Dataset Information

Pyk2 Regulates MAMs and Mitochondrial Dynamics in Hippocampal Neurons.

ABSTRACT: Pyk2 is a non-receptor tyrosine kinase enriched in hippocampal neurons, which can be activated by calcium-dependent mechanisms. In neurons, Pyk2 is mostly localised in the cytosol and dendritic shafts but can translocate to spines and/or to the nucleus. Here, we explore the function of a new localisation of Pyk2 in mitochondria-associated membranes (MAMs), a subdomain of ER-mitochondria surface that acts as a signalling hub in calcium regulation. To test the role of Pyk2 in MAMs' calcium transport, we used full Pyk2 knockout mice (Pyk2^-/-) for in vivo and in vitro studies. Here we report that Pyk2^-/- hippocampal neurons present increased ER-mitochondrial contacts along with defective calcium homeostasis. We also show how the absence of Pyk2 modulates mitochondrial dynamics and morphology. Taken all together, our results point out that Pyk2 could be highly relevant in the modulation of ER-mitochondria calcium efflux, affecting in turn mitochondrial function.

SUBMITTER: Lopez-Molina L

PROVIDER: S-EPMC8909471 | biostudies-literature | 2022 Mar

REPOSITORIES: biostudies-literature

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Pyk2 Regulates MAMs and Mitochondrial Dynamics in Hippocampal Neurons.

López-Molina Laura L Fernández-Irigoyen Joaquín J Cifuentes-Díaz Carmen C Alberch Jordi J Girault Jean-Antoine JA Santamaría Enrique E Ginés Silvia S Giralt Albert A

Cells 20220301 5

Pyk2 is a non-receptor tyrosine kinase enriched in hippocampal neurons, which can be activated by calcium-dependent mechanisms. In neurons, Pyk2 is mostly localised in the cytosol and dendritic shafts but can translocate to spines and/or to the nucleus. Here, we explore the function of a new localisation of Pyk2 in mitochondria-associated membranes (MAMs), a subdomain of ER-mitochondria surface that acts as a signalling hub in calcium regulation. To test the role of Pyk2 in MAMs' calcium transpo ...[more]

PMID: 35269464

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Project description:BackgroundTubulin is a major substrate of the cytoplasmic class II histone deacetylase HDAC6. Inhibition of HDAC6 results in higher levels of acetylated tubulin and enhanced binding of the motor protein kinesin-1 to tubulin, which promotes transport of cargoes along microtubules. Microtubule-dependent intracellular trafficking may therefore be regulated by modulating the activity of HDAC6. We have shown previously that the neuromodulator serotonin increases mitochondrial movement in hippocampal neurons via the Akt-GSK3beta signaling pathway. Here, we demonstrate a role for HDAC6 in this signaling pathway.Methodology/principal findingsWe found that the presence of tubacin, a specific HDAC6 inhibitor, dramatically enhanced mitochondrial movement in hippocampal neurons, whereas niltubacin, an inactive tubacin analog, had no effect. Compared to control cultures, higher levels of acetylated tubulin were found in neurons treated with tubacin, and more kinesin-1 was associated with mitochondria isolated from these neurons. Inhibition of GSK3beta decreased cytoplasmic deacetylase activity and increased tubulin acetylation, whereas blockade of Akt, which phosphorylates and down-regulates GSK3beta, increased cytoplasmic deacetylase activity and decreased tubulin acetylation. Concordantly, the administration of 5-HT, 8-OH-DPAT (a specific 5-HT1A receptor agonist), or fluoxetine (a 5-HT reuptake inhibitor) increased tubulin acetylation. GSK3beta was found to co-localize with HDAC6 in hippocampal neurons, and inhibition of GSK3beta resulted in decreased binding of antibody to phosphoserine-22, a potential GSK3beta phosphorylation site in HDAC6. GSK3beta may therefore regulate HDAC6 activity by phosphorylation.Conclusions/significanceThis study demonstrates that HDAC6 plays an important role in the modulation of mitochondrial transport. The link between HDAC6 and GSK3beta, established here, has important implications for our understanding of neurodegenerative disorders. In particular, abnormal mitochondrial transport, which has been observed in such disorders as Alzheimer's disease and Parkinson's disease, could result from the misregulation of HDAC6 by GSK3beta. HDAC6 may therefore constitute an attractive target in the treatment of these disorders.

Project description:BackgroundThe trafficking of mitochondria within neurons is a highly regulated process. In an earlier study, we found that serotonin (5-HT), acting through the 5-HT1A receptor subtype, promotes axonal transport of mitochondria in cultured hippocampal neurons by increasing Akt activity, and consequently decreasing glycogen synthase kinase (GSK3beta) activity. This finding suggests a critical role for neuromodulators in the regulation of mitochondrial trafficking in neurons. In the present study, we investigate the effects of a second important neuromodulator, dopamine, on mitochondrial transport in hippocampal neurons.Methodology/principal findingsHere, we show that dopamine, like 5-HT, regulates mitochondrial motility in cultured hippocampal neurons through the Akt-GSK3beta signaling cascade. But, in contrast to the stimulatory effect of 5-HT, administration of exogenous dopamine or bromocriptine, a dopamine 2 receptor (D2R) agonist, caused an inhibition of mitochondrial movement. Moreover, pretreatment with bromocriptine blocked the stimulatory effect of 5-HT on mitochondrial movement. Conversely, in cells pretreated with 5-HT, no further increases in movement were observed after administration of haloperidol, a D2R antagonist. In contrast to the effect of the D2R agonist, addition of SKF38393, a dopamine 1 receptor (D1R) agonist, promoted mitochondrial transport, indicating that the inhibitory effect of dopamine was actually the net summation of opposing influences of the two receptor subtypes. The most pronounced effect of dopamine signals was on mitochondria that were already moving directionally. Western blot analysis revealed that treatment with either a D2R agonist or a D1R antagonist decreased Akt activity, and conversely, treatment with either a D2R antagonist or a D1R agonist increased Akt activity.Conclusions/significanceOur observations strongly suggest a role for both dopamine and 5-HT in regulating mitochondrial movement, and indicate that the integrated effects of these two neuromodulators may be important in determining the distribution of energy sources in neurons.

Dataset Information

Pyk2 Regulates MAMs and Mitochondrial Dynamics in Hippocampal Neurons.

Publications

Pyk2 Regulates MAMs and Mitochondrial Dynamics in Hippocampal Neurons.

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