Transcription factor MEF2A mutations in patients with coronary artery disease

Abstract

Coronary artery disease (CAD), including its most serious complication myocardial infraction (MI), is the leading cause of death in the US and developed countries. We recently discovered that a seven-amino acid deletion in MEF2A, a transcription factor with a high level of expression in the endothelium of coronary arteries, co-segregates with CAD/MI in one family, and it suppresses transcription activation activity of MEF2A by a dominant-negative mechanism. In this study, we used single-strand conformation polymorphism and DNA sequence analyses to identify mutations in MEF2A in 207 independent CAD/MI patients and 191 controls with normal angiograms. We identified three novel mutations in exon 7 of MEF2A in four of 207 CAD/MI patients (1.93%). No mutations were detected in the 191 controls. The mutations identified here include N263S identified in two independent CAD patients, P279L in one patient and his father with the diagnosis of CAD and G283D in one patient. These mutations are clustered within or close to the major transcriptional activation domain of MEF2A. They significantly reduce the transcriptional activation activity of MEF2A and act by a loss-of-function mechanism. The gene carriers with loss-of-function mutations appear to be associated with less severe CAD. These results suggest that CAD/MI can result from a spectrum of MEF2A transcription dysfunctions ranging from loss-of-function to dominant-negative suppression and that a significant percent of the CAD/MI population (1.93%) may carry mutations in MEF2A, although further definition of the prevalence of MEF2A mutations is warranted.

Figure 1

MEF2A missense mutation G263S in CAD patient GB04146. (A) Results of SSCP analysis showing an aberrant SSCP conformer (indicated by an arrow). N, normal control. The abnormal SSCP band was also detected in CAD patient GB05072, but was not seen in 200 controls. (B) Sequence analysis of the normal (WT) and aberrant (G263S) SSCP conformers revealed an A to G substitution at codon 263 in exon 7 of MEF2A. This mutation causes substitution of amino acid residue asparagines by serine (C).

Figure 2

Identification of MEF2A mutation P279L in CAD patient GB00305. Figure caption is as described in the legend to Figure 1.

Figure 3

Identification of MEF2A mutation G283D in CAD patient GB04583. Figure caption is as described in the legend to Figure 1.

Figure 4

(A) Structure of MEF2A protein with CAD/MI-associated mutations indicated. The MEF2A gene consists of 11 exons and encodes a 507 amino acid protein. The MADS domain and MEF2 domain at the N-terminal region are responsible for DNA binding, dimerization and interaction with other transcription factor. The transcription activation domain is locate in the middle portion and the C-terminal region is responsible for nuclear localization site (NLS). (B) The effect of missense mutations of MEF2A on transcription activation activity in the presence (+) or absence (−) of GATA-1. Transcriptional activity is shown as relative luciferase activity on the y-axis. The transcriptional activity for the vector alone was set arbitrarily to 1. WT, wild-type. Inset: western blot analysis to determine whether mutant MEF2A were successfully expressed in transfected HeLa cells. C, empty vector control; WT, lane with lysate from HeLa cells containing expressed wild-type MEF2A; N263S, P279L, G283D, lanes with lysates from HeLa cells containing expressed MEF2A proteins with corresponding mutation.