Regulation of RhoA GTPase and novel target proteins for ROCK

Role of RhoA-ROCK signaling inhibitor fasudil in Alzheimer disease

Alzheimer disease (AD) is the most common neurodegenerative brain disease linked with the development of dementia. AD neuropathology is characterized by the progressive accumulation of extracellular β-amyloid (Aβ) plaques and intracellular neurofibrillary tangles (NFTs). Different signaling pathways are involved in AD neuropathology through modulation of Aβ formation and tau protein hyperphosphorylation. One of these signaling is Rho-associated protein kinase (ROCK). RhoA-ROCK signaling boosts the production of Aβ through activation of β-secretase and augments the formation of NFTs. RhoA-ROCK signaling is also intricate in the development of oxidative stress and neuroinflammation. Consequently, targeting RhoA-ROCK signaling by specific inhibitors, such as fasudil, may decrease AD neuropathology. Therefore, this perspective aims to discuss the role of RhoA-ROCK signaling in the pathogenesis of AD and how fasudil could be effective in its treatment.

Ghrelin may protect against vascular endothelial injury in Acute traumatic coagulopathy by mediating the RhoA/ROCK/MLC2 pathway

Ghrelin exerts widespread effects in several diseases, but its role and mechanism in Acute Traumatic Coagulopathy (ATC) are largely unknown. The effect of ghrelin on cell proliferation was examined using three assays: 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), Lactate Dehydrogenase (LDH), and flow cytometry. The barrier function of the endothelial cells was evaluated using the Trans-Endothelial Electrical Resistance (TEER) and the endothelial permeability assay. An ATC mouse model was established to evaluate the in vivo effects of ghrelin. The Ras homolog family member A (RhoA) overexpression plasmid or adenovirus was used to examine the molecular mechanism of ghrelin. Ghrelin enhanced Human Umbilical Vein Endothelial Cells (HUVEC) proliferation and endothelial cell barrier function and inhibited HUVEC permeability damage in vitro. Additionally, ghrelin decreased the activated Partial Thromboplastin Time (aPTT) and Prothrombin Time (PT) in mice blood samples in the ATC mouse model. Ghrelin also improved the pathological alterations in postcava. Mechanistically, ghrelin acts through the RhoA/ Rho-associated Coiled-coil Containing Kinases (ROCK)/ Myosin Light Chain 2 (MLC2) pathway. Furthermore, the protective effects of ghrelin, both in vitro and in vivo, were reversed by RhoA overexpression. Our findings demonstrate that ghrelin may reduce vascular endothelial cell damage and endothelial barrier dysfunction by blocking the RhoA pathway, suggesting that ghrelin may serve as a potential therapeutic target for ATC treatment.

Preliminary study on the cellular and molecular mechanisms of Cms1 ribosomal small subunit homolog promoting hepatocellular carcinoma progression via activation of the homolog family member A/yes-associated protein 1 signaling pathway

Objective

The precise mechanism of action of cms1 ribosomal small subunit homolog (CMSS1) in hepatocellular carcinoma (HCC) is yet unknown, although it may be essential to the malignant evolution of disease. The aim of this study was to reveal the role of CMSS1 in HCC and its possible mechanism.

Material and Methods

The expression of CMSS1 in different HCC cell lines was detected by quantitative real-time polymerase chain reaction and Western blot. The expression of CMSS1 in HCC cells was subsequently silenced, and the proliferation capacity of HCC cells was measured by colony formation assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, and flow cytometry, and the migration and metastasis capacity of the HCC cells was measured by Transwell assay and Western blot. Finally, ras homolog family member A (RhoA) and yes-associated protein 1 (YAP1) were silenced, and the relationship between CMSS1, RhoA, and YAP1 was further discussed by immunofluorescence, colony formation assay, and EdU assay.

Results

The experimental results showed that CMSS1 is highly expressed in HCC tissues and cell lines (P < 0.001). Further experiments demonstrated that CMSS1 promotes the malignant progression of HCC by activating the RhoA GTPase/YAP1 signaling pathway (P < 0.001). Inhibition of YAP1 could reverse the enhanced proliferation and colony formation ability induced by CMSS1 (P < 0.001). Silencing CMSS1 expression can inhibit epithelial- mesenchymal transition (P < 0.01). Moreover, silencing RhoA reduces the YAP1 nuclear translocation (P < 0.001).

Conclusion

CMSS1 promotes the malignant progression of HCC by activating the RhoA GTPase/YAP1 signaling pathway.

