Small chemical compounds Y16 and Rhosin can inhibit calcium sensitization pathway in vascular smooth muscle cells of spontaneously hypertensive rats

Molecular profiling of sponge deflation reveals an ancient relaxant-inflammatory response

A hallmark of animals is the coordination of whole-body movement. Neurons and muscles are central to this, yet coordinated movements also exist in sponges that lack these cell types. Sponges are sessile animals with a complex canal system for filter-feeding. They undergo whole-body movements resembling "contractions" that lead to canal closure and water expulsion. Here, we combine live 3D optical coherence microscopy, pharmacology, and functional proteomics to elucidate the sequence and detail of shape changes, the tissues and molecular physiology involved, and the control of these movements. Morphometric analysis and targeted perturbation suggest that the movement is driven by the relaxation of actomyosin stress fibers in epithelial canal cells, which leads to whole-body deflation via collapse of the incurrent and expansion of the excurrent canal system. Thermal proteome profiling and quantitative phosphoproteomics confirm the control of cellular relaxation by an Akt/NO/PKG/PKA pathway. Agitation-induced deflation leads to differential phosphorylation of proteins forming epithelial cell junctions, implying their mechanosensitive role. Unexpectedly, untargeted metabolomics detect a concomitant decrease in antioxidant molecules during deflation, reflecting an increase in reactive oxygen species. Together with the secretion of proteinases, cytokines, and granulin, this indicates an inflammation-like state of the deflating sponge reminiscent of vascular endothelial cells experiencing oscillatory shear stress. These results suggest the conservation of an ancient relaxant-inflammatory response of perturbed fluid-carrying systems in animals and offer a possible mechanism for whole-body coordination through diffusible paracrine signals and mechanotransduction.

Molecular profiling of sponge deflation reveals an ancient relaxant-inflammatory response

A hallmark of animals is the coordination of whole-body movement. Neurons and muscles are central to this, yet coordinated movements also exist in sponges that lack these cell types. Sponges are sessile animals with a complex canal system for filter-feeding. They undergo whole-body movements resembling "contractions" that lead to canal closure and water expulsion. Here, we combine 3D optical coherence microscopy, pharmacology, and functional proteomics to elucidate anatomy, molecular physiology, and control of these movements. We find them driven by the relaxation of actomyosin stress fibers in epithelial canal cells, which leads to whole-body deflation via collapse of the incurrent and expansion of the excurrent system, controlled by an Akt/NO/PKG/A pathway. A concomitant increase in reactive oxygen species and secretion of proteinases and cytokines indicate an inflammation-like state reminiscent of vascular endothelial cells experiencing oscillatory shear stress. This suggests an ancient relaxant-inflammatory response of perturbed fluid-carrying systems in animals.

Small GTPase control of pituitary hormone secretion: Evidence from studies in the goldfish (Carassius auratus) neuroendocrine model

The secretion of vertebrate pituitary hormones is regulated by multiple hypothalamic factors, which, while generally activating unique receptor systems, ultimately propagate signals through interacting intracellular regulatory elements to modulate hormone exocytosis. One important family of intracellular regulators is the monomeric small GTPases, a subset of which (Arf1/6, Rac, RhoA, and Ras) is highly conserved across vertebrates and regulates secretory vesicle exocytosis in many cell types. In this study, we investigated the roles of these small GTPases in basal and agonist-dependent hormone release from dispersed goldfish (Carassius auratus) pituitary cells in perifusion experiments. Inhibition of these small GTPases elevated basal LH and GH secretion, except for Ras inhibition which only increased basal LH release. However, variable responses were observed with regard to LH and GH responses to the two goldfish native gonadotropin-releasing hormones (GnRH2 and GnRH3). GnRH-dependent LH release, but not GH secretion, was mediated by Arf1/6 GTPases. In contrast, inhibition of Rac and RhoA GTPases selectively enhanced GnRH3- and GnRH2-dependent GH release, respectively, while Ras inhibition only enhanced GnRH3-evoked LH secretion. Together, our results reveal novel divergent cell-type- and ligand-specific roles for small GTPases in the control of goldfish pituitary hormone exocytosis in unstimulated and GnRH-evoked release.

Targeting ARHGEF12 promotes neuroblastoma differentiation, MYCN degradation, and reduces tumorigenicity

PURPOSE

Neuroblastoma arises from developmental block of embryonic neural crest cells and is one of the most common and deadly pediatric tumors. However, the mechanism underlying this block is still unclear. Here, we show that targeting Rho guanine nucleotide exchange factor 12 (ARHGEF12, also named LARG) promotes MYCN degradation and neuroblastoma differentiation, leading to reduced neuroblastoma malignancy.

