Crosstalk between Rac1-mediated actin regulation and ROS production

PlexinA1 promotes gastric cancer migration through preventing MICAL1 protein ubiquitin/proteasome-mediated degradation in a Rac1-dependent manner

Metastasis promotes the development of tumors and is a significant cause of gastric cancer death. For metastasis to proceed, tumor cells must become mobile by modulating their cytoskeleton. MICAL1 (Molecule Interacting with CasL1) is known as an actin cytoskeleton regulator, but the mechanisms by which it drives gastric cancer cell migration are still unclear. Analysis of gastric cancer tissues revealed that MICAL1 expression is dramatically upregulated in stomach adenocarcinoma (STAD) samples as compared to noncancerous stomach tissues. Patients with high MICAL1 expression had shorter overall survival (OS), post-progression survival (PPS) and first-progression survival (FPS) compared with patients with low MICAL1 expression. RNAi-mediated silencing of MICAL1 inhibited the expression of Vimentin, a protein involved in epithelial-mesenchymal transition. This effect correlates with a significant reduction in gastric cancer cell migration. MICAL1 overexpression reversed these preventive effects. Immunoprecipitation experiments and immunofluorescence assays revealed that PlexinA1 forms a complex with MICAL1. Importantly, specific inhibition of PlexinA1 blocked the Rac1 activation and ROS production, which, in turn, impaired MICAL1 protein stability by accelerating MICAL1 ubiquitin/proteasome-dependent degradation. Overexpression of PlexinA1 enhanced Rac1 activation, ROS production, MICAL1 and Vimentin expressions, and favored cell migration. In conclusion, this study identified MICAL1 as an important facilitator of gastric cancer cell migration, at least in part, by affecting Vimentin expression and PlexinA1 promotes gastric cancer cell migration by binding to and suppressing MICAL1 degradation in a Rac1/ROS-dependent manner.

The NADPH oxidase 2 subunit p47phox binds to the WAVE regulatory complex and p22phox in a mutually exclusive manner

The actin cytoskeleton and reactive oxygen species (ROS) both play crucial roles in various cellular processes. Previous research indicated a direct interaction between two key components of these systems: the WAVE1 subunit of the WAVE regulatory complex (WRC), which promotes actin polymerization and the p47phox subunit of the NADPH oxidase 2 complex (NOX2), which produces ROS. Here, using carefully characterized recombinant proteins, we find that activated p47phox uses its dual Src homology 3 domains to bind to multiple regions within the WAVE1 and Abi2 subunits of the WRC, without altering WRC's activity in promoting Arp2/3-mediated actin polymerization. Notably, contrary to previous findings, p47phox uses the same binding pocket to interact with both the WRC and the p22phox subunit of NOX2, albeit in a mutually exclusive manner. This observation suggests that when activated, p47phox may separately participate in two distinct processes: assembling into NOX2 to promote ROS production and engaging with WRC to regulate the actin cytoskeleton.

Identification and analysis of the molecular targets of statins in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer in the world. According to several types of research, statins may impact the development and treatment of CRC. This work aimed to use bioinformatics to discover the relationship between statin targets and differentially expressed genes (DEGs) in CRC patients and determine the possible molecular effect of statins on CRC suppression. We used CRC datasets from the GEO database to select CRC-related DEGs. DGIdb and STITCH databases were used to identify gene targets of subtypes of statin. Further, we identified the statin target of CRC DEGs hub genes by using a Venn diagram of CRC DEGs and statin targets. Funrich and enrichr databases were carried out for the KEGG pathway and gene ontology (GO) enrichment analysis, respectively. GSE74604 and GSE10950 were used to identify CRC DEGs. After analyzing datasets,1370 genes were identified as CRC DEGs, and 345 targets were found for statins. We found that 35 genes are CRC DEGs statin targets. We found that statin targets in CRC were enriched in the receptor and metallopeptidase activity for molecular function, cytoplasm and plasma membrane for cellular component, signal transduction, and cell communication for biological process genes were substantially enriched based on FunRich enrichment. Analysis of the KEGG pathways revealed that the overexpressed DEGs were enriched in the IL-17, PPAR, and Toll-like receptor signaling pathways. Finally, CCNB1, DNMT1, AURKB, RAC1, PPARGC1A, CDKN1A, CAV1, IL1B, and HSPD1 were identified as hub CRC DEGs statin targets. The genetic and molecular aspects of our findings reveal that statins might have a therapeutic effect on CRC.

Functional Conservation of the Small GTPase Rho5/Rac1-A Tale of Yeast and Men

Small GTPases are molecular switches that participate in many essential cellular processes. Amongst them, human Rac1 was first described for its role in regulating actin cytoskeleton dynamics and cell migration, with a close relation to carcinogenesis. More recently, the role of Rac1 in regulating the production of reactive oxygen species (ROS), both as a subunit of NADPH oxidase complexes and through its association with mitochondrial functions, has drawn attention. Malfunctions in this context affect cellular plasticity and apoptosis, related to neurodegenerative diseases and diabetes. Some of these features of Rac1 are conserved in its yeast homologue Rho5. Here, we review the structural and functional similarities and differences between these two evolutionary distant proteins and propose yeast as a useful model and a device for high-throughput screens for specific drugs.

Divergent iron-regulatory states contribute to heterogeneity in breast cancer aggressiveness

Primary tumors with similar mutational profiles can progress to vastly different outcomes where transcriptional state, rather than mutational profile, predicts prognosis. A key challenge is to understand how distinct tumor cell states are induced and maintained. In triple negative breast cancer cells, invasive behaviors and aggressive transcriptional signatures linked to poor patient prognosis can emerge in response to contact with collagen type I. Herein, collagen-induced migration heterogeneity within a TNBC cell line was leveraged to identify transcriptional programs associated with invasive versus non-invasive phenotypes and implicate molecular switches. Phenotype-guided sequencing revealed that invasive cells upregulate iron uptake and utilization machinery, anapleurotic TCA cycle genes, actin polymerization promoters, and a distinct signature of Rho GTPase activity and contractility regulating genes. The non-invasive cell state is characterized by actin and iron sequestration modules along with glycolysis gene expression. These unique tumor cell states are evident in patient tumors and predict divergent outcomes for TNBC patients. Glucose tracing confirmed that non-invasive cells are more glycolytic than invasive cells, and functional studies in cell lines and PDO models demonstrated a causal relationship between phenotype and metabolic state. Mechanistically, the OXPHOS dependent invasive state resulted from transient HO-1 upregulation triggered by contact with dense collagen that reduced heme levels and mitochondrial chelatable iron levels. This induced expression of low cytoplasmic iron response genes regulated by ACO1/IRP1. Knockdown or inhibition of HO-1, ACO1/IRP1, MRCK, or OXPHOS abrogated invasion. These findings support an emerging theory that heme and iron flux serve as important regulators of TNBC aggressiveness.

ROCK inhibition reduces the sensitivity of mutant p53 glioblastoma to genotoxic stress through a Rac1-driven ROS production

Resistance to radio and chemotherapy in Glioblastoma (GBM) is correlated with its malignancy, invasiveness, and aggressiveness. The Rho GTPase pathway plays important roles in these processes, but its involvement in the GBM response to genotoxic treatments remains unsolved. Inhibition of this signaling pathway has emerged as a promising approach for the treatment of CNS injuries and diseases, proving to be a strong candidate for therapeutic approaches. To this end, Rho-associated kinases (ROCK), classic downstream effectors of small Rho GTPases, were targeted for pharmacological inhibition using Y-27632 in GBM cells, expressing the wild-type or mutated p53 gene, and exposed to genotoxic stress by gamma ionizing radiation (IR) or cisplatin (PT). The use of the ROCK inhibitor (ROCKi) had opposite effects in these cells: in cells expressing wild-type p53, ROCKi reduced survival and DNA repair capacity (reduction of γH2AX foci and accumulation of strand breaks) after stress promoted by IR or PT; in cells expressing the mutant p53 protein, both treatments promoted longer survival and more efficient DNA repair, responses further enhanced by ROCKi. The target DNA repair mechanisms of ROCK inhibition were, respectively, an attenuation of NHEJ and NER pathways in wild-type p53 cells, and a stimulation of HR and NER pathways in mutant p53 cells. These effects were accompanied by the formation of reactive oxygen species (ROS) induced by genotoxic stress only in mutant p53 cells but potentiated by ROCKi and reversed by p53 knockdown. N-acetyl-L-cysteine (NAC) treatment or Rac1 knockdown completely eliminated ROCKi's p53-dependent actions, since ROCK inhibition specifically elevated Rac-GTP levels only in mutant p53 cells. Combining IR or PT and ROCKi treatments broadens our understanding of the sensitivity and resistance of, respectively, GBM expressing wild-type or mutant p53 to genotoxic agents. Our proposal may be a determining factor in improving the efficiency and assertiveness of CNS antitumor therapies based on ROCK inhibitors. SIGNIFICANCE: The use of ROCK inhibitors in association with radio or chemotherapy modulates GBM resistance and sensitivity depending on the p53 activity, suggesting the potential value of this protein as therapeutic target for tumor pre-sensitization strategies.

