Myosin Phosphatase Target Protein Research Articles

TIMAP, a Regulatory Subunit of Protein Phosphatase 1, Inhibits In Vitro Neuronal Differentiation.

TIMAP (TGF-β-inhibited membrane associated protein) is abundant in endothelial cells, and it has been regarded as a member of the myosin phosphatase targeting protein (MYPT) family. Our workgroup previously identified several interacting protein partners of TIMAP and proved its regulatory subunit role for protein phosphatase 1 catalytic subunit (PP1c). TIMAP is also expressed in neuronal cells, but details of its function have not been studied yet. Therefore, we aimed to explore the role of TIMAP in neuronal cells, especially during differentiation. Expression of TIMAP was proved both at mRNA and protein levels in SH-SY5Y human neuroblastoma cells. Differentiation of SH-SY5Y cells was optimized and proved by the detection of neuronal differentiation markers, such as β3-tubulin, nestin and inhibitor of differentiation 1 (ID1) using qPCR and Western blot. We found downregulation of TIMAP during differentiation. In accordance with this, overexpression of recombinant TIMAP attenuated the differentiation of neuronal cells. Moreover, the subcellular localization of TIMAP has changed during differentiation as it translocated from the plasma membrane into the nucleus. The nuclear interactome of TIMAP revealed more than 50 proteins, offering the possibility to further investigate the role of TIMAP in several key physiological pathways of neuronal cells.

N6-methyladenosine-modified microRNA-675 advances the development of gastrointestinal stromal tumors via inhibiting myosin phosphatase targeting protein 1

RNA N6-methyladenosine (m6A) modifications influence gastrointestinal stromal tumors (GISTs) development, but the detailed molecular mechanisms have not been fully studied. Here, microRNA-675 was found to be aberrantly elevated in cancerous tissues and cells of GISTs, compared to the corresponding normal counterparts, and GISTs patients with high-expressed microRNA-675 have worse outcomes. Additional experiments confirmed that silencing of microRNA-675 hindered cell division, mobility and tumorigenesis in vitro and in vivo, whereas triggered apoptotic cell death in GISTs cells. Furthermore, microRNA-675-ablation increased the expression levels of myosin phosphatase targeting protein 1 (MYPT1) to inactivate the tumor-initiating RhoA/NF2/YAP1 signal pathway, and downregulation of MYPT1 recovered the malignant phenotypes in microRNA-675-silenced GISTs cells. In addition, we evidenced that METTL3-mediated m6A modifications were essential for sustaining the stability of microRNA-675, and silencing of METTL3 restrained tumorigenesis of GISTs cells by regulating the microRNA-675/MYPT1 axis. To summarize, theMETTL3/m6A/microRNA-675/MYPT1 axis could be used as novel biomarkers for the diagnosis and treatment of GISTs.

RND3 attenuates oxidative stress and vascular remodeling in spontaneously hypertensive rat via inhibiting ROCK1 signaling

Superoxide and vascular smooth muscle cells (VSMCs) migration and proliferation play crucial roles in the vascular remodeling. Vascular remodeling contributes to the development and complications of hypertension. Rho family GTPase 3 (RND3 or RhoE), an atypical small Rho-GTPase, is known to be involved in cancer development and metastasis. However, the roles of RND3 in superoxide production and cardiovascular remodeling are unknown. Here, we uncovered the critical roles of RND3 in attenuating superoxide production, VSMCs migration and proliferation, and vascular remodeling in hypertension and its underline mechanisms. VSMCs were isolated and prepared from thoracic aorta of Male Wistar-Kyoto rat (WKY) and spontaneously hypertensive rat (SHR). RND3 mRNA and protein expressions in arteries and VSMCs were down-regulated in SHR. RND3 overexpression in VSMCs reduced NAD(P)H oxidase (NOX) activity, NOX1 and NOX2 expressions, mitochondria superoxide generation, and H2O2 production in SHR. Moreover, the RND3 overexpression inhibited VSMCs migration and proliferation in SHR, which were similar to the effects of NOX1 inhibitor ML171 plus NOX2 inhibitor GSK2795039. Rho-associated kinase 1 (ROCK1) and RhoA expressions and myosin phosphatase targeting protein 1 (MYPT1) phosphorylation in VSMCs were increased in SHR, which were prevented by RND3 overexpression. ROCK1 overexpression promoted NOX1 and NOX2 expressions, superoxide and H2O2 production, VSMCs migration and proliferation in both WKY and SHR, which were attenuated by RND3 overexpression. Adenoviral-mediated RND3 overexpression in SHR attenuated hypertension, vascular remodeling and oxidative stress. These results indicate that RND3 attenuates VSMCs migration and proliferation, hypertension and vascular remodeling in SHR via inhibiting ROCK1-NOX1/2 and mitochondria superoxide signaling.

