Regulation of Mitochondrial Function by the Actin Cytoskeleton

α-Actinin-1 deficiency in megakaryocytes causes low platelet count, platelet dysfunction, and mitochondrial impairment

ABSTRACT

Cytoskeletal remodeling and mitochondrial bioenergetics play important roles in thrombocytopoiesis and platelet function. Recently, α-actinin-1 mutations have been reported in patients with congenital macrothrombocytopenia. However, the role and underlying mechanism of α-actinin-1 in thrombocytopoiesis and platelet function remain elusive. Using megakaryocyte (MK)-specific α-actinin-1 knockout (KO; PF4-Actn1-/-) mice, we demonstrated that PF4-Actn1-/- mice exhibited reduced platelet counts. The decreased platelet number in PF4-Actn1-/- mice was due to defects in thrombocytopoiesis. Hematoxylin and eosin staining and flow cytometry revealed a decrease in the number of MKs in the bone marrow of PF4-Actn1-/- mice. The absence of α-actinin-1 increased the proportion of 2 N-4 N MKs and decreased the proportion of 8 N-32 N MKs. Colony-forming unit-MK colony formation, the ratio of proplatelet formation-bearing MKs, and MK migration in response to stromal cell-derived factor-1 signaling were inhibited in PF4-Actn1-/- mice. Platelet spreading, clot retraction, aggregation, integrin αIIbβ3 activation, and CD62P exposure in response to various agonists were decreased in PF4-Actn1-/- platelets. Notably, PF4-Actn1-/- platelets inhibited calcium mobilization, reactive oxygen species (ROS) generation, and actin polymerization in response to collagen and thrombin. Furthermore, the PF4-Actn1-/- mice exhibited impaired hemostasis and thrombosis. Mechanistically, proteomic analysis of low-ploidy (2-4 N) and high-ploidy (≥8 N) PF4-Actn1-/- MKs revealed that α-actinin-1 deletion reduced platelet activation and mitochondrial function. PF4-Actn1-/- platelets and Actn1 KO 293T cells exhibited reduced mitochondrial membrane potential, mitochondrial ROS generation, mitochondrial calcium mobilization, and mitochondrial bioenergetics. Overall, in this study, we report that mice with α-actinin-1 deficiency in MKs exhibit low platelet count and impaired platelet function, thrombosis, and mitochondrial bioenergetics.

Integrin-Linked Kinase (ILK) Promotes Mitochondrial Dysfunction by Decreasing CPT1A Expression in a Folic Acid-Based Model of Kidney Disease

Integrin-linked kinase (ILK) is a key scaffolding protein between extracellular matrix protein and the cytoskeleton and has been implicated previously in the pathogenesis of renal damage. However, its involvement in renal mitochondrial dysfunction remains to be elucidated. We studied the role of ILK and its downstream regulations in renal damage and mitochondria function both in vivo and vitro, using a folic acid (FA)-induced kidney disease model. Wild type (WT) and ILK conditional-knockdown (cKD-ILK) mice were injected with a single intraperitoneal dose of FA and studied after 15 days of chronic renal damage progression. Human Kidney tubular epithelial cells (HK2) were transfected with specific siRNAs targeting ILK, glycogen synthase kinase 3-β (GSK3β), or CCAAT/enhancer binding protein-β (C/EBPβ). The expressions and activities of renal ILK, GSK3β, C/EBPβ, mitochondrial oxidative phosphorylation enzymes, and mitochondrial membrane potential were assessed. Additionally, the expression of markers for fibrosis fibronectin (FN) and collagen 1 (COL1A1), for autophagy p62 and cytosolic light chain 3 (LC3B) isoforms II and I, and mitochondrial homeostasis marker carnitine palmitoyl-transferase 1A (CPT1A) were evaluated using immunoblotting, RT-qPCR, immunofluorescence, or colorimetric assays. FA upregulated ILK expression, leading to the decrease of GSK3β activity, increased tubular fibrosis, and produced mitochondrial dysfunction, both in vivo and vitro. These alterations were fully or partially reversed upon ILK depletion, mitigating FA-induced renal damage. The signaling axis composed by ILK, GSK3β, and C/EBPβ regulated CPT1A transcription as the limiting factor in the FA-based impaired mitochondrial activity. We highlight ILK as a potential therapeutical target for preserving mitochondrial function in kidney injury.

Iron Accumulation and Lipid Peroxidation in Cellular Models of Nemaline Myopathies

One of the most prevalent types of congenital myopathy is nemaline myopathy (NM), which is recognized by histopathological examination of muscle fibers for the presence of "nemaline bodies" (rods). Mutations in the actin alpha 1 (ACTA1) and nebulin (NEB) genes result in the most prevalent types of NM. Muscle weakness and hypotonia are the main clinical characteristics of this disease. Unfortunately, the pathogenetic mechanisms are still unknown, and there is no cure. In previous work, we showed that actin filament polymerization defects in patient-derived fibroblasts were associated with mitochondrial dysfunction. In this manuscript, we examined the pathophysiological consequences of mitochondrial dysfunction in patient-derived fibroblasts. We analyzed iron and lipofuscin accumulation and lipid peroxidation both at the cellular and mitochondrial level. We found that fibroblasts derived from patients harboring ACTA1 and NEB mutations showed intracellular iron and lipofuscin accumulation, increased lipid peroxidation, and altered expression levels of proteins involved in iron metabolism. Furthermore, we showed that actin polymerization inhibition in control cells recapitulates the main pathological alterations of mutant nemaline cells. Our results indicate that mitochondrial dysfunction is associated with iron metabolism dysregulation, leading to iron/lipofuscin accumulation and increased lipid peroxidation.

Research progress of mitochondria and cytoskeleton crosstalk in tumour development

During tumour progression, organelle function undergoes dramatic changes, and crosstalk among organelles plays a significant role. Crosstalk between mitochondria and other organelles such as the endoplasmic reticulum and cytoskeleton has focussed attention on the mechanisms of tumourigenesis. This review demonstrates an overview of the molecular structure of the mitochondrial-cytoskeletal junction and its biological interactions. It also presents a detailed and comprehensive description of mitochondrial-cytoskeletal crosstalk in tumour occurrence and development, including tumour cell proliferation, apoptosis, autophagy, metabolic rearrangement, and metastasis. Finally, the application of crosstalk in tumour therapy, including drug combinations and chemoresistance, is discussed. This review offers a theoretical basis for establishing mitochondrial-cytoskeletal junctions as therapeutic targets, and offers novel insights into the future management of malignant tumours.

