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Oppositional poly(A) tail length regulation by FMRP and CPEB1
Jihae Shin1, Ki Young Paek1, Lies Chikhaoui2
1Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
RNA (New York, N.Y.)
|February 26, 2022
Summary
Fragile X mental retardation protein (FMRP) regulates poly(A) tail length, impacting RNA processing. Loss of FMRP increases poly(A) tail length, revealing a novel role in RNA regulation.
Area of Science:
- Molecular Biology
- RNA Biology
- Neuroscience
Background:
- Polyadenylation, the addition of a poly(A) tail to mRNA, is crucial for RNA stability and translation.
- Cytoplasmic polyadenylation is regulated by RNA-binding proteins like CPEB1, which recruits poly(A) polymerases GLD2 and GLD4.
- The role of other RNA-binding proteins in this process, particularly in relation to GLD4, remains incompletely understood.
Purpose of the Study:
- To identify novel RNA-binding proteins that interact with the poly(A) polymerase GLD4.
- To investigate the role of Fragile X mental retardation protein (FMRP) in regulating poly(A) tail length.
- To elucidate FMRP's contribution to cytoplasmic polyadenylation and RNA regulation.
Main Methods:
- Double-tagged GLD4 expression in U87MG cells followed by sequential immunoprecipitation and mass spectrometry to identify interacting proteins.
- TAIL-seq (Tail-length Analysis via Integrated Long-read Sequencing) in wild-type and FMRP-deficient HEK293 cells to assess poly(A) tail lengths.
- Direct RNA nanopore sequencing of mouse brain cortex from wild-type and FMRP-deficient individuals to analyze polyadenylation patterns.
Main Results:
- Mass spectrometry identified FMRP as an RNA-binding protein that coprecipitates with GLD4.
- Loss of FMRP led to an overall increase in poly(A) tail length in HEK293 cells and for specific mRNAs.
- Analysis of mouse brain cortex revealed both increases and decreases in poly(A) tail lengths in FMRP-deficient samples.
- Loss of CPEB1 resulted in the expected decrease in poly(A) tail length, validating experimental approaches.
Conclusions:
- FMRP plays a significant role in regulating poly(A) tail length, extending its known functions in RNA regulation.
- The findings suggest FMRP acts as a modulator of cytoplasmic polyadenylation, potentially interacting with the GLD4-CPEB1 complex.
- This study uncovers a new layer of RNA regulation mediated by FMRP, with implications for Fragile X syndrome and other neurological disorders.
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