Quaking Is a Key Regulator of Endothelial Cell Differentiation, Neovascularization, and Angiogenesis

Abstract

The capability to derive endothelial cell (ECs) from induced pluripotent stem cells (iPSCs) holds huge therapeutic potential for cardiovascular disease. This study elucidates the precise role of the RNA‐binding protein Quaking isoform 5 (QKI‐5) during EC differentiation from both mouse and human iPSCs (hiPSCs) and dissects how RNA‐binding proteins can improve differentiation efficiency toward cell therapy for important vascular diseases. iPSCs represent an attractive cellular approach for regenerative medicine today as they can be used to generate patient‐specific therapeutic cells toward autologous cell therapy. In this study, using the model of iPSCs differentiation toward ECs, the QKI‐5 was found to be an important regulator of STAT3 stabilization and vascular endothelial growth factor receptor 2 (VEGFR2) activation during the EC differentiation process. QKI‐5 was induced during EC differentiation, resulting in stabilization of STAT3 expression and modulation of VEGFR2 transcriptional activation as well as VEGF secretion through direct binding to the 3′ UTR of STAT3. Importantly, mouse iPS‐ECs overexpressing QKI‐5 significantly improved angiogenesis and neovascularization and blood flow recovery in experimental hind limb ischemia. Notably, hiPSCs overexpressing QKI‐5, induced angiogenesis on Matrigel plug assays in vivo only 7 days after subcutaneous injection in SCID mice. These results highlight a clear functional benefit of QKI‐5 in neovascularization, blood flow recovery, and angiogenesis. Thus, they provide support to the growing consensus that elucidation of the molecular mechanisms underlying EC differentiation will ultimately advance stem cell regenerative therapy and eventually make the treatment of cardiovascular disease a reality. The RNA binding protein QKI‐5 is induced during EC differentiation from iPSCs. RNA binding protein QKI‐5 was induced during EC differentiation in parallel with the EC marker CD144. Immunofluorescence staining showing that QKI‐5 is localized in the nucleus and stained in parallel with CD144 in differentiated ECs (scale bar = 50 µm). stem cells 2017 Stem Cells 2017;35:952–966

miR‐200/375 control epithelial plasticity‐associated alternative splicing by repressing the RNA ‐binding protein Quaking

“…As both miR-200c and miR-375 act both on the mRNA level and on translation of QKI-5, this ZEB1/miR-200/miR-375/QKI-5 regulatory loop is particularly strong, producing the strongly mesenchymal expression pattern of QKI we observed in the panel of breast cancer cell lines that we examined, paralleling the mutually exclusive expression of miR-200c and ZEB1 . Since QKI has notable functions outside of EMT, including regulating neuronal (Larocque et al, 2005;Zhao et al, 2006;Hayakawa-Yano et al, 2017), smooth muscle and vascular (Noveroske et al, 2002;Li et al, 2003;van der Veer et al, 2013;Cochrane et al, 2017) cell function, and alternative splicing programmes during muscle cell (Hall et al, 2013) and monocyte (de Bruin et al, 2016a) differentiation, we propose that the ZEB1/miR-200c/miR-375/QKI-5 pathway may influence splicing outcomes that impact a broad range of cell differentiation contexts.…”

The RNA-binding protein QKI controls alternative splicing in vascular cells, producing an effective model for therapy

“…1C,D). Our laboratory has recently reported that the RBP QKI-5 holds a key role in EC differentiation, angiogenesis and neovascularisation (Cochrane et al, 2017). Since the field of RBPs is fast emerging, and RBPs are now recognised as powerful, versatile regulatory units, which play pivotal roles in the regulation of cell differentiation (Guallar and Wang, 2014), we hypothesised that QKI alternative splicing may play a role in determining the developmental fate of the vascular cell.…”

“…QKI alternative splicing isoform (QKI-5) has recently been identified by our laboratory to direct iPSC differentiation to an endothelial lineage through direct binding and stabilisation of STAT3, while iPS-ECs overexpressing QKI-5 enhanced repair in an in vivo model of hind limb ischaemia (Cochrane et al, 2017). Notably, QKI has been shown to be strongly induced in vascular injury, altering the expression of myocardin, a key driver of VSMC differentiation (van der Veer et al, 2013).…”

“…Since vascular cells are capable of derivation from a common developmental progenitor (Yamashita et al, 2000), and QKI-5 is instrumental in EC differentiation from iPSCs (Cochrane et al, 2017), we hypothesised that the alternative splicing isoform QKI-6 may play a role in facilitating key mechanisms of VSMC differentiation from iPSCs. Since QKI-6 is co-localised with spliceosomal proteins in the nucleus, it may hold a pivotal role in regulating alternative splicing controlling VSMC differentiation.…”

miRNA-Coordinated Schizophrenia Risk Network Cross-Talk With Cardiovascular Repair and Opposed Gliomagenesis

“…There is no doubt that miR-208-regulated QKI defines the phenotypic plasticity of the vascular smooth muscle cells (van der Veer et al, 2013;Cochrane et al, 2017). These functional pieces of evidence of the involvement of QKI into the development of cardiovascular conditions are also supported by the GWAS, which pointed at QKI as a contributor to coronary heart disease (Dehghan et al, 2016).…”