Abstract P079: Lymphatic Contraction Was Enhanced In Spontaneously Hypertensive Rats

Because lymph capillary network regulates interstitial electrolyte and volume balance, this system may function as regulating blood pressure (BP). Thus, changes in lymphatic activity can be expected to alter systemic BP. We recently reported that increasing BP caused lymphatic endothelial dysfunction via oxidative stress in hypertension. In this study, we examined lymphatic contractile function in thoracic duct from 10-14-week-old Wister-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). No distinct morphological difference was observed in thoracic duct isolated from WKY and SHR (n=4). Thoracic duct from SHR exhibited enhanced contractile response to serotonin (5-HT) or endothelin-1 (ET-1) compared to age-matched WKY (5-HT: 127.8±19.7% vs 53.6±10.3% of KCl-induced maximum contraction, p<0.05, n=5). The augmented contraction in SHR was diminished by fasudil, ROCK inhibitor (p<0.05, n=4-5). Consistent with this, increased phosphorylation of myosin phosphatase targeting protein (MYPT) was observed in SHR thoracic duct. Expression of ROCK1 or ROCK2 was not changed in SHR thoracic duct. Next we examined lymphatic contractile function in 4-week-old SHR showing normal BP. Contractile response to 5-HT or ET-1 was not enhanced in young SHR compared to age-matched WKY (n=4). To examine if lymphatic dysfunction was associated with increased BP, we treated 4-week-old SHR with antihypertensive drugs (hydrochlorothiazide and hydralazine) for 6 weeks. This treatment completely blocked elevation of systolic BP (SBP) in SHR (p<0.05, n=5), but did not prevent the augmentation of lymphatic contraction (5-HT: 99.0±7.2% vs 98.1±14.5%, n=5). Interestingly, treatment of young SHR with losartan (Angiotensin II type 1 receptor [AT1R] blocker) for 6 weeks ameliorated the augmented contraction (5-HT: 137.4±12.7% vs 77.9±8.8%, p<0.05, n=5), while this treatment scarcely diminished the increase in SBP (152.0±8.7 mmHg vs. 177.2±10.9 mmHg, p<0.05, n=5). We conclude that lymphatic contractile function was significantly enhanced in adult hypertensive SHR, which is mediated by RhoA/ROCK pathway thorough activation of AT1R. The increase in lymphatic constriction may be involved in increased BP in hypertension through decreased lymphatic compliance.

Tramadol enhances PGF2α-stimulated osteoprotegerin synthesis in osteoblasts

Osteoprotegerin (OPG) synthesized by osteoblasts is currently considered a crucial regulator to suppress the formation and function of osteoclasts. We previously showed that the synthesis of OPG is stimulated by prostaglandin F2α (PGF2α) in the involvement of p38 mitogen-activated protein kinase (MAPK), stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) and p44/p42 MAPK in osteoblast-like MC3T3-E1 cells. We also found that Rho-kinase is involved in the signaling of PGF2α upstream of p38 MAPK in these cells. Tramadol is widely used to treat chronic pain, such as low back pain associated with osteoporosis. We investigated whether or not tramadol affects the OPG release induced by PGF2α in osteoblast-like MC3T3-E1 cells. The levels of OPG in the conditioned medium were measured by an enzyme-linked immunosorbent assay. The mRNA expression of OPG was determined with real-time reverse transcription polymerase chain reaction. The phosphorylation of target protein was determined with a Western blot analysis. PGF2α induced the release and the mRNA expression of OPG, which tramadol significantly enhanced. Morphine, a selective μ-opioid receptor (MOR) agonist, also enhanced the PGF2α-induced OPG release. In addition, naloxone, a MOR antagonist, suppressed the enhancement by tramadol or morphine of the PGF2α-induced OPG synthesis. Tramadol upregulated the phosphorylation of SAPK/JNK and p38 MAPK stimulated by PGF2α but not that of p44/p42 MAPK or myosin phosphatase targeting protein (MYPT), a substrate of Rho-kinase. The inhibitors of both p38 MAPK and SAPK/JNK, SB203580 and SP600125, respectively, reduced the tramadol amplification of OPG release stimulated by PGF2α. The present results strongly suggest that tramadol enhances the synthesis of OPG stimulated by PGF2α through MOR in osteoblasts, and that the amplifying effect is exerted at upstream of p38 MAPK and SAPK/JNK but downstream of Rho-kinase.

Effect of lidocaine on Rho/ROCK signaling pathway during endotoxin-induced acute lung injury in rats

