Poster abstracts
Poster number 28 submitted by Sandip Chorghade
Postnatal Silencing of Nuclear Poly(A) Binding Protein (PABPN1) Regulates Cardiac Gene Expression and Function
Sandip Chorghade,Joe Seimetz,Subhashish Natua,Bo Zhang,Chaitali Misra, (Department of Biochemistry,University of Illinois Urbana-Champaign.), Qinyu Hao,Kananganattu V. Prasanth (Department of Cell and Developmental Biology,University of Illinois Urbana-Champaign.), Xander Wehrens (department of Molecular Physiology and Biophysics, Baylor College of Medicine), Jiwang Chen (Department of Medicine, University of Illinois Chicago), Auinash Kalsotra (Department of Biochemistry,University of Illinois Urbana-Champaign)
Abstract:
The nuclear poly(A) binding protein (PABPN1) is an evolutionarily conserved protein with ubiquitous expression, orchestrating various aspects of mRNA processing in the cell, including 3’-poly(A) tail elongation and alternative polyadenylation (ApA). In this study, we unveil a crucial regulatory role for PABPN1 in postnatal heart development across humans, mice, and rats, with profound implications for cardiac-specific gene expression profiles.
Employing single-molecule RNA imaging and nucleo-cytoplasmic fractionations, we elucidate the post-transcriptional silencing mechanism of PABPN1 during development. This silencing event is characterized by a dramatic shift in the subcellular localization of PABPN1 mRNA; while neonatal cardiomyocytes exhibit cytoplasmic mRNA localization, adult cardiomyocytes manifest partially spliced, nuclear-retained, and translationally inaccessible PABPN1 mRNA.
Conversely, in failing human hearts and mouse models of hypertrophy and heart failure, PABPN1 protein levels surge. We further demonstrate that acute stress-related stimuli can induce complete splicing and translocation of nuclear-sequestered PABPN1 mRNA to the cytoplasm. Notably, cardiomyocyte-specific conditional loss- and gain-of-function studies underscore the pivotal role of PABPN1, with its premature elimination or persistent expression in mouse myocardium leading to severe structural and functional abnormalities, culminating in heart failure and fatality.
Utilizing nanopore-based direct RNA sequencing and high-resolution Illumina sequencing, we identify widespread alterations in ApA and poly(A) tail lengths of cardiac transcripts during development. A substantial subset of these changes is contingent upon the postnatal silencing of PABPN1. Intriguingly, the reintroduction of PABPN1 triggers a comprehensive reversal of poly(A) site utilization, tail length modulation, and translational efficiency, particularly impacting transcripts associated with maladaptive cardiac cell growth.
Collectively, our findings underscore the significance of developmental PABPN1 silencing, orchestrated through regulated mRNA splicing and localization, in shaping the postnatal maturation and function of the heart.
Keywords: PABPN1 , Postnatal Heart development, Intron Retention