scholarly journals microRNA overexpression in slow transit constipation leads to reduced NaV1.5 current and altered smooth muscle contractility

Gut ◽  
2019 ◽  
Vol 69 (5) ◽  
pp. 868-876
Author(s):  
Amelia Mazzone ◽  
Peter R Strege ◽  
Simon J Gibbons ◽  
Constanza Alcaino ◽  
Vikram Joshi ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Current Density ◽  
Ex Vivo ◽  
Slow Transit Constipation ◽  
Organotypic Cultures ◽  
Smooth Muscle Contractility ◽  
Slow Transit ◽  
Transit Constipation ◽  
Muscularis Externa

ObjectiveThis study was designed to evaluate the roles of microRNAs (miRNAs) in slow transit constipation (STC).DesignAll human tissue samples were from the muscularis externa of the colon. Expression of 372 miRNAs was examined in a discovery cohort of four patients with STC versus three age/sex-matched controls by a quantitative PCR array. Upregulated miRNAs were examined by quantitative reverse transcription qPCR (RT-qPCR) in a validation cohort of seven patients with STC and age/sex-matched controls. The effect of a highly differentially expressed miRNA on a custom human smooth muscle cell line was examined in vitro by RT-qPCR, electrophysiology, traction force microscopy, and ex vivo by lentiviral transduction in rat muscularis externa organotypic cultures.ResultsThe expression of 13 miRNAs was increased in STC samples. Of those miRNAs, four were predicted to target SCN5A, the gene that encodes the Na+ channel NaV1.5. The expression of SCN5A mRNA was decreased in STC samples. Let-7f significantly decreased Na+ current density in vitro in human smooth muscle cells. In rat muscularis externa organotypic cultures, overexpression of let-7f resulted in reduced frequency and amplitude of contraction.ConclusionsA small group of miRNAs is upregulated in STC, and many of these miRNAs target the SCN5A-encoded Na+ channel NaV1.5. Within this set, a novel NaV1.5 regulator, let-7f, resulted in decreased NaV1.5 expression, current density and reduced motility of GI smooth muscle. These results suggest NaV1.5 and miRNAs as novel diagnostic and potential therapeutic targets in STC.

Characterization of motor patterns in isolated human colon: are there differences in patients with slow-transit constipation?

2012 ◽  
Vol 302 (1) ◽  
pp. G34-G43 ◽  
Author(s):  
Nick J. Spencer ◽  
Melinda Kyloh ◽  
David A. Wattchow ◽  
Anthony Thomas ◽  
Tiong Cheng Sia ◽  
...  
Keyword(s):  
Muscle Tension ◽  
Human Colon ◽  
Slow Transit Constipation ◽  
Organ Bath ◽  
Motor Patterns ◽  
Slow Transit ◽  
Descending Colon ◽  
Transit Constipation

The patterns of motor activity that exist in isolated full-length human colon have not been described. Our aim was to characterize the spontaneous motor patterns in isolated human colon and determine whether these patterns are different in whole colons obtained from patients with slow-transit constipation (STC). The entire colon (excluding the anus), was removed from patients with confirmed STC and mounted longitudinally in an organ bath ∼120 cm in length, containing oxygenated Krebs' solution at 36°C. Changes in circular muscle tension were recorded from multiple sites simultaneously along the length of colon, by use of isometric force transducers. Recordings from isolated colons from non-STC patients revealed cyclical colonic motor complexes (CMCs) in 11 of 17 colons, with a mean interval and half-duration of contractions of 4.0 ± 0.6 min and 51.5 ± 15 s, respectively. In the remaining six colons, spontaneous irregular phasic contractions occurred without CMCs. Interestingly, in STC patients robust CMCs were still recorded, although their CMC pacemaker frequencies were slower. Intraluminal balloon distension of the ascending or descending colon evoked an ascending excitatory reflex contraction, or evoked CMC, in 8 of 30 trials from non-STC (control) colons, but not from colons obtained from STC patients. In many control segments of descending colon, spontaneous CMCs consisted of simultaneous ascending excitatory and descending inhibitory phases. In summary, CMCs can be recorded from isolated human colon, in vitro, but their intrinsic pacemaker frequency is considerably faster in vitro compared with previous human recordings of CMCs in vivo. The observation that CMCs occur in whole colons removed from STC patients suggests that the intrinsic pacemaker mechanisms underlying their generation and propagation are preserved in vitro, despite impaired transit along these same regions in vivo.

