ROS-mediated downregulation of MYPT1 in smooth muscle cells: a potential mechanism for the aberrant contractility in atherosclerosis

Role of Protein Phosphatases in Tumor Angiogenesis: Assessing PP1, PP2A, PP2B and PTPs Activity

Tumor angiogenesis, the formation of new blood vessels to support tumor growth and metastasis, is a complex process regulated by a multitude of signaling pathways. Dysregulation of signaling pathways involving protein kinases has been extensively studied, but the role of protein phosphatases in angiogenesis within the tumor microenvironment remains less explored. However, among angiogenic pathways, protein phosphatases play critical roles in modulating signaling cascades. This review provides a comprehensive overview of the involvement of protein phosphatases in tumor angiogenesis, highlighting their diverse functions and mechanisms of action. Protein phosphatases are key regulators of cellular signaling pathways by catalyzing the dephosphorylation of proteins, thereby modulating their activity and function. This review aims to assess the activity of the protein tyrosine phosphatases and serine/threonine phosphatases. These phosphatases exert their effects on angiogenic signaling pathways through various mechanisms, including direct dephosphorylation of angiogenic receptors and downstream signaling molecules. Moreover, protein phosphatases also crosstalk with other signaling pathways involved in angiogenesis, further emphasizing their significance in regulating tumor vascularization, including endothelial cell survival, sprouting, and vessel maturation. In conclusion, this review underscores the pivotal role of protein phosphatases in tumor angiogenesis and accentuate their potential as therapeutic targets for anti-angiogenic therapy in cancer.

Identification of pivotal genes and regulatory networks associated with atherosclerotic carotid artery stenosis based on comprehensive bioinformatics analysis and machine learning

Objective

Bioinformatics methods were applied to investigate the pivotal genes and regulatory networks associated with atherosclerotic carotid artery stenosis (ACAS) and provide new insights for the treatment of this disease.

Methods

The study utilized five ACAS datasets (GSE100927, GSE11782, GESE28829, GSE41571, and GSE43292) downloaded from the NCBI GEO database. The first four datasets were combined as the training set (n = 99), while GSE43292 (n = 64) was used as the validation set. Difference analysis and functional enrichment analysis were then performed on the training set. The pathogenic targets of ACAS were screened by protein-protein interaction networks and MCODE analyses, combined with three machine learning algorithms. The results were next verified by analysis of inter-group differences and ROC curve analysis. Next, immune-related function and immune cell correlation analyses were performed, and plaques of human ACAS were applied to verify the results via immunohistochemistry (IH) and immunofluorescence (IF). Finally, the competing endogenous RNAs (ceRNA) and transcription factors (TFs) regulatory networks of the characterized genes were constructed.

Results

A total of 177 differentially expressed genes were identified, including 67 genes downregulated and 110 genes upregulated. Gene set enrichment analysis revealed that five pathways were active in the experimental group, including xenograft rejection, autoimmune thyroid disease, graft-versus-host disease, leishmaniasis infection, and lysosomes. Four key genes were identified, with C3AR1 being upregulated and FBLN5, PPP1R12A, and TPM1 being downregulated. The analysis of inter-group differences demonstrated that the four characterized genes were differentially expressed in both the control and experimental groups. The ROC analysis showed that they had high AUC values in both the training and validation sets. Therefore, a predictive ACAS patient nomogram model based on the screened genes was established. Correlation analysis revealed a positive correlation between C3AR1 expression and neutrophils, which was further validated in IH and IF. One or multiple lncRNAs may compete with the characterized genes for binding miRNAs. Additionally, each characterized gene interacts with multiple TFs.

Conclusion

Four pivotal genes were screened, and relevant ceRNA and TFs were predicted. These molecules may exert a crucial role in ACAS and serve as potential biomarkers and therapeutic targets.

