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Nelson MR, Zhang X, Podgaetz E, Wang X, Zhang Q, Pan Z, Spechler SJ, Souza RF. Th2 cytokine signaling through IL-4Rα increases eotaxin-3 secretion and tension in human esophageal smooth muscle. Am J Physiol Gastrointest Liver Physiol 2024; 326:G38-G52. [PMID: 37933466 DOI: 10.1152/ajpgi.00155.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/24/2023] [Accepted: 10/24/2023] [Indexed: 11/08/2023]
Abstract
In esophageal epithelial cells in eosinophilic esophagitis (EoE), Th2 cytokines (IL-4, IL-13) signal through IL-4Rα, activating JAK to increase eotaxin-3 secretion, which draws eosinophils into the mucosa. We explored whether Th2 cytokines also might stimulate eotaxin-3 secretion and increase tension in esophageal smooth muscle (ESM), which might impair esophageal distensibility, and whether those events could be blocked by proton pump inhibitors (PPIs) or agents that disrupt IL-4Rα signaling. We established human ESM cell cultures from organ donors, characterizing Th2 cytokine receptor and P-type ATPase expression by qPCR. We measured Th2 cytokine-stimulated eotaxin-3 secretion by enzyme-linked immunosorbent assay (ELISA) and ESM cell tension by gel contraction assay, before and after treatment with omeprazole, ruxolitinib (JAK inhibitor), or IL-4Rα blocking antibody. CPI-17 (inhibitor of a muscle-relaxing enzyme) effects were studied with CPI-17 knockdown by siRNA or CPI-17 phospho(T38A)-mutant overexpression. ESM cells expressed IL-4Rα and IL-13Rα1 but only minimal H+-K+-ATPase mRNA. Th2 cytokines increased ESM eotaxin-3 secretion and tension, effects blocked by ruxolitinib and IL-4Rα blocking antibody but not consistently blocked by omeprazole. IL-13 increased ESM tension by increasing CPI-17 expression and phosphorylation, effects blocked by CPI-17 knockdown. Blocking IL-4Rα decreased IL-13-stimulated eotaxin-3 secretion, CPI-17 expression, and tension in ESM. Th2 cytokines increase ESM eotaxin-3 secretion and tension via IL-4Rα signaling that activates CPI-17. Omeprazole does not reliably inhibit this process, but IL-4Rα blocking antibody does. This suggests that ESM eosinophilia and impaired esophageal distensibility might persist despite elimination of mucosal eosinophils by PPIs, and IL-4Rα blocking agents might be especially useful in this circumstance.NEW & NOTEWORTHY We have found that Th2 cytokines increase eotaxin-3 secretion and tension in esophageal smooth muscle (ESM) cells via IL-4Rα signaling. Unlike esophageal epithelial cells, ESM cells do not express H+-K+-ATPase, and omeprazole does not inhibit their cytokine-stimulated eotaxin-3 secretion or tension. An IL-4Rα blocking antibody reduces both eotaxin-3 secretion and tension induced by Th2 cytokines in ESM cells, suggesting that an agent such as dupilumab might be preferred for patients with EoE with esophageal muscle involvement.
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Affiliation(s)
- Melissa R Nelson
- Department of Medicine, Center for Esophageal Diseases, Baylor University Medical Center and Center for Esophageal Research, Baylor Scott and White Research Institute, Dallas, Texas, United States
| | - Xi Zhang
- Department of Medicine, Center for Esophageal Diseases, Baylor University Medical Center and Center for Esophageal Research, Baylor Scott and White Research Institute, Dallas, Texas, United States
| | - Eitan Podgaetz
- Center for Thoracic Surgery, Center for Esophageal Diseases, Baylor University Medical Center and Center for Esophageal Research, Baylor Scott and White Research Institute, Dallas, Texas, United States
| | - Xuan Wang
- Biostatistics Core, Baylor Scott and White Research Institute, Dallas, Texas, United States
| | - Qiuyang Zhang
- Department of Medicine, Center for Esophageal Diseases, Baylor University Medical Center and Center for Esophageal Research, Baylor Scott and White Research Institute, Dallas, Texas, United States
| | - Zui Pan
- College of Nursing and Health Innovation, The University of Texas at Arlington, Arlington, Texas, United States
| | - Stuart Jon Spechler
- Department of Medicine, Center for Esophageal Diseases, Baylor University Medical Center and Center for Esophageal Research, Baylor Scott and White Research Institute, Dallas, Texas, United States
| | - Rhonda F Souza
- Department of Medicine, Center for Esophageal Diseases, Baylor University Medical Center and Center for Esophageal Research, Baylor Scott and White Research Institute, Dallas, Texas, United States
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Nunes KP, Webb RC. New insights into RhoA/Rho-kinase signaling: a key regulator of vascular contraction. Small GTPases 2020; 12:458-469. [PMID: 32970516 DOI: 10.1080/21541248.2020.1822721] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
While Rho-signalling controlling vascular contraction is a canonical mechanism, with the modern approaches used in research, we are advancing our understanding and details into this pathway are often uncovered. RhoA-mediated Rho-kinase is the major regulator of vascular smooth muscle cells and a key player manoeuvring other functions in these cells. The discovery of new interactions, such as oxidative stress and hydrogen sulphide with Rho signalling are emerging addition not only in the physiology of the smooth muscle, but especially in the pathophysiology of vascular diseases. Likewise, the interplay between ageing and Rho-kinase in the vasculature has been recently considered. Importantly, in smooth muscle contraction, this pathway may also be affected by sex hormones, and consequently, sex-differences. This review provides an overview of Rho signalling mediating vascular contraction and focuses on recent topics discussed in the literature affecting this pathway such as ageing, sex differences and oxidative stress.
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Affiliation(s)
- Kenia Pedrosa Nunes
- Laboratory of Vascular Physiology, Department of Biomedical and Chemical Engineering and Sciences, Florida Institute of Technology, Melbourne, FL, USA
| | - R Clinton Webb
- Department of Cell Biology and Anatomy, University of South Carolina, Columbia, SC, USA
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Signaling pathways underlying changes in the contractility of the stomach fundus smooth muscle in diabetic rats. Arch Pharm Res 2020; 43:666-675. [PMID: 32607942 DOI: 10.1007/s12272-020-01244-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 06/25/2020] [Indexed: 10/24/2022]
Abstract
Dysfunction of gastrointestinal (GI) motility is a common complication in patients with diabetes mellitus (DM). Studies related to changes in fundus contraction induced by inhibitors in DM are not well known. Therefore, this study aimed to investigate the signaling pathways involved in the changes in the contraction of fundus smooth muscle obtained from control and DM rats. DM was induced by injecting streptozotocin (65 mg/kg) into Sprague-Dawley rats. The rats were sacrificed after 14 days. Fundus smooth muscle contraction was stimulated using electrical field stimulation (amplitude, 50 V; duration, 1 min; frequency, 2-20 Hz) and acetylcholine (0.1 mM). The inhibitor-mediated cell membrane was pre-treated with atropine, verapamil, methysergide, ketanserin, ondansetron, and GR 113808. Inhibitors related to intracellular signaling, such as U73122, chelerythrine, L-NNA, were also used. ML-9 and Y-27632 were identified as inhibitors of factors of myosin light chain (MLC). The contractility was observed to be lower in the DM group than in the control group. Further, the activities of phospholipase C (PLC), protein kinase C (PKC), and myosin light chain kinase (MLCK) were decreased in the DM group. DM reduced the activity of PLC, PKC, and MLCK, which resulted in a decrease in the contractility of the fundus smooth muscle. Therefore, our results present the mechanism of this DM-mediated GI disorder.
