The myosin phosphatase targeting protein (MYPT) family: a regulated mechanism for achieving substrate specificity of the catalytic subunit of protein phosphatase type 1δ

Functional analysis of a novel nonsense PPP1R12A variant in a Chinese family with infantile epilepsy

BACKGROUND

Defects in PPP1R12A can lead to genitourinary and/or brain malformation syndrome (GUBS). GUBS is primarily characterized by neurological or genitourinary system abnormalities, but a few reported cases are associated with neonatal seizures. Here, we report a case of a female newborn with neonatal seizures caused by a novel variant in PPP1R12A, aiming to enhance the clinical and variant data of genetic factors related to epilepsy in early life.

METHODS

Whole-exome and Sanger sequencing were used for familial variant assessment, and bioinformatics was employed to annotate the variant. A structural model of the mutant protein was simulated using molecular dynamics (MD), and the free binding energy between PPP1R12A and PPP1CB was analyzed. A mutant plasmid was constructed, and mutant protein expression was analyzed using western blotting (WB), and the interaction between the mutant and PPP1CB proteins using co-immunoprecipitation (Co-IP) experiments.

RESULTS

The patient experienced tonic-clonic seizures on the second day after birth. Genetic testing revealed a heterozygous variant in PPP1R12A, NM_002480.3:c.2533 C > T (p.Arg845Ter). Both parents had the wild-type gene. MD suggested that loss of the C-terminal structure in the mutant protein altered its structural stability and increased the binding energy with PPP1CB, indicating unstable protein-protein interactions. On WB, a low-molecular-weight band was observed, indicating that the protein was truncated. Co-IP indicated that the mutant protein no longer interacted with PPP1CB, indicating an effect on the structural stability of the myosin phase complex.

CONCLUSION

The PPP1R12A c.2533 C > T variant may explain the neonatal seizures in the present case. The findings of this study expand the spectrum of PPP1R12A variants and highlight the potential significance of truncated proteins in the pathogenesis of GUBS.

Inflammatory lung injury is associated with endothelial cell mitochondrial fission and requires the nitration of RhoA and cytoskeletal remodeling

Higher levels of extracellular nicotinamide phosphoribosyltransferase (eNAMPT), a TLR4 agonist, are associated with poor clinical outcomes in sepsis-induced acute lung injury (ALI). Little is known regarding the mechanisms by which eNAMPT is involved in ALI. Our recent work has identified a crucial role for mitochondrial dysfunction in ALI. Thus, this study aimed to determine if eNAMPT-mediated inflammatory injury is associated with the loss of mitochondrial function. Our data show that eNAMPT disrupted mitochondrial bioenergetics. This was associated with cytoskeleton remodeling and the loss of endothelial barrier integrity. These changes were associated with enhanced mitochondrial fission and blocked when Rho-kinase (ROCK) was inhibited. The increases in mitochondrial fission were also associated with the nitration-mediated activation of the small GTPase activator of ROCK, RhoA. Blocking RhoA nitration decreased eNAMPT-mediated mitochondrial fission and endothelial barrier dysfunction. The increase in fission was linked to a RhoA-ROCK mediated increase in Drp1 (dynamin-related protein 1) at serine(S)616. Another TLR4 agonist, lipopolysaccharide (LPS), also increased mitochondrial fission in a Drp1 and RhoA-ROCK-dependent manner. To validate our findings in vivo, we challenged C57BL/6 mice with eNAMPT in the presence and absence of the Drp1 inhibitor, Mdivi-1. Mdivi-1 treatment protected against eNAMPT-induced lung inflammation, edema, and lung injury. These studies demonstrate that mitochondrial fission-dependent disruption of mitochondrial function is essential in TLR4-mediated inflammatory lung injury and identify a key role for RhoA-ROCK signaling. Reducing mitochondrial fission could be a potential therapeutic strategy to improve ARDS outcomes.

Action and therapeutic targets of myosin light chain kinase, an important cardiovascular signaling mechanism

The global incidence of cardiac diseases is increasing, imposing a substantial socioeconomic burden on healthcare systems. The pathogenesis of cardiovascular disease is complex and not fully understood, and the physiological function of the heart is inextricably linked to well-regulated cardiac muscle movement. Myosin light chain kinase (MLCK) is essential for myocardial contraction and diastole, cardiac electrophysiological homeostasis, vasoconstriction of vascular nerves and blood pressure regulation. In this sense, MLCK appears to be an attractive therapeutic target for cardiac diseases. MLCK participates in myocardial cell movement and migration through diverse pathways, including regulation of calcium homeostasis, activation of myosin light chain phosphorylation, and stimulation of vascular smooth muscle cell contraction or relaxation. Recently, phosphorylation of myosin light chains has been shown to be closely associated with the activation of myocardial exercise signaling, and MLCK mediates systolic and diastolic functions of the heart through the interaction of myosin thick filaments and actin thin filaments. It works by upholding the integrity of the cytoskeleton, modifying the conformation of the myosin head, and modulating innervation. MLCK governs vasoconstriction and diastolic function and is associated with the activation of adrenergic and sympathetic nervous systems, extracellular transport, endothelial permeability, and the regulation of nitric oxide and angiotensin II. Additionally, MLCK plays a crucial role in the process of cardiac aging. Multiple natural products/phytochemicals and chemical compounds, such as quercetin, cyclosporin, and ML-7 hydrochloride, have been shown to regulate cardiomyocyte MLCK. The MLCK-modifying capacity of these compounds should be considered in designing novel therapeutic agents. This review summarizes the mechanism of action of MLCK in the cardiovascular system and the therapeutic potential of reported chemical compounds in cardiac diseases by modifying MLCK processes.

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.

The MYPT2-regulated striated muscle-specific myosin light chain phosphatase limits cardiac myosin phosphorylation in vivo

The physiological importance of cardiac myosin regulatory light chain (RLC) phosphorylation by its dedicated cardiac myosin light chain kinase has been established in both humans and mice. Constitutive RLC-phosphorylation, regulated by the balanced activities of cardiac myosin light chain kinase and myosin light chain phosphatase (MLCP), is fundamental to the biochemical and physiological properties of myofilaments. However, limited information is available on cardiac MLCP. In this study, we hypothesized that the striated muscle-specific MLCP regulatory subunit, MYPT2, targets the phosphatase catalytic subunit to cardiac myosin, contributing to the maintenance of cardiac function in vivo through the regulation of RLC-phosphorylation. To test this hypothesis, we generated a floxed-PPP1R12B mouse model crossed with a cardiac-specific Mer-Cre-Mer to conditionally ablate MYPT2 in adult cardiomyocytes. Immunofluorescence microscopy using the gene-ablated tissue as a control confirmed the localization of MYPT2 to regions where it overlaps with a subset of RLC. Biochemical analysis revealed an increase in RLC-phosphorylation in vivo. The loss of MYPT2 demonstrated significant protection against pressure overload-induced hypertrophy, as evidenced by heart weight, qPCR of hypertrophy-associated genes, measurements of myocyte diameters, and expression of β-MHC protein. Furthermore, mantATP chase assays revealed an increased ratio of myosin heads distributed to the interfilament space in MYPT2-ablated heart muscle fibers, confirming that RLC-phosphorylation regulated by MLCP, enhances cardiac performance in vivo. Our findings establish MYPT2 as the regulatory subunit of cardiac MLCP, distinct from the ubiquitously expressed canonical smooth muscle MLCP. Targeting MYPT2 to increase cardiac RLC-phosphorylation in vivo may improve baseline cardiac performance, thereby attenuating pathological hypertrophy.

Genomic and Reverse Translational Analysis Discloses a Role for Small GTPase RhoA Signaling in the Pathogenesis of Schizophrenia: Rho-Kinase as a Novel Drug Target

Schizophrenia is one of the most serious psychiatric disorders and is characterized by reductions in both brain volume and spine density in the frontal cortex. RhoA belongs to the RAS homolog (Rho) family and plays critical roles in neuronal development and structural plasticity via Rho-kinase. RhoA activity is regulated by GTPase-activating proteins (GAPs) and guanine nucleotide exchange factors (GEFs). Several variants in GAPs and GEFs associated with RhoA have been reported to be significantly associated with schizophrenia. Moreover, several mouse models carrying schizophrenia-associated gene variants involved in RhoA/Rho-kinase signaling have been developed. In this review, we summarize clinical evidence showing that variants in genes regulating RhoA activity are associated with schizophrenia. In the last half of the review, we discuss preclinical evidence indicating that RhoA/Rho-kinase is a potential therapeutic target of schizophrenia. In particular, Rho-kinase inhibitors exhibit anti-psychotic-like effects not only in Arhgap10 S490P/NHEJ mice, but also in pharmacologic models of schizophrenia (methamphetamine- and MK-801-treated mice). Accordingly, we propose that Rho-kinase inhibitors may have antipsychotic effects and reduce cognitive deficits in schizophrenia despite the presence or absence of genetic variants in small GTPase signaling pathways.

