Regulatory Roles of Drosophila Insulin-Like Peptide 1 (DILP1) in Metabolism Differ in Pupal and Adult Stages.
Front. Endocrinol.. 2020-04-21; 11:
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Liao S(1), Post S(2), Lehmann P(1), Veenstra JA(3), Tatar M(2), Nässel DR(1).
(1)Department of Zoology, Stockholm University, Stockholm, Sweden.
(2)Department of Ecology and Evolutionary Biology, Brown University, Providence,
RI, United States.
(3)Institut de Neurosciences Cognitives et Intégratives d’Aquitaine (CNRS
UMR5287), University of Bordeaux, Pessac, France.
The insulin/IGF-signaling pathway is central in control of nutrient-dependent
growth during development, and in adult physiology and longevity. Eight
insulin-like peptides (DILP1-8) have been identified in Drosophila, and several
of these are known to regulate growth, metabolism, reproduction, stress
responses, and lifespan. However, the functional role of DILP1 is far from
understood. Previous work has shown that dilp1/DILP1 is transiently expressed
mainly during the pupal stage and the first days of adult life. Here, we study
the role of dilp1 in the pupa, as well as in the first week of adult life, and
make some comparisons to dilp6 that displays a similar pupal expression profile,
but is expressed in fat body rather than brain neurosecretory cells. We show that
mutation of dilp1 diminishes organismal weight during pupal development, whereas
overexpression increases it, similar to dilp6 manipulations. No growth effects of
dilp1 or dilp6 manipulations were detected during larval development. We next
show that dilp1 and dilp6 increase metabolic rate in the late pupa and promote
lipids as the primary source of catabolic energy. Effects of dilp1 manipulations
can also be seen in the adult fly. In newly eclosed female flies, survival during
starvation is strongly diminished in dilp1 mutants, but not in dilp2 and
dilp1/dilp2 mutants, whereas in older flies, only the double mutants display
reduced starvation resistance. Starvation resistance is not affected in male
dilp1 mutant flies, suggesting a sex dimorphism in dilp1 function. Overexpression
of dilp1 also decreases survival during starvation in female flies and increases
egg laying and decreases egg to pupal viability. In conclusion, dilp1 and dilp6
overexpression promotes metabolism and growth of adult tissues during the pupal
stage, likely by utilization of stored lipids. Some of the effects of the dilp1
manipulations may carry over from the pupa to affect physiology in young adults,
but our data also suggest that dilp1 signaling is important in metabolism and
stress resistance in the adult stage.
Copyright © 2020 Liao, Post, Lehmann, Veenstra, Tatar and Nässel.