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Qiu JY, Ma LQ, Liu BB, Zhang WJ, Liu MS, Wang GG, Zhao XX, Luo X, Wang Q, Xu H, Zang DA, Shen J, Peng YB, Zhao P, Xue L, Yu MF, Chen W, Dai J, Liu QH. Folium Sennae and emodin reverse airway smooth muscle contraction. Cell Biol Int 2020; 44:1870-1880. [PMID: 32437058 DOI: 10.1002/cbin.11393] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 04/26/2020] [Accepted: 05/18/2020] [Indexed: 11/09/2022]
Abstract
The objective of this project was to find a bronchodilatory compound from herbs and clarify the mechanism. We found that the ethanol extract of Folium Sennae (EEFS) can relax airway smooth muscle (ASM). EEFS inhibited ASM contraction, induced by acetylcholine, in mouse tracheal rings and lung slices. High-performance liquid chromatography assay showed that EEFS contained emodin. Emodin had a similar reversal action. Acetylcholine-evoked contraction was also partially reduced by nifedipine (a selective inhibitor of L-type voltage-dependent Ca2+ channels, LVDCCs), YM-58483 (a selective inhibitor of store-operated Ca2+ entry, SOCE), as well as Y-27632 (an inhibitor of Rho-associated protein kinase). In addition, LVDCC- and SOCE-mediated currents and cytosolic Ca2+ elevations were inhibited by emodin. Emodin reversed acetylcholine-caused increases in phosphorylation of myosin phosphatase target subunit 1. Furthermore, emodin, in vivo, inhibited acetylcholine-induced respiratory system resistance in mice. These results indicate that EEFS-induced relaxation results from emodin inhibiting LVDCC, SOCE, and Ca2+ sensitization. These findings suggest that Folium Sennae and emodin may be new sources of bronchodilators.
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Affiliation(s)
- Jun-Ying Qiu
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Li-Qun Ma
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Bei-Bei Liu
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Wen-Jing Zhang
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Meng-Su Liu
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Ge-Ge Wang
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Xiao-Xue Zhao
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Xi Luo
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Qian Wang
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Hao Xu
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Dun-An Zang
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Jinhua Shen
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Yong-Bo Peng
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Ping Zhao
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Lu Xue
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Meng-Fei Yu
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Weiwei Chen
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Jiapei Dai
- Wuhan Institute for Neuroscience and Engineering, South-Central University for Nationalities, Wuhan, China
| | - Qing-Hua Liu
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area and Hubei Medical Biology International Science and Technology Cooperation Base, Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
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Improving Small Intestinal Motility in Experimental Acute Necrotising Pancreatitis by Modulating the CPI-17/MLCP Pathway Using Chaiqin Chengqi Decoction. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2020; 2020:9189457. [PMID: 32104199 PMCID: PMC7035521 DOI: 10.1155/2020/9189457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 12/09/2019] [Indexed: 02/08/2023]
Abstract
Protein kinase C-potentiated inhibitor protein of 17 kDa (CPI-17), a specific inhibitor of myosin light-chain phosphatase (MLCP) regulated by proinflammatory cytokines, is central for calcium sensitisation. We investigated the effects of chaiqin chengqi decoction (CQCQD) on the CPI-17/MLCP pathway in the small intestinal smooth muscle cells (SMCs) and strips (SMS) in an AP model. Necrotising AP was induced in rats by intraperitoneal injections (IPI) of L-ornithine (3.0 g/kg, pH 7.0; hourly × 2) at 1 hour apart; controls received saline. In treatment groups, carbachol (CCh; 60 μg/kg, IPI) or CQCQD (20 g/kg; 2-hourly × 3, intragastric) was administered. The necrotising AP model was associated with systemic inflammation (serum IL-1β and TNF-α) and worsened jejunum histopathology and motility (serum vasoactive intestinal peptide and intestinal fatty acid-binding protein) as the disease progressed. There was decreased intracellular calcium concentration ([Ca2+]i) SMCs. Contractile function of isolated SMCs was reduced and associated with down-regulated expression of key mRNAs and proteins of the CPI-17/MLCP pathway as well as increased IL-1β and TNF-α. CQCQD and CCh significantly reversed these changes and the disease severity. These data suggest that CQCQD can improve intestinal motility by modulating the CPI-17/MLCP pathway in small intestinal smooth muscle during AP.
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6
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Camilleri M, Sandler RS, Peery AF. Etiopathogenetic Mechanisms in Diverticular Disease of the Colon. Cell Mol Gastroenterol Hepatol 2019; 9:15-32. [PMID: 31351939 PMCID: PMC6881605 DOI: 10.1016/j.jcmgh.2019.07.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 07/17/2019] [Accepted: 07/18/2019] [Indexed: 02/08/2023]
Abstract
This article reviews epidemiological evidence of heritability and putative mechanisms in diverticular disease, with greatest attention to 3 recent studies of genetic associations with diverticular disease based on genome-wide or whole-genome sequencing studies in large patient cohorts. We provide an analysis of the biological plausibility of the significant associations with gene variants reported and highlight the relevance of ANO1, CPI-17 (aka PPP1R14A), COLQ6, COL6A1, CALCB or CALCA, COL6A1, ARHGAP15, and S100A10 to colonic neuromuscular function and tissue properties that may result in altered compliance and predispose to the development of diverticular disease. Such studies also identify candidate genes for future studies.
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Affiliation(s)
- Michael Camilleri
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
| | - Robert S Sandler
- Center for Gastrointestinal Biology and Disease, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Anne F Peery
- Center for Gastrointestinal Biology and Disease, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
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7
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Paracetamol inhibits Ca 2+ permeant ion channels and Ca 2+ sensitization resulting in relaxation of precontracted airway smooth muscle. J Pharmacol Sci 2019; 142:60-68. [PMID: 31843508 DOI: 10.1016/j.jphs.2019.07.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 06/27/2019] [Accepted: 07/17/2019] [Indexed: 12/24/2022] Open
Abstract
The purpose of this study was to screen a bronchodilator from old drugs and elucidate the underlying mechanism. Paracetamol (acetaminophen) is a widely used analgesic and antipyretic drug. It has been reported that it inhibits the generation of prostaglandin and histamine, which play roles in asthma. These findings led us to explore whether paracetamol could be a potential bronchodilator. Paracetamol inhibited high K+- and acetylcholine (ACH)-induced precontraction of mouse tracheal and bronchial smooth muscles. Moreover, the ACH-induced contraction was partially inhibited by nifedipine (selective blocker of LVDCCs), YM-58483 (selective inhibitor of store-operated Ca2+ entry (SOCE), canonical transient receptor potential 3 (TRPC3) and TRPC5 channels) and Y-27632 (selective blocker of ROCK, a linker of the Ca2+ sensitization pathway). In single airway smooth muscle cells, paracetamol blocked the currents sensitive to nifedipine and YM-58483, and inhibited intracellular Ca2+ increases. In addition, paracetamol inhibited ACH-induced phosphorylation of myosin phosphatase target subunit 1 (MYPT1, another linker of the Ca2+ sensitization pathway). Finally, in vivo paracetamol inhibited ACH-induced increases of mouse respirator system resistance. Collectively, we conclude that paracetamol inhibits ASM contraction through blocking LVDCCs, SOCE and/or TRPC3 and/or TRPC5 channels, and Ca2+ sensitization. These results suggest that paracetamol might be a new bronchodilator.
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Generation of Spontaneous Tone by Gastrointestinal Sphincters. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019. [PMID: 31183822 DOI: 10.1007/978-981-13-5895-1_2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
An important feature of the gastrointestinal (GI) muscularis externa is its ability to generate phasic contractile activity. However, in some GI regions, a more sustained contraction, referred to as "tone," also occurs. Sphincters are muscles oriented in an annular manner that raise intraluminal pressure, thereby reducing or blocking the movement of luminal contents from one compartment to another. Spontaneous tone generation is often a feature of these muscles. Four distinct smooth muscle sphincters are present in the GI tract: the lower esophageal sphincter (LES), the pyloric sphincter (PS), the ileocecal sphincter (ICS), and the internal anal sphincter (IAS). This chapter examines how tone generation contributes to the functional behavior of these sphincters. Historically, tone was attributed to contractile activity arising directly from the properties of the smooth muscle cells. However, there is increasing evidence that interstitial cells of Cajal (ICC) play a significant role in tone generation in GI muscles. Indeed, ICC are present in each of the sphincters listed above. In this chapter, we explore various mechanisms that may contribute to tone generation in sphincters including: (1) summation of asynchronous phasic activity, (2) partial tetanus, (3) window current, and (4) myofilament sensitization. Importantly, the first two mechanisms involve tone generation through summation of phasic events. Thus, the historical distinction between "phasic" versus "tonic" smooth muscles in the GI tract requires revision. As described in this chapter, it is clear that the unique functional role of each sphincter in the GI tract is accompanied by a unique combination of contractile mechanisms.