Molecular mechanisms of endothelial dysfunction in coronary microcirculation dysfunction

Coronary microvascular endothelial cells (CMECs) react to changes in coronary blood flow and myocardial metabolites and regulate coronary blood flow by balancing vasoconstrictors-such as endothelin-1-and the vessel dilators prostaglandin, nitric oxide, and endothelium-dependent hyperpolarizing factor. Coronary microvascular endothelial cell dysfunction is caused by several cardiovascular risk factors and chronic rheumatic diseases that impact CMEC blood flow regulation, resulting in coronary microcirculation dysfunction (CMD). The mechanisms of CMEC dysfunction are not fully understood. However, the following could be important mechanisms: the overexpression and activation of nicotinamide adenine dinucleotide phosphate oxidase (Nox), and mineralocorticoid receptors; the involvement of reactive oxygen species (ROS) caused by a decreased expression of sirtuins (SIRT3/SIRT1); forkhead box O3; and a decreased SKCA/IKCA expression in the endothelium-dependent hyperpolarizing factor electrical signal pathway. In addition, p66Shc is an adapter protein that promotes oxidative stress; although there are no studies on its involvement with cardiac microvessels, it is possible it plays an important role in CMD.

Secreted endogenous macrosomes reduce Aβ burden and ameliorate Alzheimer's disease

Innovative therapeutic strategies are urgently needed for Alzheimer's disease (AD) due to the increasing size of the aging population and the lack of effective drug treatment. Here, we report the therapeutic effects of extracellular vesicles (EVs) secreted by microglia, including macrosomes and small EVs, on AD-associated pathology. Macrosomes strongly inhibited β-amyloid (Aβ) aggregation and rescued cells from Aβ misfolding-induced cytotoxicity. Furthermore, macrosome administration reduced Aβ plaques and ameliorated cognitive impairment in mice with AD. In contrast, small EVs slightly promoted Aβ aggregation and did not improve AD pathology. Proteomic analysis of small EVs and macrosomes revealed that macrosomes harbor several important neuroprotective proteins that inhibit Aβ misfolding. In particular, the small integral membrane protein 10-like protein 2B in macrosomes has been shown to inhibit Aβ aggregation. Our observations provide an alternative therapeutic strategy for the treatment of AD over conventional ineffective drug treatments.

The role of wnt signaling in diabetes-induced osteoporosis

Osteoporosis, a chronic complication of diabetes mellitus, is characterized by a reduction in bone mass, destruction of bone microarchitecture, decreased bone strength, and increased bone fragility. Because of its insidious onset, osteoporosis renders patients highly susceptible to pathological fractures, leading to increased disability and mortality rates. However, the specific pathogenesis of osteoporosis induced by chronic hyperglycemia has not yet been fully elucidated. But it is currently known that the disruption of Wnt signaling triggered by chronic hyperglycemia is involved in the pathogenesis of diabetic osteoporosis. There are two main types of Wnt signaling pathways, the canonical Wnt signaling pathway (β-catenin-dependent) and the non-canonical Wnt signaling pathway (non-β-catenin-dependent), both of which play an important role in regulating the balance between bone formation and bone resorption. Therefore, this review systematically describes the effects of abnormal Wnt pathway signaling on bone homeostasis under hyperglycemia, hoping to reveal the relationship between Wnt signaling and diabetic osteoporosis to further improve understanding of this disease.

Berberine hydrochloride inhibits migration ability via increasing inducible NO synthase and peroxynitrite in HTR-8/SVneo cells

ETHNOPHARMACOLOGICAL RELEVANCE

Inadequate trophoblasts migration and invasion is considered as an initial event resulting in preeclampsia, which is closely related to oxidative stress. Berberine hydrochloride (BBR), extracted from the traditional medicinal plant Coptis chinensis Franch., exerts a diversity of pharmacological effects, and the crude drug has been widely taken by most Chinese women to treat nausea and vomit during pregnancy. But there is no research regarding its effects on trophoblast cell function.

AIM OF THE STUDY

This study aimed to investigate the effect of BBR on human-trophoblast-derived cell line (HTR-8/SVneo) migration ability and its mechanism.

MATERIALS AND METHODS

Cell viability was detected by CCK-8 assay. The effect of BBR on cells migration function was examined by scratch wound healing assay and transwell migration assay. Intracellular nitric oxide (NO), superoxide (O₂^-) and peroxynitrite (ONOO^-) levels were measured by flow cytometry. The expression levels of inducible NO synthase (iNOS), eNOS, p-eNOS, MnSOD, CuZnSOD, Rac1, NOX1, TLR4, nuclear factor-κB (NF-κB), p-NFκB, pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) in cells were analyzed by Western blotting. Uric acid sodium salt (UA), the scavenger of ONOO^-, PEG-SOD (a specific superoxide scavenger), L-NAME (a NOS inhibitor) and antioxidants (Vit E and DFO) were further used to characterize the pathway of BBR action.

RESULTS

5 μM BBR decreased both the migration distance and the number of migrated cells without affecting cells viability in HTR-8/SVneo cells after 24 h treatment. BBR could increase the level of NO in HTR-8/SVneo cells, and the over-production of NO might be attributable to iNOS, but not eNOS. BBR could increase intracellular O₂^- levels, and the over-production of O₂^- is closely related with Rac1 in HTR-8/SVneo cells. The excessive production of NO and O₂^- further react to form ONOO^-, and the increased ONOO^- level induced by BBR was blunted by UA. Moreover, UA improved the impaired migration function caused by BBR in HTR-8/SVneo cells. The depressed migration function stimulated by BBR in HTR-8/SVneo cells was diminished by PEG-SOD and L-NAME. Furthermore, BBR increased the expression of IL-6 in HTR-8/SVneo cells, and antioxidants (Vit E and DFO) could decrease the expression of IL-6 and iNOS induced by BBR.

CONCLUSIONS

BBR inhibits the cell migration ability through increasing inducible NO synthase and peroxynitrite in HTR-8/SVneo cells, indicating that BBR and traditional Chinese medicines containing a high proportion of BBR should be used with caution in pregnant women.

A Role for Second Messengers in Axodendritic Neuronal Polarity

Neuronal polarization is a complex molecular process regulated by intrinsic and extrinsic mechanisms. Nerve cells integrate multiple extracellular cues to generate intracellular messengers that ultimately control cell morphology, metabolism, and gene expression. Therefore, second messengers' local concentration and temporal regulation are crucial elements for acquiring a polarized morphology in neurons. This review article summarizes the main findings and current understanding of how Ca2+, IP3, cAMP, cGMP, and hydrogen peroxide control different aspects of neuronal polarization, and highlights questions that still need to be resolved to fully understand the fascinating cellular processes involved in axodendritic polarization.

Study of the shared gene signatures of polyarticular juvenile idiopathic arthritis and autoimmune uveitis

Objective

To explore the shared gene signatures and potential molecular mechanisms of polyarticular juvenile idiopathic arthritis (pJIA) and autoimmune uveitis (AU).

Method

The microarray data of pJIA and AU from the Gene Expression Omnibus (GEO) database were downloaded and analyzed. The GEO2R tool was used to identify the shared differentially expressed genes (DEGs) and genes of extracellular proteins were identified among them. Then, weighted gene co-expression network analysis (WGCNA) was used to identify the shared immune-related genes (IRGs) related to pJIA and AU. Moreover, the shared transcription factors (TFs) and microRNAs (miRNAs) in pJIA and AU were acquired by comparing data from HumanTFDB, hTFtarget, GTRD, HMDD, and miRTarBase. Finally, Metascape and g: Profiler were used to carry out function enrichment analyses of previously identified gene sets.

