bims-mecmid 2021-11-07 papers

Cell Death Dis. 2021 Nov 05. 12(11): 1050

Mitochondrial Drp1 recognizes and induces excessive mPTP opening after hypoxia through BAX-PiC and LRRK2-HK2.

Chenyang Duan, Lei Kuang, Chen Hong, Xinming Xiang, Jiancang Liu, Qinghui Li, Xiaoyong Peng, Yuanqun Zhou, Hongchen Wang, Liangming Liu, Tao Li.

Mitochondrial mass imbalance is one of the key causes of cardiovascular dysfunction after hypoxia. The activation of dynamin-related protein 1 (Drp1), as well as its mitochondrial translocation, play important roles in the changes of both mitochondrial morphology and mitochondrial functions after hypoxia. However, in addition to mediating mitochondrial fission, whether Drp1 has other regulatory roles in mitochondrial homeostasis after mitochondrial translocation is unknown. In this study, we performed a series of interaction and colocalization assays and found that, after mitochondrial translocation, Drp1 may promote the excessive opening of the mitochondrial permeability transition pore (mPTP) after hypoxia. Firstly, mitochondrial Drp1 maximumly recognizes mPTP channels by binding Bcl-2-associated X protein (BAX) and a phosphate carrier protein (PiC) in the mPTP. Then, leucine-rich repeat serine/threonine-protein kinase 2 (LRRK2) is recruited, whose kinase activity is inhibited by direct binding with mitochondrial Drp1 after hypoxia. Subsequently, the mPTP-related protein hexokinase 2 (HK2) is inactivated at Thr-473 and dissociates from the mitochondrial membrane, ultimately causing structural disruption and overopening of mPTP, which aggravates mitochondrial and cellular dysfunction after hypoxia. Thus, our study interprets the dual direct regulation of mitochondrial Drp1 on mitochondrial morphology and functions after hypoxia and proposes a new mitochondrial fission-independent mechanism for the role of Drp1 after its translocation in hypoxic injury.

DOI: https://doi.org/10.1038/s41419-021-04343-x

FEBS J. 2021 Nov 05.

FAK regulates cardiomyocyte mitochondrial fission and function through Drp1.

Yu-Wang Chang, Zong-Han Song, Chien-Chang Chen.

Loss of the mitochondrial fission enzyme dynamin-related protein 1 (Drp1) in cardiomyocytes results in energy shortage and heart failure. We aim to understand the intracellular signal pathway and extracellular factors regulating Drp1 phosphorylation and mitochondrial morphology and function in cardiomyocytes. We found cyclic mechanical stretching induced mitochondrial fission through Drp1 and focal adhesion kinase (FAK) in neonatal rat ventricular myocytes (NRVMs). FAK regulated phosphorylation of Drp1 and mitochondrial Drp1 levels. Extracellular fibronectin activated Drp1 and caused mitochondrial fission through FAK and extracellular signal-regulated kinase 1/2 (ERK1/2). Fibronectin increased NRVMs oxygen consumption rate and ATP content via FAK-ERK1/2-Drp1. Inhibition of the FAK-ERK1/2-Drp1 pathway caused cellular energy shortage. In addition, the FAK-ERK1/2-Drp1 pathway was rapidly activated by adrenergic agonists and contributed to agonists-stimulated NRVMs respiration. Interestingly, fibronectin limited the adrenergic agonists-induced NRVMs respiration by restricting phosphorylation of Drp1. Our results suggest that extracellular fibronectin and adrenergic stimulations use the FAK-ERK1/2-Drp1 pathway to regulate mitochondrial morphology and function in cardiomyocytes.

Keywords: Drp1; FAK; fibronectin; mitochondrial fission

DOI: https://doi.org/10.1111/febs.16263

Shock. 2021 Nov 03.

δPKC-Mediated Drp1 Phosphorylation Impacts Macrophage Mitochondrial Function and Inflammatory Response to Endotoxin.

Amanda J Lin, Amit U Joshi, Riddhita Mukherjee, Carly A Tompkins, Vijith Vijayan, Daria Mochly-Rosen, Bereketeab Haileselassie.

BACKGROUND: Recent studies have demonstrated that alterations in mitochondrial dynamics can impact innate immune function. However, the upstream mechanisms which link mitochondrial dynamics to innate immune phenotypes have not been completely elucidated. This study asks if δPKC-mediated phosphorylation of Drp1, a key driver of mitochondrial fission, impacts macrophage pro-inflammatory response following bacterial-derived lipopolysaccharide (LPS) stimulation.
METHODS: Using RAW 264.7 cells, bone marrow-derived macrophages from C57BL/6J mice, as well as human monocyte-derived macrophages, we first characterized changes in δPKC-mediated phosphorylation of Drp1 following LPS stimulation. Next, using rationally-designed peptides that inhibit δPKC activation (δV1-1) and δPKC-Drp1 interaction (ψDrp1), we determined whether δPKC-mediated phosphorylation of Drp1 impacts LPS-induced changes in mitochondrial morphology, mitochondrial function, and inflammatory response.
RESULTS: Our results demonstrated that δPKC-dependent Drp1 activation is associated with increased mitochondrial fission, impaired cellular respiration, and increased mitochondrial reactive oxygen species in LPS-treated macrophages. This is reversed using a rationally-designed peptide which selectively inhibits δPKC phosphorylation of Drp1 (ψDrp1). Interestingly, limiting excessive mitochondrial fission using ψDrp1 reduced LPS-triggered pro-inflammatory response, including a decrease in NF-κB nuclear localization, decreased iNOS induction, and a reduction in pro-inflammatory cytokines (IL-1β, TNFα, IL-6).
CONCLUSION: These data suggest that inhibiting Drp1 phosphorylation by δPKC abates the excessive mitochondrial fragmentation and mitochondrial dysfunction that is seen following LPS treatment. Furthermore, these data suggest that limiting δPKC-dependent Drp1 activation decreases the pro-inflammatory response following LPS treatment. Altogether, δPKC-dependent Drp1 phosphorylation might be an upstream mechanistic link between alterations in mitochondrial dynamics and innate immune phenotypes, and may have therapeutic potential.

