Dataset Information

SMAD3 and SMAD4 have a more dominant role than SMAD2 in TGFβ-induced chondrogenic differentiation of bone marrow-derived mesenchymal stem cells.

ABSTRACT: To improve cartilage formation by bone marrow-derived mesenchymal stem cells (BMSCs), the signaling mechanism governing chondrogenic differentiation requires better understanding. We previously showed that the transforming growth factor-β (TGFβ) receptor ALK5 is crucial for chondrogenesis induced by TGFβ. ALK5 phosphorylates SMAD2 and SMAD3 proteins, which then form complexes with SMAD4 to regulate gene transcription. By modulating the expression of SMAD2, SMAD3 and SMAD4 in human BMSCs, we investigated their role in TGFβ-induced chondrogenesis. Activation of TGFβ signaling, represented by SMAD2 phosphorylation, was decreased by SMAD2 knockdown and highly increased by SMAD2 overexpression. Moreover, TGFβ signaling via the alternative SMAD1/5/9 pathway was strongly decreased by SMAD4 knockdown. TGFβ-induced chondrogenesis of human BMSCs was strongly inhibited by SMAD4 knockdown and only mildly inhibited by SMAD2 knockdown. Remarkably, both knockdown and overexpression of SMAD3 blocked chondrogenic differentiation. Chondrogenesis appears to rely on a delicate balance in the amount of SMAD3 and SMAD4 as it was not enhanced by SMAD4 overexpression and was inhibited by SMAD3 overexpression. Furthermore, this study reveals that TGFβ-activated phosphorylation of SMAD2 and SMAD1/5/9 depends on the abundance of SMAD4. Overall, our findings suggest a more dominant role for SMAD3 and SMAD4 than SMAD2 in TGFβ-induced chondrogenesis of human BMSCs.

SUBMITTER: de Kroon LM

PROVIDER: S-EPMC5327413 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

SMAD3 and SMAD4 have a more dominant role than SMAD2 in TGFβ-induced chondrogenic differentiation of bone marrow-derived mesenchymal stem cells.

de Kroon Laurie M G LM Narcisi Roberto R van den Akker Guus G H GG Vitters Elly L EL Blaney Davidson Esmeralda N EN van Osch Gerjo J V M GJ van der Kraan Peter M PM

Scientific reports 20170227

To improve cartilage formation by bone marrow-derived mesenchymal stem cells (BMSCs), the signaling mechanism governing chondrogenic differentiation requires better understanding. We previously showed that the transforming growth factor-β (TGFβ) receptor ALK5 is crucial for chondrogenesis induced by TGFβ. ALK5 phosphorylates SMAD2 and SMAD3 proteins, which then form complexes with SMAD4 to regulate gene transcription. By modulating the expression of SMAD2, SMAD3 and SMAD4 in human BMSCs, we inve ...[more]

PMID: 28240243

Similar Datasets

Project description:IgA is the predominant antibody isotype at intestinal mucosae, where it plays a critical role in homeostasis and provides a first line of immune protection. Dysregulation of IgA production, however, can contribute to immunopathology, particularly in kidneys in which IgA deposition can cause nephropathy. Class-switch DNA recombination (CSR) to IgA is directed by TGF-β signaling, which activates Smad2 and Smad3. Activated Smad2/Smad3 dimers are recruited together with Smad4 to the IgH α locus Iα promoter to activate germline Iα-Cα transcription, the first step in the unfolding of CSR to IgA. Epigenetic factors, such as non-coding RNAs, particularly microRNAs, have been shown to regulate T cells, dendritic cells and other immune elements, as well as modulate the antibody response, including CSR, in a B cell-intrinsic fashion. Here we showed that the most abundant miRNA in resting B cells, miR-146a targets Smad2, Smad3 and Smad4 mRNA 3'UTRs and keeps CSR to IgA in check in resting B cells. Indeed, enforced miR-146a expression in B cells aborted induction of IgA CSR by decreasing Smad levels. By contrast, upon induction of CSR to IgA, as directed by TGF-β, B cells downregulated miR-146a, thereby reversing the silencing of Smad2, Smad3 and Smad4, which, once expressed, led to recruitment of Smad2, Smad3 and Smad4 to the Iα promoter for activation of germline Iα-Cα transcription. Deletion of miR-146a in miR-146a -/- mice significantly increased circulating levels of steady state total IgA, but not IgM, IgG or IgE, and heightened the specific IgA antibody response to OVA. In miR-146a -/- mice, the elevated systemic IgA levels were associated with increased IgA+ B cells in intestinal mucosae, increased amounts of fecal free and bacteria-bound IgA as well as kidney IgA deposition, a hallmark of IgA nephropathy. Increased germline Iα-Cα transcription and CSR to IgA in miR-146a -/- B cells in vitro proved that miR-146a-induced Smad2, Smad3 and Smad4 repression is B cell intrinsic. The B cell-intrinsic role of miR-146a in the modulation of CSR to IgA was formally confirmed in vivo by construction and OVA immunization of mixed bone marrow μMT/miR-146a -/- chimeric mice. Thus, by inhibiting Smad2, Smad3 and Smad4 expression, miR-146a plays an important and B cell intrinsic role in modulation of CSR to IgA and the IgA antibody response.

Dataset Information

SMAD3 and SMAD4 have a more dominant role than SMAD2 in TGFβ-induced chondrogenic differentiation of bone marrow-derived mesenchymal stem cells.

Publications

SMAD3 and SMAD4 have a more dominant role than SMAD2 in TGFβ-induced chondrogenic differentiation of bone marrow-derived mesenchymal stem cells.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets