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PYK2 regulates SERCA2 gene expression in neonatal rat ventricular myocytes
Maria C Heidkamp1, Brian T Scully, Kalpana Vijayan
1The Cardiovascular Institute, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA.
American Journal of Physiology. Cell Physiology
|April 15, 2005
Summary
Proline-rich tyrosine kinase 2 (PYK2) activation in heart cells reduces SERCA2 mRNA, impacting cardiac calcium handling. This PYK2 signaling cascade may contribute to heart failure by downregulating SERCA2 gene transcription.
Area of Science:
- Cardiology
- Molecular Biology
- Biochemistry
Background:
- Nonreceptor protein tyrosine kinase (PTK) proline-rich tyrosine kinase 2 (PYK2) is linked to left ventricular hypertrophy and heart failure.
- The precise role of PYK2 in these cardiac conditions remains unclear.
Purpose of the Study:
- To investigate if PYK2 overexpression activates MAPKs and downregulates SERCA2 mRNA in neonatal rat ventricular myocytes (NRVM).
- To elucidate the signaling pathways involved in PYK2-mediated SERCA2 regulation.
Main Methods:
- Overexpression of wild-type (WT), kinase-deficient (KD), and phosphorylation-deficient PYK2 mutants using adenoviruses (Adv) in NRVM.
- Analysis of SERCA2 mRNA levels via Northern blot and real-time RT-PCR.
- Assessment of MAPK activation (JNK1/2, p38(MAPK), ERK1/2) and SERCA2 promoter activity.
Main Results:
- PYK2 overexpression significantly decreased SERCA2 mRNA levels.
- Both kinase-dependent and phosphorylation-dependent pathways of PYK2 contributed to SERCA2 downregulation.
- PYK2 activated JNK1/2 and p38(MAPK) but not ERK1/2; combined activation of stress-activated protein kinases was necessary for SERCA2 reduction.
- PYK2 overexpression reduced SERCA2 promoter activity.
Conclusions:
- PYK2 signaling downregulates SERCA2 gene transcription in NRVM.
- A PYK2-dependent cascade may contribute to abnormal cardiac calcium handling in left ventricular hypertrophy and heart failure by reducing SERCA2 expression.