Rho GTPase activity crosstalk mediated by Arhgef11 and Arhgef12 coordinates cell protrusion-retraction cycles

Activation of G protein-coupled estrogen receptor alleviates the abnormal changes of synaptic plasticity in the anterior insula of temporal lobe epilepsy rats through RhoA/Rock2 pathway

Temporal lobe epilepsy (TLE) is the most common type of refractory epilepsy, characterized by highly synchronized abnormal neuronal discharge. The insula cortex (IC) serves as a key "node" in the TLE transmission network, and the anterior insula (AI) is a critical gatekeeper to executive control; however, the pathological changes of the IC/AI have been overlooked. GPER1 is a G protein coupled estrogen receptor anchored by PSD95 to the plasma membrane of dendritic spine (DS), participating in the regulation of DS plasticity. We found that Gper1 deletion rats exhibited increased susceptibility to epilepsy, but it remains unclear whether and how GPER1 regulates alterations in DS plasticity in the IC after TLE induction. Here, we observed that the interaction between GPER1 and PSD95 diminished at TLE induction 7 d, the dendrite complexity and DS density were altered in the AI. While, activating of GPER1 ameliorated the neuronal damage and loss in the AI of TLE rats, decreased dendrite complexity and increased DS density，enhanced the interaction between GPER1 and PSD95, then mitigated the inhibition of Rock2 and its downstream targets, cofilin and the imbalance of F/G-actin, which was induced by the over-activation of CAMKII and RhoA. Thus, improved the emotion and cognitive dysfunction of TLE rats. Our results offer compelling evidence for elucidating the mechanism of abnormal changes in insular synaptic plasticity following TLE and the selection of therapeutic targets.

The experimental study of the effect of fluid shear force on the migration rate of human umbilical vein endothelial cells

BACKGROUND

The vascular endothelium is a continuous monolayer of flattened cells that cover the surface of the lumen of blood vessels. Endothelial cell damage can readily result in thrombus formation and thickening of the intima. Accelerating the migration and repair of peripheral endothelial cells is essential. Shear force is an important hydrodynamic factor affecting endothelial cell function. We aimed to investigate the effect of different shear forces on the migration rate of endothelial cells.

METHODS

Human umbilical vein endothelial cells (HUVECs) were used instead of endothelial cells to establish a cell scratch model. Plate flow chambers were then used to intervene in HUVECs growth with different shear force magnitudes (4 dyn/cm2, 8 dyn/cm2, and 12 dyn/cm2). The healing rate of the scratches was observed under light microscopy, and finally the expression of RhoA and CDC42 was detected by molecular experiments. The expression of CDC42 factor was inhibited by siRNA interference, and the wound healing ability of HUVECs in the control group and the CDC42 inhibition group under different fluid shear forces was observed under light microscopy.

RESULTS

High shear forces promote the healing of scratches. In addition, relatively strong shear forces promoted the expression of cytokines RhoA and CDC42. Compared with untransfected HUVECs, HUVECs with inhibition of CDC42 expression by siRNA interference showed weak migration ability in different fluid shear groups.

CONCLUSION

Increasing fluid shear force in a range (4-12 dyn/cm2) contributes to endothelial cell migration. Inhibition of CDC42 expression weakened the migration ability of HUVECs under different fluid shear forces.

The causal effects of 2,821 protein level ratios on non-small cell lung cancer: a two-sample Mendelian randomization study

Background

Non-small cell lung cancer (NSCLC) has a complex etiology, making early diagnosis difficult and leading to high mortality rates, thus necessitating personalized treatment strategies. While protein level ratios have shown potential as biomarkers or therapeutic targets, their causal relationship with NSCLC remains unclear. This study aimed to investigate these causal links using Mendelian randomization (MR), providing insights into potential biomarkers and therapeutic avenues.

Methods

We executed an intricate two-sample MR study to explore the stochastic causal links between 2,821 protein level ratios and NSCLC. The genome-wide association study (GWAS) statistics for NSCLC and protein level ratios were sourced from the Finnish Database (version 10) and the UK Biobank, respectively. For the instrumental variables (IVs) related to protein level ratios, we selected IVs with a P value <1.0×10-5. Throughout this analysis, we applied five established MR techniques.

Results

Our study identified causal relationships between 142 protein level ratios and NSCLC. Notably, the AKR1B1/SUGT1 protein level ratio and the PLPBP/STIP1 protein level ratio demonstrated the most significant negative correlations with NSCLC risk. On the other hand, the ARHGEF12/IRAK4 protein level ratio and the BANK1/LBR protein level ratio exhibited the most significant positive correlations. Furthermore, sensitivity analyses did not reveal any significant heterogeneity or horizontal pleiotropy.

Conclusions

Studying specific protein level ratios in patients can reveal the molecular mechanisms and pathological processes of NSCLC, which has certain clinical significance for early diagnosis of NSCLC, understanding drug resistance mechanisms and developing personalized treatment strategies. However, these findings necessitate further validation through extensive clinical research.