PLEKHG1: New Potential Candidate Gene for Periventricular White Matter Abnormalities

Hypoxic-ischemic brain damage presents a significant neurological challenge, often manifesting during the perinatal period. Specifically, periventricular leukomalacia (PVL) is emerging as a notable contributor to cerebral palsy and intellectual disabilities. It compromises cerebral microcirculation, resulting in insufficient oxygen or blood flow to the periventricular region of the brain. As widely documented, these pathological conditions can be caused by several factors encompassing preterm birth (4-5% of the total cases), as well single cotwin abortion and genetic variants such as those associated with GTPase pathways. Whole exome sequencing (WES) analysis identified a de novo causative variant within the pleckstrin homology domain-containing family G member 1 (PLEKHG1) gene in a patient presenting with PVL. The PLEKHG1 gene is ubiquitously expressed, showing high expression patterns in brain tissues. PLEKHG1 is part of a family of Rho guanine nucleotide exchange factors, and the protein is essential for cell division control protein 42 (CDC42) activation in the GTPase pathway. CDC42 is a key small GTPase of the Rho-subfamily, regulating various cellular functions such as cell morphology, migration, endocytosis, and cell cycle progression. The molecular mechanism involving PLEKHG1 and CDC42 has an intriguing role in the reorientation of cells in the vascular endothelium, thus suggesting that disruption responses to mechanical stress in endothelial cells may be involved in the formation of white matter lesions. Significantly, CDC42 association with white matter abnormalities is underscored by its MIM phenotype number. In contrast, although PLEKHG1 has been recently associated with patients showing white matter hyperintensities, it currently lacks a MIM phenotype number. Additionally, in silico analyses classified the identified variant as pathogenic. Although the patient was born prematurely and subsequently to dichorionic gestation, during which its cotwin died, we suggest that the variant described can strongly contribute to PVL. The aim of the current study is to establish a plausible association between the PLEKHG1 gene and PVL.

Increasing the tumour targeting of antitumour drugs through anlotinib-mediated modulation of the extracellular matrix and the RhoA/ROCK signalling pathway

Anlotinib has strong antiangiogenic effects and leads to vessel normalization. However, the "window period" characteristic in regulating vessel normalization by anlotinib cannot fully explain the long-term survival benefits achieved through combining it with other drugs. In this study, through RNA sequencing (RNA-seq) and label-free quantitative proteomics analysis, we discovered that anlotinib regulated the expression of components of the extracellular matrix (ECM), leading to a significant reduction in ECM stiffness. Our bioinformatic analysis revealed a potential positive relationship between the ECM pathway and gefitinib resistance, poor treatment outcomes for programmed death 1 (PD-1) targeting, and unfavourable prognosis following chemotherapy in lung cancer patients. We administered anlotinib in combination with these antitumour drugs and visualized their distribution using fluorescent labelling in various tumour types. Notably, our results demonstrated that anlotinib prolonged the retention time and distribution of antitumour drugs at the tumour site. Moreover, the combination therapy induced notable loosening of the tumour tissue structure. This reduction was associated with decreased interstitial fluid pressure and tumour solid pressure. Additionally, we observed that anlotinib effectively suppressed the Ras homologue family member A (RhoA)/Rho-associated protein kinase (ROCK) signalling pathway. These findings suggest that, in addition to its antiangiogenic and vessel normalization effects, anlotinib can increase the distribution and retention of antitumour drugs in tumours by modulating ECM expression and physical properties through the RhoA/ROCK signalling pathway. These valuable insights contribute to the development of combination therapies aimed at improving tumour targeting in cancer treatment.

Exercise Attenuate Diaphragm Atrophy in COPD Mice via Inhibiting the RhoA/ROCK Signaling

Background

Exercise is an indispensable component of pulmonary rehabilitation with strong anti-inflammatory effects. However, the mechanisms by which exercise prevents diaphragmatic atrophy in COPD (chronic obstructive pulmonary disease) remain unclear.

Methods

Forty male C57BL/6 mice were assigned to the control (n=16) and smoke (n=24) groups. Mice in the smoke group were exposed to the cigarette smoke (CS) for six months. They were then divided into model and exercise training groups for 2 months. Histological changes were observed in lung and diaphragms. Subsequently, agonist U46639 and antagonist Y27632 of RhoA/ROCK were subjected to mechanical stretching in LPS-treated C2C12 myoblasts. The expression levels of Atrogin-1, MuRF-1, MyoD, Myf5, IL-1β, TNF-α, and RhoA/ROCK were determined by Western blotting.

Results

Diaphragmatic atrophy and increased RhoA/ROCK expression were observed in COPD mice. Exercise training attenuated diaphragmatic atrophy, decreased the expression of MuRF-1, and increased MyoD expression in COPD diaphragms. Exercise also affects the upregulation of RhoA/ROCK and inflammation-related proteins. In in vitro experiments with C2C12 myoblasts, LPS remarkably increased the level of inflammation and protein degradation, whereas Y27632 or combined with mechanical stretching prevented this phenomenon considerably.

Conclusion

RhoA/ROCK plays an important role in the prevention of diaphragmatic atrophy in COPD.

Augmentation of functional recovery via ROCK/PI3K/AKT pathway by Fasudil Hydrochloride in a rat sciatic nerve transection model

Backgrounds

The functional recovery after peripheral nerve injury remains unsatisfactory. This study aims to perform a comprehensive evaluation of the efficacy of Fasudil Hydrochloride at treating the sciatic nerve transection injury in rats and the mechanism involved.