From network analysis to experimental validation: identification of regulators of non-muscle myosin II contractility using the folded-gastrulation signaling pathway

The morphogenetic process of apical constriction, which relies on non-muscle myosin II (NMII) generated constriction of apical domains of epithelial cells, is key to the development of complex cellular patterns. Apical constriction occurs in almost all multicellular organisms, but one of the most well-characterized systems is the Folded-gastrulation (Fog)-induced apical constriction that occurs in Drosophila. The binding of Fog to its cognizant receptors Mist/Smog results in a signaling cascade that leads to the activation of NMII-generated contractility. Despite our knowledge of key molecular players involved in Fog signaling, we sought to explore whether other proteins have an undiscovered role in its regulation. We developed a computational method to predict unidentified candidate NMII regulators using a network of pairwise protein-protein interactions called an interactome. We first constructed a Drosophila interactome of over 500,000 protein-protein interactions from several databases that curate high-throughput experiments. Next, we implemented several graph-based algorithms that predicted 14 proteins potentially involved in Fog signaling. To test these candidates, we used RNAi depletion in combination with a cellular contractility assay in Drosophila S2R + cells, which respond to Fog by contracting in a stereotypical manner. Of the candidates we screened using this assay, two proteins, the serine/threonine phosphatase Flapwing and the putative guanylate kinase CG11811 were demonstrated to inhibit cellular contractility when depleted, suggestive of their roles as novel regulators of the Fog pathway.

FAT10 differentially stabilizes MYPT2 isoforms

Myosin phosphatase (MP) is an enzyme complex that regulates muscle contraction and plays important roles in various physiological and pathological conditions. Myosin phosphatase targeting subunit (MYPT) 2, a subunit of MP, interacts with protein phosphatase 1c to regulate its phosphatase activity. MYPT2 exists in various isoforms that differ in the composition of essential motifs that contribute to its function. However, regulatory mechanisms underlying these isoforms are poorly understood. Human leukocyte antigen-F adjacent transcript 10 (FAT10) is a ubiquitin-like modifier that not only targets proteins for proteasomal degradation but also stabilizes its interacting proteins. In this study, we investigated the effect of the interaction between FAT10 and MYPT2 isoform a (the canonical full-length form of MYPT2) or MYPT2 isoform f (the natural truncated form of MYPT2). FAT10 interacted with both MYPT2 isoforms a and f; however, only MYPT2 isoform f was increased by FAT10, whereas MYPT2 isoform a remained unaffected by FAT10. We further confirmed that, in contrast to MYPT2 isoform a, MYPT2 isoform f undergoes rapid degradation via the ubiquitin-proteasome pathway and that FAT10 stabilizes MYPT2 isoform f by inhibiting its ubiquitination. Therefore, our findings suggest that the interaction between FAT10 and MYPT2 isoforms leads to distinct stabilization effects on each isoform, potentially modulating MP activity.

Identification of miRNAs and target genes associated with lymph node metastasis in cervical cancer using bioinformatics analysis

This study was designed to identify the differentially expressed miRNAs (DEMs) and genes (DEGs) in metastatic cervical cancer using bioinformatic tools. In this study, fifty-seven DEMs (48 downregulated and 9 upregulated) were identified, among which miR-4459 and miR-3195 expression was negatively associated with overall survival of cervical cancer patients. Then, 476 target DEGs were determined, and protein-protein interaction (PPI) network was constructed. Seventeen hub genes (LONRF2, CCNE2, AURKA, SYT1, NEGR1, PPP1R12B, GABRP, RAD51, CDK1, FBLN5, PRKG1, CDC6, CACNA1C, MEOX2, ANLN, MYLK, and EDNRB) were finally selected to construct the miRNA-hub gene network. Overall, our study discovered the key miRNAs and mRNAs related to lymph node metastasis (LNM) in cervical cancer, which helps discover candidate therapeutic targets for cervical cancer.

Clinical report and genetic analysis of a neonate with genitourinary and/or brain malformation syndrome caused by a non-coding sequence variant of PPP1R12A

BACKGROUND

Genitourinary and/or brain malformation syndrome (GUBS) is a recently discovered syndrome involving abnormalities of the neurological or urogenital system. PPP1R12A may be the pathological gene causing this syndrome. Currently, to our knowledge, there is only one study related to GUBS in the world. Here, we report a clinical case of a Chinese newborn with congenital micropenis caused by a non-coding sequence pathogenic variant of PPP1R12A, providing additional evidence on genetic causes of genital malformation.

METHODS

The genetic cause of the patient's malformation was detected using trio-whole exome sequencing and Sanger sequencing, and reverse transcription-PCR analysis was performed by constructing the minigene mutant plasmid in vitro.

RESULTS

Genetic testing revealed a novel heterozygous variant, c.2666+3A>G, of the PPP1R12A gene of the patient. The parents at this site were wild-type, indicating that this might be a de novo variant. The minigene experiment showed that the c.2666+3A>G plasmid led to the deletion of 17 bp in exon 20, and a new mRNA product c.2650_2666del (p.Thr884IleTer2) with skipping of exon 20 was produced. This may lead to PPP1R12A haploinsufficiency and cause biological harm.

CONCLUSIONS

To our knowledge, this is the first clinical study on a rare variant of PPP1R12A in the Chinese population. The c.2666+3A>G may lead to external genitalia malformation, such as congenital micropenis in male neonates. The results of this study further verified the correlation between GUBS and PPP1R12A haploinsufficiency and revealed the important role of a non-coding sequence variant in the pathogenesis of the disease.

Circular RNAs with protein-coding ability in oncogenesis

As ubiquitously expressed transcripts in eukaryotes, circular RNAs (circRNAs) are covalently closed and lack a 5'-cap and 3'-polyadenylation (poly (A)) tail. Initially, circRNAs were considered non-coding RNA (ncRNA), and their roles as sponging molecules to adsorb microRNAs have been extensively reported. However, in recent years, accumulating evidence has demonstrated that circRNAs could encode functional polypeptides through the initiation of translation mediated by internal ribosomal entry sites (IRESs) or N6-methyladenosine (m6A). In this review, we collectively discuss the biogenesis, cognate mRNA products, regulatory mechanisms, aberrant expression and biological phenotypes or clinical relevance of all currently reported, cancer-relevant protein-coding circRNAs. Overall, we provide a comprehensive overview of circRNA-encoded proteins and their physiological and pathological functions.

Serine/Threonine Protein Phosphatases 1 and 2A in Lung Endothelial Barrier Regulation

Vascular barrier dysfunction is characterized by increased permeability and inflammation of endothelial cells (ECs), which are prominent features of acute lung injury (ALI), acute respiratory distress syndrome (ARDS), and sepsis, and a major complication of the SARS-CoV-2 infection and COVID-19. Functional impairment of the EC barrier and accompanying inflammation arises due to microbial toxins and from white blood cells of the lung as part of a defensive action against pathogens, ischemia-reperfusion or blood product transfusions, and aspiration syndromes-based injury. A loss of barrier function results in the excessive movement of fluid and macromolecules from the vasculature into the interstitium and alveolae resulting in pulmonary edema and collapse of the architecture and function of the lungs, and eventually culminates in respiratory failure. Therefore, EC barrier integrity, which is heavily dependent on cytoskeletal elements (mainly actin filaments, microtubules (MTs), cell-matrix focal adhesions, and intercellular junctions) to maintain cellular contacts, is a critical requirement for the preservation of lung function. EC cytoskeletal remodeling is regulated, at least in part, by Ser/Thr phosphorylation/dephosphorylation of key cytoskeletal proteins. While a large body of literature describes the role of phosphorylation of cytoskeletal proteins on Ser/Thr residues in the context of EC barrier regulation, the role of Ser/Thr dephosphorylation catalyzed by Ser/Thr protein phosphatases (PPases) in EC barrier regulation is less documented. Ser/Thr PPases have been proposed to act as a counter-regulatory mechanism that preserves the EC barrier and opposes EC contraction. Despite the importance of PPases, our knowledge of the catalytic and regulatory subunits involved, as well as their cellular targets, is limited and under-appreciated. Therefore, the goal of this review is to discuss the role of Ser/Thr PPases in the regulation of lung EC cytoskeleton and permeability with special emphasis on the role of protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) as major mammalian Ser/Thr PPases. Importantly, we integrate the role of PPases with the structural dynamics of the cytoskeleton and signaling cascades that regulate endothelial cell permeability and inflammation.

Phosphatase regulatory subunit MYPT2 knock-out partially compensates for the cardiac dysfunction in mice caused by lack of myosin light chain kinase 3

Cardiac contraction is modulated by the phosphorylation state of myosin regulatory light chain 2 (MLC-2v). The level of MLC-2v phosphorylation is dependent on the opposing activities of MLC kinases and phosphatases. The predominant MLC phosphatase found in cardiac myocytes contains Myosin Phosphatase Targeting Subunit 2 (MYPT2). Overexpression of MYPT2 in cardiac myocytes results in a decreased level of MLC phosphorylation, reduced left ventricular contraction and induction of hypertrophy; however, the effect of knocking out MYPT2 on cardiac function is unknown. We obtained heterozygous mice containing a MYPT2 null allele from the Mutant Mouse Resource Center. These mice were produced in a C57BL/6N background which lack MLCK3, the main regulatory light chain kinase in cardiac myocytes. We found that mice null for MYPT2 were viable and had no obvious phenotypic abnormality when compared to wild-type mice. Additionally, we determined that wild-type C57BL/6N mice had a low basal level of MLC-2v phosphorylation which was significantly increased when MYPT2 was absent. At 12-weeks, MYPT2 knock-out mice had smaller hearts and showed down-regulation of genes involved in cardiac remodeling. Using cardiac echo, we found that 24-week-old male MYPT2 knock-out mice had decreased heart size with increased fractional shortening compared to their MYPT2 wild-type littermates. Collectively, these studies highlight the important role that MYPT2 plays in cardiac function in vivo and demonstrate that its deletion can partially compensate for the lack of MLCK3.

