Effects of notch-1 knockdown on the proliferation and the differentiation of human osteoarthritis chondrocytes

Abstract

Conclusions:We have identified that the mobility, and the correlated activity, of the transcription factors SOX9 and RUNX2 is related to the differentiation of cells toward either the chondrogenic, osteogenic or adipogenic lineage. In addition, we observe different cell populations with different transcription factor mobility. Differentiated and undifferentiated cells could be segregated based on the mobility of the transcription factors. The population differentiated cells increased in time. To our knowledge, this is the first report of differential transcriptional dynamics of RUNX2 and SOX9 during chondrogenic, osteogenic and adipogenic differentiation of hMSCs. ; z Lab. for arthritis and bone biology, Fatima Res. Inst., Daegu, Republic of Korea; x Andong Gen. Hosp., Andong, Republic of Korea Purpose: Transglutamiase 2 (TG2) also known as tissue transglutamiase, is a calcium-dependent enzyme that has a variety of intracellular and extracellular substrates. It has been well known that TG2 increases in osteoarthritis (OA) tissue and can be used as a biomarker of OA. However, it has not been well elucidated the molecular mechanism of TG2 during the cartilage degradation in OA. Methods:The surgical destabilization of the medial meniscus (DMM) model is used to induce OA in 10-week-old male C57BL/6J mice. Primary chondrocytes were obtained from E15.5 long bones, and ZDON, a cellpermeable, peptide-based, irreversible inhibitor of TG2, was used to inhibit the function of TG2 and calcium ionophore to stimulate TG2. Results: TG2 expression was increased in articular cartilage and growth plate in surgical OA model. When treated with various growth factors, only TGFb1 increased TG2 expression of primary chondrocyte in a dosedependent manner. Intra-articular injection of specific TG2 inhibitor, ZDON, ameliorated the severity and MMP-13 expression in surgicallyinduced OA. ZDON attenuated MMP-3 and MMP-13 expression in TGFband calcium ionophore-treated chondrocytes in a Runx2-independent manner. TG2 activation by calcium ionophore induced phosphorylation of FoxO3a and ZDON decreased total FoxO3a as well as nuclear FoxO3a level. FoxO3a and TG2 were co-localized in primary chondrocytes and immunoprecipitation analysis revealed a direct interaction of FoxO3a and TG2, suggesting enhanced nuclear translocation of FoxO3a by TG2. Conclusions: our data provide an evidence of TG2 as an enhancer of FoxO3a-nuclear translocation which was responsible for the TG2dependent MMP-13 expression.

Pleiotropic Roles of NOTCH1 Signaling in the Loss of Maturational Arrest of Human Osteoarthritic Chondrocytes

“…Given the pleiotropic effects of NOTCH that are peculiar to the differentiation stage of the cells, we undertook the present study to characterize the effects of its silencing on proliferation and differentiation in vitro, exploiting both 2-D and 3-D culture models, established with primary human OA chondrocytes, in the perspective of elaborating a potential therapeutic strategy for OA management. Some preliminary findings presented in this manuscript have been already presented at an OARSI Congress in 2018 [ 28 ].…”