[Mechanism of WAVE1 regulation of lipopolysaccharide-induced mitochondrial metabolic abnormalities and inflammatory responses in macrophages]

OBJECTIVES

To explore the mechanism by which Wiskott-Aldrich syndrome protein family verprolin-homologous protein 1 (WAVE1) regulates lipopolysaccharide (LPS)-induced mitochondrial metabolic abnormalities and inflammatory responses in macrophages.

METHODS

Macrophage cell lines with overexpressed WAVE1 (mouse BMDM and human THP1 cells) were prepared. The macrophages were treated with LPS (500 ng/mL) to simulate sepsis-induced inflammatory responses. The experiment consisted of two parts. The first part included control, LPS, vector (LPS+oe-NC), WAVE1 overexpression (LPS+oe-WAVE1) groups. The second part included LPS, LPS+oe-NC, LPS+oe-WAVE1 and exogenous high mobility group box-1 (HMGB1) intervention (LPS+oe-WAVE1+HMGB1) groups. RT-PCR was used to measure mitochondrial DNA content, and RT-qPCR was used to detect the mRNA expression levels of WAVE1, tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6. Western blot was performed to measure the protein expression of WAVE1, hexokinase 2, and pyruvate kinase M2. ELISA was utilized to detect the levels of TNF-α, IL-1β, IL-6, and HMGB1. JC-1 staining was used to assess mitochondrial membrane potential. Seahorse XP96 was used to evaluate oxygen consumption rate and extracellular acidification rate. MitoSOX probe was employed to measure mitochondrial reactive oxygen species levels, and 2-NBDG method was used to assess glucose uptake. Kits were used to measure pyruvate kinase activity, lactate, adenosine triphosphate (ATP), and HMGB1 levels.

RESULTS

Compared with the control group, the LPS group showed lower levels of WAVE1 protein and mRNA expression, mitochondrial membrane potential, oxygen consumption rate, and mitochondrial DNA content (P<0.05), while TNF-α, IL-1β, IL-6 levels and mRNA expression, mitochondrial reactive oxygen species, glucose uptake, lactate, ATP, hexokinase 2, and pyruvate kinase M2 protein expression levels as well as extracellular acidification rate, pyruvate kinase activity, and HMGB1 release were significantly increased (P<0.05). Compared with the LPS+oe-NC group, the LPS+oe-WAVE1 group showed increased WAVE1 protein and mRNA expression, mitochondrial membrane potential, oxygen consumption rate, and mitochondrial DNA content (P<0.05), while TNF-α, IL-1β, IL-6 levels and mRNA expression, mitochondrial reactive oxygen species, glucose uptake, lactate, ATP, hexokinase 2, and pyruvate kinase M2 protein expressions, as well as extracellular acidification rate, pyruvate kinase activity, and HMGB1 release were decreased (P<0.05). Compared with the LPS+oe-WAVE1 group, the LPS+oe-WAVE1+HMGB1 group exhibited increased glucose uptake, lactate, ATP levels, and extracellular acidification rate (P<0.05).

CONCLUSIONS

WAVE1 participates in the regulation of LPS-induced inflammatory responses in macrophages by modulating the release of inflammatory factors, mitochondrial metabolism, and HMGB1 release.

Impairment of Intermediate Filament Expression Reveals Impact on Cell Functions Independent from Keratinocyte Transformation

Although cytoplasmic intermediate filaments (cIFs) are essential for cell physiology, the molecular and cell functional consequences of cIF disturbances are poorly understood. Identifying defaults in cell function-controlled tissue homeostasis and understanding the interrelationship between specific cIFs and distinct cell functions remain key challenges. Using an RNAi-based mechanistic approach, we connected the impairment of cell-inherent cIFs with molecular and cell functional consequences, such as proliferation and differentiation. To investigate cIF disruption consequences in the oral epithelium, different cell transformation stages, originating from alcohol-treated oral gingival keratinocytes, were used. We found that impairment of keratin (KRT) KRT5, KRT14 and vimentin (VIM) affects proliferation and differentiation, and modulates the chromatin status. Furthermore, cIF impairment reduces the expression of nuclear integrity participant lamin B1 and the terminal keratinocyte differentiation marker involucrin (IVL). Conversely, impairment of IVL reduces cIF expression levels, functionally suggesting a regulatory interaction between cIFs and IVL. The findings demonstrate that the impairment of cIFs leads to imbalances in proliferation and differentiation, both of which are essential for tissue homeostasis. Thus, targeted impairment of cIFs appears promising to investigate the functional role of cIFs on cell-dependent tissue physiology at the molecular level and identifies putative interactions of cIFs with epithelial differentiation.

HSF-1 promotes longevity through ubiquilin-1-dependent mitochondrial network remodelling

Increased activity of the heat shock factor, HSF-1, suppresses proteotoxicity and enhances longevity. However, the precise mechanisms by which HSF-1 promotes lifespan are unclear. Using an RNAi screen, we identify ubiquilin-1 (ubql-1) as an essential mediator of lifespan extension in worms overexpressing hsf-1. We find that hsf-1 overexpression leads to transcriptional downregulation of all components of the CDC-48-UFD-1-NPL-4 complex, which is central to both endoplasmic reticulum and mitochondria associated protein degradation, and that this is complemented by UBQL-1-dependent turnover of NPL-4.1. As a consequence, mitochondrial network dynamics are altered, leading to increased lifespan. Together, our data establish that HSF-1 mediates lifespan extension through mitochondrial network adaptations that occur in response to down-tuning of components associated with organellar protein degradation pathways.

The influences of ApoE isoforms on endothelial adherens junctions and actin cytoskeleton responding to mCRP

Apolipoprotein E4 (ApoE4) plays an important role responding to monomeric C-reactive protein (mCRP) via binding to CD31 leading to cerebrovascular damage and Alzheimer's disease (AD). Using phosphor-proteomic profiling, we found altered cytoskeleton proteins in the microvasculature of AD brains, including increased levels of hyperphosphorylated tau (pTau) and the actin-related protein, LIMA1. To address the hypothesis that cytoskeletal changes serve as early pathological signatures linked with CD31 in brain endothelia in ApoE4 carriers, ApoE4 knock-in mice intraperitoneal injected with mCRP revealed that mCRP increased the expressions of phosphorylated CD31 (pCD31) and LIMA1, and facilitate the binding of pCD31 to LIMA1. mCRP combined with recombinant APOE4 protein decreased interaction of CD31 and VE-Cadherin at adherens junctions (AJs), along with altered the expression of various actin cytoskeleton proteins, causing microvasculature damage. Notably, the APOE2 protein attenuated these changes. Overall, our study demonstrates that ApoE4 responds to mCRP to disrupt the endothelial AJs which link with the actin cytoskeleton and this pathway could play a key role in the barrier dysfunction leading to AD risk.

