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Diversity of Structural, Dynamic, and Environmental Effects Explain a Distinctive Functional Role of Transmembrane Domains in the Insulin Receptor Subfamily. Int J Mol Sci 2023; 24:ijms24043906. [PMID: 36835322 PMCID: PMC9965288 DOI: 10.3390/ijms24043906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/04/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
Human InsR, IGF1R, and IRR receptor tyrosine kinases (RTK) of the insulin receptor subfamily play an important role in signaling pathways for a wide range of physiological processes and are directly associated with many pathologies, including neurodegenerative diseases. The disulfide-linked dimeric structure of these receptors is unique among RTKs. Sharing high sequence and structure homology, the receptors differ dramatically in their localization, expression, and functions. In this work, using high-resolution NMR spectroscopy supported by atomistic computer modeling, conformational variability of the transmembrane domains and their interactions with surrounding lipids were found to differ significantly between representatives of the subfamily. Therefore, we suggest that the heterogeneous and highly dynamic membrane environment should be taken into account in the observed diversity of the structural/dynamic organization and mechanisms of activation of InsR, IGF1R, and IRR receptors. This membrane-mediated control of receptor signaling offers an attractive prospect for the development of new targeted therapies for diseases associated with dysfunction of insulin subfamily receptors.
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Miller MR, McDermitt DJ, Sauvanet C, Lombardo AJ, Zaman R, Bretscher A. The RabGAPs EPI64A and EPI64B regulate the apical structure of epithelial cells †. Mol Biol Cell 2021; 33:ar8. [PMID: 34757852 PMCID: PMC8886810 DOI: 10.1091/mbc.e21-05-0268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Here we report on the related TBC/RabGAPs EPI64A and EPI64B and show that they function to organize the apical aspect of epithelial cells. EPI64A binds the scaffolding protein EBP50/NHERF1, which itself binds active ezrin in epithelial cell microvilli. Epithelial cells additionally express EPI64B that also localizes to microvilli. However, EPI64B does not bind EBP50 and both proteins are shown to have a microvillar localization domain that spans the RabGAP domains. CRISPR/Cas9 was used to inactivate expression of each protein individually or both in Jeg-3 and Caco2 cells. In Jeg-3 cells, loss of EPI64B resulted in a reduction of apical microvilli, and a further reduction was seen in the double knockout, mostly likely due to misregulation of Rab8 and Rab35. In addition, apical junctions were partially disrupted in cells lacking EPI64A and accentuated in the double knockout. In Caco2 loss of EPI64B resulted in wavy junctions, whereas loss of both EPI64A and EPI64B had a severe phenotype often resulting in cells with a stellate apical morphology. In the knockout cells, the basal region of the cell remained unchanged, so EPI64A and EPI64B specifically localize to and regulate the morphology of the apical domain of polarized epithelial cells.