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Sung TS, Lu H, Sung J, Yeom JH, Perrino BA, Koh SD. The functional role of protease-activated receptors on contractile responses by activation of Ca 2+ sensitization pathways in simian colonic muscles. Am J Physiol Gastrointest Liver Physiol 2018; 315:G921-G931. [PMID: 30260688 PMCID: PMC6336947 DOI: 10.1152/ajpgi.00255.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
It has been known that activation of protease-activated receptors (PARs) affects gastrointestinal motility. In this study, we tested the effects of PAR agonists on electrical and contractile responses and Ca2+ sensitization pathways in simian colonic muscles. The Simian colonic muscle was initially hyperpolarized by PAR agonists. After the transient hyperpolarization, simian colonic muscle repolarized to the control resting membrane potential (RMP) without a delayed depolarization. Apamin significantly reduced the initial hyperpolarization, suggesting that activation of small conductance Ca2+-activated K+ (SK) channels is involved in the initial hyperpolarization. In contractile experiments, PAR agonists caused an initial relaxation followed by an increase in contractions. These delayed contractile responses were not matched with the electrical responses that showed no after depolarization of the RMP. To investigate the possible involvement of Rho-associated protein kinase 2 (ROCK) pathways in the PAR effects, muscle strips were treated with ROCK inhibitors, which significantly reduced the PAR agonist-induced contractions. Furthermore, PAR agonists increased MYPT1 phosphorylation, and ROCK inhibitors completely blocked MYPT1 phosphorylation. PAR agonists alone had no effect on CPI-17 phosphorylation. In the presence of apamin, PAR agonists significantly increased CPI-17 phosphorylation, which was blocked by protein kinase C (PKC) inhibitors suggesting that Ca2+ influx is increased by apamin and is activating PKC. In conclusion, these studies show that PAR activators induce biphasic responses in simian colonic muscles. The initial inhibitory responses by PAR agonists are mainly mediated by activation of SK channels and delayed contractile responses are mainly mediated by the CPI-17 and ROCK Ca2+ sensitization pathways in simian colonic muscles. NEW & NOTEWORTHY In the present study, we found that the contractile responses of simian colonic muscles to protease-activated receptor (PAR) agonists are different from the previously reported contractile responses of murine colonic muscles. Ca2+ sensitization pathways mediate the contractile responses of simian colonic muscles to PAR agonists without affecting the membrane potential. These findings emphasize novel mechanisms of PAR agonist-induced contractions possibly related to colonic dysmotility in inflammatory bowel disease.
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Affiliation(s)
- Tae Sik Sung
- 1Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Hongli Lu
- 2Department of Physiology, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Juno Sung
- 1Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Jong Hoon Yeom
- 3Department of Anesthesiology and Pain Medicine, Hanyang University, Seoul, Republic of Korea
| | - Brian A. Perrino
- 1Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sang Don Koh
- 1Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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Liao Q, Yan J, Zhou Z, Luo J, Han Q, Zhang Q, Chen R. Relationship between uterine smooth muscular CPI-17-signal pathway-mediated Ca 2+ sensitivity changes and uterine atony-induced postpartum haemorrhage. J OBSTET GYNAECOL 2018; 39:302-307. [PMID: 30428734 DOI: 10.1080/01443615.2018.1504206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This study aimed to investigate the changes of protein kinase C (PKC)-potentiated phosphatase inhibitor of 17 ku (CPI-17) expression, PKC activity and Rho kinase activity in the maternal uterine smooth muscle (USM), and their roles in the occurrence of uterine atony-induced postpartum haemorrhage (UAI-PPH). Sixty primiparaes who had a caesarean section performed were divided into the case group (with UAI-PPH) and the control group (the uterine contraction was good, without the PPH). The USM-p-CPI-17 (Thr38) protein levels, the activities of PKC and Rho kinase in the case group and the control group were 0.43 ± 0.20, 4.30 ± 0.91, 10.85 ± 1.70 and 0.67 ± 0.32, 0.099 ± 0.028, 0.20 ± 0.071, respectively (p < .05). The down-regulated expression of CPI-17 phosphorylated proteins might be one of the important factors of UAI-PPH, while the activity reduction of PKC and Rho kinase might be the reason that led to the phosphorylation level reduction of USM-CPI-17 in UAI-PPH. Impact Statement What is already known on this subject? The studies have shown that in the late pregnancy period, the total protein and phosphorylated protein of myometrial CPI-17 are significantly higher than in the non-pregnancy state, and they were all involved in regulating and enhancing the Ca2+ sensitivity of USMC during the pregnancy. The data regarding the CPI-17-signal pathway-mediated Ca2+ sensitivity in UAI-PPH is sparse. What do the results of this study add? We have shown that the down-regulated expression of CPI-17 phosphorylated proteins might be one of the important factors of UAI-PPH, while the activity reduction of PKC and Rho kinase might be the reason that led to the phosphorylation level reduction of USM-CPI-17 in UAI-PPH. What are the implications of these findings for clinical practice and/or further research? Further studies are needed to confirm the pathogenesis of CPI-17-signal pathway-mediated Ca2+ sensitivity in UAI-PPH.
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Affiliation(s)
- Qiuping Liao
- a Department of Gynaecology and Obstetrics, Fujian Provincial Maternity and Children's Hospital , Affiliated Hospital of Fujian Medical University , Fuzhou , PR China
| | - Jianying Yan
- a Department of Gynaecology and Obstetrics, Fujian Provincial Maternity and Children's Hospital , Affiliated Hospital of Fujian Medical University , Fuzhou , PR China
| | - Zhimei Zhou
- b Second Affiliated Hospital of Fujian Medical University , Quanzhou , PR China
| | - Jinying Luo
- a Department of Gynaecology and Obstetrics, Fujian Provincial Maternity and Children's Hospital , Affiliated Hospital of Fujian Medical University , Fuzhou , PR China
| | - Qing Han
- a Department of Gynaecology and Obstetrics, Fujian Provincial Maternity and Children's Hospital , Affiliated Hospital of Fujian Medical University , Fuzhou , PR China
| | - Qinjian Zhang
- a Department of Gynaecology and Obstetrics, Fujian Provincial Maternity and Children's Hospital , Affiliated Hospital of Fujian Medical University , Fuzhou , PR China
| | - Rongxin Chen
- a Department of Gynaecology and Obstetrics, Fujian Provincial Maternity and Children's Hospital , Affiliated Hospital of Fujian Medical University , Fuzhou , PR China
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11
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Maguire LH, Handelman SK, Du X, Chen Y, Pers TH, Speliotes EK. Genome-wide association analyses identify 39 new susceptibility loci for diverticular disease. Nat Genet 2018; 50:1359-1365. [PMID: 30177863 PMCID: PMC6168378 DOI: 10.1038/s41588-018-0203-z] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 07/23/2018] [Indexed: 12/31/2022]
Abstract
Diverticular disease is common and has a high morbidity. Treatments are limited owing to the poor understanding of its pathophysiology. Here, to elucidate its etiology, we performed a genome-wide association study of diverticular disease (27,444 cases; 382,284 controls) from the UK Biobank and tested for replication in the Michigan Genomics Initiative (2,572 cases; 28,649 controls). We identified 42 loci associated with diverticular disease; 39 of these loci are novel. Using data-driven expression-prioritized integration for complex traits (DEPICT), we show that genes in these associated regions are significantly enriched for expression in mesenchymal stem cells and multiple connective tissue cell types and are co-expressed with genes that have a role in vascular and mesenchymal biology. Genes in these associated loci have roles in immunity, extracellular matrix biology, cell adhesion, membrane transport and intestinal motility. Phenome-wide association analysis of the 42 variants shows a common etiology of diverticular disease with obesity and hernia. These analyses shed light on the genomic landscape of diverticular disease.
