Inflammation-induced PINCH expression leads to actin depolymerization and mitochondrial mislocalization in neurons

Regulation of mitochondrial structure by the actin cytoskeleton

Mitochondria are the powerhouse of the cell and play important roles in multiple cellular processes including cell metabolism, proliferation, and programmed cell death. Mitochondria are double-membrane organelles with the inner membrane folding inward to form cristae. Mitochondria networks undergo dynamic fission and fusion. Deregulation of mitochondrial structure has been linked to perturbed mitochondrial membrane potential and disrupted metabolism, as evidenced in tumorigenesis, neurodegenerative diseases, etc. Actin and its motors-myosins have long been known to generate mechanical forces and participate in short-distance cargo transport. Accumulating knowledge from biochemistry and live cell/electron microscope imaging has demonstrated the role of actin filaments in pre-constricting the mitochondria during fission. Recent studies have suggested the involvement of myosins in cristae maintenance and mitochondria quality control. Here, we review current findings and discuss future directions in the emerging fields of cytoskeletal regulation in cristae formation, mitochondrial dynamics, intracellular transport, and mitocytosis, with focus on the actin cytoskeleton and its motor proteins.

HSF4/COIL complex-dependent R-loop mediates ultraviolet-induced inflammatory skin injury

Intense ultraviolet (UV) exposure can cause phototoxic reactions, such as skin inflammation, resulting in injury. UV is a direct cause of DNA damage, but the mechanisms underlying transcriptional regulation within cells after DNA damage are unclear. The bioinformatics analysis of transcriptome sequencing data from UV-irradiated and non-UV-irradiated skin showed that transcription-related proteins, such as HSF4 and COIL, mediate cellular response to UV irradiation. HSF4 and COIL can form a complex under UV irradiation, and the preference for binding target genes changed because of the presence of a large number of R-loops in cells under UV irradiation and the ability of COIL to recognize R-loops. The regulation of target genes was altered by the HSF4-COIL complex, and the expression of inflammation and ageing-related genes, such as Atg7, Tfpi, and Lims1, was enhanced. A drug screen was performed for the recognition sites of COIL and R-loop. N6-(2-hydroxyethyl)-adenosine can competitively bind COIL and inhibit the binding of COIL to the R-loop. Thus, the activation of downstream inflammation-related genes and inflammatory skin injury was inhibited.

The Role of MEF2 Transcription Factor Family in Neuronal Survival and Degeneration

The family of myocyte enhancer factor 2 (MEF2) transcription factors comprises four highly conserved members that play an important role in the nervous system. They appear in precisely defined time frames in the developing brain to turn on and turn off genes affecting growth, pruning and survival of neurons. MEF2s are known to dictate neuronal development, synaptic plasticity and restrict the number of synapses in the hippocampus, thus affecting learning and memory formation. In primary neurons, negative regulation of MEF2 activity by external stimuli or stress conditions is known to induce apoptosis, albeit the pro or antiapoptotic action of MEF2 depends on the neuronal maturation stage. By contrast, enhancement of MEF2 transcriptional activity protects neurons from apoptotic death both in vitro and in preclinical models of neurodegenerative diseases. A growing body of evidence places this transcription factor in the center of many neuropathologies associated with age-dependent neuronal dysfunctions or gradual but irreversible neuron loss. In this work, we discuss how the altered function of MEF2s during development and in adulthood affecting neuronal survival may be linked to neuropsychiatric disorders.

The role of Actopaxin in tumor metastasis

Actopaxin is a newly discovered focal adhesions (FAs) protein, actin-binding protein and pseudopodia-enriched molecule. It can not only bind to a variety of FAs proteins (such as Paxillin, ILK and PINCH) and non-FAs proteins (such as TESK1, CdGAP, β2-adaptin, G3BP2, ADAR1 and CD29), but also participates in multiple signaling pathways. Thus, it plays a crucial role in regulating important processes of tumor metastasis, including matrix degradation, migration, and invasion, etc. This review covers the latest progress in the structure and function of Actopaxin, its interaction with other proteins as well as its involvement in regulating tumor development and metastasis. Additionally, the current limitations for Actopaxin related studies and the possible research directions on it in the future are also discussed. It is hoped that this review can assist relevant researchers to obtain a deep understanding of the role that Actopaxin plays in tumor progression, and also enlighten further research and development of therapeutic approaches for the treatment of tumor metastasis.

