ATF4 CDS or pas deletion in cardiomyocyte in E11.5 mouse heart RNAseq

to ivestigate whether an intact PAS independently prevents readthrough regardless of gene body context, or whether selective PAS loss alone is sufficient to trigger transcriptional termination failure. we generated two complementary mouse models at the endogenous Atf4 locus. In the first, the coding sequence was deleted while the canonical PAS and its associated auxiliary elements were preserved (Atf4 ΔCDS), isolating the contribution of gene body disruption from defects in 3′ end processing. In the second, the canonical PAS and its auxiliary elements were selectively deleted while the coding sequence was fully retained (Atf4 ΔPAS), enabling direct assessment of whether loss of the full PAS regulatory module is sufficient to trigger transcriptional termination failure in vivo. The Atf4 ΔCDS model exhibits only modest transcriptional readthrough compared to the Atf4 ΔCDS+ΔPAS allele. Strikingly, selective loss of the canonical PAS does not induce detectable downstream readthrough; instead, RNAPII terminates at a cryptic upstream site within exon 3, generating truncated transcripts. These findings demonstrate that PAS loss alone is not sufficient to drive transcriptional readthrough at the endogenous Atf4 locus and reveal an unexpected plasticity in RNAPII termination site selection in vivo.