Apponi LH, Corbett AH, Pavlath GK. Control of mRNA stability contributes to low levels of nuclear poly(A) binding protein 1 (PABPN1) in skeletal muscle.
Skelet Muscle 2013;
3:23. [PMID:
24083404 PMCID:
PMC3879409 DOI:
10.1186/2044-5040-3-23]
[Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Accepted: 08/28/2013] [Indexed: 12/21/2022] Open
Abstract
Background
The nuclear poly(A) binding protein 1 (PABPN1) is a ubiquitously expressed protein
that plays critical roles at multiple steps in post-transcriptional regulation of
gene expression. Short expansions of the polyalanine tract in the N-terminus of
PABPN1 lead to oculopharyngeal muscular dystrophy (OPMD), which is an adult onset
disease characterized by eyelid drooping, difficulty in swallowing, and weakness
in the proximal limb muscles. Why alanine-expanded PABPN1 leads to muscle-specific
pathology is unknown. Given the general function of PABPN1 in RNA metabolism,
intrinsic characteristics of skeletal muscle may make this tissue susceptible to
the effects of mutant PABPN1.
Methods
To begin to understand the muscle specificity of OPMD, we investigated the
steady-state levels of PABPN1 in different tissues of humans and mice.
Additionally, we analyzed the levels of PABPN1 during muscle regeneration after
injury in mice. Furthermore, we assessed the dynamics of PABPN1 mRNA decay in
skeletal muscle compared to kidney.
Results
Here, we show that the steady-state levels of both PABPN1 mRNA and protein are
drastically lower in mouse and human skeletal muscle, particularly those impacted
in OPMD, compared to other tissues. In contrast, PABPN1 levels are increased
during muscle regeneration, suggesting a greater requirement for PABPN1 function
during tissue repair. Further analysis indicates that modulation of PABPN1
expression is likely due to post-transcriptional mechanisms acting at the level of
mRNA stability.
Conclusions
Our results demonstrate that PABPN1 steady-state levels and likely control of
expression differ significantly in skeletal muscle as compared to other tissues,
which could have important implications for understanding the muscle-specific
nature of OPMD.
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