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Zhao W, Wang P, He W, Tao T, Li H, Li Y, Jiang W, Sun J, Ge X, Chen X, Zheng Y, Wei L, Chen C, Wang Y, Li C, Chen H, Yao B, Tang W, Zhu M. MYPT1 Down-regulation by Lipopolysaccharide-SIAH1/2 E3 Ligase-Ubiquitin-Proteasomal Degradation Contributes to Colonic Obstruction of Hirschsprung Disease. Cell Mol Gastroenterol Hepatol 2019; 9:345-347.e6. [PMID: 31759145 PMCID: PMC6997446 DOI: 10.1016/j.jcmgh.2019.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 11/10/2019] [Accepted: 11/12/2019] [Indexed: 12/13/2022]
Key Words
- anova, analysis of variance
- cir, circular
- d, dilated
- haec, hirschsprung-associated enterocolitis
- hd, hirschsprung disease
- long, longitudinal
- lps, lipopolysaccharide
- n, narrow
- rlc, regulatory light chain
- snp, sodium nitroprusside
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Affiliation(s)
- W Zhao
- State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Ministry of Education (MOE) Key Laboratory of Model Animal for Disease Study and the Medical School of Nanjing University, Nanjing, China; Reproductive Medical Center, Jinling Hospital Affiliated Medical School of Nanjing University, Nanjing, China
| | - P Wang
- State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Ministry of Education (MOE) Key Laboratory of Model Animal for Disease Study and the Medical School of Nanjing University, Nanjing, China
| | - W He
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Cambridge-Suda (CAM-SU) Genomic Resource Center, Soochow University, Suzhou, China
| | - T Tao
- State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Ministry of Education (MOE) Key Laboratory of Model Animal for Disease Study and the Medical School of Nanjing University, Nanjing, China
| | - H Li
- Department of Pediatric Surgery, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Y Li
- State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Ministry of Education (MOE) Key Laboratory of Model Animal for Disease Study and the Medical School of Nanjing University, Nanjing, China
| | - W Jiang
- Department of Pediatric Surgery, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - J Sun
- State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Ministry of Education (MOE) Key Laboratory of Model Animal for Disease Study and the Medical School of Nanjing University, Nanjing, China
| | - X Ge
- Department of General Surgery, Sir Run Run Shaw Hospital Affiliated Medical College of Zhejiang University, Hangzhou, China
| | - X Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Ministry of Education (MOE) Key Laboratory of Model Animal for Disease Study and the Medical School of Nanjing University, Nanjing, China
| | - Y Zheng
- State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Ministry of Education (MOE) Key Laboratory of Model Animal for Disease Study and the Medical School of Nanjing University, Nanjing, China
| | - L Wei
- State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Ministry of Education (MOE) Key Laboratory of Model Animal for Disease Study and the Medical School of Nanjing University, Nanjing, China
| | - C Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Ministry of Education (MOE) Key Laboratory of Model Animal for Disease Study and the Medical School of Nanjing University, Nanjing, China
| | - Y Wang
- State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Ministry of Education (MOE) Key Laboratory of Model Animal for Disease Study and the Medical School of Nanjing University, Nanjing, China
| | - C Li
- State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Ministry of Education (MOE) Key Laboratory of Model Animal for Disease Study and the Medical School of Nanjing University, Nanjing, China
| | - H Chen
- College of Life Science, Nanjing Normal University, Nanjing, China
| | - B Yao
- Reproductive Medical Center, Jinling Hospital Affiliated Medical School of Nanjing University, Nanjing, China.
| | - W Tang
- Department of Pediatric Surgery, Children's Hospital of Nanjing Medical University, Nanjing, China.
| | - M Zhu
- State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Ministry of Education (MOE) Key Laboratory of Model Animal for Disease Study and the Medical School of Nanjing University, Nanjing, China.
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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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Keef KD, Cobine CA. Control of Motility in the Internal Anal Sphincter. J Neurogastroenterol Motil 2019; 25:189-204. [PMID: 30827084 PMCID: PMC6474703 DOI: 10.5056/jnm18172] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 11/28/2018] [Accepted: 12/09/2018] [Indexed: 12/14/2022] Open
Abstract
The internal anal sphincter (IAS) plays an important role in the maintenance of fecal continence since it generates tone and is responsible for > 70% of resting anal pressure. During normal defecation the IAS relaxes. Historically, tone generation in gastrointestinal muscles was attributed to mechanisms arising directly from smooth muscle cells, ie, myogenic activity. However, slow waves are now known to play a fundamental role in regulating gastrointestinal motility and these electrical events are generated by the interstitial cells of Cajal. Recently, interstitial cells of Cajal, as well as slow waves, have also been identified in the IAS making them viable candidates for tone generation. In this review we discuss four different mechanisms that likely contribute to tone generation in the IAS. Three of these involve membrane potential, L-type Ca2+ channels and electromechanical coupling (ie, summation of asynchronous phasic activity, partial tetanus, and window current), whereas the fourth involves the regulation of myofilament Ca2+ sensitivity. Contractile activity in the IAS is also modulated by sympathetic motor neurons that significantly increase tone and anal pressure, as well as inhibitory motor neurons (particularly nitrergic and vasoactive intestinal peptidergic) that abolish contraction and assist with normal defecation. Alterations in IAS motility are associated with disorders such as fecal incontinence and anal fissures that significantly decrease the quality of life. Understanding in greater detail how tone is regulated in the IAS is important for developing more effective treatment strategies for these debilitating defecation disorders.
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Affiliation(s)
- Kathleen D Keef
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Caroline A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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Cobine CA, McKechnie M, Brookfield RJ, Hannigan KI, Keef KD. Comparison of inhibitory neuromuscular transmission in the Cynomolgus monkey IAS and rectum: special emphasis on differences in purinergic transmission. J Physiol 2018; 596:5319-5341. [PMID: 30198065 DOI: 10.1113/jp275437] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 09/07/2018] [Indexed: 01/04/2023] Open
Abstract
KEY POINTS Inhibitory neuromuscular transmission (NMT) was compared in the internal anal sphincter (IAS) and rectum of the Cynomolgus monkey, an animal with high gene sequence identity to humans. Nitrergic NMT was present in both muscles while purinergic NMT was limited to the rectum and VIPergic NMT to the IAS. The profile for monkey IAS more closely resembles humans than rodents. In both muscles, SK3 channels were localized to PDGFRα+ cells that were closely associated with nNOS+ /VIP+ nerves. Gene expression levels of P2RY subtypes were the same in IAS and rectum while KCNN expression levels were very similar. SK3 channel activation and inhibition caused faster/greater changes in contractile activity in rectum than IAS. P2Y1 receptor activation inhibited contraction in rectum while increasing contraction in IAS. The absence of purinergic NMT in the IAS may be due to poor coupling between P2Y1 receptors and SK3 channels on PDGFRα+ cells. ABSTRACT Inhibitory neuromuscular transmission (NMT) was compared in the internal anal sphincter (IAS) and rectum of the Cynomolgus monkey, an animal with a high gene sequence identity to humans. Electrical field stimulation produced nitric oxide synthase (NOS)-dependent contractile inhibition in both muscles whereas P2Y1-dependent purinergic NMT was restricted to rectum. An additional NOS-independent, α-chymotrypsin-sensitive component was identified in the IAS consistent with vasoactive intestinal peptide-ergic (VIPergic) NMT. Microelectrode recordings revealed slow NOS-dependent inhibitory junction potentials (IJPs) in both muscles and fast P2Y1-dependent IJPs in rectum. The basis for the difference in purinergic NMT was investigated. PDGFRα+ /SK3+ cells were closely aligned with nNOS+ /VIP+ neurons in both muscles. Gene expression of P2RY was the same in IAS and rectum (P2RY1>>P2RY2-14) while KCNN3 expression was 32% greater in rectum. The SK channel inhibitor apamin doubled contractile activity in rectum while having minimal effect in the IAS. Contractile inhibition elicited with the SK channel agonist CyPPA was five times faster in rectum than in the IAS. The P2Y1 receptor agonist MRS2365 inhibited contraction in rectum but increased contraction in the IAS. In conclusion, both the IAS and the rectum have nitrergic NMT whereas purinergic NMT is limited to rectum and VIPergic NMT to the IAS. The profile in monkey IAS more closely resembles that of humans than rodents. The lack of purinergic NMT in the IAS cannot be attributed to the absence of PDGFRα+ cells, P2Y1 receptors or SK3 channels. Rather, it appears to be due to poor coupling between P2Y1 receptors and SK3 channels on PDGFRα+ cells.
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Affiliation(s)
- C A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - M McKechnie
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - R J Brookfield
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - K I Hannigan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - K D Keef
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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Role of rho-kinase (ROCK) in tonic but not phasic contraction in the frog stomach smooth muscle. Life Sci 2018; 198:46-55. [PMID: 29455004 DOI: 10.1016/j.lfs.2018.02.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 02/14/2018] [Accepted: 02/15/2018] [Indexed: 01/17/2023]
Abstract
AIMS Rho/Rho-kinase (ROCK) signaling has extensively been shown to take part in mammalian smooth muscle contractions in response to diverse agents yet its role in the contraction of amphibian smooth muscle has not been investigated. Therefore, we aimed to explore any role of this pathway in the contractions of frog stomach smooth. MAIN METHODS The strips were prepared and suspended in organ baths filled with Ringer solution. Changes in the circular strips of the frog stomach muscle length were recorded isotonically with a force transducer in organ baths. KEY FINDINGS Carbachol (CCh) exerted both phasic and tonic contractions. In contrast, atropin abolished all types of contractions by CCh. The phasic contractions were suppressed by a Ca2+ channel blocker, nifedipine but not by the ROCK inhibitor, Y-27632. However, the tonic contractions were markedly attenuated by Y-27632. Selective M1 receptor blocker, pirenzepin, selective M3 receptor blocker and DAMP had no effects on CCh-elicited contractions. On the other hand, selective M2 receptor blocker, AF-DX suppressed all types of contractile activity by CCh. SIGNIFICANCE These data suggest that M2 receptor activation could mainly mediate CCh-induced phasic and tonic contractions, and ROCK seems to be involved in the CCh-induced tonic but not phasic contractions of the frog stomach smooth muscle.
