title: The Lamin B receptor is essential for cholesterol synthesis and perturbed by disease-causing mutations.
abstract: Lamin B receptor (LBR) is a polytopic membrane protein residing in the inner nuclear membrane in association with the nuclear lamina. We demonstrate that human LBR is essential for cholesterol synthesis. LBR mutant derivatives implicated in Greenberg skeletal dysplasia or Pelger-Huët anomaly fail to rescue the cholesterol auxotrophy of a LBR-deficient human cell line, consistent with a loss-of-function mechanism for these congenital disorders. These disease-causing variants fall into two classes: point mutations in the sterol reductase domain perturb enzymatic activity by reducing the affinity for the essential cofactor NADPH, while LBR truncations render the mutant protein metabolically unstable, leading to its rapid degradation at the inner nuclear membrane. Thus, metabolically unstable LBR variants may serve as long-sought-after model substrates enabling previously impossible investigations of poorly understood protein turnover mechanisms at the inner nuclear membrane of higher eukaryotes.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States.
authors.forename: Pei-Ling
authors.initials: PL
authors.lastname: Tsai
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States.
authors.forename: Chenguang
authors.initials: C
authors.lastname: Zhao
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Turner
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States.|Department of Cell Biology, Yale School of Medicine, New Haven, United States.
authors.forename: Christian
authors.identifier: 0000-0002-1237-4267
authors.initials: C
authors.lastname: Schlieker
mesh_terms: D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D006801:Humans; D009154:Mutation; D010009:Osteochondrodysplasias / Q000503:physiopathology; D010381:Pelger-Huet Anomaly / Q000503:physiopathology; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics* / Q000378:metabolism*; D000097682:Lamin B Receptor
chemical_list: D002784:Cholesterol; D018160:Receptors, Cytoplasmic and Nuclear; D000097682:Lamin B Receptor
keywords: ER-associated degradation (ERAD); biochemistry; cell biology; cholesterol metabolism; human; inner nuclear membrane; nuclear lamina; protein quality control