Multi-Omics Profiling of Hypertrophic Cardiomyopathy Reveals Altered Mechanisms in Mitochondrial Dynamics and Excitation-Contraction Coupling

Hypertrophic cardiomyopathy is one of the most common inherited cardiomyopathies and a leading cause of sudden cardiac death in young adults. Despite profound insights into the genetics, there is imperfect correlation between mutation and clinical prognosis, suggesting complex molecular cascades driving pathogenesis. To investigate this, we performed an integrated quantitative multi-omics (proteomic, phosphoproteomic, and metabolomic) analysis to illuminate the early and direct consequences of mutations in myosin heavy chain in engineered human induced pluripotent stem-cell-derived cardiomyocytes relative to late-stage disease using patient myectomies. We captured hundreds of differential features, which map to distinct molecular mechanisms modulating mitochondrial homeostasis at the earliest stages of pathobiology, as well as stage-specific metabolic and excitation-coupling maladaptation. Collectively, this study fills in gaps from previous studies by expanding knowledge of the initial responses to mutations that protect cells against the early stress prior to contractile dysfunction and overt disease.

Anthocyanin actions at the gastrointestinal tract: Relevance to their health benefits

Anthocyanins (AC) are flavonoids abundant in the human diet, which consumption has been associated to several health benefits, including the mitigation of cardiovascular disease, type 2 diabetes, non-alcoholic fatty liver disease, and neurological disorders. It is widely recognized that the gastrointestinal (GI) tract is not only central for food digestion but actively participates in the regulation of whole body physiology. Given that AC, and their metabolites reach high concentrations in the intestinal lumen after food consumption, their biological actions at the GI tract can in part explain their proposed local and systemic health benefits. In terms of mechanisms of action, AC have been found to: i) inhibit GI luminal enzymes that participate in the absorption of lipids and carbohydrates; ii) preserve intestinal barrier integrity and prevent endotoxemia, inflammation and oxidative stress; iii) sustain goblet cell number, immunological functions, and mucus production; iv) promote a healthy microbiota; v) be metabolized by the microbiota to AC metabolites which will be absorbed and have systemic effects; and vi) modulate the metabolism of GI-generated hormones. This review will summarize and discuss the latest information on AC actions at the GI tract and their relationship to overall health benefits.

Inhibition of Rho-kinase ameliorates decreased spine density in the medial prefrontal cortex and methamphetamine-induced cognitive dysfunction in mice carrying schizophrenia-associated mutations of the Arhgap10 gene

Copy-number variations in the ARHGAP10 gene encoding Rho GTPase-activating protein 10 are associated with schizophrenia. Model mice (Arhgap10 S490P/NHEJ mice) that carry "double-hit" mutations in the Arhgap10 gene mimic the schizophrenia in a Japanese patient, exhibiting altered spine density, methamphetamine-induced cognitive dysfunction, and activation of RhoA/Rho-kinase signaling. However, it remains unclear whether the activation of RhoA/Rho-kinase signaling due to schizophrenia-associated Arhgap10 mutations causes the phenotypes of these model mice. Here, we investigated the effects of fasudil, a brain permeable Rho-kinase inhibitor, on altered spine density in the medial prefrontal cortex (mPFC) and on methamphetamine-induced cognitive impairment in a touchscreen‑based visual discrimination task in Arhgap10 S490P/NHEJ mice. Fasudil (20 mg/kg, intraperitoneal) suppressed the increased phosphorylation of myosin phosphatase-targeting subunit 1, a substrate of Rho-kinase, in the striatum and mPFC of Arhgap10 S490P/NHEJ mice. In addition, daily oral administration of fasudil (20 mg/kg/day) for 7 days ameliorated the reduced spine density of layer 2/3 pyramidal neurons in the mPFC. Moreover, fasudil (3-20 mg/kg, intraperitoneal) rescued the methamphetamine (0.3 mg/kg)-induced cognitive impairment of visual discrimination in Arhgap10 S490P/NHEJ mice. Our results suggest that Rho-kinase plays significant roles in the neuropathological changes in spine morphology and in the vulnerability of cognition to methamphetamine in mice with schizophrenia-associated Arhgap10 mutations.

Persistent Müllerian duct syndrome associated with genetic defects in the regulatory subunit of myosin phosphatase

STUDY QUESTION

Can mutations of genes other than AMH or AMHR2, namely PPP1R12A coding myosin phosphatase, lead to persistent Müllerian duct syndrome (PMDS)?

SUMMARY ANSWER

The detection of PPP1R12A truncation mutations in five cases of PMDS suggests that myosin phosphatase is involved in Müllerian regression, independently of the anti-Müllerian hormone (AMH) signaling cascade.

WHAT IS KNOWN ALREADY

Mutations of AMH and AMHR2 are detectable in an overwhelming majority of PMDS patients but in 10% of cases, both genes are apparently normal, suggesting that other genes may be involved.

STUDY DESIGN, SIZE, DURATION

DNA samples from 39 PMDS patients collected from 1990 to present, in which Sanger sequencing had failed to detect biallelic AMH or AMHR2 mutations, were screened by massive parallel sequencing.

PARTICIPANTS/MATERIALS, SETTING, METHODS

To rule out the possibility that AMH or AMHR2 mutations could have been missed, all DNA samples of good quality were analyzed by targeted next-generation sequencing. Twenty-four samples in which the absence of AMH or AMHR2 biallelic mutations was confirmed were subjected to whole-exome sequencing with the aim of detecting variants of other genes potentially involved in PMDS.

MAIN RESULTS AND THE ROLE OF CHANCE

Five patients out of 24 (21%) harbored deleterious truncation mutations of PP1R12A, the gene coding for the regulatory subunit of myosin phosphatase, were detected. In addition to PMDS, three of these patients presented with ileal and one with esophageal atresia. The congenital abnormalities associated with PMDS in our patients are consistent with those described in the literature for PPP1R12A variants and have never been described in cases of AMH or AMHR2 mutations. The role of chance is therefore extremely unlikely.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of the study is the lack of experimental validation of the role of PPP1R12A in Müllerian regression. Only circumstantial evidence is available, myosin phosphatase is required for cell mobility, which plays a major role in Müllerian regression. Alternatively, PPP1R12A mutations could affect the AMH transduction pathway.

WIDER IMPLICATIONS OF THE FINDINGS

The study supports the conclusion that failure of Müllerian regression in males is not necessarily associated with a defect in AMH signaling. Extending the scope of molecular analysis should shed light upon the mechanism of the initial steps of male sex differentiation.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by la Fondation Maladies Rares, GenOmics 2021_0404 and la Fondation pour la Recherche Médicale, grant EQU201903007868. The authors report no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

MYPT1-PP1β phosphatase negatively regulates both chromatin landscape and co-activator recruitment for beige adipogenesis

Protein kinase A promotes beige adipogenesis downstream from β-adrenergic receptor signaling by phosphorylating proteins, including histone H3 lysine 9 (H3K9) demethylase JMJD1A. To ensure homeostasis, this process needs to be reversible however, this step is not well understood. We show that myosin phosphatase target subunit 1- protein phosphatase 1β (MYPT1-PP1β) phosphatase activity is inhibited via PKA-dependent phosphorylation, which increases phosphorylated JMJD1A and beige adipogenesis. Mechanistically, MYPT1-PP1β depletion results in JMJD1A-mediated H3K9 demethylation and activation of the Ucp1 enhancer/promoter regions. Interestingly, MYPT1-PP1β also dephosphorylates myosin light chain which regulates actomyosin tension-mediated activation of YAP/TAZ which directly stimulates Ucp1 gene expression. Pre-adipocyte specific Mypt1 deficiency increases cold tolerance with higher Ucp1 levels in subcutaneous white adipose tissues compared to control mice, confirming this regulatory mechanism in vivo. Thus, we have uncovered regulatory cross-talk involved in beige adipogenesis that coordinates epigenetic regulation with direct activation of the mechano-sensitive YAP/TAZ transcriptional co-activators.

How β-AR signaling coordinates epigenetic and transcriptional pathways is unknown. Here the authors show that cold-induced β-AR signaling negatively regulates MYPT1-PP1β phosphatase activity to orchestrate both pathways for beige adipogenesis.

MYPT1 inhibits the metastasis of renal clear cell carcinoma via the MAPK8/N-cadherin pathway

Myosin phosphatase target subunit 1 (MYPT1) is a subunit of myosin phosphatase that is capable of regulating smooth muscle contraction. MYPT1 has been reported to be involved in a wide variety of tumours, but its expression and biological functions in renal clear cell carcinoma (ccRCC) remain obscure. Herein, we analysed the relationship between patient clinicopathological characteristics and MYPT1 expression levels in ccRCC patients using a tissue microarray (TMA) and data retrieved from the TCGA-KIRC dataset. MYPT1 was overexpressed or depleted using siRNA in ccRCC cells to assess the effects on migration and invasion in vitro and in vivo. Additionally, RNA-sequencing and bioinformatics analysis were performed to investigate the precise mechanism. MYPT1 expression in ccRCC tissues was observed to be lower than that in nonmalignant tissues (P < 0.05). In addition, MYPT1 downregulation was closely linked to advanced pathological stage (P < 0.05), and poor OS (overall survival; P < 0.05). Functionally, increased expression of MYPT1 suppressed ccRCC migration and invasion in vitro, and inhibited tumour metastasis in vivo. In addition, MYPT1 overexpression exerted its suppressive effects via the MAPK8/N-cadherin pathway in ccRCC.

