scholarly journals Mitochondria–lysosome membrane contacts are defective in GDAP1-related Charcot–Marie–Tooth disease

2020 ◽  
Author(s):  
Lara Cantarero ◽  
Elena Juárez-Escoto ◽  
Azahara Civera-Tregón ◽  
María Rodríguez-Sanz ◽  
Mónica Roldán ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Mitochondrial Membrane ◽  
Proper Function ◽  
Autophagic Flux ◽  
Mitochondrial Network ◽  
Human Neuroblastoma ◽  
Charcot Marie Tooth ◽  
Membrane Contact Sites ◽  
Membrane Contacts ◽  
Lysosome Membrane

Abstract Mutations in the GDAP1 gene cause Charcot–Marie–Tooth (CMT) neuropathy. GDAP1 is an atypical glutathione S-transferase (GST) of the outer mitochondrial membrane and the mitochondrial membrane contacts with the endoplasmic reticulum (MAMs). Here, we investigate the role of this GST in the autophagic flux and the membrane contact sites (MCSs) between mitochondria and lysosomes in the cellular pathophysiology of GDAP1 deficiency. We demonstrate that GDAP1 participates in basal autophagy and that its depletion affects LC3 and PI3P biology in autophagosome biogenesis and membrane trafficking from MAMs. GDAP1 also contributes to the maturation of lysosome by interacting with PYKfyve kinase, a pH-dependent master lysosomal regulator. GDAP1 deficiency causes giant lysosomes with hydrolytic activity, a delay in the autophagic lysosome reformation, and TFEB activation. Notably, we found that GDAP1 interacts with LAMP-1, which supports that GDAP1–LAMP-1 is a new tethering pair of mitochondria and lysosome membrane contacts. We observed mitochondria–lysosome MCSs in soma and axons of cultured mouse embryonic motor neurons and human neuroblastoma cells. GDAP1 deficiency reduces the MCSs between these organelles, causes mitochondrial network abnormalities, and decreases levels of cellular glutathione (GSH). The supply of GSH-MEE suffices to rescue the lysosome membranes and the defects of the mitochondrial network, but not the interorganelle MCSs nor early autophagic events. Overall, we show that GDAP1 enables the proper function of mitochondrial MCSs in both degradative and nondegradative pathways, which could explain primary insults in GDAP1-related CMT pathophysiology, and highlights new redox-sensitive targets in axonopathies where mitochondria and lysosomes are involved.

scholarly journals Calcium Deregulation and Mitochondrial Bioenergetics in GDAP1-Related CMT Disease

2019 ◽  
Vol 20 (2) ◽  
pp. 403 ◽  
Author(s):  
Paloma González-Sánchez ◽  
Jorgina Satrústegui ◽  
Francesc Palau ◽  
Araceli del Arco
Keyword(s):  
Mitochondrial Membrane ◽  
Energy Production ◽  
Mitochondrial Dynamics ◽  
Outer Mitochondrial Membrane ◽  
Mitochondrial Network ◽  
Charcot Marie Tooth ◽  
Calcium Deregulation ◽  
Store Operated Calcium Entry ◽  
Mitochondrial Membrane Protein ◽  
Stimulation Of

The pathology of Charcot-Marie-Tooth (CMT), a disease arising from mutations in different genes, has been associated with an impairment of mitochondrial dynamics and axonal biology of mitochondria. Mutations in ganglioside-induced differentiation-associated protein 1 (GDAP1) cause several forms of CMT neuropathy, but the pathogenic mechanisms involved remain unclear. GDAP1 is an outer mitochondrial membrane protein highly expressed in neurons. It has been proposed to play a role in different aspects of mitochondrial physiology, including mitochondrial dynamics, oxidative stress processes, and mitochondrial transport along the axons. Disruption of the mitochondrial network in a neuroblastoma model of GDAP1-related CMT has been shown to decrease Ca2+ entry through the store-operated calcium entry (SOCE), which caused a failure in stimulation of mitochondrial respiration. In this review, we summarize the different functions proposed for GDAP1 and focus on the consequences for Ca2+ homeostasis and mitochondrial energy production linked to CMT disease caused by different GDAP1 mutations.

