Loss-of-function of b-catenin bar-1 slows development and activates the Wnt pathway in Caenorhabditis elegans
Bent, M.L. van der; Sterken, M.G. ; Volkers, J.M. ; Riksen, J.A.G. ; Schmid, T. ; Hajnal, A. ; Kammenga, J.E. ; Snoek, L.B. - \ 2014
Scientific Reports 4 (2014). - ISSN 2045-2322 - 7 p.
natural variation data - c-elegans - signaling components - neuroblast migration - negative regulator - vulval development - gene-expression - cell-migration - proteins - endoderm
C. elegans is extensively used to study the Wnt-pathway and most of the core-signalling components are known. Four beta-catenins are important gene expression regulators in Wnt-signalling. One of these, bar-1, is part of the canonical Wnt-pathway. Together with Wnt effector pop-1, bar-1 forms a transcription activation complex which regulates the transcription of downstream genes. The effects of bar-1 loss-of-function mutations on many phenotypes have been studied well. However, the effects on global gene expression are unknown. Here we report the effects of a loss-of-function mutation bar-1(ga80). By analysing the transcriptome and developmental phenotyping we show that bar-1(ga80) impairs developmental timing. This developmental difference confounds the comparison of the gene expression profile between the mutant and the reference strain. When corrected for this difference it was possible to identify genes that were directly affected by the bar-1 mutation. We show that the Wnt-pathway itself is activated, as well as transcription factors elt-3, pqm-1, mdl-1 and pha-4 and their associated genes. The outcomes imply that this response compensates for the loss of functional bar-1. Altogether we show that bar-1 loss-of function leads to delayed development possibly caused by an induction of a stress response, reflected by daf-16 activated genes.
New tools for studying osteoarthritis genetics in zebrafish
Mitchell, R.E. ; Huitema, L.F. ; Skinner, R.E. ; Brunt, L.H. ; Severn, C. ; Schulte-Merker, S. ; Hammond, C.L. - \ 2013
Osteoarthritis and Cartilage 21 (2013)2. - ISSN 1063-4584 - p. 269 - 278.
nucleotide exchange factor - danio-rerio - osteogenesis-imperfecta - developing skeleton - signaling pathways - cell-migration - bone-formation - retinoic acid - expression - gdf5
Objective: Increasing evidence points to a strong genetic component to osteoarthritis (OA) and that certain changes that occur in osteoarthritic cartilage recapitulate the developmental process of endochondral ossification. As zebrafish are a well validated model for genetic studies and developmental biology, our objective was to establish the spatiotemporal expression pattern of a number of OA susceptibility genes in the larval zebrafish providing a platform for functional studies into the role of these genes in OA. Design: We identified the zebrafish homologues for Mcf2l, Gdf5, PthrP/Pthlh, Co19a2, and Col10a1 from the Ensembl genome browser. Labelled probes were generated for these genes and in situ hybridisations were performed on wild type zebrafish larvae. In addition, we generated transgenic reporter lines by modification of bacterial artificial chromosomes (BACs) containing full length promoters for col2a1 and col10a1. Results: For the first time, we show the spatiotemporal expression pattern of Mcf2l. Furthermore, we show that all six putative OA genes are dynamically expressed during zebrafish larval development, and that all are expressed in the developing skeletal system. Furthermore, we demonstrate that the transgenic reporters we have generated for col2a1 and col10al can be used to visualise chondrocyte hypertrophy in vivo. Conclusion: In this study we describe the expression pattern of six OA susceptibility genes in zebrafish larvae and the generation of two new transgenic lines marking chondrocytes at different stages of maturation. Moreover, the tools used demonstrate the utility of the zebrafish model for functional studies on genes identified as playing a role in OA. (C) 2012 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.
Angiopoietin-Like 4 Interacts with Integrins ß1 and ß5 to Modulate Keratinocyte Migration
Goh, Y.Y. ; Pal, M. ; Chong, H.C. ; Zhu, P. ; Tan, M.J. ; Punugu, L. ; Lam, C.R.I. ; Yau, Y.H. ; Tan, C.K. ; Huang, R.L. ; Tan, S. ; Yang Tang, M.B. ; Ling Ding, J. ; Kersten, A.H. ; Tan, N.S. - \ 2010
American Journal of Pathology 177 (2010)6. - ISSN 0002-9440 - p. 2791 - 2803.
induced adipose factor - cell-migration - alpha-6-beta-4 integrin - in-vivo - protein - kinase - expression - repair - metastasis - inhibition
Adipose tissue secretes adipocytokines for energy homeostasis, but recent evidence indicates that some adipocytokines also have a profound local impact on wound healing. Upon skin injury, keratinocytes use various signaling molecules to promote reepithelialization for efficient wound closure. In this study, we identify a novel function of adipocytokine angiopoietin-like 4 (ANGPTL4) in keratinocytes during wound healing through the control of both integrin-mediated signaling and internalization. Using two different in vivo models based on topical immuno-neutralization of ANGPTL4 as well as ablation of the ANGPTL4 gene, we show that ANGPTL4-deficient mice exhibit delayed wound reepithelialization with impaired keratinocyte migration. Human keratinocytes in which endogenous ANGPTL4 expression was suppressed by either siRNA or a neutralizing antibody show impaired migration associated with diminished integrin-mediated signaling. Importantly, we identify integrins ß1 and ß5, but not ß3, as novel binding partners of ANGPTL4. ANGPTL4-bound integrin ß1 activated the FAK-Src-PAK1 signaling pathway, which is important for cell migration. The findings presented herein reveal an unpredicted role of ANGPTL4 during wound healing and demonstrate how ANGPTL4 stimulates intracellular signaling mechanisms to coordinate cellular behavior. Our findings provide insight into a novel cell migration control mechanism and underscore the physiological importance of the modulation of integrin activity in cancer metastasis