Myosin light chain phosphatase catalytic subunit dephosphorylates cardiac myosin via mechanisms dependent and independent of the MYPT regulatory subunits

Cardiac muscle myosin regulatory light chain (RLC) is constitutively phosphorylated at ∼0.4 mol phosphate/mol RLC in normal hearts, and phosphorylation is maintained by balanced activities of dedicated cardiac muscle–specific myosin light chain kinase and myosin light chain phosphatase (MLCP). Previously, the identity of the cardiac-MLCP was biochemically shown to be similar to the smooth muscle MLCP, which is a well-characterized trimeric protein comprising the regulatory subunit (MYPT1), catalytic subunit PP1cβ, and accessory subunit M20. In smooth muscles in vivo, MYPT1 and PP1cβ co-stabilize each other and are both necessary for normal smooth muscle contractions. In the cardiac muscle, MYPT1 and MYPT2 are both expressed, but contributions to physiological regulation of cardiac myosin dephosphorylation are unclear. We hypothesized that the main catalytic subunit for cardiac-MLCP is PP1cβ, and maintenance of RLC phosphorylation in vivo is dependent on regulation by striated muscle–specific MYPT2. Here, we used PP1cβ conditional knockout mice to biochemically define cardiac-MLCP proteins and developed a cardiac myofibrillar phosphatase assay to measure the direct contribution of MYPT-regulated and MYPT-independent phosphatase activities toward phosphorylated cardiac myosin. We report that (1) PP1cβ is the main isoform expressed in the cardiac myocyte, (2) cardiac muscle pathogenesis in PP1cβ knockout animals involve upregulation of total PP1cα in myocytes and non-muscle cells, (3) the stability of cardiac MYPT1 and MYPT2 proteins in vivo is not dependent on the PP1cβ expression, and (4) phosphorylated myofibrillar cardiac myosin is dephosphorylated by both myosin-targeted and soluble MYPT-independent PP1cβ activities. These results contribute to our understanding of the cardiac-MLCP in vivo.

Effect of PPP1R14D gene high expression in lung adenocarcinoma knocked out on proliferation and apoptosis of DMS53 cell

PURPOSE

Globally, lung cancer remains the most commonly diagnosed cancer and the leading cause of cancer-related mortality. Lung adenocarcinoma (LUAD) is a common subtype of lung cancer and carries a poor prognosis. Treatment outcomes biomarkers in LUAD are critical, and there is currently a paucity of data; therefore, there is a need for novel biomarkers and newer therapeutic targets.

METHODS

Bayesian analysis was used to obtain the whole-genome t value of LUAD. Gene set enrichment analysis (GSEA) was conducted to obtain the normalized enrichment scores (NES) of the whole genome, and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway was analyzed using the Gene Set Analysis Toolkit. Herein, we investigated the PPP1R14D expression level at the protein level in LUAD and the impact of PPP1R14D knockdown on the proliferation and apoptosis of LUAD cells in vitro.

RESULTS

A total of 483 LUAD samples and 59 normal control samples were included, and 904 differentially expressed genes (DEGs) and 504 LUAD-related genes reported in the literature were obtained. The DEGs showed that PPP1R14D was the most significantly up-regulated gene. Western blot of 30 cases of LUAD tissue and adjacent normal tissue also found that PPP1R14D was significantly highly expressed in cancer tissues. Lentivirus-mediated shRNA strategy effectively inhibited PPP1R14D expression in human LUAD cells DMS53, while PPP1R14D knockdown induced apoptosis and cell proliferation in DMS53 cells.

CONCLUSION

Abnormally up-regulated PPP1R14D promotes the survival and proliferation of tumor cells in human LUAD and may serve as a therapeutic and diagnostic target for LUAD.

Circular RNA CDR1as Alleviates Cisplatin-Based Chemoresistance by Suppressing MiR-1299 in Ovarian Cancer

Cisplatin (CDDP) chemoresistance seriously affects the prognosis and survival of patients with ovarian cancer (OC). Previous research has shown that circular RNA CDR1as is biologically associated with a large number of cancers. However, the molecular mechanism underlying the role of CDR1as in CDDP chemoresistance in OC remains unclear. Here, we investigated the mechanism of CDR1as in CDDP-resistant OC. First, we employed bioinformatics analysis and quantitative real-time PCR (qRT-PCR) to determine the expression of CDR1as and related RNAs in CDDP-sensitive and -resistant OC tissues and cells. Then, functional experiments were used to determine cell proliferation, invasion, migration, and apoptosis in CDDP chemoresistance and parent OC cells in vitro. The effect of CDR1as in CDDP chemoresistance OC progression was tested in nude mice in vivo. Moreover, dual-luciferase assays and RNA immunoprecipitation (RIP) were performed to confirm the interactions of CDR1as and related RNAs. Finally, we used Western blotting to determine protein expression levels. Our findings interpret the underlying mechanisms of the CDR1as/miR-1299/PPP1R12B axis and shed light on the clinical applications for CDDP-chemoresistant OC.

A comprehensive gene expression profile of allergic rhinitis-derived nasal fibroblasts and the potential mechanism for its phenotype

BACKGROUND

Allergic rhinitis (AR) is a common immunoglobulin E-mediated immune response involved various cell types, while the role of nasal fibroblasts (NFs) in the pathogenesis of AR is less understood.

PURPOSE

The study aimed to uncover the gene expression profile of AR-derived NFs and the potential mechanism for the changed phenotype of AR-NFs.

RESEARCH DESIGN

The primary NFs were isolated from 3 AR patients (AR-NFs) and 3 controls (Ctrl-NFs), and the proliferation, migration and interleukins production abilities of NFs were detected respectively. RNA-sequence was used to identify differentially expressed genes (DEGs) in AR-NFs. Transcription factor (TF) regulatory network and bioinformatic analyses were both conducted to clarify the biological roles of DEGs including the TFs. The DEG with the highest validated |fold change (FC)| value, detected by qPCR, was selected for further confirmation.

RESULTS

AR-NFs showed a higher proliferation and migration abilities as well as released higher levels of IL-33 and IL-6, compared to Ctrl-NFs. A total of 729 DEGs were screened out in AR-NFs. TF regulatory network indicated that BARX homeobox 1 (BARX1) and forkhead box L1 were the major node TFs. Bioinformatic analyses showed that a large number of DEGs including several target genes of BARX1 were both enriched cytokine-related GO terms, and immune- or inflammation-related pathways. BARX1 had the highest |FC| value, and silencing BARX1 in AR-NFs resulted in the significant downregulation of proliferation and migration abilities, and the production of interleukins.

CONCLUSIONS

Our study for the first time provided the gene expression profile of AR-derived NFs, and BARX1 could be developed as a potent target to alleviate the pathogenesis of AR.

Novel γ-sarcoglycan interactors in murine muscle membranes

BACKGROUND

The sarcoglycan complex (SC) is part of a network that links the striated muscle cytoskeleton to the basal lamina across the sarcolemma. The SC coordinates changes in phosphorylation and Ca⁺⁺-flux during mechanical deformation, and these processes are disrupted with loss-of-function mutations in gamma-sarcoglycan (Sgcg) that cause Limb girdle muscular dystrophy 2C/R5.

METHODS

To gain insight into how the SC mediates mechano-signaling in muscle, we utilized LC-MS/MS proteomics of SC-associated proteins in immunoprecipitates from enriched sarcolemmal fractions. Criteria for inclusion were co-immunoprecipitation with anti-Sgcg from C57BL/6 control muscle and under-representation in parallel experiments with Sgcg-null muscle and with non-specific IgG. Validation of interaction was performed in co-expression experiments in human RH30 rhabdomyosarcoma cells.

RESULTS

We identified 19 candidates as direct or indirect interactors for Sgcg, including the other 3 SC proteins. Novel potential interactors included protein-phosphatase-1-catalytic-subunit-beta (Ppp1cb, PP1b) and Na⁺-K⁺-Cl^--co-transporter NKCC1 (SLC12A2). NKCC1 co-localized with Sgcg after co-expression in human RH30 rhabdomyosarcoma cells, and its cytosolic domains depleted Sgcg from cell lysates upon immunoprecipitation and co-localized with Sgcg after detergent permeabilization. NKCC1 localized in proximity to the dystrophin complex at costameres in vivo. Bumetanide inhibition of NKCC1 cotransporter activity in isolated muscles reduced SC-dependent, strain-induced increases in phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2). In silico analysis suggests that candidate SC interactors may cross-talk with survival signaling pathways, including p53, estrogen receptor, and TRIM25.

CONCLUSIONS

Results support that NKCC1 is a new SC-associated signaling protein. Moreover, the identities of other candidate SC interactors suggest ways by which the SC and NKCC1, along with other Sgcg interactors such as the membrane-cytoskeleton linker archvillin, may regulate kinase- and Ca⁺⁺-mediated survival signaling in skeletal muscle.