scholarly journals Cannabidiol induces autophagy via ERK1/2 activation in neural cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Talita A. M. Vrechi ◽  
Anderson H. F. F. Leão ◽  
Ingrid B. M. Morais ◽  
Vanessa C. Abílio ◽  
Antonio W. Zuardi ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Neurodegenerative Disorders ◽  
Molecular Mechanisms ◽  
Cannabis Sativa ◽  
Autophagic Flux ◽  
Neural Cells ◽  
Human Neuroblastoma ◽  
Trpv1 Receptor ◽  
The Central Nervous System ◽  
Catabolic Process

AbstractAutophagy is a lysosomal catabolic process essential to cell homeostasis and is related to the neuroprotection of the central nervous system. Cannabidiol (CBD) is a non-psychotropic phytocannabinoid present in Cannabis sativa. Many therapeutic actions have been linked to this compound, including autophagy activation. However, the precise underlying molecular mechanisms remain unclear, and the downstream functional significance of these actions has yet to be determined. Here, we investigated CBD-evoked effects on autophagy in human neuroblastoma SH-SY5Y and murine astrocyte cell lines. We found that CBD-induced autophagy was substantially reduced in the presence of CB1, CB2 and TRPV1 receptor antagonists, AM 251, AM 630 and capsazepine, respectively. This result strongly indicates that the activation of these receptors mediates the autophagic flux. Additionally, we demonstrated that CBD activates autophagy through ERK1/2 activation and AKT suppression. Interestingly, CBD-mediated autophagy activation is dependent on the autophagy initiator ULK1, but mTORC1 independent. Thus, it is plausible that a non-canonical pathway is involved. Our findings collectively provide evidence that CBD stimulates autophagy signal transduction via crosstalk between the ERK1/2 and AKT kinases, which represent putative regulators of cell proliferation and survival. Furthermore, our study sheds light on potential therapeutic cannabinoid targets that could be developed for treating neurodegenerative disorders.

scholarly journals The PKD-Dependent Biogenesis of TGN-to-Plasma Membrane Transport Carriers

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1618
Author(s):  
Yuichi Wakana ◽  
Felix Campelo
Keyword(s):  
Cell Surface ◽  
Membrane Trafficking ◽  
Surface Protein ◽  
Membrane Contact Sites ◽  
Tissue Organization ◽  
Constitutive Secretion ◽  
Membrane Contact ◽  
Golgi Network ◽  
Organelle Membrane ◽  
And Control

Membrane trafficking is essential for processing and transport of proteins and lipids and to establish cell compartmentation and tissue organization. Cells respond to their needs and control the quantity and quality of protein secretion accordingly. In this review, we focus on a particular membrane trafficking route from the trans-Golgi network (TGN) to the cell surface: protein kinase D (PKD)-dependent pathway for constitutive secretion mediated by carriers of the TGN to the cell surface (CARTS). Recent findings highlight the importance of lipid signaling by organelle membrane contact sites (MCSs) in this pathway. Finally, we discuss our current understanding of multiple signaling pathways for membrane trafficking regulation mediated by PKD, G protein-coupled receptors (GPCRs), growth factors, metabolites, and mechanosensors.

scholarly journals Mdm1/Snx13 is a novel ER–endolysosomal interorganelle tethering protein

2015 ◽  
Vol 210 (4) ◽  
pp. 541-551 ◽  
Author(s):  
W. Mike Henne ◽  
Lu Zhu ◽  
Zsolt Balogi ◽  
Christopher Stefan ◽  
Jeffrey A. Pleiss ◽  
...  
Keyword(s):  
Neurological Disease ◽  
Lipid Binding ◽  
Sphingolipid Metabolism ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Effector Genes ◽  
Px Domain ◽  
In Trans ◽  
Membrane Contact ◽  
Lysosome Membrane

