Fig. 5

The Hippo pathway and Dg regulate muscle size and atrophy. a Schematic drawing of a fly from lateral and cross-section views indicates the position of the analyzed IFMs. The numbers for the pairs of dorsolateral muscles (DLM) are indicated in the cross-section view. b The bar graphs represent the average sizes of the muscles in different DLM pairs in young flies (7 days old) in controls or upon downregulation of Dg (Mhc-Gal4>Dg^RNAi) and up- and downregulation of yki (Mhc-Gal4>yki^RNAi, Mhc-Gal4>yki) and kbr (Mhc-Gal4>kbr^RNAi, Mhc-Gal4>kbr). The green line outlines the averaged sizes of the young control muscles (shown in all genotypes for comparison), while the blue line indicates the aged control muscles. The yellow line corresponds to the averages of muscle size in mutant young animals, and the red line shows the average for aged animals of the corresponding genotype. Note that in all genotypes, on average, all muscles are similarly reduced in size. The correlation between the cross-sectional area of each muscle in young vs. old flies of the same genotype is shown at the top left corner of each graph (ρ = correlation index). Correlation is exclusively > 92%, signifying a nearly perfect positive correlation between 7 and 28 days (essentially, every muscle atrophies between day 7 and day 28). c The bar graph shows the average of relative muscle size in young and aged control and mutant flies. Aging causes a significant reduction in muscle size when compared to 7-day-old controls (black asterisks). Note that muscle size significantly decreases with age in all genotypes (red asterisks, compared to 7-day-old animals of the same genotype) (see also Additional file 2: Table S5). d The bar graph shows the amount of age-dependent muscle atrophy, when compared to 7-day-old animals of the same genotype (see also Additional file 2: Table S6). Note that muscle atrophy is differentially increased with age upon muscle-specific yki downregulation and kbr up- and downregulation. e The bar graph shows the absolute amount of age-dependent muscle atrophy (μm²). To measure this value, the averaged area of an individual muscle in old flies was subtracted from the corresponding value in young flies. Note that animals with kbr up- and downregulation have the highest amount of muscle size loss (see also Additional file 2: Table S6). ***p ≤ 0.001; **p ≤ 0.01; *p ≤ 0.05 (black, compared to 7-day-old control; red, compared to 7-day-old animals of the same genotype). Two-tailed Student’s t test was applied for statistical analysis