Dataset Information

?3 integrin-mediated spreading induced by matrix-bound BMP-2 controls Smad signaling in a stiffness-independent manner.

ABSTRACT: Understanding how cells integrate multiple signaling pathways to achieve specific cell differentiation is a challenging question in cell biology. We have explored the physiological presentation of BMP-2 by using a biomaterial that harbors tunable mechanical properties to promote localized BMP-2 signaling. We show that matrix-bound BMP-2 is sufficient to induce ?3 integrin-dependent C2C12 cell spreading by overriding the soft signal of the biomaterial and impacting actin organization and adhesion site dynamics. In turn, ?v?3 integrin is required to mediate BMP-2-induced Smad signaling through a Cdc42-Src-FAK-ILK pathway. ?3 integrin regulates a multistep process to control first BMP-2 receptor activity and second the inhibitory role of GSK3 on Smad signaling. Overall, our results show that BMP receptors and ?3 integrin work together to control Smad signaling and tensional homeostasis, thereby coupling cell adhesion and fate commitment, two fundamental aspects of developmental biology and regenerative medicine.

SUBMITTER: Fourel L

PROVIDER: S-EPMC4792076 | biostudies-literature | 2016 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

β3 integrin-mediated spreading induced by matrix-bound BMP-2 controls Smad signaling in a stiffness-independent manner.

Fourel Laure L Valat Anne A Faurobert Eva E Guillot Raphael R Bourrin-Reynard Ingrid I Ren Kefeng K Lafanechère Laurence L Planus Emmanuelle E Picart Catherine C Albiges-Rizo Corinne C

The Journal of cell biology 20160307 6

Understanding how cells integrate multiple signaling pathways to achieve specific cell differentiation is a challenging question in cell biology. We have explored the physiological presentation of BMP-2 by using a biomaterial that harbors tunable mechanical properties to promote localized BMP-2 signaling. We show that matrix-bound BMP-2 is sufficient to induce β3 integrin-dependent C2C12 cell spreading by overriding the soft signal of the biomaterial and impacting actin organization and adhesion ...[more]

PMID: 26953352

Similar Datasets

Project description:Surface coatings delivering BMP are a promising approach to render biomaterials osteoinductive. In contrast to soluble BMPs which can interact with their receptors at the dorsal side of the cell, BMPs presented as an insoluble cue physically bound to a biomimetic matrix, called here matrix-bound (bBMP-2), are presented to cells by their ventral side. To date, BMP-2 internalization and signaling studies in cell biology have always been performed by adding soluble (sBMP-2) to cells adhered on cell culture plates or glass slides, which will be considered here as a "reference" condition. However, whether and how matrix-bound BMP-2 can be internalized by cells and its relation to canonical (SMAD) and non-canonical signaling (ALP) remain open questions. In this study, we investigated the uptake and processing of BMP-2 by C2C12 myoblasts. This BMP-2 was presented either embedded in polyelectrolyte multilayer films (matrix-bound presentation) or as soluble form. Using fluorescently labeled BMP-2, we showed that the amount of matrix-bound BMP-2 internalized is dependent on the level of crosslinking of the polyelectrolyte films. Cav-1-mediated internalization is related to both SMAD and ALP signaling, while clathrin-mediated is only related to ALP signaling. BMP-2 internalization was independent of the presentation mode (sBMP-2 versus bBMP-2) for low crosslinked films (soft, EDC10) in striking contrast with high crosslinked (stiff, EDC70) films where internalization was much lower and slower for bBMP-2. As anticipated, internalization of sBMP-2 barely depended on the underlying matrix. Taken together, these results indicate that BMP-2 internalization can be tuned by the underlying matrix and activates downstream BMP-2 signaling, which is key for the effective formation of bone tissue. STATEMENT OF SIGNIFICANCE:The presentation of growth factors from material surfaces currently presents significant challenges in academic research, clinics and industry. Being able to deliver efficiently these growth factors by a biomaterial will open new perspectives for regenerative medicine. However, to date, very little is known about how matrix-bound growth factors are delivered to cells, especially whether they are internalized and how they are signaling to drive key differentiation events. These initial steps are crucial as they will guide the subsequent processes leading to tissue regeneration. In this work, we investigate the uptake and processing by cells of BMP-2 ligands embedded in polyelectrolyte multilayer films in comparison to soluble BMP-2. We show that BMP-2 responsive cells can internalize matrix-bound BMP-2 and that internalization is dependent on the cross-linking level of the polyelectrolyte films. In addition, we show that internalization is mediated by both clathrin- and caveolin-dependent pathways. While inhibiting clathrin-dependent endocytosis affects only non-canonical signaling, blocking caveolin-1-dependent endocytosis reduces both canonical and non-canonical BMP signaling. The signaling pathways found for matrix-bound BMP-2 are similar to those found for soluble BMP-2. These results highlight that BMP-2 presented by a biomaterial at the ventral side of the cell can trigger major endocytic and associated signaling pathways leading to bone regeneration.

