38. Discovery of Mitochondrial Protein Biomarkers of Atrial Fibrillation using Unique Human Tissue Samples
Poster: Tue 6:30-7:30PM
Maryam Goudarzi
George Mason University
Maryam Goudarzi, George Mason University, Manassas, VA
Mark Ross, George Mason University, Manassas, VA
Weidong Zhou, George Mason University, Manassas, VA
Amy Van Meter, George Mason University, Manassas, VA
Jianghong Deng, George Mason University, Manassas, VA
Lance Liotta, George Mason University, Manassas, VA
Emanuel Petricoin, George Mason University, Manassas, VA,
Lisa Martin, Inova Heart & Vascular Institute, Falls Church, VA
Chidima Martin, Inova Heart & Vascular Institute, Falls Church, VA
Niv Ad, Inova Heart & Vascular Institute, Falls Church, VA
Atrial fibrillation (AF) is the most common cardiac arrhythmia, currently affecting 2.2 million Americans and accounting for 50,000 strokes annually in the United States. AF has been observed to be refractory to anti-arrhythmic drugs and extensive catheter and surgical ablations. Our biochemical understanding of this condition is limited, and there are no consistent biomarkers for AF. Our previous studies suggest involvement of atrial mitochondria in AF development. Therefore, our research objective is to determine differential mitochondrial protein expression in a unique set of human atrial specimens from patients with and without AF in order to identify candidate protein biomarkers of AF. In this study we combined two powerful protein analytical techniques, mass spectrometry (MS) and reverse phase protein microarray (RPMA), in a targeted analysis of mitochondrial protein fractions isolated from right atrial tissue of 10 AF patients and 10 non-AF control patients who underwent open heart surgery.

Approximately 700 proteins were identified in MS analyses of mitochondrial fractions isolated from atrial tissue samples of AF and non-AF patients, and approximately 5% of the proteins were found to be differentially expressed between the two sample sets. The differential expression (AF > non-AF) of four selected candidate biomarkers; four and a half LIM (FHL2), destrin, heat shock protein 2 (Hsp27), and chaperonin containing TCP1 (CCT5), was verified by RPMA, which is an antibody-based protein microarray technology. Involvement in AF development has been reported in other studies for the LIM domain-containing proteins such as FHL2, which is engaged in atrial arrhythmogenesis, and for HSP27 which once induced is reported to protect against atrial remodeling. The latter case is consistent with the observed greater abundance in AF atrial tissue. This is the first time that destrin and CCT5 have been implicated with AF. We plan to use MS and RPMA to verify the differential expression of these four candidate biomarkers in a larger blinded sample set and ultimately in patient serum samples.

Our studies yielded four candidate AF biomarker proteins and new insights into the changes that occur in atrial mitochondrial protein expression as a result of AF onset. This information enhances our knowledge of the role of mitochondria in AF development and pathogenesis. Further, the use of high resolution MS and novel protein microarray technology for differentially expressed protein identification and verification, respectively, constitutes a new and effective strategy for discovery of biomarkers of human cardiac disease.
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