Journal: Nature Communications

Article Title: The mitochondrial mRNA-stabilizing protein SLIRP regulates skeletal muscle mitochondrial structure and respiration by exercise-recoverable mechanisms

doi: 10.1038/s41467-024-54183-4

Figure Lengend Snippet: A SLIRP protein content across different wild-type tissues ( n = 3–4, female C57BL/6 J). B SLIRP and LRPPRC protein content in tibialis anterior muscle of Slirp knockout (KO) and littermate wildtype (WT) mice; WT, n = 26; Slirp KO = 35. C SLIRP and LRPPRC protein content in tibialis anterior muscle of WT mice injected with recombinant adeno‐associated virus serotype 6 encoding SLIRP (rAAV6:SLIRP) or rAAV6:eGFP in the contralateral leg as control ( n = 6). D Confocal microscopy of mitochondrial network structure in flexor digitorum brevis muscle fibers of Slirp KO and WT mice ( n = 4, 7–10 fibers per mouse). Corresponding fragmentation index are presented as super plots ; small symbols, each fiber; large symbols, mean of fibers per mouse and color- and symbol-coded for each sex ( ○ male, ◇ female). E TEM images of Slirp KO and WT gastrocnemius muscle ( n = 4; 7–9 fibers per sample). F , G Quantification of percentage of damaged intramyofibrillar (IMF) mitochondria within total mitochondria and relative volume of mitochondria. Small symbols, damaged or total mitochondria per fiber; large identical symbols, average of fibers per biological replicate (female Slirp KO and WT gastrocnemius muscle, n = 4/group). H Mitochondrial respiration in of Slirp KO and WT gastrocnemius muscle (male/female: WT, n = 4/4; Slirp KO, n = 5/5); ○ (blue) male, ◇ (red) female. I Fatty acid oxidation in isolated Slirp KO and WT soleus muscle at rest and in response to contraction (male/female: WT, n = 3/4; Slirp KO, n = 4/8); ○ (blue) male, ◇ (red) female. J RT-qPCR analysis of mitochondrial transcript levels and corresponding immunoblots in gastrocnemius of male Slirp KO and WT mice (mRNA: WT, n = 6; Slirp KO, n = 6; protein: WT, n = 6; Slirp KO, n = 7). K qPCR analysis of mtDNA levels in male Slirp KO and WT mice (WT, n = 6; Slirp KO, n = 7). L , M Climbing assay and life span of control, SLIRP1 and SLIRP2 knockdown flies ( n = 3–9, 10 flies per sample for climbing assay; n = 10, 10 flies per vial for lifespan assay). Data are shown as mean ± SEM, including individual values, where applicable. Geno, main effect of genotype; substrate, main effect of substrate addition; Substrate X Geno, interaction between genotype and substrate; Contraction, main effect of contraction. * p < 0.05, ** p < 0.01, *** p < 0.001, as per Two-tailed Mann Whitney test ( D , F , G ) on average values, Two-way RM ANOVA with Šídák’s multiple comparisons test ( H , I ), Two-tailed unpaired Student´s t test ( J , K ), ordinary one-way ANOVA with Dunnett’s multiple comparisons test ( L ), Log-rank (Mantel-Cox) test ( M ). Source data are provided as a Source Data file.

Article Snippet: The AAV6 vector for SLIRP overexpression and ultra-purified eGFP control AAV6 virus were manufactured by VectorBuilder Inc. (Shenandoah, Texas, USA; AAV6SP(VB190219-1010jvy)-C).

Techniques: Knock-Out, Injection, Recombinant, Virus, Control, Confocal Microscopy, Isolation, Quantitative RT-PCR, Western Blot, Climbing Assay, Knockdown, Two Tailed Test, MANN-WHITNEY