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Hayashi T, Kubota T, Mariko I, Takamoto I, Aihara M, Sakurai Y, Wada N, Miki T, Yamauchi T, Kubota N, Kadowaki T. Lack of Brain Insulin Receptor Substrate-1 Causes Growth Retardation, With Decreased Expression of Growth Hormone-Releasing Hormone in the Hypothalamus. Diabetes 2021; 70:1640-1653. [PMID: 33980693 DOI: 10.2337/db20-0482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 05/07/2021] [Indexed: 11/13/2022]
Abstract
Insulin receptor substrate-1 (Irs1) is one of the major substrates for insulin receptor and insulin-like growth factor-1 (IGF-1) receptor tyrosine kinases. Systemic Irs1-deficient mice show growth retardation, with resistance to insulin and IGF-1, although the underlying mechanisms remain poorly understood. For this study, we generated mice with brain-specific deletion of Irs1 (NIrs1KO mice). The NIrs1KO mice exhibited lower body weights, shorter bodies and bone lengths, and decreased bone density. Moreover, the NIrs1KO mice exhibited increased insulin sensitivity and glucose utilization in the skeletal muscle. Although the ability of the pituitary to secrete growth hormone (GH) remained intact, the amount of hypothalamic growth hormone-releasing hormone (GHRH) was significantly decreased and, accordingly, the pituitary GH mRNA expression levels were impaired in these mice. Plasma GH and IGF-1 levels were also lower in the NIrs1KO mice. The expression levels of GHRH protein in the median eminence, where Irs1 antibody staining is observed, were markedly decreased in the NIrs1KO mice. In vitro, neurite elongation after IGF-1 stimulation was significantly impaired by Irs1 downregulation in the cultured N-38 hypothalamic neurons. In conclusion, brain Irs1 plays important roles in the regulation of neurite outgrowth of GHRH neurons, somatic growth, and glucose homeostasis.
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Affiliation(s)
- Takanori Hayashi
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Clinical Nutrition, National Institute of Health and Nutrition, National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Tokyo, Japan
| | - Tetsuya Kubota
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Clinical Nutrition, National Institute of Health and Nutrition, National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Tokyo, Japan
- Laboratory for Intestinal Ecosystem, RIKEN Center for Integrative Medical Sciences, Kanagawa, Japan
- Division of Diabetes and Metabolism, The Institute of Medical Science, Asahi Life Foundation, Tokyo, Japan
- Division of Cardiovascular Medicine, Toho University, Ohashi Hospital, Tokyo, Japan
| | - Inoue Mariko
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Clinical Nutrition, National Institute of Health and Nutrition, National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Tokyo, Japan
| | - Iseki Takamoto
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Masakazu Aihara
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yoshitaka Sakurai
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Nobuhiro Wada
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Clinical Nutrition, National Institute of Health and Nutrition, National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Tokyo, Japan
| | - Takashi Miki
- Department of Medical Physiology, Chiba University, Graduate School of Medicine, Chiba, Japan
| | - Toshimasa Yamauchi
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Naoto Kubota
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Clinical Nutrition, National Institute of Health and Nutrition, National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Tokyo, Japan
- Department of Clinical Nutrition Therapy, The University of Tokyo, Tokyo, Japan
| | - Takashi Kadowaki
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Prevention of Diabetes and Lifestyle-Related Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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