title: Dominant protein interactions that influence the pathogenesis of conformational diseases.
abstract: Misfolding of exportable proteins can trigger endocrinopathies. For example, misfolding of insulin can result in autosomal dominant mutant INS gene-induced diabetes of youth, and misfolding of thyroglobulin can result in autosomal recessive congenital hypothyroidism with deficient thyroglobulin. Both proinsulin and thyroglobulin normally form homodimers; the mutant versions of both proteins misfold in the ER, triggering ER stress, and, in both cases, heterozygosity creates potential for cross-dimerization between mutant and WT gene products. Here, we investigated these two ER-retained mutant secretory proteins and the selectivity of their interactions with their respective WT counterparts. In both cases and in animal models of these diseases, we found that conditions favoring an increased stoichiometry of mutant gene product dominantly inhibited export of the WT partner, while increased relative level of the WT gene product helped to rescue secretion of the mutant partner. Surprisingly, the bidirectional consequences of secretory blockade and rescue occur simultaneously in the same cells. Thus, in the context of heterozygosity, expression level and stability of WT subunits may be a critical factor influencing the effect of protein misfolding on clinical phenotype. These results offer new insight into dominant as well as recessive inheritance of conformational diseases and offer opportunities for the development of new therapies.
authors.affiliation: Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan, USA.
authors.forename: Jordan
authors.initials: J
authors.lastname: Wright
authors.forename: Xiaofan
authors.initials: X
authors.lastname: Wang
authors.forename: Leena
authors.initials: L
authors.lastname: Haataja
authors.forename: Aaron P
authors.initials: AP
authors.lastname: Kellogg
authors.forename: Jaemin
authors.initials: J
authors.lastname: Lee
authors.forename: Ming
authors.initials: M
authors.lastname: Liu
authors.forename: Peter
authors.initials: P
authors.lastname: Arvan
mesh_terms: D000818:Animals; D003409:Congenital Hypothyroidism / Q000235:genetics / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D050505:Mutant Proteins / Q000378:metabolism; D020125:Mutation, Missense; D011384:Proinsulin / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization; D057165:Proteostasis Deficiencies / Q000235:genetics / Q000378:metabolism*; D013954:Thyroglobulin / Q000235:genetics / Q000378:metabolism*
chemical_list: D050505:Mutant Proteins; D013954:Thyroglobulin; D011384:Proinsulin