FHL2 anchors mitochondria to actin and adapts mitochondrial dynamics to glucose supply

2021 ◽  
Vol 220 (10) ◽  
Author(s):  
Himanish Basu ◽  
Gulcin Pekkurnaz ◽  
Jill Falk ◽  
Wei Wei ◽  
Morven Chin ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Mitochondrial Dynamics ◽  
Neuronal Cells ◽  
Mitochondrial Movement ◽  
Lim Domains ◽  
Necessary And Sufficient ◽  
Glucose Supply ◽  
Glucose Availability

Mitochondrial movement and distribution are fundamental to their function. Here we report a mechanism that regulates mitochondrial movement by anchoring mitochondria to the F-actin cytoskeleton. This mechanism is activated by an increase in glucose influx and the consequent O-GlcNAcylation of TRAK (Milton), a component of the mitochondrial motor-adaptor complex. The protein four and a half LIM domains protein 2 (FHL2) serves as the anchor. FHL2 associates with O-GlcNAcylated TRAK and is both necessary and sufficient to drive the accumulation of F-actin around mitochondria and to arrest mitochondrial movement by anchoring to F-actin. Disruption of F-actin restores mitochondrial movement that had been arrested by either TRAK O-GlcNAcylation or forced direction of FHL2 to mitochondria. This pathway for mitochondrial immobilization is present in both neurons and non-neuronal cells and can thereby adapt mitochondrial dynamics to changes in glucose availability.

Trimers of the fibronectin cell adhesion domain localize to actin filament bundles and undergo rearward translocation

2002 ◽  
Vol 115 (12) ◽  
pp. 2581-2590 ◽  
Author(s):  
Françoise Coussen ◽  
Daniel Choquet ◽  
Michael P. Sheetz ◽  
Harold P. Erickson
Keyword(s):  
Cell Adhesion ◽  
Fluorescence Microscopy ◽  
Cell Surface ◽  
Actin Cytoskeleton ◽  
Fiber Bundles ◽  
Cell Surfaces ◽  
Actin Fiber ◽  
Filament Bundles ◽  
Necessary And Sufficient ◽  
Small Clusters

Previous studies have shown that small beads coated with FN7-10, a four-domain cell adhesion fragment of fibronectin, bind to cell surfaces and translocate rearward. Here we investigate whether soluble constructs containing two to five FN7-10 units might be sufficient for activity. We have produced a monomer, three forms of dimers, a trimer and a pentamer of FN7-10,on the end of spacer arms. These oligomers could bind small clusters of up to five integrins. Fluorescence microscopy showed that the trimer and pentamer bound strongly to the cell surface, and within 5 minutes were prominently localized to actin fiber bundles. Monomers and dimers showed only diffuse localization. Beads coated with a low concentration (probably one complex per bead) of trimer or pentamer showed prolonged binding and rearward translocation, presumably with the translocating actin cytskeleton. Beads containing monomer or dimer showed only brief binding and diffusive movements. We conclude that clusters of three integrin-binding ligands are necessary and sufficient for coupling to and translocating with the actin cytoskeleton.

scholarly journals Cbsoverdosage is necessary and sufficient to induce cognitive phenotypes in mouse models of Down syndrome and interacts genetically withDyrk1a

2018 ◽  
Author(s):  
Damien Marechal ◽  
Véronique Brault ◽  
Alice Leon ◽  
Dehren Martin ◽  
Patricia Lopes Pereira ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Object Recognition ◽  
Synaptic Transmission ◽  
Actin Cytoskeleton ◽  
Epistatic Interaction ◽  
Novel Object Recognition ◽  
The Novel ◽  
Novel Object ◽  
Cystathionine Beta Synthase ◽  
Necessary And Sufficient