Materials and methods

In animal experiments, 75 Sprague Dawley rats that underwent transection and repair of the right sciatic nerve were divided into a control, Fasudil, and Fas + LY group, receiving daily intraperitoneal injection of saline, Fasudil Hydrochloride (10 mg/kg), and Fasudil Hydrochloride plus LY294002 (5 mg/kg), respectively. At day 3 after surgery, the expression of ROCK2, p-PI3K, and p-AKT in L4-5 DRG and the lumbosacral enlargement was determined using Western blotting. At day 7 and 14, axon density in the distal stump was evaluated with immunostaining using the anti-Neurofilament-200 antibody. At day 30, retrograde tracing by injecting Fluoro-gold in the distal stump was performed. Three months after surgery, remyelination was analyzed with immostaining using the anti-MPZ antibody and the transmission electron microscope; Moreover, Motion-Evoked Potential, and recovery of sensorimotor functions was evaluated with a neuromonitor, Footprint, Hot Plate and Von Frey Filaments, respectively. Moveover, the Gastrocnemius muscles were weighed, and then underwent H＆E staining, and staining of the neuromuscular junction using α-Bungarotoxin to evaluate the extent of atrophy and degeneration of the endplates in the Gastrocnemius. In vitro, spinal motor neurons (SMNs) and dorsal root ganglia (DRG) were cultured to examine the impact of Fasudil Hydrochloride and LY294002 on the axon outgrowth.

Results

Three days after injury, the expression of ROCK2 increased significantly (P＜0.01), and Fasudil application significantly increased the expression of p-PI3K and p-AKT in L4-6 DRG and the lumbosacral enlargement (P < 0.05). At day 7 and 14 after surgery, a higher axon density could be observed in the Fasudil group(P < 0.05). At day 30 after surgery, a larger number of motor and sensory neurons absorbing Fluoro-gold could be observed in the Fasudil group (P < 0.01) Three months after surgery, a greater thickness of myelin sheath could be observed in the Fasudil group (P < 0.05). The electrophysiological test showed that a larger amplitude of motion-evoked potential could be triggered in the Fasudil group (P < 0.01). Behavioral tests showed that a higher sciatic function index and a lower threshold for reacting to heat and mechanical stimuli could be measured in the Fasudil group. (P < 0.01). The wet weight ratio of the Gastrocnemius muscles and the area of the cross section of its myofibrils were greater in the Fasudil group (P < 0.01), which also demonstrated a higer ratio of axon-endplate connection and a larger size of endplates (P < 0.05). And there were no significant differences for the abovementioned parameters between the control and Fas + LY groups (P＞0.05). In vitro studies showed that Fasudil could significantly promote axon growth in DRG and SMNs, and increase the expression of p-PI3K and p-AKT, which could be abolished by LY294002 (P < 0.05).

Conclusions

Fasudil can augment axon regeneration and remyelination, and functional recovery after sciatic nerve injury by activating the PI3K/AKT pathway.

The translational potential of this article

The translation potential of this article is that we report for the first time that Fasudil Hydrochloride has a remarkable efficacy at improving axon regeneration and remyelination following a transection injury of the right sciatic nerve in rats through the ROCK/PI3K/AKT pathway, which has a translational potential to be used clinically to treat peripheral nerve injury.

Dynamic light-responsive RhoA activity regulates mechanosensitive stem cell fate decision in 3D matrices

The behavior of stem cells is regulated by mechanical cues in their niche that continuously vary due to extracellular matrix (ECM) remodeling, pulsated mechanical stress exerted by blood flow, and/or cell migration. However, it is still unclear how dynamics of mechanical cues influence stem cell lineage commitment, especially in a 3D microenvironment where mechanosensing differs from that in a 2D microenvironment. In the present study, we investigated how temporally varying mechanical signaling regulates expression of the early growth response 1 gene (Egr1), which we recently discovered to be a 3D matrix-specific mediator of mechanosensitive neural stem cell (NSC) lineage commitment. Specifically, we temporally controlled the activity of Ras homolog family member A (RhoA), which is known to have a central role in mechanotransduction, using our previously developed Arabidopsis thaliana cryptochrome-2-based optoactivation system. Interestingly, pulsed RhoA activation induced Egr1 upregulation in stiff 3D gels only, whereas static light stimulation induced an increase in Egr1 expression across a wide range of 3D gel stiffnesses. Actin assembly inhibition limited Egr1 upregulation upon RhoA activation, implying that RhoA signaling requires an actin-involved process to upregulate Egr1. Consistently, static-light RhoA activation rather than pulsed-light activation restricted neurogenesis in soft gels. Our findings indicate that the dynamics of RhoA activation influence Egr1-mediated stem cell fate within 3D matrices in a matrix stiffness-dependent manner.

A low androgen state impairs erectile function by suppressing EPAC1 in rat penile corpus cavernosum

Background

Exchange proteins activated by cAMP 1 (EPAC1) can promote vasodilatation by regulating endothelial nitric oxide synthase (eNOS) activity through the phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathway and prevent vascular smooth muscle contraction by restraining the ras homolog gene family, member A/Rho-associated coiled-coil forming protein kinase (RhoA/ROCK) pathway. However, the relationship among EPAC1, androgen and erectile function is still unknown. Therefore, we attempted to investigate whether EPAC1 expresses in penile corpus cavernosum of rats and how EPAC1 affects erectile function under low androgenic conditions.