Although endolysosomal trafficking is well defined, how it is regulated and coordinates with cellular metabolism is unclear. To identify genes governing endolysosomal dynamics, we conducted a global fluorescence-based screen to reveal endomembrane effector genes. Screening implicated Phox (PX) domain–containing protein Mdm1 in endomembrane dynamics. Surprisingly, we demonstrate that Mdm1 is a novel interorganelle tethering protein that localizes to endoplasmic reticulum (ER)–vacuole/lysosome membrane contact sites (MCSs). We show that Mdm1 is ER anchored and contacts the vacuole surface in trans via its lipid-binding PX domain. Strikingly, overexpression of Mdm1 induced ER–vacuole hypertethering, underscoring its role as an interorganelle tether. We also show that Mdm1 and its paralogue Ydr179w-a (named Nvj3 in this study) localize to ER–vacuole MCSs independently of established tether Nvj1. Finally, we find that Mdm1 truncations analogous to neurological disease–associated SNX14 alleles fail to tether the ER and vacuole and perturb sphingolipid metabolism. Our work suggests that human Mdm1 homologues may play previously unappreciated roles in interorganelle communication and lipid metabolism.

scholarly journals DRAM-3 modulates autophagy and promotes cell survival in the absence of glucose

2015 ◽  
Vol 22 (10) ◽  
pp. 1714-1726 ◽  
Author(s):  
M Mrschtik ◽  
J O'Prey ◽  
L Y Lao ◽  
J S Long ◽  
F Beaumatin ◽  
...  
Keyword(s):  
Cell Survival ◽  
Membrane Trafficking ◽  
Clonogenic Survival ◽  
Autophagic Flux ◽  
Normal Tissues ◽  
Atg Proteins ◽  
Dna Damaging Agents ◽  
Evolutionarily Conserved ◽  
Starvation Conditions

Abstract Macroautophagy is a membrane-trafficking process that delivers cytoplasmic constituents to lysosomes for degradation. The process operates under basal conditions as a mechanism to turnover damaged or misfolded proteins and organelles. As a result, it has a major role in preserving cellular integrity and viability. In addition to this basal function, macroautophagy can also be modulated in response to various forms of cellular stress, and the rate and cargoes of macroautophagy can be tailored to facilitate appropriate cellular responses in particular situations. The macroautophagy machinery is regulated by a group of evolutionarily conserved autophagy-related (ATG) proteins and by several other autophagy regulators, which either have tissue-restricted expression or operate in specific contexts. We report here the characterization of a novel autophagy regulator that we have termed DRAM-3 due to its significant homology to damage-regulated autophagy modulator (DRAM-1). DRAM-3 is expressed in a broad spectrum of normal tissues and tumor cells, but different from DRAM-1, DRAM-3 is not induced by p53 or DNA-damaging agents. Immunofluorescence studies revealed that DRAM-3 localizes to lysosomes/autolysosomes, endosomes and the plasma membrane, but not the endoplasmic reticulum, phagophores, autophagosomes or Golgi, indicating significant overlap with DRAM-1 localization and with organelles associated with macroautophagy. In this regard, we further proceed to show that DRAM-3 expression causes accumulation of autophagosomes under basal conditions and enhances autophagic flux. Reciprocally, CRISPR/Cas9-mediated disruption of DRAM-3 impairs autophagic flux confirming that DRAM-3 is a modulator of macroautophagy. As macroautophagy can be cytoprotective under starvation conditions, we also tested whether DRAM-3 could promote survival on nutrient deprivation. This revealed that DRAM-3 can repress cell death and promote long-term clonogenic survival of cells grown in the absence of glucose. Interestingly, however, this effect is macroautophagy-independent. In summary, these findings constitute the primary characterization of DRAM-3 as a modulator of both macroautophagy and cell survival under starvation conditions.

scholarly journals Mammalian PITPs at the Golgi and ER-Golgi Membrane Contact Sites

