Abstract
Phosphodiesterase 3A (PDE3A), a member of the cGMP-inhibited cyclic nucleotide phosphodiesterase (PDE) family, plays important roles in oocyte maturation and vascular smooth muscle cell proliferation. However, the molecular mechanisms that regulate PDE3A gene expression remain largely unknown. In the present study, we investigated the transcriptional regulation of PDE3A, and found that the splicing factor proline- and glutamine-rich (SFPQ) protein modulated PDE3A mRNA levels. Multiple transcription start sites (TSS1, 2, and 3) were identified within the first exon of PDE3A using 5′-rapid amplification of cDNA ends (RACE). Variable expression levels of three PDE3A variants were also observed in human tissues and HeLa cells. Several putative SFPQ-binding sites were identified upstream of the regulatory region of PDE3A-TSSs using ChIP sequencing (ChIP-seq). Serum-induced PDE3A expression was affected by increasing the amount of SFPQ binding to the upstream regulatory region of PDE3A. In addition, transcription of PDE3A was lower in human cervical adenocarcinoma cells compared with normal cervical tissue. Furthermore, overexpression of PDE3A induced sensitivity to anticancer therapeutic agent, 6-(4-(diethylamino)-3-nitrophenyl)-5-methyl-4,5-dihydropyridazin-3(2H)-one (DNMDP), in HeLa cells. Taken together, these results suggest that SFPQ functions as a transcriptional activator of PDE3A, which is involved in the regulation of DNMDP sensitivity, offering a novel molecular target for the development of anticancer therapies.
Highlights
To maintain the normal cellular physiology, tight regulation of cAMP and cGMP signaling is pivotal, causing serious diseases if disrupted [1,2]
These results suggest a role for splicing factor proline and glutamine rich (SFPQ) in the regulation of the Phosphodiesterase 3A (PDE3A) gene
We identified SFPQ as a transcriptional regulator of the PDE3A gene
Summary
To maintain the normal cellular physiology, tight regulation of cAMP and cGMP signaling is pivotal, causing serious diseases if disrupted [1,2]. PDE3A is expressed in the cardiac tissue and vascular smooth muscle, platelets, oocytes, kidneys, and cervix. Pre-mRNA alternative splicing mechanisms, such as alternative promoter selection, are common ways to generate diversity of gene products [15,16]. Three hPDE3A protein variants (hPDE3A1/2/3) generated by hPDE3A-isoform 1 have been suggested to have different subcellular localizations in human myocardial cells and distinct roles in selective phosphorylation of protein targets [19]. We characterized the pre-mRNA alternative promoter and splicing patterns of PDE3A variants to gain insights into the mechanisms regulating the expression of different isoforms of this gene. We examined the mRNA levels of different isoforms in various human tissues and cells, and characterized the SFPQ-mediated transcriptional regulation of PDE3A gene expression. We found that hPDE3A expression was reduced in cervical cancer and the expression of hPDE3A increases the DNMDP sensitivity of cervical cancer cells
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