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Affiliation(s)
- Lillias H Maguire
- Department of Surgery, Division of Colorectal Surgery, University of Michigan, Ann Arbor, MI, USA.
| | - Samuel K Handelman
- Department of Internal Medicine, Division of Gastroenterology, Ann Arbor, MI, USA
| | - Xiaomeng Du
- Department of Internal Medicine, Division of Gastroenterology, Ann Arbor, MI, USA
| | - Yanhua Chen
- Department of Internal Medicine, Division of Gastroenterology, Ann Arbor, MI, USA
| | - Tune H Pers
- The Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark
| | - Elizabeth K Speliotes
- Department of Internal Medicine, Division of Gastroenterology, Ann Arbor, MI, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
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12
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Sung TS, Hwang SJ, Koh SD, Bayguinov Y, Peri LE, Blair PJ, Webb TI, Pardo DM, Rock JR, Sanders KM, Ward SM. The cells and conductance mediating cholinergic neurotransmission in the murine proximal stomach. J Physiol 2018; 596:1549-1574. [PMID: 29430647 PMCID: PMC5924836 DOI: 10.1113/jp275478] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 01/26/2018] [Indexed: 12/23/2022] Open
Abstract
KEY POINTS Enteric neurotransmission is essential for gastrointestinal (GI) motility, although the cells and conductances responsible for post-junctional responses are controversial. The calcium-activated chloride conductance (CaCC), anoctamin-1 (Ano1), was expressed by intramuscular interstitial cells of Cajal (ICC-IM) in proximal stomach and not resolved in smooth muscle cells (SMCs). Cholinergic nerve fibres were closely apposed to ICC-IM. Conductances activated by cholinergic stimulation in isolated ICC-IM and SMCs were determined. A CaCC was activated by carbachol in ICC-IM and a non-selective cation conductance in SMCs. Responses to cholinergic nerve stimulation were studied. Excitatory junction potentials (EJPs) and mechanical responses were evoked in wild-type mice but absent or greatly reduced with knockout/down of Ano1. Drugs that block Ano1 inhibited the conductance activated by carbachol in ICC-IM and EJPs and mechanical responses in tissues. The data of the present study suggest that electrical and mechanical responses to cholinergic nerve stimulation are mediated by Ano1 expressed in ICC-IM and not SMCs. ABSTRACT Enteric motor neurotransmission is essential for normal gastrointestinal (GI) motility. Controversy exists regarding the cells and ionic conductance(s) that mediate post-junctional neuroeffector responses to motor neurotransmitters. Isolated intramuscular ICC (ICC-IM) and smooth muscle cells (SMCs) from murine fundus muscles were used to determine the conductances activated by carbachol (CCh) in each cell type. The calcium-activated chloride conductance (CaCC), anoctamin-1 (Ano1) is expressed by ICC-IM but not resolved in SMCs, and CCh activated a Cl- conductance in ICC-IM and a non-selective cation conductance in SMCs. We also studied responses to nerve stimulation using electrical-field stimulation (EFS) of intact fundus muscles from wild-type and Ano1 knockout mice. EFS activated excitatory junction potentials (EJPs) in wild-type mice, although EJPs were absent in mice with congenital deactivation of Ano1 and greatly reduced in animals in which the CaCC-Ano1 was knocked down using Cre/loxP technology. Contractions to cholinergic nerve stimulation were also greatly reduced in Ano1 knockouts. SMCs cells also have receptors and ion channels activated by muscarinic agonists. Blocking acetylcholine esterase with neostigmine revealed a slow depolarization that developed after EJPs in wild-type mice. This depolarization was still apparent in mice with genetic deactivation of Ano1. Pharmacological blockers of Ano1 also inhibited EJPs and contractile responses to muscarinic stimulation in fundus muscles. The data of the present study are consistent with the hypothesis that ACh released from motor nerves binds muscarinic receptors on ICC-IM with preference and activates Ano1. If metabolism of acetylcholine is inhibited, ACh overflows and binds to extrajunctional receptors on SMCs, eliciting a slower depolarization response.
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Affiliation(s)
- Tae Sik Sung
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Sung Jin Hwang
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Yulia Bayguinov
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Lauen E. Peri
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Peter J. Blair
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Timothy I. Webb
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - David M. Pardo
- Department of AnatomyUniversity of CaliforniaSan FranciscoCAUSA
| | - Jason R. Rock
- Center for Regenerative MedicineBoston University School of MedicineBostonMAUSA
| | - Kenton M. Sanders
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Sean M. Ward
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
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13
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Wang F, Sun Y. Overexpression of Myosin Phosphatase Target Subunit 1 (MYPT1) Inhibits Tumor Progression and Metastasis of Gastric Cancer. Med Sci Monit 2018; 24:2508-2517. [PMID: 29687789 PMCID: PMC5937360 DOI: 10.12659/msm.906852] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Background Myosin phosphatase target subunit 1 (MYPT1) serves as a subgroup of myosin phosphatases, and is frequently low-expressed in human cancers. However, little is known about the effects of MYPT1 in gastric cancer (GC). Material/Methods In our study, MYPT1 expression was detected by quantitative real-time reverse transcription PCR (qRT-PCR) in GC tissues, different advanced pathological stages of GC tissues, and preoperative and postoperative patients. Kaplan-Meier analysis was used to measure the overall survival of GC patients. MYPT1 expression was analyzed by qRT-PCR and Western blot assays in GES-1 cells and GC cells. Cell proliferation, cycle, and migration and invasion abilities were detected by CCK-8, flow cytometry, and Transwell assays. E-cadherin, TIMP-2, MMP-2, MMP-9 RhoA, and p-RhoA expressions were assessed by qRT-PCR and Western blot assays in treated SNU-5 cells. Results Our results indicated that MYPT1 was down-regulated in GC tissues and cells, and is related to clinical stages and overall survival of GC. Functional research demonstrated that overexpression of MYPT1 can inhibit cell proliferation, cell cycle progression, and migration and invasion of GC cells. Many studies on mechanisms reported that overexpression of MYPT1 dramatically improved the expression levels of cell cycle-related genes (Cyclin D1 and c-myc), significantly increased epithelial marker (E-cadherin) expression, and decreased invasion-associated genes (TIMP-2 and MMP-2) expressions in SNU-5 cells. In addition, we found that MYPT1 suppressed RhoA phosphorylation. Conclusions We verified that MYPT1 inhibits GC cell proliferation and metastasis by regulating RhoA phosphorylation.
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Affiliation(s)
- Fengyong Wang
- Department of Gastrointestinal and Pancreatic Surgery, Tongde Hospital of Zhejiang Province, Hangzhou, Zhejiang, China (mainland)
| | - Yuanshui Sun
- Department of Gastrointestinal and Pancreatic Surgery, Tongde Hospital of Zhejiang Province, Hangzhou, Zhejiang, China (mainland)
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14
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Yang Q, Fujii W, Kaji N, Kakuta S, Kada K, Kuwahara M, Tsubone H, Ozaki H, Hori M. The essential role of phospho‐T38 CPI‐17 in the maintenance of physiological blood pressure using genetically modified mice. FASEB J 2018; 32:2095-2109. [DOI: 10.1096/fj.201700794r] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Affiliation(s)
- Qunhui Yang
- Department of Veterinary Pharmacology, Laboratory of Applied Genetics, Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Wataru Fujii
- Laboratory of Applied Genetics, Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Noriyuki Kaji
- Department of Veterinary Pharmacology, Laboratory of Applied Genetics, Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Shigeru Kakuta
- Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Kodai Kada
- Department of Veterinary Pharmacology, Laboratory of Applied Genetics, Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Masayoshi Kuwahara
- Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Hirokazu Tsubone
- Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Hiroshi Ozaki
- Department of Veterinary Pharmacology, Laboratory of Applied Genetics, Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Masatoshi Hori
- Department of Veterinary Pharmacology, Laboratory of Applied Genetics, Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
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15
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Yin Y, Li Y, Pan J, Tang R, Zhu J, Qin Z, Xu X, Wang J. Expression of MYPT1, CPI-17 and MLC20 in ileum of neonatal mouse NEC model and its significance. Exp Ther Med 2017; 14:2221-2227. [PMID: 28962146 PMCID: PMC5609160 DOI: 10.3892/etm.2017.4783] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 07/04/2017] [Indexed: 11/06/2022] Open
Abstract
The present study determined the changes in the expression levels of MYPT1, CPI-17 and MLC20 in the ileum of mice with neonatal induced necrotizing enterocolitis (NEC) to provide a basis for a pathogenesis model that includes smooth muscle changes during NEC. A group of 7-day-old BALB/c mice were fed with formula (40 µl/g, 5 times/day) and given hypoxia treatments (5% O2 and 95% N2 for 10 min, twice daily) for 4 days to induce NEC and establish a mouse model. A control group of 7-day-old BALB/c mice were left with their mother for the duration of the treatment. After establishing the model, the two groups of mice were sacrificed, and the terminal ileum tissue was collected and subjected to western blot analysis and immunohistochemistry. The results showed the expression levels of MYPT1 and pMYPT1 in the ileum of the mice in the NEC group were lower than those in the control group (P<0.01). The levels of CPI17 and pCPI17 were higher in the NEC group compared with those in the control group. The expression level of MLC20 in NEC group was lower than that in the control group (P<0.01), but the level of pMLC20 in the NEC group was higher (P<0.05). The results of immunohistochemistry showed that the staining intensities of MYPT1, CPI-17 and MLC20 in the NEC group were lighter than those in the control group, and the proportion of positive cells was also lower in the NEC group (P<0.01). Taken together our results suggest that establishment of NEC is accompanied by changes in the protein levels of MYPT1 and pCPI-17, which can regulate smooth muscle contraction in the ileum.