New susceptibility alleles associated with severe coronary artery stenosis in the Lebanese population

BACKGROUND

Coronary Artery Disease (CAD) is the narrowing or blockage of the coronary arteries. It is closely associated with numerous genetics and environmental factors that have been extensively evaluated in various populations. In recent studies, severe phenotypes have been strongly linked to genetic risk factors.

METHODS

This study investigated the association of clinical, demographic, and genetic factors with severe coronary artery stenosis phenotypes in our population composed of 1734 individuals with severe coronary stenosis (≥ 50% in coronary vessels) and comparing them to 757 controls with no evidence of stenosis on angiography. We performed generalized linear model (GLM) genome-wide association studies to evaluate three stratification models and their associations to characteristics of the clinical disease. In model 1, patients were not stratified. In model 2, patients were stratified based on presence or absence of CAD family history (FxCAD). In model 3, patients were stratified by young age of CAD onset.

RESULTS

Eight SNPs (single nucleotide polymorphism) were significantly associated with severe CAD phenotypes in the various models [Formula: see text], four of these SNPs were associated with severe CAD and the four others were specifically significant for young CAD patients. While these SNPs were not previously reported for association with CAD, six of them are present in genes that have already been linked to coronary disease.

CONCLUSION

In conclusion, this study presents new genetic factors associated with severe stenosis and highlights different risk factors associated with a young age at diagnosis of CAD.

Role of smooth muscle cells in Cardiovascular Disease

Normally, smooth muscle cells (SMCs) are localized in the tunica media of the vasculature, where they take responsibility for vascular contraction and extracellular matrix (ECM) generation. SMCs also play a significant role in obedience and elastic rebound of the artery in response to the haemodynamic condition. However, under pathological or stressed conditions, phenotype switching from contractile to synthetic state or other cell types will occur in SMCs to positively or negatively contribute to disease progression. Various studies demonstrated that functional changes of SMCs are implicated in several cardiovascular diseases. In this review, we present the function of vascular SMCs (VSMCs) and the involved molecular mechanisms about phenotype switching, and summarize the roles of SMCs in atherosclerosis, hypertension, arterial aneurysms and myocardial infarction, hoping to obtain potential therapeutic targets against cardiovascular disease in the clinical practices.

Hydrogen peroxide promotes the expression of angiopoietin like 4 in RAW264.7 macrophages via MAPK pathways

Previous studies including some vivo experiments and large scale clinical trials have indicated that angiopoietin like 4 (ANGPTL4) is involved in atherosclerosis. However, the specific mechanism underlying the process remains unresolved. Similarly, cumulative evidence indicated that hydrogen peroxide (H2O2) is closely related to the occurrence and development of atherosclerosis. The current study investigated whether H2O2 treatment can affect ANGPTL4 release in macrophage cells cell viability assay, western blot analysis, ELISA and immunofluorescence. It was determined that treatment with 0.25 and 0.5 mM H2O2 resulted in a significant increase in ANGPTL4 protein expression in macrophage cells. Mitogen‑activated protein kinase (MAPK) pathways were implicated in the secretion of ANGPTL4 regulated by H2O2, and specific inhibitors of MAPK1 (also known as ERK) and p38 MAPK significantly decreased H2O2 induced ANGPTL4 protein expression. Accordingly, it was demonstrated that ANGPTL4 expression was regulated by H2O2 via ERK and p38 MAPK, but not the MAPK8 (also known as JNK) pathway. In view of the effects of H2O2 and ANGPTL4 on atherosclerosis, the influence of H2O2 on ANGPTL4 provided new insight into the mechanism of atherosclerosis.