Possible roles of N- and C-terminal unstructured tails of CPI-17 in regulating Ca²⁺ sensitization force of smooth muscle

CPI-17 regulates the myosin phosphatase and mediates the agonist-induced contraction of smooth muscle. PKC and ROCK phosphorylate CPI-17 at Thr38 leading to a conformational change of the central inhibitory domain (PHIN domain). The N- and C-terminal tails of CPI-17 are predicted as unstructured loops and their sequences are conserved among mammals. Here we characterized CPI-17 N- and C-terminal unstructured tails using recombinant proteins that lack the potions. Recombinant CPI-17 proteins at a physiologic level (10 µM) were doped into beta-escin-permeabilized smooth muscle strips for Ca²⁺ sensitization force measurement. The ectopic full-length CPI-17 augmented the PDBu-induced Ca²⁺ sensitization force at pCa6.3, indicating myosin phosphatase inhibition. Deletion of N- and C-terminal tails of CPI-17 attenuated the extent of PDBu-induced Ca²⁺-sensitization force. The N-terminal deletion dampened phosphorylation at Thr38 by protein kinase C (PKC), and the C-terminal truncation lowered the affinity to the myosin phosphatase. Under the physiologic conditions, PKC and myosin phosphatase may recognize CPI-17 N-/C-terminal unstructured tails inducing Ca²⁺ sensitization force in smooth muscle cells.

Nebulization of risedronate alleviates airway obstruction and inflammation of chronic obstructive pulmonary diseases via suppressing prenylation-dependent RAS/ERK/NF-κB and RhoA/ROCK1/MLCP signaling

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a progressive disorder that causes airway obstruction and lung inflammation. The first-line treatment of COPD is the bronchodilators of β2-agonists and antimuscarinic drugs, which can help control the airway obstruction, but the long-term use might render the drug tolerance. Bisphosphonates are widely used in osteoclast-mediated bone diseases treatment for decades. For drug repurposing, can delivery of a third generation of nitrogen-containing bisphosphonate, risedronate (RIS) ameliorate the progression of COPD?

METHODS

COPD rats or mice models have been established through cigarette-smoking and elastase injection, and then the animals are received RIS treatment via nebulization. Lung deposition of RIS was primarily assessed by high-performance liquid chromatography (HPLC). The respiratory parameters of airway obstruction in COPD rats and mice were documented using plethysmography method and resistance-compliance system.

RESULTS

High lung deposition and bioavailability of RIS was monitored with 88.8% of RIS input dose. We found that RIS could rescue the lung function decline of airspace enlargement and mean linear intercept in the COPD lung. RIS could curb the airway obstruction by suppressing 60% of the respiratory resistance and elevating the airway's dynamic compliance, tidal volume and mid-expiratory flow. As an inhibitor of farnesyl diphosphate synthase (FDPS), RIS suppresses FDPS-mediated RAS and RhoA prenylation to obstruct its membrane localization in airway smooth muscle cells (ASMCs), leading to the inhibition of downstream ERK-MLCK and ROCK1-MLCP pathway to cause ASMCs relaxation. Additionally, RIS nebulization impeded pro-inflammatory cell accumulation, particularly macrophages infiltration in alveolar parenchyma. The NF-κB, tumor necrosis factor-alpha, IL-1β, IL-8, and IL-6 declined in microphages following RIS nebulization. Surprisingly, nebulization of RIS could overcome the tolerance of β2-agonists in COPD-rats by increasing the expression of β2 receptors.

CONCLUSIONS

Nebulization of RIS could alleviate airway obstruction and lung inflammation in COPD, providing a novel strategy for treating COPD patients, even those with β2-agonists tolerance.

Regulation of myosin light-chain phosphorylation and its roles in cardiovascular physiology and pathophysiology

The regulation of muscle contraction is a critical function in the cardiovascular system, and abnormalities may be life-threatening or cause illness. The common basic mechanism in muscle contraction is the interaction between the protein filaments myosin and actin. Although this interaction is primarily regulated by intracellular Ca²⁺, the primary targets and intracellular signaling pathways differ in vascular smooth muscle and cardiac muscle. Phosphorylation of the myosin regulatory light chain (RLC) is a primary molecular switch for smooth muscle contraction. The equilibrium between phosphorylated and unphosphorylated RLC is dynamically achieved through two enzymes, myosin light chain kinase, a Ca²⁺-dependent enzyme, and myosin phosphatase, which modifies the Ca²⁺ sensitivity of contractions. In cardiac muscle, the primary target protein for Ca²⁺ is troponin C on thin filaments; however, RLC phosphorylation also plays a modulatory role in contraction. This review summarizes recent advances in our understanding of the regulation, physiological function, and pathophysiological involvement of RLC phosphorylation in smooth and cardiac muscles.

Calcyphosine promotes the proliferation of glioma cells and serves as a potential therapeutic target

Calcyphosine (CAPS) was initially identified from the canine thyroid. It also exists in many types of tumor, but its expression and function in glioma remain unknown. Here we explored the clinical significance and the functional mechanisms of CAPS in glioma. We found that CAPS was highly expressed in glioma and high expression of CAPS was correlated with poor survival, in glioma patients and public databases. Cox regression analysis showed that CAPS was an independent prognostic factor for glioma patients. Knockdown of CAPS suppressed the proliferation, whereas overexpression of CAPS promoted the proliferation of glioma both in vitro and in vivo. CAPS regulated the G2/M phase transition of the cell cycle, but had no obvious effect on apoptosis. CAPS affected PLK1 phosphorylation through interaction with MYPT1. CAPS knockdown decreased p‐MYPT1 at S507 and p‐PLK1 at S210. Expression of MYPT1 S507 phosphomimic rescued PLK1 phosphorylation and the phenotype caused by CAPS knockdown. The PLK1 inhibitor volasertib enhanced the therapeutic effect of temozolomide in glioma. Our data suggest that CAPS promotes the proliferation of glioma by regulating the cell cycle and the PLK1 inhibitor volasertib might be a chemosensitizer of glioma. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

MX2-mediated innate immunity against HIV-1 is regulated by serine phosphorylation

The antiviral cytokine interferon activates expression of interferon-stimulated genes to establish an antiviral state. Myxovirus resistance 2 (MX2, also known as MxB) is an interferon-stimulated gene that inhibits the nuclear import of HIV-1 and interacts with the viral capsid and cellular nuclear transport machinery. Here, we identified the myosin light chain phosphatase (MLCP) subunits myosin phosphatase target subunit 1 (MYPT1) and protein phosphatase 1 catalytic subunit-β (PPP1CB) as positively-acting regulators of MX2, interacting with its amino-terminal domain. We demonstrated that serine phosphorylation of the N-terminal domain at positions 14, 17 and 18 suppresses MX2 antiviral function, prevents interactions with the HIV-1 capsid and nuclear transport factors, and is reversed by MLCP. Notably, serine phosphorylation of the N-terminal domain also impedes MX2-mediated inhibition of nuclear import of cellular karyophilic cargo. We also found that interferon treatment reduces levels of phosphorylation at these serine residues and outline a homeostatic regulatory mechanism in which repression of MX2 by phosphorylation, together with MLCP-mediated dephosphorylation, balances the deleterious effects of MX2 on normal cell function with innate immunity against HIV-1.

Characterization of Contractile Machinery of Vascular Smooth Muscles in Hypertension

Hypertension is a key risk factor for cardiovascular disease and it is a growing public health problem worldwide. The pathophysiological mechanisms of vascular smooth muscle (VSM) contraction contribute to the development of hypertension. Calcium (Ca²⁺)-dependent and -independent signaling mechanisms regulate the balance of the myosin light chain kinase and myosin light chain phosphatase to induce myosin phosphorylation, which activates VSM contraction to control blood pressure (BP). Here, we discuss the mechanism of the contractile machinery in VSM, especially RhoA/Rho kinase and PKC/CPI-17 of Ca²⁺ sensitization pathway in hypertension. The two signaling pathways affect BP in physiological and pathophysiological conditions and are highlighted in pulmonary, pregnancy, and salt-sensitive hypertension.

Upregulation of microRNA miR-141-3p and its prospective targets in endometrial carcinoma: a comprehensive study

The clinicopathological value of microRNA-141-3p (miR-141-3p) and its prospective target genes in endometrial carcinoma (EC) remains unclear. The present study determined the expression level of miR-141-3p in EC via quantitative real-time PCR (RT-qPCR). RT-qPCR showed a markedly higher expression level of miR-141-3p in EC tissues than in non-EC endometrium tissues (P < 0.0001). The microarray and miRNA-seq data revealed upregulation of miR-141-3p. Integrated analysis based on 675 cases of EC and 63 controls gave a standardized mean difference of 1.737, confirmed the upregulation of miR-141-3p. The Kaplan-Meier survival curve showed that a higher expression of miR-141-3p positively corelated with a poorer prognosis. Combining the predicted targets and downregulated genes in EC, we obtained 271 target genes for miR-141-3p in EC. Two potential targets, PPP1R12A and PPP1R12B, were downregulated at both the mRNA and protein levels. This study indicates that the overexpression of miR-141-3p may play an important part in the carcinogenesis of EC. The overexpression of miR-141-3p may be a risk factor for the prognosis of patients with EC.