Results

We found 40 up-regulated and 15 down-regulated shared DEGs via GEO2R. Then 24 shared IRGs in positivity-related modules, and 18 shared IRGs in negatively-related modules were found after WGCNA. After that, 3 shared TFs (ARID1A, SMARCC2, SON) were screened. And the constructed TFs-shared DEGs network indicates a central role of ARID1A. Furthermore, hsa-miR-146 was found important in both diseases. The gene sets enrichment analyses suggested up-regulated shared DEGs, TFs targeted shared DEGs, and IRGs positivity-correlated with both diseases mainly enriched in neutrophil degranulation process, IL-4, IL-13, and cytokine signaling pathways. The IRGs negatively correlated with pJIA and AU mainly influence functions of the natural killer cell, cytotoxicity, and glomerular mesangial cell proliferation. The down-regulated shared DEGs and TFs targeted shared DEGs did not show particular functional enrichment.

Conclusion

Our study fully demonstrated the flexibility and complexity of the immune system disorders involved in pJIA and AU. Neutrophil degranulation may be considered the shared pathogenic mechanism, and the roles of ARID1A and MiR-146a are worthy of further in-depth study. Other than that, the importance of periodic inspection of kidney function is also noteworthy.

The pseudokinase NRBP1 activates Rac1/Cdc42 via P-Rex1 to drive oncogenic signalling in triple-negative breast cancer

We have determined that expression of the pseudokinase NRBP1 positively associates with poor prognosis in triple negative breast cancer (TNBC) and is required for efficient migration, invasion and proliferation of TNBC cells in culture as well as growth of TNBC orthotopic xenografts and experimental metastasis. Application of BioID/MS profiling identified P-Rex1, a known guanine nucleotide exchange factor for Rac1, as a NRBP1 binding partner. Importantly, NRBP1 overexpression enhanced levels of GTP-bound Rac1 and Cdc42 in a P-Rex1-dependent manner, while NRBP1 knockdown reduced their activation. In addition, NRBP1 associated with P-Rex1, Rac1 and Cdc42, suggesting a scaffolding function for this pseudokinase. NRBP1-mediated promotion of cell migration and invasion was P-Rex1-dependent, while constitutively-active Rac1 rescued the effect of NRBP1 knockdown on cell proliferation and invasion. Generation of reactive oxygen species via a NRBP1/P-Rex1 pathway was implicated in these oncogenic roles of NRBP1. Overall, these findings define a new function for NRBP1 and a novel oncogenic signalling pathway in TNBC that may be amenable to therapeutic intervention.

Calpain Regulates Reactive Oxygen Species Production during Capacitation through the Activation of NOX2 and NOX4

Capacitation is a series of physiological, biochemical, and metabolic changes experienced by mammalian spermatozoa. These changes enable them to fertilize eggs. The capacitation prepares the spermatozoa to undergo the acrosomal reaction and hyperactivated motility. Several mechanisms that regulate capacitation are known, although they have not been fully disclosed; among them, reactive oxygen species (ROS) play an essential role in the normal development of capacitation. NADPH oxidases (NOXs) are a family of enzymes responsible for ROS production. Although their presence in mammalian sperm is known, little is known about their participation in sperm physiology. This work aimed to identify the NOXs related to the production of ROS in guinea pig and mouse spermatozoa and define their participation in capacitation, acrosomal reaction, and motility. Additionally, a mechanism for NOXs' activation during capacitation was established. The results show that guinea pig and mouse spermatozoa express NOX2 and NOX4, which initiate ROS production during capacitation. NOXs inhibition by VAS2870 led to an early increase in the capacitation and intracellular concentration of Ca²⁺ in such a way that the spermatozoa also presented an early acrosome reaction. In addition, the inhibition of NOX2 and NOX4 reduced progressive motility and hyperactive motility. NOX2 and NOX4 were found to interact with each other prior to capacitation. This interaction was interrupted during capacitation and correlated with the increase in ROS. Interestingly, the association between NOX2-NOX4 and their activation depends on calpain activation, since the inhibition of this Ca²⁺-dependent protease prevents NOX2-NOX4 from dissociating and ROS production. The results indicate that NOX2 and NOX4 could be the most important ROS producers during guinea pig and mouse sperm capacitation and that their activation depends on calpain.

ARHGAP15 promotes metastatic colonization in gastric cancer by suppressing RAC1-ROS pathway

The molecular mechanism of tumor metastasis, especially how metastatic tumor cells colonize in a distant site, remains poorly understood. Here we reported that ARHGAP15, a Rho GTPase activating protein, enhanced gastric cancer (GC) metastatic colonization, which was quite different from its reported role as a tumor suppressor gene in other cancers. It was upregulated in metastatic lymph nodes and significantly associated with a poor prognosis. Ectopic expression of ARHGAP15 promoted metastatic colonization of gastric cancer cells in murine lungs and lymph nodes in vivo or protected cells from oxidative-related death in vitro. However, genetic downregulation of ARHGAP15 had the opposite effect. Mechanistically, ARHGAP15 inactivated RAC1 and then decreased intracellular accumulation of reactive oxygen species (ROS), thus enhancing the antioxidant capacity of colonizing tumor cells under oxidative stress. This phenotype could be phenocopied by inhibition of RAC1 or rescued by the introduction of constitutively active RAC1 into cells. Taken together, these findings suggested a novel role of ARHGAP15 in promoting gastric cancer metastasis by quenching ROS through inhibiting RAC1 and its potential value for prognosis estimation and targeted therapy.

Loss of cell-cell adhesion triggers cell migration through Rac1-dependent ROS generation

Epithelial cells usually trigger their "migratory machinery" upon loss of adhesion to their neighbors. This default is important for both physiological (e.g., wound healing) and pathological (e.g., tumor metastasis) processes. However, the underlying mechanism for such a default remains unclear. In this study, we used the human head and neck squamous cell carcinoma (HNSCC) SAS cells as a model and found that loss of cell-cell adhesion induced reactive oxygen species (ROS) generation and vimentin expression, both of which were required for SAS cell migration upon loss of cell-cell adhesion. We demonstrated that Tiam1-mediated Rac1 activation was responsible for the ROS generation through NADPH-dependent oxidases. Moreover, the ROS-Src-STAT3 signaling pathway that led to vimentin expression was important for SAS cell migration. The activation of ROS, Src, and STAT3 was also detected in tumor biopsies from HNSCC patients. Notably, activated STAT3 was more abundant at the tumor invasive front and correlated with metastatic progression of HNSCC. Together, our results unveil a mechanism of how cells trigger their migration upon loss of cell-cell adhesion and highlight an important role of the ROS-Src-STAT3 signaling pathway in the progression of HNSCC.

Caveolin-1 signaling-driven mitochondrial fission and cytoskeleton remodeling promotes breast cancer migration

Mitochondria are highly dynamic organelles that constantly divide and fuse to maintain their proper structure and function. Cancer cells are often accompanied by an imbalance of mitochondrial fusion and fission, cancer progression is greatly affected by this imbalance. Here, we found that high-metastatic breast cancer MDA-MB-231 cells possess higher caveolin-1 (Cav-1) expression compared with low-metastatic breast cancer MCF-7 cells or normal breast epithelial MCF-10A cells. Downregulation of Cav-1 decreases the migratory and invasive abilities of MDA-MB-231 cells. Our results further demonstrated that downregulation of Cav-1 facilitated DRP1 and MFN2 to translocate to mitochondria, increasing the inhibitory phosphorylation level of DRP1 at Ser637 by protein kinase A (PKA), resulting in mitochondria elongation. We also showed that downregulation of Cav-1 significantly reduced the Rac1 activity by affecting intracellular reactive oxygen species (ROS) generation, which then inhibited F-actin formation. Based on these findings, we proposed that Cav-1 mediated mitochondrial fission-affected intracellular ROS generation and activated Rho GTPases, leading to F-actin-dependent formation of lamellipodia and promotion of breast cancer motility.