Objective To evaluate the effect of lidocaine on Ras homologue(Rho)/Rho kinase(ROCK)signaling pathway during endotoxin-induced lung injury(LI) in rats. Methods Forty SPF male Wistar rats, aged 5-8 weeks, weighing 200-250 g, were divided into 5 groups(n=8 each)using a random number table method: control group(group C), lipopolysaccharide(LPS)group(group LPS)and lidocaine at 3 different doses groups(L1-3 groups). LI was induced by intraperitoneal LPS 5 mg/kg(0.1 ml). The equal volume of normal saline was given intraperitoneally in group C. Lidocaine 2, 4 and 8 mg/kg was intraperitoneally injected at 1 h before LPS administration in L1-3 groups, respectively.The animals were sacrificed at 6 h after LPS or normal saline administration.Broncho-alveolar lavage fluid(BALF)was collected for determination of concentrations of interleukin-1 beta(IL-1β), IL-6 and tumor necrosis factor-alpha(TNF-α)(by enzyme-linked immunosorbent assay). The lung tissues were obtained for examination of the pathological changes which were scored and for measurement of the wet/dry weight ratio(W/D ratio)and activities of myeloperoxidase(MPO)and for determination of the expression of Rho, ROCK1, ROCK2, myosin phosphatase target protein 1(MYPT1), phosphorylated MYPT1(p-MYPT1)and ZO-1(by Western blot). The phosphorylation of MYPT1 was calculated. Results Compared with group C, the activity of MPO, lung injury score, W/D ratio and concentrations of IL-1β, IL-6 and TNF-α in BALF were significantly increased, the expression of Rho, ROCK1 and ROCK2 was up-regulated, the phosphorylation of MYPT-1 was increased, and the expression of ZO-1 was down-regulated in the other four groups(P<0.05). Compared with group LPS, the activity of MPO, lung injury score, W/D ratio and concentrations of IL-1β, IL-6 and TNF-α in BALF were significantly decreased, the expression of Rho, ROCK1 and ROCK2 was down-regulated, the phosphorylation of MYPT-1 was decreased, and the expression of ZO-1 was up-regulated in L1-L3 groups(P<0.05). Conclusion Lidocaine can inhibit activation of Rho/ROCK signaling pathway during endotoxin-induced LI in rats, and the effect may be related to the anti-inflammatory mechanism of lidocaine. Key words: Lidocaine; Rho factor; rho-Associated kinases; Endotoxemia; Respiratory distress syndrome, adult

Statin treatment before stroke reduces pro-inflammatory cytokine levels after stroke

ABSTRACTObjective: In this clinical case-control study, we investigated statin treatment in stroke patients on a range of inflammatory effectors in peripheral blood. We focus on RhoA GTPase and its downstream effectors as a future inflammatory target in stroke treatment.Methods: Data from 10 patients already on statins at stroke onset (Pre-S group) was compared with data from both 29 patients starting statin treatment right after stroke onset (Post-S group) and with 8 healthy controls. In T-cells isolated from stroke patients, we analyzed the activity of the main cytoskeletal regulator RhoA GTPase and its downstream effectors: rho-associated protein kinase (ROCK), myosin phosphatase targeting protein subunit 1 (pMYPT1), myosin light chain kinase (pMLC) and cofilin. In the blood samples, we further determined levels of 12 key plasma cytokines as well as C-reactive protein (CRP) and kallikrein.Results: Compared to healthy controls, the Post-S group achieved significantly higher RhoA and ROCK activities, while the Pre-S did not differ from controls. Levels of pMYPT1, pMLC and cofilin did not differ from controls in the Pre-S and Post-S groups. At day 90 after stroke, interferon γ and IL-18 were significantly increased in the Post-S group compared to the Pre-S group. We found a positive correlation between CRP and NIHSS, whereas kallikrein levels showed no correlation with NIHSS at any of the days.Conclusion: Stroke induces changes in the RhoA-ROCK pathway in T-cells. CRP and NIHSS score correlated positively in the study. Statins may have an anti-inflammatory effect as statin treatment before stroke reduces post-stroke pro-inflammatory levels. RhoA GTPase and its downstream effectors are possibly the key to improve statin treatment in stroke.

Oxidative stress and the altered reaction to it in Fabry disease: A possible target for cardiovascular-renal remodeling?

BackgroundFabry disease is characterized by deficient expression/activity of α-GalA with consequent lysosomal accumulation in various organs of its substrate Gb3. Despite enzyme replacement therapy, Fabry disease progresses with serious myocardial, cerebral and renal manifestations. Gb3 accumulation may induce oxidative stress (OxSt), production of inflammatory cytokines and reduction of nitric oxide, which may impact on Fabry disease’s clinical manifestations.MethodsOxSt status was characterized in 10 patients compared with 10 healthy subjects via protein expression of p22phox, subunit of NADH/NADPH oxidase, (Western blot), Heme oxygenase (HO)-1 levels (ELISA), antioxidant/anti-inflammatory, lipid peroxidation as malondialdehyde (MDA) production (colorimetric assay), phosphorylation state of Extracellular Signal Regulated Kinase (ERK)1/2 and Myosin Phosphatase Target Protein (MYPT)-1 (Western blot), marker of Rho kinase activation, both involved in OxSt signaling. Cardiac left ventricular (LV) mass was also evaluated (M-mode echocardiography).ResultsLV mass was higher in Fabry’s males (123.72±2.03SEM g/m2) and females (132.09±6.72g/m2). p22phox expression was also higher in patients (1.04±0.09 d.u. vs 0.54±0.05 d.u. p<0.01) as well as MDA levels (54.51±3.97 vs 30.05±7.11 nmol/mL p = 0.01) while HO-1 was reduced (8.84±0.79 vs 14.03±1.23 ng/mL, p<0.02). MYPT-1’s phosphorylation was increased in patients (0.52±0.11 d.u. vs 0.03±0.08 d.u., p<0.01) while phosphorylation of ERK1/2 was reduced (0.91±0.08 d.u. vs 1.53±0.17 d.u., p = 0.004).ConclusionsThis study documents OxSt activation and the altered reaction to it in Fabry patients. Cardiac remodeling, Rho kinase signaling activation and reduction of protective HO-1 might suggest that, in addition to enzyme replacement therapy, OxSt inhibition by either pharmacological or nutritional measures, is likely to prove useful for the prevention/treatment of Fabry patients’ cardiovascular-renal remodeling.

