Insulin‐Like Growth Factor Binding Protein 4 Enhances Cardiomyocytes Induction in Murine‐Induced Pluripotent Stem Cells

Abstract

Insulin-like growth factor binding protein 4 (IGFBP4) has been reported to play critical role in cardiomyocytes differentiation of embryonic stem cells (ESCs). But whether it promotes cardiomyocytes induction of iPSCs is unclear. In the present study, we aim to explore the role of IGFBP4 in the cardiogenesis of mouse iPSCs. We observed that IGFBP4 treatment at late stage during differentiation process of mouse iPSCs greatly enhanced the beating frequency of embryoid bodies (EBs). The expressions of Nkx2.5 (cardiac-specific transcription factor), α-MHC, α-actinin, and Troponin I (cardiac-specific protein) were significantly enhanced by IGFBP4 treatment. Immunostaining analysis showed that α-MHC, TNNT2 and connexin 43, typical cardiac markers, were obviously expressed in isolated cardiomyocytes from iPSCs with or without IGFBP4 treatment. Further study revealed that IGFBP4 had little effect on the apoptosis of EBs, but it significantly promoted the proliferation of cardiomyocytes from iPSCs characterized by higher ratio EdU positive cells in differentiated cardiomyocytes. We next observed that IGFBP4 inhibited β-catenin expression in cytosol of EBs at late stage during differentiation of iPSCs. Knockdown of β-catenin using a siRNA technique promoted the proliferation of differentiated cardiomyocytes and enhanced cardiomyocytes induction of iPSCs, suggesting that the effect of IGFBP4 on cardiomyocytes differentiation of iPSCs has relationship with β-catenin signaling pathway. In conclusion, IGFBP4 promotes cardiogenesis of iPSCs by enhancing the proliferation of differentiated cardiomyocytes through inhibiting β-catenin signaling.

Insulin‐like growth factor binding protein 4 inhibits proliferation of bone marrow mesenchymal stem cells and enhances growth of neurospheres derived from the stem cells

“…The requirement of β‐catenin for the growth of derived neurospheres was contrary to the inhibitory effects of β‐catenin on the proliferation of differentiated cardiomyocytes from embryonic stem cells and induced pluripotent stem cells . IGFBP‐4 was reported to promote cardiomyocyte differentiation by antagonizing the Wnt/β‐catenin pathway through direct interactions with Wnt receptors Frizzled and lipoprotein receptor‐related protein 6 (LRP6) .…”

“…4 One of IGFindependent actions of IGFBP-4 was identified to promote cardiogenesis of induced pluripotent stem cells through inhibiting β-catenin signalling. 6 IGFBP-4 was more highly expressed in senescent BMSCs than in young BMSCs. 7 Addition of IGFBP-4 protein induced senescence and apoptosis in young MSCs whereas immunodepletion of IGFBP-4 reduced apoptosis and promoted cell growth.…”

“…Some IGFBPs were also reported to have IGF‐independent actions which are mediated by interaction with cell surface “receptors” (such as integrins and pertussis toxin sensitive and insensitive G‐protein‐coupled receptors) or nuclear hormone receptors . One of IGF‐independent actions of IGFBP‐4 was identified to promote cardiogenesis of induced pluripotent stem cells through inhibiting β‐catenin signalling . IGFBP‐4 was more highly expressed in senescent BMSCs than in young BMSCs .…”

Age-Related Insulin-Like Growth Factor Binding Protein-4 Overexpression Inhibits Osteogenic Differentiation of Rat Mesenchymal Stem Cells

“…For example, IGFBP4 promotes cardiomyocyte differentiation of embryonic stem cells [29]. In the cardiogenesis of mouse pluripotent stem cells, IGFBP4 significantly enhances the proliferation of cardiomyocytes [30]. Overexpression of GATA-4 significantly increases MSC differentiation into a myocardial phenotype, which was associated with the upregulation of IGFBP4 [31].…”

Insulin-like growth factor binding proteins 4-6

“…IGFBP-4 was identified as an IGF-independent cardiogenic growth factor by inhibiting Wnt signalling via direct interaction with a Wnt receptor and coreceptor [25]. IGFBP-4 induced cardiomyocyte differentiation from pluripotent stem cells by inhibiting b-catenin signalling [26].…”