This report describes fly models relevant to cardiomyopathies that are TNNI3-related. The human gene implicated in these diseases (TNNI3) encodes cardiac-type troponin I, a component of sarcomere thin filaments. TNNI3 is implicated in several forms of heart disease (see MIM:191044), including CMD1FF (FBhh0000166), CMD2A (FBhh0000165), CMH7 (FBhh0000415), and familial restrictive cardiomyopathy 1 (MIM:115210). Involvement of TNNI3 with hypertrophic cardiomyopathy is strongly supported by a large-scale WES analysis (Walsh, et al., 2016; pubmed:27532257).
A UAS construct of a tagged wild-type human Hsap\TNNI3 gene has been introduced into flies and has been made available; it has not been characterized.
There is one fly ortholog of TNNI3, wupA; Dmel\wupA is also orthologous to human genes TNNI1 and TNNI2, which are described as skeletal-type troponins. Multiple genetic reagents have been been generated for the wupA gene including classical loss-of-function alleles, RNAi targeting constructs, and alleles caused by insertional mutagenesis. Homozygous loss-of-function alleles are lethal in the embryonic stage. A well-characterized missense mutation that survives to adulthood exhibits multiple defects in heart function, indirect flight muscle hypercontraction, and other muscle defects. Genetic and physical interactions of Dmel\wupA have been described; see below and the wupA gene report.
[updated Apr. 2018 by FlyBase; FBrf0222196]
The troponin complex is located on the thin filament of striated muscle and is composed of 3 component polypeptides: troponin I (TNNI1, MIM:191042; TNNI2, MIM:191043; and TNNI3, OMIM), troponin T (TNNT1, MIM:191041; and TNNT2, MIM:191045), and troponin C (TNNC1, MIM:191040; and TNNC2 MIM:191039). [From MIM:191044; 2016.02.02]
Many to one: 3 human to 1 Drosophila; additional human orthologs are TNNI1 and TNNI2. TNNI3 is described as cardiac-type I troponin; TNNI1 and TNNI2 are described as skeletal-type I troponins.
Ortholog of human TNNI1, TNNI2, and TNNI3 (1 Drosophila to 3 human). Dmel\wupA shares 31-34% identity and 50-55% similarity with the human genes.