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Affiliation(s)
- Matthew R Miller
- Weill Institute for Cell and Molecular Biology, Department of Molecular Biology and Genetics, Cornell University, Ithaca NY 14850
| | - David J McDermitt
- Weill Institute for Cell and Molecular Biology, Department of Molecular Biology and Genetics, Cornell University, Ithaca NY 14850
| | - Cecile Sauvanet
- Weill Institute for Cell and Molecular Biology, Department of Molecular Biology and Genetics, Cornell University, Ithaca NY 14850
| | - Andrew J Lombardo
- Weill Institute for Cell and Molecular Biology, Department of Molecular Biology and Genetics, Cornell University, Ithaca NY 14850
| | - Riasat Zaman
- Weill Institute for Cell and Molecular Biology, Department of Molecular Biology and Genetics, Cornell University, Ithaca NY 14850
| | - Anthony Bretscher
- Weill Institute for Cell and Molecular Biology, Department of Molecular Biology and Genetics, Cornell University, Ithaca NY 14850
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Zhang L, Ding L, Li Y, Zhang F, Xu Y, Pan H, Wan X, Yan G, Yu F, Li R. EHD3 positively regulated by NR5A1 participates in testosterone synthesis via endocytosis. Life Sci 2021; 278:119570. [PMID: 33964295 DOI: 10.1016/j.lfs.2021.119570] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 04/19/2021] [Accepted: 04/25/2021] [Indexed: 01/23/2023]
Abstract
AIMS Increasing evidence has shown that hormone secretion is regulated by endocytosis. Eps15 homology domain-containing protein 3 (EHD3) is an endocytic-trafficking regulatory protein, but whether EHD3 is associated with testosterone secretion is not clear. This work aims to explore the role of EHD3 in testosterone synthesis. MAIN METHODS Testosterone concentration was determined by ELISA. The effects of EHD3 on endocytosis were assessed by exosomes tracing assay and Immunofluorescence. Targeting relationship between EHD3 and NR5A1 was verified by chromatin immunoprecipitation (ChIP) and dual luciferase reporter gene assay in Leydig cells. For in vivo assessments, conditional NR5A1 knockout mouse model was established with CRISPR/Cas9 gene targeting technology. KEY FINDINGS EHD3 overexpression significantly increased the concentration of testosterone. EHD3 knockdown markedly decreased testosterone synthesis by reducing endocytosis. The activity of the EHD3 promoter was positively regulated by NR5A1, which occupied the conserved sequence "AGGTCA" in the EHD3 promoter. Furthermore, mice with a Leydig cell-specific conditional NR5A1 knockout displayed the blunted levels of EHD3 and clathrin (a key factor for endocytosis), and serum testosterone concentration compared with NR5A1f/f mice. SIGNIFICANCE This study suggests a potential molecular mechanism of testosterone synthesis to fully understand male reproductive health.
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Affiliation(s)
- Lingling Zhang
- NHC Key Lab of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), School of Pharmacy, Fudan University, Shanghai 200032, China; NHC Key Lab of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Fudan University, Shanghai 200032, China; Center for Reproductive Medicine, Drum Tower Clinic Medical College of Nanjing Medical University, Nanjing 210008, China; Center for Molecular Reproductive Medicine, Nanjing University, Nanjing 210008, China
| | - Lijun Ding
- Center for Reproductive Medicine, Drum Tower Clinic Medical College of Nanjing Medical University, Nanjing 210008, China; Center for Molecular Reproductive Medicine, Nanjing University, Nanjing 210008, China; Clinical Center for Stem Cell Research, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008, China
| | - Yifan Li
- Center for Reproductive Medicine, Drum Tower Clinic Medical College of Nanjing Medical University, Nanjing 210008, China; Center for Molecular Reproductive Medicine, Nanjing University, Nanjing 210008, China
| | - Fangxi Zhang
- NHC Key Lab of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), School of Pharmacy, Fudan University, Shanghai 200032, China; NHC Key Lab of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Fudan University, Shanghai 200032, China
| | - Yanhong Xu
- Center for Reproductive Medicine, Drum Tower Clinic Medical College of Nanjing Medical University, Nanjing 210008, China; Center for Molecular Reproductive Medicine, Nanjing University, Nanjing 210008, China
| | - Hongjie Pan
- NHC Key Lab of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Fudan University, Shanghai 200032, China
| | - Xiaofeng Wan
- NHC Key Lab of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Fudan University, Shanghai 200032, China
| | - Guijun Yan
- Center for Reproductive Medicine, Drum Tower Clinic Medical College of Nanjing Medical University, Nanjing 210008, China; Center for Molecular Reproductive Medicine, Nanjing University, Nanjing 210008, China
| | - Fei Yu
- Center for Experimental Animal, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008, China.
| | - Runsheng Li
- NHC Key Lab of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), School of Pharmacy, Fudan University, Shanghai 200032, China; NHC Key Lab of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Fudan University, Shanghai 200032, China.
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