966 High-Resolution Colonic Motility Recordings In Vivo Compared With Ex Vivo Recordings After Colectomy, in Patients With Slow Transit Constipation

2016 ◽  
Vol 150 (4) ◽  
pp. S193
Author(s):  
Philip Dinning ◽  
Tiong Cheng Sia ◽  
Reizal Rosli ◽  
Raghu Kumar ◽  
Lukasz Wiklendt ◽  
...  
Keyword(s):  
High Resolution ◽  
Ex Vivo ◽  
Colonic Motility ◽  
Slow Transit Constipation ◽  
Slow Transit ◽  
Transit Constipation

scholarly journals Inducible Prmt1 ablation in adult vascular smooth muscle leads to contractile dysfunction and aortic dissection

2021 ◽  
Author(s):  
Jung-Hoon Pyun ◽  
Byeong-Yun Ahn ◽  
Tuan Anh Vuong ◽  
Su Woo Kim ◽  
Yunju Jo ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Aortic Dissection ◽  
Vascular Smooth Muscle ◽  
Vascular Function ◽  
Ex Vivo ◽  
Elastic Fiber ◽  
Aortic Aneurysms ◽  
Aortic Dilation ◽  
Smooth Muscle Contractility

AbstractVascular smooth muscle cells (VSMCs) have remarkable plasticity in response to diverse environmental cues. Although these cells are versatile, chronic stress can trigger VSMC dysfunction, which ultimately leads to vascular diseases such as aortic aneurysm and atherosclerosis. Protein arginine methyltransferase 1 (Prmt1) is a major enzyme catalyzing asymmetric arginine dimethylation of proteins that are sources of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase. Although a potential role of Prmt1 in vascular pathogenesis has been proposed, its role in vascular function has yet to be clarified. Here, we investigated the role and underlying mechanism of Prmt1 in vascular smooth muscle contractility and function. The expression of PRMT1 and contractile-related genes was significantly decreased in the aortas of elderly humans and patients with aortic aneurysms. Mice with VSMC-specific Prmt1 ablation (smKO) exhibited partial lethality, low blood pressure and aortic dilation. The Prmt1-ablated aortas showed aortic dissection with elastic fiber degeneration and cell death. Ex vivo and in vitro analyses indicated that Prmt1 ablation significantly decreased the contractility of the aorta and traction forces of VSMCs. Prmt1 ablation downregulated the expression of contractile genes such as myocardin while upregulating the expression of synthetic genes, thus causing the contractile to synthetic phenotypic switch of VSMCs. In addition, mechanistic studies demonstrated that Prmt1 directly regulates myocardin gene activation by modulating epigenetic histone modifications in the myocardin promoter region. Thus, our study demonstrates that VSMC Prmt1 is essential for vascular homeostasis and that its ablation causes aortic dilation/dissection through impaired myocardin expression.

Smooth muscle inclusion bodies in slow transit constipation

2001 ◽  
Vol 193 (3) ◽  
pp. 390-397 ◽  
Author(s):  
Charles H. Knowles ◽  
Carole D. Nickols ◽  
S. Mark Scott ◽  
Nick I. Bennett ◽  
Ricardo Brandt de Oliveira ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Inclusion Bodies ◽  
Slow Transit Constipation ◽  
Slow Transit ◽  
Transit Constipation

scholarly journals Insights from a novel model of slow-transit constipation generated by partial outlet obstruction in the murine large intestine

2012 ◽  
Vol 303 (9) ◽  
pp. G1004-G1016 ◽  
Author(s):  
Dante J. Heredia ◽  
Nathan Grainger ◽  
Conor J. McCann ◽  
Terence K. Smith
Keyword(s):  
Outlet Obstruction ◽  
Circular Muscle ◽  
Slow Transit Constipation ◽  
Purse String ◽  
Slow Transit ◽  
Cox 2 ◽  
Transit Constipation ◽  
Novel Model

