Aberrant Splicing of an Alternative Exon in the Drosophila Troponin-T Gene Affects Flight Muscle Development

Nongthomba, Upendra and Ansari, Maqsood and Thimmaiya, Divesh and Stark, Meg and Sparrow, John (2007) Aberrant Splicing of an Alternative Exon in the Drosophila Troponin-T Gene Affects Flight Muscle Development. In: Genetics, 177 (1). pp. 295-306.

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Abstract

During myofibrillogenesis, many muscle structural proteins assemble to form the highly ordered contractile sarcomere. Mutations in these proteins can lead to dysfunctional muscle and various myopathies. We have analyzed the Drosophila melanogaster troponin T (TnT) $up^1$ mutant that specifically affects the indirect flight muscles (IFM) to explore troponin function during myofibrillogenesis. The $up^1$ muscles lack normal sarcomeres and contain "zebra bodies," a phenotypic feature of human nemaline myopathies. We show that the $up^1$ mutation causes defective splicing of a newly identified alternative TnT exon (10a) that encodes part of the TnT C terminus. This exon is used to generate a TnT isoform specific to the IFM and jump muscles, which during IFM development replaces the exon 10b isoform. Functional differences between the 10a and 10b TnT isoforms may be due to different potential phosphorylation sites, none of which correspond to known phosphorylation sites in human cardiac TnT. The absence of TnT mRNA in $up^1$ IFM reduces mRNA levels of an IFM-specific troponin I (TnI) isoform, but not actin, tropomyosin, or troponin C, suggesting a mechanism controlling expression of TnT and TnI genes may exist that must be examined in the context of human myopathies caused by mutations of these thin filament proteins.

Item Type:	Journal Article
Publication:	Genetics
Publisher:	Genetics Society of America
Additional Information:	Copyright of this article belongs to Genetics Society of America.
Department/Centre:	Division of Biological Sciences > Molecular Reproduction, Development & Genetics
Date Deposited:	19 Nov 2007
Last Modified:	08 Feb 2012 06:21
URI:	http://eprints.iisc.ac.in/id/eprint/12487

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