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Boberg L, Szekeres FLM, Arner A. Signaling and metabolic properties of fast and slow smooth muscle types from mice. Pflugers Arch 2018; 470:681-691. [PMID: 29380055 PMCID: PMC5854729 DOI: 10.1007/s00424-017-2096-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 12/08/2017] [Accepted: 12/13/2017] [Indexed: 01/13/2023]
Abstract
This study aims to improve the classification of smooth muscle types to better understand their normal and pathological functional phenotypes. Four different smooth muscle tissues (aorta, muscular arteries, intestine, urinary bladder) with a 5-fold difference in maximal shortening velocity were obtained from mice and classified according to expression of the inserted myosin heavy chain (SMHC-B). Western blotting and quantitative PCR analyses were used to determine 15 metabolic and 8 cell signaling key components in each tissue. The slow muscle type (aorta) with a 12 times lower SMHC-B had 6-fold lower expression of the phosphatase subunit MYPT1, a 7-fold higher expression of Rhokinase 1, and a 3-fold higher expression of the PKC target CPI17, compared to the faster (urinary bladder) smooth muscle. The slow muscle had higher expression of components involved in glucose uptake and glycolysis (type 1 glucose transporter, 3 times; hexokinase, 13 times) and in gluconeogenesis (phosphoenolpyruvate carboxykinase, 43 times), but lower expression of the metabolic sensing AMP-activated kinase, alpha 2 isoform (5 times). The slow type also had higher expression of enzymes involved in lipid metabolism (hormone-sensitive lipase, 10 times; lipoprotein lipase, 13 times; fatty acid synthase, 6 times; type 2 acetyl-coenzyme A carboxylase, 8 times). We present a refined division of smooth muscle into muscle types based on the analysis of contractile, metabolic, and signaling components. Slow compared to fast smooth muscle has a lower expression of the deactivating phosphatase and upregulated Ca2+ sensitizing pathways and is more adapted for sustained glucose and lipid metabolism.
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Affiliation(s)
- Lena Boberg
- Department of Physiology and Pharmacology, Karolinska Institutet, v Eulers v 8, 171 77, Stockholm, SE, Sweden
| | | | - Anders Arner
- Department of Physiology and Pharmacology, Karolinska Institutet, v Eulers v 8, 171 77, Stockholm, SE, Sweden.
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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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Singh J, Mohanty I, Addya S, Phillips B, Mee Yong H, An SS, Penn RB, Rattan S. Role of differentially expressed microRNA-139-5p in the regulation of phenotypic internal anal sphincter smooth muscle tone. Sci Rep 2017; 7:1477. [PMID: 28469189 PMCID: PMC5431208 DOI: 10.1038/s41598-017-01550-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 03/27/2017] [Indexed: 12/19/2022] Open
Abstract
The present study focused on the role of microRNA-139-5p (miRNA-139-5p) in the regulation of basal tone in internal anal sphincter (IAS). Applying genome-wide miRNA microarrays on the phenotypically distinct smooth muscle cells (SMCs) within the rat anorectrum, we identified miRNA-139-5p as differentially expressed RNA repressor with highest expression in the purely phasic smooth muscle of anococcygeus (ASM) vs. the truly tonic smooth muscle of IAS. This pattern of miRNA-139-5p expression, previously shown to target ROCK2, was validated by target prediction using ingenuity pathway (IPA) and by qPCR analyses. Immunoblotting, immunocytochemistry (ICC), and functional assays using IAS tissues and cells subjected to overexpression/knockdown of miRNA-139-5p confirmed the inverse relationship between miRNA-139-5p and ROCK2 expressions/IAS tone. Overexpression of miRNA-139-5p caused a decrease, while knockdown by anti-miRNA-139-5p caused an increase in the IAS tone; these tissue contractile responses were confirmed by single-cell contraction using magnetic twisting cytometry (MTC). These findings suggest miRNA-139-5p is capable of significantly influencing the phenotypic tonicity in smooth muscle via ROCK2: a lack of tone in ASM may be associated with the suppression of ROCK2 by high expression of miRNA-139-5p, whereas basal IAS tone may be associated with the persistence of ROCK2 due to low expression of miRNA-139-5p.
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Affiliation(s)
- Jagmohan Singh
- Department of Medicine, Division of Gastroenterology & Hepatology, Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, PA, USA
| | - Ipsita Mohanty
- Department of Medicine, Division of Gastroenterology & Hepatology, Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, PA, USA
| | - Sankar Addya
- Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Benjamin Phillips
- Department of Surgery, Division of Colorectal Surgery, Thomas Jefferson University, Philadelphia, PA, USA
| | - Hwan Mee Yong
- Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Steven S An
- Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Raymond B Penn
- Center for Translational Medicine (RP), Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Satish Rattan
- Department of Medicine, Division of Gastroenterology & Hepatology, Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, PA, USA.
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Cobine CA, Hannah EE, Zhu MH, Lyle HE, Rock JR, Sanders KM, Ward SM, Keef KD. ANO1 in intramuscular interstitial cells of Cajal plays a key role in the generation of slow waves and tone in the internal anal sphincter. J Physiol 2017; 595:2021-2041. [PMID: 28054347 DOI: 10.1113/jp273618] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/16/2016] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS The internal anal sphincter develops tone important for maintaining high anal pressure and continence. Controversy exists regarding the mechanisms underlying tone development. We examined the hypothesis that tone depends upon electrical slow waves (SWs) initiated in intramuscular interstitial cells of Cajal (ICC-IM) by activation of Ca2+ -activated Cl- channels (ANO1, encoded by Ano1) and voltage-dependent L-type Ca2+ channels (CavL , encoded by Cacna1c). Measurement of membrane potential and contraction indicated that ANO1 and CavL have a central role in SW generation, phasic contractions and tone, independent of stretch. ANO1 expression was examined in wildtype and Ano1/+egfp mice with immunohistochemical techniques. Ano1 and Cacna1c expression levels were examined by quantitative PCR in fluorescence-activated cell sorting. ICC-IM were the predominant cell type expressing ANO1 and the most likely candidate for SW generation. SWs in ICC-IM are proposed to conduct to smooth muscle where Ca2+ entry via CavL results in phasic activity that sums to produce tone. ABSTRACT The mechanism underlying tone generation in the internal anal sphincter (IAS) is controversial. We examined the hypothesis that tone depends upon generation of electrical slow waves (SWs) initiated in intramuscular interstitial cells of Cajal (ICC-IM) by activation of Ca2+ -activated Cl- channels (encoded by Ano1) and voltage-dependent L-type Ca2+ channels (encoded by Cacna1c). Phasic contractions and tone in the IAS were nearly abolished by ANO1 and CavL antagonists. ANO1 antagonists also abolished SWs as well as transient depolarizations that persisted after addition of CavL antagonists. Tone development in the IAS did not require stretch of muscles, and the sensitivity of contraction to ANO1 antagonists was the same in stretched versus un-stretched muscles. ANO1 expression was examined in wildtype and Ano1/+egfp mice with immunohistochemical techniques. Dual labelling revealed that ANO1 expression could be resolved in ICC but not smooth muscle cells (SMCs) in the IAS and rectum. Ano1, Cacna1c and Kit gene expression were the same in extracts of IAS and rectum muscles. In IAS cells isolated with fluorescence-activated cell sorting, Ano1 expression was 26.5-fold greater in ICC than in SMCs while Cacna1c expression was only 2-fold greater in SMCs than in ICC. These data support a central role for ANO1 and CavL in the generation of SWs and tone in the IAS. ICC-IM are the probable cellular candidate for ANO1 currents and SW generation. We propose that ANO1 and CavL collaborate to generate SWs in ICC-IM followed by conduction to adjacent SMCs where phasic calcium entry through CavL sums to produce tone.
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Affiliation(s)
- C A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - E E Hannah
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - M H Zhu
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - H E Lyle
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - J R Rock
- Department of Anatomy, UCSF School of Medicine, San Francisco, CA, 94143, USA
| | - K M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - S M Ward
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - K D Keef
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
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Rattan S. Ca2+/calmodulin/MLCK pathway initiates, and RhoA/ROCK maintains, the internal anal sphincter smooth muscle tone. Am J Physiol Gastrointest Liver Physiol 2017; 312:G63-G66. [PMID: 27932502 PMCID: PMC5283903 DOI: 10.1152/ajpgi.00370.2016] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 11/28/2016] [Accepted: 12/02/2016] [Indexed: 02/07/2023]
Affiliation(s)
- Satish Rattan
- Department of Medicine, Division of Gastroenterology & Hepatology, Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania
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Abstract
Functions of the gastrointestinal tract include motility, digestion and absorption of nutrients. These functions are mediated by several specialized cell types including smooth muscle cells, neurons, interstitial cells and epithelial cells. In gastrointestinal diseases, some of the cells become degenerated or fail to accomplish their normal functions. Surgical resection of the diseased segments of the gastrointestinal tract is considered the gold-standard treatment in many cases, but patients might have surgical complications and quality of life can remain low. Tissue engineering and regenerative medicine aim to restore, repair, or regenerate the function of the tissues. Gastrointestinal tissue engineering is a challenging process given the specific phenotype and alignment of each cell type that colonizes the tract - these properties are critical for proper functionality. In this Review, we summarize advances in the field of gastrointestinal tissue engineering and regenerative medicine. Although the findings are promising, additional studies and optimizations are needed for translational purposes.
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Affiliation(s)
- Khalil N Bitar
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, 391 Technology Way NE, Winston Salem, North Carolina 27101, USA.,Department of Molecular Medicine and Translational Sciences, Wake Forest School of Medicine, 1 Medical Center Blvd, Winston Salem, North Carolina 27157, USA.,Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, 391 Technology Way NE, Winston Salem, North Carolina 27101, USA
| | - Elie Zakhem
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, 391 Technology Way NE, Winston Salem, North Carolina 27101, USA.,Department of Molecular Medicine and Translational Sciences, Wake Forest School of Medicine, 1 Medical Center Blvd, Winston Salem, North Carolina 27157, USA
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12
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Zhang CH, Wang P, Liu DH, Chen CP, Zhao W, Chen X, Chen C, He WQ, Qiao YN, Tao T, Sun J, Peng YJ, Lu P, Zheng K, Craige SM, Lifshitz LM, Keaney JF, Fogarty KE, ZhuGe R, Zhu MS. The molecular basis of the genesis of basal tone in internal anal sphincter. Nat Commun 2016; 7:11358. [PMID: 27101932 PMCID: PMC4844698 DOI: 10.1038/ncomms11358] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 03/16/2016] [Indexed: 02/06/2023] Open
Abstract
Smooth muscle sphincters exhibit basal tone and control passage of contents through organs such as the gastrointestinal tract; loss of this tone leads to disorders such as faecal incontinence. However, the molecular mechanisms underlying this tone remain unknown. Here, we show that deletion of myosin light-chain kinases (MLCK) in the smooth muscle cells from internal anal sphincter (IAS-SMCs) abolishes basal tone, impairing defecation. Pharmacological regulation of ryanodine receptors (RyRs), L-type voltage-dependent Ca2+ channels (VDCCs) or TMEM16A Ca2+-activated Cl− channels significantly changes global cytosolic Ca2+ concentration ([Ca2+]i) and the tone. TMEM16A deletion in IAS-SMCs abolishes the effects of modulators for TMEM16A or VDCCs on a RyR-mediated rise in global [Ca2+]i and impairs the tone and defecation. Hence, MLCK activation in IAS-SMCs caused by a global rise in [Ca2+]i via a RyR-TMEM16A-VDCC signalling module sets the basal tone. Targeting this module may lead to new treatments for diseases like faecal incontinence. The molecular basis of the basal tone generated by internal anal sphincters (IAS) is largely unknown. Here, the authors show that the tone arises from a global rise in intracellular Ca2+ in smooth muscle cells via a Ryanodine receptor-TMEM16A-L-type Ca2+ channel-MLC kinase pathway, suggesting a potential therapy for IAS motility disorders.
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Affiliation(s)
- Cheng-Hai Zhang
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China.,Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Pei Wang
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Dong-Hai Liu
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Cai-Ping Chen
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Wei Zhao
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Xin Chen
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Chen Chen
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Wei-Qi He
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China.,CAM-SU Genomic Resource Center, Soochow University, Suzhou 215123, China
| | - Yan-Ning Qiao
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Tao Tao
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Jie Sun
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Ya-Jing Peng
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Ping Lu
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Kaizhi Zheng
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Siobhan M Craige
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
| | - Lawrence M Lifshitz
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - John F Keaney
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
| | - Kevin E Fogarty
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Ronghua ZhuGe
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Min-Sheng Zhu
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China.,Innovation Center for Cardiovascular Disorders, Beijing 100029, China
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13
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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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14
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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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15
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Singh J, Kumar S, Rattan S. Bimodal effect of oxidative stress in internal anal sphincter smooth muscle. Am J Physiol Gastrointest Liver Physiol 2015; 309:G292-300. [PMID: 26138467 PMCID: PMC4556951 DOI: 10.1152/ajpgi.00125.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 06/29/2015] [Indexed: 01/31/2023]
Abstract
Changes in oxidative stress may affect basal tone and relaxation of the internal anal sphincter (IAS) smooth muscle in aging. We examined this issue by investigating the effects of the oxidative stress inducer 6-anilino-5,8-quinolinedione (LY-83583) in basal as well as U-46619-stimulated tone, and nonadrenergic, noncholinergic (NANC) relaxation in rat IAS. LY-83583, which works via generation of reactive oxygen species in living cells, produced a bimodal effect in IAS tone: lower concentrations (0.1 nM to 10 μM) produced a concentration-dependent increase, while higher concentrations (50-100 μM) produced a decrease in IAS tone. An increase in IAS tone by lower concentrations was associated with an increase in RhoA/Rho kinase (ROCK) activity. This was evident by the increase in RhoA/ROCK in the particulate fractions, in ROCK activity, and in the levels of phosphorylated (p) (Thr696)-myosin phosphatase target subunit 1 and p(Thr18/Ser19)-20-kDa myosin light chain. Conversely, higher concentrations of LY-83583 produced inhibitory effects on RhoA/ROCK. Interestingly, both the excitatory and inhibitory effects of LY-83583 in the IAS were reversed by superoxide dismutase. The excitatory effects of LY-83583 were found to resemble those with neuronal nitric oxide synthase (nNOS) inhibition by l-NNA, since it produced a significant increase in the IAS tone and attenuated NANC relaxation. These effects of LY-83583 and l-NNA were reversible by l-arginine. This suggests the role of nNOS inhibition and RhoA/ROCK activation in the increase in IAS tone by LY-83583. These data have important implications in the pathophysiology and therapeutic targeting of rectoanal disorders, especially associated with IAS dysfunction.
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Affiliation(s)
- Jagmohan Singh
- Division of Gastroenterology and Hepatology, Department of Medicine, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Sumit Kumar
- Division of Gastroenterology and Hepatology, Department of Medicine, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Satish Rattan
- Division of Gastroenterology and Hepatology, Department of Medicine, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania
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16
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Rego SL, Zakhem E, Orlando G, Bitar KN. Bioengineering functional human sphincteric and non-sphincteric gastrointestinal smooth muscle constructs. Methods 2015; 99:128-34. [PMID: 26314281 DOI: 10.1016/j.ymeth.2015.08.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 06/29/2015] [Accepted: 08/23/2015] [Indexed: 01/04/2023] Open
Abstract
Digestion and motility of luminal content through the gastrointestinal (GI) tract are achieved by cooperation between distinct cell types. Much of the 3 dimensional (3D) in vitro modeling used to study the GI physiology and disease focus solely on epithelial cells and not smooth muscle cells (SMCs). SMCs of the gut function either to propel and mix luminal contents (phasic; non-sphincteric) or to act as barriers to prevent the movement of luminal materials (tonic; sphincteric). Motility disorders including pyloric stenosis and chronic intestinal pseudoobstruction (CIPO) affect sphincteric and non-sphincteric SMCs, respectively. Bioengineering offers a useful tool to develop functional GI tissue mimics that possess similar characteristics to native tissue. The objective of this study was to bioengineer 3D human pyloric sphincter and small intestinal (SI) constructs in vitro that recapitulate the contractile phenotypes of sphincteric and non-sphincteric human GI SMCs. Bioengineered 3D human pylorus and circular SI SMC constructs were developed and displayed a contractile phenotype. Constructs composed of human pylorus SMCs displayed tonic SMC characteristics, including generation of basal tone, at higher levels than SI SMC constructs which is similar to what is seen in native tissue. Both constructs contracted in response to potassium chloride (KCl) and acetylcholine (ACh) and relaxed in response to vasoactive intestinal peptide (VIP). These studies provide the first bioengineered human pylorus constructs that maintain a sphincteric phenotype. These bioengineered constructs provide appropriate models to study motility disorders of the gut or replacement tissues for various GI organs.
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Affiliation(s)
- Stephen L Rego
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, United States.
| | - Elie Zakhem
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, United States; Department of Molecular Medicine and Translational Sciences, Wake Forest School of Medicine, Winston-Salem, NC, United States.
| | - Giuseppe Orlando
- Department of General Surgery, Wake Forest School of Medicine, Winston-Salem, NC, United States.
| | - Khalil N Bitar
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, United States; Department of Molecular Medicine and Translational Sciences, Wake Forest School of Medicine, Winston-Salem, NC, United States; Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Winston-Salem, NC, United States.
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17
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Rattan S, Singh J, Kumar S, Phillips B. Nature of extracellular signal that triggers RhoA/ROCK activation for the basal internal anal sphincter tone in humans. Am J Physiol Gastrointest Liver Physiol 2015; 308:G924-33. [PMID: 25882611 PMCID: PMC4451323 DOI: 10.1152/ajpgi.00017.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The extracellular signal that triggers activation of rho-associated kinase (RhoA/ROCK), the major molecular determinant of basal internal anal sphincter (IAS) smooth muscle tone, is not known. Using human IAS tissues, we identified the presence of the biosynthetic machineries for angiotensin II (ANG II), thromboxane A2 (TXA2), and prostaglandin F2α (PGF2α). These end products of the renin-angiotensin system (RAS) (ANG II) and arachidonic acid (TXA2 and PGF2α) pathways and their effects in human IAS vs. rectal smooth muscle (RSM) were studied. A multipronged approach utilizing immunocytochemistry, Western blot analyses, and force measurements was implemented. Additionally, in a systematic analysis of the effects of respective inhibitors along different steps of biosynthesis and those of antagonists, their end products were evaluated either individually or in combination. To further describe the molecular mechanism for the IAS tone via these pathways, we monitored RhoA/ROCK activation and its signal transduction cascade. Data showed characteristically higher expression of biosynthetic machineries of RAS and AA pathways in the IAS compared with the RSM. Additionally, specific inhibition of the arachidonic acid (AA) pathway caused ~80% decrease in the IAS tone, whereas that of RAS lead to ~20% decrease. Signal transduction studies revealed that the end products of both AA and RAS pathways cause increase in the IAS tone via activation of RhoA/ROCK. Both AA and RAS (via the release of their end products TXA2, PGF2α, and ANG II, respectively), provide extracellular signals which activate RhoA/ROCK for the maintenance of the basal tone in human IAS.
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Affiliation(s)
- Satish Rattan
- 1Department of Medicine, Division of Gastroenterology and Hepatology, Thomas Jefferson University, Philadelphia, Pennsylvania; and
| | - Jagmohan Singh
- 1Department of Medicine, Division of Gastroenterology and Hepatology, Thomas Jefferson University, Philadelphia, Pennsylvania; and
| | - Sumit Kumar
- 1Department of Medicine, Division of Gastroenterology and Hepatology, Thomas Jefferson University, Philadelphia, Pennsylvania; and
| | - Benjamin Phillips
- 2Department of Surgery, Division of Colorectal Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania
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18
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Rattan S, Ali M. Role of SM22 in the differential regulation of phasic vs. tonic smooth muscle. Am J Physiol Gastrointest Liver Physiol 2015; 308:G605-12. [PMID: 25617350 PMCID: PMC4385893 DOI: 10.1152/ajpgi.00360.2014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 01/16/2015] [Indexed: 01/31/2023]
Abstract
Preliminary proteomics studies between tonic vs. phasic smooth muscles identified three distinct protein spots identified to be those of transgelin (SM22). The latter was found to be distinctly downregulated in the internal anal sphincter (IAS) vs. rectal smooth muscle (RSM) SMC. The major focus of the present studies was to examine the differential molecular control mechanisms by SM22 in the functionality of truly tonic smooth muscle of the IAS vs. the adjoining phasic smooth muscle of the RSM. We monitored SMC lengths before and after incubation with pFLAG-SM22 (for SM22 overexpression), and SM22 small-interfering RNA. pFLAG-SM22 caused concentration-dependent and significantly greater relaxation in the IAS vs. the RSM SMCs. Conversely, temporary silencing of SM22 caused contraction in both types of the SMCs. Further studies revealed a significant reverse relationship between the levels of SM22 phosphorylation and the amount of SM22-actin binding in the IAS and RSM SMC. Data showed higher phospho-SM22 levels and decreased SM22-actin binding in the IAS, and reverse to be the case in the RSM SMCs. Experiments determining the mechanism for SM22 phosphorylation in these smooth muscles revealed that Y-27632 (Rho kinase inhibitor) but not Gö-6850 (protein kinase C inhibitor) caused concentration-dependent decreased phosphorylation of SM22. We speculate that SM22 plays an important role in the regulation of basal tone via Rho kinase-induced phosphorylation of SM22.
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Affiliation(s)
- Satish Rattan
- Division of Gastroenterology and Hepatology, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania; and
| | - Mehboob Ali
- 2The Research Institute at Nationwide Children's Hospital, Columbus, Ohio
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19
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Abstract
Signaling pathways regulate contraction of striated (skeletal and cardiac) and smooth muscle. Although these are similar, there are striking differences in the pathways that can be attributed to the distinct functional roles of the different muscle types. Muscles contract in response to depolarization, activation of G-protein-coupled receptors and other stimuli. The actomyosin fibers responsible for contraction require an increase in the cytosolic levels of calcium, which signaling pathways induce by promoting influx from extracellular sources or release from intracellular stores. Rises in cytosolic calcium stimulate numerous downstream calcium-dependent signaling pathways, which can also regulate contraction. Alterations to the signaling pathways that initiate and sustain contraction and relaxation occur as a consequence of exercise and pathophysiological conditions.
