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Ataie-Ashtiani S, Forbes B. A Review of the Biosynthesis and Structural Implications of Insulin Gene Mutations Linked to Human Disease. Cells 2023; 12:cells12071008. [PMID: 37048081 PMCID: PMC10093311 DOI: 10.3390/cells12071008] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/13/2023] [Accepted: 03/15/2023] [Indexed: 03/29/2023] Open
Abstract
The discovery of the insulin hormone over 100 years ago, and its subsequent therapeutic application, marked a key landmark in the history of medicine and medical research. The many roles insulin plays in cell metabolism and growth have been revealed by extensive investigations into the structure and function of insulin, the insulin tyrosine kinase receptor (IR), as well as the signalling cascades, which occur upon insulin binding to the IR. In this review, the insulin gene mutations identified as causing disease and the structural implications of these mutations will be discussed. Over 100 studies were evaluated by one reviewing author, and over 70 insulin gene mutations were identified. Mutations may impair insulin gene transcription and translation, preproinsulin trafficking and proinsulin sorting, or insulin-IR interactions. A better understanding of insulin gene mutations and the resultant pathophysiology can give essential insight into the molecular mechanisms underlying impaired insulin biosynthesis and insulin-IR interaction.
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Schlegel A, Petersen WC, Holbrook AA, Iverson LK, Graham TE. A Novel INS Mutation in the C-Peptide Region Causing Hyperproinsulinemic Maturity Onset Diabetes of Youth Type 10. Lab Med 2022; 54:327-332. [PMID: 36242597 DOI: 10.1093/labmed/lmac115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Abstract
Monogenetic diabetes mellitus (DM) describes a collection of single-gene diseases marked by hyperglycemia presenting in childhood or adulthood and the absence of immunological markers of type 1 DM. Mutations in the human insulin gene INS give rise to two separate clinical syndromes: permanent neonatal DM, type 4 (PNDM4), and maturity-onset diabetes of youth, type 10 (MODY10); the former presents shortly after birth and the latter presents in childhood and adulthood. We describe a 40-year-old man in a kindred with high prevalence of DM who presented with severe hyperglycemia but not ketoacidosis or hypertriglyceridemia. Twelve years after initial presentation, the patient had elevated proinsulin and normal plasma C-peptide when nearly euglycemic on treatment with insulin glargine. A novel INS mutation, Gln65Arg, within the C-peptide region was identified. The INS (p.Gln65Arg) mutation may cause MODY10 by disrupting proinsulin maturation.
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Affiliation(s)
- Amnon Schlegel
- Diabetes and Endocrine Treatment Specialists , Sandy, UT , USA
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Dhayalan B, Glidden MD, Zaykov AN, Chen YS, Yang Y, Phillips NB, Ismail-Beigi F, Jarosinski MA, DiMarchi RD, Weiss MA. Peptide Model of the Mutant Proinsulin Syndrome. I. Design and Clinical Correlation. Front Endocrinol (Lausanne) 2022; 13:821069. [PMID: 35299972 PMCID: PMC8922534 DOI: 10.3389/fendo.2022.821069] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 01/17/2022] [Indexed: 12/16/2022] Open
Abstract
The mutant proinsulin syndrome is a monogenic cause of diabetes mellitus due to toxic misfolding of insulin's biosynthetic precursor. Also designated mutant INS-gene induced diabetes of the young (MIDY), this syndrome defines molecular determinants of foldability in the endoplasmic reticulum (ER) of β-cells. Here, we describe a peptide model of a key proinsulin folding intermediate and variants containing representative clinical mutations; the latter perturb invariant core sites in native proinsulin (LeuB15→Pro, LeuA16→Pro, and PheB24→Ser). The studies exploited a 49-residue single-chain synthetic precursor (designated DesDi), previously shown to optimize in vitro efficiency of disulfide pairing. Parent and variant peptides contain a single disulfide bridge (cystine B19-A20) to provide a model of proinsulin's first oxidative folding intermediate. The peptides were characterized by circular dichroism and redox stability in relation to effects of the mutations on (a) in vitro foldability of the corresponding insulin analogs and (b) ER stress induced in cell culture on expression of the corresponding variant proinsulins. Striking correlations were observed between peptide biophysical properties, degree of ER stress and age of diabetes onset (neonatal or adolescent). Our findings suggest that age of onset reflects the extent to which nascent structure is destabilized in proinsulin's putative folding nucleus. We envisage that such peptide models will enable high-resolution structural studies of key folding determinants and in turn permit molecular dissection of phenotype-genotype relationships in this monogenic diabetes syndrome. Our companion study (next article in this issue) employs two-dimensional heteronuclear NMR spectroscopy to define site-specific perturbations in the variant peptides.