Effects of ripasudil, a ROCK inhibitor, on retinal edema and nonperfusion area in a retinal vein occlusion murine model

Rho-associated coiled-coil containing protein kinase (ROCK) inhibitors are used to treat glaucoma patients and have protective effects on ischemic states. However, it is poorly understood how the ROCK pathway affects the pathological signs of retinal vein occlusion (RVO). In this study, we evaluated the effects of ripasudil, a ROCK inhibitor, on a murine RVO model. In vivo, RVO was induced by retinal vein laser irradiation in mice, and evaluated with ripasudil. In vitro, the effects of ripasudil were examined on tight junction protein integrity in human retinal microvascular endothelial cells (HRMECs). Moreover, we investigated the expression level of the phosphorylated myosin phosphatase target protein (MYPT)-1 after administration of ripasudil. Ripasudil significantly prevented deterioration, such as retinal edema, reduced the size of the nonperfusion area, and improved retinal blood flow. Ripasudil treatment inhibited disintegration of ZO-1 in HRMECs. Administration of ripasudil suppressed retinal phosphorylation of MYPT-1 in a murine RVO model. These findings indicate that ripasudil might be as a possible therapeutic agent for RVO.

The α2 isoform Na,K-ATPase modulates contraction of rat mesenteric small artery via cSrc-dependent Ca2+ sensitization.

The Na,K-ATPase is involved in a large number of regulatory activities including cSrc-dependent signalling. Upon inhibition of the Na,K-ATPase with ouabain, cSrc activation is shown to occur in many cell types. This study tests the hypothesis that acute potentiation of agonist-induced contraction by ouabain is mediated through Na,K-ATPase-cSrc signalling-dependent sensitization of vascular smooth muscle cells to Ca2+ . Agonist-induced rat mesenteric small artery contraction was examined in vitro under isometric conditions and in vivo in anaesthetized rats. Arterial wall tension and [Ca2+ ]i in vascular smooth muscle cells were measured simultaneously. Changes in cSrc and myosin phosphatase targeting protein 1 (MYPT1) phosphorylation were analysed by Western blot. Protein expression was examined with immunohistochemistry. The α1 and α2 isoforms of the Na,K-ATPase were transiently downregulated by siRNA transfection in vivo. Ten micromolar ouabain, but not digoxin, potentiated contraction to noradrenaline. This effect was not endothelium-dependent. Ouabain sensitized smooth muscle cells to Ca2+ , and this was associated with increased phosphorylation of cSrc and MYPT1. Inhibition of tyrosine kinase by genistein, PP2 or pNaKtide abolished the potentiating effect of ouabain on arterial contraction and Ca2+ sensitization. Downregulation of the Na,K-ATPase α2 isoform made arterial contraction insensitive to ouabain and tyrosine kinase inhibition. Data suggest that micromolar ouabain potentiates agonist-induced contraction of rat mesenteric small artery via Na,K-ATPase-dependent cSrc activation, which increases Ca2+ sensitization of vascular smooth muscle cells by MYPT1 phosphorylation. This mechanism may be critical for acute control of vascular tone.

Chk1 modulates the interaction between myosin phosphatase targeting protein 1 (MYPT1) and protein phosphatase 1cβ (PP1cβ)

ABSTRACTPolo-like kinase 1 (Plk1) is an instrumental kinase that modulates many aspects of the cell cycle. Previous investigations have indicated that Plk1 is a target of the DNA damage response, and Plk1 inhibition is dependent on ATM/ATR and Chk1. But the exact mechanism remains elusive. In a proteomic screen to identify Chk1-interacting proteins, we found that myosin phosphatase targeting protein 1 (MYPT1) was present in the immunocomplex. MYPT1 is phosphorylated by CDK1, thus recruiting protein phosphatase 1β (PP1cβ) to dephosphorylate and inactivate Plk1. Here we identified that Chk1 directly interacts with MYPT1 and preferentially phosphorylates MYPT1 at Ser20, which is essential for MYPT1-PP1cβ interaction and subsequent Plk1 dephosphorylation. Phosphorylation of Ser20 is abolished during mitotic damage when Chk1 is inhibited. The degradation of MYPT1 is also regulated by Chk1 phosphorylation. Our results thus unveil the underlying machinery that attenuates Plk1 activity during mitotic damage through Chk1-induced phosphorylation of MYPT1.

TIMAP, the versatile protein phosphatase 1 regulator in endothelial cells.