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Affiliation(s)
- Ivana Y Kuo
- Department of Pharmacology, School of Medicine, Yale University, New Haven, Connecticut 06520
| | - Barbara E Ehrlich
- Department of Pharmacology, School of Medicine, Yale University, New Haven, Connecticut 06520 Department of Cellular and Molecular Physiology, School of Medicine, Yale University, New Haven, Connecticut 06520
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20
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Krishna CV, Singh J, Kumar S, Rattan S. Heme oxygenase-1 upregulation modulates tone and fibroelastic properties of internal anal sphincter. Am J Physiol Gastrointest Liver Physiol 2014; 307:G595-601. [PMID: 25035109 PMCID: PMC4166724 DOI: 10.1152/ajpgi.00159.2014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 07/08/2014] [Indexed: 01/31/2023]
Abstract
A compromise in the internal anal sphincter (IAS) tone and fibroelastic properties (FEP) plays an important role in rectoanal incontinence. Herein, we examined the effects of heme oxygenase (HO)-1 upregulation on these IAS characteristics in young rats. We determined the effect of HO-1 upregulator hemin on HO-1 mRNA and protein expressions and on basal IAS tone and its FEP before and after HO-1 inhibitor tin protoporphyrin IX. For FEP, we determined the kinetics of the IAS smooth muscle responses, by the velocities of relaxation, and recovery of the IAS tone following 0 Ca(2+) and electrical field stimulation. To characterize the underlying signal transduction for these changes, we determined the effects of hemin on RhoA-associated kinase (RhoA)/Rho kinase (ROCK) II, myosin-binding subunit of myosin light chain phosphatase 1, fibronectin, and elastin expression levels. Hemin increased HO-1 mRNA and protein similar to the increases in the basal tone, and in the FEP of the IAS. Underlying mechanisms in the IAS characteristics are associated with increases in the genetic and translational expressions of RhoA/ROCKII, and elastin. Fibronectin expression levels on the other hand were found to be decreased following HO-1 upregulation. The results of our study show that the hemin/HO-1 system regulates the tone and FEP of IAS. The hemin/HO-1 system thus provides a potential target for the development of new interventions aimed at treatment of gastrointestinal motility disorders, specifically the age-related IAS dysfunction.
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Affiliation(s)
- Chadalavada Vijay Krishna
- Division of Gastroenterology and Hepatology, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Jagmohan Singh
- Division of Gastroenterology and Hepatology, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Sumit Kumar
- Division of Gastroenterology and Hepatology, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Satish Rattan
- Division of Gastroenterology and Hepatology, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
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21
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Boopathi E, Gomes C, Zderic SA, Malkowicz B, Chakrabarti R, Patel DP, Wein AJ, Chacko S. Mechanical stretch upregulates proteins involved in Ca2+ sensitization in urinary bladder smooth muscle hypertrophy. Am J Physiol Cell Physiol 2014; 307:C542-53. [PMID: 25031021 DOI: 10.1152/ajpcell.00033.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Partial bladder outlet obstruction (pBOO)-induced remodeling of bladder detrusor smooth muscle (DSM) is associated with the modulation of cell signals regulating contraction. We analyzed the DSM from obstructed murine urinary bladders for the temporal regulation of RhoA GTPase and Rho-activated kinase (ROCK), which are linked to Ca(2+) sensitization. In addition, the effects of equibiaxial cell stretch, a condition thought to be associated with pBOO-induced bladder wall smooth muscle hypertrophy and voiding frequency, on the expression of RhoA, ROCK, and C-kinase-activated protein phosphatase I inhibitor (CPI-17) were investigated. DSM from 1-, 3-, 7-, and 14-day obstructed male mice bladders and benign prostatic hyperplasia (BPH)-induced obstructed human bladders revealed overexpression of RhoA and ROCK-β at the mRNA and protein levels compared with control. Primary human bladder myocytes seeded onto type I collagen-coated elastic silicone membranes were subjected to cyclic equibiaxial stretch, mimicking the cellular mechanical stretch in the bladder in vivo, and analyzed for the expression of RhoA, ROCK-β, and CPI-17. Stretch caused a significant increase of RhoA, ROCKβ, and CPI-17 expression. The stretch-induced increase in CPI-17 expression occurs at the transcriptional level and is associated with CPI-17 promoter binding by GATA-6 and NF-κB, the transcription factors responsible for CPI-17 gene transcription. Cell stretch caused by bladder overdistension in pBOO is the likely mechanism for initiating overexpression of the signaling proteins regulating DSM tone.
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Affiliation(s)
- Ettickan Boopathi
- Division of Urology, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Cristiano Gomes
- Hospital das Clinicas, University of Sao Paulo School of Medicine, Sao Paulo, Brazil
| | - Stephen A Zderic
- Department of Urology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Bruce Malkowicz
- Division of Urology, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Ranjita Chakrabarti
- Division of Urology, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Darshan P Patel
- Division of Urology, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Alan J Wein
- Division of Urology, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Samuel Chacko
- Division of Urology, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania;
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22
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Hall KA, Ward SM, Cobine CA, Keef KD. Spatial organization and coordination of slow waves in the mouse anorectum. J Physiol 2014; 592:3813-29. [PMID: 24951622 DOI: 10.1113/jphysiol.2014.272542] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The internal anal sphincter (IAS) develops tone and is important for maintaining a high anal pressure while tone in the rectum is less. The mechanisms responsible for tone generation in the IAS are still uncertain. The present study addressed this question by comparing the electrical properties and morphology of the mouse IAS and distal rectum. The amplitude of tone and the frequency of phasic contractions was greater in the IAS than in rectum while membrane potential (Em) was less negative in the IAS than in rectum. Slow waves (SWs) were of greatest amplitude and frequency at the distal end of the IAS, declining in the oral direction. Dual microelectrode recordings revealed that SWs were coordinated over a much greater distance in the circumferential direction than in the oral direction. The circular muscle layer of the IAS was divided into five to eight 'minibundles' separated by connective tissue septa whereas few septa were present in the rectum. The limited coordination of SWs in the oral direction suggests that the activity in adjacent minibundles is not coordinated. Intramuscular interstitial cells of Cajal and platelet-derived growth factor receptor alpha-positive cells were present in each minibundle suggesting a role for one or both of these cells in SW generation. In summary, three important properties distinguish the IAS from the distal rectum: (1) a more depolarized Em; (2) larger and higher frequency SWs; and (3) the multiunit configuration of the muscle. All of these characteristics may contribute to greater tone generation in the IAS than in the distal rectum.
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Affiliation(s)
- K A Hall
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - S M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - C A Cobine
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - K D Keef
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
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23
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Singh J, Kumar S, Krishna CV, Rattan S. Aging-associated oxidative stress leads to decrease in IAS tone via RhoA/ROCK downregulation. Am J Physiol Gastrointest Liver Physiol 2014; 306:G983-91. [PMID: 24742984 PMCID: PMC4042111 DOI: 10.1152/ajpgi.00087.2014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Internal anal sphincter (IAS) tone plays an important role in rectoanal incontinence (RI). IAS tone may be compromised during aging, leading to RI in certain patients. We examined the influence of oxidative stress in the aging-associated decrease in IAS tone (AADI). Using adult (4-6 mo old) and aging (24-30 mo old) rats, we determined the effect of oxidative stress on IAS tone and the regulatory RhoA/ROCK signal transduction cascade. We determined the effect of the oxidative stress inducer LY83583, which produces superoxide anions (O2 (·-)), on basal and stimulated IAS tone before and after treatment of intact smooth muscle strips and smooth muscle cells with the O2 (·-) scavenger SOD. Our data showed that AADI was associated with a decrease in RhoA/ROCK expression at the transcriptional and translational levels. Oxidative stress with a LY83583-mediated decrease in IAS tone and relaxation of IAS smooth muscle cells was associated with a decrease in RhoA/ROCK signal transduction, which was reversible by SOD. In addition, LY83583 caused a significant decrease in IAS contraction produced by the RhoA activator and a known RhoA/ROCK agonist, U46619, that was also reversible by SOD. The inhibitory effects of LY83583 and the ROCK inhibitor Y27632 on the U46619-induced increase in IAS tone were similar. We conclude that an increase in oxidative stress plays an important role in AADI in the elderly and may be one of the underlying mechanisms of RI in certain aging patients.
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Affiliation(s)
| | | | | | - Satish Rattan
- Division of Gastroenterology and Hepatology, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
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Bitar KN, Raghavan S, Zakhem E. Tissue engineering in the gut: developments in neuromusculature. Gastroenterology 2014; 146:1614-24. [PMID: 24681129 PMCID: PMC4035447 DOI: 10.1053/j.gastro.2014.03.044] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 03/17/2014] [Accepted: 03/20/2014] [Indexed: 12/13/2022]
Abstract
The complexity of the gastrointestinal (GI) tract lies in its anatomy as well as in its physiology. Several different cell types populate the GI tract, adding to the complexity of cell sourcing for regenerative medicine. Each cell layer has a specialized function in mediating digestion, absorption, secretion, motility, and excretion. Tissue engineering and regenerative medicine aim to regenerate the specific layers mimicking architecture and recapitulating function. Gastrointestinal motility is the underlying program that mediates the diverse functions of the intestines, as an organ. Hence, the first logical step in GI regenerative medicine is the reconstruction of the tubular smooth musculature along with the drivers of their input, the enteric nervous system. Recent advances in the field of GI tissue engineering have focused on the use of scaffolding biomaterials in combination with cells and bioactive factors. The ability to innervate the bioengineered muscle is a critical step to ensure proper functionality. Finally, in vivo studies are essential to evaluate implant integration with host tissue, survival, and functionality. In this review, we focus on the tubular structure of the GI tract, tools for innervation, and, finally, evaluation of in vivo strategies for GI replacements.
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Affiliation(s)
- Khalil N. Bitar
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem NC 27101,Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Winston-Salem NC 27101
| | - Shreya Raghavan
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem NC 27101,Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Winston-Salem NC 27101
| | - Elie Zakhem
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem NC 27101,Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Winston-Salem NC 27101
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Rattan S. Smooth muscle-specific myosin phosphatase target subunit 1 (MYPT1): an important piece of the puzzle. Gastroenterology 2013; 145:1494-5. [PMID: 24172015 PMCID: PMC3888222 DOI: 10.1053/j.gastro.2013.07.055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 07/25/2013] [Indexed: 01/22/2023]
Affiliation(s)
- Satish Rattan
- Department of Medicine, Division of Gastroenterology & Hepatology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
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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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Singh J, Rattan S. Role of PKC and RhoA/ROCK pathways in the spontaneous phasic activity in the rectal smooth muscle. Am J Physiol Gastrointest Liver Physiol 2013; 304:G723-31. [PMID: 23413252 PMCID: PMC4073911 DOI: 10.1152/ajpgi.00473.2012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The role of PKC and RhoA/ROCK pathways in the phasic activities in the rectal smooth muscles (RSM) in the basal state is not known. We examined this issue by determining the effects of PKC inhibitors (calphostin C and Gö-6850) and a ROCK inhibitor (Y-27632) on the slow-rate (~3/min) and fast-rate (~25/min) phasic activities. We also examined the corresponding signal transduction cascades and the PKC and ROCK enzymatic activities in the RSM in the basal state. PKC inhibition with calphostin C and Gö-6850 (10(-5) M) caused a significant decrease (~25%) in slow-rate (but not fast-rate) phasic activity (monitored by frequency and amplitude of contractions) of the RSM. Conversely, ROCK inhibition with Y-27632 (10(-5) M) caused a significant decrease not only in slow-rate, but also fast-rate, phasic activity caused by ROCK inhibition in the RSM. Western blot analysis revealed that the PKC inhibition-induced decrease in RSM phasic activity was associated with decreases in PKCα translocation, phosphorylated (Thr(38)) PKC-potentiated inhibitor (CPI-17), and phosphorylated (Thr(18)/Ser(19)) 20-kDa myosin regulatory light chain. Conversely, decreases in the phasic activity in the RSM by ROCK inhibition were accompanied by the additional decrease in phosphorylated (Thr(696)) myosin phosphatase target subunit 1. Data show that while PKC and RhoA/ROCK pathways play a significant role in slow-rate high-amplitude spontaneous phasic activity, only the RhoA/ROCK pathway primarily mediates fast-rate low-amplitude phasic activity, in the RSM. Such knowledge is important in the understanding of the pathophysiology of large intestinal motility disorders. Relative contributions of the PKC vs. the RhoA/ROCK pathway in the phasic activity remain to be determined.