Tumor microtubes: A new potential therapeutic target for high-grade gliomas

High-grade infiltrating gliomas are highly aggressive and fatal brain tumors that present significant challenges for research and treatment due to their complex microenvironment and tissue structure. Recent discovery of tumor microtubes (TMs) has provided new insights into how high-grade gliomas develop in the brain and resist treatment. TMs are unique, ultra-long, and highly functional membrane protrusions that form multicellular networks and play crucial roles in glioma invasiveness, drug resistance, recurrence, and heterogeneity. This review focuses on the different roles that TMs play in glioma cell communication, material transport, and tumor cell behavior. Specifically, non-connecting TMs primarily promote glioma invasiveness, likely related to their role in enhancing cell motility. On the other hand, interconnecting TMs form functional and communication networks by connecting with surrounding astrocytes and neurons, thereby promoting glioma malignancy. We summarize the factors that influence the formation of TMs in gliomas and current strategies targeting TMs. As the understanding of TMs advances, we are closer to uncovering whether they might be the long-sought Achilles' heel of treatment-resistant gliomas. By delving deeper into TMs research, we hope to develop more effective therapeutic strategies for patients with malignant gliomas.

Bacterial toxins induce non-canonical migracytosis to aggravate acute inflammation

Migracytosis is a recently described cellular process that generates and releases membrane-bound pomegranate-like organelles called migrasomes. Migracytosis normally occurs during cell migration, participating in various intercellular biological functions. Here, we report a new type of migracytosis induced by small GTPase-targeting toxins. Unlike classic migracytosis, toxin-induced migrasome formation does not rely on cell migration and thus can occur in both mobile and immobile cells. Such non-canonical migracytosis allows the cells to promptly respond to microbial stimuli such as bacterial toxins and effectors and release informative cellular contents in bulk. We demonstrated that C. difficile TcdB3 induces liver endothelial cells and Kupffer cells to produce migrasomes in vivo. Moreover, the migracytosis-defective Tspan9‒/‒ mice show less acute inflammation and lower lethality rate in the toxin challenge assay. Therefore, we propose that the non-canonical migracytosis acts as a new mechanism for mammalian species to sense and exacerbate early immune response upon microbial infections.

Light-guided actin polymerization drives directed motility in protocells

Motility is a hallmark of life's dynamic processes, enabling cells to actively chase prey, repair wounds, and shape organs. Recreating these intricate behaviors using well-defined molecules remains a major challenge at the intersection of biology, physics, and molecular engineering. Although the polymerization force of the actin cytoskeleton is characterized as a primary driver of cell motility, recapitulating this process in protocellular systems has proven elusive. The difficulty lies in the daunting task of distilling key components from motile cells and integrating them into model membranes in a physiologically relevant manner. To address this, we developed a method to optically control actin polymerization with high spatiotemporal precision within cell-mimetic lipid vesicles known as giant unilamellar vesicles (GUVs). Within these active protocells, the reorganization of actin networks triggered outward membrane extensions as well as the unidirectional movement of GUVs at speeds of up to 0.43 μm/min, comparable to typical adherent mammalian cells. Notably, our findings reveal a synergistic interplay between branched and linear actin forms in promoting membrane protrusions, highlighting the cooperative nature of these cytoskeletal elements. This approach offers a powerful platform for unraveling the intricacies of cell migration, designing synthetic cells with active morphodynamics, and advancing bioengineering applications, such as self-propelled delivery systems and autonomous tissue-like materials.

Excitable Rho dynamics control cell shape and motility by sequentially activating ERM proteins and actomyosin contractility

Migration of endothelial and many other cells requires spatiotemporal regulation of protrusive and contractile cytoskeletal rearrangements that drive local cell shape changes. Unexpectedly, the small GTPase Rho, a crucial regulator of cell movement, has been reported to be active in both local cell protrusions and retractions, raising the question of how Rho activity can coordinate cell migration. Here, we show that Rho activity is absent in local protrusions and active during retractions. During retractions, Rho rapidly activated ezrin-radixin-moesin proteins (ERMs) to increase actin-membrane attachment, and, with a delay, nonmuscle myosin 2 (NM2). Rho activity was excitable, with NM2 acting as a slow negative feedback regulator. Strikingly, inhibition of SLK/LOK kinases, through which Rho activates ERMs, caused elongated cell morphologies, impaired Rho-induced cell contractions, and reverted Rho-induced blebbing. Together, our study demonstrates that Rho activity drives retractions by sequentially enhancing ERM-mediated actin-membrane attachment for force transmission and NM2-dependent contractility.

Patterning of the cell cortex by Rho GTPases

The Rho GTPases - RHOA, RAC1 and CDC42 - are small GTP binding proteins that regulate basic biological processes such as cell locomotion, cell division and morphogenesis by promoting cytoskeleton-based changes in the cell cortex. This regulation results from active (GTP-bound) Rho GTPases stimulating target proteins that, in turn, promote actin assembly and myosin 2-based contraction to organize the cortex. This basic regulatory scheme, well supported by in vitro studies, led to the natural assumption that Rho GTPases function in vivo in an essentially linear matter, with a given process being initiated by GTPase activation and terminated by GTPase inactivation. However, a growing body of evidence based on live cell imaging, modelling and experimental manipulation indicates that Rho GTPase activation and inactivation are often tightly coupled in space and time via signalling circuits and networks based on positive and negative feedback. In this Review, we present and discuss this evidence, and we address one of the fundamental consequences of coupled activation and inactivation: the ability of the Rho GTPases to self-organize, that is, direct their own transition from states of low order to states of high order. We discuss how Rho GTPase self-organization results in the formation of diverse spatiotemporal cortical patterns such as static clusters, oscillatory pulses, travelling wave trains and ring-like waves. Finally, we discuss the advantages of Rho GTPase self-organization and pattern formation for cell function.