Methods

Thirty 8-week-old Sprague-Dawley male rats were randomly divided into six groups (n=5): sham operation (sham), castrated, castrated + testosterone replacement (castrated + T), sham + EPAC1 over-expression lentivirus (sham + EPAC1), castrated + empty lentivirus vector (castrated + empty vector), and castrated + EPAC1. Four weeks after the operation, the lentivirus vectors carrying the EPAC1 gene were injected into the penile corpus cavernosum of the sham + EPAC1 and castrated + EPAC1 groups (1×108 TU/mL, 20 µL per rat). A week after injection, the ratio of maximum intracavernous pressure to mean arterial pressure (ICPmax/MAP) and the levels of serum testosterone (T), nitric oxide (NO), the active form of RhoA (RhoA-GTP), AKT, phospho-AKT (p-AKT), eNOS, phospho-eNOS (p-eNOS), p-AKT/AKT, p-eNOS/eNOS and EPAC1 levels were measured.

Results

In comparison to the sham group, ICPmax/MAP and EPAC1 content in the castrated group were significantly reduced. EPAC1 is primarily located in the cyto-membrane and cytoplasm of endothelial cells and smooth muscle cells in the rat penile corpus cavernosum. In comparison to the sham group, the T, ICPmax/MAP and NO levels of the castrated group were significantly reduced (P<0.01). Meanwhile, the RhoA-GTP concentration in the castrated + EPAC1 group was reduced in comparison with the castrated + empty vector group (P<0.01). Compared with the castrated + empty vector group, the p-AKT/AKT, EPAC1 and p-eNOS/eNOS levels in the castrated + EPAC1 group were significantly increased (P<0.05).

Conclusions

Androgen deficiency can suppress EPAC1 expression in the penile corpus cavernosum of rats, while the up-regulation of which can improve the erectile function of castrated rats.

Soluble TREM2 ameliorates tau phosphorylation and cognitive deficits through activating transgelin-2 in Alzheimer's disease

Triggering receptor expressed on myeloid cells 2 (TREM2) is a transmembrane protein that is predominantly expressed by microglia in the brain. The proteolytic shedding of TREM2 results in the release of soluble TREM2 (sTREM2), which is increased in the cerebrospinal fluid of patients with Alzheimer's disease (AD). It remains unknown whether sTREM2 regulates the pathogenesis of AD. Here we identified transgelin-2 (TG2) expressed on neurons as the receptor for sTREM2. The microglia-derived sTREM2 binds to TG2, induces RhoA phosphorylation at S188, and deactivates the RhoA-ROCK-GSK3β pathway, ameliorating tau phosphorylation. The sTREM2 (77-89) fragment, which is the minimal active sequence of sTREM2 to activate TG2, mimics the inhibitory effect of sTREM2 on tau phosphorylation. Overexpression of sTREM2 or administration of the active peptide rescues tau pathology and behavioral defects in the tau P301S transgenic mice. Together, these findings demonstrate that the sTREM2-TG2 interaction mediates the cross-talk between microglia and neurons. sTREM2 and its active peptide may be a potential therapeutic intervention for tauopathies including AD.

Mechanistic Regulation of Wnt Pathway-Related Progression of Chronic Obstructive Pulmonary Disease Airway Lesions

Chronic obstructive pulmonary disease (COPD) is a chronic disease associated with inflammation and structural changes in the airways and lungs, resulting from a combination of genetic and environmental factors. This interaction highlights significant genes in early life, particularly those involved in lung development, such as the Wnt signaling pathway. The Wnt signaling pathway plays an important role in cell homeostasis, and its abnormal activation can lead to the occurrence of related diseases such as asthma, COPD, and lung cancer. Due to the fact that the Wnt pathway is mechanically sensitive, abnormal activation of the Wnt pathway by mechanical stress contributes to the progression of chronic diseases. But in the context of COPD, it has received little attention. In this review, we aim to summarize the important current evidence on mechanical stress through the Wnt pathway in airway inflammation and structural changes in COPD and to provide potential targets for COPD treatment strategies.

The Dual Function of RhoGDI2 in Immunity and Cancer

RhoGDI2 is a guanine nucleotide dissociation inhibitor (GDI) specific for the Rho family of small GTPases. It is highly expressed in hematopoietic cells but is also present in a large array of other cell types. RhoGDI2 has been implicated in multiple human cancers and immunity regulation, where it can display a dual role. Despite its involvement in various biological processes, we still do not have a clear understanding of its mechanistic functions. This review sheds a light on the dual opposite role of RhoGDI2 in cancer, highlights its underappreciated role in immunity and proposes ways to explain its intricate regulatory functions.