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Affiliation(s)
- Yinyu Yin
- Department of General Surgery, Xuzhou Children's Hospital, Xuzhou, Jiangsu 221006, P.R. China
| | - Yiping Li
- Department of General Surgery, Children's Hospital of Soochow University, Suzhou, Jiangsu 215025, P.R. China
| | - Jian Pan
- Department of General Surgery, Children's Hospital of Soochow University, Suzhou, Jiangsu 215025, P.R. China
| | - Ruze Tang
- Department of General Surgery, Children's Hospital of Soochow University, Suzhou, Jiangsu 215025, P.R. China
| | - Jie Zhu
- Department of General Surgery, Children's Hospital of Soochow University, Suzhou, Jiangsu 215025, P.R. China
| | - Zhenfang Qin
- Department of General Surgery, Xuzhou Children's Hospital, Xuzhou, Jiangsu 221006, P.R. China
| | - Xiaobing Xu
- Department of General Surgery, Xuzhou Children's Hospital, Xuzhou, Jiangsu 221006, P.R. China
| | - Jian Wang
- Department of General Surgery, Children's Hospital of Soochow University, Suzhou, Jiangsu 215025, P.R. China
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16
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Liu B, Lee YC, Alwaal A, Wang G, Banie L, Lin CS, Lin G, Lue TF. Carbachol-induced signaling through Thr696-phosphorylation of myosin phosphatase-targeting subunit 1 (MYPT1) in rat bladder smooth muscle cells. Int Urol Nephrol 2016; 48:1237-1242. [PMID: 27118568 DOI: 10.1007/s11255-016-1303-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 04/19/2016] [Indexed: 12/18/2022]
Abstract
PURPOSE Lines of evidence suggest that Rho-associated protein kinase (ROCK)-mediated myosin phosphatase-targeting subunit 1 (MYPT1) phosphorylation plays a central role in smooth muscle contraction. However, the physiological significance of MYPT1 phosphorylation at Thr696 catalyzed by ROCK in bladder smooth muscle remains controversial. We attempt to directly observe the quantitative protein expression of Rho A/ROCK and phosphorylation of MYPT1 at Thr696 after carbachol administration in rat bladder smooth muscle cells (RBMSCs). MATERIALS AND METHODS Primary cultured smooth muscle cells were obtained from rat bladders. The effects of both concentration and time-course induced by the muscarinic agonist carbachol were investigated by assessing the expression of Rho A/ROCK and MYPT1 phosphorylation at Thr696 using Western blot. RESULTS In the dose-course studies, carbachol showed significant increase in phosphorylation of MYPT1 at Thr696 (p-MYPT1) from concentrations of 15-100 μM based on Western blot results (p < 0.05, ANOVA test). In the time-course studies, treatment of cells with 15 μM of carbachol significantly enhanced the expression of p-MYPT1 from 3 to 15 h (p < 0.05, ANOVA test) and induced the expression of Rho A from 10 to 120 min (p < 0.05, ANOVA test). CONCLUSIONS Carbachol can induce the expression of ROCK pathway, leading to MYPT1 phosphorylation at Thr696 and thereby sustained RBSMCs contraction.
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Affiliation(s)
- Benchun Liu
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
| | - Yung-Chin Lee
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
- Department of Urology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Amjad Alwaal
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
| | - Guifang Wang
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
| | - Lia Banie
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
| | - Ching-Shwun Lin
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
| | - Guiting Lin
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
| | - Tom F Lue
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA.
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17
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Perrino BA. Calcium Sensitization Mechanisms in Gastrointestinal Smooth Muscles. J Neurogastroenterol Motil 2016; 22:213-25. [PMID: 26701920 PMCID: PMC4819859 DOI: 10.5056/jnm15186] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Accepted: 12/22/2014] [Indexed: 01/05/2023] Open
Abstract
An increase in intracellular Ca2+ is the primary trigger of contraction of gastrointestinal (GI) smooth muscles. However, increasing the Ca2+ sensitivity of the myofilaments by elevating myosin light chain phosphorylation also plays an essential role. Inhibiting myosin light chain phosphatase activity with protein kinase C-potentiated phosphatase inhibitor protein-17 kDa (CPI-17) and myosin phosphatase targeting subunit 1 (MYPT1) phosphorylation is considered to be the primary mechanism underlying myofilament Ca2+ sensitization. The relative importance of Ca2+ sensitization mechanisms to the diverse patterns of GI motility is likely related to the varied functional roles of GI smooth muscles. Increases in CPI-17 and MYPT1 phosphorylation in response to agonist stimulation regulate myosin light chain phosphatase activity in phasic, tonic, and sphincteric GI smooth muscles. Recent evidence suggests that MYPT1 phosphorylation may also contribute to force generation by reorganization of the actin cytoskeleton. The mechanisms responsible for maintaining constitutive CPI-17 and MYPT1 phosphorylation in GI smooth muscles are still largely unknown. The characteristics of the cell-types comprising the neuroeffector junction lead to fundamental differences between the effects of exogenous agonists and endogenous neurotransmitters on Ca2+ sensitization mechanisms. The contribution of various cell-types within the tunica muscularis to the motor responses of GI organs to neurotransmission must be considered when determining the mechanisms by which Ca2+ sensitization pathways are activated. The signaling pathways regulating Ca2+ sensitization may provide novel therapeutic strategies for controlling GI motility. This article will provide an overview of the current understanding of the biochemical basis for the regulation of Ca2+ sensitization, while also discussing the functional importance to different smooth muscles of the GI tract.
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Affiliation(s)
- Brian A Perrino
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
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18
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Gao N, Chang AN, He W, Chen CP, Qiao YN, Zhu M, Kamm KE, Stull JT. Physiological signalling to myosin phosphatase targeting subunit-1 phosphorylation in ileal smooth muscle. J Physiol 2016; 594:3209-25. [PMID: 26847850 DOI: 10.1113/jp271703] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/21/2016] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS The extent of myosin regulatory light chain phosphorylation (RLC) necessary for smooth muscle contraction depends on the respective activities of Ca(2+) /calmodulin-dependent myosin light chain kinase and myosin light chain phosphatase (MLCP), which contains a regulatory subunit MYPT1 bound to the phosphatase catalytic subunit and myosin. MYPT1 showed significant constitutive T696 and T853 phosphorylation, which is predicted to inhibit MLCP activity in isolated ileal smooth muscle tissues, with additional phosphorylation upon pharmacological treatment with the muscarinic agonist carbachol. Electrical field stimulation (EFS), which releases ACh from nerves, increased force and RLC phosphorylation but not MYPT1 T696 or T853 phosphorylation. The conditional knockout of MYPT1 or the knockin mutation T853A in mice had no effect on the frequency-maximal force responses to EFS in isolated ileal tissues. Physiological RLC phosphorylation and force development in ileal smooth muscle depend on myosin light chain kinase and MLCP activities without changes in constitutive MYPT1 phosphorylation. ABSTRACT Smooth muscle contraction initiated by myosin regulatory light chain (RLC) phosphorylation is dependent on the relative activities of Ca(2+) /calmodulin-dependent myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP). We have investigated the physiological role of the MLCP regulatory subunit MYPT1 in ileal smooth muscle in adult mice with (1) smooth muscle-specific deletion of MYPT1; (2) non-phosphorylatable MYPT1 containing a T853A knockin mutation; and (3) measurements of force and protein phosphorylation responses to cholinergic neurostimulation initiated by electric field stimulation. Isolated MYPT1-deficient tissues from MYPT1(SM-/-) mice contracted and relaxed rapidly with moderate differences in sustained responses to KCl and carbachol treatments and washouts, respectively. Similarly, measurements of regulatory proteins responsible for RLC phosphorylation during contractions also revealed moderate changes. There were no differences in contractile or RLC phosphorylation responses to carbachol between tissues from normal mice vs. MYPT1 T853A knockin mice. Quantitatively, there was substantial MYPT1 T696 and T853 phosphorylation in wild-type tissues under resting conditions, predicting a high extent of MLCP phosphatase inhibition. Reduced PP1cδ activity in MYPT1-deficient tissues may be similar to attenuated MLCP activity in wild-type tissues resulting from constitutively phosphorylated MYPT1. Electric field stimulation increased RLC phosphorylation and force development in tissues from wild-type mice without an increase in MYPT1 phosphorylation. Thus, physiological RLC phosphorylation and force development in ileal smooth muscle appear to be dependent on MLCK and MLCP activities without changes in constitutive MYPT1 phosphorylation.
