These data demonstrate that the detection of enterovirus RNA in the myocardium of patients with heart muscle disease at the time of initial investigation is associated with an adverse prognosis and that the presence of enterovirus RNA is an independent predictor of clinical outcome.

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Enteroviruses are well recognized in the aetiology of myocarditis. Molecular hybridization using enterovirus group-specific probes shows that virus can be detected in endomyocardial biopsies and persists in myocardium after the inflammation heals. Virus persistence is associated with the subsequent development of dilated cardiomyopathy, progressing to end-stage disease requiring cardiac transplantation. Infectious virus cannot usually be isolated from myocardium nor can virus-specific antigens be detected after the initial inflammatory stage. Patients with healed myocarditis or dilated cardiomyopathy may have no histological evidence of inflammation despite detection of virus-specific RNA sequences by molecular hybridization. Persisting enterovirus RNA in dilated cardiomyopathy is the strongest known predictor of poor prognosis. The molecular mechanism of virus persistence is the selection of defective virus mutants during the initial phase of disease.

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To identify new sequence elements in the promoter that affect splicing patterns of pre-mRNAs, we analyzed effects of different promoters on alternative splicing of model reporter genes. We compared the E1a alternative splicing pattern in transcripts expressed from the full-length cytomegalovirus, SV40 early, or a hybrid cytomegalovirus/SV40 early promoter and found that the hybrid promoter improved selection of the suboptimal E1a 5SS-1. Expressing RNA from the hybrid promoter also enhanced selection of suboptimal splice sites in other alternatively spliced reporter genes, demonstrating the generality of this effect. Unlike previously defined promoter elements shown to affect alternative splicing, which were located in the enhancer/upstream activating sequences, the motif identified in this work is positioned within the core promoter; it is comprised of eight T-residues directly upstream of the SV40 early TATA box. This motif was previously implicated in DNA bending and negative regulation of transcription. Together, these results suggest that the identity of transcription complex assembled in the core promoterdependent fashion can affect splice site selection during pre-mRNA splicing, perhaps by influencing the processivity of transcription elongation.Transcription initiation, elongation, and termination, as well as mRNA capping, splicing, and polyadenylation, are all interconnected, yet the specific mechanisms underlying these connections are not well understood. Such transcription-splicing connections were first demonstrated by different alternative splicing patterns observed depending on whether pre-mRNA splicing substrates were presynthesized or spliced co-transcriptionally (1, 2). Splicing patterns can also be affected by the rate of transcription elongation (e.g. 3-5 and reviewed in Ref. 6). A kinetic model was proposed to explain these findings; in this model, a slow RNA polymerase II (RNAPII) 4 elongation rate facilitates selection of suboptimal splice sites by the spliceosome, favoring inclusion of alternative exons (typically flanked by suboptimal splice signals), whereas a rapid RNAPII elongation rate favors skipping of alternatively spliced exons. Furthermore, these studies suggested that the RNAPII elongation rate is affected by the promoter identity (4 and reviewed in Ref. 6). Eukaryotic promoters typically contain a core segment that recruits general transcription factors (GTFs) and an upstream activating sequence (UAS) that provides binding sites for transcriptional activators (7). Transcription activation also involves the Mediator complex thought to facilitate interactions between activators and the preinitiation complex (PIC) as they assemble at the promoter (8). PIC assembly starts with binding of the GTF TFIID (composed of the TATA-binding protein TBP and associated TAFs) to the TATA box. The UAS and activators modulate TAF recruitment, which then affect subsequent recruitment of TFIIB, RNAPII, TFIIF, TFIIE, and TFIIH (9). Chromatin immunoprecipitation analyses suggest alternative pathways o...