Showing papers by "Andras Kapus published in 2016"

Context-dependent switch in chemo/mechanotransduction via multilevel crosstalk among cytoskeleton-regulated MRTF and TAZ and TGFβ-regulated Smad3.

Abstract: Myocardin-related transcription factor (MRTF) and TAZ are major mechanosensitive transcriptional co-activators that link cytoskeleton organization to gene expression. Despite many similarities in their regulation, their physical and/or functional interactions are unknown. Here we show that MRTF and TAZ associate partly through a WW domain-dependent mechanism, and exhibit multilevel crosstalk affecting each other’s expression, transport and transcriptional activity. Specifically, MRTF is essential for TAZ expression; TAZ and MRTF inhibit each other’s cytosolic mobility and stimulus-induced nuclear accumulation; they antagonize each other’s stimulatory effect on the α-smooth muscle actin (SMA) promoter, which harbours nearby cis-elements for both, but synergize on isolated TEAD-elements. Importantly, TAZ confers Smad3 sensitivity to the SMA promoter. Thus, TAZ is a context-dependent switch during mechanical versus mechano/chemical signalling, which inhibits stretch-induced but is indispensable for stretch+TGFβ-induced SMA expression. Crosstalk between these cytoskeleton-regulated factors seems critical for fine-tuning mechanical and mechanochemical transcriptional programmes underlying myofibroblast transition, wound healing and fibrogenesis. MRTF and TAZ are mechanosensitive transcriptional coactivators, but how they functionally interact is not clear. Here the authors show that MRFT and TAZ exhibit multilevel crosstalk in expression, transport and transcriptional activity; furthermore, TAZ confers sensitivity to TGFβ activation of the smooth muscle actin promoter.

Role of Transient Receptor Potential Vanilloid 4 in Neutrophil Activation and Acute Lung Injury

Abstract: The cation channel transient receptor potential vanilloid (TRPV) 4 is expressed in endothelial and immune cells; however, its role in acute lung injury (ALI) is unclear. The functional relevance of TRPV4 was assessed in vivo, in isolated murine lungs, and in isolated neutrophils. Genetic deficiency of TRPV4 attenuated the functional, histological, and inflammatory hallmarks of acid-induced ALI. Similar protection was obtained with prophylactic administration of the TRPV4 inhibitor, GSK2193874; however, therapeutic administration of the TRPV4 inhibitor, HC-067047, after ALI induction had no beneficial effect. In isolated lungs, platelet-activating factor (PAF) increased vascular permeability in lungs perfused with trpv4(+/+) more than with trpv4(-/-) blood, independent of lung genotype, suggesting a contribution of TRPV4 on blood cells to lung vascular barrier failure. In neutrophils, TRPV4 inhibition or deficiency attenuated the PAF-induced increase in intracellular calcium. PAF induced formation of epoxyeicosatrienoic acids by neutrophils, which, in turn, stimulated TRPV4-dependent Ca(2+) signaling, whereas inhibition of epoxyeicosatrienoic acid formation inhibited the Ca(2+) response to PAF. TRPV4 deficiency prevented neutrophil responses to proinflammatory stimuli, including the formation of reactive oxygen species, neutrophil adhesion, and chemotaxis, putatively due to reduced activation of Rac. In chimeric mice, however, the majority of protective effects in acid-induced ALI were attributable to genetic deficiency of TRPV4 in parenchymal tissue, whereas TRPV4 deficiency in circulating blood cells primarily reduced lung myeloperoxidase activity. Our findings identify TRPV4 as novel regulator of neutrophil activation and suggest contributions of both parenchymal and neutrophilic TRPV4 in the pathophysiology of ALI.

The α11 integrin mediates fibroblast-extracellular matrix-cardiomyocyte interactions in health and disease.

Abstract: We demonstrate that the α11β1 (α11) integrin is critical for ECM accumulation in response to diabetes in vivo. Furthermore, we show that deletion of the fibroblast-specific α11 integrin disrupts no...

Research projects in the Surgeon-Scientist and Clinician-Investigator programs at the University of Toronto (1987-2016): a cohort study

Abstract: BACKGROUND Physicians have traditionally been at the forefront of medical research, bringing clinical questions to the laboratory and returning with ideas for treatment. However, we have anecdotally observed a decline in the popularity of basic science research among trainees. We hypothesized that fewer resident physicians have been pursuing basic science research training over time. METHODS We examined records from residents in the Surgeon-Scientist and Clinician-Investigator programs at the University of Toronto (1987-2016). Research by residents was categorized independently by 2 raters as basic science, clinical epidemiology or education-related based on the title of the project, the name of the supervisor and Pubmed searches. The study population was divided into quintiles of time, and the proportion pursuing basic science training in each quintile was calculated. RESULTS Agreement between the raters was 100%; the categorization of the research topic remained unclear in 9 cases. The proportion of trainees pursuing basic science training dropped by 60% from 1987 to 2016 (p = 0.005). INTERPRETATION Significantly fewer residents in the Surgeon-Scientist and Clinician-Investigator Programs at the University of Toronto are pursuing training in the basic sciences as compared with previous years.

Stimulus-dependent dissociation between XB130 and Tks5 scaffold proteins promotes airway epithelial cell migration

Abstract: // Serisha Moodley 1,2 , Mathieu Derouet 2 , Xiao Hui Bai 2 , Feng Xu 3 , Andras Kapus 1,4 , Burton B. Yang 1,5 and Mingyao Liu 1,2 1 Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Canada 2 Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute, University Health Network, Toronto, Canada 3 Advanced Optical Microscopy Facility, UHN, Toronto, Canada 4 Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Canada 5 Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Canada Correspondence to: Mingyao Liu, email: // Keywords : actin filament associate protein 1-like 2, SH3PXD2A, lamellipodia, podosomes, lung repair, Pathology Section Received : August 26, 2016 Accepted : November 02, 2016 Published : November 09, 2016 Abstract Repair of airway epithelium after injury requires migration of neighboring epithelial cells to injured areas. However, the molecular mechanisms regulating airway epithelial cell migration is not well defined. We have previously shown that XB130, a scaffold protein, is required for airway epithelial repair and regeneration in vivo , and interaction between XB130 and another scaffold protein, Tks5, regulates cell proliferation and survival in human bronchial epithelial cells. The objective of the present study was to determine the role of XB130 and Tks5 interaction in airway epithelial cell migration. Interestingly, we found that XB130 only promotes lateral cell migration, whereas, Tks5 promotes cell migration/invasion via proteolysis of extracellular matrix. Upon stimulation with EGF, PKC activator phorbol 12, 13-dibutyrate or a nicotinic acetylcholine receptor ligand, XB130 and Tks5 translocated to the cell membrane in a stimulus-dependent manner. The translocation and distribution of XB130 is similar to lamellipodial marker, WAVE2; whereas Tks5 is similar to podosome marker, N-WASP. Over-expression of XB130 or Tks5 alone enhances cell migration, whereas co-expression of both XB130 and Tks5 inhibits cell migration processes and signaling. Furthermore, XB130 interacts with Rac1 whereas Tks5 interacts with Cdc42 to promote Rho GTPase activity. Our results suggest that dissociation between XB130 and Tks5 may facilitate lateral cell migration via XB130/Rac1, and vertical cell migration via Tks5/Cdc42. These molecular mechanisms will help our understanding of airway epithelial repair and regeneration.