Dysregulation of miR-193a serves as a potential contributor to MS pathogenesis via affecting RhoA and Rock1

BACKGROUND

Multiple sclerosis (MS) is one of the most common neurological diseases that cause chronic inflammation of the central nervous system and demyelination of the myelin sheath. At present, microRNAs (miRNAs) are considered not only a diagnostic and prognostic indicator of diseases but also a new goal in gene therapy. This study aims to find a simple, non-invasive, valuable biomarker for early detection and potential treatment of MS.

METHODS

In the present study, 30 patients with MS were included. The qRT-PCR method was performed to evaluate the expression level of miR-193a, RhoA, and ROCK1. Besides, western blotting was performed to determine the expression level of RhoA and ROCK1 at protein levels. Moreover, we aimed to clarify the possible correlation between miR-193a-5p and its-regulated target genes so that miR-193a-5p mimic was transfected into MS-derived cultured PBMSs, and the expression level of RhoA and ROCK1 were then evaluated by qRT-PCR and Western blotting. In the final step, the correlation between miR-193a-5p and clinicopathological features of patients was investigated.

RESULTS

Results showed that miR-193a was decreased while RhoA and ROCK1 were up-regulated in PBMCs obtained from patients with MS compared to the control group. It was also revealed that miR-193a transfection reduced RhoA and ROCK1 expression at mRNA and protein levels. The results from the Chi-square analysis showed that down-regulation of miR-193a was associated with increased CRP level, CSF IgG positivity, and MSSS (Multiple Sclerosis Severity Score), suggesting miR-193a is a potential diagnostic and prognostic indicator.

CONCLUSION

We implied that miR-193a could modulate RhoA and ROCK 1 expression in MS patients, in which its down-regulation leads to increased expression of RhoA and ROCK1 and poor prognosis of patients with MS. Therefore, miR-193a and its associated targets could serve potential prognostic, diagnostic, and therapeutic efficacy in MS patients.

Remotely Temporal Scheduled Macrophage Phenotypic Transition Enables Optimized Immunomodulatory Bone Regeneration

Precise timing of macrophage polarization plays a pivotal role in immunomodulation of tissue regeneration, yet most studies mainly focus on M2 macrophages for their anti-inflammatory and regenerative effects while the essential proinflammatory role of the M1 phenotype on the early inflammation stage is largely underestimated. Herein, a superparamagnetic hydrogel capable of timely controlling macrophage polarization is constructed by grafting superparamagnetic nanoparticles on collagen nanofibers. The magnetic responsive hydrogel network enables efficient polarization of encapsulated macrophage to the M2 phenotype through the podosome/Rho/ROCK mechanical pathway in response to static magnetic field (MF) as needed. Taking advantage of remote accessibility of magnetic field together with the superparamagnetic hydrogels, a temporal engineered M1 to M2 transition course preserving the essential role of M1 at the early stage of tissue healing, as well as enhancing the prohealing effect of M2 at the middle/late stages is established via delayed MF switch. Such precise timing of macrophage polarization matching the regenerative process of injured tissue eventually leads to optimized immunomodulatory bone healing in vivo. Overall, this study offers a remotely time-scheduled approach for macrophage polarization, which enables precise manipulation of inflammation progression during tissue healing.

Cellular Conditions Responsible for Methylmercury-Mediated Neurotoxicity

Methylmercury (MeHg) is a widely known environmental pollutant that causes severe neurotoxicity. MeHg-induced neurotoxicity depends on various cellular conditions, including differences in the characteristics of tissues and cells, exposure age (fetal, childhood, or adulthood), and exposure levels. Research has highlighted the importance of oxidative stress in the pathogenesis of MeHg-induced toxicity and the site- and cell-specific nature of MeHg-induced neurotoxicity. The cerebellar granule cells and deeper layer cerebrocortical neurons are vulnerable to MeHg. In contrast, the hippocampal neurons are resistant to MeHg, even at high mercury accumulation levels. This review summarizes the mechanisms underlying MeHg-mediated intracellular events that lead to site-specific neurotoxicity. Specifically, we discuss the mechanisms associated with the redox ability, neural outgrowth and synapse formation, cellular signaling pathways, epigenetics, and the inflammatory conditions of microglia.

RhoA Signaling in Neurodegenerative Diseases

Ras homolog gene family member A (RhoA) is a small GTPase of the Rho family involved in regulating multiple signal transduction pathways that influence a diverse range of cellular functions. RhoA and many of its downstream effector proteins are highly expressed in the nervous system, implying an important role for RhoA signaling in neurons and glial cells. Indeed, emerging evidence points toward a role of aberrant RhoA signaling in neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, and amyotrophic lateral sclerosis. In this review, we summarize the current knowledge of RhoA regulation and downstream cellular functions with an emphasis on the role of RhoA signaling in neurodegenerative diseases and the therapeutic potential of RhoA inhibition in neurodegeneration.