The expression and clinical prognostic value of protein phosphatase 1 catalytic subunit beta in pancreatic cancer

Pancreatic cancer (PAAD) is a common malignancy with a poor survival rate. The identification of novel biomarkers could improve clinical outcomes for patients with PAAD. Here we evaluated the expression and clinical significance of PPP1CB in PAAD. PPP1CB expression was higher in PAAD tissue than in matched paracancerous tissue (P < 0.05). We predicted a network of regulatory targets and protein interaction partners of PPP1CB, and identified a PPI network consisting of 39 node genes. The expression of 33 node genes was higher in PAAD tissue than in matching paracancerous tissue. High expression of the node genes ACTN4, ANLN, CLTB, IQGAP1, SPTAN1, and TMOD3 was associated with improved overall survival (P < 0.05). SiRNA knockdown of PPP1CB significantly reduced the migration and invasion of PAAD cells. A PPP1CB immunohistochemical staining was performed using a tissue microarray (TMA), consisting of tumor samples collected from 91 patients with PAAD (88 of which contained matched paracancerous tissues). The expression of PPP1CB in PAAD was significantly higher than in the matched paracancerous tissue, (P = 0.016). High PPP1CB expression was associated with patient sex (P = 0.048), alcohol use (P = 0.039), CEA (P= 0.038), N stage (P = 0.001), and invasion of nerve (P = 0.036). Furthermore, high PPP1CB expression was associated with significantly poorer overall survival (P = 0.022). Our data demonstrate that PPP1CB is associated with the migration and invasion of PAAD cells, and may be useful as an independent prognostic indicator for clinical outcome in patients with PAAD.

Effect of Electroacupuncture on Bladder Dysfunction via Regulation of MLC and MLCK Phosphorylation in a Rat Model of Type 2 Diabetes Mellitus

Previous studies observed have reported that electroacupuncture (EA) is effective in relieving diabetic bladder dysfunction (DBD); however, little is known about the mechanism. Therefore, we explored the effects and mechanisms of EA on DBD in streptozotocin–high-fat diet- (STZ–HFD-) induced diabetic rats. The Sprague-Dawley male rats were divided randomly into four groups: normal group, diabetes mellitus group (DM group), DM with EA treatment group (EA group), and DM with sham EA treatment group (sham EA group). After 8 weeks of EA treatment, the body weight, serum glucose, bladder weight, and cystometrogram were evaluated. The bladder wall thickness was examined by abdominal ultrasound imaging. After the transabdominal ultrasound measurements, hematoxylin-eosin (HE) staining was used to observe the bladder mucosa layer. The bladder detrusor smooth muscle cells (SMCs) and fibroblasts were observed under transmission electron microscopy (TEM). The phospho-myosin light chain (p-MLC), phospho-myosin light chain kinase (p-MLCK), and phospho-myosin phosphatase target subunit 1 (p-MYPT1) levels in the bladder were examined using Western blot. The bladder weight, serum glucose, bladder wall thickness, volume threshold for micturition, and postvoid residual (PVR) volume in the diabetic rats were significantly higher than those in the control animals. EA treatment significantly reduced the bladder weight, bladder wall thickness, volume threshold for micturition, and PVR volume in diabetic rats. EA caused a significant increase in the MLC dephosphorylation and MLCK phosphorylation levels in the group compared to the sham EA and model groups. EA reduced the infiltration of inflammatory cells in the bladder mucosa layer of diabetic rats. In addition, EA repaired the damaged bladder detrusor muscle of diabetic rats by reducing mitochondrial damage of the SMCs and fibroblasts. Therefore, EA could reduce the bladder hypertrophy to ameliorate DBD by reversing the impairment in the mucosa layer and detrusor SMCs, which might be mainly mediated by the regulation of p-MLC and p-MLCK levels.

Mfge8 attenuates human gastric antrum smooth muscle contractions

Coordinated gastric smooth muscle contraction is critical for proper digestion and is adversely affected by a number of gastric motility disorders. In this study we report that the secreted protein Mfge8 (milk fat globule-EGF factor 8) inhibits the contractile responses of human gastric antrum muscles to cholinergic stimuli by reducing the inhibitory phosphorylation of the MYPT1 (myosin phosphatase-targeting subunit (1) subunit of MLCP (myosin light chain phosphatase), resulting in reduced LC20 (smooth muscle myosin regulatory light chain (2) phosphorylation. Mfge8 reduced the agonist-induced increase in the F-actin/G-actin ratios of β-actin and γ-actin1. We show that endogenous Mfge8 is bound to its receptor, α8β1 integrin, in human gastric antrum muscles, suggesting that human gastric antrum muscle mechanical responses are regulated by Mfge8. The regulation of gastric antrum smooth muscles by Mfge8 and α8 integrin functions as a brake on gastric antrum mechanical activities. Further studies of the role of Mfge8 and α8 integrin in regulating gastric antrum function will likely reveal additional novel aspects of gastric smooth muscle motility mechanisms.

MYPT1, regulated by miR-19b-3p inhibits the progression of non-small cell lung cancer via inhibiting the activation of wnt/β-catenin signaling

AIMS

Myosin phosphatase targeting protein 1 (MYPT1) was identified to function as a tumor suppressor in several kinds of cancers, but its role and the molecular mechanisms in non-small cell lung cancer (NSCLC) remain undiscovered. Herein, we aimed to reveal MYPT1 expression pattern and role in NSCLC, and investigate the underlying mechanisms.

MAIN METHODS

Sixty-eight paired NSCLC tissues and the adjacent normal tissues were included in this study. Western blotting and quantitative reverse transcription-polymerase chain (qPCR) technologies were applied for protein and RNA detection. CCK-8, colony formation, flow cytometry, wound healing, transwell chambers coated with Matrigel and in vivo experiments were applied to detect cell viability, colony formation, apoptosis, migration, invasiveness and tumorigenesis, respectively.

KEY FINDINGS

MYPT1 expressed at a lower level in NSCLC tissues as compared with the adjacent normal tissues, which predicted advanced clinic process and poor prognosis. Overexpression of MYPT1 resulted in obvious inhibitions in cell viability, colony formation, migration, invasiveness and tumorigenesis, and induced cell apoptotic rates, as well as decreased the expression levels of β-catenin and TCF4. Besides, overexpression of β-catenin weakened the above roles of MYPT1. In addition, the luciferase gene reporter assay verified that MYPT1 was a target of miR-19b-3p. Further experiments showed that miR-19b-3p promoted cell viability, invasiveness and migration and repressed cell apoptosis by targeting MYPT1.

SIGNIFICANCE

In conclusion, this study demonstrates that MYPT1, regulated by miR-19b-3p, inhibits the progression of NSCLC via inhibiting the activation of wnt/β-catenin signaling.

Editing of the myosin phosphatase regulatory subunit suppresses angiotensin II induced hypertension via sensitization to nitric oxide mediated vasodilation

Alternative splicing of exon 24 (E24) of the myosin phosphatase regulatory subunit (Mypt1) tunes smooth muscle sensitivity to NO/cGMP-mediated vasorelaxation and thereby controls blood pressure (BP) in otherwise normal mice. This occurs via the toggling in or out of a C-terminal leucine zipper (LZ) motif required for hetero-dimerization with and activation by cGMP-dependent protein kinase cGK1α. Here we tested the hypothesis that editing (deletion) of E24, by shifting to the LZ positive isoform of Mypt1, would suppress the hypertensive response to angiotensin II (AngII). To test this, mice underwent tamoxifen-inducible and smooth muscle-specific deletion of E24 (E24 cKO) at age 6 weeks followed by a chronic slow-pressor dose of AngII (400 ng/kg/min) plus additional stressors. E24 cKO suppressed the hypertensive response to AngII alone or with the addition of a high salt diet. This effect was not a function of altered salt balance as there were no differences in intake or renal excretion of sodium. This effect was NO dependent as L-NAME in the drinking water caused an exaggerated hypertensive response in the E24cKO mice. E24cKO mouse mesenteric arteries were more sensitive to DEA/NO-induced vasorelaxation and less responsive to AngII- and α-adrenergic-induced vasoconstriction at baseline. Only the latter two effects were still present after 2 weeks of chronic AngII treatment. We conclude that editing of Mypt1 E24, by shifting the expression of naturally occurring isoforms and sensitizing to NO-mediated vasodilation, could be a novel approach to the treatment of human hypertension.

Protective effects of curcumin against rat intestinal inflammation‑related motility disorders

Intestinal inflammation frequently occurs alongside dysmotility, which is characterized by altered myosin light chain phosphorylation levels. Curcumin, an active component from the ginger family, is reported to confer anti‑inflammatory effects. However, the effects of curcumin on both diarrhea and constipation associated inflammation remains to be elucidated. The present study was designed to investigate the effects of curcumin on diarrhea and constipation and to determine the related mechanisms. Sprague‑Dawley rats were used to establish diarrhea and constipation models via intracolonic acetic acid (4%) instillation or cold water gavage for 2 weeks, respectively. Blood samples were collected to measure the serum levels of the cytokines TNF‑α and IL‑1β using ELISA kits. Western blotting was performed to measure NF‑κB, RhoA, Rho‑related kinase 2, phosphorylated MLC₂₀, phosphorylated myosin phosphorylated target subunit 1, 130k Da‑MLC kinase (MLCK), c‑kit tyrosine kinase protein expression, and reverse transcription‑quantitative PCR was conducted to measure MLCK expression levels. The results indicated that curcumin reversed the elevations in the pro‑inflammatory cytokines IL‑1β and TNF‑α by inhibiting the NF‑κB pathway in rats with diarrhea and constipation. The results also indicated that myosin light chain (MLC) phosphorylation in intestinal smooth muscle was positively and negatively associated with the motility of inflammation‑related diarrhea and constipation in rats, respectively. Curcumin significantly reversed the increased MLC phosphorylation in the jejunum of the rats with diarrhea, significantly enhanced the reductions in inflammatory mediators, including TNF‑α and IL‑1β, of rats with constipation and significantly ameliorated the related hyper‑motility and hypo‑motility in rats with both diarrhea and constipation. In conclusion, the potential roles of the MLC kinase, c‑kit tyrosine and Rho A/Rho‑associated kinase 2 pathways, which are involved in curcumin‑induced amelioration of inflammation‑related diarrhea and constipation, were explored in the present study. Results from the present study suggested that curcumin has potential therapeutic value for treating intestinal inflammation and inflammation‑related motility disorders.

