GREM1 inhibits osteogenic differentiation, senescence and BMP transcription of adipose-derived stem cells

Abstract

<b>Purpose</b>: Adipose-derived stem cells (ADSCs) are ideal for cell-based therapies to support bone regeneration. It is vital to understand the critical genes and molecular mechanisms involved in the functional regulation of ADSCs for enhancing bone regeneration. In the present study, we investigated the Gremlin 1 (GREM1) effect on ADSCs osteogenic differentiation and senescence.<b>Materials and methods</b>: The <i>in vitro</i> ADSCs osteogenic differentiation potential was evaluated by determining alkaline phosphatase (ALP) activity, mineralization ability, and the expression of osteogenic markers. Cell senescence is determined by SA-β-gal staining, telomerase assay, and the expression of aging markers.<b>Results</b>: GREM1 overexpression in ADSCs reduced ALP activity and mineralization, inhibited the expression of osteogenic related genes <i>OCN, OPN, DSPP, DMP1</i>, and <i>BSP</i>, and key transcription factors, <i>RUNX2</i> and <i>OSX</i>. GREM1 knockdown in ADSCs enhanced ALP activity and mineralization, promoted the expression of <i>OCN, OPN, DSPP, DMP1, BSP, RUNX2</i>, and <i>OSX</i>. GREM1 overexpression in ADSCs reduced the percent SA-β-Gal positive cells, <i>P16</i> and <i>P53</i> expressions, and increased telomerase activity. GREM1 knockdown in ADSCs increased the percentage of SA-β-Gal positive cells, <i>P16</i> and <i>P53</i> expressions, and reduced telomerase activity. Furthermore, GREM1 reduced the mRNA expression levels of BMP2, BMP6, and BMP7.<b>Conclusions</b>: In summary, our findings suggested that GREM1 inhibited ADSCs senescence and osteogenic differentiation and antagonized BMP transcription.