Jun kinase-induced overexpression of leukemia-associated Rho GEF (LARG) mediates sustained hypercontraction of longitudinal smooth muscle in inflammation

Abstract

Al-Shboul O, Nalli AD, Kumar DP, Zhou R, Mahavadi S, Kuemmerle JF, Grider JR, Murthy KS. Jun kinase-induced overexpression of leukemia-associated Rho GEF (LARG) mediates sustained hypercontraction of longitudinal smooth muscle in inflammation. Am J Physiol Cell Physiol 306: C1129 -C1141, 2014. First published April 16, 2014; doi:10.1152/ajpcell.00021.2014.-The signaling pathways mediating sustained contraction of mouse colonic longitudinal smooth muscle and the mechanisms involved in hypercontractility of this muscle layer in response to cytokines and TNBS-induced colitis have not been fully explored. In control longitudinal smooth muscle cells, ACh acting via m3 receptors activated sequentially G␣12, RhoGEF (LARG), and the RhoA/Rho kinase pathway. There was abundant expression of MYPT1, minimal expression of CPI-17, and a notable absence of a PKC/CPI-17 pathway. LARG expression was increased in longitudinal muscle cells isolated from muscle strips cultured for 24 h with IL-1␤ or TNF-␣ or obtained from the colon of TNBS-treated mice. The increase in LARG expression was accompanied by a significant increase in ACh-stimulated Rho kinase and ZIP kinase activities, and sustained muscle contraction. The increase in LARG expression, Rho kinase and ZIP kinase activities, and sustained muscle contraction was abolished in cells pretreated with the Jun kinase inhibitor, SP600125. Expression of the MLCP activator, telokin, and MLCP activity were also decreased in longitudinal muscle cells from TNBS-treated mice or from strips treated with IL-1␤ or TNF-␣. In contrast, previous studies had shown that sustained contraction in circular smooth muscle is mediated by sequential activation of G␣13, p115RhoGEF, and dual RhoA-dependent pathways involving phosphorylation of MYPT1 and CPI-17. In colonic circular smooth muscle cells isolated from TNBS-treated mice or from strips treated with IL-1␤ or TNF-␣, CPI-17 expression and sustained muscle contraction were decreased. The disparate changes in the two muscle layers contribute to intestinal dysmotility during inflammation.colon; contraction; cytokines; signaling GASTROINTESTINAL smooth muscle exhibits regional variations in expression of structural, contractile, and signaling proteins that can influence its response to a variety of regulatory agents (e.g., acetylcholine, biogenic amines, neuropeptides, pyrimidines/purines; lipids, and cytokines) (3,12,27,37,57). Functional differences are evident between muscle layers (e.g., circular vs. longitudinal muscle of the intestine) or within the same layer (proximal tonic vs. distal rhythmic circular muscle of the stomach) (10,19,31,35,38,58,59). In all types of smooth muscle, an essential requirement for contraction is phosphorylation of the 20-kDa regulatory light chain (MLC) of myosin II (MLC 20 ), which in turn is regulated by the balance between Ca 2ϩ -dependent or -independent MLC kinase (MLCK) activity and MLC phosphatase (MLCP) activity (8,13,25,37,55).In both circular and longitudinal intestinal smooth muscle, contraction in respo...

Inhibition of smooth muscle contraction and ARF6 activity by the inhibitor for cytohesin GEFs, secinH3, in the human prostate

“…For RhoA or Rac, several other groups of GEFs have been proposed to mediate their activation in different cell types (5,38,41,67). PDZ-RhoGEF, leukemia-associated RhoGEF (LARG), Rho guanine nucleotide exchange factor 1 (Arhgef1), and p63RhoGEF have been demonstrated to mediate receptor-induced RhoA activation in smooth muscle contraction, which was mostly (though not exclusively) investigated in vascular smooth muscle (1,4,9,12,28,43,44). Kalirin, Vav2, and Trio were identified as Rac-activating GEFs in cultured smooth muscle cells (16,21,52,65).…”

Stimulation of synthesis and release of brain‐derived neurotropic factor from intestinal smooth muscle cells by substance P and pituitary adenylate cyclase‐activating peptide

“…Thus, BDNF acts in an autocrine manner leading to hypercontractility of the longitudinal muscle of the intestine. Considering that SP and BDNF are increased in intestinal inflammation it is possible that this autocrine loop leads to the hypercontractility that is characteristic of the response of longitudinal smooth muscle in inflammatory bowel disease …”

“…Considering that SP and BDNF are increased in intestinal inflammation it is possible that this autocrine loop leads to the hypercontractility that is characteristic of the response of longitudinal smooth muscle in inflammatory bowel disease. 60…”

Cytokine-Induced S-Nitrosylation of Soluble Guanylyl Cyclase and Expression of Phosphodiesterase 1A Contribute to Dysfunction of Longitudinal Smooth Muscle Relaxation

“…Colonic inflammation in mice was induced with TNBS as described previously (Hazelgrove et al, 2009;Alkahtani et al, 2013;Al-Shboul et al, 2014;Mahavadi et al, 2014;Nalli et al, 2014). Adult male mice (C57BL/6J; 6-8 weeks old) were anesthetized, and 100 ml of TNBS [2.5% in 50% ethanol (v/v)] was instilled intrarectally; mice were euthanized 3 days after the induction of inflammation.…”

“…Body weight and stool consistency were evaluated daily. Colonic tissue from mice treated with TNBS exhibited typical histologic characteristics of colitis (Alkahtani et al, 2013;Al-Shboul et al, 2014;Mahavadi et al, 2014;Nalli et al, 2014). Distal colonic segments 2-3 cm long were obtained from control and TNBS-treated mice, and muscle cells from the longitudinal muscle layer were obtained as described previously (Murthy et al, 2002(Murthy et al, , 2003Mahavadi et al, 2013Mahavadi et al, , 2014.…”