Insulin and insulin growth factor have central roles in growth, metabolism and ageing of animals, including Drosophila melanogaster. In Drosophila, insulin-like peptides (Dilps) are produced by specialized neurons in the brain. Here we show that Drosophila short neuropeptide F (sNPF), an orthologue of mammalian neuropeptide Y (NPY), and sNPF receptor sNPFR1 regulate expression of Dilps. Body size was increased by overexpression of sNPF or sNPFR1. The fat body of sNPF mutant Drosophila had downregulated Akt, nuclear localized FOXO, upregulated translational inhibitor 4E-BP and reduced cell size. Circulating levels of glucose were elevated and lifespan was also extended in sNPF mutants. We show that these effects are mediated through activation of extracellular signal-related kinases (ERK) in insulin-producing cells of larvae and adults. Insulin expression was also increased in an ERK-dependent manner in cultured Drosophila central nervous system (CNS) cells and in rat pancreatic cells treated with sNPF or NPY peptide, respectively. Drosophila sNPF and the evolutionarily conserved mammalian NPY seem to regulate ERK-mediated insulin expression and thus to systemically modulate growth, metabolism and lifespan.

Calcium (Ca) homeostasis is essential for neuronal function and survival. Altered Ca homeostasis has been consistently observed in neurological diseases. How Ca homeostasis is achieved in various cellular compartments of disease-relevant cell types is not well understood. Here we show in Parkinson's disease (PD) models that Ca transport from the endoplasmic reticulum (ER) to mitochondria through the ER-mitochondria contact site (ERMCS) critically regulates mitochondrial Ca (mito-Ca) homeostasis in dopaminergic (DA) neurons, and that the PD-associated PINK1 protein modulates this process. In mutant DA neurons, the ERMCS is strengthened and mito-Ca level is elevated, resulting in mitochondrial enlargement and neuronal death. Miro, a well-characterized component of the mitochondrial trafficking machinery, mediates the effects of PINK1 on mito-Ca and mitochondrial morphology, apparently in a transport-independent manner. Miro overexpression mimics loss-of-function effect, whereas inhibition of Miro or components of the ERMCS, or pharmacological modulation of ERMCS function, rescued mutant phenotypes. Mito-Ca homeostasis is also altered in the LRRK2-G2019S model of PD and the PAR-1/MARK model of neurodegeneration, and genetic or pharmacological restoration of mito-Ca level is beneficial in these models. Our results highlight the importance of mito-Ca homeostasis maintained by Miro and the ERMCS to mitochondrial physiology and neuronal integrity. Targeting this mito-Ca homeostasis pathway holds promise for a therapeutic strategy for neurodegenerative diseases.

Feeding behavior is one of the most essential activities in animals, which is tightly regulated by neuroendocrine factors. Drosophila melanogaster short neuropeptide F (sNPF) and the mammalian functional homolog neuropeptide Y (NPY) regulate food intake. Understanding the molecular mechanism of sNPF and NPY signaling is critical to elucidate feeding regulation. Here, we found that minibrain (mnb) and the mammalian ortholog Dyrk1a target genes of sNPF and NPY signaling and regulate food intake in Drosophila melanogaster and mice. In Drosophila melanogaster neuronal cells and mouse hypothalamic cells, sNPF and NPY modulated the mnb and Dyrk1a expression through the PKA-CREB pathway. Increased Dyrk1a activated Sirt1 to regulate the deacetylation of FOXO, which potentiated FOXO-induced sNPF/NPY expression and in turn promoted food intake. Conversely, AKT-mediated insulin signaling suppressed FOXO-mediated sNPF/NPY expression, which resulted in decreasing food intake. Furthermore, human Dyrk1a transgenic mice exhibited decreased FOXO acetylation and increased NPY expression in the hypothalamus, as well as increased food intake. Our findings demonstrate that Mnb/Dyrk1a regulates food intake through the evolutionary conserved Sir2-FOXO-sNPF/NPY pathway in Drosophila melanogaster and mammals.

DYRK1A is important in neuronal development and function, and its excessive activity is considered a significant pathogenic factor in Down syndrome and Alzheimer's disease. Thus, inhibition of DYRK1A has been suggested to be a new strategy to modify the disease. Very few compounds, however, have been reported to act as inhibitors, and their potential clinical uses require further evaluation. Here, we newly identify CX-4945, the safety of which has been already proven in the clinical setting, as a potent inhibitor of DYRK1A that acts in an ATP-competitive manner. The inhibitory potency of CX-4945 on DYRK1A (IC50=6.8 nM) in vitro was higher than that of harmine, INDY or proINDY, which are well-known potent inhibitors of DYRK1A. CX-4945 effectively reverses the aberrant phosphorylation of Tau, amyloid precursor protein (APP) and presenilin 1 (PS1) in mammalian cells. To our surprise, feeding with CX-4945 significantly restored the neurological and phenotypic defects induced by the overexpression of minibrain, an ortholog of human DYRK1A, in the Drosophila model. Moreover, oral administration of CX-4945 acutely suppressed Tau hyperphosphorylation in the hippocampus of DYRK1A-overexpressing mice. Our research results demonstrate that CX-4945 is a potent DYRK1A inhibitor and also suggest that it has therapeutic potential for DYRK1A-associated diseases.

The abnormal assembly of β-amyloid (Aβ) peptides into neurotoxic, β-sheet-rich amyloid aggregates is a major pathological hallmark of Alzheimer's disease (AD). Light-induced photosensitizing molecules can regulate Aβ amyloidogenesis. Multiple photochemical analyses using circular dichroism, atomic force microscopy, dot blot, and native gel electrophoresis verified that photoactivated meso-tetra(4-sulfonatophenyl)porphyrin (TPPS with M = 2H(+), Zn(2+), Cu(2+), Mn(2+)) successfully inhibits Aβ aggregation in vitro. Furthermore, Aβ toxicity was relieved in the photoexcited-TPPS-treated Drosophila AD model. TPPS suppresses neural cell death, synaptic toxicity, and behavioral defects in the Drosophila AD model under blue light illumination. Behavioral phenotypes, including larval locomotion defect and short lifespan caused by Aβ overexpression, were also rescued by blue light-excited TPPS.