title: Functional redundancy and nonredundancy between two Troponin C isoforms inDrosophilaadult muscles.
abstract: We investigated the functional overlap of two muscle Troponin C (TpnC) genes that are expressed in the adult fruit fly,Drosophila melanogaster:TpnC4is predominantly expressed in the indirect flight muscles (IFMs), whereasTpnC41Cis 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 ofTpnC41Cand compared its phenotype to a line lacking functionalTpnC4We 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 inDrosophila.
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131.|Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, GA 30144.
authors.forename: Maria B
authors.initials: MB
authors.lastname: Chechenova
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131.
authors.forename: Sara
authors.initials: S
authors.lastname: Maes
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131.
authors.forename: Sandy T
authors.initials: ST
authors.lastname: Oas
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131.
authors.forename: Cloyce
authors.initials: C
authors.lastname: Nelson
authors.affiliation: Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, GA 30144.
authors.forename: Kaveh G
authors.initials: KG
authors.lastname: Kiani
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131.|Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, GA 30144.
authors.forename: Anton L
authors.initials: AL
authors.lastname: Bryantsev
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131 rcripps@unm.edu.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Cripps
mesh_terms: D000818:Animals; D004331:Drosophila melanogaster / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D009132:Muscles / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism; D019209:Troponin C / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*
chemical_list: D020033:Protein Isoforms; D019209:Troponin C