Advancements in mitochondrial-targeted nanotherapeutics: overcoming biological obstacles and optimizing drug delivery

In recent decades, nanotechnology has significantly advanced drug delivery systems, particularly in targeting subcellular organelles, thus opening new avenues for disease treatment. Mitochondria, critical for cellular energy and health, when dysfunctional, contribute to cancer, neurodegenerative diseases, and metabolic disorders. This has propelled the development of nanomedicines aimed at precise mitochondrial targeting to modulate their function, marking a research hotspot. This review delves into the recent advancements in mitochondrial-targeted nanotherapeutics, with a comprehensive focus on targeting strategies, nanocarrier designs, and their therapeutic applications. It emphasizes nanotechnology's role in enhancing drug delivery by overcoming biological barriers and optimizing drug design for specific mitochondrial targeting. Strategies exploiting mitochondrial membrane potential differences and specific targeting ligands improve the delivery and mitochondrial accumulation of nanomedicines. The use of diverse nanocarriers, including liposomes, polymer nanoparticles, and inorganic nanoparticles, tailored for effective mitochondrial targeting, shows promise in anti-tumor and neurodegenerative treatments. The review addresses the challenges and future directions in mitochondrial targeting nanotherapy, highlighting the need for precision, reduced toxicity, and clinical validation. Mitochondrial targeting nanotherapy stands at the forefront of therapeutic strategies, offering innovative treatment perspectives. Ongoing innovation and research are crucial for developing more precise and effective treatment modalities.

Response to chronic sustained hypoxia: increased cytosolic gelsolin and decreased plasma gelsolin levels

An actin binding protein, gelsolin (GSN) has two isoforms, plasma (pGSN) and cytosolic (cGSN). Changes in pGSN and/or cGSN levels have been shown to be associated with the pathogenesis of several diseases. The aim of this study was to evaluate changes in intracellular and extracellular GSNlevels with HIF-1 in animals exposed to chronic sustained hypoxia (CSH), in addition to apoptosis and the cellular redox status. The rats in the Sham group were exposed to 21% O2, and the rats in the hypoxia groups were exposed to 13 and 10% O2, respectively. Plasma pGSN, HIF-1α, Total Antioxidant Status (TAS) and Total Oxidant Status (TOS), and lung tissue pGSN, HIF-1α, TAS, TOS, GSN levels, and apoptotic cell numbers were measured. HIF-1α levels were found to increase significantly in the tissue, especially in the group with severe hypoxia, both in biochemical and histological examinations. pGSN levels were also significantly decreased in both plasma and tissue. Significant increases in tissue were observed in cGSN. It was observed that while the antioxidant activity was dominant in the tissue, the oxidant activity was dominant in the plasma. In particular, the response to hypoxia regulated by HIF-1 is very important for cellular survival. The results of this study showed that the increase in cGSN and TAS levels in the lung tissue together with HIF-1α can be considered as the activation of mechanisms for cellular protection.

Synergistic Inhibition of Pancreatic Cancer Cell Growth and Migration by Gemcitabine and Withaferin A

Pancreatic cancer remains one of the most lethal malignancies due to its aggressive nature and resistance to conventional therapies. This study investigates the anti-proliferative, pro-apoptotic, and anti-migratory effects of Gemcitabine (GC) and Withaferin A (WFA) on pancreatic cancer cell lines PANC-1 and Hs766t. The MTS assay revealed that both compounds effectively inhibit cell proliferation, with WFA showing a stronger effect in Hs766t cells. Flow cytometry analysis demonstrated that GC and WFA, particularly in combination, significantly induce apoptosis in both cell lines. Migration assays confirmed the potent inhibition of cell migration by both compounds, with the combination treatment being the most effective. Furthermore, actin cytoskeleton analysis indicated substantial changes in cell morphology and stiffness, suggesting that GC and WFA disrupt the structural integrity of cancer cells. Additionally, the study highlights a ROS-mediated mechanism underlying the effects of GC and WFA, as evidenced by increased ROS levels following treatment, which were attenuated by N-acetylcysteine. Importantly, NF-κB activity was significantly modulated, with WFA reducing NF-κB activation induced by GC, potentially contributing to the synergistic pro-apoptotic effect of the combination. These findings suggest that the combination of GC and WFA may offer a synergistic therapeutic approach for treating pancreatic cancer by targeting multiple aspects of tumor cell behavior.

The actin binding protein profilin 1 localizes inside mitochondria and is critical for their function

The monomer-binding protein profilin 1 (PFN1) plays a crucial role in actin polymerization. However, mutations in PFN1 are also linked to hereditary amyotrophic lateral sclerosis, resulting in a broad range of cellular pathologies which cannot be explained by its primary function as a cytosolic actin assembly factor. This implies that there are important, undiscovered roles for PFN1 in cellular physiology. Here we screened knockout cells for novel phenotypes associated with PFN1 loss of function and discovered that mitophagy was significantly upregulated. Indeed, despite successful autophagosome formation, fusion with the lysosome, and activation of additional mitochondrial quality control pathways, PFN1 knockout cells accumulate depolarized, dysmorphic mitochondria with altered metabolic properties. Surprisingly, we also discovered that PFN1 is present inside mitochondria and provide evidence that mitochondrial defects associated with PFN1 loss are not caused by reduced actin polymerization in the cytosol. These findings suggest a previously unrecognized role for PFN1 in maintaining mitochondrial integrity and highlight new pathogenic mechanisms that can result from PFN1 dysregulation.

Beyond fission and fusion-Diving into the mysteries of mitochondrial shape

Mitochondrial shape and network formation have been primarily associated with the well-established processes of fission and fusion. However, recent research has unveiled an intricate and multifaceted landscape of mitochondrial morphology that extends far beyond the conventional fission-fusion paradigm. These less-explored dimensions harbor numerous unresolved mysteries. This review navigates through diverse processes influencing mitochondrial shape and network formation, highlighting the intriguing complexities and gaps in our understanding of mitochondrial architecture. The exploration encompasses various scales, from biophysical principles governing membrane dynamics to molecular machineries shaping mitochondria, presenting a roadmap for future research in this evolving field.

