hnRNP L is essential for myogenic differentiation and modulates myotonic dystrophy pathologies

Matthew S Alexander, Rylie M Hightower, Andrea L Reid, Alexis H Bennett, Lakshmanan Iyer, Donna K Slonim, Madhurima Saha, Genri Kawahara, Louis M Kunkel, Alan S Kopin, Vandana A Gupta, Peter B Kang, Isabelle Draper

Research output: Contribution to journalArticlepeer-review

Abstract

INTRODUCTION: RNA-binding proteins (RBPs) play an important role in skeletal muscle development and disease by regulating RNA splicing. In myotonic dystrophy type 1 (DM1), the RBP MBNL1 (muscleblind-like) is sequestered by toxic CUG repeats, leading to missplicing of MBNL1 targets. Mounting evidence from the literature has implicated other factors in the pathogenesis of DM1. Herein we sought to evaluate the functional role of the splicing factor hnRNP L in normal and DM1 muscle cells.

METHODS: Co-immunoprecipitation assays using hnRNPL and MBNL1 expression constructs and splicing profiling in normal and DM1 muscle cell lines were performed. Zebrafish morpholinos targeting hnrpl and hnrnpl2 were injected into one-cell zebrafish for developmental and muscle analysis. In human myoblasts downregulation of hnRNP L was achieved with shRNAi. Ascochlorin administration to DM1 myoblasts was performed and expression of the CUG repeats, DM1 splicing biomarkers, and hnRNP L expression levels were evaluated.

RESULTS: Using DM1 patient myoblast cell lines we observed the formation of abnormal hnRNP L nuclear foci within and outside the expanded CUG repeats, suggesting a role for this factor in DM1 pathology. We showed that the antiviral and antitumorigenic isoprenoid compound ascochlorin increased MBNL1 and hnRNP L expression levels. Drug treatment of DM1 muscle cells with ascochlorin partially rescued missplicing of established early biomarkers of DM1 and improved the defective myotube formation displayed by DM1 muscle cells.

DISCUSSION: Together, these studies revealed that hnRNP L can modulate DM1 pathologies and is a potential therapeutic target.

Original languageEnglish (US)
Pages (from-to)928-940
Number of pages13
JournalMuscle & Nerve
Volume63
Issue number6
Early online dateMar 2 2021
DOIs
StatePublished - Jun 2021

Bibliographical note

Funding Information:
The authors are grateful to Ci Chen (MCRI, TMC) for expert technical assistance. We thank Dr Marina Mora, Dr Sara Gibertini, and the Telethon Network of Genetic Biobanks for the DM1-diseased myoblast cell lines. The authors thank Dr Albrecht Bindereif (Justus Liebig University of Giessen, Germany) and Dr Stefan Stamm (University of Kentucky) for the human hnRNP L-FLAG expression plasmids. We thank Dr Susan Farmer and her staff for care and maintenance of our zebrafish. Finally, we thank the patients and their families who contributed the samples used in this study and helped to make this research possible. National Institute of Neurological Disorders and Stroke of the National Institutes of Health (NIH), Grant Number: F99/K00 Grant F99NS118718 (to R.M.H.); Eunice Kennedy Shriver National Institute of Child Health and Human Development of the NIH, Grant Number: 2T32HD071866 (to R.M.H.) and R01HD095897 (to M.S.A.); NIH NIAMS, Award Number: R21AR074006 (to M.S.A.); Muscular Dystrophy Association, Grant Number: MDA41854; Children's Miracle Network (to P.B.K.); Foundation Building Strength Grant (AFBS) and Evergreen Innovation Award (to V.A.G.); NIH National Institute of Arthritis and Musculoskeletal and Skin Diseases, Grant Number: R01AR064300 (to L.M.K.).

Funding Information:
The authors are grateful to Ci Chen (MCRI, TMC) for expert technical assistance. We thank Dr Marina Mora, Dr Sara Gibertini, and the Telethon Network of Genetic Biobanks for the DM1‐diseased myoblast cell lines. The authors thank Dr Albrecht Bindereif (Justus Liebig University of Giessen, Germany) and Dr Stefan Stamm (University of Kentucky) for the human hnRNP L‐FLAG expression plasmids. We thank Dr Susan Farmer and her staff for care and maintenance of our zebrafish. Finally, we thank the patients and their families who contributed the samples used in this study and helped to make this research possible. National Institute of Neurological Disorders and Stroke of the National Institutes of Health (NIH), Grant Number: F99/K00 Grant F99NS118718 (to R.M.H.); Eunice Kennedy Shriver National Institute of Child Health and Human Development of the NIH, Grant Number: 2T32HD071866 (to R.M.H.) and R01HD095897 (to M.S.A.); NIH NIAMS, Award Number: R21AR074006 (to M.S.A.); Muscular Dystrophy Association, Grant Number: MDA41854; Children's Miracle Network (to P.B.K.); Foundation Building Strength Grant (AFBS) and Evergreen Innovation Award (to V.A.G.); NIH National Institute of Arthritis and Musculoskeletal and Skin Diseases, Grant Number: R01AR064300 (to L.M.K.).

Publisher Copyright:
© 2021 Wiley Periodicals LLC.

Keywords

  • ascochlorin
  • hnRNP L
  • MBNL
  • myotonic dystrophy
  • smooth

PubMed: MeSH publication types

  • Journal Article

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