ABSTRACTIdentifying dosage sensitive genes is a key to understand the mechanisms underlying intellectual disability in Down syndrome (DS). The Dp(17Abcg1-Cbs)1Yah DS mouse model (Dp1Yah) show cognitive phenotype and needs to be investigated to identify the main genetic driver. Here, we report that, in the Dp1Yah mice, 3 copies of the Cystathionine-beta-synthase gene (Cbs)are necessary to observe a deficit in the novel object recognition (NOR) paradigm. Moreover, the overexpression ofCbsalone is sufficient to induce NOR deficit. Accordingly targeting the overexpression of human CBS, specifically in Camk2a-expressing neurons, leads to impaired objects discrimination. Altogether this shows thatCbsoverdosage is involved in DS learning and memory phenotypes. In order to go further, we identified compounds that interfere with the phenotypical consequence of CBS overdosage in yeast. Pharmacological intervention in the Tg(CBS) with one selected compound restored memory in the novel object recognition. In addition, using a genetic approach, we demonstrated an epistatic interaction betweenCbsandDyrk1a, another human chromosome 21 gene encoding the dual-specificity tyrosine phosphorylation-regulated kinase 1a and an already known target for DS therapeutic intervention. Further analysis using proteomic approaches highlighted several pathways, including synaptic transmission, cell projection morphogenesis, and actin cytoskeleton, that are affected by DYRK1A and CBS overexpression. Overall we demonstrated that CBS overdosage underpins the DS-related recognition memory deficit and that bothCBSandDYRK1Ainteract to control accurate memory processes in DS. In addition, our study establishes CBS as an intervention point for treating intellectual deficiencies linked to DS.SIGNIFICANT STATEMENTHere, we investigated a region homologous to Hsa21 and located on mouse chromosome 17. We demonstrated using three independent genetic approaches that the overdosage of the Cystathionine-beta-synthase gene (Cbs) gene, encoded in the segment, is necessary and sufficient to induce deficit in novel object recognition (NR).In addition, we identified compounds that interfere with the phenotypical consequence of CBS overdosage in yeast and in mouse transgenic lines. Then we analyzed the relation between Cbs overdosage and the consequence of DYRK1a overexpression, a main driver of another region homologous to Hsa21 and we demonstrated that an epistatic interaction exist betweenCbsandDyrk1aaffecting different pathways, including synaptic transmission, cell projection morphogenesis, and actin cytoskeleton.

scholarly journals Mechanosensing through direct binding of tensed F-actin by LIM domains

2020 ◽  
Author(s):  
Xiaoyu Sun ◽  
Donovan Y. Z. Phua ◽  
Lucas Axiotakis ◽  
Mark A. Smith ◽  
Elizabeth Blankman ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Point Mutations ◽  
Cytoskeletal Proteins ◽  
Actin Binding ◽  
General Mechanism ◽  
Protein Protein Interaction ◽  
Cytoplasmic Actin ◽  
Lim Domains ◽  
Lim Proteins

SummaryMechanical signals transmitted through the cytoplasmic actin cytoskeleton must be relayed to the nucleus to control gene expression. LIM domains are protein-protein interaction modules found in cytoskeletal proteins and transcriptional regulators; however, it is unclear if there is a direct link between these two functions. Here we identify three LIM protein families (zyxin, paxillin, and FHL) whose members preferentially localize to the actin cytoskeleton in mechanically-stimulated cells through their tandem LIM domains. A minimal actin-myosin reconstitution system reveals that representatives of all three families directly bind F-actin only in the presence of mechanical force. Point mutations at a site conserved in each LIM domain of these proteins selectively disrupt tensed F-actin binding in vitro and cytoskeletal localization in cells, demonstrating a common, avidity-based mechanism. Finally, we find that binding to tensed F-actin in the cytoplasm excludes the cancer-associated transcriptional co-activator FHL2 from the nucleus in stiff microenvironments. This establishes direct force-activated F-actin binding by FHL2 as a mechanosensing mechanism. Our studies suggest that force-dependent sequestration of LIM proteins on the actin cytoskeleton could be a general mechanism for controlling nuclear localization to effect mechanical signaling.

scholarly journals Evolutionarily diverse LIM domain-containing proteins bind stressed actin filaments through a conserved mechanism

2020 ◽  
Vol 117 (41) ◽  
pp. 25532-25542 ◽  
Author(s):  
Jonathan D. Winkelman ◽  
Caitlin A. Anderson ◽  
Cristian Suarez ◽  
David R. Kovar ◽  
Margaret L. Gardel
Keyword(s):  
Actin Cytoskeleton ◽  
Fission Yeast ◽  
Actin Filaments ◽  
Mammalian Cells ◽  
Strain Sensing ◽  
Lim Domain ◽  
Lim Domains ◽  
Mechanical Homeostasis ◽  
Functionally Diverse

The actin cytoskeleton assembles into diverse load-bearing networks, including stress fibers (SFs), muscle sarcomeres, and the cytokinetic ring to both generate and sense mechanical forces. The LIM (Lin11, Isl- 1, and Mec-3) domain family is functionally diverse, but most members can associate with the actin cytoskeleton with apparent force sensitivity. Zyxin rapidly localizes via its LIM domains to failing SFs in cells, known as strain sites, to initiate SF repair and maintain mechanical homeostasis. The mechanism by which these LIM domains associate with stress fiber strain sites (SFSS) is not known. Additionally, it is unknown how widespread strain sensing is within the LIM protein family. We identify that the LIM domain-containing region of 18 proteins from the Zyxin, Paxillin, Tes, and Enigma proteins accumulate to SFSS. Moreover, the LIM domain region from the fission yeast protein paxillin like 1 (Pxl1) also localizes to SFSS in mammalian cells, suggesting that the strain sensing mechanism is ancient and highly conserved. We then used sequence and domain analysis to demonstrate that tandem LIM domains contribute additively, for SFSS localization. Employing in vitro reconstitution, we show that the LIM domain-containing region from mammalian zyxin and fission yeast Pxl1 binds to mechanically stressed F-actin networks but does not associate with relaxed actin filaments. We propose that tandem LIM domains recognize an F-actin conformation that is rare in the relaxed state but is enriched in the presence of mechanical stress.

scholarly journals Interaction between Mitochondria and the Actin Cytoskeleton in Budding Yeast Requires Two Integral Mitochondrial Outer Membrane Proteins, Mmm1p and Mdm10p

1998 ◽  
Vol 141 (6) ◽  
pp. 1371-1381 ◽  
Author(s):  
Istvan Boldogh ◽  
Nikola Vojtov ◽  
Sharon Karmon ◽  
Liza A. Pon
Keyword(s):  
Membrane Proteins ◽  
Actin Cytoskeleton ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Protein S ◽  
Binding Activity ◽  
Actin Binding ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Movement ◽  
Mitochondrial Motility

Transfer of mitochondria to daughter cells during yeast cell division is essential for viable progeny. The actin cytoskeleton is required for this process, potentially as a track to direct mitochondrial movement into the bud. Sedimentation assays reveal two different components required for mitochondria–actin interactions: (1) mitochondrial actin binding protein(s) (mABP), a peripheral mitochondrial outer membrane protein(s) with ATP-sensitive actin binding activity, and (2) a salt-inextractable, presumably integral, membrane protein(s) required for docking of mABP on the organelle. mABP activity is abolished by treatment of mitochondria with high salt. Addition of either the salt-extracted mitochondrial peripheral membrane proteins (SE), or a protein fraction with ATP-sensitive actin-binding activity isolated from SE, to salt-washed mitochondria restores this activity. mABP docking activity is saturable, resistant to high salt, and inhibited by pre-treatment of salt-washed mitochondria with papain. Two integral mitochondrial outer membrane proteins, Mmm1p (Burgess, S.M., M. Delannoy, and R.E. Jensen. 1994. J.Cell Biol. 126:1375–1391) and Mdm10p, (Sogo, L.F., and M.P. Yaffe. 1994. J.Cell Biol. 126:1361– 1373) are required for these actin–mitochondria interactions. Mitochondria isolated from an mmm1-1 temperature-sensitive mutant or from an mdm10 deletion mutant show no mABP activity and no mABP docking activity. Consistent with this, mitochondrial motility in vivo in mmm1-1 and mdm10Δ mutants appears to be actin independent. Depolymerization of F-actin using latrunculin-A results in loss of long-distance, linear movement and a fivefold decrease in the velocity of mitochondrial movement. Mitochondrial motility in mmm1-1 and mdm10Δ mutants is indistinguishable from that in latrunculin-A–treated wild-type cells. We propose that Mmm1p and Mdm10p are required for docking of mABP on the surface of yeast mitochondria and coupling the organelle to the actin cytoskeleton.

scholarly journals Phosphorylation of Ago2 and Subsequent Inactivation of let-7a RNP-Specific MicroRNAs Control Differentiation of Mammalian Sympathetic Neurons

2016 ◽  
Vol 36 (8) ◽  
pp. 1260-1271 ◽  
Author(s):  
Somi Patranabis ◽  
Suvendra Nath Bhattacharyya
Keyword(s):  
Protein Kinase ◽  
Neuronal Differentiation ◽  
Sympathetic Neurons ◽  
Neuronal Cells ◽  
Cellular Level ◽  
Mitogen Activated Protein Kinase ◽  
Animal Cells ◽  
Mitogen Activated Protein ◽  
Small Regulatory Rnas ◽  
Necessary And Sufficient