Changes of Gene Expression Patterns of Muscle Pathophysiology-Related Transcription Factors During Denervated Muscle Atrophy

Peripheral nerve injury is common, and can lead to skeletal muscle atrophy and dysfunction. However, the underlying molecular mechanisms are not fully understood. The transcription factors have been proved to play a key role in denervated muscle atrophy. In order to systematically analyze transcription factors and obtain more comprehensive information of the molecular regulatory mechanisms in denervated muscle atrophy, a new transcriptome survey focused on transcription factors are warranted. In the current study, we used microarray to identify and analyze differentially expressed genes encoding transcription factors in denervated muscle atrophy in a rat model of sciatic nerve dissection. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were used to explore the biological functions of differentially expressed transcription factors and their target genes related to skeletal muscle pathophysiology. We found that the differentially expressed transcription factors were mainly involved in the immune response. Based on correlation analysis and the expression trends of transcription factors, 18 differentially expressed transcription factors were identified. Stat3, Myod1, Runx1, Atf3, Junb, Runx2, Myf6, Stat5a, Tead4, Klf5, Myog, Mef2a, and Hes6 were upregulated. Ppargc1a, Nr4a1, Lhx2, Ppara, and Rxrg were downregulated. Functional network mapping revealed that these transcription factors are mainly involved in inflammation, development, aging, proteolysis, differentiation, regeneration, autophagy, oxidative stress, atrophy, and ubiquitination. These findings may help understand the regulatory mechanisms of denervated muscle atrophy and provide potential targets for future therapeutic interventions for muscle atrophy following peripheral nerve injury.

The Interplay between Cell-Extracellular Matrix Interaction and Mitochondria Dynamics in Cancer

The tumor microenvironment, in particular the extracellular matrix (ECM), plays a pivotal role in controlling tumor initiation and progression. In particular, the interaction between cancer cells and the ECM promotes cancer cell growth and invasion, leading to the formation of distant metastasis. Alterations in cancer cell metabolism is a key hallmark of cancer, which is often associated with alterations in mitochondrial dynamics. Recent research highlighted that, changes in mitochondrial dynamics are associated with cancer migration and metastasis-these has been extensively reviewed elsewhere. However, less is known about the interplay between the extracellular matrix and mitochondria functions. In this review, we will highlight how ECM remodeling associated with tumorigenesis contribute to the regulation of mitochondrial function, ultimately promoting cancer cell metabolic plasticity, able to fuel cancer invasion and metastasis.

How signaling pathways link extracellular mechano-environment to proline biosynthesis: A hypothesis: PINCH-1 and kindlin-2 sense mechanical signals from extracellular matrix and link them to proline biosynthesis

We propose a signaling pathway in which cell-extracellular matrix (ECM) adhesion components PINCH-1 and kindlin-2 sense mechanical signals from ECM and link them to proline biosynthesis, a vital metabolic pathway for macromolecule synthesis, redox balance, and ECM remodeling. ECM stiffening promotes PINCH-1 expression via integrin signaling, which suppresses dynamin-related protein 1 (DRP1) expression and mitochondrial fission, resulting in increased kindlin-2 translocation into mitochondria and interaction with Δ¹ -pyrroline-5-carboxylate (P5C) reductase 1 (PYCR1). Kindlin-2 interaction with PYCR1 protects the latter from proteolytic degradation, leading to elevated PYCR1 level. Additionally, PINCH-1 promotes P5C synthase (P5CS) expression and P5C synthesis, which, together with increased PYCR1 level, support augmented proline biosynthesis. This signaling pathway is frequently activated in fibrosis and cancer, resulting in increased proline biosynthesis and excessive collagen matrix production, which in turn further promotes ECM stiffening. Targeting this signaling pathway, therefore, may provide an effective strategy for alleviating fibrosis and cancer progression.

