Key Points
- To determine how transcription factors GATA-4 and Nkx-2.5 cooperate to regulate cardiac alpha-actin promoter activity during early cardiac gene expression.
- Assayed transcriptional coactivation of the cardiac alpha-actin promoter and synthetic Nkx-2.5 response elements in heterologous CV-1 fibroblasts.
- Mapped interactive protein regions using truncation and deletion mutants of Nkx-2.5 and GATA-4.
- GATA-4 and Nkx-2.5 synergistically coactivate the cardiac alpha-actin promoter, requiring Nkx-2.5's homeodomain and N-terminal activation domain alongside GATA-4's second zinc finger.
- Removal of the Nkx-2.5 C-terminal inhibitory domain stimulated transcriptional activity and DNA binding to levels comparable to wild-type coactivation by GATA-4.
Structured PICO
PPopulationHeterologous CV-1 fibroblasts
IInterventionCo-expression of transcription factors Nkx-2.5 and GATA-4
OOutcomeTranscriptional activation of the cardiac alpha-actin (alphaCA) promoter and a minimal promoter containing Nkx-2.5 DNA binding sitessurrogate
The study demonstrates that cardiac alpha-actin promoter activity is regulated through combinatorial interactions of cardiac tissue-enriched transcription factors Nkx-2.5, GATA-4, and SRF.