METHODS

The neuroblastoma TARGET dataset was downloaded to assess ARHGEF12 expression. Cell differentiation, proliferation, colony formation and cell migration analyses were performed to investigate the effects of ARHGEF12 knockdown on neuroblastoma cells. Western blotting and immunohistochemistry were employed to determine protein expression. Animal xenograft models were used to investigate antitumor effects after ARHGEF12 knockdown or treatment with the ARHGEF12 inhibitor Y16 in vivo.

RESULTS

We found that the expression level of ARHGEF12 was higher in neuroblastoma than in better-differentiated ganglioneuroblastoma. Knockdown of ARHGEF12 promoted neuroblastoma differentiation, decreased stemness-related gene expression, and increased differentiation-related gene expression. ARHGEF12 knockdown reduced tumor growth, and the resulting tumors showed bigger tumor cells compared to those in control neuroblastoma xenografts. In addition, it was found that ARHGEF12 knockdown promoted MYCN ubiquitination and degradation in MYCN-amplified tumors through RhoA/ROCK/GSK3β signaling. Targeting ARHGEF12 with the small molecular inhibitor Y16 induced cell differentiation and attenuated neuroblastoma tumorigenicity.

CONCLUSION

Our findings provide new insight into the mechanism by which ARHGEF12 regulates neuroblastoma tumorigenicity and suggest a translatable therapeutic approach by targeting ARHGEF12 with a small molecular inhibitor.

Apatinib Through Activating the RhoA/ROCK Signaling Pathway to Cause Dysfunction of Vascular Smooth Muscle Cells

Vascular smooth muscle cells (VSMCs) are associated with differentiated, organized, and contractile phenotype under the effect of various types of physiological conditions those are associated with migratory, proliferative, and synthetic phenotype under the effect of various types of stimuli, which dysfunction drives many cardiovascular diseases. Abnormal cell proliferation and invasion of VSMCs are among the primary causes of hypertension. Apatinib is a small-molecule tyrosine kinase inhibitor (TKI) that highly selectively binds to and strongly inhibits VEGFR-2. Previous studies have confirmed that the TKIs can raise blood pressure through RhoA/ROCK pathway. LARG is a key gene in the RhoA/ROCK pathway and plays a critical role in the continuous vasoconstriction function because it regulates part of signal transduction in VSMCs. In this study, an in vitro experiment was conducted to observe that apatinib caused dysfunction of MOVAS cells through the RhoA/ROCK signalling pathway and Y27632, a nonspecific ROCK inhibitor, and knockout of LARG gene can improve the proliferation, antiapoptosis, oxidative stress, and mitochondrial autophagy of apatinib-induced MOVAS cells. These findings suggest that activation of the RhoA/ROCK signalling pathway could be the underlying mechanism of apatinib-induced dysfunction of MOVAS cells, while ROCK inhibitor and knockout of LARG gene have potential therapeutic value.

Research on the Mechanism and Prevention of Hypertension Caused by Apatinib Through the RhoA/ROCK Signaling Pathway in a Mouse Model of Gastric Cancer

Hypertension is one of the main adverse effects of antiangiogenic tumor drugs and thus limits their application. The mechanism of hypertension caused by tyrosine kinase inhibitors (TKIs) targeting vascular endothelial growth factors is mainly related to inhibition of the nitric oxide (NO) pathway and activation of the endothelin pathway, as well as vascular rarefaction and increased salt sensitivity; consequently, prevention and treatment differ for this type of hypertension compared with primary hypertension. Apatinib is a highly selective TKI approved in China for the treatment of advanced or metastatic gastric cancer. The RhoA/ROCK pathway is involved in the pathogenesis of hypertension and mediates smooth muscle contraction, eNOS inhibition, endothelial dysfunction and vascular remodeling. In this study, in vivo experiments were performed to explore whether the RhoA/ROCK signaling pathway is part of a possible mechanism of apatinib in the treatment of gastric cancer-induced hypertension and the impairment of vascular remodeling and left ventricular function. Y27632, a selective small inhibitor of both ROCK1 and ROCK2, was combined with apatinib, and its efficacy was evaluated, wherein it can reduce hypertension induced by apatinib treatment in gastric cancer mice and weaken the activation of the RhoA/ROCK pathway by apatinib and a high-salt diet (HSD). Furthermore, Y-27632 improved aortic remodeling, fibrosis, endothelial dysfunction, superior mesenteric artery endothelial injury, left ventricular dysfunction and cardiac fibrosis in mice by weakening the activation of the RhoA/ROCK pathway. The expression of RhoA/ROCK pathway-related proteins and relative mRNA levels in mice after apatinib intervention were analyzed by various methods, and blood pressure and cardiac function indexes were compared. Endothelial and cardiac function and collagen levels in the aorta were also measured to assess vascular and cardiac fibrosis and to provide a basis for the prevention and treatment of this type of hypertension.