ILK Induces Cardiomyogenesis in the Human Heart

Abstract

BackgroundIntegrin-linked kinase (ILK) is a widely conserved serine/threonine kinase that regulates diverse signal transduction pathways implicated in cardiac hypertrophy and contractility. In this study we explored whether experimental overexpression of ILK would up-regulate morphogenesis in the human fetal heart.Methodology/Principal FindingsPrimary cultures of human fetal myocardial cells (19–22 weeks gestation) yielded scattered aggregates of cardioblasts positive for the early cardiac lineage marker nk×2.5 and containing nascent sarcomeres. Cardiac cells in colonies uniformly expressed the gap junction protein connexin 43 (C×43) and displayed a spectrum of differentiation with only a subset of cells exhibiting the late cardiomyogenic marker troponin T (cTnT) and evidence of electrical excitability. Adenovirus-mediated overexpression of ILK potently increased the number of new aggregates of primitive cardioblasts (p<0.001). The number of cardioblast colonies was significantly decreased (p<0.05) when ILK expression was knocked down with ILK targeted siRNA. Interestingly, overexpression of the activation resistant ILK mutant (ILKR211A) resulted in much greater increase in the number of new cell aggregates as compared to overexpression of wild-type ILK (ILKWT). The cardiomyogenic effects of ILKR211A and ILKWT were accompanied by concurrent activation of β-catenin (p<0.001) and increase expression of progenitor cell marker islet-1, which was also observed in lysates of transgenic mice with cardiac-specific over-expression of ILKR211A and ILKWT. Finally, endogenous ILK expression was shown to increase in concert with those of cardiomyogenic markers during directed cardiomyogenic differentiation in human embryonic stem cells (hESCs).Conclusions/SignificanceIn the human fetal heart ILK activation is instructive to the specification of mesodermal precursor cells towards a cardiomyogenic lineage. Induction of cardiomyogenesis by ILK overexpression bypasses the requirement of proximal PI3K activation for transduction of growth factor- and β1-integrin-mediated differentiation signals. Altogether, our data indicate that ILK represents a novel regulatory checkpoint during human cardiomyogenesis.

Prenatal Exposure to Dexamethasone in the Mouse Alters Cardiac Growth Patterns and Increases Pulse Pressure in Aged Male Offspring

“…Also, in the hearts of growth restricted E12.5 mouse fetuses (induced by 6 h of 8% oxygen prior to E12.5) VEGFa mRNA was increased 1.9 fold, but no changes were reported in other growth factors measured such as FGF-2 mRNA [44]. Although the expression of the genes selected in this study were not changed during DEX exposure, it is likely that other relevant genes may have been affected such as the recently identified novel cardiotropic factor integrin-linked kinase [45].…”

Identification of ILK as a critical regulator of VEGFR 3 signalling and lymphatic vascular growth

“…Recently published studies revealed the importance of the cardiac lymphatic vasculature and its remodelling during the recovery phase after myocardial infarction (MI) (Ishikawa et al, 2007;Klotz et al, 2015;Henri et al, 2016;Tatin et al, 2017). Notably, the importance of ILK in cardiomyocytes and in regulating cardiac function was previously reported by several publications (Bendig et al, 2006;Lu et al, 2006;White et al, 2006;Ding et al, 2009;Gu et al, 2012;Traister et al, 2012). ILK protein is expressed in LECs sorted from the adult mouse heart (Appendix Fig S6D); however, to our knowledge, the function of ILK in cardiac lymphatic vessels has not yet been analysed.…”

Sexual dimorphism in cardiac transcriptome associated with a troponin C murine model of hypertrophic cardiomyopathy

“…Integrin‐linked kinase (ILK), now known as a mechanoreceptor protein and the physical linker for integrins with the actin cytoskeleton, regulates a variety of signal transduction pathways associated with both cardiac hypertrophy and contractility/force transduction (Lu et al, 2006; Traister et al, 2012, 2014). It forms the IPAP1 complex with PINCH1 and α‐parvin proteins, which are linked to cell adhesion, motility, and fibroblast and epithelial cell survival (Chen et al, 2005).…”