title: The Human 343delT HSPB5 Chaperone Associated with Early-onset Skeletal Myopathy Causes Defects in Protein Solubility.
abstract: Mutations of HSPB5 (also known as CRYAB or αB-crystallin), a bona fide heat shock protein and molecular chaperone encoded by the HSPB5 (crystallin, alpha B) gene, are linked to multisystem disorders featuring variable combinations of cataracts, cardiomyopathy, and skeletal myopathy. This study aimed to investigate the pathological mechanisms involved in an early-onset myofibrillar myopathy manifesting in a child harboring a homozygous recessive mutation in HSPB5, 343delT. To study HSPB5 343delT protein dynamics, we utilize model cell culture systems including induced pluripotent stem cells derived from the 343delT patient (343delT/343delT) along with isogenic, heterozygous, gene-corrected control cells (WT KI/343delT) and BHK21 cells, a cell line lacking endogenous HSPB5 expression. 343delT/343delT and WT KI/343delT-induced pluripotent stem cell-derived skeletal myotubes and cardiomyocytes did not express detectable levels of 343delT protein, contributable to the extreme insolubility of the mutant protein. Overexpression of HSPB5 343delT resulted in insoluble mutant protein aggregates and induction of a cellular stress response. Co-expression of 343delT with WT prevented visible aggregation of 343delT and improved its solubility. Additionally, in vitro refolding of 343delT in the presence of WT rescued its solubility. We demonstrate an interaction between WT and 343delT both in vitro and within cells. These data support a loss-of-function model for the myopathy observed in the patient because the insoluble mutant would be unavailable to perform normal functions of HSPB5, although additional gain-of-function effects of the mutant protein cannot be excluded. Additionally, our data highlight the solubilization of 343delT by WT, concordant with the recessive inheritance of the disease and absence of symptoms in carrier individuals.
authors.affiliation: From the Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112-5650.
authors.forename: Katie A
authors.initials: KA
authors.lastname: Mitzelfelt
authors.affiliation: Arcturus Therapeutics, San Diego, California 92121.
authors.forename: Pattraranee
authors.initials: P
authors.lastname: Limphong
authors.affiliation: the Cardiovascular Center.
authors.forename: Melinda J
authors.initials: MJ
authors.lastname: Choi
authors.affiliation: the Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom.
authors.forename: Frances D L
authors.initials: FD
authors.lastname: Kondrat
authors.affiliation: the Cardiovascular Center.
authors.forename: Shuping
authors.initials: S
authors.lastname: Lai
authors.affiliation: the Cardiovascular Center.
authors.forename: Kurt D
authors.initials: KD
authors.lastname: Kolander
authors.affiliation: Departments of Anesthesiology and Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Wai-Meng
authors.initials: WM
authors.lastname: Kwok
authors.affiliation: the Cardiovascular Center.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Dai
authors.affiliation: the Cardiovascular Center.
authors.forename: Michael N
authors.initials: MN
authors.lastname: Grzybowski
authors.affiliation: the Department of Pathophysiology, Xiangya School of Medicine, Central South University, Changsha City, Hunan 410078, China.
authors.forename: Huali
authors.initials: H
authors.lastname: Zhang
authors.affiliation: the Division of Cardiology, Department of Medicine, University of Utah, Salt Lake City, Utah 84132.
authors.forename: Graydon M
authors.initials: GM
authors.lastname: Taylor
authors.affiliation: the Division of Cardiology, Department of Medicine, University of Utah, Salt Lake City, Utah 84132.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Lui
authors.affiliation: the Cardiovascular Center.
authors.forename: Mai T
authors.initials: MT
authors.lastname: Thao
authors.affiliation: the Northern Genetics Service, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 3BZ, United Kingdom.
authors.forename: Judith A
authors.initials: JA
authors.lastname: Hudson
authors.affiliation: the National Health Service England Health Science Services for Rare Neuromuscular Diseases, Muscle Immunoanalysis Unit, Dental Hospital, Richardson Road, Newcastle upon Tyne NE2 4AZ, United Kingdom.
authors.forename: Rita
authors.initials: R
authors.lastname: Barresi
authors.affiliation: Neuromuscular Genetics, Newcastle University John Walton Centre for Muscular Dystrophy Research, Medical Research Council Centre for Neuromuscular Diseases, Institute of Genetic Medicine, International Centre for Life, Newcastle upon Tyne NE1 3BZ, United Kingdom.
authors.forename: Kate
authors.initials: K
authors.lastname: Bushby
authors.affiliation: the Department of Paediatric Neurology, Neuromuscular Service Evelina Children's Hospital, Guy's and St. Thomas' National Health Service Foundation Trust, London SE1 7EH, United Kingdom, the Randall Division of Cell and Molecular Biophysics, Muscle Signalling Section, King's College London, London SE1 1UL, United Kingdom, the Department of Basic and Clinical Neuroscience Institute of Psychiatry, Psychology and Neuroscience, King's College London SE5 9RX, United Kingdom.
authors.forename: Heinz
authors.initials: H
authors.lastname: Jungbluth
authors.affiliation: the Department of Paediatric Neurology, Neuromuscular Service Evelina Children's Hospital, Guy's and St. Thomas' National Health Service Foundation Trust, London SE1 7EH, United Kingdom.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Wraige
authors.affiliation: the Cardiovascular Center.
authors.forename: Aron M
authors.initials: AM
authors.lastname: Geurts
authors.affiliation: the Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom.
authors.forename: Justin L P
authors.initials: JL
authors.lastname: Benesch
authors.affiliation: PharmaCell, Maastricht, Netherlands, 6229 EV Maastricht.
authors.forename: Michael
authors.initials: M
authors.lastname: Riedel
authors.affiliation: the Sorbonne Universités, University Pierre and Marie Curie, Univ Paris 06, CNRS, Laboratoire de Biologie du Dévelopment de Villefranche sur mer (LBDV), UMR 7009, 181 Chemin du Lazaret, 06230 Villefranche sur mer, France, and.
authors.forename: Elisabeth S
authors.initials: ES
authors.lastname: Christians
authors.affiliation: the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Alex C
authors.initials: AC
authors.lastname: Minella
authors.affiliation: From the Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112-5650, the Cardiovascular Center, ibenjamin@mcw.edu.
authors.forename: Ivor J
authors.initials: IJ
authors.lastname: Benjamin
mesh_terms: D009202:Cardiomyopathies / Q000209:etiology / Q000235:genetics* / Q000378:metabolism*; D002386:Cataract / Q000209:etiology / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D006720:Homozygote; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000378:metabolism; D008297:Male; D008954:Models, Biological; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D009135:Muscular Diseases / Q000209:etiology / Q000235:genetics* / Q000378:metabolism*; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism; D010375:Pedigree; D066263:Protein Aggregation, Pathological / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D012995:Solubility; D038203:alpha-Crystallin B Chain / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: C059215:CRYAB protein, human; D050505:Mutant Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D038203:alpha-Crystallin B Chain
keywords: HSPB5 (CRYAB, αB-crystallin); aggregation; chaperone; induced pluripotent stem cell (iPSC); myofibrillar myopathy; protein misfolding; small heat shock protein (sHsp)