How Nanoparticles Open the Paracellular Route of Biological Barriers: Mechanisms, Applications, and Prospects

Biological barriers are essential physiological protective systems and obstacles to drug delivery. Nanoparticles (NPs) can access the paracellular route of biological barriers, either causing adverse health impacts on humans or producing therapeutic opportunities. This Review introduces the structural and functional influences of NPs on the key components that govern the paracellular route, mainly tight junctions, adherens junctions, and cytoskeletons. Furthermore, we evaluate their interaction mechanisms and address the influencing factors that determine the ability of NPs to open the paracellular route, which provides a better knowledge of how NPs can open the paracellular route in a safer and more controllable way. Finally, we summarize limitations in the research models and methodologies of the existing research in the field and provide future research direction. This Review demonstrates the in-depth causes for the reversible opening or destruction of the integrity of barriers generated by NPs; more importantly, it contributes insights into the design of NP-based medications to boost paracellular drug delivery efficiency.

NMDA receptors mediate synaptic plasticity impairment of hippocampal neurons due to arsenic exposure

Endemic arsenism is a worldwide health problem. Chronic arsenic exposure results in cognitive dysfunction due to arsenic and its metabolites accumulating in hippocampus. As the cellular basis of cognition, synaptic plasticity is pivotal in arsenic-induced cognitive dysfunction. N-methyl-D-aspartate receptors (NMDARs) serve physiological functions in synaptic transmission. However, excessive NMDARs activity contributes to exitotoxicity and synaptic plasticity impairment. Here, we provide an overview of the mechanisms that NMDARs and their downstream signaling pathways mediate synaptic plasticity impairment due to arsenic exposure in hippocampal neurons, ways of arsenic exerting on NMDARs, as well as the potential therapeutic targets except for water improvement.

PUFA-Derived N-Acylethanolamide Probes Identify Peroxiredoxins and Small GTPases as Molecular Targets in LPS-Stimulated RAW264.7 Macrophages

We studied the mechanistic and biological origins of anti-inflammatory poly-unsaturated fatty acid-derived N-acylethanolamines using synthetic bifunctional chemical probes of docosahexaenoyl ethanolamide (DHEA) and arachidonoyl ethanolamide (AEA) in RAW264.7 macrophages stimulated with 1.0 μg mL^-1 lipopolysaccharide. Using a photoreactive diazirine, probes were covalently attached to their target proteins, which were further studied by introducing a fluorescent probe or biotin-based affinity purification. Fluorescence confocal microscopy showed DHEA and AEA probes localized in cytosol, specifically in structures that point toward the endoplasmic reticulum and in membrane vesicles. Affinity purification followed by proteomic analysis revealed peroxiredoxin-1 (Prdx1) as the most significant binding interactor of both DHEA and AEA probes. In addition, Prdx4, endosomal related proteins, small GTPase signaling proteins, and prostaglandin synthase 2 (Ptgs2, also known as cyclooxygenase 2 or COX-2) were identified. Lastly, confocal fluorescence microscopy revealed the colocalization of Ptgs2 and Rac1 with DHEA and AEA probes. These data identified new molecular targets suggesting that DHEA and AEA may be involved in reactive oxidation species regulation, cell migration, cytoskeletal remodeling, and endosomal trafficking and support endocytosis as an uptake mechanism.

The E3 ubiquitin ligase MG53 inhibits hepatocellular carcinoma by targeting RAC1 signaling

Ras-related C3 botulinum toxin substrate 1 (RAC1) overexpressiosn and hyperactivation are correlated with aggressive growth and other malignant characteristics in a wide variety of cancers including hepatocellular carcinoma (HCC). However, the regulatory mechanism of RAC1 expression and activation in HCC is not fully understood. Here, we demonstrated that E3 ubiquitin ligase MG53 (also known as tripartite motif 72, TRIM72) acted as a direct inhibitor of RAC1, and it catalyzed the ubiquitination of RAC1 and further inhibited RAC1 activity in HCC cells. Mechanistically, MG53 directly bound with RAC1 through its coiled-coil domain and suppressed RAC1 activity by catalyzing the Lys48 (K48)-linked polyubiquitination of RAC1 at Lys5 residue in HCC cells. We further demonstrated that MG53 significantly suppressed the malignant behaviors of HCC cells and enhanced the chemosensitivity of HCC cells to sorafenib treatment by inhibiting RAC1-MAPK signaling axis. In summary, we identified MG53 as a novel RAC1 inhibitor and tumor suppressor in HCC, and it suppressed HCC progression by inducing K48-linked polyubiquitination of RAC1 and further inhibiting the RAC1-MAPK signaling. Altogether, our investigation provided a new therapeutic strategy for RAC1 overactivated tumors by modulating MG53.

Oxidation and reduction of actin: Origin, impact in vitro and functional consequences in vivo

Actin is among the most abundant proteins in eukaryotic cells and assembles into dynamic filamentous networks regulated by many actin binding proteins. The actin cytoskeleton must be finely tuned, both in space and time, to fulfill key cellular functions such as cell division, cell shape changes, phagocytosis and cell migration. While actin oxidation by reactive oxygen species (ROS) at non-physiological levels are known for long to impact on actin polymerization and on the cellular actin cytoskeleton, growing evidence shows that direct and reversible oxidation/reduction of specific actin amino acids plays an important and physiological role in regulating the actin cytoskeleton. In this review, we describe which actin amino acid residues can be selectively oxidized and reduced in many different ways (e.g. disulfide bond formation, glutathionylation, carbonylation, nitration, nitrosylation and other oxidations), the cellular enzymes at the origin of these post-translational modifications, and the impact of actin redox modifications both in vitro and in vivo. We show that the regulated balance of oxidation and reduction of key actin amino acid residues contributes to the control of actin filament polymerization and disassembly at the subcellular scale and highlight how improper redox modifications of actin can lead to pathological conditions.

Interactions Between Immunomodulatory Biomaterials and Immune Microenvironment: Cues for Immunomodulation Strategies in Tissue Repair

The foreign body response (FBR) caused by biomaterials can essentially be understood as the interaction between the immune microenvironment and biomaterials, which has severely impeded the application of biomaterials in tissue repair. This concrete interaction occurs via cells and bioactive substances, such as proteins and nucleic acids. These cellular and molecular interactions provide important cues for determining which element to incorporate into immunomodulatory biomaterials (IMBs), and IMBs can thus be endowed with the ability to modulate the FBR and repair damaged tissue. In terms of cellular, IMBs are modified to modulate functions of immune cells, such as macrophages and mast cells. In terms of bioactive substances, proteins and nucleic acids are delivered to influence the immune microenvironment. Meanwhile, IMBs are designed with high affinity for spatial targets and the ability to self-adapt over time, which allows for more efficient and intelligent tissue repair. Hence, IMB may achieve the perfect functional integration in the host, representing a breakthrough in tissue repair and regeneration medicine.

Reciprocal Regulation of Shh Trafficking and H2O2 Levels via a Noncanonical BOC-Rac1 Pathway

Among molecules that bridge environment, cell metabolism, and cell signaling, hydrogen peroxide (H₂O₂) recently appeared as an emerging but central player. Its level depends on cell metabolism and environment and was recently shown to play key roles during embryogenesis, contrasting with its long-established role in disease progression. We decided to explore whether the secreted morphogen Sonic hedgehog (Shh), known to be essential in a variety of biological processes ranging from embryonic development to adult tissue homeostasis and cancers, was part of these interactions. Here, we report that H₂O₂ levels control key steps of Shh delivery in cell culture: increased levels reduce primary secretion, stimulate endocytosis and accelerate delivery to recipient cells; in addition, physiological in vivo modulation of H₂O₂ levels changes Shh distribution and tissue patterning. Moreover, a feedback loop exists in which Shh trafficking controls H₂O₂ synthesis via a non-canonical BOC-Rac1 pathway, leading to cytoneme growth. Our findings reveal that Shh directly impacts its own distribution, thus providing a molecular explanation for the robustness of morphogenesis to both environmental insults and individual variability.

Mycotoxin deoxynivalenol affects myoblast differentiation via downregulating cytoskeleton and ECM-integrin-FAK-RAC-PAK signaling pathway

As a common mycotoxin, deoxynivalenol (DON) contaminates cereal grains and feed in field or during processing and storage. DON elicits a spectrum of adverse effects in animals including anorexia and growth retardation. Especially, the presence of DON has also been detected in muscle, suggesting that DON may has the potential to affect the development of muscle. However, the relevant research is very rare and the molecular mechanism remains unclear. Myoblasts differentiation into multinucleated myotubes is one of the crucial steps of skeletal muscle development. In the present study, we investigated the effects of DON on differentiation of myoblasts using murine C2C12 cells model. The results indicated that DON dose-dependent inhibited the formation of myotubes in C2C12 cells. After performing omics techniques, a total of 149 differentially expressed genes were identified. The expression of cytoskeleton proteins and extracellular matrix (ECM) proteins were downregulated by DON. Furthermore, DON significantly downregulated the expression of integrin αv and integrin β5, leading to inhibition of the ECM-integrin receptor interaction. The focal adhesion kinase (FAK) and phosphorylated forms, ras-related C3 botulinum toxin substrate (RAC) and p21-activated kinases 1 (PAK1) were also downregulated by DON. Taken together, our findings suggest that DON has the potent to affect the differentiation of myoblasts via downregulating of cytoskeleton and ECM-integrin-FAK-RAC-PAK signaling pathway.

Disturbed flow-induced FAK K152 SUMOylation initiates the formation of pro-inflammation positive feedback loop by inducing reactive oxygen species production in endothelial cells

Focal adhesion kinase (FAK) activation plays a crucial role in vascular diseases. In endothelial cells, FAK activation is involved in the activation of pro-inflammatory signaling and the progression of atherosclerosis. Disturbed flow (D-flow) induces endothelial activation and senescence, but the exact role of FAK in D-flow-induced endothelial activation and senescence remains unclear. The objective of this study is to investigate the role of FAK SUMOylation in D-flow-induced endothelial activation and senescence. The results showed that D-flow induced reactive oxygen species (ROS) production via NADPH oxidase activation and activated a redox-sensitive kinase p90RSK, leading to FAK activation by upregulating FAK K152 SUMOylation and the subsequent Vav2 phosphorylation, which in turn formed a positive feedback loop by upregulating ROS production. This feedback loop played a crucial role in regulating endothelial activation and senescence. D-flow-induced endothelial activation and senescence were significantly inhibited by mutating a FAK SUMOylation site lysine152 to arginine. Collectively, we concluded that FAK K152 SUMOylation plays a key role in D-flow-induced endothelial activation and senescence by forming a positive feedback loop through ROS production.

Rac GTPase Signaling in Immune-Mediated Mechanisms of Atherosclerosis

Coronary artery disease caused by atherosclerosis is a major cause of morbidity and mortality around the world. Data from preclinical and clinical studies support the belief that atherosclerosis is an inflammatory disease that is mediated by innate and adaptive immune signaling mechanisms. This review sought to highlight the role of Rac-mediated inflammatory signaling in the mechanisms driving atherosclerotic calcification. In addition, current clinical treatment strategies that are related to targeting hypercholesterolemia as a critical risk factor for atherosclerotic vascular disease are addressed in relation to the effects on Rac immune signaling and the implications for the future of targeting immune responses in the treatment of calcific atherosclerosis.

H9c2 Cardiomyocytes under Hypoxic Stress: Biological Effects Mediated by Sentinel Downstream Targets

The association between diabetes and cardiovascular diseases is well known. Related diabetes macro- and microangiopathies frequently induce hypoxia and consequently energy failure to satisfy the jeopardized myocardium basal needs. Additionally, it is widely accepted that diabetes impairs endothelial nitric oxide synthase (eNOS) activity, resulting in diminished nitric oxide (NO) bioavailability and consequent endothelial cell dysfunction. In this study, we analyzed the embryonic heart-derived H9c2 cell response to hypoxic stress after administration of a high glucose concentration to reproduce a condition often observed in diabetes. We observed that 24 h hypoxia exposure of H9c2 cells reduced cell viability compared to cells grown in normoxic conditions. Cytotoxicity and early apoptosis were increased after exposure to high glucose administration. In addition, hypoxia induced a RhoA upregulation and a Bcl-2 downregulation and lowered the ERK activation observed in normoxia at both glucose concentrations. Furthermore, a significant cell proliferation rate increases after the 1400 W iNOS inhibitor administration was observed. Again, hypoxia increased the expression level of myogenin, a marker of skeletal muscle cell differentiation. The cardiomyocyte gene expression profiles and morphology changes observed in response to pathological stimuli, as hypoxia, could lead to improper ventricular remodeling responsible for heart failure. Therefore, understanding cell signaling events that regulate cardiac response to hypoxia could be useful for the discovery of novel therapeutic approaches able to prevent heart diseases.

Inhibition of RAC1 activity in cancer associated fibroblasts favours breast tumour development through IL-1β upregulation

Cancer-associated fibroblasts (CAFs) are highly abundant stromal components in the tumour microenvironment. These cells contribute to tumorigenesis and indeed, they have been proposed as a target for anti-cancer therapies. Similarly, targeting the Rho-GTPase RAC1 has also been suggested as a potential therapeutic target in cancer. Here, we show that targeting RAC1 activity, either pharmacologically or by genetic silencing, increases the pro-tumorigenic activity of CAFs by upregulating IL-1β secretion. Moreover, inhibiting RAC1 activity shifts the CAF subtype to a more aggressive phenotype. Thus, as RAC1 suppresses the secretion of IL-1β by CAFs, reducing RAC1 activity in combination with the depletion of this cytokine should be considered as an interesting therapeutic option for breast cancer in which tumour cells retain intact IL-1β signalling.

Intersection of Redox Chemistry and Ubiquitylation: Post-Translational Modifications Required for Maintaining Cellular Homeostasis and Neuroprotection

Neurodegeneration has been predominantly recognized as neuronal breakdown induced by the accumulation of aggregated and/or misfolded proteins and remains a preliminary factor in age-dependent disease. Recently, critical regulating molecular mechanisms and cellular pathways have been shown to induce neurodegeneration long before aggregate accumulation could occur. Although this opens the possibility of identifying biomarkers for early onset diagnosis, many of these pathways vary in their modes of dysfunction while presenting similar clinical phenotypes. With selectivity remaining difficult, it is promising that these neuroprotective pathways are regulated through the ubiquitin-proteasome system (UPS). This essential post-translational modification (PTM) involves the specific attachment of ubiquitin onto a substrate, specifically marking the ubiquitin-tagged protein for its intracellular fate based upon the site of attachment, the ubiquitin chain type built, and isopeptide linkages between different ubiquitin moieties. This review highlights both the direct and indirect impact ubiquitylation has in oxidative stress response and neuroprotection, and how irregularities in these intricate processes lead towards the onset of neurodegenerative disease (NDD).

Resveratrol suppresses malignant progression of oral squamous cell carcinoma cells by inducing the ZNF750/RAC1 signaling pathway

This study examined whether activation of zinc finger protein 750/Ras-related C3 botulinum toxin substrate 1 (ZNF750/RAC1) signaling pathway may be involved in the ability of resveratrol to inhibit malignant progression of CAL-27 oral squamous cell carcinoma cells. CAL-27 cells were treated with resveratrol and transfected with plasmids expressing a ZNF750 mimic or ZNF750 inhibitor. Cell proliferation and apoptosis were assessed. Western blotting was used to examine the effects of resveratrol on levels of angiogenin, vascular endothelial growth factor (VEGF), prolyl hydroxylase 2 (PHD2), G protein signal-regulated protein 5 (RGS5), integrin A5 (ITGA5), integrin B1 (ITGB1), CD44, RAC1, and ZNF750. Quantitative PCR was used to examine the effects on mRNA levels of platelet-derived growth factor (PDGFB), tumor vascular marker CD105, and cell adhesion molecules ITGA5, ITGB1, and CD44. Resveratrol downregulated angiogenin, VEGF, RGS5, CD105, and the cell adhesion molecules ITGA5, ITGB1, and CD44 expressions to inhibit the vascular normalization, metastasis, adhesion, and migration of CAL-27 cells. Conversely, it upregulated ZNF750, PHD2, and PDGFB to suppress the malignant progression of CAL-27 cells. We further observed that these changes were associated with reduced proliferation, reduced colony formation, and increased apoptosis in cancer cells. ZNF750 silencing partly reversed these effects of resveratrol on the proliferation and apoptosis of CAL-27 cells. Additionally, RAC1 agonist also weakened these impacts of resveratrol on the growth of CAL-27 cells. The ability of resveratrol to suppress the progression of oral squamous cell carcinoma may involve activation of the ZNF750/RAC1 signaling pathway and modification of the tumor vascular microenvironment.