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Affiliation(s)
- Ning Gao
- Department of Physiology, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - Audrey N Chang
- Department of Physiology, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - Weiqi He
- Model Animal Research Centre and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China.,Current address: Cambridge-Suda (CAM-SU) Genomic Resource Centre, Soochow University, Suzhou, China
| | - Cai-Ping Chen
- Model Animal Research Centre and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Yan-Ning Qiao
- Model Animal Research Centre and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Minsheng Zhu
- Model Animal Research Centre and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Kristine E Kamm
- Department of Physiology, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - James T Stull
- Department of Physiology, University of Texas Southwestern Medical Centre, Dallas, TX, USA
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19
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Anderson CD, Kendig DM, Al-Qudah M, Mahavadi S, Murthy KS, Grider JR. Role of various kinases in muscarinic M3 receptor-mediated contraction of longitudinal muscle of rat colon. J Smooth Muscle Res 2015; 50:103-19. [PMID: 25891767 PMCID: PMC4862207 DOI: 10.1540/jsmr.50.103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The longitudinal muscle layer in gut is the functional opponent to the circular muscle
layer during peristalsis. Differences in innervation of the layers allow for the
contraction of one layer concurrently with the relaxation of the other, enabling the
passage of gut contents in a controlled fashion. Differences in development have given the
cells of the two layers differences in receptor populations, membrane lipid handling, and
calcium handling profiles/behaviors. The contractile activity of the longitudinal muscle
is largely mediated by cholinergic neural input from myenteric plexus. Activation of
muscarinic receptors leads to rapid activation of several kinases including MLC kinase,
ERK1/2, CaMKII and Rho kinase. Phosphorylation of myosin light chain (MLC20) by
MLC kinase (MLCK) is a prerequisite for contraction in both circular and longitudinal
muscle cells. In rat colonic longitudinal muscle strips, we measured muscarinic
receptor-mediated contraction following incubation with kinase inhibitors. Basal tension
was differentially regulated by Rho kinase, ERK1/2, CaMKII and CaMKK. Selective inhibitors
of Rho kinase, ERK1/2, CaMKK/AMPK, and CaMKII each reduced carbachol-induced contraction
in the innervated muscle strips. These inhibitors had no direct effect on MLCK activity.
Thus unlike previously reported for isolated muscle cells where CaMKII and ERK1/2 are not
involved in contraction, we conclude that the regulation of carbachol-induced contraction
in innervated longitudinal muscle strips involves the interplay of Rho kinase, ERK1/2,
CaMKK/AMPK, and CAMKII.
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Affiliation(s)
- Charles D Anderson
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, USA
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20
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Chen CP, Chen X, Qiao YN, Wang P, He WQ, Zhang CH, Zhao W, Gao YQ, Chen C, Tao T, Sun J, Wang Y, Gao N, Kamm KE, Stull JT, Zhu MS. In vivo roles for myosin phosphatase targeting subunit-1 phosphorylation sites T694 and T852 in bladder smooth muscle contraction. J Physiol 2014; 593:681-700. [PMID: 25433069 DOI: 10.1113/jphysiol.2014.283853] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 11/18/2014] [Indexed: 01/12/2023] Open
Abstract
KEY POINTS Force production and maintenance in smooth muscle is largely controlled by myosin regulatory light chain (RLC) phosphorylation, which relies on a balance between Ca(2+)/calmodulin-dependent myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP) activities. MYPT1 is the regulatory subunit of MLCP that biochemically inhibits MLCP activity via T694 or T852 phosphorylation in vitro. Here we separately investigated the contribution of these two phosphorylation sites in bladder smooth muscles by establishing two single point mutation mouse lines, T694A and T852A, and found that phosphorylation of MYPT1 T694, but not T852, mediates force maintenance via inhibition of MLCP activity and enhancement of RLC phosphorylation in vivo. Our findings reveal the role of MYPT1 T694/T852 phosphorylation in vivo in regulation of smooth muscle contraction. ABSTRACT Force production and maintenance in smooth muscle is largely controlled by different signalling modules that fine tune myosin regulatory light chain (RLC) phosphorylation, which relies on a balance between Ca(2+)/calmodulin-dependent myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP) activities. To investigate the regulation of MLCP activity in vivo, we analysed the role of two phosphorylation sites on MYPT1 (regulatory subunit of MLCP) that biochemically inhibit MLCP activity in vitro. MYPT1 is constitutively phosphorylated at T694 by unidentified kinases in vivo, whereas the T852 site is phosphorylated by RhoA-associated protein kinase (ROCK). We established two mouse lines with alanine substitution of T694 or T852. Isolated bladder smooth muscle from T852A mice displayed no significant changes in RLC phosphorylation or force responses, but force was inhibited with a ROCK inhibitor. In contrast, smooth muscles containing the T694A mutation showed a significant reduction of force along with reduced RLC phosphorylation. The contractile responses of T694A mutant smooth muscle were also independent of ROCK activation. Thus, phosphorylation of MYPT1 T694, but not T852, is a primary mechanism contributing to inhibition of MLCP activity and enhancement of RLC phosphorylation in vivo. The constitutive phosphorylation of MYPT1 T694 may provide a mechanism for regulating force maintenance of smooth muscle.
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Affiliation(s)
- Cai-Ping Chen
- Model Animal Research Center and MOE Key Laboratory of Animal Models of Disease, Nanjing University, Nanjing, China
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21
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Mori D, Watanabe N, Kaminuma O, Murata T, Hiroi T, Ozaki H, Hori M. IL-17A induces hypo-contraction of intestinal smooth muscle via induction of iNOS in muscularis macrophages. J Pharmacol Sci 2014; 125:394-405. [PMID: 25069526 DOI: 10.1254/jphs.14060fp] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Intestinal inflammation causes disorder in bowel motility. Th17 cytokines are involved in intestinal inflammation. To understand the role of interleukin (IL)-17 in intestinal motility, we examined effects of IL-17A on contractile activities of organ-cultured ileum. Rat ileal smooth muscle strips were organ cultured with IL-17A. Muscle contraction was measured, and cells expressing inducible nitric oxide synthase (iNOS) were identified with immunohistochemistry. Creating Th17-transferred colitis model mice, in vivo effects of IL-17 on contractile activities, and iNOS mRNA expression in colonic smooth muscle were investigated. Treatment with IL-17A for 12 h and 3 days attenuated carbachol- and membrane depolarization-induced contractions in organ-cultured rat ileum. N(G)-Nitro-l-arginine methyl ester (100 μM), a nitric oxide synthase inhibitor, completely reversed the IL-17A-induced inhibition of contractile force. Ileal tissue cultured in the presence of IL-17A showed increased expression of iNOS mRNA and protein. Immunohistochemical analysis using an iNOS antibody revealed that iNOS protein was expressed on ED2-positive muscularis macrophages. The level of iNOS mRNA was also increased in inflamed colonic smooth muscle of Th17-transferred colitis model mice. In intestinal inflammation, IL-17A induces an intestinal motility disorder through iNOS expression in muscularis macrophages.
