Unconjugated
Aberrant Ca2+ handling is a prominent feature of heart failure. Elucidation of the molecular mechanisms responsible for aberrant Ca2+ handling is essential for the development of strategies to blunt pathological changes in calcium dynamics. The peptidyl-prolyl cis-trans isomerase peptidyl-prolyl isomerase 1 (Pin1) is a critical mediator of myocardial hypertrophy development and cardiac progenitor cell cycle. However, the influence of Pin1 on calcium cycling regulation has not been explored. On the basis of these findings, the aim of this study is to define Pin1 as a novel modulator of Ca2+ handling, with implications for improving myocardial contractility and potential for ameliorating development of heart failure.
Pin1 gene deletion or pharmacological inhibition delays cytosolic Ca2+ decay in isolated cardiomyocytes. Paradoxically, reduced Pin1 activity correlates with increased sarco(endo)plasmic reticulum calcium ATPase (SERCA2a) and Na2+/Ca2+ exchanger 1 protein levels. However, SERCA2a ATPase activity and calcium reuptake were reduced in sarcoplasmic reticulum membranes isolated from Pin1-deficient hearts, suggesting that Pin1 influences SERCA2a function. SERCA2a and Na2+/Ca2+ exchanger 1 associated with Pin1, as revealed by proximity ligation assay in myocardial tissue sections, indicating that regulation of Ca2+ handling within cardiomyocytes is likely influenced through Pin1 interaction with SERCA2a and Na2+/Ca2+ exchanger 1 proteins.
Pin1 serves as a modulator of SERCA2a and Na2+/Ca2+ exchanger 1 Ca2+ handling proteins, with loss of function resulting in impaired cardiomyocyte relaxation, setting the stage for subsequent investigations to assess Pin1 dysregulation and modulation in the progression of heart failure.
© 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.
Autologous cardiac progenitor cell (CPC) therapy is a promising approach for treatment of heart failure (HF). There is an unmet need to identify inherent deficits in aged/diseased human CPCs (hCPCs) derived from HF patients in the attempts to augment their regenerative capacity prior to use in the clinical setting. Here we report significant functional correlations between phenotypic properties of hCPCs isolated from cardiac biopsies of HF patients, clinical parameters of patients and expression of the P2Y14 purinergic receptor (P2Y14 R), a crucial detector for extracellular UDP-sugars released during injury/stress. P2Y14 R is downregulated in hCPCs derived from HF patients with lower ejection fraction or diagnosed with diabetes. Augmenting P2Y14 R expression levels in aged/diseased hCPCs antagonizes senescence and improves functional responses. This study introduces purinergic signalling modulation as a potential strategy to rejuvenate and improve phenotypic characteristics of aged/functionally compromised hCPCs prior to transplantation in HF patients.
Autologous cardiac progenitor cell therapy is a promising alternative approach to current inefficient therapies for heart failure (HF). However, ex vivo expansion and pharmacological/genetic modification of human cardiac progenitor cells (hCPCs) are necessary interventions to rejuvenate aged/diseased cells and improve their regenerative capacities. This study was designed to assess the potential of improving hCPC functional capacity by targeting the P2Y14 purinergic receptor (P2Y14 R), which has been previously reported to induce regenerative and anti-senescence responses in a variety of experimental models. c-Kit+ hCPCs were isolated from cardiac biopsies of multiple HF patients undergoing left ventricular assist device implantation surgery. Significant correlations existed between the expression of P2Y14 R in hCPCs and clinical parameters of HF patients. P2Y14 R was downregulated in hCPCs derived from patients with a relatively lower ejection fraction and patients diagnosed with diabetes. hCPC lines with lower P2Y14 R expression did not respond to P2Y14 R agonist UDP-glucose (UDP-Glu) while hCPCs with higher P2Y14 R expression showed enhanced proliferation in response to UDP-Glu stimulation. Mechanistically, UDP-Glu stimulation enhanced the activation of canonical growth signalling pathways ERK1/2 and AKT. Restoring P2Y14 R expression levels in functionally compromised hCPCs via lentiviral-mediated overexpression improved proliferation, migration and survival under stress stimuli. Additionally, P2Y14 R overexpression reversed senescence-associated morphology and reduced levels of molecular markers of senescence p16INK4a , p53, p21 and mitochondrial reactive oxygen species. Findings from this study unveil novel biological roles of the UDP-sugar receptor P2Y14 in hCPCs and suggest purinergic signalling modulation as a promising strategy to improve phenotypic properties of functionally impaired hCPCs.
© 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.