Control of Metabolic Homeostasis by Stress Signaling Is Mediated by the Lipocalin NLaz
Figure 6
NLaz antagonizes IIS in larvae.
(A–C) tGPH fluorescence [50] in larval fatbodies. (A) NLazCNW14/CNW14. (B) NLazNW5/NW5. Membrane localization of tGPH is increased in NLaz mutants compared to isogenic wild-type controls, indicating elevated PI3K activity. (C) Ratios of average membrane vs. nuclear fluorescence as determined using NIH ImageJ on images of fatbody cells of independent individuals. n = 6 for NLazCNW14/CNW14, n = 10 for NLazNW5/NW5. P value from Student's T test. (D) NLaz mutant third-instar larvae (homozygotes for NLazNW5/NW5) exhibit strongly decreased Glycogen stores compared to isogenic wild-type controls (NLazCNW14/CNW14). Glucose and Triglyceride levels do not differ in wild-type or NLaz mutant larvae. (E) Established Foxo target genes are induced in response to NLaz overexpression in the larval fatbody. Real-time PCR was performed to quantify dInR, dLip4, and hsp22 transcript levels in extracts of whole third-instar larvae. Transcript levels were normalized to actin5C and ratios of transcript levels in NLaz expressing larvae (pplG4/pplG4,tubGal80ts; UASNLaz/+) and in wildtype controls (pplG4/pplG4, tubGal80ts; +/+) are shown for control conditions (18°C) and after heat-shock. p-values from Student's Ttest. (F) Over-expression of NLaz in the fatbody results in elevated hemolymph glucose levels. Experiments were performed in larvae of the following genotypes: pplG4/+;+/+; pplG4/+; UASNlaz/+. (G) Comparison of adult sibling males of the following genotypes, reared at 29°C: pplG4; +/+. pplG4,NLazNW5/NW5;+/+; pplG4,NLazNW5/NW5;UASNlaz/+. Overall weight is increased in NLaz mutants. Size is decreased again in animals over-expressing NLaz in the fatbody. Fresh weight of males of the indicated genotypes.