The interplay between mitochondrial dysfunction and NLRP3 inflammasome in multiple sclerosis: Therapeutic implications and animal model studies

Multiple sclerosis (MS) is a complex autoimmune disorder that impacts the central nervous system (CNS), resulting in inflammation, demyelination, and neurodegeneration. The NOD-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome, a multiprotein complex of the innate immune system, serves an essential role in the pathogenesis of MS by regulating the production of pro-inflammatory cytokines (IL-1β & IL-18) and the induction of pyroptotic cell death. Mitochondrial dysfunction is one of the main potential factors that can trigger NLRP3 inflammasome activation and lead to inflammation and axonal damage in MS. This highlights the importance of understanding how mitochondrial dynamics modulate NLRP3 inflammasome activity and contribute to the inflammatory and neurodegenerative features of MS. The lack of a comprehensive understanding of the pathogenesis of MS and the urge for the introduction of new therapeutic strategies led us to review the therapeutic potential of targeting the interplay between mitochondrial dysfunction and the NLRP3 inflammasome in MS. This paper also evaluates the natural and synthetic compounds that can improve mitochondrial function and/or inhibit the NLRP3 inflammasome, thereby providing neuroprotection. Moreover, it summarizes the evidence from animal models of MS that demonstrate the beneficial effects of these compounds on reducing inflammation, demyelination, and neurodegeneration. Finally, this review advocates for a deeper investigation into the molecular crosstalk between mitochondrial dynamics and the NLRP3 inflammasome as a means to refine therapeutic targets for MS.

A glimpse into cofilin-1 role in cancer therapy: A potential target to improve clinical outcomes?

Cofilin-1 (CFL1) modulates dynamic actin networks by severing and enhancing depolymerization. The upregulation of cofilin-1 expression in several cancer types is associated with tumor progression and metastasis. However, recent discoveries indicated relevant cofilin-1 functions under oxidative stress conditions, interplaying with mitochondrial dynamics, and apoptosis networks. In this scenario, these emerging roles might impact the response to clinical therapy and could be used to enhance treatment efficacy. Here, we highlight new perspectives of cofilin-1 in the therapy resistance context and discussed how cofilin-1 is involved in these events, exploring aspects of its contribution to therapeutic resistance. We also provide an analysis of CFL1 expression in several tumors predicting survival. Therefore, understanding how exactly coflin-1 plays, particularly in therapy resistance, may pave the way to the development of treatment strategies and improvement of patient survival.

The Remodulation of Actin Bundles during the Stimulation of Mitochondria in Adult Human Fibroblasts in Response to Light

β-actin belongs to cytoskeletal structures that change dynamically in cells according to various stimuli. Human skin can be considered as an organ that is very frequently exposed to various stress factors, of which light plays an important role. The present study focuses on adult human fibroblasts exposed to two types of light stress. Orange light with a wavelength of 590 nm was used here to stimulate the photosensitizer localized in the cells as a residual dose of photodynamic therapy (PDT). On the other hand, near-infrared light with a wavelength of 808 nm was considered for photobiomodulation (PBM), which is often used in healing processes. Confocal fluorescence microscopy was used to observe changes in intercellular communication, mitochondrial structures, and cytoskeletal dynamics defined by the remodulation of β-actin of fibroblasts. The number of β-actin bundles forming spherical structures was detected after light exposure. These structures as β-actin oligomers were confirmed with super-resolution microscopy. While PDT led to the disintegration of actin oligomers, PBM increased their number. The interaction of β-actin with mitochondria was observed. The combination of PDT and PBM treatments is important to minimize the side effects of cancer treatment with PDT on healthy cells, as shown by the cell metabolism assay in this work. In this work, β-actin is presented as an important parameter that changes and is involved in the response of cells to PDT and PBM.

Occidiofungin inhibition of Candida biofilm formation on silicone elastomer surface

IMPORTANCE

Candida are opportunistic fungal pathogens with medical relevance given their association with superficial to life-threatening infections. An important component of Candida virulence is the ability to form a biofilm. These structures are highly resistant to antifungal therapies and are often the cause of treatment failure. In this work, we evaluated the efficacy of the antifungal compound, occidiofungin, against Candida biofilms developed on a silicone surface. We demonstrate that occidiofungin eliminated cells at all stages of biofilm formation in a dose-dependent manner. Consistent with our understanding of occidiofungin bioactivity, we noted alterations to actin organization and cell morphology following antifungal exposure. Given the challenges associated with the treatment of biofilm-associated infections, occidiofungin exhibits potential as a therapeutic antifungal agent in the future.

GRAF1 integrates PINK1-Parkin signaling and actin dynamics to mediate cardiac mitochondrial homeostasis

The serine/threonine kinase, PINK1, and the E3 ubiquitin ligase, Parkin, are known to facilitate LC3-dependent autophagosomal encasement and lysosomal clearance of dysfunctional mitochondria, and defects in this process contribute to a variety of cardiometabolic and neurological diseases. Although recent evidence indicates that dynamic actin remodeling plays an important role in PINK1/Parkin-mediated mitochondrial autophagy (mitophagy), the underlying signaling mechanisms remain unknown. Here, we identify the RhoGAP GRAF1 (Arhgap26) as a PINK1 substrate that regulates mitophagy. GRAF1 promotes the release of damaged mitochondria from F-actin anchors, regulates mitochondrial-associated Arp2/3-mediated actin remodeling and facilitates Parkin-LC3 interactions to enhance mitochondria capture by autophagosomes. Graf1 phosphorylation on PINK1-dependent sites is dysregulated in human heart failure, and cardiomyocyte-restricted Graf1 depletion in mice blunts mitochondrial clearance and attenuates compensatory metabolic adaptations to stress. Overall, we identify GRAF1 as an enzyme that coordinates cytoskeletal and metabolic remodeling to promote cardioprotection.

