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. 2019 Nov 20;8:e50496. doi: 10.7554/eLife.50496

Figure 1. Aggregate formation upon Zasp overexpression.

(A–H) Confocal images of IFM in control or Zasp overexpression conditions using Act88F-Gal4; actin filaments are marked in magenta and Z-discs in green. (A) In control flies, sarcomeres are regular with Z-discs located in the center of the actin signal. (B) Upon GFP-Zasp52-PR overexpression sarcomere structure is severely affected and big Zasp aggregates appear. (C) The overexpression of Flag-Zasp52-PP, an isoform lacking all LIM domains, has a modest sarcomere phenotype and aggregation is not observed. (D) Overexpression of a mutated form of Zasp52-PR with a deletion in the ZM domain does not form aggregates. (E) Overexpression of a mutated form of Zasp52-PR carrying a deletion in the PDZ domain causes small aggregates and sarcomere phenotypes. (F and G) The overexpression of the other Zasp paralogs, Zasp66 or Zasp67, does not cause aggregates. (H) Overexpression of GFP-Zasp52-PK, a smaller isoform of Zasp52 lacking LIM2, 3, and 4 domains affects sarcomere structure, but aggregation is infrequent. (I) Estimation of Z-disc aggregates in all overexpression conditions, n = 10 muscle fibers. (J) Confocal images of IFM in control or in mild overexpression of GFP-Zasp52-PR using UH3-Gal4. (K) Estimation of Z-disc aggregates in mild overexpression of GFP-Zasp52-PR. (L) Frequency plot of Z-disc sizes. Z-discs are bigger when GFP-Zasp52-PR is overexpressed using UH3-Gal4. Scale bars, 10 µm. p-Values in panel I and K were calculated using Welch’s two-sample t-test.

Figure 1—source data 1. Aggregate frequency estimates in Zasp overexpressions.

Figure 1.

Figure 1—figure supplement 1. Differences in Zasp isoforms.

Figure 1—figure supplement 1.

Cartoon of selected Zasp protein isoforms with annotated protein domains. Isoforms are named according to FlyBase. Numbers at each end represent the length in amino acids. ZM, Zasp-like motif.
Figure 1—figure supplement 2. Zasp-mediated aggregation depends only partially on α-actinin.

Figure 1—figure supplement 2.

(A, B) Confocal images of IFM in control or α-actinin depleted conditions; actin filaments are marked in magenta and Z-discs marked by Zasp66-GFP are shown in green. (A) Control sarcomeres are regular with Z-discs located in the center of the actin signal. (B) In α-actinin-depleted muscles sarcomere structure is severely perturbed, and Z-discs are rarely visible. (C, D) Confocal images of IFM with aggregates caused by the overexpression of Zasp52-PR. (C) Overexpression of Zasp52-PR produces aggregates. (D) Overexpression of Zasp52-PR in α-actinin-depleted muscles produces smaller aggregates. (E) Estimation of Z-disc aggregates in all overexpression conditions, n = 10 muscle fibers. Act88F-Gal4 was used in all panels. Scale bars, 10 µm. p-Values in panel E were calculated using Welch’s two-sample t-test.