Cher localizes to the Z-disc in the IFM and is necessary for sarcomere structural stability.

<p><b>(A</b>) <i>cher</i> genomic region showing several transcripts and several protein isoforms that can be grouped based on their molecular weight into 4 groups (CherA-D). Green triangles represent transgenic insertion sites of protein-trap lines, each bearing a splice acceptor site followed by a Venus and a Flag tag. The protein domains encoded by different exons are indicated at the bottom: CH (ABD), calponin homology domain 1 and 2 comprises the actin-binding domain; Ig, immunoglobulin-like domains; DD, dimerization domain. Asterisks denote location of the premature stop point mutants in <i>cher</i>^{<i>Q1042x</i>} and <i>cher</i>^{<i>Q1415sd</i>}. The <i>cher</i>^<i>Δ5</i> deleted region is denoted by a black line (<b>B</b>) Immunoblot from <i>cher</i>^{<i>CPTI1399</i>} thoraces incubated with anti-Flag antibody reveals 4 Cher isoforms, specifically depleted in <i>Mef2-Gal4</i>>UAS-<i>cher-JF</i> RNAi. (<b>C, D</b>) IFM confocal images from heterozygous Flag-tagged Cher traps stained with anti-Flag antibody to visualize the tagged isoforms. In all images, asterisks mark Z-discs of a selected myofibril immediately above the asterisks. (<b>C</b>) All Cher isoforms, revealed by the <i>cher</i>^{<i>CPTI1403</i>} protein trap, localize at the Z-disc. (<b>D</b>) Long Cher isoforms tagged by <i>cher</i>^{<i>CPTI1399</i>} localize to the Z-disc. (<b>E</b>) Quantification of recognizable sarcomeres in control, Cher-depleted, and <i>cher</i> mutant IFM. Statistical significance assessed by one-way ANOVA with post hoc Tukey: n.s. = not significant, ** = P ≤ 0.01, **** = P ≤ 0.0001. (<b>F</b>, <b>G</b>) Confocal images from control and Cher-depleted IFM, stained with anti-Kettin antibody to visualize Z-discs in red and phalloidin to visualize actin thin filaments in green. (<b>F</b>) Regular sarcomeric structure in <i>Mef2-Gal4</i> control flies, (<b>G</b>) Depletion of Cher in <i>Mef2-Gal4</i>, <i>UAS-cher-JF</i> flies results in severe sarcomeric disorganization. Arrowheads indicate reduced actin staining at the Z-disc. Scale bars: 5 μm.