MicroRNAs (miRNAs) are small regulatory RNAs that regulate gene expression posttranscriptionally by base pairing to the target mRNAs in animal cells.KRas, an oncogene known to be repressed by let-7a miRNAs, is expressed and needed for the differentiation of mammalian sympathetic neurons and PC12 cells. We documented a loss of let-7a activity during this differentiation process without any significant change in the cellular level of let-7a miRNA. However, the level of Ago2, an essential component that is associated with miRNAs to form RNP-specific miRNA (miRNP) complexes, shows an increase with neuronal differentiation. In this study, differentiation-induced phosphorylation and the subsequent loss of miRNA from Ago2 were noted, and these accounted for the loss of miRNA activity in differentiating neurons. Neuronal differentiation induces the phosphorylation of mitogen-activated protein kinase p38 and the downstream kinase mitogen- and stress-activated protein kinase 1 (MSK1). This in turn upregulates the phosphorylation of Ago2 and ensures the dissociation of miRNA from Ago2 in neuronal cells. MSK1-mediated miRNP inactivation is a prerequisite for the differentiation of neuronal cells, where let-7a miRNA gets unloaded from Ago2 to ensure the upregulation ofKRas, a target of let-7a. We noted that the inactivation of let-7a is both necessary and sufficient for the differentiation of sympathetic neurons.

scholarly journals Ethanol-activated CaMKII signaling induces neuronal apoptosis through Drp1-mediated excessive mitochondrial fission and JNK1-dependent NLRP3 inflammasome activation.

2019 ◽  
Author(s):  
Jae Ryong Lim ◽  
Hyun Jik Lee ◽  
Young Hyun Jung ◽  
Jun Sung Kim ◽  
Chang Woo Chae ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Nlrp3 Inflammasome ◽  
Neuronal Apoptosis ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Neuronal Cells ◽  
Calcium Overload ◽  
Inflammasome Activation ◽  
Nlrp3 Inflammasome Activation ◽  
Ros Accumulation

Abstract Background: Neurodegeneration is a representative phenotype of patients with chronic alcoholism. Ethanol-induced calcium overload causes NLRP3 inflammasome formation and an imbalance in mitochondrial dynamics, closely associated with the pathogenesis of neurodegeneration. However, how calcium regulates this process in neuronal cells is poorly understood. Therefore, the present study investigated the detailed mechanism of calcium-regulated mitochondrial dynamics and NLRP3 inflammasome formation in neuronal cells by ethanol. Methods: In this study, we used the SK-N-MC human neuroblastoma cell line. To confirm the expression level of the mRNA and protein, real time quantitative PCR and western blot were performed. Co-immunoprecipitation and Immunofluorescence staining were conducted to confirm the complex formation or interaction of the proteins. Flow cytometry was used to analyze intracellular calcium, mitochondrial dysfunction and neuronal apoptosis. Results: Ethanol increased cleaved caspase-3 levels and mitochondrial reactive oxygen species (ROS) generation associated with neuronal apoptosis. In addition, ethanol increased PKA activation and CREB phosphorylation, which increased NMDA receptor (NMDAR) expression. Ethanol-increased NMDAR induced intracellular calcium overload and CaMKII activation leading to phosphorylation of dynamin-related protein 1 (Drp1) and JNK1. Drp1 phosphorylation promoted Drp1 translocation to the mitochondria, resulting in excessive mitochondrial fission, mitochondrial ROS accumulation, and loss of mitochondrial membrane potential, which was recovered by Drp1 inhibitor pretreatment. Ethanol-induced JNK1 phosphorylation activated the NLRP3 inflammasome that induced caspase-1 dependent mitophagy inhibition, thereby exacerbating ROS accumulation and causing cell death. Suppressing caspase-1 induced mitophagy and reversed the ethanol-induced apoptosis in neuronal cells. Conclusions: Our results demonstrated that ethanol upregulated NMDAR-dependent CaMKII phosphorylation which is essential for Drp1-mediated excessive mitochondrial fission and the JNK1-induced NLRP3 inflammasome activation resulting in neuronal apoptosis.

scholarly journals Ethanol-activated CaMKII signaling induces neuronal apoptosis through Drp1-mediated excessive mitochondrial fission and JNK1-dependent NLRP3 inflammasome activation.

