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Post‐Transcriptional Modulation of MCL1 by PTBP1 Regulates Cellular Apoptosis Induced by Antitubulin Chemotherapeutics
Author(s) -
Cui Jia
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.774.12
Subject(s) - mcl1 , polypyrimidine tract binding protein , gene knockdown , microbiology and biotechnology , biology , rna binding protein , messenger rna , propidium iodide , immunoprecipitation , cancer research , apoptosis , gene , programmed cell death , downregulation and upregulation , genetics
Background Myeloid Cell Leukemia 1 (MCL1), an anti‐apoptotic Bcl‐2 family protein, is a key regulator of intrinsic apoptosis. Normal cells require strict control over MCL1 expression and aberrant MCL1 expression has been shown linked to the emergence of various diseases and chemoresistance. Previous studies have detailed how MCL1 expression is regulated by multiple mechanisms both transcriptionally and translationally. However, characterization of the post‐transcriptional regulators of MCL1 mRNA is limited. Polypyrimidine tract binding protein 1 (PTBP1) is a known regulator of post‐transcriptional gene expression that can control mRNA splicing, translation, stability, and localization. In the described study we characterize the impact that PTBP1 has on MCL1 expression, its molecular mechanisms, and its roles on cellular apoptosis. Methods Cross‐linking Immunoprecipitation (CLIP)‐seq data analysis and RNA immunoprecipitation (RIP) were performed to analyze protein interactions with RNA and map the RNA binding sites on the genes of interests. RNA half‐life was measured by treating cells with Actinomycin D and extracting total RNA at different time point. Cell viability was measured by the MTS assay and apoptosis was assessed by Annexin V/Propidium Iodide (PI) staining followed by flow cytometry analysis. Results Our studies demonstrate that PTBP1 binds to MCL1 mRNA and that knockdown of PTBP1 up‐regulates MCL1 expression in cancer. Mechanistically, PTBP1 silencing stabilizes MCL1 mRNA. We further identify that this post‐transcriptional regulation is via the Argonaute2 (Ago2)‐mediated microRNA targeting to MCL1 . Moreover, we show that PTBP1 down‐regulation is anti‐apoptotic to antitubulin chemotherapeutics in a MCL1‐dependent manner. Conclusions Our findings suggest that PTBP1 is a novel post‐transcriptional regulator of MCL1 mRNA by which it controls apoptotic response to antitubulin chemotherapeutics. Support or Funding Information This research was funded by grants from the UAB Comprehensive Cancer Center Young Supporters Board, NIH grants R01 GM117391 (to WJP), and the UAB HHMI Med into Grad Fellowship (to JC).