The activation of hormone-sensitive lipase via MAPK phosphorylation is required for PBAN-mediated sex pheromone biosynthesis in Bombyx mori

Sex pheromones serve as crucial chemical signals used by moth species, including Bombyx mori, for reproductive communication. Although pheromone biosynthesis‑activating neuropeptide (PBAN) has been shown to regulate pheromone production via intracellular calcium signaling in B. mori, the specific Lipase responsible for triacylglycerol (TAG) lipolysis and its regulatory mechanism remain elusive. In the present study, quantitative phosphoproteomic analysis of pheromone glands (PGs) identified 5581 phosphorylation sites across 1912 proteins, revealing that PBAN triggers a series of phosphorylation cascades. Functional assays demonstrated the activation of MEK/ERK signaling cascade in response to PBAN stimulation. Further investigation confirmed the specific involvement of the MEK/ERK signaling cascade in mediating lipolysis and pheromone biosynthesis in response to PBAN stimulation, as shown by RNA interference and pharmacological inhibition studies. Moreover, hormone‑sensitive Lipase (HSL) was confirmed to be phosphorylated and activated by MEK/ERK signaling cascade in response to PBAN stimulation. A further knockdown of HSL significantly reduced pheromone titers while increasing TAG levels. In addition, CaMKII, which was activated by PBAN‑elicited CA^{2 +} influx was confirmed to stimulate the MEK/ERK signaling. Altogether, our findings elucidate a CaMKII-MAPK-HSL axis as a core regulatory mechanism linking neuroendocrine signaling (PBAN) to lipolysis and Sex Pheromone biosynthesis in B. mori. Notably, this mechanism highlights a species-specific adaptation reliant on the mobilization of lipid droplets rather than de novo synthesis of fatty acids, providing insight into the evolutionary specialization of pheromone production in lepidopteran insects.