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Affiliation(s)
- Jagmohan Singh
- Division of Gastroenterology and Hepatology, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Satish Rattan
- Division of Gastroenterology and Hepatology, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
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28
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Bhetwal BP, An C, Baker SA, Lyon KL, Perrino BA. Impaired contractile responses and altered expression and phosphorylation of Ca(2+) sensitization proteins in gastric antrum smooth muscles from ob/ob mice. J Muscle Res Cell Motil 2013; 34:137-49. [PMID: 23576331 DOI: 10.1007/s10974-013-9341-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 03/27/2013] [Indexed: 12/21/2022]
Abstract
Diabetic gastroparesis is a common complication of diabetes, adversely affecting quality of life with symptoms of abdominal discomfort, nausea, and vomiting. The pathogenesis of this complex disorder is not well understood, involving abnormalities in the extrinsic and enteric nervous systems, interstitial cells of Cajal (ICCs), smooth muscles and immune cells. The ob/ob mouse model of obesity and diabetes develops delayed gastric emptying, providing an animal model for investigating how gastric smooth muscle dysfunction contributes to the pathophysiology of diabetic gastroparesis. Although ROCK2, MYPT1, and CPI-17 activities are reduced in intestinal motility disorders, their functioning has not been investigated in diabetic gastroparesis. We hypothesized that reduced expression and phosphorylation of the myosin light chain phosphatase (MLCP) inhibitory proteins MYPT1 and CPI-17 in ob/ob gastric antrum smooth muscles could contribute to the impaired antrum smooth muscle function of diabetic gastroparesis. Spontaneous and carbachol- and high K(+)-evoked contractions of gastric antrum smooth muscles from 7 to 12 week old male ob/ob mice were reduced compared to age- and strain-matched controls. There were no differences in spontaneous and agonist-evoked intracellular Ca(2+) transients and myosin light chain kinase expression. The F-actin:G-actin ratios were similar. Rho kinase 2 (ROCK2) expression was decreased at both ages. Basal and agonist-evoked MYPT1 and myosin light chain 20 phosphorylation, but not CPI-17 phosphorylation, was reduced compared to age-matched controls. These findings suggest that reduced MLCP inhibition due to decreased ROCK2 phosphorylation of MYPT1 in gastric antrum smooth muscles contributes to the antral dysmotility of diabetic gastroparesis.
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Affiliation(s)
- Bhupal P Bhetwal
- Department of Physiology & Cell Biology, Center of Biomedical Research Excellence, University of Nevada School of Medicine, CMM 203E-MS 0575, 1664 N Virginia St, Reno, NV 89557, USA
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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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Singh J, Rattan S. Bioengineered human IAS reconstructs with functional and molecular properties similar to intact IAS. Am J Physiol Gastrointest Liver Physiol 2012; 303:G713-22. [PMID: 22790596 PMCID: PMC3468534 DOI: 10.1152/ajpgi.00112.2012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Because of its critical importance in rectoanal incontinence, we determined the feasibility to reconstruct internal anal sphincter (IAS) from human IAS smooth muscle cells (SMCs) with functional and molecular attributes similar to the intact sphincter. The reconstructs were developed using SMCs from the circular smooth muscle layer of the human IAS, grown in smooth muscle differentiation media under sterile conditions in Sylgard-coated tissue culture plates with central Sylgard posts. The basal tone in the reconstructs and its changes were recorded following 0 Ca(2+), KCl, bethanechol, isoproterenol, protein kinase C (PKC) activator phorbol 12,13-dibutyrate, and Rho kinase (ROCK) and PKC inhibitors Y-27632 and Gö-6850, respectively. Western blot (WB), immunofluorescence (IF), and immunocytochemical (IC) analyses were also performed. The reconstructs developed spontaneous tone (0.68 ± 0.26 mN). Bethanechol (a muscarinic agonist) and K(+) depolarization produced contraction, whereas isoproterenol (β-adrenoceptor agonist) and Y-27632 produced a concentration-dependent decrease in the tone. Maximal decrease in basal tone with Y-27632 and Gö-6850 (each 10(-5) M) was 80.45 ± 3.29 and 17.76 ± 3.50%, respectively. WB data with the IAS constructs' SMCs revealed higher levels of RhoA/ROCK, protein kinase C-potentiated inhibitor or inhibitory phosphoprotein for myosin phosphatase (CPI-17), phospho-CPI-17, MYPT1, and 20-kDa myosin light chain vs. rectal smooth muscle. WB, IF, and IC studies of original SMCs and redispersed from the reconstructs for the relative distribution of different signal transduction proteins confirmed the feasibility of reconstruction of IAS with functional properties similar to intact IAS and demonstrated the development of myogenic tone with critical dependence on RhoA/ROCK. We conclude that it is feasible to bioengineer IAS constructs using human IAS SMCs that behave like intact IAS.
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Affiliation(s)
- Jagmohan Singh
- Division of Gastroenterology and Hepatology, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Satish Rattan
- Division of Gastroenterology and Hepatology, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
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31
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Rattan S, Singh J. RhoA/ROCK pathway is the major molecular determinant of basal tone in intact human internal anal sphincter. Am J Physiol Gastrointest Liver Physiol 2012; 302:G664-75. [PMID: 22241857 PMCID: PMC3330775 DOI: 10.1152/ajpgi.00430.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The knowledge of molecular control mechanisms underlying the basal tone in the intact human internal anal sphincter (IAS) is critical for the pathophysiology and rational therapy for a number of debilitating rectoanal motility disorders. We determined the role of RhoA/ROCK and PKC pathways by comparing the effects of ROCK- and PKC-selective inhibitors Y 27632 and Gö 6850 (10(-8) to 10(-4) M), respectively, on the basal tone in the IAS vs. the rectal smooth muscle (RSM). Western blot studies were performed to determine the levels of RhoA/ROCK II, PKC-α, MYPT1, CPI-17, and MLC(20) in the unphosphorylated and phosphorylated forms, in the IAS vs. RSM. Confocal microscopic studies validated the membrane distribution of ROCK II. Finally, to confirm a direct relationship, we examined the enzymatic activities and changes in the basal IAS tone and p-MYPT1, p-CPI-17, and p-MLC(20), before and after Y 27632 and Gö 6850. Data show higher levels of RhoA/ROCK II and related downstream signal transduction proteins in the IAS vs. RSM. In addition, data show a significant correlation between the active RhoA/ROCK levels, ROCK enzymatic activity, downstream proteins, and basal IAS tone, before and after ROCK inhibitor. From these data we conclude 1) RhoA/ROCK and downstream signaling are constitutively active in the IAS, and this pathway (in contrast with PKC) is the critical determinant of the basal tone in intact human IAS; and 2) RhoA and ROCK are potential therapeutic targets for a number of rectoanal motility disorders for which currently there is no satisfactory treatment.
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Affiliation(s)
- Satish Rattan
- Dept. of Medicine, Division of Gastroenterology & Hepatology, Philadelphia, PA 19107, USA.
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Bhetwal BP, An CL, Fisher SA, Perrino BA. Regulation of basal LC20 phosphorylation by MYPT1 and CPI-17 in murine gastric antrum, gastric fundus, and proximal colon smooth muscles. Neurogastroenterol Motil 2011; 23:e425-36. [PMID: 21883701 PMCID: PMC3173524 DOI: 10.1111/j.1365-2982.2011.01769.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP) govern myosin light chain (LC20) phosphorylation and smooth muscle contraction. Rho kinase (ROK) inhibits MLCP, resulting in greater LC20 phosphorylation and force generation at a given [Ca(2+) ](i) . Here, we investigate the role of ROK in regulating LC20 phosphorylation and spontaneous contractions of gastric fundus, gastric antrum, and proximal colon smooth muscles. METHODS Protein and phosphorylation levels were determined by western blotting. The effects of Y27632, nicardipine, and GF109203X on phosphorylation levels and contraction were measured. KEY RESULTS γ-Actin expression is similar in all three smooth muscles. LC20 and pS19 are highest, but ROK1 and ROK2 are lowest, in antrum and proximal colon smooth muscles. LZ +/- myosin phosphatase targeting subunit 1 (MYPT1), CPI-17, and pT696, pT853, and pT38 are highest in fundus and proximal colon smooth muscles. Myosin phosphatase-rho interacting protein (M-RIP) expression is lowest in fundus, and highest in antrum and proximal colon smooth muscles. Y27632 reduced pT853 in each smooth muscle, but reduced pT696 only in fundus smooth muscles. Nicardipine had no effect on pT38 in each smooth muscle, while GF109203X reduced pT38 in proximal colon and fundus smooth muscles. Y27632 or nicardipine reduced pS19 in proximal colon and fundus smooth muscles. Y27632 or nicardipine inhibited antrum and proximal colon smooth muscle spontaneous contractions, but only Y27632 reduced fundus smooth muscle tone. Zero external Ca(2+) relaxed each smooth muscle and abolished LC20 phosphorylation. CONCLUSIONS & INFERENCES Organ-specific mechanisms involving the MLCP interacting proteins LZ +/- MYPT1, M-RIP, and CPI-17 are critical to regulating basal LC20 phosphorylation in gastrointestinal smooth muscles.
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Affiliation(s)
- Bhupal P. Bhetwal
- Department of Physiology & Cell Biology, Center of Biomedical Research Excellence, University of Nevada School of Medicine, Reno, NV, USA
| | - Chang Long An
- Department of Physiology & Cell Biology, Center of Biomedical Research Excellence, University of Nevada School of Medicine, Reno, NV, USA
| | - Steven A. Fisher
- Departments of Medicine (Cardiology), and Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Brian A. Perrino
- Department of Physiology & Cell Biology, Center of Biomedical Research Excellence, University of Nevada School of Medicine, Reno, NV, USA
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Moffat LD, Brown SBA, Grassie ME, Ulke-Lemée A, Williamson LM, Walsh MP, MacDonald JA. Chemical genetics of zipper-interacting protein kinase reveal myosin light chain as a bona fide substrate in permeabilized arterial smooth muscle. J Biol Chem 2011; 286:36978-91. [PMID: 21880706 DOI: 10.1074/jbc.m111.257949] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Zipper-interacting protein kinase (ZIPK) has been implicated in Ca(2+)-independent smooth muscle contraction, although its specific role is unknown. The addition of ZIPK to demembranated rat caudal arterial strips induced an increase in force, which correlated with increases in LC(20) and MYPT1 phosphorylation. However, because of the number of kinases capable of phosphorylating LC(20) and MYPT1, it has proven difficult to identify the mechanism underlying ZIPK action. Therefore, we set out to identify bona fide ZIPK substrates using a chemical genetics method that takes advantage of ATP analogs with bulky substituents at the N(6) position and an engineered ZIPK capable of utilizing such substrates. (32)P-Labeled 6-phenyl-ATP and ZIPK-L93G mutant protein were added to permeabilized rat caudal arterial strips, and substrate proteins were detected by autoradiography following SDS-PAGE. Mass spectrometry identified LC(20) as a direct target of ZIPK in situ for the first time. Tissues were also exposed to 6-phenyl-ATP and ZIPK-L93G in the absence of endogenous ATP, and putative ZIPK substrates were identified by Western blotting. LC(20) was thereby confirmed as a direct target of ZIPK; however, no phosphorylation of MYPT1 was detected. We conclude that ZIPK is involved in the regulation of smooth muscle contraction through direct phosphorylation of LC(20).
