(E) TIMP1 KD in CS MSCs during osteogenic development affects their expression of OSX.
SMAD3CA overexpression in WT MSCs during osteogenic differentiation reduces MMP13 expression and enhances TIMP1 and TIMP2 expression (n = 4). (D) Transfection of WT MSCs with SMAD3CA vectors affects the expression of ECM remodeling proteins. SMAD3 inhibition increases MMP13 expression and reduces TIMP1 and TIMP2 expression in CS osteoblasts (n = 4). (C) Inhibition of SMAD3 signaling alters the expression of ECM remodeling proteins in CS MSCs.
AR-S, alizarin red staining M13, recombinant human MMP13 siCtrl, siRNA control siT1, TIMP1 siRNA O.D, optical density. (B) Rescue of mineralization in CS MSCs upon transfection with TIMP1-specific siRNAs (n = 3). CS osteoblasts show reduced expression of MMP13 and increased expression of TIMP1 and TIMP2 (n = 3). All rights reserved.Īberrant expression of ECM remodeling proteins in CS osteoblasts (A) Dysregulation of ECM remodeling protein expression in CS osteoblasts. Thus, this study demonstrates that enhanced TIMP expression induced by hyperactivated SMAD3 signaling impairs the osteogenic development of CS MSCs via an inactivation of β-catenin signaling.Ĭostello syndrome TGF-β TIMP iPSCs osteogenesis β-catenin.Ĭopyright © 2021 The Authors. Knockdown of TIMPs permits normal differentiation of CS MSCs into osteoblasts and enhances β-catenin signaling in a RUNX2-independent manner. CS MSCs undergoing osteogenic differentiation also show reduced β-catenin signaling. We found that hyperactivation of SMAD3 signaling during the osteogenic differentiation of CS MSCs leads to aberrant expression of ECM remodeling proteins such as MMP13, TIMP1, and TIMP2. Although CS patient-derived iPSCs develop normally to produce mesenchymal stem cells (MSCs), the resulting CS MSCs show defective osteogenesis with reduced alkaline phosphatase activity and lower levels of bone mineralization. Here, we use CS induced pluripotent stem cells (iPSCs) undergoing osteogenic differentiation to investigate how dysregulation of extracellular matrix (ECM) remodeling proteins contributes to impaired osteogenesis.
Although CS patients have skeletal abnormalities, the role of mutated HRAS in bone development remains unclear. Costello syndrome (CS) is an autosomal dominant disorder caused by mutations in HRAS.
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