Submitted on October 24, 2006
Accepted on July 28, 2007
Membrane-type-1 Matrix Metalloproteinase Transcription and Translation in Myocardial Fibroblasts from Patients with Normal Left Ventrical Function and from Patients with Cardiomyopathy
Laura S. Spruill1, Abigail S. Lowry2, Robert E. Stroud2, Christina E. Squires2, Ira M. Mains3, English Chapman Flack2, Christy Beck2, John S. Ikonomidis2, A. Jackson Crumbley2, Paul J McDermott1, and Francis G. Spinale4*
1 Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States; RHJ Department of Veterans Affairs Medical Center, Charleston, South Carolina, United States
2 Division of Cardiothoracic Surgery, Department of Surgery, Medical University of South Carolina, Charleston, South Carolina, United States
3 Department of Surgery, Medical University of South Carolina, Charleston, South Carolina, United States
4 RHJ Department of Veterans Affairs Medical Center, Charleston, South Carolina, United States; Division of Cardiothoracic Surgery, Department of Surgery, Medical University of South Carolina, Charleston, South Carolina, United States
* To whom correspondence should be addressed. E-mail: wilburnm{at}musc.edu.
Past studies have identified that a unique type of matrix metalloproteinase, the membrane type-1 MMP (MT1-MMP) is increased within the left ventricle (LV) of patients with dilated cardiomyopathy (DCM). However, the cellular and molecular basis for this induction of MT1-MMP with DCM is unknown. LV myocardial biopsies from non-failing, reference normal patients (defined as LV ejection fraction >50%, elective coronary bypass surgery, no perfusion defect at biopsy site; n=6) and DCM patients (LV ejection fraction <20%, at transplant, n=5) were used to establish fibroblast cultures (FIBROS). Confluent LV FIBROS from culture passages 2-5 were measured with respect to MT1-MMP mRNA and protein levels, and the distribution of the MT1-MMP mRNA pool in ribosomal fractions. Total MT1-MMP mRNA within DCM FIBROS increased by over 140% and MT1-MMP protein increased by over 190% from reference normal FIBROS (both p<0.05). MT1-MMP mRNA in monosome fractions decreased by over 2-fold in DCM FIBROS compared to reference normal (p<0.05) and remained lower in polyribosomal fractions (ie; 15.7±5.2 vs 1.4±0.6% in polysomal fraction 6, p<0.05). These differences in DCM MT1-MMP FIBRO transcription and translation persisted throughout passages 2-5. The unique findings from this study demonstrated that elevated steady-state MT1-MMP mRNA and protein levels occurred in DCM FIBROS despite a decline in translational deficiency. These phenotypic changes ion DCM fibroblasts may provide the basis for developing cell specific pharmacological targets for control of MT1-MMP expression.