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Affiliation(s)
- Daisuke Mori
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Japan
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22
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Rho kinase acts as a downstream molecule to participate in protein kinase Cε regulation of vascular reactivity after hemorrhagic shock in rats. Shock 2014; 42:239-45. [PMID: 24827390 DOI: 10.1097/shk.0000000000000199] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Our previous study demonstrated that Rho kinase and protein kinase C (PKC) played important parts in the regulation of vascular reactivity after shock. Using superior mesenteric arteries (SMAs) from hemorrhagic shock rats and hypoxia-treated vascular smooth muscle cells (VSMCs), relationship of PKCε regulation of vascular reactivity to Rho kinase, as well as the signal transduction after shock, was investigated. The results showed that inhibition of Rho kinase with the Rho kinase-specific inhibitor Y-27632 antagonized the PKCε-specific agonist carbachol and highly expressed PKCε-induced increase of vascular reactivity in SMAs and VSMCs, whereas inhibition of PKCε with its specific inhibitory peptide did not antagonize the Rho kinase agonist (U-46619)-induced increase of vascular reactivity in SMAs and VSMCs. Activation of PKCε or highly expressed PKCε upregulated the activity of Rho kinase and the phosphorylation of PKC-dependent phosphatase inhibitor 17 (CPI-17), zipper interacting protein kinase (ZIPK), and integrin-linked kinase (ILK), whereas activation of Rho kinase increased only CPI-17 phosphorylation. The specific neutralization antibodies of ZIPK and ILK antagonized PKCε-induced increases in the activity of Rho kinase, but CPI-17 neutralization antibody did not antagonize this effect. These results suggested that Rho kinase takes part in the regulation of PKCε on vascular reactivity after shock. Rho kinase is downstream of PKCε. Protein kinase Cε activates Rho kinase via ZIPK and ILK; CPI-17 is downstream of Rho kinase.
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23
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Tsai MH, Chang AN, Huang J, He W, Sweeney HL, Zhu M, Kamm KE, Stull JT. Constitutive phosphorylation of myosin phosphatase targeting subunit-1 in smooth muscle. J Physiol 2014; 592:3031-51. [PMID: 24835173 DOI: 10.1113/jphysiol.2014.273011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Smooth muscle contraction initiated by myosin regulatory light chain (RLC) phosphorylation is dependent on the relative activities of Ca(2+)-calmodulin-dependent myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP). We have investigated the physiological role of the MLCP regulatory subunit MYPT1 in bladder smooth muscle containing a smooth muscle-specific deletion of MYPT1 in adult mice. Deep-sequencing analyses of mRNA and immunoblotting revealed that MYPT1 depletion reduced the amount of PP1cδ with no compensatory changes in expression of other MYPT1 family members. Phosphatase activity towards phosphorylated smooth muscle heavy meromyosin was proportional to the amount of PP1cδ in total homogenates from wild-type or MYPT1-deficient tissues. Isolated MYPT1-deficient tissues from MYPT1(SM-/-) mice contracted with moderate differences in response to KCl and carbachol treatments, and relaxed rapidly with comparable rates after carbachol removal and only 1.5-fold slower after KCl removal. Measurements of phosphorylated proteins in the RLC signalling and actin polymerization modules during contractions revealed moderate changes. Using a novel procedure to quantify total phosphorylation of MYPT1 at Thr696 and Thr853, we found substantial phosphorylation in wild-type tissues under resting conditions, predicting attenuation of MLCP activity. Reduced PP1cδ activity in MYPT1-deficient tissues may be similar to the attenuated MLCP activity in wild-type tissues resulting from constitutively phosphorylated MYPT1. Constitutive phosphorylation of MYPT1 Thr696 and Thr853 may thus represent a physiological mechanism acting in concert with agonist-induced MYPT1 phosphorylation to inhibit MLCP activity. In summary, MYPT1 deficiency may not cause significant derangement of smooth muscle contractility because the effective MLCP activity is not changed.
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Affiliation(s)
- Ming-Ho Tsai
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Audrey N Chang
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Jian Huang
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Weiqi He
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - H Lee Sweeney
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Minsheng Zhu
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Kristine E Kamm
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - James T Stull
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
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24
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Townsend EA, Zhang Y, Xu C, Wakita R, Emala CW. Active components of ginger potentiate β-agonist-induced relaxation of airway smooth muscle by modulating cytoskeletal regulatory proteins. Am J Respir Cell Mol Biol 2014; 50:115-24. [PMID: 23962082 PMCID: PMC3930933 DOI: 10.1165/rcmb.2013-0133oc] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 07/08/2013] [Indexed: 11/24/2022] Open
Abstract
β-Agonists are the first-line therapy to alleviate asthma symptoms by acutely relaxing the airway. Purified components of ginger relax airway smooth muscle (ASM), but the mechanisms are unclear. By elucidating these mechanisms, we can explore the use of phytotherapeutics in combination with traditional asthma therapies. The objectives of this study were to: (1) determine if 6-gingerol, 8-gingerol, or 6-shogaol potentiate β-agonist-induced ASM relaxation; and (2) define the mechanism(s) of action responsible for this potentiation. Human ASM was contracted in organ baths. Tissues were relaxed dose dependently with β-agonist, isoproterenol, in the presence of vehicle, 6-gingerol, 8-gingerol, or 6-shogaol (100 μM). Primary human ASM cells were used for cellular experiments. Purified phosphodiesterase (PDE) 4D or phospholipase C β enzyme was used to assess inhibitory activity of ginger components using fluorescent assays. A G-LISA assay was used to determine the effects of ginger constituents on Ras homolog gene family member A activation. Significant potentiation of isoproterenol-induced relaxation was observed with each of the ginger constituents. 6-Shogaol showed the largest shift in isoproterenol half-maximal effective concentration. 6-Gingerol, 8-gingerol, or 6-shogaol significantly inhibited PDE4D, whereas 8-gingerol and 6-shogaol also inhibited phospholipase C β activity. 6-Shogaol alone inhibited Ras homolog gene family member A activation. In human ASM cells, these constituents decreased phosphorylation of 17-kD protein kinase C-potentiated inhibitory protein of type 1 protein phosphatase and 8-gingerol decreased myosin light chain phosphorylation. Isolated components of ginger potentiate β-agonist-induced relaxation in human ASM. This potentiation involves PDE4D inhibition and cytoskeletal regulatory proteins. Together with β-agonists, 6-gingerol, 8-gingerol, or 6-shogaol may augment existing asthma therapy, resulting in relief of symptoms through complementary intracellular pathways.
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Affiliation(s)
| | - Yi Zhang
- Department of Anesthesiology, Columbia University, New York, New York; and
| | - Carrie Xu
- Department of Anesthesiology, Columbia University, New York, New York; and
| | - Ryo Wakita
- Department of Anesthesiology, Columbia University, New York, New York; and
- Section of Anesthesiology and Clinical Physiology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Charles W. Emala
- Department of Anesthesiology, Columbia University, New York, New York; and
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25
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He W, Qiao Y, Peng Y, Zha J, Zhang C, Chen C, Chen C, Wang P, Yang X, Li C, Kamm KE, Stull JT, Zhu M. Altered contractile phenotypes of intestinal smooth muscle in mice deficient in myosin phosphatase target subunit 1. Gastroenterology 2013; 144:1456-65, 1465.e1-5. [PMID: 23499953 PMCID: PMC3782749 DOI: 10.1053/j.gastro.2013.02.045] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 01/31/2013] [Accepted: 02/05/2013] [Indexed: 01/02/2023]
Abstract
BACKGROUND & AIMS The regulatory subunit of myosin light chain phosphatase, MYPT1, has been proposed to control smooth muscle contractility by regulating phosphorylation of the Ca(2+)-dependent myosin regulatory light chain. We generated mice with a smooth muscle-specific deletion of MYPT1 to investigate its physiologic role in intestinal smooth muscle contraction. METHODS We used the Cre-loxP system to establish Mypt1-floxed mice, with the promoter region and exon 1 of Mypt1 flanked by 2 loxP sites. These mice were crossed with SMA-Cre transgenic mice to generate mice with smooth muscle-specific deletion of MYPT1 (Mypt1(SMKO) mice). The phenotype was assessed by histologic, biochemical, molecular, and physiologic analyses. RESULTS Young adult Mypt1(SMKO) mice had normal intestinal motility in vivo, with no histologic abnormalities. On stimulation with KCl or acetylcholine, intestinal smooth muscles isolated from Mypt1(SMKO) mice produced robust and increased sustained force due to increased phosphorylation of the myosin regulatory light chain compared with muscle from control mice. Additional analyses of contractile properties showed reduced rates of force development and relaxation, and decreased shortening velocity, compared with muscle from control mice. Permeable smooth muscle fibers from Mypt1(SMKO) mice had increased sensitivity and contraction in response to Ca(2+). CONCLUSIONS MYPT1 is not essential for smooth muscle function in mice but regulates the Ca(2+) sensitivity of force development and contributes to intestinal phasic contractile phenotype. Altered contractile responses in isolated tissues could be compensated by adaptive physiologic responses in vivo, where gut motility is affected by lower intensities of smooth muscle stimulation for myosin phosphorylation and force development.