Aging-related alterations in eNOS and nNOS responsiveness and smooth muscle reactivity of murine basilar arteries are modulated by apocynin and phosphorylation of myosin phosphatase targeting subunit-1

Aging causes major alterations of all components of the neurovascular unit and compromises brain blood supply. Here, we tested how aging affects vascular reactivity in basilar arteries from young (<10 weeks; y-BA), old (>22 months; o-BA) and old (>22 months) heterozygous MYPT1-T-696A/+ knock-in mice. In isometrically mounted o-BA, media thickness was increased by ∼10% while the passive length tension relations were not altered. Endothelial denudation or pan-NOS inhibition (100 µmol/L L-NAME) increased the basal tone by 11% in y-BA and 23% in o-BA, while inhibition of nNOS (1 µmol/L L-NPA) induced ∼10% increase in both ages. eNOS expression was ∼2-fold higher in o-BA. In o-BA, U46619-induced force was augmented (pEC50 ∼6.9 vs. pEC50 ∼6.5) while responsiveness to DEA-NONOate, electrical field stimulation or nicotine was decreased. Basal phosphorylation of MLC20-S19 and MYPT1-T-853 was higher in o-BA and was reversed by apocynin. Furthermore, permeabilized o-BA showed enhanced Ca2+-sensitivity. Old T-696A/+ BA displayed a reduced phosphorylation of MYPT1-T696 and MLC20, a lower basal tone in response to L-NAME and a reduced eNOS expression. The results indicate that the vascular hypercontractility found in o-BA is mediated by inhibition of MLCP and is partially compensated by an upregulation of endothelial NO release.

Altered Expression of Human Smooth Muscle Myosin Phosphatase Targeting (MYPT) Isovariants with Pregnancy and Labor

Background

Myosin light-chain phosphatase is a trimeric protein that hydrolyses phosphorylated myosin II light chains (MYLII) to cause relaxation in smooth muscle cells including those of the uterus. A major component of the phosphatase is the myosin targeting subunit (MYPT), which directs a catalytic subunit to dephosphorylate MYLII. There are 5 main MYPT family members (MYPT1 (PPP1R12A), MYPT2 (PPP1R12B), MYPT3 (PPP1R16A), myosin binding subunit 85 MBS85 (PPP1R12C) and TIMAP (TGF-beta-inhibited membrane-associated protein (PPP1R16B)). Nitric oxide (NO)-mediated smooth muscle relaxation has in part been attributed to activation of the phosphatase by PKG binding to a leucine zipper (LZ) dimerization domain located at the carboxyl-terminus of PPP1R12A. In animal studies, alternative splicing of PPP1R12A can lead to the inclusion of a 31-nucleotide exonic segment that generates a LZ negative (LZ-) isovariant rendering the phosphatase less sensitive to NO vasodilators and alterations in PPP1R12ALZ- and LZ+ expression have been linked to phenotypic changes in smooth muscle function. Moreover, PPP1R12B and PPP1R12C, but not PPP1R16A or PPP1R16B, have the potential for LZ+/LZ- alternative splicing. Yet, by comparison to animal studies, the information on human MYPT genomic sequences/mRNA expressions is scant. As uterine smooth muscle undergoes substantial remodeling during pregnancy we were interested in establishing the patterns of expression of human MYPT isovariants during this process and also following labor onset as this could have important implications for determining successful pregnancy outcome.

Objectives

We used cross-species genome alignment, to infer putative human sequences not available in the public domain, and isovariant-specific quantitative PCR, to analyse the expression of mRNA encoding putative LZ+ and LZ- forms of PPP1R12A, PPP1R12B and PPP1R12C as well as canonical PPP1R16A and PPP1R16B genes in human uterine smooth muscle from non-pregnant, pregnant and in-labor donors.

Results

We found a reduction in the expression of PPP1R12A, PPP1R12BLZ+, PPP1R16A and PPP1R16B mRNA in late pregnancy (not-in-labor) relative to non-pregnancy. PPP1R12ALZ+ and PPP1R12ALZ- mRNA levels were similar in the non-pregnant and pregnant not in labor groups. There was a further reduction in the uterine expression of PPP1R12ALZ+, PPP1R12CLZ+ and PPP1R12ALZ- mRNA with labor relative to the pregnant not-in-labor group. PPP1R12A, PPP1R12BLZ+, PPP1R16A and PPP1R16B mRNA levels were invariant between the not in labor and in-labor groups.

