Molecular Characterization and Promoter Activity Analysis of the Porcine Convergent Gene Pair ABCF1 and PPP1R10

The intergenic regions of porcine convergent gene pairs frequently maintain an open chromatin configuration with a permissive transcriptional microenvironment, rendering them promising candidates for genomic safe harbors (GSHs). However, the molecular features and promoter activities of the convergent gene pair ABCF1 and PPP1R10 remain uncharacterized, impeding the utilization of their potential as GSHs. To address this, we systematically predicted cis-regulatory elements (including CpG islands) of the two genes in silico, evaluated the transcriptional activities of serially truncated promoter fragments by dual-luciferase reporter assays in porcine fetal fibroblasts (PFFs) and PK-15 cells, compared their promoter regions across seven species, and characterized the protein architectures and flanking genomic landscapes. The ABCF1 promoter contained canonical TATA, CCAAT, and GC boxes alongside three CpG islands, and its shortest fragment, P217 (−217 to −1 bp), exhibited the highest activity in both cell lines. The PPP1R10 promoter possessed a triple TATA-box arrangement without detectable CpG islands, and its core fragment P211 (−211 to −1 bp) exhibited the highest activity among all truncated fragments in both cell lines and showed numerically higher activity than the simian virus 40 (SV40) promoter in PK-15 cells. No canonical oncogenes were identified within 100 kb upstream or downstream of the intergenic region between the two genes. Both ABCF1 and PPP1R10 are intracellular soluble proteins lacking transmembrane domains. ABCF1 is predominantly composed of α-helices, localizes in the cytoplasm and at the nuclear membrane, and modulates cytoplasmic translation. By contrast, PPP1R10 is enriched in random coils, specifically associates with nuclear chromatin, and participates in the PP1 phosphatase regulatory network. Taken together, our study delineates the core active promoter regions of both genes and highlights the potential of this chromosomal interval as a candidate genomic safe-harbor locus, a hypothesis awaiting further experimental validation.