Myosin Phosphatase Is Implicated in the Control of THP-1 Monocyte to Macrophage Differentiation

Monocyte to macrophage differentiation is characterized by the activation of various signal transduction pathways, which may be modulated by protein phosphorylation; however, the impact of protein kinases and phosphatases is not well understood yet. It has been demonstrated that actomyosin rearrangement during macrophage differentiation is dependent on Rho-associated protein kinase (ROCK). Myosin phosphatase (MP) target subunit-1 (MYPT1) is one of the major cellular substrates of ROCK, and MP is often a counter enzyme of ROCK; therefore, MP may also control macrophage differentiation. Changes in MP activity and the effects of MP activation were studied on PMA or l,25(OH)₂D₃-induced differentiation of monocytic THP-1 cells. During macrophage differentiation, phosphorylation of MYPT1 at Thr696 and Thr853 increased significantly, resulting in inhibition of MP. The ROCK inhibitor H1152 and the MP activator epigallocatechin-3-gallate (EGCG) attenuated MYPT1 phosphorylation and concomitantly decreased the extent of phosphorylation of 20 kDa myosin light chain. H1152 and EGCG pretreatment also suppressed the expression of CD11b and weakened the PMA-induced adherence of the cells. Our results indicate that MP activation/inhibition contributes to the efficacy of monocyte to macrophage differentiation, and this enzyme may be a target for pharmacological interventions in the control of disease states that are affected by excessive macrophage differentiation.

Downregulation of Soluble Guanylate Cyclase and Protein Kinase G With Upregulated ROCK2 in the Pulmonary Artery Leads to Thromboxane A2 Sensitization in Monocrotaline-Induced Pulmonary Hypertensive Rats

Thromboxane A2 (TXA2) promotes various physiological responses including pulmonary artery (PA) contraction, and pathophysiological implications have been suggested in cardiovascular diseases including pulmonary hypertension. Here, we investigated the role of TXA2 receptor (TP)-mediated signaling in the pathophysiology of pulmonary arterial hypertension (PAH). The sensitivity of PA to the contractile agonist could be set by relaxing signals such as the nitric oxide (NO), soluble guanylate cyclase (sGC), and cGMP-dependent kinase (PKG) pathways. Changes in the TP agonist (U46619)-induced PA contraction and its modulation by NO/cGMP signaling were analyzed in a monocrotaline-induced PAH rat model (PAH-MCT). In the myograph study, PA from PAH-MCT showed higher responsiveness to U46619, that is decreased EC50. Immunoblot analysis revealed a lower expression of eNOS, sGC, and PKG, while there was a higher expression of RhoA-dependent kinase 2 (ROCK2) in the PA from PAH-MCT than in the control. In PAH-MCT, the higher sensitivity to U46619 was reversed by 8-Br-cGMP, a membrane-permeable cGMP analog, but not by the NO donor, sodium nitroprusside (SNP 30 μM). In contrast, in the control PA, inhibition of sGC by its inhibitor (1H- [1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ), 10 μM) lowered the threshold of U46619-induced contraction. In the presence of ODQ, SNP treatment had no effect whereas the addition of 8-Br-cGMP lowered the sensitivity to U46619. The inhibition of ROCK by Y-27632 attenuated the sensitivity to U46619 in both control and PAH-MCT. The study suggests that the attenuation of NO/cGMP signaling and the upregulation of ROCK2 increase the sensitivity to TXA2 in the PAH animal, which might have pathophysiological implications in patients with PAH.

Haplotype-based, case-control study of myosin phosphatase target subunit 1 (PPP1R12A) gene and hypertensive disorders of pregnancy

Objective: Hypertensive disorders of pregnancy (HDP) are thought to be a multifactorial genetic disease. Myosin light chain phosphorylation, which is involved in the regulation of vascular smooth muscle contraction and relaxation and thus contributes to the maintenance of blood pressure, is related to HDP. The official symbol of the gene for the production of MYPT1 protein is PPP1R12A gene. Thus, we investigated the possibility that the PPP1R12A gene is related to HDP. Methods: Subjects were 194 pregnant women with HDP and a control group of 262 pregnant women from those women examined. Four SNVs (rs7296839, rs11114256, rs2596793, and rs2694657) were selected from the PPP1R12A gene region. The HDP group was divided according to disease type, and each group was analyzed in comparison with the control group. Results: In the association analysis using the PPP1R12A gene, there were significant differences between the control group and the superimposed preeclampsia (SPE) group for rs11114256 in allele frequency distribution (P = 0.017) and genome frequency distribution in the dominant model (P = 0.014), and for rs2694657 genotype distribution frequency in the recessive model (P = 0.018). In the association analysis using haplotypes, there was a significant difference for G-A-A-G (rs7296839-rs11114256-rs2596793-rs2694657). In an analysis of haplotype-based case-control study, there was a significant difference for G-A-A-G between the control group (0.00%) and the HDP group (2.46%) (P = 0.038). Furthermore, the G-T-A-G haplotype was significantly higher in SPE group than in control group (P = 0.011). Conclusions: The implication is that the PPP1R12A gene may be a disease-susceptibility gene for SPE.

Myosin light chain kinase regulates intestinal permeability of mucosal homeostasis in Crohn's disease

Introduction: Researchers have investigated the potential role of intestinal permeability in Crohn's disease pathogenesis. Intestinal permeability is usually mediated by cytoskeleton and intercellular junctions. The myosin light chain kinase (MLCK) is an enzyme that activates the myosin light chain to exert its function related to cytoskeleton contraction and tight junction regulation. The correlation between MLCK and Crohn's disease pathogenesis has been consistently proven. Areas covered: This study aims to expand the understanding of the regulation and function of MLCK in Crohn's disease. An extensive literature search in the MEDLINE database (via PubMed) has been performed up to Oct. 2020. The roles of MLCK in tight junction activation, intestinal permeability enhancement, and cell signal regulation are comprehensively discussed. Expert opinion: Targeting the MLCK-related pathways such as TNF-α in CD treatment has been put into clinical use. More accurate targeting such as MLCK and TNFR2 has been proposed to reduce side effects. MLCK may also have the potential to become biomarkers in fields like CD activity. With the application of cutting age research methods and tools, the MLCK research could be accelerated.

The adenoviral protein E4orf4: a probing tool to decipher mechanical stress-induced nuclear envelope remodeling in tumor cells

The human adenovirus (Ad) type 2/5 early region 4 (E4) ORF4 protein (E4orf4) exerts a remarkable tumor cell-selective killing activity in mammalian cells. This indicates that E4orf4 can target tumor cell-defining features and is a unique tool to probe cancer cell vulnerabilities. Recently, we found that E4orf4, through an interaction with the polarity protein PAR3, subverts nuclear envelope (NE) remodeling processes in a tumor cell-selective manner. In this Perspective, we outline mechanical signals that modify nuclear dynamics and tumor cell behavior to highlight potential mechanisms for E4orf4's tumoricidal activity. Through an analysis of E4orf4's cellular targets, we define a protein subnetwork that comprises phosphatase systems interconnected to polarity protein hubs, which could contribute to enhanced NE plasticity. We infer that elucidating E4orf4's protein network at a functional level could uncover key mechanisms of NE remodeling that define the tumor cell phenotype.

Water-Pipe Smoking Exposure Deregulates a Set of Genes Associated with Human Head and Neck Cancer Development and Prognosis

Water-pipe smoking (WPS) is becoming the most popular form of tobacco use among the youth, especially in the Middle East, replacing cigarettes rapidly and becoming a major risk of tobacco addiction worldwide. Smoke from WPS contains similar toxins as those present in cigarette smoke and is linked directly with different types of cancers including lung and head and neck (HN) carcinomas. However, the underlying molecular pathways and/or target genes responsible for the carcinogenic process are still unknown. In this study, human normal oral epithelial (HNOE) cells, NanoString PanCancer Pathways panel of 770 gene transcripts and quantitative real-time polymerase chain reaction (qRT-PCR) analysis were applied to discover differentially expressed genes (DEG) modulated by WPS. In silico analysis was performed to analyze the impact of these genes in HN cancer patient’s biology and outcome. We found that WPS can induce the epithelial–mesenchymal transition (EMT: hallmark of cancer progression) of HNOE cells. More significantly, our analysis of NanoString revealed 23 genes deregulated under the effect of WPS, responsible for the modulation of cell cycle, proliferation, migration/invasion, apoptosis, signal transduction, and inflammatory response. Further analysis was performed using qRT-PCR of HNOE WPS-exposed and unexposed cells supported the reliability of our NanoString data. Moreover, we demonstrate those DEG to be upregulated in cancer compared with normal tissue. Using the Kaplan–Meier analysis, we observed a significant association between WPS-deregulated genes and relapse-free survival/overall survival in HN cancer patients. Our findings imply that WPS can modulate EMT as well as a set of genes that are directly involved in human HN carcinogenesis, thereby affecting HN cancer patients’ survival.

