Search

Epithelial integrity is lost upon cancer progression as cancer cells detach from the primary tumor site and start to invade to the surrounding tissues. Invasive cancers of epithelial origin often express altered levels of TRP-family cation channels. Upregulation of TRPV6 Ca2+-channel has been associated with a number of human malignancies and its high expression in breast cancer has been linked to both proliferation and invasive disease. The mechanisms behind the potential of TRPV6 to induce invasive progression have, however, not been well elucidated. Here we show that TRPV6 is connected to both E-cadherin-based adherens junctions and intracellular cytoskeletal structures. Loss of TRPV6 from normal mammary epithelial cells led to disruption of epithelial integrity and abnormal 3D-mammo sphere morphology. Furthermore, expression level of TRPV6 was tightly linked to the levels of common EMT markers, suggesting that TRPV6 may have a role in the mesenchymal invasion of breast cancer cells. Thus, either too low or too high TRPV6 levels compromise homeostasis of the mammary epithelial sheets and may promote the progression of pathophysiological conditions.

International audience; At mitosis onset, cortical tension increases and cells round up, ensuring correct spindle morphogenesis and orientation. Thus, cortical tension sets up the geometric requirements of cell division. On the contrary, cortical tension decreases during meiotic divisions in mouse oocytes, a puzzling observation because oocytes are round cells, stable in shape, that actively position their spindles. We investigated the pathway leading to reduction in cortical tension and its significance for spindle positioning. We document a previously uncharacterized Arp2/3-dependent thickening of the cortical F-actin essential for first meiotic spindle migration to the cortex. Using micropipette aspiration, we show that cortical tension decreases during meiosis I, resulting from myosin-II exclusion from the cortex, and that cortical F-actin thickening promotes cortical plasticity. These events soften and relax the cortex. They are triggered by the Mos–MAPK pathway and coordinated temporally. Artificial cortex stiffening and theoretical modelling demonstrate that a soft cortex is essential for meiotic spindle positioning.

Objectives Alverine, an antispasmodic agent for the treatment of irritable bowel syndrome (IBS), may be combined with simethicone, a protective agent of the mucosa. Stress is a major factor triggering abdominal pain in IBS and causing hypersensitivity to colonic distension in animals through an increased colonic permeability. The antinociceptive effects of alverine and simethicone, separately or in association, were evaluated on stress-induced colonic hypersensitivity to distension in rats. The influence of simethicone on altered permeability was also tested. Methods Groups of 8–10 female adult Wistar rats (200–250 g) housed individually were used. Gut paracellular permeability was evaluated after 2 h of partial restraint stress using oral gavage with 51Cr-EDTA and 24 h of urine collection. The number of abdominal cramps during colonic distension was evaluated in animals equipped with electrodes on their abdominal striated muscles. Key Findings At 200 mg/kg p.o. twice a day, but not at lower doses, simethicone reduced stress-induced increase of colonic permeability and hypersensitivity to distension. Administered alone at 10 mg/kg p.o., alverine also reduced stress-induced hypersensitivity to distension; lower doses were inactive. However, alverine administered at an inactive dose with simethicone suppressed stress-induced hypersensitivity to distension. Conclusions We conclude that both simethicone and alverine have visceral antinociceptive effects by two different mechanisms and that simethicone exerts a potentiating effect on the antinociceptive action of alverine.

International audience; Background and aims: Intestinal barrier impairment is incriminated in the pathophysiology of intestinal gut disorders associated with psychiatric comorbidity. Increased intestinal permeability associated with upload of lipopolysaccharides (LPS) translocation induces depressive symptoms. Gut microbiota and probiotics alter behavior and brain neurochemistry. Since Lactobacillus farciminis suppresses stress-induced hyperpermeability, we examined whether (i) L. farciminis affects the HPA axis stress response, (ii) stress induces changes in LPS translocation and central cytokine expression which may be reversed by L. farciminis, (iii) the prevention of "leaky" gut and LPS upload are involved in these effects. Methods: At the end of the following treatments female rats were submitted to a partial restraint stress (PRS) or sham-PRS: (i) oral administration of L. farciminis during 2 weeks, (ii) intraperitoneat administration of ML-7 (a specific myosin light chain kinase inhibitor), (iii) antibiotic administration in drinking water during 12 days. After PRS or sham-PRS session, we evaluated LPS levels in portal blood, plasma corticosterone and adrenocorticotropic hormone (ACTH) levels, hypothalamic corticotropin releasing factor (CRF) and pro-inflammatory cytokine mRNA expression, and colonic paracellular permeability (CPP). Results: PRS increased plasma ACTH and corticosterone; hypothalamic CRF and pro-inflammatory cytokine expression; CPP and portal blood concentration of LPS. L. farciminis and ML-7 suppressed stress-induced hyperpermeability, endotoxemia and prevented HPA axis stress response and neuroinflammation. Antibiotic reduction of luminal LPS concentration prevented HPA axis stress response and increased hypothalamic expression of pro-inflammatory cytokines. Conclusion: The attenuation of the HPA axis response to stress by L. farciminis depends upon the prevention of intestinal barrier impairment and decrease of circulating LPS levels. (c) 2012 Elsevier Ltd. All rights reserved.