Nox2 impairs VEGF-A-induced angiogenesis in placenta via mitochondrial ROS-STAT3 pathway

Aberrant placental angiogenesis is associated with fetal intrauterine growth restriction (IUGR), but the mechanism underlying abnormal placental angiogenesis remains largely unknown. Here, lower vessel density and higher expression of NADPH oxidases 2 (Nox2) were observed in the placentae for low birth weight (LBW) fetuses versus normal birth weight (NBW) fetuses, with a negative correlation between Nox2 and placental vessel density. Moreover, it was revealed for the first time that Nox2 deficiency facilitates angiogenesis in vitro and in vivo, and vascular endothelial growth factor-A (VEGF-A) has an essential role in Nox2-controlled inhibition of angiogenesis in porcine vascular endothelial cells (PVECs). Mechanistically, Nox2 inhibited phospho-signal transducer and activator of transcription 3 (p-STAT3) in the nucleus by inducing the production of mitochondrial reactive oxygen species (ROS). Dual-luciferase assay confirmed that knockdown of Nox2 reduces the expression of VEGF-A in an STAT3 dependent manner. Our results indicate that Nox2 is a potential target for therapy by increasing VEGF-A expression to promote angiogenesis and serves as a prognostic indicator for fetus with IUGR.

Sodium Glucose Co-Transporter 2 Inhibitors Ameliorate Endothelium Barrier Dysfunction Induced by Cyclic Stretch through Inhibition of Reactive Oxygen Species

SGLT-2i's exert direct anti-inflammatory and anti-oxidative effects on resting endothelial cells. However, endothelial cells are constantly exposed to mechanical forces such as cyclic stretch. Enhanced stretch increases the production of reactive oxygen species (ROS) and thereby impairs endothelial barrier function. We hypothesized that the SGLT-2i's empagliflozin (EMPA), dapagliflozin (DAPA) and canagliflozin (CANA) exert an anti-oxidative effect and alleviate cyclic stretch-induced endothelial permeability in human coronary artery endothelial cells (HCAECs). HCAECs were pre-incubated with one of the SGLT-2i's (1 µM EMPA, 1 µM DAPA and 3 µM CANA) for 2 h, followed by 10% stretch for 24 h. HCAECs exposed to 5% stretch were considered as control. Involvement of ROS was measured using N-acetyl-l-cysteine (NAC). The sodium-hydrogen exchanger 1 (NHE1) and NADPH oxidases (NOXs) were inhibited by cariporide, or GKT136901, respectively. Cell permeability and ROS were investigated by fluorescence intensity imaging. Cell permeability and ROS production were increased by 10% stretch; EMPA, DAPA and CANA decreased this effect significantly. Cariporide and GKT136901 inhibited stretch-induced ROS production but neither of them further reduced ROS production when combined with EMPA. SGLT-2i's improve the barrier dysfunction of HCAECs under enhanced stretch and this effect might be mediated through scavenging of ROS. Anti-oxidative effect of SGLT-2i's might be partially mediated by inhibition of NHE1 and NOXs.

Oxidative Stress and Hypertension

A link between oxidative stress and hypertension has been firmly established in multiple animal models of hypertension but remains elusive in humans. While initial studies focused on inactivation of nitric oxide by superoxide, our understanding of relevant reactive oxygen species (superoxide, hydrogen peroxide, and peroxynitrite) and how they modify complex signaling pathways to promote hypertension has expanded significantly. In this review, we summarize recent advances in delineating the primary and secondary sources of reactive oxygen species (nicotinamide adenine dinucleotide phosphate oxidases, uncoupled endothelial nitric oxide synthase, endoplasmic reticulum, and mitochondria), the posttranslational oxidative modifications they induce on protein targets important for redox signaling, their interplay with endogenous antioxidant systems, and the role of inflammasome activation and endoplasmic reticular stress in the development of hypertension. We highlight how oxidative stress in different organ systems contributes to hypertension, describe new animal models that have clarified the importance of specific proteins, and discuss clinical studies that shed light on how these processes and pathways are altered in human hypertension. Finally, we focus on the promise of redox proteomics and systems biology to help us fully understand the relationship between ROS and hypertension and their potential for designing and evaluating novel antihypertensive therapies.

GTPases, genome, actin: A hidden story in DNA damage response and repair mechanisms

The classical small Rho GTPase (Rho, Rac, and Cdc42) protein family is mainly responsible for regulating cell motility and polarity, membrane trafficking, cell cycle control, and gene transcription. Cumulative recent evidence supports important roles for these proteins in the maintenance of genomic stability. Indeed, DNA damage response (DDR) and repair mechanisms are some of the prime biological processes that underlie several disease phenotypes, including genetic disorders, cancer, senescence, and premature aging. Many reports guided by different experimental approaches and molecular hypotheses have demonstrated that, to some extent, direct modulation of Rho GTPase activity, their downstream effectors, or actin cytoskeleton regulation contribute to these cellular events. Although much attention has been paid to this family in the context of canonical actin cytoskeleton remodeling, here we provide a contextualized review of the interplay between Rho GTPase signaling pathways and the DDR and DNA repair signaling components. Interesting questions yet to be addressed relate to the spatiotemporal dynamics of this collective response and whether it correlates with different subcellular pools of Rho GTPases. We highlight the direct and indirect targets, some of which still lack experimental validation data, likely associated with Rho GTPase activation that provides compelling evidence for further investigation in DNA damage-associated events and with potential therapeutic applications in translational medicine.

Protective Role of Polyphenols in Heart Failure: Molecular Targets and Cellular Mechanisms Underlying Their Therapeutic Potential

Heart failure (HF) is a leading cause of death in the United States, with a 5-year mortality rate of 50% despite modern pharmacological therapies. Plant-based diets are comprised of a diverse polyphenol profile, which lends to their association with reduced cardiovascular disease risk. Whether a polyphenol-rich diet can slow the progression of or reverse HF in humans is not known. To date, in vitro and in vivo studies have reported on the protective role of polyphenols in HF. In this review, we will discuss the major mechanisms by which polyphenols mitigate HF in vitro and in vivo, including (1) reduced cardiac inflammation and oxidative stress, (2) reduced mitochondrial dysfunction, (3) improved Ca²⁺ homeostasis, (4) increased survival signaling, and (5) increased sirtuin 1 activity.

Exosomes containing miR-451a is involved in the protective effect of cerebral ischemic preconditioning against cerebral ischemia and reperfusion injury

Aim

To study the role of exosomes in the protective effect of cerebral ischemic preconditioning (cerebral‐IPC) against cerebral I/R injury.

Method

Mouse models of cerebral‐IPC and MCAO/R were established as described previously, and their behavioral, pathological, and proteomic changes were analyzed. Neuro‐2a subjected to OGD/R were treated with exosomes isolated from the plasma of sham‐operated and cerebral‐IPC mice. The differentially expressed miRNAs between exosomes derived from sham‐operated (S‐exosomes) and preconditioned (IPC‐exosomes) mice were identified through miRNA array, and their targets were identified through database search. The control and OGD/R cells were treated with the IPC‐exosomes, miRNA mimic or target protein inhibitor, and their viability, oxidative, stress and apoptosis rates were measured. The activated pathways were identified by analyzing the levels of relevant proteins.

Results

Cerebral‐IPC mitigated the cerebral injury following ischemia and reperfusion, and increased the number of plasma exosomes. IPC‐exosomes increased the survival of Neuro‐2a cells after OGD/R. The miR‐451a targeting Rac1 was upregulated in the IPC‐exosomes relative to S‐exosomes. The miR‐451a mimic and the Rac1 inhibitor NSC23766 reversed OGD/R‐mediated activation of Rac1 and its downstream pathways.

Conclusion

Cerebral‐IPC ameliorated cerebral I/R injury by inducing the release of exosomes containing miR‐451a.