Transforming growth factor (TGF)-β inhibited membrane associated protein, TIMAP, is the member of the myosin phosphatase targeting protein (MYPT) family of protein phosphatase 1 (PP1) regulatory subunits. The N-terminal part of TIMAP has a typical MYPT family structure with a sequence element called MyPhone (myosin phosphatase N-terminal element), a putative bipartite nuclear localization signal, a PP1 catalytic subunit binding motif, and five ankyrin repeats. The C-terminal half of TIMAP is intrinsically disordered, but ends with a functional CAAX box for lipid modification which allows localization of TIMAP at the plasma membrane. TIMAP is prenylated by farnesyl transferase with the contribution of the anchoring protein, RACK1 in the cytoplasm. The controlling effect of TIMAP on PP1 is moderated by PKA/GSK3β and PKC mediated phosphorylation of TIMAP, the sites are located in the disordered region of the protein. TIMAP is abundant in endothelial cells. A growing body of evidence attained through characterization of newly identified protein partners calls attention to its critical role in normal and pathological activities of the endothelium via regulation of PP1. TIMAP binds the non-integrin laminin receptor 1 and the endothelin converting enzyme 1, which may connect TIMAP to angiogenesis, tumor invasion and metastasis. Barrier protecting role of TIMAP was shown for pulmonary artery endothelial cells. ERM (ezrin-radixin-moesin) proteins, as potential in vivo PP1-TIMAP substrates, are critical targets in the barrier maintenance. TIMAP affects phosphorylation level and subcellular localization of merlin and eukaryotic elongation factor-1A1. Merlin is a key component of signaling pathways regulating cell proliferation, membrane domain formation and cell-cell junction organization. Noncanonical functions of the elongation factor include a role in organization of cytoskeleton dynamics and in apoptosis. The interacting/binding partners identified so far demonstrate a rather complex role of TIMAP in key functions of the endothelium offering TIMAP as a plausible target in pathological issues. © 2017 IUBMB Life, 69(12):918-928, 2017.

Abstract 124: RhoBTB1, a Novel PPARγ Target Gene, Rescues Hypertension and Vascular Dysfunction Caused by PPARγ Dysfunction

We reported that mice (S-DN) expressing dominant-negative peroxisome proliferator-activated receptor gamma (PPARγ) in smooth muscle cells (SMC) are hypertensive and exhibit impaired vascular relaxation due to increased RhoA/Rho kinase (ROCK) activity, and display reduced expression of a novel PPARγ target gene, RhoBTB1. We hypothesize that RhoBTB1 plays a protective role in vascular function and that the function of RhoBTB1 is disrupted in S-DN mice. To test this, we generated double transgenic mice (termed S-RhoBTB1) with tamoxifen-inducible, Cre-dependent expression of RhoBTB1 in SMC. S-RhoBTB1 mice were crossed with S-DN to produce mice (S-DN/S-RhoBTB1) in which tamoxifen-treatment (75 mg/kg, ip, 5 days) restored RhoBTB1 expression in aorta to normal. Thoracic aorta and basilar artery from S-DN showed severely impaired vasodilation to acetylcholine (ACh) and sodium nitroprusside, which was reversed by restoration of RhoBTB1 in SMC (Aorta, 46±5 vs 80±2% ACh-induced relaxation, p&lt;0.01, n=6-9). Replacement of RhoBTB1 also reversed the hypertensive phenotype and aortic stiffness observed in S-DN mice within 1 week of treatment (Radiotelemetry SBP, 141±6 vs 124±3 mmHg, p&lt;0.01, n=8-10; Aortic Pulse Wave Velocity, 3.8±0.2 vs 2.5±0.1 mm/ms, p&lt;0.01, n=11-13). Increased phosphorylation of myosin phosphatase targeting protein was preserved in both S-DN and S-DN/S-RhoBTB1 aorta, suggesting that restoration of RhoBTB1 did not affect increased RhoA/ROCK activity (p&lt;0.01, n=6). A phosphodiesterase (PDE) 5 inhibitor, Zaprinast improved vasodilation in S-DN (p&lt;0.01, n=8). Consistent with this, a cGMP analog that is resistant to PDE hydrolysis, 8-pCPT-cGMP, induced equivalent relaxation in S-DN and non-transgenic mice (n=4), while S-DN exhibited impaired relaxation induced by PDE-sensitive 8-Bromo-cGMP (p&lt;0.01, n=7). PDE activity was increased in S-DN aorta and was reduced to normal levels in S-DN/S-RhoBTB1 (p&lt;0.01, n=6). We conclude: a) loss of RhoBTB1 function explains the vascular dysfunction and hypertension observed in response to interference with PPARγ in smooth muscle, b) DN PPARγ in SMC causes vascular dysfunction via promoting PDE activity, and c) restoration of RhoBTB1 in SMC facilitates vasodilatation by normalizing PDE activity.