Actin Polymerization Defects Induce Mitochondrial Dysfunction in Cellular Models of Nemaline Myopathies

Nemaline myopathy (NM) is one of the most common forms of congenital myopathy and it is identified by the presence of "nemaline bodies" (rods) in muscle fibers by histopathological examination. The most common forms of NM are caused by mutations in the Actin Alpha 1 (ACTA1) and Nebulin (NEB) genes. Clinical features include hypotonia and muscle weakness. Unfortunately, there is no curative treatment and the pathogenetic mechanisms remain unclear. In this manuscript, we examined the pathophysiological alterations in NM using dermal fibroblasts derived from patients with mutations in ACTA1 and NEB genes. Patients' fibroblasts were stained with rhodamine-phalloidin to analyze the polymerization of actin filaments by fluorescence microscopy. We found that patients' fibroblasts showed incorrect actin filament polymerization compared to control fibroblasts. Actin filament polymerization defects were associated with mitochondrial dysfunction. Furthermore, we identified two mitochondrial-boosting compounds, linoleic acid (LA) and L-carnitine (LCAR), that improved the formation of actin filaments in mutant fibroblasts and corrected mitochondrial bioenergetics. Our results indicate that cellular models can be useful to study the pathophysiological mechanisms involved in NM and to find new potential therapies. Furthermore, targeting mitochondrial dysfunction with LA and LCAR can revert the pathological alterations in NM cellular models.

Cdk12 maintains the integrity of adult axons by suppressing actin remodeling

The role of cyclin-dependent kinases (CDKs) that are ubiquitously expressed in the adult nervous system remains unclear. Cdk12 is enriched in terminally differentiated neurons where its conical role in the cell cycle progression is redundant. We find that in adult neurons Cdk12 acts a negative regulator of actin formation, mitochondrial dynamics and neuronal physiology. Cdk12 maintains the size of the axon at sites proximal to the cell body through the transcription of homeostatic enzymes in the 1-carbon by folate pathway which utilize the amino acid homocysteine. Loss of Cdk12 leads to elevated homocysteine and in turn leads to uncontrolled F-actin formation and axonal swelling. Actin remodeling further induces Drp1-dependent fission of mitochondria and the breakdown of axon-soma filtration barrier allowing soma restricted cargos to enter the axon. We demonstrate that Cdk12 is also an essential gene for long-term neuronal survival and loss of this gene causes age-dependent neurodegeneration. Hyperhomocysteinemia, actin changes, and mitochondrial fragmentation are associated with several neurodegenerative conditions such as Alzheimer's disease and we provide a candidate molecular pathway to link together such pathological events.

The actin binding protein profilin 1 is critical for mitochondria function

Profilin 1 (PFN1) is an actin binding protein that is vital for the polymerization of monomeric actin into filaments. Here we screened knockout cells for novel functions of PFN1 and discovered that mitophagy, a type of selective autophagy that removes defective or damaged mitochondria from the cell, was significantly upregulated in the absence of PFN1. Despite successful autophagosome formation and fusion with the lysosome, and activation of additional mitochondrial quality control pathways, PFN1 knockout cells still accumulate damaged, dysfunctional mitochondria. Subsequent imaging and functional assays showed that loss of PFN1 significantly affects mitochondria morphology, dynamics, and respiration. Further experiments revealed that PFN1 is located to the mitochondria matrix and is likely regulating mitochondria function from within rather than through polymerizing actin at the mitochondria surface. Finally, PFN1 mutants associated with amyotrophic lateral sclerosis (ALS) fail to rescue PFN1 knockout mitochondrial phenotypes and form aggregates within mitochondria, further perturbing them. Together, these results suggest a novel function for PFN1 in regulating mitochondria and identify a potential pathogenic mechanism of ALS-linked PFN1 variants.

A dynamic actin cytoskeleton is required to prevent constitutive VDAC-dependent MAPK signalling and aberrant lipid homeostasis

The dynamic nature of the actin cytoskeleton is required to coordinate many cellular processes, and a loss of its plasticity has been linked to accelerated cell aging and attenuation of adaptive response mechanisms. Cofilin is an actin-binding protein that controls actin dynamics and has been linked to mitochondrial signaling pathways that control drug resistance and cell death. Here we show that cofilin-driven chronic depolarization of the actin cytoskeleton activates cell wall integrity mitogen-activated protein kinase (MAPK) signalling and disrupts lipid homeostasis in a voltage-dependent anion channel (VDAC)-dependent manner. Expression of the cof1-5 mutation, which reduces the dynamic nature of actin, triggers loss of cell wall integrity, vacuole fragmentation, disruption of lipid homeostasis, lipid droplet (LD) accumulation, and the promotion of cell death. The integrity of the actin cytoskeleton is therefore essential to maintain the fidelity of MAPK signaling, lipid homeostasis, and cell health in S. cerevisiae.

Woven bone formation and mineralization by rat mesenchymal stromal cells imply increased expression of the intermediate filament desmin

Background

Disordered and hypomineralized woven bone formation by dysfunctional mesenchymal stromal cells (MSCs) characterize delayed fracture healing and endocrine -metabolic bone disorders like fibrous dysplasia and Paget disease of bone. To shed light on molecular players in osteoblast differentiation, woven bone formation, and mineralization by MSCs we looked at the intermediate filament desmin (DES) during the skeletogenic commitment of rat bone marrow MSCs (rBMSCs), where its bone-related action remains elusive.

Results

Monolayer cultures of immunophenotypically- and morphologically - characterized, adult male rBMSCs showed co-localization of desmin (DES) with vimentin, F-actin, and runx2 in all cell morphotypes, each contributing to sparse and dense colonies. Proteomic analysis of these cells revealed a topologically-relevant interactome, focused on cytoskeletal and related enzymes//chaperone/signalling molecules linking DES to runx2 and alkaline phosphatase (ALP). Osteogenic differentiation led to mineralized woven bone nodules confined to dense colonies, significantly smaller and more circular with respect to controls. It significantly increased also colony-forming efficiency and the number of DES-immunoreactive dense colonies, and immunostaining of co-localized DES/runx-2 and DES/ALP. These data confirmed pre-osteoblastic and osteoblastic differentiation, woven bone formation, and mineralization, supporting DES as a player in the molecular pathway leading to the osteogenic fate of rBMSCs.

Conclusion

Immunocytochemical and morphometric studies coupled with proteomic and bioinformatic analysis support the concept that DES may act as an upstream signal for the skeletogenic commitment of rBMSCs. Thus, we suggest that altered metabolism of osteoblasts, woven bone, and mineralization by dysfunctional BMSCs might early be revealed by changes in DES expression//levels. Non-union fractures and endocrine - metabolic bone disorders like fibrous dysplasia and Paget disease of bone might take advantage of this molecular evidence for their early diagnosis and follow-up.