Conclusions

MYPT proteins are crucial determinants of smooth muscle function. Therefore, these alterations in human uterine smooth muscle MYPT isovariant expression during pregnancy and labor may be part of the important molecular physiological transition between uterine quiescence and activation.

Posterior Reversible Encephalopathy Syndrome with Extensive Deep White Matter Lesions Including the Temporal Pole

Posterior reversible encephalopathy syndrome (PRES) typically affects the posterior subcortical white matter. We report the case of a 55-year-old man with atypical PRES, who had malignant hypertension and renal dysfunction. Magnetic resonance imaging of the brain revealed extensive vasogenic edema in the deep white matter including the temporal pole, as well as in the brainstem and cerebellum. Antihypertensive therapy and hemodialysis contributed to both clinical and radiological improvement. Involvement of the deep white matter including the temporal pole, which is rarely affected in an ischemic stroke, should be recognized as a potential sign of PRES.

Bimodal effect of oxidative stress in internal anal sphincter smooth muscle

Changes in oxidative stress may affect basal tone and relaxation of the internal anal sphincter (IAS) smooth muscle in aging. We examined this issue by investigating the effects of the oxidative stress inducer 6-anilino-5,8-quinolinedione (LY-83583) in basal as well as U-46619-stimulated tone, and nonadrenergic, noncholinergic (NANC) relaxation in rat IAS. LY-83583, which works via generation of reactive oxygen species in living cells, produced a bimodal effect in IAS tone: lower concentrations (0.1 nM to 10 μM) produced a concentration-dependent increase, while higher concentrations (50-100 μM) produced a decrease in IAS tone. An increase in IAS tone by lower concentrations was associated with an increase in RhoA/Rho kinase (ROCK) activity. This was evident by the increase in RhoA/ROCK in the particulate fractions, in ROCK activity, and in the levels of phosphorylated (p) (Thr696)-myosin phosphatase target subunit 1 and p(Thr18/Ser19)-20-kDa myosin light chain. Conversely, higher concentrations of LY-83583 produced inhibitory effects on RhoA/ROCK. Interestingly, both the excitatory and inhibitory effects of LY-83583 in the IAS were reversed by superoxide dismutase. The excitatory effects of LY-83583 were found to resemble those with neuronal nitric oxide synthase (nNOS) inhibition by l-NNA, since it produced a significant increase in the IAS tone and attenuated NANC relaxation. These effects of LY-83583 and l-NNA were reversible by l-arginine. This suggests the role of nNOS inhibition and RhoA/ROCK activation in the increase in IAS tone by LY-83583. These data have important implications in the pathophysiology and therapeutic targeting of rectoanal disorders, especially associated with IAS dysfunction.

Association between the nicotinamide adenine dinucleotide phosphate oxidase p22phox gene -A930G polymorphism and intracerebral hemorrhage

The present study aimed to evaluate whether the ‑A930G polymorphism of the nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase p22phox gene is involved in intracerebral hemorrhage (ICH) in the Chinese Han population. In the present case‑control investigation, the subjects included 118 patients with ICH and 147 healthy controls. The ‑A930G polymorphism was determined using polymerase chain reaction and restriction fragment length polymorphism. Furthermore, the correlation between the ‑A930G gene polymorphism and ICH was evaluated using statistical analyses. The distribution of p22phox ‑A930G genotypes differed significantly between the two groups (P=0.003), with the AA, AG and GG genotype frequencies being 61.9, 29.3 and 8.8% in the control group and 40.7, 45.8 and 13.6% in the ICH group, respectively. The G allele frequency was significantly higher in patients with ICH compared with healthy controls (36.4 vs. 23.5%; P<0.05), however, the opposite was observed in the frequency of the A allele (63.6 vs. 76.5%; P<0.05). Binary logistic regression analysis revealed that genetic mutations of the p22phox ‑A930G gene were independent risk factors of ICH (odds ratio, 2.196; 95% confidence interval, 1.003‑4.586; P=0.009). In addition, certain conventional factors were associated with increased risk of ICH, including elevated blood pressure, increased levels of glucose and triglycerides in the blood, a history of hypertension and smoking. The ‑A930G polymorphism of the p22phox gene may affect the susceptibility to ICH and certain haplotypes of the gene may be associated with a higher susceptibility to ICH.

