epigenetic modification during compensation.

Public Health Relevance

Proper regulation of the genome requires coordinated control of groups of genes as large as an entire chromosome. This proposal will investigate the idea that small RNA modulates the architecture of the fly X chromosome to facilitate coordinated regulation of the genes on this chromosome. The similarities between analogous processes in flies and mammals suggest that similar mechanisms contribute to normal genome regulation in humans.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM093110-07
Application #
9552182
Study Section
Molecular Genetics B Study Section (MGB)
Program Officer
Carter, Anthony D
Project Start
2011-01-01
Project End
2020-08-31
Budget Start
2018-09-01
Budget End
2019-08-31
Support Year
7
Fiscal Year
2018
Total Cost
Indirect Cost
Name
Wayne State University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
001962224
City
Detroit
State
MI
Country
United States
Zip Code
48202
Deshpande, Nikita; Meller, Victoria H (2018) Chromatin That Guides Dosage Compensation Is Modulated by the siRNA Pathway in Drosophila melanogaster. Genetics 209:1085-1097
Joshi, Sonal S; Meller, Victoria H (2017) Satellite Repeats Identify X Chromatin for Dosage Compensation in Drosophila melanogaster Males. Curr Biol 27:1393-1402.e2
Meller, Victoria H; Joshi, Sonal S; Deshpande, Nikita (2015) Modulation of Chromatin by Noncoding RNA. Annu Rev Genet 49:673-95
Menon, Debashish U; Meller, Victoria H (2015) Identification of the Drosophila X chromosome: The long and short of it. RNA Biol 12:1088-93
Koya, S Kiran; Meller, Victoria H (2015) Modulation of Heterochromatin by Male Specific Lethal Proteins and roX RNA in Drosophila melanogaster Males. PLoS One 10:e0140259
Apte, Manasi S; Moran, Victoria A; Menon, Debashish U et al. (2014) Generation of a useful roX1 allele by targeted gene conversion. G3 (Bethesda) 4:155-62
Menon, Debashish U; Coarfa, Cristian; Xiao, Weimin et al. (2014) siRNAs from an X-linked satellite repeat promote X-chromosome recognition in Drosophila melanogaster. Proc Natl Acad Sci U S A 111:16460-5
Deshpande, Nikita; Meller, Victoria H (2014) Sex chromosome evolution: life, death and repetitive DNA. Fly (Austin) 8:197-9
Joshi, Sonal S; Cheong, Han; Meller, Victoria H (2014) A strategy for generation and balancing of autosome: Y chromosome translocations. Fly (Austin) 8:58-62
Menon, Debashish U; Meller, Victoria H (2012) A role for siRNA in X-chromosome dosage compensation in Drosophila melanogaster. Genetics 191:1023-8

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