MYPT1 O-GlcNAc modification regulates sphingosine-1-phosphate mediated contraction

Many intracellular proteins are modified by N-acetylglucosamine, a posttranslational modification termed O-GlcNAc. This modification is found on serine and threonine side-chains and has the potential to regulate signaling pathways through interplay with phosphorylation. Here, we discover and characterize one such example. We find that O-GlcNAc levels control the sensitivity of fibroblasts to actin contraction induced by the signaling lipid sphingosine-1-phosphate (S1P), culminating in the phosphorylation of myosin light chain (MLC) and cellular contraction. Specifically, O-GlcNAc modification of the phosphatase subunit MYPT1 inhibits this pathway by blocking MYPT1 phosphorylation, maintaining its activity and causing the dephosphorylation of MLC. Finally, we demonstrate that O-GlcNAc levels alter the sensitivity of primary human dermal fibroblasts in a collagen-matrix model of wound healing. Our findings have important implications for the role of O-GlcNAc in fibroblast motility and differentiation, particularly in diabetic wound healing.

Non-Muscle Myosin II in Axonal Cell Biology: From the Growth Cone to the Axon Initial Segment

By binding to actin filaments, non-muscle myosin II (NMII) generates actomyosin networks that hold unique contractile properties. Their dynamic nature is essential for neuronal biology including the establishment of polarity, growth cone formation and motility, axon growth during development (and axon regeneration in the adult), radial and longitudinal axonal tension, and synapse formation and function. In this review, we discuss the current knowledge on the spatial distribution and function of the actomyosin cytoskeleton in different axonal compartments. We highlight some of the apparent contradictions and open questions in the field, including the role of NMII in the regulation of axon growth and regeneration, the possibility that NMII structural arrangement along the axon shaft may control both radial and longitudinal contractility, and the mechanism and functional purpose underlying NMII enrichment in the axon initial segment. With the advances in live cell imaging and super resolution microscopy, it is expected that in the near future the spatial distribution of NMII in the axon, and the mechanisms by which it participates in axonal biology will be further untangled.

The Evolution of Duplicated Genes of the Cpi-17/Phi-1 (ppp1r14) Family of Protein Phosphatase 1 Inhibitors in Teleosts

The Cpi-17 (ppp1r14) gene family is an evolutionarily conserved, vertebrate specific group of protein phosphatase 1 (PP1) inhibitors. When phosphorylated, Cpi-17 is a potent inhibitor of myosin phosphatase (MP), a holoenzyme complex of the regulatory subunit Mypt1 and the catalytic subunit PP1. Myosin phosphatase dephosphorylates the regulatory myosin light chain (Mlc2) and promotes actomyosin relaxation, which in turn, regulates numerous cellular processes including smooth muscle contraction, cytokinesis, cell motility, and tumor cell invasion. We analyzed zebrafish homologs of the Cpi-17 family, to better understand the mechanisms of myosin phosphatase regulation. We found single homologs of both Kepi (ppp1r14c) and Gbpi (ppp1r14d) in silico, but we detected no expression of these genes during early embryonic development. Cpi-17 (ppp1r14a) and Phi-1 (ppp1r14b) each had two duplicate paralogs, (ppp1r14aa and ppp1r14ab) and (ppp1r14ba and ppp1r14bb), which were each expressed during early development. The spatial expression pattern of these genes has diverged, with ppp1r14aa and ppp1r14bb expressed primarily in smooth muscle and skeletal muscle, respectively, while ppp1r14ab and ppp1r14ba are primarily expressed in neural tissue. We observed that, in in vitro and heterologous cellular systems, the Cpi-17 paralogs both acted as potent myosin phosphatase inhibitors, and were indistinguishable from one another. In contrast, the two Phi-1 paralogs displayed weak myosin phosphatase inhibitory activity in vitro, and did not alter myosin phosphorylation in cells. Through deletion and chimeric analysis, we identified that the difference in specificity for myosin phosphatase between Cpi-17 and Phi-1 was encoded by the highly conserved PHIN (phosphatase holoenzyme inhibitory) domain, and not the more divergent N- and C- termini. We also showed that either Cpi-17 paralog can rescue the knockdown phenotype, but neither Phi-1 paralog could do so. Thus, we provide new evidence about the biochemical and developmental distinctions of the zebrafish Cpi-17 protein family.

Controlling Ser/Thr protein phosphatase PP1 activity and function through interaction with regulatory subunits

Protein phosphatase 1 is a major Ser/Thr protein phosphatase activity in eukaryotic cells. It is composed of a catalytic polypeptide (PP1C), with little substrate specificity, that interacts with a large variety of proteins of diverse structure (regulatory subunits). The diversity of holoenzymes that can be formed explain the multiplicity of cellular functions under the control of this phosphatase. In quite a few cases, regulatory subunits have an inhibitory role, downregulating the activity of the phosphatase. In this chapter we shall introduce PP1C and review the most relevant families of PP1C regulatory subunits, with particular emphasis in describing the structural basis for their interaction.

Regulation of Myosin Light-Chain Phosphatase Activity to Generate Airway Smooth Muscle Hypercontractility

Smooth muscle is a central structure involved in the regulation of airway tone. In addition, it plays an important role in the development of some pathologies generated by alterations in contraction, such as hypercontractility and the airway hyperresponsiveness observed in asthma. The molecular processes associated with smooth muscle contraction are centered around myosin light chain (MLC) phosphorylation, which is controlled by a balance in the activity of myosin light-chain kinase (MLCK) and myosin light-chain phosphatase (MLCP). MLCK activation depends on increasing concentrations of intracellular Ca²⁺, while MLCP activation is independent of Ca²⁺. MLCP contains a phosphatase subunit (PP1c) that is regulated through myosin phosphatase target subunit 1 (MYPT1) and other subunits, such as glycogen-associated regulatory subunit and myosin-binding subunit 85 kDa. Interestingly, MLCP inhibition may contribute to exacerbation of smooth muscle contraction by increasing MLC phosphorylation to induce hypercontractility. Many pathways inhibiting MLCP activity in airway smooth muscle have been proposed and are focused on inhibition of PP1c, inhibitory phosphorylation of MYPT1 and dissociation of the PP1c-MYPT1 complex.

Protein phosphatase 1 activity controls a balance between collective and single cell modes of migration

Collective cell migration is central to many developmental and pathological processes. However, the mechanisms that keep cell collectives together and coordinate movement of multiple cells are poorly understood. Using the Drosophila border cell migration model, we find that Protein phosphatase 1 (Pp1) activity controls collective cell cohesion and migration. Inhibition of Pp1 causes border cells to round up, dissociate, and move as single cells with altered motility. We present evidence that Pp1 promotes proper levels of cadherin-catenin complex proteins at cell-cell junctions within the cluster to keep border cells together. Pp1 further restricts actomyosin contractility to the cluster periphery rather than at individual internal border cell contacts. We show that the myosin phosphatase Pp1 complex, which inhibits non-muscle myosin-II (Myo-II) activity, coordinates border cell shape and cluster cohesion. Given the high conservation of Pp1 complexes, this study identifies Pp1 as a major regulator of collective versus single cell migration.

NO-Releasing Nanoparticles Ameliorate Detrusor Overactivity in Transgenic Sickle Cell Mice via Restored NO/ROCK Signaling

Sickle cell disease (SCD) is associated with overactive bladder (OAB). Detrusor overactivity, a component of OAB, is present in an SCD mouse, but the molecular mechanisms for this condition are not well-defined. We hypothesize that nitric oxide (NO)/ ras homolog gene family (Rho) A/Rho-associated kinase (ROCK) dysregulation is a mechanism for detrusor overactivity and that NO-releasing nanoparticles (NO-nps), a novel NO delivery system, may serve to treat this condition. Male adult SCD transgenic, combined endothelial NO synthases (eNOSs) and neuronal NOS (nNOS) gene-deficient (dNOS^-/-), and wild-type (WT) mice were used. Empty nanoparticle or NO-np was injected into the bladder, followed by cystometric studies. The expression levels of phosphorylated eNOS (Ser-1177), protein kinase B (Akt) (Ser-473), nNOS (Ser-1412), and myosin phosphatase target subunit 1 (MYPT1) (Thr-696) were assessed in the bladder. SCD and dNOS^-/- mice had a greater (P < 0.05) number of voiding and nonvoiding contractions compared with WT mice, and they were normalized by NO-np treatment. eNOS (Ser-1177) and AKT (Ser-473) phosphorylation were decreased (P < 0.05) in the bladder of SCD compared with WT mice and reversed by NO-np. Phosphorylated MYPT1, a marker of the RhoA/ROCK pathway, was increased (P < 0.05) in the bladder of SCD mice compared with WT and reversed by NO-np. nNOS phosphorylation on positive (Ser-1412) regulatory site was decreased (P < 0.05) in the bladder of SCD mice compared with WT and was not affected by NO-np. NO-nps did not affect any of the measured parameters in WT mice. In conclusion, dysregulation of NO and RhoA/ROCK pathways is associated with detrusor overactivity in SCD mice; NO-np reverses these molecular derangements in the bladder and decreases detrusor overactivity. SIGNIFICANCE STATEMENT: Voiding abnormalities commonly affect patients with sickle cell disease (SCD) but are problematic to treat. Clarification of the science for this condition in an animal model of SCD may lead to improved interventions for it. Our findings suggest that novel topical delivery of a vasorelaxant agent nitric oxide into the bladder of these mice corrects overactive bladder by improving deranged bladder physiology regulatory signaling.