Inhibitory effects of phenolic compounds from Artocarpus styracifolius on respiratory burst of rat neutrophils

CONTEXT

Searching for polymorphonuclear neutrophils (PMNs) respiratory burst inhibitors is an important topic in the treatment of human diseases associated with inflammation.

OBJECTIVE

To investigate the inhibitory effects of phenolics isolated from Artocarpus styracifolius Pierre (Moraceae) on respiratory burst induced by phorbol myristate acetate (PMA).

MATERIALS AND METHODS

The anti-respiratory burst activities of eight phenolics (20 µM) were assessed by determining luminol-dependent chemiluminiscence in rat PMNs. Cytotoxicity of active compounds (1-1000 µM) was assayed by Trypan blue dye exclusion method. Cell-free models were employed to evaluate scavenging capacity of active compounds (20 µM) against reactive oxygen species.

RESULTS

The PMA-induced respiratory burst was significantly inhibited (p < 0.05) by six isoprenylated phenolics (AS1-6) at the concentration of 20 µM (below the toxic concentration) with the inhibition rate ranging from 25.0 to 99.6%. The inhibitory potency estimated by IC50 was in the order of AS1 (3.1 µM) >AS6 (5.9 µM) >AS2 (9.1 µM) >AS3 (10.0 µM) >AS5 (29.7 µM) >AS4 (57.7 µM). AS1-4, four isoprenylated flavones, potently quenched superoxide anion, hydroxyl radical, and hydrogen peroxide at the concentration of 20 µM with their scavenging rates in the range of 30.1-78.1%, 35.4-69.7%, and 65.5-86.3%, respectively. In contrast, AS5-6, two isoprenylated 2-arylbenzofurans, showed less effect than that exhibited by AS1-4.

CONCLUSION AND DISCUSSION

The isoprenylated phenolics from A. styracifolius can potently inhibit PMA-induced respiratory burst in rat neutrophils without showing cytotoxicity. The inhibitory effects of these isoprenylated phenolics on the respiratory burst might depend on their different types of structure.

Aging-associated oxidative stress leads to decrease in IAS tone via RhoA/ROCK downregulation

Internal anal sphincter (IAS) tone plays an important role in rectoanal incontinence (RI). IAS tone may be compromised during aging, leading to RI in certain patients. We examined the influence of oxidative stress in the aging-associated decrease in IAS tone (AADI). Using adult (4-6 mo old) and aging (24-30 mo old) rats, we determined the effect of oxidative stress on IAS tone and the regulatory RhoA/ROCK signal transduction cascade. We determined the effect of the oxidative stress inducer LY83583, which produces superoxide anions (O2 (·-)), on basal and stimulated IAS tone before and after treatment of intact smooth muscle strips and smooth muscle cells with the O2 (·-) scavenger SOD. Our data showed that AADI was associated with a decrease in RhoA/ROCK expression at the transcriptional and translational levels. Oxidative stress with a LY83583-mediated decrease in IAS tone and relaxation of IAS smooth muscle cells was associated with a decrease in RhoA/ROCK signal transduction, which was reversible by SOD. In addition, LY83583 caused a significant decrease in IAS contraction produced by the RhoA activator and a known RhoA/ROCK agonist, U46619, that was also reversible by SOD. The inhibitory effects of LY83583 and the ROCK inhibitor Y27632 on the U46619-induced increase in IAS tone were similar. We conclude that an increase in oxidative stress plays an important role in AADI in the elderly and may be one of the underlying mechanisms of RI in certain aging patients.