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Affiliation(s)
- Lori D Moffat
- Smooth Muscle Research Group and the Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4Z6, Canada
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Yurtsever AS, Pektas M, Ozkur M, Un I, Erenmemisoglu A, Buyukafsar K. Proton pump inhibitors omeprazole, lansoprazole and pantoprazole induce relaxation in the rat lower oesophageal sphincter. J Pharm Pharmacol 2011; 63:1295-300. [PMID: 21899545 DOI: 10.1111/j.2042-7158.2011.01333.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Abstract
Objectives
We aimed to investigate effects of the proton pump inhibitors (PPIs) omeprazole, lansoprazole and pantoprazole, which are currently used for the treatment of hyperacidity and gastro-oesophageal reflux, on the reactivity of the isolated rat lower oesophageal sphincter.
Methods
Omeprazole, lansoprazole and pantoprazole (all 10–9–10–3m, cumulatively) were tested on carbachol-induced (10–6m) contraction. In addition, the effects of PPI preincubation (all 10–3m) on the contractions induced by cumulative carbachol (10−9–10−5m), angiotensin-2 (10−9–10–5m) or electrical field stimulation (EFS; 40 V, 32 Hz, 1 ms, 10 s) were assessed. Finally, the effects of PPI on the spontaneous contractile activity of the tissue were also evaluated.
Key findings
PPI relaxed precontracted lower oesophageal sphincter in a concentration-dependent manner and suppressed carbachol-, angiotensin- and EFS-induced contractions. Furthermore, PPI attenuated spontaneous contractile activity of the tissue.
Conclusions
Omeprazole, lansoprazole and pantoprazole had a suppressor effect on lower oesophageal sphincter contractions.
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Affiliation(s)
- A Sencer Yurtsever
- Department of Pharmacology, Medical Faculty, Mersin University Campus Yenişehir, Mersin, Turkey
| | - Mehtap Pektas
- Department of Pharmacology, Medical Faculty, Mersin University Campus Yenişehir, Mersin, Turkey
| | - Mehtap Ozkur
- Department of Pharmacology, Medical Faculty, Gaziantep University, Gaziantep, Turkey
| | - Ismail Un
- Department of Pharmacology, Medical Faculty, Mersin University Campus Yenişehir, Mersin, Turkey
| | - Aydın Erenmemisoglu
- Department of Pharmacology, Medical Faculty, Erciyes University, Kayseri, Turkey
| | - Kansu Buyukafsar
- Department of Pharmacology, Medical Faculty, Mersin University Campus Yenişehir, Mersin, Turkey
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de Godoy MAF, Rattan S. Role of rho kinase in the functional and dysfunctional tonic smooth muscles. Trends Pharmacol Sci 2011; 32:384-93. [PMID: 21497405 DOI: 10.1016/j.tips.2011.03.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 03/05/2011] [Accepted: 03/11/2011] [Indexed: 01/13/2023]
Abstract
Tonic smooth muscles play pivotal roles in the pathophysiology of debilitating diseases of the gastrointestinal and cardiovascular systems. Tonic smooth muscles differ from phasic smooth muscles in the ability to spontaneously develop myogenic tone. This ability has been primarily attributed to the local production of specific neurohumoral substances that can work in conjunction with calcium sensitization via signal transduction events associated with the Ras homolog gene family, member A (RhoA)/Rho-associated, coiled-coil containing protein kinase 2 (ROCK II) pathways. In this article, we discuss the molecular pathways involved in the myogenic properties of tonic smooth muscles, particularly the contribution of protein kinase C vs the RhoA/ROCK II pathway in the genesis of basal tone, pathophysiology and novel therapeutic approaches for certain gastrointestinal and cardiovascular diseases. Emerging evidence suggests that manipulation of RhoA/ROCK II activity through inhibitors or silencing of RNA interface techniques could represent a new therapeutic approach for various gastrointestinal and cardiovascular diseases.
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Affiliation(s)
- Márcio A F de Godoy
- Department of Medicine, Division of Gastroenterology and Hepatology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA, USA
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Rattan S. 3-Hydroxymethyl coenzyme A reductase inhibition attenuates spontaneous smooth muscle tone via RhoA/ROCK pathway regulated by RhoA prenylation. Am J Physiol Gastrointest Liver Physiol 2010; 298:G962-9. [PMID: 20378830 PMCID: PMC3774330 DOI: 10.1152/ajpgi.00034.2010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
RhoA prenylation may play an important step in the translocation of RhoA in the basal internal anal sphincter (IAS) smooth muscle tone. Statins inhibit downstream posttranslational RhoA prenylation by 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibition (HMGCRI). The role of statins in relation to RhoA prenylation in the pathophysiology of the spontaneously tonic smooth muscle has not been investigated. In the present studies, we determined the effect of classical HMGCRI simvastatin on the basal IAS tone and RhoA prenylation and in the levels of RhoA/Rho kinase (ROCK) in the cytosolic vs. membrane fractions of the smooth muscle. Simvastatin produced concentration-dependent decrease in the IAS tone (via direct actions at the smooth muscle cells). The decrease in the IAS tone by simvastatin was associated with the decrease in the prenylation of RhoA, as well as RhoA/ROCK in the membrane fractions of the IAS, in the basal state. The inhibitory effects of the HMGCRI were completely reversible by geranylgeranyltransferase substrate geranylgeranyl pyrophosphate. Relaxation of the IAS smooth muscle via HMGCRI simvastatin is mediated via the downstream decrease in the levels of RhoA prenylation and ROCK activity. Studies support the concept that RhoA prenylation leading to RhoA/ROCK translocation followed by activation is important for the basal tone in the IAS. Data suggest that the role of HMG-CoA reductase may go beyond cholesterol biosynthesis, such as the regulation of the smooth muscle tone. The studies have important implications in the pathophysiological mechanisms and in the novel therapeutic approaches for anorectal motility disorders.
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Affiliation(s)
- Satish Rattan
- 901 College, Dept. of Medicine, Div. of Gastroenterology & Hepatology, 1025 Walnut St., Philadelphia, PA 19107, USA.
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Wirth A. Rho kinase and hypertension. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1276-84. [PMID: 20460153 DOI: 10.1016/j.bbadis.2010.05.002] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 04/16/2010] [Accepted: 05/01/2010] [Indexed: 11/26/2022]
Abstract
Arterial hypertension is a multifactorial disease that is characterised by increased peripheral vascular resistance often accompanied by smooth muscle cell hypertrophy and proliferation. Rho kinases (ROCKs) are the most extensively studied effectors of the small G-protein RhoA and abnormalities in RhoA/ROCK signalling have been observed in various cardiovascular disease including hypertension. The RhoA/ROCK-pathway is a key player in different smooth muscle cell functions including contractility, proliferation and migration. Furthermore, there is extensive crosstalk between RhoA/ROCK- and NO-signalling. Therefore, not only ROCK inhibitors but also NO-donators or pleiotropic agents like statins exert their beneficial effects on the cardiovascular system at least in part via Rho/Rho-kinase.
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Affiliation(s)
- Angela Wirth
- Max-Planck-Institute for Heart and Lung Research, Dept. of Pharmacology, Ludwigstraße 43, 61231 Bad Nauheim, Germany.
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Cobine CA, Hennig GW, Bayguinov YR, Hatton WJ, Ward SM, Keef KD. Interstitial cells of Cajal in the cynomolgus monkey rectoanal region and their relationship to sympathetic and nitrergic nerves. Am J Physiol Gastrointest Liver Physiol 2010; 298:G643-56. [PMID: 20150245 PMCID: PMC2867417 DOI: 10.1152/ajpgi.00260.2009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The morphology of interstitial cells of Cajal (ICC) in the circular muscle layer of the cynomolgus monkey internal anal sphincter (IAS) and rectum and their relationship to sympathetic and nitrergic nerves were compared by dual-labeling immunohistochemistry. Contractile studies confirmed that nitrergic nerves participate in neural inhibition in both regions whereas sympathetic nerves serve as excitatory motor nerves only in the IAS. Muscle bundles extended from myenteric to submucosal edge in rectum but in the IAS bundles were further divided into "minibundles" each surrounded by connective tissue. Dual labeling of KIT and smooth muscle myosin revealed KIT-positive stellate-shaped ICC (ICC-IAS) within each minibundle. In the rectum intramuscular ICC (ICC-IM) were spindle shaped whereas stellate-shaped ICC were located at the myenteric surface (ICC-MY). ICC were absent from both the myenteric and submucosal surfaces of the IAS. Nitrergic nerves (identified with anti-neuronal nitric oxide synthase antibodies or NADPH diaphorase activity) and sympathetic nerves (identified with anti-tyrosine hydroxylase antibody) each formed a plexus at the myenteric surface of the rectum but not the IAS. Intramuscular neuronal nitric oxide synthase- and tyrosine hydroxylase-positive fibers were present in both regions but were only closely associated with ICC-IM in rectum. Minimal association was also noted between ICC-IAS and cells expressing the nonspecific neuronal marker PGP9.5. In conclusion, the morphology of rectal ICC-IM and ICC-MY is similar to that described elsewhere in the gastrointestinal tract whereas ICC-IAS are unique. The distribution of stellate-shaped ICC-IAS throughout the musculature and their absence from both the myenteric and submucosal surfaces suggest that ICC-IAS may serve as pacemaker cells in this muscle whereas their limited relationship to nerves suggests that they are not involved in neuromuscular transmission. Additionally, the presence of numerous minibundles, each containing both ICC-IAS and nerves, suggests that this muscle functions as a multiunit type muscle.