Mitochondrial Volume Regulation and Swelling Mechanisms in Cardiomyocytes

Mitochondrion, known as the "powerhouse" of the cell, regulates ion homeostasis, redox state, cell proliferation and differentiation, and lipid synthesis. The inner mitochondrial membrane (IMM) controls mitochondrial metabolism and function. It possesses high levels of proteins that account for ~70% of the membrane mass and are involved in the electron transport chain, oxidative phosphorylation, energy transfer, and ion transport, among others. The mitochondrial matrix volume plays a crucial role in IMM remodeling. Several ion transport mechanisms, particularly K+ and Ca2+, regulate matrix volume. Small increases in matrix volume through IMM alterations can activate mitochondrial respiration, whereas excessive swelling can impair the IMM topology and initiates mitochondria-mediated cell death. The opening of mitochondrial permeability transition pores, the well-characterized phenomenon with unknown molecular identity, in low- and high-conductance modes are involved in physiological and pathological increases of matrix volume. Despite extensive studies, the precise mechanisms underlying changes in matrix volume and IMM structural remodeling in response to energy and oxidative stressors remain unknown. This review summarizes and discusses previous studies on the mechanisms involved in regulating mitochondrial matrix volume, IMM remodeling, and the crosstalk between these processes.

Enhanced mitochondrial fission inhibits triple-negative breast cancer cell migration through an ROS-dependent mechanism

Mitochondria produce reactive oxygen species (ROS), which function in signal transduction. Mitochondrial dynamics, encompassing morphological shifts between fission and fusion, can directly impact ROS levels in cancer cells. In this study, we identified an ROS-dependent mechanism for how enhanced mitochondrial fission inhibits triple negative breast cancer (TNBC) cell migration. We found that enforcing mitochondrial fission in TNBC resulted in an increase in intracellular ROS levels and reduced cell migration and the formation of actin-rich migratory structures. Consistent with mitochondrial fission, increasing ROS levels in cells inhibited cell migration. Conversely, reducing ROS levels with either a global or mitochondrially targeted scavenger overcame the inhibitory effects of mitochondrial fission. Mechanistically, we found that the ROS sensitive SHP-1/2 phosphatases partially regulate inhibitory effects of mitochondrial fission on TNBC migration. Overall, our work reveals the inhibitory effects of ROS in TNBC and supports mitochondrial dynamics as a potential therapeutic target for cancer.

Metabolic reprogramming of renal epithelial cells contributes to lithium-induced nephrogenic diabetes insipidus

Lithium, mainstay treatment for bipolar disorder, frequently causes nephrogenic diabetes insipidus (NDI) and renal injury. However, the detailed mechanism remains unclear. Here we used the analysis of metabolomics and transcriptomics and metabolic intervention in a lithium-induced NDI model. Mice were treated with lithium chloride (40 mmol/kg chow) and rotenone (ROT, 100 ppm) in diet for 28 days. Transmission electron microscopy showed extensive mitochondrial structural abnormalities in whole nephron. ROT treatment markedly ameliorated lithium-induced NDI and mitochondrial structural abnormalities. Moreover, ROT attenuated the decrease of mitochondrial membrane potential in line with the upregulation of mitochondrial genes in kidney. Metabolomics and transcriptomics data demonstrated that lithium activated galactose metabolism, glycolysis, and amino sugar and nucleotide sugar metabolism. All these events were indicative of metabolic reprogramming in kidney cells. Importantly, ROT ameliorated metabolic reprogramming in NDI model. Based on transcriptomics analysis, we also found the activation of MAPK, mTOR and PI3K-Akt signaling pathways and impaired focal adhesion, ECM-receptor interaction and actin cytoskeleton in Li-NDI model were inhibited or attenuated by ROT treatment. Meanwhile, ROT administration inhibited the increase of Reactive Oxygen Species (ROS) in NDI kidneys along with enhanced SOD2 expression. Finally, we observed that ROT partially restored reduced the reduced AQP2 and enhanced urinary sodium excretion along with the blockade of increased PGE2 output. Taken together, the current study demonstrates that mitochondrial abnormalities and metabolic reprogramming play a key role in lithium-induced NDI, as well as the dysregulated signaling pathways, thereby serving as a novel therapeutic target.

The Potent Antitumor Activity of Smp43 against Non-Small-Cell Lung Cancer A549 Cells via Inducing Membranolysis and Mitochondrial Dysfunction

Research has been conducted to investigate the potential application of scorpion venom-derived peptides in cancer therapy. Smp43, a cationic antimicrobial peptide from Scorpio maurus palmatus venom, has been found to exhibit suppressive activity against the proliferation of multiple cancer cell lines. However, its impact on non-small-cell lung cancer (NSCLC) cell lines has not been previously investigated. This study aimed to determine the cytotoxicity of Smp43 towards various NSCLC cell lines, particularly A549 cells with an IC₅₀ value of 2.58 μM. The results indicated that Smp43 was internalized into A549 cells through membranolysis and endocytosis, which caused cytoskeleton disorganization, a loss of mitochondrial membrane potential, an accumulation of reactive oxygen species (ROS), and abnormal apoptosis, cell cycle distribution, and autophagy due to mitochondrial dysfunction. Additionally, the study explored the in vivo protective effect of Smp43 in xenograft mice. The findings suggest that Smp43 has potential anticarcinoma properties exerted via the inducement of cellular processes related to cell membrane disruption and mitochondrial dysfunction.

MFN2 deficiency affects calcium homeostasis in lung adenocarcinoma cells via downregulation of UCP4

Mitofusin-2 (MFN2) is a transmembrane GTPase that regulates mitochondrial fusion and thereby modulates mitochondrial function. However, the role of MFN2 in lung adenocarcinoma remains controversial. Here, we investigated the effect of MFN2 regulation on mitochondria in lung adenocarcinoma. We found that MFN2 deficiency resulted in decreased UCP4 expression and mitochondrial dysfunction in A549 and H1975 cells. UCP4 overexpression restored ATP and intracellular calcium concentration, but not mtDNA copy number, mitochondrial membrane potential or reactive oxygen species level. Furthermore, mass spectrometry analysis identified 460 overlapping proteins after independent overexpression of MFN2 and UCP4; these proteins were significantly enriched in the cytoskeleton, energy production, and calponin homology (CH) domains. Moreover, the calcium signaling pathway was confirmed to be enriched in KEGG pathway analysis. We also found by protein-protein interaction network analysis that PINK1 may be a key regulator of MFN2- and UCP4-mediated calcium homeostasis. Furthermore, PINK1 increased MFN2/UCP4-mediated intracellular Ca²⁺ concentration in A549 and H1975 cells. Finally, we demonstrated that low expression levels of MFN2 and UCP4 in lung adenocarcinoma are associated with poor clinical prognosis. In conclusion, our data suggest not only a potential role of MFN2 and UCP4 in co-regulating calcium homeostasis in lung adenocarcinoma but also their potential use as therapeutic targets in lung cancer.

