Abstract—The objective of the present study was to gain insight into the cooperative roles of Ets-1 and p300 in transcriptional regulation and expression of the Npr1 gene (coding for guanylyl cyclase-A/natriuretic peptide receptor-A). Overexpression of Ets-1 and p300 in mouse mesangial cells increased Npr1 promoter activity by 12-fold, natriuretic peptide receptor-A mRNA levels by 5-fold, and ANP-dependent intracellular accumulation of cGMP by 26-fold. Knockdown of Ets-1 and p300 expression by small interfering RNA inhibited Npr1 gene transcription by 90%. Sequential chromatin immunoprecipitation assay demonstrated a direct physical association between p300 and Ets-1 on binding to the Npr1 promoter, suggesting that a physical interaction between Ets-1 and p300 is important to enhance Npr1 gene transcription. Mutant p300 lacking histone acetyltransferase activity did not show a functional effect with Ets-1, suggesting that histone acetyltransferase activity of p300 is required for the cooperative interaction in modulating Npr1 gene transcription. Overexpression of wild-type adenovirus E1A significantly decreased the Npr1 promoter activity by 40%, whereas mutant E1A, which is incapable of binding to p300, did not show any effect. The results indicate that Npr1 gene transcription is critically controlled by histone acetyltransferase p300 and Ets-1. The present findings should yield important insights into the molecular signaling governing Npr1 gene transcription, an important regulator in the control of hypertension and cardiovascular events.