Silencing of galectin-1 inhibits retinal neovascularization and ameliorates retinal hypoxia in a murine model of oxygen-induced ischemic retinopathy

Aberrant neovascularization is a consequence of inappropriate angiogenic signaling and contributes to several diseases. Although many regulators of pathogenic angiogenesis have been identified, the understanding of this process remains incomplete. Galectin-1 (Gal-1), as a homodimeric protein with a single carbohydrate-recognition domain, is implicated in several pathologic processes, including angiogenesis; however, its involvement in retinal neovascularization (RNV) remains unknown. Here, we investigated the anti-angiogenic effect of silencing Gal-1 through intravitreal injection in a mouse model of oxygen-induced retinopathy (OIR). Our results revealed that Gal-1 was overexpressed and closely related to retinal neo-vessels in OIR retinas. After silencing Gal-1 via intravitreal injection of adenoviral-Gal-1-RNA interference (Ad-Gal-1-RNAi), RNV and retinal hypoxia were significantly attenuated, indicating the anti-angiogenic effect of Gal-1 inhibition. Western blot analysis and real-time polymerase chain reaction indicated that the expression of both neuropilin-1 (Nrp-1) and B cell lymphoma-2 (Bcl-2) decreased after intravitreal injection of Ad-Gal-1-RNAi, implying the possible involvement of Nrp-1 and Bcl-2 in Gal-1-related angiogenic processes. Additionally, whole-mount fluorescence and hematoxylin and eosin staining showed that intravitreal injection of Ad-Gal-1-RNAi did not significantly disrupt the retinal vasculature and neuronal structure of room air mice. Moreover, Ad-Gal-1-RNAi transfer promoted retinal vascular sprouting and increased retinal vascular perfusion, likely through decreased phosphorylation of myosin phosphatase target protein-1. Collectively, our results demonstrated that Gal-1 functions as an important regulator in RNV and offers a promising strategy for the treatment of RNV diseases, such as proliferative diabetic retinopathy and retinopathy of prematurity.

Effect of inhalation of hydrogen gas on Rho/ROCK pathway in lung tissues of septic mice with acute lung injury

Objective To evaluate the effect of inhalation of hydrogen gas (H2) on Rho/Rho kinase (ROCK) pathway in lung tissues of septic mice with acute lung injury. Methods Forty male C57BL/6 mice, weighing 20-25 g, aged 6 weeks, were randomly divided into 4 groups (n=10 each) using a random number table: sham operation group (group Sh), sham operation+ inhalation of H2 group (group H2), sepsis group (group S), and sepsis+ inhalation of H2 group (group S+ H2). Sepsis was produced by cecal ligation and puncture (CLP). Both H2 and S+ H2 groups inhaled 2% H2 for 1 h starting from 1 and 6 h after CLP.The mice in each group were sacrificed at 24 h after CLP.The bronchoalveolar lavage fluid (BALF) was collected for determination of protein concentrations, polymorphonuclear neutrophil (PMN) count, and concentrations of tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) (by enzyme-linked immunosorbent assay). The lung tissues were obtained for examination of the pathological changes which were scored and for determination of the wet/dry weight ratio (W/D ratio), activities of myeloperoxidase (MPO) and superoxide dismutase (SOD), malonaldehyde (MDA) level, the expression of Rho, ROCK1, ROCK2 and activated caspase-3, and phosphorylation of myosin phosphatase target protein 1 (MYPT-1) (by Western blot). Results Compared with group Sh, the concentrations of protein, PMN count, and concentrations of TNF-α and IL-1β in BALF, lung injury score, W/D ratio, and levels of MPO and MDA in lung tissues were significantly increased, the activity of SOD in lung tissues was significantly decreased, the expression of Rho, ROCK1, ROCK2 and activated caspase-3 was significantly up-regulated, and the phosphorylation of MYPT-1 in lung tissues was significantly increased in S and S+ H2 groups (P 0.05). Compared with group S, the concentrations of protein, PMN count, and concentrations of TNF-α and IL-1β in BALF, lung injury score, W/D ratio, and levels of MPO and MDA in lung tissues were significantly decreased, the activity of SOD in lung tissues was significantly increased, the expression of Rho, ROCK1, ROCK2 and activated caspase-3 in lung tissues was significantly down-regulated, and the phosphorylation of MYPT-1 in lung tissues was significantly decreased in group S+ H2 (P<0.05). Conclusion The mechanism by which inhalation of H2 attenuates acute lung injury is related to inhibition of Rho/ROCK pathway activation in lung tissues of septic mice. Key words: Hydrogen; Sepsis; Respiratory distress syndrome, adult; Rho factor; Rho-associated kinases

AMA0428, A Potent Rock Inhibitor, Attenuates Early and Late Experimental Diabetic Retinopathy