DOI: https://doi.org/10.1097/SHK.0000000000001885

Front Cell Dev Biol. 2021 ;9 752260

SENP3 Promotes an Mff-Primed Bcl-x L -Drp1 Interaction Involved in Cell Death Following Ischemia.

Chun Guo, Keri L Hildick, Juwei Jiang, Alice Zhao, Wenbin Guo, Jeremy M Henley, Kevin A Wilkinson.

Dysregulation of the mitochondrial fission machinery has been linked to cell death following ischemia. Fission is largely dependent on recruitment of Dynamin-related protein 1 (Drp1) to the receptor Mitochondrial fission factor (Mff) located on the mitochondrial outer membrane (MOM). Drp1 is a target for SUMOylation and its deSUMOylation, mediated by the SUMO protease SENP3, enhances the Drp1-Mff interaction to promote cell death in an oxygen/glucose deprivation (OGD) model of ischemia. Another interacting partner for Drp1 is the Bcl-2 family member Bcl-x L , an important protein in cell death and survival pathways. Here we demonstrate that preventing Drp1 SUMOylation by mutating its SUMO target lysines enhances the Drp1-Bcl-x L interaction in vivo and in vitro. Moreover, SENP3-mediated deSUMOylation of Drp1 promotes the Drp1-Bcl-x L interaction. Our data suggest that Mff primes Drp1 binding to Bcl-x L at the mitochondria and that Mff and Bcl-x L can interact directly, independent of Drp1, through their transmembrane domains. Importantly, SENP3 loss in cells subjected to OGD correlates with reduced Drp1-Bcl-x L interaction, whilst recovery of SENP3 levels in cells subjected to reoxygenation following OGD correlates with increased Drp1-Bcl-x L interaction. Expressing a Bcl-x L mutant with defective Drp1 binding reduces OGD plus reoxygenation-evoked cell death. Taken together, our results indicate that SENP3-mediated deSUMOlyation promotes an Mff-primed Drp1-Bcl-x L interaction that contributes to cell death following ischemia.

Keywords: Bcl-xL; Drp1; Mff; SENP3; SUMOylation; ischemia

DOI: https://doi.org/10.3389/fcell.2021.752260

Nanoscale. 2021 Nov 05.

Super-resolution FRET measurements.

Alan M Szalai, Cecilia Zaza, Fernando D Stefani.

Super-resolution fluorescence microscopy and Förster Resonance Energy Transfer (FRET) form a well-established family of techniques that has provided unique tools to study the dynamic architecture and functionality of biological systems, as well as to investigate nanomaterials. In the last years, the integration of super-resolution methods with FRET measurements has generated advances in two fronts. On the one hand, FRET-based probes have enhanced super-resolution imaging. On the other, the development of super-resolved FRET imaging methods has allowed the visualization of molecular interaction patterns with higher spatial resolution, less averaging and higher dynamic range. Here, we review these advances and discuss future perspectives, including the possible integration of FRET with next generation super-resolution techniques capable of reaching true molecular-scale spatial resolution.

DOI: https://doi.org/10.1039/d1nr05769c

Environ Toxicol. 2021 Nov 05.

Resveratrol reduces DRP1-mediated mitochondrial dysfunction via the SIRT1-PGC1α signaling pathway in manganese-induced nerve damage in mice.

Meng-Yu Lei, Lin Cong, Zhi-Qi Liu, Zhuo-Fan Liu, Zhuo Ma, Kuan Liu, Jing Li, Yu Deng, Wei Liu, Bin Xu.

Excessive manganese (Mn) exposure can cause nerve damage and mitochondrial dysfunction, which may involve defects in mitochondrial dynamics. Resveratrol (RSV) exerts a wide range of beneficial effects via activation of sirtuin 1 (SIRT1) and thus may positively impact Mn-induced mitochondrial damage through the regulation of peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1α) by SIRT1. In this study, we investigated the molecular mechanisms by which RSV alleviates the nerve injury and mitochondrial fragmentation caused by Mn in C57 BL/6 mice. Our results demonstrated that RSV activated the deacetylase activity of SIRT1 and protected against the surge of mitochondrial reactive oxygen species, the loss of mitochondrial membrane potential, and the attenuation of ATP caused by Mn. RSV, therefore, inhibits mitochondrial fragmentation and safeguards neural cells. Increased deacetylase activity led to a reduction in the acetylation of PGC-1α, which directly regulates DRP1 expression by binding to the DRP1 promoter. The resultant attenuation of DRP1-mediated mitochondrial fragmentation in RSV-pretreated mice was abolished by the addition of the SIRT1 inhibitor EX527. Taken together, these findings indicate that RSV alleviates Mn-induced mitochondrial dysfunction mediated by DRP1 by modulating the SIRT1/PGC-1α signaling pathway.

Keywords: dynamin-related protein 1; mitochondrial fragmentization; neurotoxicity; sirtuin1

DOI: https://doi.org/10.1002/tox.23397