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Affiliation(s)
- C. A. Cobine
- Department of Physiology and Cell Biology University of Nevada, Reno, Nevada
| | - G. W. Hennig
- Department of Physiology and Cell Biology University of Nevada, Reno, Nevada
| | - Y. R. Bayguinov
- Department of Physiology and Cell Biology University of Nevada, Reno, Nevada
| | - W. J. Hatton
- Department of Physiology and Cell Biology University of Nevada, Reno, Nevada
| | - S. M. Ward
- Department of Physiology and Cell Biology University of Nevada, Reno, Nevada
| | - K. D. Keef
- Department of Physiology and Cell Biology University of Nevada, Reno, Nevada
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Kawaguchi T, Satoh KI, Kuji A, Joh S. Features of distinct contractions induced with a high and a low concentration of KCl, noradrenaline, and histamine in swine lingual artery. Naunyn Schmiedebergs Arch Pharmacol 2010; 381:107-20. [PMID: 20054523 DOI: 10.1007/s00210-009-0486-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Accepted: 12/11/2009] [Indexed: 12/23/2022]
Abstract
We investigated the features of swine lingual artery contraction induced with different strengths of stimulation. Endothelium-denuded artery rings were contracted with two concentrations of KCl, noradrenaline, and histamine with or without Y-27632, sodium nitroprusside (SNP), 2,2-diphenyl-1,3,2-oxaza-borolidine internal salt (2- APB), and extracellular Ca2+. While stored at 5 degrees C up to 3 days, artery rings remained active to strong stimulation but became inactive to weak stimulation if prior warming was lacking. Artery rings contracted slowly and progressively to weak stimulation but rapidly to strong stimulation and then kept a plateau or slightly relaxed. Y-27632, SNP, and 2-APB, irrespective of extracellular Ca2+, attenuated weak-stimulation-induced contractions to much greater extents except that 2-APB similarly diminished contractions to both noradrenaline concentrations. Without extracellular Ca2+, transitory contractions occurred with one peak to strong stimulation and two small peaks to weak stimulation, though one full peak to both noradrenaline concentrations. Artery rings lost stimulant responsiveness when extracellular Ca2+ was absent, but subsequent Ca2+ reintroduction without coexisting stimulant triggered transient contractions, which were as large as contractions to weak stimulation with extracellular Ca2+ and ceased with Y-27632, SNP, and 2-APB. These results collectively suggest that, in the lingual artery, its contraction properties shift coupling with strengths of both receptor- and voltage-mediated stimulation, with the tonic-like component being dominant in weak-stimulation-induced contraction.
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Affiliation(s)
- Takaki Kawaguchi
- Department of Biochemistry, School of Dentistry, Iwate Medical University, Morioka 020-8505, Japan.
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RATTAN SATISH, PHILLIPS BENJAMINR, MAXWELL PINCKNEYJ. RhoA/Rho-kinase: pathophysiologic and therapeutic implications in gastrointestinal smooth muscle tone and relaxation. Gastroenterology 2010; 138:13-8.e1-3. [PMID: 19931260 PMCID: PMC5599165 DOI: 10.1053/j.gastro.2009.11.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- SATISH RATTAN
- Department of Medicine, Division of Gastroenterology & Hepatology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA
| | - BENJAMIN R. PHILLIPS
- Department of Surgery, Division of Colon and Rectal Surgery, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA
| | - PINCKNEY J. MAXWELL
- Department of Surgery, Division of Colon and Rectal Surgery, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA
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Zhang WC, Peng YJ, Zhang GS, He WQ, Qiao YN, Dong YY, Gao YQ, Chen C, Zhang CH, Li W, Shen HH, Ning W, Kamm KE, Stull JT, Gao X, Zhu MS. Myosin light chain kinase is necessary for tonic airway smooth muscle contraction. J Biol Chem 2009; 285:5522-31. [PMID: 20018858 DOI: 10.1074/jbc.m109.062836] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Different interacting signaling modules involving Ca(2+)/calmodulin-dependent myosin light chain kinase, Ca(2+)-independent regulatory light chain phosphorylation, myosin phosphatase inhibition, and actin filament-based proteins are proposed as specific cellular mechanisms involved in the regulation of smooth muscle contraction. However, the relative importance of specific modules is not well defined. By using tamoxifen-activated and smooth muscle-specific knock-out of myosin light chain kinase in mice, we analyzed its role in tonic airway smooth muscle contraction. Knock-out of the kinase in both tracheal and bronchial smooth muscle significantly reduced contraction and myosin phosphorylation responses to K(+)-depolarization and acetylcholine. Kinase-deficient mice lacked bronchial constrictions in normal and asthmatic airways, whereas the asthmatic inflammation response was not affected. These results indicate that myosin light chain kinase acts as a central participant in the contractile signaling module of tonic smooth muscle. Importantly, contractile airway smooth muscles are necessary for physiological and asthmatic airway resistance.
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Affiliation(s)
- Wen-Cheng Zhang
- Model Animal Research Center of Nanjing University and MOE Key Lab of Model Animal for Disease Study, Nanjing 210061, China
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Singh J, Mehendiratta V, Del Galdo F, Jimenez SA, Cohen S, DiMarino AJ, Rattan S. Immunoglobulins from scleroderma patients inhibit the muscarinic receptor activation in internal anal sphincter smooth muscle cells. Am J Physiol Gastrointest Liver Physiol 2009; 297:G1206-13. [PMID: 19779020 PMCID: PMC2850093 DOI: 10.1152/ajpgi.00286.2009] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Systemic sclerosis (SSc) IgGs affecting the M(3)-muscarinic receptor (M(3)-R) have been proposed to be responsible for the gastrointestinal (GI) dysmotility in this disease. However, the effect of SSc IgGs on smooth muscle cell (SMC) function has not been studied. We determined the effect of SSc IgGs on the muscarinic receptor activation by bethanechol (BeCh; methyl derivate of carbachol) in SMC and smooth muscle strips from rat internal anal sphincter. IgGs were purified from GI-symptomatic SSc patients and normal volunteers, with protein G-Sepharose columns. SMC lengths were determined via computerized digital micrometry. The presence of M(3)-R and IgG-M(3)-R complex was determined by Western blot. IgGs from SSc patients but not from normal volunteers caused significant and concentration-dependent inhibition of BeCh response (P < 0.05). The maximal shortening of 22.2 +/- 1.2% caused by 10(-4) M BeCh was significantly attenuated to 8.3 +/- 1.2% by 1 mg/ml of SSc IgGs (P < 0.05). Experiments performed in smooth muscle strips revealed a similar effect of SSc IgG that was fully reversible. In contrast to the effect on BeCh, the SSc IgGs caused no significant effect (P > 0.05) on K(+) depolarization and alpha(1)-adrenoceptor activation by phenylephrine. Western blot studies revealed the specific presence of SSc IgG-M(3)-R complex. SSc IgGs attenuated M(3)-R activation, which was reversible with antibody removal. These data suggest that SSc GI dysmotility may be caused by autoantibodies that inhibit the muscarinic neurotransmission. Future treatment of SSc patients may be directed at the removal or neutralization of these antibodies.
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Affiliation(s)
- Jagmohan Singh
- 1Department of Medicine, Division of Gastroenterology and Hepatology, and
| | | | - Francesco Del Galdo
- 2Scleroderma Center and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Sergio A. Jimenez
- 2Scleroderma Center and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania
| | | | | | - Satish Rattan
- 1Department of Medicine, Division of Gastroenterology and Hepatology, and
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Okano M, Uchikawa Y, Tanaka N, Mutoh J, Ohkura M, Hisa H, Yamamoto R. Rho-kinase, but not protein kinase C, is involved in generation of the spontaneous tone in the resting phase of the isolated pig iris sphincter muscle. Curr Eye Res 2009; 34:177-83. [PMID: 19274524 DOI: 10.1080/02713680802652175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE The purpose of the present study was to clarify the role of Rho-kinase and/or protein kinase C in the resting tension of the isolated pig iris sphincter muscle. MATERIALS AND METHODS The motor activity of the isolated pig iris sphincter muscle was measured isometrically. RESULTS EGTA, a chelator of extracellular Ca(2+), significantly reduced the resting tension. Y27632, a Rho-kinase inhibitor, significantly reduced the resting tension in a concentration-dependent manner. The resting tension diminished by Y27632 was significantly recovered by the addition of calyculin A, a myosin light chain phosphatase (MLCP) inhibitor, in a concentration-dependent manner. GF109203X, a protein kinase C inhibitor, had no effect on the resting tension. CONCLUSION These results suggest that, in the isolated pig iris sphincter muscle, Rho-kinase plays an important role in the generation of spontaneous tone in the resting phase via the inhibition of MLCP activity.
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Affiliation(s)
- Mayumi Okano
- Department of Orthoptics and Visual Sciences, School of Health Sciences, Kyushu University of Health and Welfare, Nobeoka, Miyazaki, Japan
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Park SY, Song HJ, Sohn UD. Participation of Rho-associated kinase in electrical stimulated and acetylcholine-induced contraction of feline esophageal smooth muscle. Eur J Pharmacol 2009; 607:220-5. [PMID: 19239907 DOI: 10.1016/j.ejphar.2009.02.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 01/21/2009] [Accepted: 02/09/2009] [Indexed: 11/18/2022]
Abstract
The RhoA/Rho-associated kinase (ROCK) signaling pathway has been known to play a critical role in Ca(2+)-sensitization of smooth muscle contraction. In this study, we investigated the role of ROCK in feline esophageal body smooth muscle contraction induced by electrical field stimulation and exogenous acetylcholine in vitro. Y-27632 [(+)-(R)-trans-4-(1-aminoethyl)-(4-pyridyl) cyclohexanecarboxamide dihydrochloride], ROCK inhibitor, and specific antibodies to ROCK1 and ROCK2 proteins, which are two isoforms of ROCK, were used. Electrical field stimulation induced off-contraction and on-contraction in the presence of N(G)-nitro-L-arginine methylester, originating from the cholinergic nerve. Y-27632 inhibited both excitatory contractions in a concentration-dependent manner. Exogenous acetylcholine concentration-dependently induced two types of contractions: an initial contraction which occurred immediately after the addition of acetylcholine during short periods, and a sustained contraction which sluggishly continued after the initial contraction. Maximal initial and sustained contractions were reached at 10(-5) M acetylcholine. Y-27632 significantly inhibited both acetylcholine-induced contractions in a concentration-dependent manner. Western blot analysis revealed that acetylcholine maximally increased the level of phosphorylation in the 20 kDa regulatory light chain of myosin II (MLC(20)) at Ser(19) from 0.25 min to 1 min, and then declined after 2 min. The level changes of MLC(20) phosphorylation during the 5 min paralleled with those of acetylcholine-induced contractions. The expression of ROCK1 and ROCK2 in membrane fractions of muscle was increased by acetylcholine; more specifically, ROCK2 continually expressed up to 5 min. Taken together, ROCK may be involved in neural-evoked and acetylcholine-induced contraction via translocation to the membrane in feline esophageal smooth muscle.