ABSTRACTPurpose: Diabetic retinopathy (DR) is characterized by an early stage of inflammation and vessel leakage, and an advanced vasoproliferative stage. Also, neurodegeneration might play an important role in disease pathogenesis. The aim of this study was to investigate the effect of the Rho kinase (ROCK) inhibitor, AMA0428, on these processes.Methods: The response to ROCK inhibition by AMA0428 (1 µg) was studied in vivo using the murine model for streptozotocin (STZ)-induced diabetes, focusing on early non-proliferative DR features and the oxygen-induced retinopathy (OIR) model to investigate proliferative DR. Intravitreal (IVT) administration of AMA0428 was compared with murine anti-VEGF-R2 antibody (DC101, 6.2 µg) and placebo (H2O/PEG; 1C8). Outcome was assessed by analyzing leukostasis using fluorescein isothiocyanate coupled concanavalin A (FITC-ConA) and vessel leakage (bovine serum albumin conjugated with fluorescein isothiocyanate; FITC-BSA)/neovascularization and neurodegeneration by immunohistological approaches (hematoxylin and eosin (H&E), terminal deoxynucleotidyl transferase–mediated biotinylated UTP nick end labeling (TUNEL), Brn3a). ELISA and Western blotting were employed to unravel the consequences of ROCK inhibition (1 µM AMA0428) on myosin phosphatase target protein (MYPT)-1 phosphorylation, endothelial nitric oxide synthase (eNOS) phosphorylation, and vascular endothelial growth factor (VEGF) levels in retinas of diabetic mice, on NF-κβ activity and ICAM-1 expression in endothelial cells (ECs).Results: In vivo, AMA0428 significantly reduced vessel leakage and neovascularization, respectively, in the STZ and OIR model, comparable to DC101 therapy. Additionally, the ROCK inhibitor decreased neurodegeneration in both models and inhibited leukostasis by 30% (p < 0.05) in the STZ model (p < 0.05), while DC101 had no positive effect on the outcome of these latter processes. ROCK activity was upregulated in the diabetic retina and AMA0428 administration resulted in decreased phospho-MYPT-1, enhanced phospho-eNOS, and reduced VEGF levels. In vitro, AMA0428 interfered with NF-κβ activity, thereby inhibiting ICAM-1 expression in ECs.Conclusions: Targeting ROCK with AMA0428 effectively attenuated outcome in an early DR model (STZ) and a late vasoproliferative retinopathy model (OIR). These findings make AMA0428 a promising candidate with an additional anti-inflammatory and neuroprotective benefit for DR patients, as compared with anti-VEGF treatment.

Vascular Normalization by ROCK Inhibitor: Therapeutic Potential of Ripasudil (K-115) Eye Drop in Retinal Angiogenesis and Hypoxia.

In this study, we investigated the therapeutic potential of a Rho-associated coiled-coil-containing protein kinase (ROCK) inhibitor ripasudil (K-115) eye drop on retinal neovascularization and hypoxia. In vitro, human retinal microvascular endothelial cells (HRMECs) were pretreated with ripasudil and then stimulated with VEGF. ROCK activity was evaluated by phosphorylation of myosin phosphatase target protein (MYPT)-1. Endothelial migration and cell viability were assessed by cell migration and MTT assay, respectively. The concentration of ripasudil in the retina was measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In vivo, normal saline, 0.4%, or 0.8% ripasudil were administered three times a day to mice with oxygen-induced retinopathy (OIR). The areas of neovascularization and avascular retina were also quantified with retinal flat-mounts at postnatal day (P) 15, P17, or P21. The retinal hypoxic area was evaluated using hypoxia-sensitive drug pimonidazole by immunohistochemistry at P17. The vascular normalization was also evaluated by immunohistochemistry at P17. Ripasudil but not fasudil significantly reduced VEGF-induced MYPT-1 phosphorylation in HRMECs at 30 μmol/L. Ripasudil significantly inhibited VEGF-induced HRMECs migration and proliferation. The concentration of ripasudil in the retina was 3.8 to 10.4 μmol/L and 6.8 to 14.8 μmol/L after 0.4% and 0.8% ripasudil treatment, respectively. In the 0.4% and 0.8% ripasudil treated OIR mice, the areas of neovascularization as well as avascular area in the retina was significantly reduced compared with those of saline-treated mice at P17 and P21. Pimonidazole staining revealed that treatment with 0.4% and 0.8% ripasudil significantly inhibited the increase in the hypoxic area compared with saline. 0.8% ripasudil could cause intraretinal vascular sprouting and increase retinal vascular perfusion. Novel ROCK inhibitor ripasudil eye drop has therapeutic potential in the treatment of retinal hypoxic neovascular diseases via antiangiogenic effects as well as vascular normalization.

