Degree Type

Dissertation

Date of Award

2004

Degree Name

Doctor of Philosophy

Department

Biochemistry, Biophysics and Molecular Biology

Major

Genetics

First Advisor

Kristen M. Johansen

Second Advisor

Jorgen Johansen

Abstract

JIL-1 encodes a chromatin-associated tandem serine/threonine kinase in Drosophila melanogaster. JIL-1 predominantly associates with interbands on polytene chromosomes. It appears at higher levels on the X chromosome than on autosomes in males, and distributes about equally on all chromosomes in females. In addition, in males JIL-1 overlaps with the MSL (for male specific lethal) complex that specifically associates with the male X chromosome on which expression of most genes are upregulated.;We isolated JIL-1 mutants by inducing imprecise excision of an EP element inserted in JIL-1. We found that JIL-1 is required for viability of both females and males, but male viability is more sensitive to reduction of JIL-1 levels. Additionally, JIL-1 is required for embryogenesis, oogenesis and segment identity. Polytene chromosomes from JIL-1 mutant third instar larvae are shortened, coiled and lose their banding patterns, suggesting that JIL-1 plays a role in maintaining higher order chromatin structure. JIL-1 mutants show reduced levels of histone H3 serine10 (ser10) phosphorylation. The higher level of histone H3 ser10 phosphorylation on the male X chromosome is dependent upon JIL-1. However, the level of histone H3 ser10 phosphorylation in mitotic cells is similar between JIL-1 mutants and wild type, suggesting that JIL-1 mainly controls histone H3 ser10 phosphorylation in interphase.;JIL-1 kinase domain I (KDI) interacts with Lola ZF5, a splice isoform of the lola locus. Most Lola isoforms belong to the class of BTB (for b&barbelow;ric-a-brac, t&barbelow;ramtrack, and B&barbelow;road-complex) domain containing zinc finger proteins while two of them contain no zinc finger motif. A lola P-element mutation potentially disrupting all isoforms partially suppresses the reduced hatch rate phenotype in JIL-1EP(3)3657/JIL-1 EP(3)3657 embryos. The mode of interaction between lola and JIL-1 is consistent with the general nature of BTB zinc finger proteins as transcription repressors, and suggests possible mechanisms through which other proteins can modify JIL-1 functions or JIL-1 regulates other proteins involved in chromatin organization.

DOI

https://doi.org/10.31274/rtd-180813-2110

Publisher

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

Copyright Owner

Weiguo Zhang

Language

en

Proquest ID

AAI3158388

File Format

application/pdf

File Size

149 pages

Share

COinS