Germline expression of Imp-L2 in Drosophila females enhances reproductive activity and longevity

The Imaginal morphogenesis protein-Late 2 (Imp-L2) in Drosophila is recognized as a functional homolog of the insulin-like growth factor (IGF) binding protein family. In this study, we report that Imp-L2 expression in germline cells during oogenesis simultaneously enhances both fecundity and lifespan in female Drosophila. Loss of Imp-L2, either through knockout or germline-specific knockdown, resulted in decreased reproductive activity, as evidenced by reduced ovary size and fecundity, along with a higher proportion of infertile flies. Conversely, overexpression of Imp-L2 specifically in germline cells enhanced reproductive activity. Imp-L2 appears to regulate germline stem cell proliferation and differentiation independently of IGF signaling. Interestingly, germline-specific knockdown of Imp-L2 shortened the lifespan of female flies, whereas its overexpression extended it. Thus, Imp-L2 expression in the germline promotes both reproductive activity and longevity, presenting an exception to the typical trade-off between reproduction and lifespan.