Erectile dysfunction in heart failure rats is associated with increased neurogenic contractions in cavernous tissue and internal pudendal artery

The rates of erectile dysfunction (ED) in heart failure (HF) are extremely high. This study tested the hypothesis that rats with HF display ED and that HF leads to increased sympathetic-mediated contractile tone of the cavernous tissue and/or internal pudendal arteries (IPA) as potential mechanisms contributing to ED. HF was induced in Wistar rats by ligation of the left anterior descending coronary artery. Changes in the ratio of intracavernosal pressure/mean arterial pressure (ICP/MAP) after electrical stimulation of major pelvic ganglion were determined in vivo. Cavernosal and IPA contractions were induced by electric field stimulation (EFS) and phenylephrine. RhoA, Rho kinase 2 (ROCK 2) and myosin phosphatase target protein 1 (MYPT-1) protein expression and phosphorylation levels were also determined. HF rats display impaired erectile function represented by decreased ICP/MAP responses. EFS-mediated contractions were increased by HF in cavernous tissue and IPA. Contractions induced by phenylephrine were increased in cavernous tissue of HF rats, but decreased in IPA rings. Moreover, HF decreased RhoA protein expression, but increased ROCK 2 and MYPT-1 phosphorylation levels in cavernous tissue. In conclusion, rats with HF induced by myocardial infarction display ED in vivo and increased sympathetic-mediated contractile responses in cavernous tissue and IPA. Increased sympathetic-mediated contractile responses were associated with increased ROCK 2 and MYPT-1 phosphorylation in cavernosal tissue, suggesting the involvement of ROCK signaling pathway in ED genesis. Our findings suggest new mechanisms linking HF to ED, providing potential therapeutic targets for treating ED associated to HF.

Abstract 12454: Mitochondrial Transcription Factor 2B as a Mediator of Mitochondrial Retrograde Signaling and Endothelial Cell Shape

Mitochondrial dysfunction, such as observed in endothelial cells, has been implicated in various cardiovascular diseases including, hypertension and atherosclerosis. Mitochondrial transcription factor 2B (TFB2M) is an essential component to maintain proper transcriptional and functional control of mitochondrial DNA. As well, elongation of endothelial cells is a characteristic of atheroprotective regions within the vasculature, and the relationship between the mitochondria and EC shape is currently unknown. Additionally, recent interest has been focused on mechanisms by which the mitochondria may signal to the nucleus to affect cell function. The aim of our study is to investigate the hypothesis that TFB2M has a novel role in enhancing endothelial function. Human umbilical vein endothelial cells (HUVECs) were harvested 72 hours after adenoviral transduction with TFB2M (100 moi). HUVECs transduced with TFB2M showed an elongated cell morphology when compared to GFP control. To further investigate the effect of TFB2M on regulating mitochondrial function and cell shape, immunoblotting was carried out for markers involved in mitochondrial function/dynamics and markers indicative of cytoskeleton reorganization. TFB2M transduction resulted in increased expression of mitochondrial biogenesis marker VDAC (2.6 fold increase), mitochondrial fusion protein MFN2 (2.1 fold increase), and phosphorylated myosin phosphatase targeting protein MYPT1 at Thr850 (2.2 fold increase, p &lt; 0.05 for all proteins). Additionally, fluorescence microscopy showed enhanced mitochondrial fluorescence in TFB2M transduced cells using mitotracker red staining (3.5 fold increase, p &lt; 0.001). These data indicate that TFB2M has a previously undiscovered function contributing to altered EC function and shape, potentially through a novel mitochondrial retrograde signaling mechanism. Further research will focus on distinguishing the exact mechanisms culminating in a protective EC phenotype and the beneficial role of endothelial TFB2M-mediated enhanced mitochondrial function in the treatment of EC dysfunction associated with various cardiovascular diseases.

Abstract P122: Mitochondrial Transcription Factor 2B Regulates Endothelial Cell Morphology

Mitochondrial dysfunction, such as observed in endothelial cells, has been implicated in various cardiovascular diseases including, hypertension and atherosclerosis. Mitochondrial transcription factor 2B (TFB2M) is an essential component to maintain proper transcriptional and functional control of mitochondrial DNA. As well, elongation of endothelial cells is a characteristic of atheroprotective regions within the vasculature, and the relationship between the mitochondria and EC shape is currently unknown. The aim of our study is to investigate the hypothesis that TFB2M has a novel role in enhancing endothelial function. Human umbilical vein endothelial cells (HUVECs) were harvested 72 hours after adenoviral transduction with TFB2M (100 moi). HUVECs transduced with TFB2M showed an elongated cell morphology when compared to GFP control. To further investigate the effect of TFB2M on regulating mitochondrial function and cell shape, immunoblotting was carried out for markers involved in mitochondrial function/dynamics and markers indicative of cytoskeleton reorganization. TFB2M transduction resulted in increased expression of mitochondrial biogenesis marker VDAC (2.6 fold increase), mitochondrial fusion protein MFN2 (2.1 fold increase), and phosphorylated myosin phosphatase targeting protein MYPT1 at Thr850 (2.2 fold increase, p &lt; 0.05 for all proteins). Additionally, fluorescence microscopy showed enhanced mitochondrial fluorescence in TFB2M transduced cells using mitotracker red staining (3.5 fold increase, p &lt; 0.001). These data indicate that TFB2M has a previously undiscovered function contributing to altered EC function and shape, potentially through a novel mitochondrial retrograde signaling mechanism. Further research will focus on distinguishing the exact mechanisms culminating in a protective EC phenotype and the beneficial role of endothelial TFB2M-mediated enhanced mitochondrial function in the treatment of EC dysfunction associated with various cardiovascular diseases.