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Affiliation(s)
- Sun Young Park
- Department of Pharmacology, College of Pharmacy, Chung-Ang University, Seoul 156-756, Republic of Korea
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Dhaese I, Lefebvre RA. Myosin light chain phosphatase activation is involved in the hydrogen sulfide-induced relaxation in mouse gastric fundus. Eur J Pharmacol 2009; 606:180-6. [PMID: 19374871 DOI: 10.1016/j.ejphar.2009.01.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Revised: 11/24/2008] [Accepted: 01/09/2009] [Indexed: 01/09/2023]
Abstract
The relaxant effect of hydrogen sulfide (H(2)S) in the vascular tree is well established but its influence and mechanism of action in gastrointestinal smooth muscle was hardly investigated. The influence of H(2)S on contractility in mouse gastric fundus was therefore examined. Sodium hydrogen sulfide (NaHS; H(2)S donor) was administered to prostaglandin F(2alpha) (PGF(2alpha))-contracted circular muscle strips of mouse gastric fundus, before and after incubation with interfering drugs. NaHS caused a concentration-dependent relaxation of the pre-contracted mouse gastric fundus strips. The K(+) channels blockers glibenclamide, apamin, charybdotoxin, 4-aminopyridin and barium chloride had no influence on the NaHS-induced relaxation. The relaxation by NaHS was also not influenced by L-NAME, ODQ and SQ 22536, inhibitors of the cGMP and cAMP pathway, by nerve blockers capsazepine, omega-conotoxin and tetrodotoxin or by several channel and receptor blockers (ouabain, nifedipine, 2-aminoethyl diphenylborinate, ryanodine and thapsigargin). The myosin light chain phosphatase (MLCP) inhibitor calyculin-A reduced the NaHS-induced relaxation, but the Rho-kinase inhibitor Y-27632 had no influence. We show that NaHS is able to relax PGF(2alpha)-contracted mouse gastric fundus strips. The results suggest that in the mouse gastric fundus, H(2)S causes relaxation at least partially via activation of MLCP.
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Affiliation(s)
- Ingeborg Dhaese
- Heymans Institute of Pharmacology, Ghent University, Ghent, Belgium
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Hartman Bakken B, Herrera M LG, Carroll RM, Ayala-Berdón J, Schondube JE, Martínez Del Rio C. A nectar-feeding mammal avoids body fluid disturbances by varying renal function. Am J Physiol Renal Physiol 2008; 295:F1855-63. [PMID: 18945828 DOI: 10.1152/ajprenal.90349.2008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
To maintain water and electrolyte balance, nectar-feeding vertebrates oscillate between two extremes: avoiding overhydration when feeding and preventing dehydration during fasts. Several studies have examined how birds resolve this osmoregulatory dilemma, but no data are available for nectar-feeding mammals. In this article, we 1) estimated the ability of Pallas's long-tongued bats (Glossophaga soricina; Phyllostomidae) to dilute and concentrate urine and 2) examined how water intake affected the processes that these bats use to maintain water balance. Total urine osmolality in water- and salt-loaded bats ranged between 31 +/- 37 mosmol/kgH(2)O (n = 6) and 578 +/- 56 mosmol/kgH(2)O (n = 2), respectively. Fractional water absorption in the gastrointestinal tract was not affected by water intake rate. As a result, water flux, body water turnover, and renal water load all increased with increasing water intake. Despite these relationships, glomerular filtration rate (GFR) was not responsive to water loading. To eliminate excess water, Pallas's long-tongued bats increased water excretion rate by reducing fractional renal water reabsorption. We also found that rates of total evaporative water loss increased with increasing water intake. During their natural daytime fast, mean GFR in Pallas's long-tongued bats was 0.37 ml/h (n = 10). This is approximately 90% lower than the GFR we measured in fed bats. Our findings 1) suggest that Pallas's long-tongued bats do not have an exceptional urine-diluting or -concentrating ability and 2) demonstrate that the bats eliminate excess ingested water by reducing renal water reabsorption and limit urinary water loss during fasting periods by reducing GFR.
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Affiliation(s)
- Bradley Hartman Bakken
- Dept. of Forest and Wildlife Ecology, Univ. of Wisconsin-Madison, 120 Russell Labs, 1630 Linden Dr., Madison, WI 53706, USA.
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Myosin light chain kinase is central to smooth muscle contraction and required for gastrointestinal motility in mice. Gastroenterology 2008; 135:610-20. [PMID: 18586037 PMCID: PMC2648853 DOI: 10.1053/j.gastro.2008.05.032] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Revised: 04/24/2008] [Accepted: 05/08/2008] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Smooth muscle is essential for maintaining homeostasis for many body functions and provides adaptive responses to stresses imposed by pathologic disorders. Identified cell signaling networks have defined many potential mechanisms for initiating smooth muscle contraction with or without myosin regulatory light chain (RLC) phosphorylation by myosin light chain kinase (MLCK). We generated tamoxifen-inducible and smooth muscle-specific MLCK knockout (KO) mice and provide direct loss-of-function evidence that shows the primary importance of MLCK in phasic smooth muscle contractions. METHODS We used the Cre-loxP system to establish Mlck floxed mice in which exons 23, 24, and 25 were flanked by 2 loxP sites. Smooth muscle-specific MLCK KO mice were generated by crossing Mlck floxed mice with SM-CreER(T2) (ki) mice followed by tamoxifen treatment. The phenotype was assessed by histologic, biochemical, molecular, cell biological, and physiologic analyses. RESULTS Targeted deletion of MLCK in adult mouse smooth muscle resulted in severe gut dysmotility characterized by weak peristalsis, dilation of the digestive tract, and reduction of feces excretion and food intake. There was also abnormal urinary bladder function and lower blood pressure. Isolated muscles showed a loss of RLC phosphorylation and force development induced by K(+)-depolarization. The kinase knockout also markedly reduced RLC phosphorylation and force development with acetylcholine which activates Ca(2+)-sensitizing signaling pathways. CONCLUSIONS MLCK and its phosphorylation of RLC are required physiologically for smooth muscle contraction and are essential for normal gastrointestinal motility.
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Abstract
Smooth muscle cells (SMC) make up the muscular portion of the gastrointestinal (GI) tract from the distal oesophagus to the internal anal sphincter. Coordinated contractions of these cells produce the motor patterns of GI motility. Considerable progress was made during the last 20 years to understand the basic mechanisms controlling excitation-contraction (E-C) coupling. The smooth muscle motor is now understood in great molecular detail, and much has been learned about the mechanisms that deliver and recover Ca2+ during contractions. The majority of Ca2+ that initiates contractions comes from the external solution and is supplied by voltage-dependent Ca2+ channels (VDCC). VDCC are regulated largely by the effects of K+ and non-selective cation conductances (NSCC) on cell membrane potential and excitability. Ca2+ entry is supplemented by release of Ca2+ from IP(3) receptor-operated stores and by mechanisms that alter the sensitivity of the contractile apparatus to changes in cytoplasmic Ca2+. Molecular studies of the regulation of smooth muscle have been complicated by the plasticity of SMC and difficulties in culturing these cells without dramatic phenotypic changes. Major questions remain to be resolved regarding the details of E-C coupling in human GI smooth muscles. New discoveries regarding molecular expression that give GI smooth muscle their unique properties, the phenotypic changes that occur in SMC in GI motor disorders, tissue engineering approaches to repair or replace defective muscular regions, and molecular manipulations of GI smooth muscles in animals models and in cell culture will be topics for exciting investigations in the future.
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Affiliation(s)
- K M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA.
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Rattan S, Patel CA. Selectivity of ROCK inhibitors in the spontaneously tonic smooth muscle. Am J Physiol Gastrointest Liver Physiol 2008; 294:G687-93. [PMID: 18187514 DOI: 10.1152/ajpgi.00501.2007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The selectivity of different Rho kinase (ROCK) inhibitors in the spontaneously tonic smooth muscle has not been investigated. We examined this issue using Y-27632 [(R)-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexanecarbox anecarboxamide, 2HCl], H-1152 [(S)-(+)-(2-methyl-5-isoquinolinyl) sulfonylhomopiperazine, 2HCl], HA-1077 [(5 isoquinolinesulfonyl) homopiperazine, 2HCl], and ROCK inhibitor II [N-(4-pyridyl)-N'-(2,4,6-trichlorophenyl)urea]. We compared these inhibitors in the spontaneously tonic smooth muscle of the internal anal sphincter (IAS). ROCK, protein kinase C (PKC), and myosin light chain kinase (MLCK) activities were determined in the IAS, before and after different ROCK inhibitors. Y-27632 and H-1152 were approximately 30-fold more potent in the IAS (IC(50): 4.4 x 10(-7) and 7.9 x 10(-8) M, respectively) vs. the phasic rectal smooth muscle (RSM) (IC(50): 1.3 x 10(-5) and 2.5 x 10(-6) M, respectively). HA-1077 and ROCK inhibitor II were equipotent in the IAS vs. RSM. In the IAS, H-1152 was the most potent whereas ROCK inhibitor II is the least. Y-27632 and H-1152 caused concentration-dependent decrease in the IAS tone that correlates directly with the decreases in ROCK activity, without significant effect in the PKC and MLCK activities. This specifically selective correlation between ROCK activity and decrease in the IAS tone was absent in the case of HA-1077 and ROCK inhibitor II, which also inhibited PKC and MLCK. We conclude that the IAS tone is critically dependent on ROCK activity, and H-1152 and Y-27632 are the most selective and potent ROCK inhibitors in the IAS.
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Affiliation(s)
- Satish Rattan
- Department of Medicine, Division of Gastroenterology and Hepatology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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de Godoy MAF, Rattan S. Role of phospholipase A2 (group I secreted) in the genesis of basal tone in the internal anal sphincter smooth muscle. Am J Physiol Gastrointest Liver Physiol 2007; 293:G979-86. [PMID: 17717042 DOI: 10.1152/ajpgi.00310.2007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The role of phospholipase A(2) (PLA(2)) in the genesis of basal tone in the internal anal sphincter (IAS) is not known. We determined the effects of PLA(2) and inhibitors on the basal tone and intraluminal pressures (IASP) in the rat IAS vs. rectal smooth muscles (RSM). In addition, we determined the correlations between the IAS tone, PLA(2) levels, and the actual enzymatic activity. Inhibition of PLA(2) by 4-bromophenacyl bromide (universal inhibitor of PLA(2)) and MJ33 [selective inhibitor of secreted isoform of PLA(2) (sPLA(2))] caused concentration-dependent decrease in the IAS tone and in the IASP. Maximal decreases in the IAS tone and IASP by 4-bromophenacyl bromide and MJ33 were 58.8 +/- 6.9 and 51.5 +/- 6.3%, and 66.7 +/- 5.1 and 79.8 +/- 8.2%, respectively. The sPLA(2) inhibitors were approximately 100 times more potent in decreasing the IASP than the mean blood pressure. Conversely, the selective inhibitors of the cytosolic and calcium-independent PLA(2) arachidonyl trifluoromethyl ketone and bromoenol lactone, respectively, produced no significant effect. The IAS had characteristically higher levels of sPLA(2) activity (26.5 +/- 4.9 micromol.min(-1).ml(-1)) vs. the RSM (3.2 +/- 0.4 micromol.min(-1).ml(-1)), and higher levels of sPLA(2) as shown by Western blot and RT-PCR. Interestingly, administration of sPLA(2) transformed RSM into the tonic smooth muscle like that of the IAS: it developed basal tone and relaxed in response to the electrical field stimulation. From the present data, we conclude that sPLA(2) plays a critical role in the genesis of tone in the IAS. PLA(2) inhibitors may provide potential therapeutic target for treating anorectal motility disorders.
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Affiliation(s)
- Márcio A F de Godoy
- Department of Medicine, Division of Gastroenterology and Hepatology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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