Dysfunctional regulation of airway smooth muscle tone is a feature of obstructive airway diseases such as asthma and chronic obstructive pulmonary disease. Airway smooth muscle contraction is directly associated with changes in the phosphorylation of myosin light chain (MLC), which is increased by Rho and decreased by Rac. Although cyclic adenosine monophosphate (cAMP)-elevating agents are believed to relieve bronchoconstriction mainly via activation of protein kinase A (PKA), here we addressed the role of the novel cAMP-mediated exchange protein Epac in the regulation of airway smooth muscle tone. Isometric tension measurements showed that specific activation of Epac led to relaxation of guinea pig tracheal preparations pre-contracted with methacholine, independently of PKA. In airway smooth muscle cells, Epac activation reduced methacholine-induced MLC phosphorylation. Moreover, when Epac was stimulated, we observed a decreased methacholine-induced RhoA activation, measured by both stress fibre formation and pull-down assay whereas the same Epac activation prevented methacholine-induced Rac1 inhibition measured by pull-down assay. Epac-driven inhibition of both methacholine-induced muscle contraction by Toxin B-1470, and MLC phosphorylation by the Rac1-inhibitor NSC23766, were significantly attenuated, confirming the importance of Rac1 in Epac-mediated relaxation. Importantly, human airway smooth muscle tissue also expresses Epac, and Epac activation both relaxed pre-contracted human tracheal preparations and decreased MLC phosphorylation. Collectively, we show that activation of Epac relaxes airway smooth muscle by decreasing MLC phosphorylation by skewing the balance of RhoA/Rac1 activation towards Rac1. Therefore, activation of Epac may have therapeutical potential in the treatment of obstructive airway diseases.

Gene-gene interactions are proposed as an important component of the genetic architecture of complex diseases, and are just beginning to be evaluated in the context of genome-wide association studies (GWAS). In addition to detecting epistasis, a benefit to interaction analysis is that it also increases power to detect weak main effects. We conducted a knowledge-driven interaction analysis of a GWAS of 931 multiple sclerosis (MS) trios to discover gene-gene interactions within established biological contexts. We identify heterogeneous signals, including a gene-gene interaction between CHRM3 (muscarinic cholinergic receptor 3) and MYLK (myosin light-chain kinase) (joint P=0.0002), an interaction between two phospholipase C-β isoforms, PLCβ1 and PLCβ4 (joint P=0.0098), and a modest interaction between ACTN1 (actinin alpha 1) and MYH9 (myosin heavy chain 9) (joint P=0.0326), all localized to calcium-signaled cytoskeletal regulation. Furthermore, we discover a main effect (joint P=5.2E-5) previously unidentified by single-locus analysis within another related gene, SCIN (scinderin), a calcium-binding cytoskeleton regulatory protein. This work illustrates that knowledge-driven interaction analysis of GWAS data is a feasible approach to identify new genetic effects. The results of this study are among the first gene-gene interactions and non-immune susceptibility loci for MS. Further, the implicated genes cluster within inter-related biological mechanisms that suggest a neurodegenerative component to MS.

Vasopressin and its receptors modulate several gut functions, but their role in intestinal inflammation is unknown. Our aims were to determine 1) the localization of V1b receptors in human and rodent colon, 2) the role of vasopressin and V1b receptors in experimental colitis using two approaches: V1b−/− mice and a selective V1b receptor antagonist, SSR149415, and 3) the mechanisms involved. V1b receptors were localized in normal and inflamed colon from humans and rats. Experimental colitis was induced in rats and mice and some groups were treated before or after colitis induction with oral SSR149415 (3–30 mg/kg). Other groups of mice were submitted to dehydration to increase vasopressin plasma levels, prior to colitis induction. Body weight, damage scores, MPO, and TNF-α tissue levels were determined. Finally, colonic segments of wild-type (WT) and V1b−/− mice were mounted in Ussing chambers and paracellular permeability in response to vasopressin was studied. V1b receptors were expressed in enterocytes and ganglia cells of the enteric nervous system of human and rat intestine. Expression levels were independent from inflammatory status. Colitis was less severe in rodents treated by either preventive or curative SSR149415 and in V1b−/− mice. 2,4,6-Trinitrobenzene sulfonic acid induced a strong mortality in dehydrated animals that was reversed by preventive SSR149415 or mast cell stabilizer. Vasopressin significantly increased paracellular permeability in WT, but not in V1b−/− mice. Preincubation of colon tissues with SSR149415 abolished the vasopressin effect. Similarly, vasopressin had no effect in colonic preparations from WT mice pretreated with mast cell stabilizers. Vasopressin, through V1b receptor interaction, has proinflammatory properties linked to mast cell activation and downstream alterations of the colonic epithelial barrier. These findings underline the potential interest of V1b receptor blockers in gut inflammatory diseases.