Degree Type

Dissertation

Date of Award

2001

Degree Name

Doctor of Philosophy

Department

Zoology and Genetics

Major

Molecular, Cellular, and Developmental Biology

First Advisor

Kristen M. Johansen

Second Advisor

Jorgen Johansen

Abstract

The Drosophila JIL-1 tandem Ser/Thr kinase is associated with chromosomes/chromatin throughout the cell cycle in early embryos and localized to hundreds of sites on the open interband regions on third instar larvae polytene chromosomes. Interestingly, the level of JIL-1 is upregulated on the male X chromosome, which is hypertranscribed for dosage compensation. The distribution of JIL-1 overlaps with that of MSL (male specific lethal) proteins and JIL-1 is associated with the MSL complex.;To further study the function of JIL-1 in vivo, a series of JIL-1 mutants from hypomorphs to null were generated. Analyzing the phenotypes of JIL-1 mutants, we found that JIL-1 is required for the viability of both females and males. Moreover, in the surviving flies of JIL-1 hypomorphic mutants, the number of males is less than that of females, implicating that JIL-1 plays a role in dosage compensation. JIL-1 is also required during early embryonic development and for the maintenance of normal higher order polytene chromosome structure in third instar larvae.;Our studies also showed that JIL-1 is involved in the histone H3 Ser10 phosphorylation signaling pathway. The JIL-1 immunocomplex can phosphorylate the Ser10 site in a synthetic H3 N-terminal peptide in vitro. In vivo, Ser10 phosphorylation levels in the third instar larvae of JIL-1 mutants are dramatically reduced. In addition, the decreased H3 Ser10 phosphorylation level can be restored with a GFP-JIL-1 transgene. Moreover, the phosphorylated H3 Ser10 is elevated and colocalized with JIL-1 on the male X chromosome.;Thus, our data suggest a model whereby JIL-1 is involved in a signaling pathway that regulates histone H3 Ser10 phosphorylation in D. melanogaster , which is required to maintain the appropriate higher order chromatin structure to facilitate chromatin functions, such as gene expression, dosage compensation, and so on.

DOI

https://doi.org/10.31274/rtd-180813-1571

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu

Copyright Owner

Yanming Wang

Language

en

Proquest ID

AAI3016753

File Format

application/pdf

File Size

114 pages

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