Excavating bioactivities of nanozyme to remodel microenvironment for protecting chondrocytes and delaying osteoarthritis

Osteoarthritis (OA) is the main cause of disability in the elderly. Effective intervention in the early and middle stage of osteoarthritis can greatly prevent or slow down the development of the disease, and reduce the probability of joint replacement. However, there is to date no effective intervention for early and middle-stage OA. OA microenvironment mainly destroys the balance of oxidative stress, extracellular matrix synthesis and degradation of chondrocytes under the joint action of biological and mechanical factors. Herein, hollow Prussian blue nanozymes (HPBzymes) were designed via a modified hydrothermal template-free method. The aim of this study was to investigate the effects of HPBzymes on chondrocytes and the progression of OA. The intrinsic bioactivities of HPBzymes were excavated in vitro and in vivo, remodeling microenvironment for significantly protecting chondrocytes and delaying the progression of traumatic OA by inhibiting reactive oxygen species (ROS) and Rac1/nuclear factor kappa-B (NF-κB) signaling in a rat model. HPBzyme significantly diminished interleukin (IL)-1β-stimulated inflammation, extracellular matrix degradation, and apoptosis of human chondrocytes. HPBzyme attenuated the expression of Rac1 and the ROS levels and prevented the release and nuclear translocation of NF-κB. Deeply digging the intrinsic bioactivities of nanozyme with single component to remodel microenvironment is an effective strategy for ROS-associated chronic diseases. This study reveals that excavating the bioactivities of nanomedicine deserves attention for diagnosis and treatment of severe diseases.

Tumor necrosis factor-α requires Ezrin to regulate the cytoskeleton and cause pulmonary microvascular endothelial barrier damage

Acute respiratory distress syndrome (ARDS) is a rapidly progressive disease with unknown pathogenesis. Damage of pulmonary microvascular endothelial cells (PMVECs) caused by inflammatory storm caused by cytokines such as TNF-α is the potential pathogenesis of ARDS. In this study, we examined the role of ezrin and Rac1 in TNF-α-related pathways, which regulates the permeability of PMVECs. Primary rat pulmonary microvascular endothelial cells (RPMVECs) were isolated and cultured. RPMVECs were treated with rat TNF-α (0, 1, 10, 100 ng/ml), and the cell activity of each group was measured using a CCK8 kit. The integrity of endothelial barrier was measured by transendothelial resistance (TEER) and FITC-BSA flux across RPMVECs membranes. Pulldown assay and Western blot was used to detect the activity of RAS-associated C3 botulinum toxin substrate 1 (Rac1) and Ezrin phosphorylation. Short hairpin RNA (shRNA) targeting ezrin and Rac1 was utilized to evaluate the effect of RPMVECs permeability and related pathway. The effects of ezrin and Rac1 on cytoskeleton were confirmed by immunofluorescence. Our results revealed that active Rac1 was essential for protecting the RPMVEC barrier stimulated by TNF-α, while active ezrin could partially destroy the PMVEC barrier by reducing Rac1 activity and regulating the subcellular structure of the cytoskeleton. These findings may be used to create new therapeutic strategies for targeting Rac1 in the treatment of ARDS.

The Regulatory Role of Rho GTPases and their Substrates in Osteoclastogenesis

Pathological bone loss diseases (osteolysis, Paget's diseases) are commonly caused by the excessive differentiation and activity of osteoclasts. The Rho GTPases family members Rac1/2 (Rac1 and Rac2) have been reported for their special role in exerting multiple cellular functions during osteoclastic differentiation, which includes the most prominent function on dynamic actin cytoskeleton rearranging. Besides that, the increasing studies demonstrated that the regulating effects of Rac1/2 on the osteoclastic cytoskeletal organization are through the GEFs member Dock5. Although the amount of relevant studies on this topic is still limited, several excellent studies have been reported that extensively explored the molecular mechanisms involved in Rac1/2 and Dock5 during the osteoclastogenesis regulation, as well as their role as the therapeutic target in bone loss diseases. Herein, in this review, we aim to focus on recent advances studies for extensively understanding the role of Rho GTPases Rac1/2 and Dock5 in osteoclastogenesis, as well as their role as a potential therapeutic target in regulating osteoclastogenesis.

The potential role of dietary advanced glycation endproducts in the development of chronic non-infectious diseases: a narrative review

Increasing clinical and experimental evidence accumulated during the past few decades supports an important role for dietary advanced glycation endproducts (AGE) in the pathogenesis of many chronic non-infectious diseases, such as type 2 diabetes, CVD and others, that are reaching epidemic proportions in the Western world. Although AGE are compounds widely recognised as generated in excess in the body in diabetic patients, the potential importance of exogenous AGE, mostly of dietary origin, has been largely ignored in the general nutrition audience. In the present review we aim to describe dietary AGE, their mechanisms of formation and absorption into the body as well as their main mechanisms of action. We will present in detail current evidence of their potential role in the development of several chronic non-infectious clinical conditions, some general suggestions on how to restrict them in the diet and evidence regarding the potential benefits of lowering their consumption.

TRP Channels Regulation of Rho GTPases in Brain Context and Diseases

Neurological and neuropsychiatric disorders are mediated by several pathophysiological mechanisms, including developmental and degenerative abnormalities caused primarily by disturbances in cell migration, structural plasticity of the synapse, and blood-vessel barrier function. In this context, critical pathways involved in the pathogenesis of these diseases are related to structural, scaffolding, and enzymatic activity-bearing proteins, which participate in Ca²⁺- and Ras Homologs (Rho) GTPases-mediated signaling. Rho GTPases are GDP/GTP binding proteins that regulate the cytoskeletal structure, cellular protrusion, and migration. These proteins cycle between GTP-bound (active) and GDP-bound (inactive) states due to their intrinsic GTPase activity and their dynamic regulation by GEFs, GAPs, and GDIs. One of the most important upstream inputs that modulate Rho GTPases activity is Ca²⁺ signaling, positioning ion channels as pivotal molecular entities for Rho GTPases regulation. Multiple non-selective cationic channels belonging to the Transient Receptor Potential (TRP) family participate in cytoskeletal-dependent processes through Ca²⁺-mediated modulation of Rho GTPases. Moreover, these ion channels have a role in several neuropathological events such as neuronal cell death, brain tumor progression and strokes. Although Rho GTPases-dependent pathways have been extensively studied, how they converge with TRP channels in the development or progression of neuropathologies is poorly understood. Herein, we review recent evidence and insights that link TRP channels activity to downstream Rho GTPase signaling or modulation. Moreover, using the TRIP database, we establish associations between possible mediators of Rho GTPase signaling with TRP ion channels. As such, we propose mechanisms that might explain the TRP-dependent modulation of Rho GTPases as possible pathways participating in the emergence or maintenance of neuropathological conditions.

Effects of RAC1 on Proliferation of Hen Ovarian Prehierarchical Follicle Granulosa Cells

Simple Summary

The growth and development of ovary follicles is an intricate, highly organized process involving many local intra-ovarian factors. Ras-related C3 botulinum toxin substrate1 (RAC1) is speculated to be associated with prehierarchical follicle development of hen ovaries. The current study initially revealed RAC1 mRNA to be expressed in varied-size follicles and stroma and its expression levels in the prehierarchical follicles of 1.0–3.9 mm, 6.0–6.9 mm and 7.0–8.0 mm in diameter were remarkably higher than the other groups. Moreover, RAC1 protein was mainly expressed in the oocytes and granulosa cells (GC), as well as in stromal tissues of the follicles. To understand the exact roles of the RAC1 gene in regulation of follicular GC proliferation and differentiation, siRNA interference and overexpression of the RAC1 gene were conducted. Our experiments demonstrated that the RAC1 gene can significantly promote the expression of mRNA and proteins of FSHR, CCND2, CYP11A1, PCNA and StAR genes in GC and directly elevate the proliferation of GC in vitro. These results indicated RAC1 played a crucial role in regulation of GC proliferation and differentiation and steroidogenesis during the development of prehierarchical follicles. This study provided a base for elucidating the molecular mechanisms underlying the biological effect of RAC1 on the hen ovary follicle growth and development.