N-retinylidene-N-retinylethanolamine adduct induces expression of chronic inflammation cytokines in retinal pigment epithelium cells

Blindness due to photoreceptor degeneration is observed in both genetic and acquired eye disorders. Long blue light exposure can contribute to increase levels of oxidative compounds within the retinal pigment epithelium (RPE), enhancing risk of retinal damage. In retina, reactive oxygen species contribute to the activation of inflammatory cascade. If chronic, this inflammatory response can result in photoreceptor death. Therefore, we investigated the effects of the endogenous adduct N-retinylidene-N-retinylethanolamine (A2E) on RPE cells, in order to identify the most dysregulated cytokines and their related inflammatory pathways. RPE cells were exposed to A2E and blue light for 3h and 6h. By transcriptome analysis, we identified differentially expressed genes in A2E-treated cells, when compared to untreated ones. Expression values were quantified by the Limma R package. Enrichment analysis was performed according to the "Reactome" and the Gene Ontology databases. Expression of pro-inflammatory cytokines increased after 3h of A2E treatment and pathways related to IL-6 and IL-1 signaling resulted enriched. Also the up-regulation of genes having a protective role against inflammation was observed. Moreover, our results show that ferroptosis could contribute to RPE degeneration induced by A2E and blue light. Dysregulated genes related to retinal degeneration triggered by oxidative damage and inflammatory response activation identified in this study can be considered as potential biomarkers for targeted therapies.

The emerging potential of SIRT-3 in oxidative stress-inflammatory axis associated increased neuroinflammatory component for metabolically impaired neural cell

People suffering from conditions like epilepsy, where there is an excess of neuron excitement, stroke, and cardiac arrest, where there are oxygen and glucose deprivation, Alzheimer, Parkinson, and Huntington's disease that causes metabolic and also oxidative stress-inflammatory axis; are known to be more vulnerable to disturbances in the metabolism, and there is a lot of inadequacy in defining the inflammation's mechanistic connections, as well as neurodegeneration and the bioenergetic deficiencies in the CNS. We retrieved relevant studies from PubMed/ScienceDirect/Medline/Public library of science/Mendeley/Springer link as well as Google Scholar. We used various keywords both individually and in combination with the literature search. 'Epidemiology of neurodegenerative disorders', 'neurodegenerative diseases associated hyper inflammation', 'Mechanism of inflammation in neuronal cell', 'Involvement of SIRTin inflammation', 'Pathogenesis of mitochondrial associated metabolic impairment in neurons', 'Reactive oxygen species-mediated mitochondrial dysfunction' were a few of the keywords used for the search. PINCH, which is a chronic neuro-inflammatory component that cannot be detected in matured neurons which are healthy, though expressed in oxidative stress inflammatory axis related tauopathy and diseases that cause neurodegeneration. We attempted to study the regulatory mechanisms that cause changes in the bioenergetics and its neuronal defects and mitochondrial subcellular localization that are PINCH protein-mediated on the other handSIRT1, the most intensively studied sirtuin, in oxidative stress-mediated inflammatory consequence for many diseases but very few research data explore the role of SIRT-3 for correction of the chronic neuroinflammatory component. Thus, in this review, we investigate the very recently identified molecules involving in the pathogenesis during stimulated oxidative stress-inflammatory axis in the excitatory neuronal cell which changes brain metabolism. Simultaneously, in CNS neurons of diseases with a component of chronic neuroinflammation which exhibit neuroprotective response, the consequences (mechanistic and biological) of SIRT-3, could be emerging future targets for neurodegenerative disorder treatment with impaired metabolisms.