Functional redundancy and nonredundancy between two Troponin C isoforms in adult muscles
Department
Molecular and Cellular Biology
Document Type
Article
Publication Date
3-15-2017
Abstract
We investigated the functional overlap of two muscle Troponin C (TpnC) genes that are expressed in the adult fruit fly, : is predominantly expressed in the indirect flight muscles (IFMs), whereas is the main isoform in the tergal depressor of the trochanter muscle (TDT; jump muscle). Using CRISPR/Cas9, we created a transgenic line with a homozygous deletion of and compared its phenotype to a line lacking functional We found that the removal of either of these genes leads to expression of the other isoform in both muscle types. The switching between isoforms occurs at the transcriptional level and involves minimal enhancers located upstream of the transcription start points of each gene. Functionally, the two TpnC isoforms were not equal. Although ectopic TpnC4 in TDT muscles was able to maintain jumping ability, TpnC41C in IFMs could not effectively support flying. Simultaneous functional disruption of both TpnC genes resulted in jump-defective and flightless phenotypes of the survivors, as well as abnormal sarcomere organization. These results indicated that TpnC is required for myofibril assembly, and that there is functional specialization among TpnC isoforms in .
Journal Title
Molecular biology of the cell
Volume
28
Issue
6
First Page
760
Last Page
770
Digital Object Identifier (DOI)
10.1091/mbc.E16-07-0498