Na+/Ca2+ exchanger-1 protects against systolic failure in the Akitains2 model of diabetic cardiomyopathy via a CXCR4/NF-κB pathway.

Abstract

Diabetic cardiomyopathy is characterized, in part, by calcium handling imbalances associated with ventricular dysfunction. The cardiac Na(+)/Ca(2+) exchanger 1 (NCX1) has been implicated as a compensatory mechanism in response to reduced contractility in the heart; however, its role in diabetic cardiomyopathy remains unknown. We aimed to fully characterize the Akita(ins2) murine model of type 1 diabetes through assessing cardiac function and NCX1 regulation. The CXCL12/CXCR4 chemokine axis is well described in its cardioprotective effects via progenitor cell recruitment postacute myocardial infarction; however, it also functions in regulating calcium dependent processes in the cardiac myocyte. We therefore investigated the potential impact of CXCR4 in diabetic cardiomyopathy. Cardiac performance in the Akita(ins2) mouse was monitored using echocardiography and in vivo pressure-volume analysis. The Akita(ins2) mouse is protected against ventricular systolic failure evident at both 5 and 12 mo of age. However, the preserved contractility was associated with a decreased sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2a)/phospholamban ratio and increased NCX1 content. Direct myocardial injection of adenovirus encoding anti-sense NCX1 significantly decreased NCX1 expression and induced systolic failure in the Akita(ins2) mouse. CXCL12 and CXCR4 were both upregulated in the Akita(ins2) heart, along with an increase in IκB-α and NF-κB p65 phosphorylation. We demonstrated that CXCR4 activation upregulates NCX1 expression through a NF-κB-dependent signaling pathway in the cardiac myocyte. In conclusion, the Akita(ins2) type 1 diabetic model is protected against systolic failure due to increased NCX1 expression. In addition, our studies reveal a novel role of CXCR4 in the diabetic heart by regulating NCX1 expression via a NF-κB-dependent mechanism.

• Authors: Thomas J LaRocca, Frank Fabris, Jiqiu Chen, Daniel Benhayon, Shihong Zhang, LaTronya McCollum, Alison D Schecter, Joseph Y Cheung, Eric A Sobie, Roger J Hajjar, Djamel Lebeche
• Journal: American journal of physiology. Heart and circulatory physiology (Am J Physiol Heart Circ Physiol) Vol. 303 Issue 3 Pg. H353-67 (Aug 01 2012) ISSN: 1522-1539 [Electronic] United States
• PMID: 22610174 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• CXCR4 protein, mouse
• Chemokine CXCL12
• Cxcl12 protein, mouse
• Cxcr4 protein, rat
• Ins2 protein, mouse
• Insulin
• NF-kappa B
• Receptors, CXCR4
• Sodium-Calcium Exchanger
• sodium-calcium exchanger 1
• Calcium

Topics

• Action Potentials
• Animals
• Calcium (metabolism)
• Cells, Cultured
• Chemokine CXCL12 (metabolism)
• Diabetes Mellitus, Type 1 (complications, genetics, metabolism)
• Diabetic Cardiomyopathies (diagnostic imaging, etiology, genetics, metabolism, physiopathology, prevention & control)
• Diastole
• Disease Models, Animal
• Gene Knockdown Techniques
• Hemodynamics
• Insulin (genetics)
• Male
• Mice
• Myocytes, Cardiac (metabolism)
• NF-kappa B (metabolism)
• Phosphorylation
• Rats
• Rats, Sprague-Dawley
• Receptors, CXCR4 (metabolism)
• Signal Transduction
• Sodium-Calcium Exchanger (genetics, metabolism)
• Systole
• Ultrasonography
• Up-Regulation
• Ventricular Dysfunction, Left (diagnostic imaging, etiology, genetics, metabolism, physiopathology, prevention & control)
• Ventricular Function, Left