Lack of Chloride Intracellular Channels (CLICs) confers resistance to hypoxia in Drosophila melanogaster via differential regulation of ERK and AKT pathways

Ion channels are critical regulators of cellular excitability, ionic homeostasis, and signal transduction, playing essential roles in cellular adaptation to hypoxic stress. Among these, intracellular chloride channels (CLICs) represent a unique subclass of chloride channels predominantly localized to intracellular organelles. Given their established roles in redox-regulation and transcriptional responsiveness to hypoxia, we investigated the hypoxic responses in Drosophila melanogaster , which possesses a single CLIC homolog. We subjected CLIC-null mutant flies to hypoxic stress and observed significantly enhanced resistance to hypoxia-induced damage compared to wild-type controls. Remarkably, acute hypoxic exposure followed by reoxygenation did not impair cardiac function in CLIC mutant flies, whereas wild-type flies exhibited notable cardiac dysfunction. Mutant flies also demonstrated improved overall survival under hypoxic conditions. To elucidate the underlying mechanisms of this protective phenotype, we assessed molecular markers and found a consistent downregulation of ERK expression at the transcript, total protein, and phosphorylated levels in CLIC-mutant flies. Histological analysis revealed preserved myocardial fiber architecture in mutants, in contrast to the structural disarray observed in wild-type hearts. Furthermore, we detected upregulation of pro-survival signaling, particularly the AKT pathway, evidenced by increased AKT phosphorylation. This effect was abolished upon pharmacological inhibition with rapamycin. Collectively, our findings suggest that Drosophila CLIC proteins contribute to maladaptive cardiac remodeling and suppression of cytoprotective signaling under hypoxic stress. Inhibition of CLIC function appears to confer cardioprotection and enhance organismal survival in hypoxic environments, highlighting a potential therapeutic target for ischemic heart disease.