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Affiliation(s)
- Balamurugan Dhayalan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Michael D. Glidden
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH, United States
- Department of Physiology & Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, United States
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | | | - Yen-Shan Chen
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Yanwu Yang
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Nelson B. Phillips
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Faramarz Ismail-Beigi
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH, United States
- Department of Physiology & Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, United States
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Mark A. Jarosinski
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
| | | | - Michael A. Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
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Dhayalan B, Weiss MA. Diabetes-Associated Mutations in Proinsulin Provide a "Molecular Rheostat" of Nascent Foldability. Curr Diab Rep 2022; 22:85-94. [PMID: 35119630 DOI: 10.1007/s11892-022-01447-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/04/2022] [Indexed: 11/28/2022]
Abstract
PURPOSE OF REVIEW Diabetes mellitus (DM) due to toxic misfolding of proinsulin variants provides a monogenic model of endoplasmic reticulum (ER) stress. The mutant proinsulin syndrome (also designated MIDY; Mutant INS-gene-induced Diabetes of Youth or Maturity-onset diabetes of the young 10 (MODY10)) ordinarily presents as permanent neonatal-onset DM, but specific amino-acid substitutions may also present later in childhood or adolescence. This review highlights structural mechanisms of proinsulin folding as inferred from phenotype-genotype relationships. RECENT FINDINGS MIDY mutations most commonly add or remove a cysteine, leading to a variant polypeptide containing an odd number of thiol groups. Such variants are associated with aberrant intermolecular disulfide pairing, ER stress, and neonatal β-cell dysfunction. Non-cysteine-related (NCR) mutations (occurring in both the B and A domains of proinsulin) define distinct determinants of foldability and vary in severity. The range of ages of onset, therefore, reflects a "molecular rheostat" connecting protein biophysics to quality-control ER checkpoints. Because in most mammalian cell lines even wild-type proinsulin exhibits limited folding efficiency, molecular barriers to folding uncovered by NCR MIDY mutations may pertain to β-cell dysfunction in non-syndromic type 2 DM due to INS-gene overexpression in the face of peripheral insulin resistance. Recent studies of MIDY mutations and related NCR variants, combining molecular and cell-based approaches, suggest that proinsulin has evolved at the edge of non-foldability. Chemical protein synthesis promises to enable comparative studies of "non-foldable" proinsulin variants to define key steps in wild-type biosynthesis. Such studies may create opportunities for novel therapeutic approaches to non-syndromic type 2 DM.
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Affiliation(s)
- Balamurugan Dhayalan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Michael A Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA.
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, 47907, USA.
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Yang Y, Shu H, Hu J, Li L, Wang J, Chen T, Zhen J, Sun J, Feng W, Xiong Y, Huang Y, Li X, Zhang K, Fan Z, Guo H, Liu M. A Novel Nonsense INS Mutation Causes Inefficient Preproinsulin Translocation Into the Endoplasmic Reticulum. Front Endocrinol (Lausanne) 2021; 12:774634. [PMID: 35069438 PMCID: PMC8769375 DOI: 10.3389/fendo.2021.774634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 12/06/2021] [Indexed: 11/13/2022] Open
Abstract
Preproinsulin (PPI) translocation across the membrane of the endoplasmic reticulum (ER) is the first and critical step of insulin biosynthesis. Inefficient PPI translocation caused by signal peptide (SP) mutations can lead to β-cell failure and diabetes. However, the effect of proinsulin domain on the efficiency of PPI translocation remains unknown. With whole exome sequencing, we identified a novel INS nonsense mutation resulting in an early termination at the 46th residue of PPI (PPI-R46X) in two unrelated patients with early-onset diabetes. We examined biological behaviors of the mutant and compared them to that of an established neonatal diabetes causing mutant PPI-C96Y. Although both mutants were retained in the cells, unlike C96Y, R46X did not induce ER stress or form abnormal disulfide-linked proinsulin complexes. More importantly, R46X did not interact with co-expressed wild-type (WT) proinsulin in the ER, and did not impair proinsulin-WT folding, trafficking, and insulin production. Metabolic labeling experiments established that, despite with an intact SP, R46X failed to be efficiently translocated into the ER, suggesting that proinsulin domain downstream of SP plays an important unrecognized role in PPI translocation across the ER membrane. The study not only expends the list of INS mutations associated with diabetes, but also provides genetic and biological evidence underlying the regulation mechanism of PPI translocation.
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Affiliation(s)
- Ying Yang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Hua Shu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Jingxin Hu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Lei Li
- Department of Endocrinology, The Second Part of Jilin University First Hospital, Jilin, China
| | - Jianyu Wang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Tingting Chen
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Jinyang Zhen
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Jinhong Sun
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Wenli Feng
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Yi Xiong
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Yumeng Huang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Xin Li
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Kai Zhang
- Department of Technology Services, RSR Tianjin Biotech Co., Tianjin, China
| | - Zhenqian Fan
- Department of Endocrinology and Metabolism, The Second Hospital of Tianjin Medical University, Tianjin, China
- *Correspondence: Ming Liu, ; Zhenqian Fan, ; Hui Guo,
| | - Hui Guo
- Department of Endocrinology, The Second Part of Jilin University First Hospital, Jilin, China
- *Correspondence: Ming Liu, ; Zhenqian Fan, ; Hui Guo,
| | - Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
- *Correspondence: Ming Liu, ; Zhenqian Fan, ; Hui Guo,
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