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- Kapan, Neval, 1980-
(författare)
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A search for reciprocal signaling between insulin and adipokinetic hormone producing cells in Drosophila
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Insulin signaling in Drosophila regulates major physiological processes such as stress resistance, growth, carbohydrate and lipid metabolism, aging, reproduction and possibly diapause. Adipokinetic hormone (AKH) signaling originating from the corpora cardiaca (CC) cells, is another crucial regulator of hemolymph carbohydrate levels in Drosophila. These two systems are suggested to have opposing effects on lipid and sugar metabolism in Drosophila, reminiscent of the mammalian insulin and glucagon hormones. We studied the possible functional relationship between the insulin producing cells (IPCs) and the CC cells by interfering with insulin receptor (InR) and AKH receptor (AKH-R) expression on these cells. Our experiments revealed increased carbohydrate and lipid levels after knocking down InR in the CC cells. We also showed that diminished InR levels on the IPCs lead to increased starvation resistance, however we did not observe any changes in carbohydrate or lipid levels. So far we can only suggest action of insulins via its receptor on the IPCs and the CC cells, but we do not have conclusive data for AKH action on IPCs or CC cells.
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| 3. |
- Kapan, Neval, 1980-
(författare)
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Regulation of insulin producing cells, stress responses and metabolism in Drosophila
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In Drosophila, neuropeptides have regulatory roles in development, growth, metabolism and reproduction. This study focused on GABA and the neuropeptides Drosophila tachykinin (DTK), short neuropeptide F (sNPF), adipokinetic hormone (AKH), corazonin (CRZ) and Drosophila insulin-like peptides (DILPs) as possible regulators of metabolic stress responses and homeostasis. We showed that metabotropic GABAB receptors (GBRs) are expressed on brain insulin producing cells (IPCs), suggesting an inhibitory regulation of these cells by GABA. Knockdown of GBR on IPCs shortened lifespan and stress resistance, altered carbohydrate and lipid metabolism at stress (paper I). We showed that three different neuropeptides; DTK, sNPF and ITP, are co-expressed in five pairs of adult neurosecretory cells (paper II). ITP-knock down was not studied yet, but sNPF- and DTK-knock down flies showed decreased stress resistance at desiccation and starvation and decreased water levels at desiccation, suggesting that these peptides are involved in water homeostasis during stress conditions. sNPF was previously shown to affect feeding, growth and DILP expression via the IPCs, but it was not known which sNPF-expressing neurons are responsible for these actions. We could identify a specific set of bilateral neurons (DLPs) that co-express sNPF and corazonin that target the IPCs. We showed that these peptides co-released from DLPs regulate DILP transcription and probably release in the adult Drosophila brain and thus have roles in regulation of stress resistance and metabolism (paper III). AKH signaling was previously shown to affect hemolymph carbohydrate levels and lipid stores in Drosophila. Insulin (DILP) signaling and AKH signaling are suggested to have opposing effects on lipid and sugar metabolism in Drosophila. We studied the possible functional relationship between these two systems; do they mutually regulate each other? Our results suggest action of DILPs via the Insulin Receptor on the IPCs and the AKH producing cells, but we could not provide evidence for AKH action on IPCs or AKH cells (paper IV).
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