Drug-tolerant persister B-cell precursor acute lymphoblastic leukemia cells

Reduced responsiveness of precursor B-acute lymphoblastic leukemia (BCP-ALL) to chemotherapy can be inferred when leukemia cells persist after 28 days of initial treatment. Survival of these long-term persister (LTP) / minimal residual disease (MRD) cells is partly due to bone marrow stromal cells that protect them under conditions of chemotherapy stress. We used RNA-seq to analyse BCP-ALL cells that survived a long-term, 30-day vincristine chemotherapy treatment while in co-culture with bone marrow stromal cells. RNAs of as many as 10% of the protein-encoding genes were differentially expressed. There was substantial overlap with genes associated with MRD cell persistence reported in other studies. The top pathway regulated in the LTP cells was that involving p53, a master regulator of a spectrum of responses relevant to drug resistance and cytotoxic drug exposure including control of autophagy. We tested a select number of genes for contribution to BCP-ALL cell survival using Cas9/CRISPR in a 2-step selection, initially for overall effect on cell fitness, followed by 21 days of exposure to vincristine. Many genes involved in autophagy and lysosomal function were found to contribute to survival both at steady-state and during drug treatment. We also identified MYH9, NCSTN and KIAA2013 as specific genes contributing to fitness of BCP-ALL cells. CD44 was not essential for growth under steady state conditions but was needed for survival of vincristine treatment. Finally, although the drug transporter ABCC1/MRP1 is not overexpressed in BCP-ALL, a functional gene was needed for DTP cells to survive treatment with vincristine. This suggests that addition of possible ABCC1 inhibitors during induction therapy could provide benefit in eradication of minimal residual disease in patients treated with a chemotherapy regimen that includes vincristine.

Mitochondria Drive Immune Responses in Critical Disease

Mitochondria engage in multiple cellular and extracellular signaling pathways ranging from metabolic control, antiviral and antibacterial host defense to the modulation of inflammatory responses following cellular damage and stress. The remarkable contributions of these organelles to innate and adaptive immunity, shape cell phenotype and modulate their functions during infection, after trauma and in the setting of inflammatory disease. We review the latest knowledge of mitochondrial biology and then discuss how these organelles may impact immune cells to drive aberrant immune responses in critical disease.

Microbial-derived metabolites induce actin cytoskeletal rearrangement and protect blood-brain barrier function

The gut microbiota influences host brain function, but the underlying gut-brain axis connections and molecular processes remain unclear. One pathway along this bidirectional communication system involves circulating microbially derived metabolites, such as short-chain fatty acids (SCFAs), which include butyrate and propionate. Brain endothelium is the main interface of communication between circulating signals and the brain, and it constitutes the main component of the blood-brain barrier (BBB). Here, we used a well-established in vitro BBB model treated with physiologically relevant concentrations of butyrate and propionate with and without lipopolysaccharide (LPS) to examine the effects of SCFAs on the actin cytoskeleton and tight junction protein structure. Both SCFAs induced distinct alterations to filamentous actin directionality. SCFAs also increased tight junction protein spikes and protected from LPS-induced tight-junction mis-localization, improved BBB integrity, and modulated mitochondrial network dynamics. These findings identify the actin cytoskeletal dynamics as another target further illuminating how SCFAs can influence BBB physiology.

Smp24, a Scorpion-Venom Peptide, Exhibits Potent Antitumor Effects against Hepatoma HepG2 Cells via Multi-Mechanisms In Vivo and In Vitro

Scorpion-venom-derived peptides have become a promising anticancer agent due to their cytotoxicity against tumor cells via multiple mechanisms. The suppressive effect of the cationic antimicrobial peptide Smp24, which is derived from the venom of ScorpioMaurus palmatus, on the proliferation of the hepatoma cell line HepG2 has been reported earlier. However, its mode of action against HepG2 hepatoma cells remains unclear. In the current research, Smp24 was discovered to suppress the viability of HepG2 cells while having a minor effect on normal LO2 cells. Moreover, endocytosis and pore formation were demonstrated to be involved in the uptake of Smp24 into HepG2 cells, which subsequently interacted with the mitochondrial membrane and caused the decrease in its potential, cytoskeleton reorganization, ROS accumulation, mitochondrial dysfunction, and alteration of apoptosis- and autophagy-related signaling pathways. The protecting activity of Smp24 in the HepG2 xenograft mice model was also demonstrated. Therefore, our data suggest that the antitumor effect of Smp24 is closely related to the induction of cell apoptosis, cycle arrest, and autophagy via cell membrane disruption and mitochondrial dysfunction, suggesting a potential alternative in hepatocellular carcinoma treatment.

Evidence of a role for cAMP in mitochondrial regulation in ovarian granulosa cells

In the ovary, proliferation and differentiation of granulosa cells (GCs) drive follicular growth. Our immunohistochemical study in a non-human primate, the Rhesus monkey, showed that the mitochondrial activity marker protein cytochrome c oxidase subunit 4 (COX4) increases in GCs in parallel to follicle size, and furthermore, its intracellular localization changes. This suggested that there is mitochondrial biogenesis and trafficking, and implicates the actions of gonadotropins, which regulate follicular growth and ovulation. Human KGN cells, i.e. granulosa tumour cells, were therefore used to study these possibilities. To robustly elevate cAMP, and thereby mimic the actions of gonadotropins, we used forskolin (FSK). FSK increased the cell size and the amount of mitochondrial DNA of KGN cells within 24 h. As revealed by MitoTracker™ experiments and ultrastructural 3D reconstruction, FSK treatment induced the formation of elaborate mitochondrial networks. H89, a protein kinase A (PKA) inhibitor, reduced the network formation. A proteomic analysis indicated that FSK elevated the levels of regulators of the cytoskeleton, among others (data available via ProteomeXchange with identifier PXD032160). The steroidogenic enzyme CYP11A1 (Cytochrome P450 Family 11 Subfamily A Member 1), located in mitochondria, was more than 3-fold increased by FSK, implying that the cAMP/PKA-associated structural changes occur in parallel with the acquisition of steroidogenic competence of mitochondria in KGN cells. In summary, the observations show increases in mitochondria and suggest intracellular trafficking of mitochondria in GCs during follicular growth, and indicate that they may partially be under the control of gonadotropins and cAMP. In line with this, increased cAMP in KGN cells profoundly affected mitochondrial dynamics in a PKA-dependent manner and implicated cytoskeletal changes.

