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Stefanovic L, Gordon BH, Silvers R, Stefanovic B. Characterization of Sequence-Specific Binding of LARP6 to the 5' Stem-Loop of Type I Collagen mRNAs and Implications for Rational Design of Antifibrotic Drugs. J Mol Biol 2022; 434:167394. [PMID: 34896113 PMCID: PMC8752511 DOI: 10.1016/j.jmb.2021.167394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/29/2021] [Accepted: 12/01/2021] [Indexed: 02/01/2023]
Abstract
Excessive synthesis of type I collagen is a hallmark of fibrotic diseases. Binding of La-related protein 6 (LARP6) to the 5' stem-loop (5'SL) of collagen mRNAs regulates their translation leading to an unnaturally elevated rate of collagen biosynthesis in fibrosis. Previous work suggested that LARP6 needs two domains to form stable complex with 5'SL RNA, the La domain and the juxtaposed RNA recognition motif (RRM), jointly called the La-module. Here we describe that La domain of LARP6 is necessary and sufficient for recognition of 5'SL in RNA sequence specific manner. A three-amino-acid motif located in the flexible loop connecting the second α-helix to the β-sheet of the La domain, called the RNK-motif, is critical for binding. Mutation of any of these three amino acids abolishes the binding of the La domain to 5'SL. The major site of crosslinking of LARP6 to 5'SL RNA was mapped to this motif, as well. The RNK-motif is not found in other LARPs, which cannot bind 5'SL. Presence of RRM increases the stability of complex between La domain and 5'SL RNA and RRM domain does not make extensive contacts with 5'SL RNA. We propose a model in which the initial recognition of 5'SL by LARP6 is mediated by the RNK epitope and further stabilized by the RRM domain. This discovery suggests that the interaction between LARP6 and collagen mRNAs can be blocked by small molecules that target the RNK epitope and will help rational design of the LARP6 binding inhibitors as specific antifibrotic drugs.
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Affiliation(s)
- Lela Stefanovic
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA
| | - Blaine H Gordon
- Department of Chemistry and Biochemistry, College of Arts and Sciences, Florida State University, Tallahassee, FL 32306, USA; Institute of Molecular Biophysics, College of Arts and Sciences, Florida State University, Tallahassee, FL 32306, USA
| | - Robert Silvers
- Department of Chemistry and Biochemistry, College of Arts and Sciences, Florida State University, Tallahassee, FL 32306, USA; Institute of Molecular Biophysics, College of Arts and Sciences, Florida State University, Tallahassee, FL 32306, USA
| | - Branko Stefanovic
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA.
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Hau HTA, Ogundele O, Hibbert AH, Monfries CAL, Exelby K, Wood NJ, Nevarez-Mejia J, Carbajal MA, Fleck RA, Dermit M, Mardakheh FK, Williams-Ward VC, Pipalia TG, Conte MR, Hughes SM. Maternal Larp6 controls oocyte development, chorion formation and elevation. Development 2020; 147:dev187385. [PMID: 32054660 PMCID: PMC7055395 DOI: 10.1242/dev.187385] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 01/23/2020] [Indexed: 12/19/2022]
Abstract
La-related protein 6 (Larp6) is a conserved RNA-binding protein found across eukaryotes that has been suggested to regulate collagen biogenesis, muscle development, ciliogenesis, and various aspects of cell proliferation and migration. Zebrafish have two Larp6 family genes: larp6a and larp6b Viable and fertile single and double homozygous larp6a and larp6b zygotic mutants revealed no defects in muscle structure, and were indistinguishable from heterozygous or wild-type siblings. However, larp6a mutant females produced eggs with chorions that failed to elevate fully and were fragile. Eggs from larp6b single mutant females showed minor chorion defects, but chorions from eggs laid by larp6a;larp6b double mutant females were more defective than those from larp6a single mutants. Electron microscopy revealed defective chorionogenesis during oocyte development. Despite this, maternal zygotic single and double mutants were viable and fertile. Mass spectrometry analysis provided a description of chorion protein composition and revealed significant reductions in a subset of zona pellucida and lectin-type proteins between wild-type and mutant chorions that paralleled the severity of the phenotype. We conclude that Larp6 proteins are required for normal oocyte development, chorion formation and egg activation.
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Affiliation(s)
- Hoi Ting A Hau
- Randall Centre for Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Oluwaseun Ogundele
- Randall Centre for Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Andrew H Hibbert
- Randall Centre for Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Clinton A L Monfries
- Randall Centre for Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Katherine Exelby
- Randall Centre for Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Natalie J Wood
- Randall Centre for Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Jessica Nevarez-Mejia
- Randall Centre for Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | | | - Roland A Fleck
- Centre for Ultrastructural Imaging, King's College London, London SE1 1UL, UK
| | - Maria Dermit
- Barts Cancer Institute, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Faraz K Mardakheh
- Barts Cancer Institute, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Victoria C Williams-Ward
- Randall Centre for Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Tapan G Pipalia
- Randall Centre for Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Maria R Conte
- Randall Centre for Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Simon M Hughes
- Randall Centre for Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
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Dock-Bregeon AC, Lewis KA, Conte MR. The La-related proteins: structures and interactions of a versatile superfamily of RNA-binding proteins. RNA Biol 2019; 18:178-193. [PMID: 31752575 DOI: 10.1080/15476286.2019.1695712] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The La-related proteins (LaRPs) are an ancient superfamily of RNA-binding proteins orchestrating the major fates of RNA, from processing and maturation to regulation of mRNA translation. LaRPs are instrumental in modulating complex assemblies where the RNA is bound, folded, processed, escorted and presented to the functional effectors often through recruitment of protein partners. This intricate web of protein-RNA and protein-protein interactions is enabled by the modular nature of the LaRPs, comprising several structured domains connected by flexible linkers, and other sequences lacking recognizable folded motifs. Recent structures, together with biochemical and biophysical studies, have provided insights into how each LaRP family has evolved unique mechanisms of RNA recognition, not only through the conserved RNA-binding unit, the La-module, but also mediated by other family-specific motifs. Furthermore, in a series of unexpected twists and turns, they have revealed that the dynamic and conformational interplay of multi-structured domains and disordered regions operate in unison to achieve RNA substrate discrimination. This review proposes a perspective of our current knowledge of the structure-function relationship of the LaRP superfamily.
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Affiliation(s)
| | - Karen A Lewis
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX, USA
| | - Maria R Conte
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, UK
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