Underappreciated roles for Rho GDP dissociation inhibitors (RhoGDIs) in cell function: Lessons learned from the pancreatic islet β-cell

Rho subfamily of G proteins (e.g., Rac1) have been implicated in glucose-stimulated insulin secretion from the pancreatic β-cell. Interestingly, metabolic stress (e.g., chronic exposure to high glucose) results in sustained activation of Rac1 leading to increased oxidative stress, impaired insulin secretion and β-cell dysfunction. Activation-deactivation of Rho G proteins is mediated by three classes of regulatory proteins, namely the guanine nucleotide exchange factors (GEFs), which facilitate the conversion of inactive G proteins to their active conformations; the GTPase-activating proteins (GAPs), which convert the active G proteins to their inactive forms); and the GDP-dissociation inhibitors (GDIs), which prevent the dissociation of GDP from G proteins. Contrary to a large number of GEFs (82 members) and GAPs (69 members), only three members of RhoGDIs (RhoGDIα, RhoGDIβ and RhoGDIγ) are expressed in mammalian cells.Even though relatively smaller in number, the GDIs appear to play essential roles in G protein function (e.g., subcellular targeting) for effector activation and cell regulation. Emerging evidence also suggests that the GDIs are functionally regulated via post-translational modification (e.g., phosphorylation) and by lipid second messengers, lipid kinases and lipid phosphatases. We highlight the underappreciated regulatory roles of RhoGDI-Rho G protein signalome in islet β-cell function in health and metabolic stress. Potential knowledge gaps in the field, and directions for future research for the identification of novel therapeutic targets to loss of functional β-cell mass under the duress of metabolic stress are highlighted.

Oxycodone relieves permeability damage and apoptosis of oxygen-glucose deprivation/reoxygenation-induced brain microvascular endothelial cells through ras homolog family member A (RhoA)/ Rho-associated coiled-coil containing kinases (ROCK)/ myosin light chain 2 (MLC2) signal

Cerebrovascular disease, an important cause of acute ischemic stroke, has attracted worldwide attention. Oxycodone has been widely used to treat various painful disorders. This study was designed to explore the mechanism of oxycodone in oxygen-glucose deprivation/reoxygenation (OGD/R)-induced brain microvascular endothelial cell model. For the reliability of the results in the following experiments, the viability was firstly detected using CCK-8. With the application of LDH, TEER and TUNEL assays, the LDH expression, permeability and apoptosis of brain microvascular endothelial cells were detected, respectively. Besides, the mRNA and protein expressions of tight junction proteins and RhoA were measured using RT-qPCR and Western blot. Moreover, RT-qPCR was employed to evaluate the expressions of inflammatory cytokines. Western blot was adopted to measure the levels of RhoA, ROCK, MLC2 and apoptosis-related proteins. The results revealed that oxycodone attenuated permeability damage, inflammatory factor release and apoptosis of OGD/R-induced brain microvascular endothelial cells in a dose-dependent manner. It was also found that oxycodone could reduce the expressions of RhoA, ROCK and MLC2 in brain microvascular endothelial cells induced by OGD/R. More importantly, oxycodone exhibited desirable effects on OGD/R-induced brain microvascular endothelial cells through RhoA/ROCK/MLC2 signal. In conclusion, oxycodone relieved permeability damage and apoptosis of OGD/R-induced brain microvascular endothelial cells through RhoA/ROCK/MLC2 signal, suggesting that oxycodone might be an effective method for the improvement of cerebral ischemia-reperfusion injury.

Melatonin supplementation in the culture medium rescues impaired glucose metabolism in IVF mice offspring

Increasing evidence suggests that in vitro fertilization (IVF) may be associated with an increased risk of developing obesity and metabolic diseases later in life in the offspring. Notably, the addition of melatonin to culture medium may improve embryo development and prevent cardiovascular dysfunction in IVF adult mice. This study aimed to determine if melatonin supplementation in the culture medium can reverse impaired glucose metabolism in IVF mice offspring and the underlying mechanisms. Blastocysts used for transfer were generated by natural mating (control group) or IVF with or without melatonin (10^-6  M) supplementation (mIVF and IVF group, respectively) in clinical-grade culture media. Here, we first report that IVF decreased hepatic expression of Fbxl7, which was associated with impaired glucose metabolism in mice offspring. Melatonin addition reversed the phenotype by up-regulating the expression of hepatic Fbxl7. In vitro experiments showed that Fbxl7 enhanced the insulin signaling pathway by degrading RhoA through ubiquitination and was up-regulated by transcription factor Foxa2. Specific knockout of Fbxl7 in the liver of adult mice, through tail intravenous injection of recombinant adeno-associated virus, impaired glucose tolerance, while overexpression of hepatic Fbxl7 significantly improved glucose tolerance in adult IVF mice. Thus, the data suggest that Fbxl7 plays an important role in maintaining glucose metabolism of mice, and melatonin supplementation in the culture medium may rescue the long-term risk of metabolic diseases in IVF offspring.