Contact ◽  
2020 ◽  
Vol 3 ◽  
pp. 251525642096417
Author(s):  
Shamshad Cockcroft ◽  
Sima Lev
Keyword(s):  
Membrane Trafficking ◽  
Golgi Membrane ◽  
Intracellular Membrane ◽  
Functional Studies ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Biochemical Genetic ◽  
Membrane Contact ◽  
Intracellular Membrane Transport ◽  
Exchange Activity

Phosphatidylinositol (PI)-transfer proteins (PITPs) have been long recognized as proteins that modulate phosphoinositide levels in membranes through their intrinsic PI/PC-exchange activity. Recent studies from flies and mammals suggest that certain PITPs bind phosphatidic acid (PA) and possess PI/PA-exchange activity. Phosphoinositides and PA play critical roles in cell signaling and membrane trafficking, and numerous biochemical, genetic and functional studies have shown that PITPs regulate cellular lipid metabolism, various signaling pathways and intracellular membrane transport events. In this mini-review, we discuss the function of mammalian PITPs at the Golgi and ER-Golgi membrane contact sites (MCS) and highlight DAG (Diacylglycerol) as a central hub of PITPs functions. We describe PITPs-associated phospho-signaling network at the ER-Golgi interface, and share our perspective on future studies related to PITPs at MCSs.

scholarly journals Genotype-Phenotype Correlations in Charcot-Marie-Tooth Disease Due to MTMR2 Mutations and Implications in Membrane Trafficking

2019 ◽  
Vol 13 ◽  
Author(s):  
Haicui Wang ◽  
Ayşe Kaçar Bayram ◽  
Rosanne Sprute ◽  
Ozkan Ozdemir ◽  
Emily Cooper ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Charcot Marie Tooth ◽  
Charcot Marie Tooth Disease ◽  
Tooth Disease

scholarly journals Kv2 potassium channels form endoplasmic reticulum/plasma membrane junctions via interaction with VAPA and VAPB

2018 ◽  
Vol 115 (31) ◽  
pp. E7331-E7340 ◽  
Author(s):  
Ben Johnson ◽  
Ashley N. Leek ◽  
Laura Solé ◽  
Emily E. Maverick ◽  
Tim P. Levine ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Neuronal Cultures ◽  
Physical Relationship ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Hek Cells ◽  
C Terminus ◽  
Membrane Contact

Kv2.1 exhibits two distinct forms of localization patterns on the neuronal plasma membrane: One population is freely diffusive and regulates electrical activity via voltage-dependent K+ conductance while a second one localizes to micrometer-sized clusters that contain densely packed, but nonconducting, channels. We have previously established that these clusters represent endoplasmic reticulum/plasma membrane (ER/PM) junctions that function as membrane trafficking hubs and that Kv2.1 plays a structural role in forming these membrane contact sites in both primary neuronal cultures and transfected HEK cells. Clustering and the formation of ER/PM contacts are regulated by phosphorylation within the channel C terminus, offering cells fast, dynamic control over the physical relationship between the cortical ER and PM. The present study addresses the mechanisms by which Kv2.1 and the related Kv2.2 channel interact with the ER membrane. Using proximity-based biotinylation techniques in transfected HEK cells we identified ER VAMP-associated proteins (VAPs) as potential Kv2.1 interactors. Confirmation that Kv2.1 and -2.2 bind VAPA and VAPB employed colocalization/redistribution, siRNA knockdown, and Förster resonance energy transfer (FRET)-based assays. CD4 chimeras containing sequence from the Kv2.1 C terminus were used to identify a noncanonical VAP-binding motif. VAPs were first identified as proteins required for neurotransmitter release in Aplysia and are now known to be abundant scaffolding proteins involved in membrane contact site formation throughout the ER. The VAP interactome includes AKAPs, kinases, membrane trafficking machinery, and proteins regulating nonvesicular lipid transport from the ER to the PM. Therefore, the Kv2-induced VAP concentration at ER/PM contact sites is predicted to have wide-ranging effects on neuronal cell biology.

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