Project description:BACKGROUND:Human mesenchymal stem cell (hMSC) differentiation into osteoblasts has important clinical significance in treating bone injury, and the stiffness of the extracellular matrix (ECM) has been shown to be an important regulatory factor for hMSC differentiation. The aim of this study was to further delineate how matrix stiffness affects intracellular signaling through integrin ?5/?1, FAK, and Wnt signaling, subsequently regulating the osteogenic phenotype of hMSCs. METHODS:hMSCs were cultured on tunable polyacrylamide hydrogels coated with fibronectin with stiffness corresponding to a Young's modulus of 13-16 kPa and 62-68 kPa. After hMSCs were cultured on gels for 1 week, gene expression of alpha-1 type I collagen, BGLAP, and RUNX2 were evaluated by real-time PCR. After hMSCs were cultured on gels for 24 h, signaling molecules relating to integrin ?5 (FAK, ERK, p-ERK, Akt, p-Akt, GSK-3?, p-GSK-3?, and ?-catenin) were evaluated by western blot analysis. RESULTS:Osteogenic differentiation was increased on 62-68 kPa ECM, as evidenced by alpha-1 type I collagen, BGLAP, and RUNX2 gene expression, calcium deposition, and ALP staining. In the process of differentiation, gene and protein expression of integrin ?5/?1 increased, together with protein expression of the downstream signaling molecules FAK, p-ERK, p-Akt, GSK-3?, p-GSK-3?, and ?-catenin, indicating that these molecules can affect the osteogenic differentiation of hMSCs. An antibody blocking integrin ?5 suppressed the stiffness-induced expression of all osteoblast markers examined. In particular, alpha-1 type I collagen, RUNX2, and BGLAP were significantly downregulated, indicating that integrin ?5 regulates hMSC osteogenic differentiation. Downstream expression of FAK, ERK, p-ERK, and ?-catenin protein was unchanged, whereas Akt, p-Akt, GSK-3?, and p-GSK-3? were upregulated. Moreover, expression of Akt and p-Akt was upregulated with anti-integrin ?5 antibody, but no difference was observed for FAK, ERK, and p-ERK between the with or without anti-integrin ?5 antibody groups. At the same time, expression of GSK-3? and p-GSK-3? was upregulated and ?-catenin levels showed no difference between the groups with or without anti-integrin ?5 antibody. Since Akt, p-Akt, GSK-3?, and p-GSK-3? displayed the same changes between the groups with or without anti-integrin ?5 antibody, we then detected the links among them. Expression of p-Akt and p-GSK-3? was reduced effectively in the presence of the Akt inhibitor Triciribine. However, Akt, GSK-3?, and ?-catenin were unchanged. These results suggested that expression of p-GSK-3? was regulated by p-Akt on 62-68 kPa ECM. CONCLUSIONS:Taken together, our results provide evidence that matrix stiffness (62-68 kPa) affects the osteogenic outcome of hMSCs through mechanotransduction events that are mediated by integrin ?5.

Dataset Information

?3 integrin-mediated spreading induced by matrix-bound BMP-2 controls Smad signaling in a stiffness-independent manner.

Publications

β3 integrin-mediated spreading induced by matrix-bound BMP-2 controls Smad signaling in a stiffness-independent manner.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets