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Sasako T. Exploring mechanisms of insulin action and strategies to treat diabetes. Endocr J 2024; 71:651-660. [PMID: 38811207 DOI: 10.1507/endocrj.ej24-0003] [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] [Indexed: 05/31/2024] Open
Abstract
Insulin is a hormone that positively regulates anabolism and cell growth, whereas diabetes mellitus is a disease characterized by hyperglycemia associated with impaired insulin action. My colleagues and I have elucidated multifaceted insulin action in various tissues mainly by means of model mice. In the liver, insulin regulates endoplasmic reticulum (ER) stress response during feeding, whereas ER stress 'response failure' contributes to the development of steatohepatitis comorbid with diabetes. Not only the liver but also the proximal tubules of the kidney are important in the regulation of gluconeogenesis, and we revealed that insulin suppresses gluconeogenesis in accordance with absorbed glucose in the latter tissue. In skeletal muscle, another important insulin-targeted tissue, impaired insulin/IGF-1 signaling leads not only to sarcopenia, an aging-related disease of skeletal muscle, but also to osteopenia and shorter longevity. Aging is regulated by adipokines as well, and it should be considered that aging could be accelerated by 'imbalanced adipokines' in patients with a genetic background of progeria. Moreover, we reported the effects of intensive multifactorial intervention on diabetic vascular complications and mortality in patients with type 2 diabetes in a large-scale clinical trial, the J-DOIT3, and the results of subsequent sub-analyses of renal events and fracture events. Various approaches of research enable us of endocrinologists to elucidate the physiology of hormone signaling, the mechanisms underlying the development of endocrine diseases, and the appropriate treatment measures. These approaches also raise fundamental questions, but addressing them in an appropriate manner will surely contribute to the further development of endocrinology.
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Affiliation(s)
- Takayoshi Sasako
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
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Sasako T. Exploring mechanisms underlying diabetes comorbidities and strategies to prevent vascular complications. Diabetol Int 2024; 15:34-40. [PMID: 38264227 PMCID: PMC10800323 DOI: 10.1007/s13340-023-00677-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 11/15/2023] [Indexed: 01/25/2024]
Abstract
It is important to prevent not only diabetic complications but also diabetic comorbidities in diabetes care. We have elucidated multifaceted insulin action in various tissues mainly by means of model mice, and it was revealed that insulin regulates endoplasmic reticulum (ER) stress response during feeding, whereas ER stress 'response failure' contributes to the development of steatohepatitis, one of the major diabetic comorbidities. Insulin regulates gluconeogenesis not only in the liver but also in the proximal tubules of the kidney, which is also suppressed by reabsorbed glucose in the latter. In skeletal muscle, another important insulin-targeted tissue, impaired insulin/IGF-1 signaling leads not only to sarcopenia, an aging-related disease, but also to bone loss and shorter longevity. Aging is regulated by adipokines as well, and it is deemed to be accelerated by 'imbalanced adipokines' in combination with genetic background of progeria. Moreover, we reported effects of intensive multifactorial intervention on diabetic complications and mortality in patients with type 2 diabetes in a large-scale clinical trial, the J-DOIT3, followed by reports of subsequent sub-analyses of renal events and fracture events. Various approaches to elucidate the mechanisms underlying the development of diabetes and how it should be treated are expected to help us improve diabetes management.
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Affiliation(s)
- Takayoshi Sasako
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo, 113-0033 Japan
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Sasako T, Kadowaki H, Fujiwara T, Kodera S, Komuro I, Kadowaki T, Yamauchi T. Severe aortic stenosis during leptin replacement therapy in a patient with generalized lipodystrophy-associated progeroid syndrome due to a LMNA variant: a case report. J Diabetes Investig 2022; 13:1636-1638. [PMID: 35524481 PMCID: PMC9434571 DOI: 10.1111/jdi.13827] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 03/28/2022] [Accepted: 05/01/2022] [Indexed: 11/28/2022] Open
Abstract
Leptin replacement therapy (LRT) has drastically improved the prognosis of patients with lipodystrophy, but pro‐inflammatory properties of leptin could become evident in the long term. Here, we report a 30‐year‐old Japanese woman with generalized lipodystrophy‐associated progeroid syndrome due to a heterozygous LMNA variant (c.29C > T; p.T10I), who was diagnosed with severe aortic stenosis (AS) after more than a decade of LRT, which required transcatheter aortic valve implantation. Given her marked hypoadiponectinemia and the LMNA variant, our patient might have been susceptible to progeria‐associated disorders, including aortic stenosis, which could have been exaggerated by the prolonged ‘imbalanced adipokines’ caused by LRT between pro‐inflammatory leptin and anti‐inflammatory adiponectin. Thus, long‐term LRT could be associated with AS in patients with the LMNA variant to cause generalized lipodystrophy‐associated progeroid syndrome and hypoadiponectinemia.
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Affiliation(s)
- Takayoshi Sasako
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | | | - Takayuki Fujiwara
- Department of Cardiovascular Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Satoshi Kodera
- Department of Cardiovascular Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Issei Komuro
- Department of Cardiovascular Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | | | - Toshimasa Yamauchi
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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Hosoe J, Kawashima-Sonoyama Y, Miya F, Kadowaki H, Suzuki K, Kato T, Matsuzawa F, Aikawa SI, Okada Y, Tsunoda T, Hanaki K, Kanzaki S, Shojima N, Yamauchi T, Kadowaki T. Genotype-Structure-Phenotype Correlations of Disease-Associated IGF1R Variants and Similarities to Those of INSR Variants. Diabetes 2021; 70:1874-1884. [PMID: 34074726 DOI: 10.2337/db20-1145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 05/10/2021] [Indexed: 11/13/2022]
Abstract
We previously reported genotype-phenotype correlations in 12 missense variants causing severe insulin resistance, located in the second and third fibronectin type III (FnIII) domains of the insulin receptor (INSR), containing the α-β cleavage and part of insulin-binding sites. This study aimed to identify genotype-phenotype correlations in FnIII domain variants of IGF1R, a structurally related homolog of INSR, which may be associated with growth retardation, using the recently reported crystal structures of IGF1R. A structural bioinformatics analysis of five previously reported disease-associated heterozygous missense variants and a likely benign variant in the FnIII domains of IGF1R predicted that the disease-associated variants would severely impair the hydrophobic core formation and stability of the FnIII domains or affect the α-β cleavage site, while the likely benign variant would not affect the folding of the domains. A functional analysis of these variants in CHO cells showed impaired receptor processing and autophosphorylation in cells expressing the disease-associated variants but not in those expressing the wild-type form or the likely benign variant. These results demonstrated genotype-phenotype correlations in the FnIII domain variants of IGF1R, which are presumably consistent with those of INSR and would help in the early diagnosis of patients with disease-associated IGF1R variants.
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Affiliation(s)
- Jun Hosoe
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yuki Kawashima-Sonoyama
- Division of Pediatrics and Perinatology, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Fuyuki Miya
- Department of Medical Science Mathematics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
- Laboratory for Medical Science Mathematics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
- CREST, Japan Science and Technology Agency, Tokyo
| | | | - Ken Suzuki
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Statistical Genetics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Takashi Kato
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | | | | | - Yukinori Okada
- Department of Statistical Genetics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Tatsuhiko Tsunoda
- Department of Medical Science Mathematics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
- Laboratory for Medical Science Mathematics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
- CREST, Japan Science and Technology Agency, Tokyo
- Laboratory for Medical Science Mathematics, Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Keiichi Hanaki
- School of Health Science, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Susumu Kanzaki
- Asahigawaso Rehabilitation and Medical Center, Okayama, Japan
| | - Nobuhiro Shojima
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Toshimasa Yamauchi
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Takashi Kadowaki
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Toranomon Hospital, Tokyo, Japan
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