Regulation of transforming growth factor-β signalling by SUMOylation and its role in fibrosis

Fibrosis is an abnormal healing process that only repairs the structure of an organ after injury and does not address damaged functions. The pathogenesis of fibrosis is multifactorial and highly complex; numerous signalling pathways are involved in this process, with the transforming growth factor-β (TGF-β) signalling pathway playing a central role. TGF-β regulates the generation of myofibroblasts and the epithelial-mesenchymal transition by regulating transcription and translation of downstream genes and precisely regulating fibrogenesis. The TGF-β signalling pathway can be modulated by various post-translational modifications, of which SUMOylation has been shown to play a key role. In this review, we focus on the function of SUMOylation in canonical and non-canonical TGF-β signalling and its role in fibrosis, providing promising therapeutic strategies for fibrosis.

Neurotrophins as Key Regulators of Cell Metabolism: Implications for Cholesterol Homeostasis

Neurotrophins constitute a family of growth factors initially characterized as predominant mediators of nervous system development, neuronal survival, regeneration and plasticity. Their biological activity is promoted by the binding of two different types of receptors, leading to the generation of multiple and variegated signaling cascades in the target cells. Increasing evidence indicates that neurotrophins are also emerging as crucial regulators of metabolic processes in both neuronal and non-neuronal cells. In this context, it has been reported that neurotrophins affect redox balance, autophagy, glucose homeostasis and energy expenditure. Additionally, the trophic support provided by these secreted factors may involve the regulation of cholesterol metabolism. In this review, we examine the neurotrophins' signaling pathways and their effects on metabolism by critically discussing the most up-to-date information. In particular, we gather experimental evidence demonstrating the impact of these growth factors on cholesterol metabolism.

Intravenous infusion of bone marrow mononuclear cells promotes functional recovery and improves impaired cognitive function via inhibition of Rho guanine nucleotide triphosphatases and inflammatory signals in a model of chronic epilepsy

Temporal lobe epilepsy is the most common form of intractable epilepsy in adults. More than 30% of individuals with epilepsy have persistent seizures and have drug-resistant epilepsy. Based on our previous findings, treatment with bone marrow mononuclear cells (BMMC) could interfere with early and chronic phase epilepsy in rats and in clinical settings. In this pilocarpine-induced epilepsy model, animals were randomly assigned to two groups: control (Con) and epileptic pre-treatment (Ep-pre-t). The latter had status epilepticus (SE) induced through pilocarpine intraperitoneal injection. Later, seizure frequency was assessed using a video-monitoring system. Ep-pre-t was further divided into epileptic treated with saline (Ep-Veh) and epileptic treated with BMMC (Ep-BMMC) after an intravenous treatment with BMMC was done on day 22 after SE. Analysis of neurobehavioral parameters revealed that Ep-BMMC had significantly lower frequency of spontaneous recurrent seizures (SRS) in comparison to Ep-pre-t and Ep-Veh groups. Hippocampus-dependent spatial and non-spatial learning and memory were markedly impaired in epileptic rats, a deficit that was robustly recovered by treatment with BMMC. Moreover, long-term potentiation-induced synaptic remodeling present in epileptic rats was restored by BMMC. In addition, BMMC was able to reduce abnormal mossy fiber sprouting in the dentate gyrus. Molecular analysis in hippocampal tissue revealed that BMMC treatment down-regulates the release of inflammatory cytokine tumor necrosis factor-α (TNF-α) and Allograft inflammatory factor-1 (AIF-1) as well as the Rho subfamily of small GTPases [Ras homolog gene family member A (RhoA) and Ras-related C3 botulinum toxin substrate 1 (Rac)]. Collectively, delayed BMMC treatment showed positive effects when intravenously infused into chronic epileptic rats.

Distinct dual roles of p-Tyr42 RhoA GTPase in tau phosphorylation and ATP citrate lyase activation upon different Aβ concentrations

Both the accumulation of Amyloid-β (Aβ) in plaques and phosphorylation of Tau protein (p-Tau) in neurofibrillary tangles have been identified as two major symptomatic features of Alzheimer's disease (AD). Despite of critical role of Aβ and p-Tau in AD progress, the interconnection of signalling pathways that Aβ induces p-Tau remains elusive. Herein, we observed that a popular AD model mouse (APP/PS1) and Aβ-injected mouse showed an increase in p-Tyr42 Rho in hippocampus of brain. Low concentrations of Aβ (1 μM) induced RhoA-mediated Ser422 phosphorylation of Tau protein (p-Ser422 Tau), but reduced the expression of ATP citrate lyase (ACL) in the HT22 hippocampal neuronal cell line. In contrast, high concentrations of Aβ (10 μM) along with high levels of superoxide production remarkably attenuated accumulation of p-Ser422 Tau, but augmented ACL expression and activated sterol regulatory element-binding protein 1 (SREBP1), leading to cellular senescence. Notably, a high concentration of Aβ (10 μM) induced nuclear localization of p-Tyr42 Rho, which positively regulated NAD kinase (NADK) expression by binding to the NADK promoter. Furthermore, severe AD patient brain showed high p-Tyr42 Rho levels. Collectively, our findings indicate that both high and low concentrations of Aβ are detrimental to neurons via distinct two p-Tyr42 RhoA-mediated signalling pathways in Ser422 phosphorylation of Tau and ACL expression.