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Affiliation(s)
- Wei–Qi He
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Yan–Ning Qiao
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Ya–Jing Peng
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Juan–Min Zha
- Department of Gerontology, The First Hospital Affiliated with Nanjing Medical University, Nanjing, China
| | - Cheng–Hai Zhang
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Chen Chen
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Cai–Ping Chen
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Pei Wang
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Xiao Yang
- State Key Laboratory of Proteomics, Genetic Laboratory of Development and Disease, Institute of Biotechnology, Beijing, China
| | - Chao–Jun Li
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China,School of Medicine, Nanjing University, Nanjing, China
| | - Kristine E. Kamm
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - James T. Stull
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Min–Sheng Zhu
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China,Zhejiang Provincial Key Lab for Technology and Application of Model Organisms, School of Life Sciences, Wenzhou Medical College, Wenzhou, China
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26
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Bhetwal BP, Sanders KM, An C, Trappanese DM, Moreland RS, Perrino BA. Ca2+ sensitization pathways accessed by cholinergic neurotransmission in the murine gastric fundus. J Physiol 2013; 591:2971-86. [PMID: 23613531 DOI: 10.1113/jphysiol.2013.255745] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Ca(2+) sensitization of contraction has typically been investigated by bathing muscles in solutions containing agonists. However, it is unknown whether bath-applied agonists and enteric neurotransmission activate similar Ca(2+) sensitization mechanisms. We investigated protein kinase C (PKC)-potentiated phosphatase inhibitor protein of 17 kDa (CPI-17) and myosin phosphatase targeting subunit 1 (MYPT1) phosphorylation in murine gastric fundus muscles stimulated by bath-applied carbachol (CCh) or cholinergic motor neurotransmission. CCh increased MYPT1 phosphorylation at Thr696 (pT696) and Thr853 (pT853), CPI-17 at Thr38 (pT38), and myosin light chain at Ser19 (pS19). Electrical field stimulation (EFS) only increased pT38. In the presence of neostigmine, EFS increased pT38, pT853 and pS19. In fundus muscles of W/W(v) mice, EFS alone increased pT38 and pT853. Atropine blocked all contractions and all increases in pT696, pT853, pT38 and pS19. The Rho kinase (ROCK) inhibitor SAR1x blocked increases in pT853 and pT696. The PKC inhibitors Go6976 and Gf109203x or nicardipine blocked increases in pT38 and pT696. These findings suggest that cholinergic motor neurotransmission activates PKC-dependent CPI-17 phosphorylation. Bath-applied CCh recruits additional ROCK-dependent MYPT1 phosphorylation due to exposure of the agonist to a wider population of muscarinic receptors. Intramuscular interstitial cells of Cajal (ICC-IMs) and cholinesterases restrict ACh accessibility to a select population of muscarinic receptors, possibly only those expressed by ICC-IMs. These results provide the first biochemical evidence for focalized (or synaptic-like) neurotransmission, rather than diffuse 'volume' neurotransmission in a smooth muscle tissue. Furthermore, these findings demonstrate that bath application of contractile agonists to gastrointestinal smooth muscles does not mimic physiological responses to cholinergic neurotransmission.
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Affiliation(s)
- Bhupal P Bhetwal
- University of Nevada School of Medicine, Physiology and Cell Biology, University of Nevada, Reno, CMM203E, Reno, NV 89557, USA
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27
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Butler T, Paul J, Europe-Finner N, Smith R, Chan EC. Role of serine-threonine phosphoprotein phosphatases in smooth muscle contractility. Am J Physiol Cell Physiol 2013; 304:C485-504. [PMID: 23325405 DOI: 10.1152/ajpcell.00161.2012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The degree of phosphorylation of myosin light chain 20 (MLC20) is a major determinant of force generation in smooth muscle. Myosin phosphatases (MPs) contain protein phosphatase (PP) 1 as catalytic subunits and are the major enzymes that dephosphorylate MLC20. MP regulatory targeting subunit 1 (MYPT1), the main regulatory subunit of MP in all smooth muscles, is a key convergence point of contractile and relaxatory pathways. Combinations of regulatory mechanisms, including isoform splicing, multiple phosphorylation sites, and scaffolding proteins, modulate MYPT1 activity with tissue and agonist specificities to affect contraction and relaxation. Other members of the PP1 family that do not target myosin, as well as PP2A and PP2B, dephosphorylate a range of proteins that affect smooth muscle contraction. This review discusses the role of phosphatases in smooth muscle contractility with a focus on MYPT1 in uterine smooth muscle. Myometrium shares characteristics of vascular and other visceral smooth muscles yet, during healthy pregnancy, undergoes hypertrophy, hyperplasia, quiescence, and labor as physiological processes. Myometrium presents an accessible model for the study of normal and pathological smooth muscle function, and a better understanding of myometrial physiology may allow the development of novel therapeutics for the many disorders of myometrial physiology from preterm labor to dysmenorrhea.
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Affiliation(s)
- Trent Butler
- Mothers and Babies Research Centre, Faculty of Health, University of Newcastle, Callaghan, NSW 2308, Australia
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28
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Khromov AS, Momotani K, Jin L, Artamonov MV, Shannon J, Eto M, Somlyo AV. Molecular mechanism of telokin-mediated disinhibition of myosin light chain phosphatase and cAMP/cGMP-induced relaxation of gastrointestinal smooth muscle. J Biol Chem 2012; 287:20975-85. [PMID: 22544752 DOI: 10.1074/jbc.m112.341479] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phospho-telokin is a target of elevated cyclic nucleotide concentrations that lead to relaxation of gastrointestinal and some vascular smooth muscles (SM). Here, we demonstrate that in telokin-null SM, both Ca(2+)-activated contraction and Ca(2+) sensitization of force induced by a GST-MYPT1(654-880) fragment inhibiting myosin light chain phosphatase were antagonized by the addition of recombinant S13D telokin, without changing the inhibitory phosphorylation status of endogenous MYPT1 (the regulatory subunit of myosin light chain phosphatase) at Thr-696/Thr-853 or activity of Rho kinase. Cyclic nucleotide-induced relaxation of force in telokin-null ileum muscle was reduced but not correlated with a change in MYPT1 phosphorylation. The 40% inhibited activity of phosphorylated MYPT1 in telokin-null ileum homogenates was restored to nonphosphorylated MYPT1 levels by addition of S13D telokin. Using the GST-MYPT1 fragment as a ligand and SM homogenates from WT and telokin KO mice as a source of endogenous proteins, we found that only in the presence of endogenous telokin, thiophospho-GST-MYPT1 co-precipitated with phospho-20-kDa myosin regulatory light chain 20 and PP1. Surface plasmon resonance studies showed that S13D telokin bound to full-length phospho-MYPT1. Results of a protein ligation assay also supported interaction of endogenous phosphorylated MYPT1 with telokin in SM cells. We conclude that the mechanism of action of phospho-telokin is not through modulation of the MYPT1 phosphorylation status but rather it contributes to cyclic nucleotide-induced relaxation of SM by interacting with and activating the inhibited full-length phospho-MYPT1/PP1 through facilitating its binding to phosphomyosin and thus accelerating 20-kDa myosin regulatory light chain dephosphorylation.
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Affiliation(s)
- Alexander S Khromov
- Departments of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, USA
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