2020 ◽  
Author(s):  
Jae Ryong Lim ◽  
Hyun Jik Lee ◽  
Young Hyun Jung ◽  
Jun Sung Kim ◽  
Chang Woo Chae ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Nlrp3 Inflammasome ◽  
Neuronal Apoptosis ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Neuronal Cells ◽  
Calcium Overload ◽  
Inflammasome Activation ◽  
Nlrp3 Inflammasome Activation ◽  
Ros Accumulation

Abstract Background: Neurodegeneration is a representative phenotype of patients with chronic alcoholism. Ethanol-induced calcium overload causes NLRP3 inflammasome formation and an imbalance in mitochondrial dynamics, closely associated with the pathogenesis of neurodegeneration. However, how calcium regulates this process in neuronal cells is poorly understood. Therefore, the present study investigated the detailed mechanism of calcium-regulated mitochondrial dynamics and NLRP3 inflammasome formation in neuronal cells by ethanol. Methods: In this study, we used the SK-N-MC human neuroblastoma cell line. To confirm the expression level of the mRNA and protein, real time quantitative PCR and western blot were performed. Co-immunoprecipitation and Immunofluorescence staining were conducted to confirm the complex formation or interaction of the proteins. Flow cytometry was used to analyze intracellular calcium, mitochondrial dysfunction and neuronal apoptosis. Results: Ethanol increased cleaved caspase-3 levels and mitochondrial reactive oxygen species (ROS) generation associated with neuronal apoptosis. In addition, ethanol increased PKA activation and CREB phosphorylation, which increased NMDA receptor (NMDAR) expression. Ethanol-increased NMDAR induced intracellular calcium overload and CaMKII activation leading to phosphorylation of dynamin-related protein 1 (Drp1) and JNK1. Drp1 phosphorylation promoted Drp1 translocation to the mitochondria, resulting in excessive mitochondrial fission, mitochondrial ROS accumulation, and loss of mitochondrial membrane potential, which was recovered by Drp1 inhibitor pretreatment. Ethanol-induced JNK1 phosphorylation activated the NLRP3 inflammasome that induced caspase-1 dependent mitophagy inhibition, thereby exacerbating ROS accumulation and causing cell death. Suppressing caspase-1 induced mitophagy and reversed the ethanol-induced apoptosis in neuronal cells. Conclusions: Our results demonstrated that ethanol upregulated NMDAR-dependent CaMKII phosphorylation which is essential for Drp1-mediated excessive mitochondrial fission and the JNK1-induced NLRP3 inflammasome activation resulting in neuronal apoptosis.

scholarly journals Nucleocytoplasmic Shuttling of the Cdc42p Exchange Factor Cdc24p

2000 ◽  
Vol 148 (6) ◽  
pp. 1115-1122 ◽  
Author(s):  
Aljoscha Nern ◽  
Robert A. Arkowitz
Keyword(s):  
Cell Cycle ◽  
Actin Cytoskeleton ◽  
Nuclear Import ◽  
Vegetative Growth ◽  
Nuclear Export ◽  
Nuclear Accumulation ◽  
Nucleocytoplasmic Shuttling ◽  
Exchange Factor ◽  
Cycle Dependent ◽  
Necessary And Sufficient

Cdc24p, the GDP/GTP exchange factor for the regulator of actin cytoskeleton Cdc42p, localizes to sites of polarized growth. Here we show that Cdc24p shuttles in and out of the yeast nucleus during vegetative growth. Far1p is necessary and sufficient for nuclear accumulation of Cdc24p, suggesting that its nuclear import occurs via an association with Far1p. Nuclear export is triggered either by entry into the cell cycle or by mating pheromone. As Far1p is degraded upon entry into the cell cycle, cell cycle–dependent export of Cdc24p occurs in the absence of Far1p, whereas during mating similar export kinetics indicate that a Cdc24p–Far1p complex is exported. Our results suggest that the nucleus serves as a store of preformed Cdc24p–Far1p complex which is required for chemotropism.

A cytoskeletal anchor connects ischemic mitochondrial fission to myocardial senescence

2018 ◽  
Vol 11 (556) ◽  
pp. eaav3267 ◽  
Author(s):  
Michael J. Boyer ◽  
Satoru Eguchi
Keyword(s):  
Myocardial Infarction ◽  
Actin Cytoskeleton ◽  
Physiological Function ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Tissue Homeostasis ◽  
Filamin A

The interplay between the actin cytoskeleton and mitochondria has been implicated in cell and tissue homeostasis and physiological function. In this issue of Science Signaling, Nishimura et al. demonstrate that inhibiting the interaction of filamin A, an actin cytoskeleton regulator, with Drp1, a modulator of mitochondrial dynamics, attenuates mitochondrial hyperfission and cardiomyocyte senescence after myocardial infarction.

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