RhoA/ROCK Regulates Prion Pathogenesis by Controlling Connexin 43 Activity

Scrapie infection, which converts cellular prion protein (PrP^C) into the pathological and infectious isoform (PrP^Sc), leads to neuronal cell death, glial cell activation and PrP^Sc accumulation. Previous studies reported that PrP^C regulates RhoA/Rho-associated kinase (ROCK) signaling and that connexin 43 (Cx43) expression is upregulated in in vitro and in vivo prion-infected models. However, whether there is a link between RhoA/ROCK and Cx43 in prion disease pathogenesis is uncertain. Here, we investigated the role of RhoA/ROCK signaling and Cx43 in prion diseases using in vitro and in vivo models. Scrapie infection induced RhoA activation, accompanied by increased phosphorylation of LIM kinase 1/2 (LIMK1/2) at Thr508/Thr505 and cofilin at Ser3 and reduced phosphorylation of RhoA at Ser188 in hippocampal neuronal cells and brains of mice. Scrapie infection-induced RhoA activation also resulted in PrP^Sc accumulation followed by a reduction in the interaction between RhoA and p190RhoGAP (a GTPase-activating protein). Interestingly, scrapie infection significantly enhanced the interaction between RhoA and Cx43. Moreover, RhoA and Cx43 colocalization was more visible in both the membrane and cytoplasm of scrapie-infected hippocampal neuronal cells than in controls. Finally, RhoA and ROCK inhibition reduced PrP^Sc accumulation and the RhoA/Cx43 interaction, leading to decreased Cx43 hemichannel activity in scrapie-infected hippocampal neuronal cells. These findings suggest that RhoA/ROCK regulates Cx43 activity, which may have an important role in the pathogenesis of prion disease.

Lupeol inhibits migration and invasion of colorectal cancer cells by suppressing RhoA-ROCK1 signaling pathway

Metastasis is the main cause of death in colorectal cancer (CRC) patients. However, current treatment options for CRC metastasis are very limited. Lupeol, a triterpene that is widely found in vegetables and fruits, has been reported to possess the cancer-preventive and anti-inflammatory functions. However, the roles of Lupeol in the migration and invasion of colorectal cancer remain unclear. Here, we evaluated the effect of Lupeol treatment on colorectal cancer cell lines, HCT116 and SW620, and delineated its underlying mechanisms. Our results showed that Lupeol induced a dose-dependent inhibition of HCT116 and SW620 cells viability, measured by CCK8 assay. Wound healing and Transwell migration and invasion assays revealed that Lupeol significantly suppressed the migration and invasion of CRC cells. Using laser confocal microscope, we observed that the pseudopods and protrusions of HCT116 and SW620 cells decreased and disrupted after treatment with Lupeol. In addition, the quantitative real-time PCR and Western blotting results showed that Lupeol downregulated the expression of RhoA and RhoC, and their downstream effectors ROCK1, Cofilin, p-MLC, and the associated regulatory protein Cyclin A2. Interestingly, the migration and invasion capacity of CRC cells was reduced after RhoA knockdown. And there were no additional changes in CRC cells with RhoA knockdown to treat with Lupeol. These findings demonstrate that Lupeol can suppress the migration and invasion of colorectal cancer cells by remodeling the actin cytoskeleton via RhoA-ROCK1 pathway inhibition, which may provide an effective anti-metastatic agent for CRC patients.

PM2.5, Fine Particulate Matter: A Novel Player in the Epithelial-Mesenchymal Transition?

Epithelial-mesenchymal transition (EMT) refers to the conversion of epithelial cells to mesenchymal phenotype, which endows the epithelial cells with enhanced migration, invasion, and extracellular matrix production abilities. These characteristics link EMT with the pathogenesis of organ fibrosis and cancer progression. Recent studies have preliminarily established that fine particulate matter with an aerodynamic diameter of less than 2.5 μm (PM_2.5) is correlated with EMT initiation. In this pathological process, PM_2.5 particles, excessive reactive oxygen species (ROS) derived from PM_2.5, and certain components in PM_2.5, such as ions and polyaromatic hydrocarbons (PAHs), have been implicated as potential EMT mediators that are linked to the activation of transforming growth factor β (TGF-β)/SMADs, NF-κB, growth factor (GF)/extracellular signal-regulated protein kinase (ERK), GF/phosphatidylinositol 3-kinase (PI3K)/Akt, wingless/integrated (Wnt)/β-catenin, Notch, Hedgehog, high mobility group box B1 (HMGB1)-receptor for advanced glycation end-products (RAGE), and aryl hydrocarbon receptor (AHR) signaling cascades and to cytoskeleton rearrangement. These pathways directly and indirectly transduce pro-EMT signals that regulate EMT-related gene expression in epithelial cells, finally inducing the characteristic alterations in morphology and functions of epithelia. In addition, novel associations between autophagy, ATP citrate lyase (ACLY), and exosomes with PM_2.5-induced EMT have also been summarized. However, some debates and paradoxes remain to be consolidated. This review discusses the potential molecular mechanisms underlying PM_2.5-induced EMT, which might account for the latent role of PM_2.5 in cancer progression and fibrogenesis.