AMPK-dependent activation of the Cyclin Y/CDK16 complex controls autophagy.
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ABSTRACT:
SUBMITTER: Dohmen M
PROVIDER: S-EPMC7042329 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The AMP-activated protein kinase (AMPK) is a master sensor of the cellular energy status and is crucial for the adaptive response to limited energy availability. AMPK is implicated in the regulation of many cellular processes, including autophagy. However, the precise mechanisms by which AMPK controls these processes and the identities of relevant substrates are not fully understood. With a protein microarrays we identified Cyclin Y as novel AMPK substrate that is phosphorylated at S326 both in vitro and in cells. Phosphorylation of Cyclin Y at S326 promotes its interaction with the cyclin-dependent kinase 16 (CDK16), thereby stimulating its catalytic activity. When expressed in cells, Cyclin Y/CDK16 is sufficient to promote autophagy. Moreover, Cyclin Y/CDK16 is necessary for efficient AMPK-dependent activation of autophagy. This functional interaction is mediated by AMPK phosphorylating S326 of Cyclin Y. Collectively, we define Cyclin Y/CDK16 as downstream effector of AMPK for inducing autophagy.
2020-02-17 | PXD009968 | Pride
Project description:Tuberous sclerosis complex (TSC) is a disorder arising from mutation in the TSC1 or TSC2 gene, characterized by the development of hamartomas in various organs and neurological manifestations including epilepsy, intellectual disability and autism. TSC1/2 protein complex negatively regulates the mammalian target of rapamycin complex 1 (mTORC1) a master regulator of protein synthesis, cell growth and autophagy. Autophagy is a cellular quality-control process that sequesters cytosolic material in double membrane vesicles called autophagosomes and degrades it in autolysosomes. Previous studies in dividing cells have shown that mTORC1 blocks autophagy through inhibition of Unc-51-like-kinase1/2 (ULK1/2). Despite the fact that autophagy plays critical roles in neuronal homeostasis, little is known on the regulation of autophagy in neurons. Here we show that unlike in non-neuronal cells, Tsc2-deficient neurons have increased autolysosome accumulation and autophagic flux despite mTORC1-dependent inhibition of ULK1. Our data demonstrate that loss of Tsc2 results in autophagic activity via AMPK-dependent activation of ULK1. Thus, in Tsc2-knockdown neurons AMPK activation is the dominant regulator of autophagy. Notably, increased AMPK activity and autophagy activation are also found in the brains of Tsc1-conditional mouse models and in cortical tubers resected from TSC patients. Together, our findings indicate that neuronal Tsc1/2 complex activity is required for the coordinated regulation of autophagy by AMPK. By uncovering the autophagy dysfunction associated with Tsc2 loss in neurons, our work sheds light on a previously uncharacterized cellular mechanism that contributes to altered neuronal homeostasis in TSC disease.
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Project description:Cell cycle transitions are generally triggered by variation in the activity of cyclin-dependent kinases (CDKs) bound to cyclins. Malaria-causing parasites have a life cycle with unique cell-division cycles, and a repertoire of divergent CDKs and cyclins of poorly understood function and interdependency. We show that Plasmodium berghei CDK-related kinase 5 (CRK5), is a critical regulator of atypical mitosis in the gametogony and is required for mosquito transmission. It phosphorylates canonical CDK motifs of components in the pre-replicative complex and is essential for DNA replication. During a replicative cycle, CRK5 stably interacts with a single Plasmodium-specific cyclin (SOC2), although we obtained no evidence of SOC2 cycling by transcription, translation or degradation. Our results provide evidence that during Plasmodium male gametogony, this divergent cyclin/CDK pair fills the functional space of other eukaryotic cell-cycle kinases controlling DNA replication.
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Project description:Hepatocellular carcinoma (HCC) is the third cause of cancer-related death worldwide. When these tumors are in advanced stages, few therapeutic options are available. Therefore, it is essential to search for new treatments to fight this disease. In this study, we investigated the effects of cannabinoids--a novel family of potential anticancer agents--on the growth of HCC. We found that Δ(9)-tetrahydrocannabinol (Δ(9)-THC, the main active component of Cannabis sativa) and JWH-015 (a cannabinoid receptor 2 (CB(2)) cannabinoid receptor-selective agonist) reduced the viability of the human HCC cell lines HepG2 (human hepatocellular liver carcinoma cell line) and HuH-7 (hepatocellular carcinoma cells), an effect that relied on the stimulation of CB(2) receptor. We also found that Δ(9)-THC- and JWH-015-induced autophagy relies on tribbles homolog 3 (TRB3) upregulation, and subsequent inhibition of the serine-threonine kinase Akt/mammalian target of rapamycin C1 axis and adenosine monophosphate-activated kinase (AMPK) stimulation. Pharmacological and genetic inhibition of AMPK upstream kinases supported that calmodulin-activated kinase kinase β was responsible for cannabinoid-induced AMPK activation and autophagy. In vivo studies revealed that Δ(9)-THC and JWH-015 reduced the growth of HCC subcutaneous xenografts, an effect that was not evident when autophagy was genetically of pharmacologically inhibited in those tumors. Moreover, cannabinoids were also able to inhibit tumor growth and ascites in an orthotopic model of HCC xenograft. Our findings may contribute to the design of new therapeutic strategies for the management of HCC.
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Project description:Background and purposeRecent clinical trials report that metformin, an activator of AMP-activated protein kinase (AMPK) used to treat type 2 diabetes, significantly reduces the risk of stroke by actions that are independent of its glucose-lowering effects. However, the underlying molecular mechanisms are not known. Here, we tested the possibility that acute metformin preconditioning confers neuroprotection by pre-activation of AMPK-dependent autophagy in a rat model of permanent middle cerebral artery occlusion (pMCAO).Experimental approachMale Sprague-Dawley rats were pretreated with either vehicle, an AMPK inhibitor, Compound C, or an autophagy inhibitor, 3-methyladenine, and were injected with a single dose of metformin (10 mg kg(-1), i.p.). Then, AMPK activity and autophagy biomarkers in the brain were assessed. At 24 h after metformin treatment, rats were subjected to pMCAO; infarct volume, neurological deficits and cell apoptosis were evaluated 24 and 96 h later.Key resultsA single dose of metformin significantly activated AMPK and induced autophagy in the brain. The enhanced autophagic activity was inhibited by Compound C pretreatment. Furthermore, acute metformin preconditioning significantly reduced infarct volume, neurological deficits and cell apoptosis during a subsequent focal cerebral ischaemia. The neuroprotection mediated by metformin preconditioning was fully abolished by Compound C and partially inhibited by 3-methyladenine.Conclusions and implicationsThese results provide the first evidence that acute metformin preconditioning induces autophagy by activation of brain AMPK, which confers neuroprotection against subsequent cerebral ischaemia. This suggests that metformin, a well-known hypoglycaemic drug, may have a practical clinical use for stroke prevention.
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