Abstract
Transcripts of alpha-fetoprotein (Afp), H19, and insulin-like growth factor 2 (Igf2) genes are highly expressed in mouse fetal liver, but decrease drastically during maturation. While transcriptional regulation of these genes has been well studied, the post-transcriptional regulation of their developmental decrease is poorly understood. Here, we show that shortening of poly(A) tails and subsequent RNA decay are largely responsible for the postnatal decrease of Afp, H19, and Igf2 transcripts in mouse liver. IGF2 mRNA binding protein 1 (IMP1), which regulates stability and translation efficiency of target mRNAs, binds to these fetal liver transcripts. When IMP1 is exogenously expressed in mouse adult liver, fetal liver transcripts show higher expression and possess longer poly(A) tails, suggesting that IMP1 stabilizes them. IMP1 declines concomitantly with fetal liver transcripts as liver matures. Instead, RNA-binding proteins (RBPs) that promote RNA decay, such as cold shock domain containing protein E1 (CSDE1), K-homology domain splicing regulatory protein (KSRP), and CUG-BP1 and ETR3-like factors 1 (CELF1), bind to 3′ regions of fetal liver transcripts. These data suggest that transitions among RBPs associated with fetal liver transcripts shift regulation from stabilization to decay, leading to a postnatal decrease in those fetal transcripts.
Highlights
Genes that are expressed in fetal and neonatal stages, but inactivated in adults, participate in early developmental processes and maintenance of immature tissue characteristics
We provide evidence that CCR4-NOT complex-mediated RNA decay is involved in the postnatal decrease of Afp, H19, and insulin-like growth factor 2 (Igf2) transcripts
This study reveals contributions of post-transcriptional mechanisms to postnatal repression of fetal liver genes
Summary
Genes that are expressed in fetal and neonatal stages, but inactivated in adults, participate in early developmental processes and maintenance of immature tissue characteristics. Among post-transcriptional mechanisms, translational repression and RNA decay are relevant to decreased mRNA levels. When mice lack expression of microRNA-122 (an abundant liver miRNA), Dicer, which produces mature miRNAs, or core subunits of the CCR4-NOT complex in liver, enhanced expression of Afp, H19, and Igf transcripts is detected in adult livers compared to corresponding controls [29,30,31,32,33], suggesting that post-transcriptional mechanisms are responsible for the postnatal decrease of fetal liver transcripts. We provide evidence that CCR4-NOT complex-mediated RNA decay is involved in the postnatal decrease of Afp, H19, and Igf transcripts. Our analyses show that different RBPs bind to 3 regions of Afp, H19, and Igf transcripts, depending on liver developmental stages. Poly(A) Tail Elongation and Increased Levels of Fetal Liver Transcripts in Imp1-Transgenic Mice. WVTalmueicseinaregrsaept hs reptroes1e. nVtamlueasnins g±rasepmhs. r*epr
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have