Mitochondrial Genome Contributes to the Thermal Adaptation of the Oomycete Phytophthora infestans

As a vital element of climate change, elevated temperatures resulting from global warming present new challenges to natural and agricultural sustainability, such as ecological disease management. Mitochondria regulate the energy production of cells in responding to environmental fluctuation, but studying their contribution to the thermal adaptation of species is limited. This knowledge is needed to predict future disease epidemiology for ecology conservation and food security. Spatial distributions of the mitochondrial genome (mtDNA) in 405 Phytophthora infestans isolates originating from 15 locations were characterized. The contribution of MtDNA to thermal adaptation was evaluated by comparative analysis of mtDNA frequency and intrinsic growth rate, relative population differentiation in nuclear and mtDNA, and associations of mtDNA distribution with local geography climate conditions. Significant variation in frequency, intrinsic growth rate, and spatial distribution was detected in mtDNA. Population differentiation in mtDNA was significantly higher than that in the nuclear genome, and spatial distribution of mtDNA was strongly associated with local climatic conditions and geographic parameters, particularly air temperature, suggesting natural selection caused by a local temperature is the main driver of the adaptation. Dominant mtDNA grew faster than the less frequent mtDNA. Our results provide useful insights into the evolution of pathogens under global warming. Given its important role in biological functions and adaptation to local air temperature, mtDNA intervention has become an increasing necessity for future disease management. To secure ecological integrity and food production under global warming, a synergistic study on the interactive effect of changing temperature on various components of biological and ecological functions of mitochondria in an evolutionary frame is urgently needed.

Thymoquinone Alterations of the Apoptotic Gene Expressions and Cell Cycle Arrest in Genetically Distinct Triple-Negative Breast Cancer Cells

Breast cancer (BC) is the most common cancer in women worldwide, and it is one of the leading causes of cancer death in women. triple-negative breast Cancer (TNBC), a subtype of BC, is typically associated with the highest pathogenic grade and incidence in premenopausal and young African American (AA) women. Chemotherapy, the most common treatment for TNBC today, can lead to acquired resistance and ineffective treatment. Therefore, novel therapeutic approaches are needed to combat medication resistance and ineffectiveness in TNBC patients. Thymoquinone (TQ) is shown to have a cytotoxic effect on human cancer cells in vitro. However, TQ's mode of action and precise mechanism in TNBC disease in vitro have not been adequately investigated. Therefore, TQ's effects on the genetically different MDA-MB-468 and MDA-MB-231 human breast cancer cell lines were assessed. The data obtained show that TQ displayed cytotoxic effects on MDA-MB-468 and MDA-MB-231 cells in a time- and concentration-dependent manner after 24 h, with IC50 values of 25.37 µM and 27.39 µM, respectively. Moreover, MDA-MB-231 and MDA-MB-468 cells in a scratched wound-healing assay displayed poor wound closure, inhibiting invasion and migration via cell cycle blocking after 24 h. TQ arrested the cell cycle phase in MDA-MB-231 and MDA-MB-468 cells. The three cell cycle stages in MDA-MB-468 cells were significantly affected at 15 and 20 µM for G0/G1 and S phases, as well as all TQ concentrations for G2/M phases. In MDA-MB-468 cells, there was a significant decrease in G0/G1 phases with a substantial increase in the S phase and G2/M phases. In contrast, MDA-MB-231 showed a significant effect only during the two cell cycle stages (S and G2/M), at concentrations of 15 and 20 µM for S phases and all TQ values for G2/M phases. The TQ effect on the apoptotic gene profiles indicated that TQ upregulated 15 apoptotic genes in MDA-MB-231 TNBC cells, including caspases, GADD45A, TP53, DFFA, DIABLO, BNIP3, TRAF2/3, and TNFRSF10A. In MDA-MB-468 cells, 16 apoptotic genes were upregulated, including TNFRSF10A, TNF, TNFRSF11B, FADD TNFRSF10B, CASP2, and TRAF2, all of which are important for the apoptotic pathway andsuppress the expression of one anti-apoptotic gene, BIRC5, in MDA-MB-231 cells. Compared to MDA-MB-231 cells, elevated levels of TNF and their receptor proteins may contribute to their increased sensitivity to TQ-induced apoptosis. It was concluded from this study that TQ targets the MDA-MB-231 and MDA-MB-468 cells differently. Additionally, due to the aggressive nature of TNBC and the lack of specific therapies in chemoresistant TNBC, our findings related to the identified apoptotic gene profile may point to TQ as a potential agent for TNBC therapy.

The Interplay of Microtubules with Mitochondria–ER Contact Sites (MERCs) in Glioblastoma

Gliomas are heterogeneous neoplasms, classified into grade I to IV according to their malignancy and the presence of specific histological/molecular hallmarks. The higher grade of glioma is known as glioblastoma (GB). Although progress has been made in surgical and radiation treatments, its clinical outcome is still unfavorable. The invasive properties of GB cells and glioma aggressiveness are linked to the reshaping of the cytoskeleton. Recent works suggest that the different susceptibility of GB cells to antitumor immune response is also associated with the extent and function of mitochondria–ER contact sites (MERCs). The presence of MERCs alterations could also explain the mitochondrial defects observed in GB models, including abnormalities of energy metabolism and disruption of apoptotic and calcium signaling. Based on this evidence, the question arises as to whether a MERCs–cytoskeleton crosstalk exists, and whether GB progression is linked to an altered cytoskeleton–MERCs interaction. To address this possibility, in this review we performed a meta-analysis to compare grade I and grade IV GB patients. From this preliminary analysis, we found that GB samples (grade IV) are characterized by altered expression of cytoskeletal and MERCs related genes. Among them, the cytoskeleton-associated protein 4 (CKAP4 or CLIMP-63) appears particularly interesting as it encodes a MERCs protein controlling the ER anchoring to microtubules (MTs). Although further in-depth analyses remain necessary, this perspective review may provide new hints to better understand GB molecular etiopathogenesis, by suggesting that cytoskeletal and MERCs alterations cooperate to exacerbate the cellular phenotype of high-grade GB and that MERCs players can be exploited as novel biomarkers/targets to enhance the current therapy for GB.