The corticotropin-releasing factor-like diuretic hormone 44 (DH(44)) and kinin neuropeptides modulate desiccation and starvation tolerance in Drosophila melanogaster

Malpighian tubules are critical organs for epithelial fluid transport and stress tolerance in insects, and are under neuroendocrine control by multiple neuropeptides secreted by identified neurons. Here, we demonstrate roles for CRF-like diuretic hormone 44 (DH(44)) and Drosophila melanogaster kinin (Drome-kinin, DK) in desiccation and starvation tolerance. Gene expression and labelled DH(44) ligand binding data, as well as highly selective knockdowns and/or neuronal ablations of DH(44) in neurons of the pars intercerebralis and DH(44) receptor (DH(44)-R2) in Malpighian tubule principal cells, indicate that suppression of DH(44) signalling improves desiccation tolerance of the intact fly. Drome-kinin receptor, encoded by the leucokinin receptor gene, LKR, is expressed in DH(44) neurons as well as in stellate cells of the Malpighian tubules. LKR knockdown in DH(44)-expressing neurons reduces Malpighian tubule-specific LKR, suggesting interactions between DH(44) and LK signalling pathways. Finally, although a role for DK in desiccation tolerance was not defined, we demonstrate a novel role for Malpighian tubule cell-specific LKR in starvation tolerance. Starvation increases gene expression of epithelial LKR. Also, Malpighian tubule stellate cell-specific knockdown of LKR significantly reduced starvation tolerance, demonstrating a role for neuropeptide signalling during starvation stress.