Abstract

RAC1 belongs to the small G protein Rho subfamily and is implicated in regulating gene expression, cell proliferation and differentiation in mammals and humans; nevertheless, the function of RAC1 in growth and development of hen ovarian follicles is still unclear. This study sought to understand the biological effects of RAC1 on granulosa cell (GC) proliferation and differentiation of hen ovarian prehierarchical follicles. Firstly, our results showed expression levels of RAC1 mRNA in the follicles with diameters of 7.0–8.0 mm, 6.0–6.9 mm and 1.0–3.9 mm were greater than other follicles (p < 0.05). The RAC1 protein was mainly expressed in oocyte and its around GCs and stromal tissues of the prehierarchical follicles by immunohistochemistry. Further investigation revealed the RAC1 gene remarkably enhanced the mRNA and protein expression levels of FSHR (a marker of follicle selection), CCND2 (a marker of cell-cycle progression and GC differentiation), PCNA (a marker of GC proliferation), StAR and CYP11A1 (markers of GC differentiation and steroidogenesis) (p < 0.05). Furthermore, our data demonstrated siRNA interference of RAC1 significantly reduced GC proliferation (p < 0.05), while RAC1 gene overexpression enhanced GC proliferation in vitro (p < 0.05). Collectively, this study provided new evidence that the biological effects of RAC1 on GC proliferation, differentiation and steroidogenesis of chicken ovary follicles.

Neuronal Signaling Involved in Neuronal Polarization and Growth: Lipid Rafts and Phosphorylation

Neuronal polarization and growth are developmental processes that occur during neuronal cell differentiation. The molecular signaling mechanisms involved in these events in in vivo mammalian brain remain unclear. Also, cellular events of the neuronal polarization process within a given neuron are thought to be constituted of many independent intracellular signal transduction pathways (the "tug-of-war" model). However, in vivo results suggest that such pathways should be cooperative with one another among a given group of neurons in a region of the brain. Lipid rafts, specific membrane domains with low fluidity, are candidates for the hotspots of such intracellular signaling. Among the signals reported to be involved in polarization, a number are thought to be present or translocated to the lipid rafts in response to extracellular signals. As part of our analysis, we discuss how such novel molecular mechanisms are combined for effective regulation of neuronal polarization and growth, focusing on the significance of the lipid rafts, including results based on recently introduced methods.

IQGAP1 causes choroidal neovascularization by sustaining VEGFR2-mediated Rac1 activation

Loss of visual acuity in neovascular age-related macular degeneration (nAMD) occurs when factors activate choroidal endothelial cells (CECs) to transmigrate the retinal pigment epithelium into the sensory retina and develop into choroidal neovascularization (CNV). Active Rac1 (Rac1GTP) is required for CEC migration and is induced by different AMD-related stresses, including vascular endothelial growth factor (VEGF). Besides its role in pathologic events, Rac1 also plays a role in physiologic functions. Therefore, we were interested in a method to inhibit pathologic activation of Rac1. We addressed the hypothesis that IQGAP1, a scaffold protein with a Rac1 binding domain, regulates pathologic Rac1GTP in CEC migration and CNV. Compared to littermate Iqgap1^+/+, Iqgap1^-/- mice had reduced volumes of laser-induced CNV and decreased Rac1GTP and phosphorylated VEGFR2 (p-VEGFR2) within lectin-stained CNV. Knockdown of IQGAP1 in CECs significantly reduced VEGF-induced Rac1GTP, mediated through p-VEGFR2, which was necessary for CEC migration. Moreover, sustained activation of Rac1GTP induced by VEGF was eliminated when CECs were transfected with an IQGAP1 construct that is unable to bind Rac1. IQGAP1-mediated Src activation was involved in initiating Rac1 activation, CEC migration, and tube formation. Our findings indicate that CEC IQGAP1 interacts with VEGFR2 to mediate Src activation and subsequent Rac1 activation and CEC migration. In addition, IQGAP1 binding to Rac1GTP results in sustained activation of Rac1, leading to CEC migration toward VEGF. Our study supports a role of IQGAP1 and the interaction between IQGAP1 and Rac1GTP to restore CECs quiescence and, therefore, prevent vision-threatening CNV in nAMD.

Redox modifications in synaptic components as biomarkers of cognitive status, in brain aging and disease

Aging is a natural process that includes several changes that gradually make organisms degenerate and die. Harman's theory proposes that aging is a consequence of the progressive accumulation of oxidative modifications mediated by reactive oxygen/nitrogen species, which plays an essential role in the development and progression of many neurodegenerative diseases. This review will focus on how abnormal redox modifications induced by age impair the functionality of neuronal redox-sensitive proteins involved in axonal elongation and guidance, synaptic plasticity, and intercellular communication. We will discuss post-transcriptional regulation of gene expression by microRNAs as a mechanism that controls the neuronal redox state. Finally, we will discuss how some brain-permeant antioxidants from the diet have a beneficial effect on cognition. Taken together, the evidence revised here indicates that oxidative-driven modifications of specific proteins and changes in microRNA expression may be useful biomarkers for aging and neurodegenerative diseases. Also, some specific antioxidant therapies have undoubtedly beneficial neuroprotective effects when administered in the correct doses, in the ideal formulation combination, and during the appropriate therapeutic window. The use of some antioxidants is, therefore, still poorly explored for the treatment of neurodegenerative diseases such as Alzheimer's disease.

RAC1mutation is not a predictive biomarker for PI3'-kinase-β-selective pathway-targeted therapy

Mutational activation of RAC1 is detected in ~7% of cutaneous melanoma, with the most frequent mutation (RAC1^C85T ) encoding for RAC1^P29S . RAC1^P29S is a fast-cycling GTPase that leads to accumulation of RAC1^P29S -GTP, which has potentially pleiotropic regulatory functions in melanoma cell signaling and biology. However, the precise mechanism by which mutationally activated RAC1^P29S propagates its pro-tumorigenic effects remains unclear. RAC1-GTP is reported to activate the beta isoform of PI3'-kinase (PIK3CB/PI3Kβ) leading to downstream activation of PI3'-lipid signaling. Hence, we employed both genetic and isoform-selective pharmacological inhibitors to test if RAC1^P29S propagates its oncogenic signaling in melanoma through PI3Kβ. We observed that RAC1^P29S -expressing melanoma cells were largely insensitive to inhibitors of PI3Kβ. Furthermore, RAC1^P29S melanoma cell lines showed variable sensitivity to pan-class 1 (α/β/γ/δ) PI3'-kinase inhibitors, suggesting that RAC1-mutated melanoma cells may not rely on PI3'-lipid signaling for their proliferation. Lastly, we observed that RAC1^P29S -expressing cell lines also showed variable sensitivity to pharmacological inhibition of the RAC1 → PAK1 signaling pathway, questioning the relevance of inhibitors of this pathway for the treatment of patients with RAC1-mutated melanoma.

Delphinidin attenuates pathological cardiac hypertrophy via the AMPK/NOX/MAPK signaling pathway

Reactive oxygen species (ROS) play a pivotal role in the development of pathological cardiac hypertrophy. Delphinidin, a natural flavonoid, was reported to exert marked antioxidative effects. Therefore, we investigated whether delphinidin ameliorates pathological cardiac hypertrophy via inhibiting oxidative stress. In this study, male C57BL/6 mice were treated with DMSO or delphinidin after surgery. Neonatal rat cardiomyocytes (NRCMs) were treated with angiotensin II (Ang II) and delphinidin in vitro. Eighteen-month-old mice were administered delphinidin to investigate the effect of delphinidin on aging-related cardiac hypertrophy. Through analyses of hypertrophic cardiomyocyte growth, fibrosis and cardiac function, delphinidin was demonstrated to confer resistance to aging- and transverse aortic constriction (TAC)-induced cardiac hypertrophy in vivo and attenuate Ang II-induced cardiomyocyte hypertrophy in vitro by significantly suppressing hypertrophic growth and the deposition of fibrosis. Mechanistically, delphinidin reduced ROS accumulation upon Ang II stimulation through the direct activation of AMP-activated protein kinase (AMPK) and subsequent inhibition of the activity of Rac1 and expression of p47^phox. In addition, excessive levels of ERK1/2, P38 and JNK1/2 phosphorylation induced by oxidative stress were abrogated by delphinidin. Delphinidin was conclusively shown to repress pathological cardiac hypertrophy by modulating oxidative stress through the AMPK/NADPH oxidase (NOX)/mitogen-activated protein kinase (MAPK) signaling pathway.