The mechanisms underlying slow-transit constipation (STC) are unclear. In 50% of patients with STC, some form of outlet obstruction has been reported; also an elongated colon has been linked to patients with STC. Our aims were 1) to develop a murine model of STC induced by partial outlet obstruction and 2) to determine whether this leads to colonic elongation and, consequently, activation of the inhibitory “occult reflex,” which may contribute to STC in humans. Using a purse-string suture, we physically reduced the maximal anal sphincter opening in C57BL/6 mice. After 4 days, the mice were euthanized (acutely obstructed), the suture was removed (relieved), or the suture was removed and replaced repeatedly (chronically obstructed, over 24–31 days). In partially obstructed mice, we observed increased cyclooxygenase (COX)-2 levels in muscularis and mucosa, an elongated impacted large bowel, slowed transit, nonpropagating colonic migrating motor complexes (CMMCs), a lack of mucosal reflexes, a depolarized circular muscle with slow-wave activity due to a lack of spontaneous inhibitory junction potentials, muscle hypertrophy, and CMMCs in mucosa-free preparations. Elongation of the empty obstructed colon produced a pronounced occult reflex. Removal of the obstruction or addition of a COX-2 antagonist (in vitro and in vivo) restored membrane potential, spontaneous inhibitory junction potentials, CMMC propagation, and mucosal reflexes. We conclude that partial outlet obstruction increases COX-2 leading to a hyperexcitable colon. This hyperexcitability is largely due to suppression of only descending inhibitory nerve pathways by prostaglandins. The upregulation of motility is suppressed by the occult reflex activated by colonic elongation.

scholarly journals Effect of atractylenolide III on interstitial cells of Cajal and C-kit/SCF pathway of rats with loperamide-induced slow transit constipation

2021 ◽  
Vol 18 (6) ◽  
pp. 1197-1204
Author(s):  
Wang Hao ◽  
Gong Yuxia ◽  
Li Youran ◽  
Xu Minmin ◽  
Gu Yunfe
Keyword(s):  
Smooth Muscle ◽  
Western Blot ◽  
Smooth Muscle Cells ◽  
Slow Transit Constipation ◽  
Model Group ◽  
Rt Pcr ◽  
Mucous Layer ◽  
Slow Transit ◽  
Transit Constipation ◽  
Atractylenolide Iii

Purpose: To determine the effect of atractylenolide-III (ATL-III) on loperamide-induced slow transit constipation (STC) in a rat STC model, and to elucidate the mechanisms involved. Methods: Male Wistar rats were divided into five groups (n=6 per group): normal control group (NG), model group, and three STC rat groups treated with different doses of ATL-III, viz, 5, 10 and 15 mg/kg. The rats were treated for 15 days. Feed consumption, fecal excretion and intestinal transit rate were determined. Nitric oxide synthase (NOS), somatostatin (SS), serotonin (5-HT), and vasoactive intestinal peptide (VIP) were measured with enzyme-linked immunosorbent assay (ELISA). The protein and mRNA expressions of C-kit, SCF, PKC, and PI-3K were assayed using Western blot analysis and realtime reverse transcription polymerase chain reaction (RT-PCR), respectively. Results: The amount, weight, and moisture content of stool, and water consumption were significantly higher in ATL-III-treated groups than in the untreated (model) group (p < 0.05), whereas no difference was observed in feed intake. Intestinal transit rate was higher in the ATL-III-treated groups (p < 0.05). Decreased NOS, SS and VIP levels and increased 5-HT level were seen in the ATL-III-treated groups (p < 0.05). ATL-III treatment also induced increases in smooth muscle cells, neuronal cells, and mucous layer (p<0.05). Results from RT-PCR and Western blot revealed that ATL-III–treated groups had elevated c-kit, SCF, PKC, as well as PI-3K mRNA and protein expressions (p < 0.05). Conclusion: These results suggest that ATL-III mitigates loperamide-induced STC in rats via stimulation of NOS, SS, VIP, and 5-HT secretions. It also increases smooth muscle cells, neuronal cells, and mucous layer, and regulates the signaling pathways involving PKC, PI3K, SCF, and c-kit.

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