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Ruhoff VT, Leijnse N, Doostmohammadi A, Bendix PM. Filopodia: integrating cellular functions with theoretical models. Trends Cell Biol 2024:S0962-8924(24)00113-2. [PMID: 38969554 DOI: 10.1016/j.tcb.2024.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 05/24/2024] [Accepted: 05/27/2024] [Indexed: 07/07/2024]
Abstract
Filopodia, widely distributed on cell surfaces, are distinguished by their dynamic extensions, playing pivotal roles in a myriad of biological processes. Their functions span from mechanosensing and guidance to cell-cell communication during cellular organization in the early embryo. Filopodia have significant roles in pathogenic processes, such as cancer invasion and viral dissemination. Molecular mapping of the filopodome has revealed generic components essential for filopodia functions. In parallel, recent insights into biophysical mechanisms governing filopodia dynamics have provided the foundation for broader investigations of filopodia's biological functions. We highlight recent discoveries of engagement of filopodia in various stages of development and pathogenesis and present an overview of intricate molecular and physical features of these cellular structures across a spectrum of cellular activities.
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Affiliation(s)
| | - Natascha Leijnse
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 København Ø, Denmark
| | - Amin Doostmohammadi
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 København Ø, Denmark
| | - Poul Martin Bendix
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 København Ø, Denmark.
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2
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Misra J, Carlson KR, Spandau DF, Wek RC. Multiple mechanisms activate GCN2 eIF2 kinase in response to diverse stress conditions. Nucleic Acids Res 2024; 52:1830-1846. [PMID: 38281137 PMCID: PMC10899773 DOI: 10.1093/nar/gkae006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 12/22/2023] [Accepted: 01/02/2024] [Indexed: 01/30/2024] Open
Abstract
Diverse environmental insults induce the integrated stress response (ISR), which features eIF2 phosphorylation and translational control that serves to restore protein homeostasis. The eIF2 kinase GCN2 is a first responder in the ISR that is activated by amino acid depletion and other stresses not directly related to nutrients. Two mechanisms are suggested to trigger an ordered process of GCN2 activation during stress: GCN2 monitoring stress via accumulating uncharged tRNAs or by stalled and colliding ribosomes. Our results suggest that while ribosomal collisions are indeed essential for GCN2 activation in response to translational elongation inhibitors, conditions that trigger deacylation of tRNAs activate GCN2 via its direct association with affected tRNAs. Both mechanisms require the GCN2 regulatory domain related to histidyl tRNA synthetases. GCN2 activation by UV irradiation features lowered amino acids and increased uncharged tRNAs and UV-induced ribosome collisions are suggested to be dispensable. We conclude that there are multiple mechanisms that activate GCN2 during diverse stresses.
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Affiliation(s)
- Jagannath Misra
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS4067 Indianapolis, Indiana 46202, USA
| | - Kenneth R Carlson
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS4067 Indianapolis, Indiana 46202, USA
| | - Dan F Spandau
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS4067 Indianapolis, Indiana 46202, USA
- Department of Dermatology, Indiana University School of Medicine, 635 Barnhill Drive, MS4067 Indianapolis, Indiana 46202, USA
- Richard L. Roudebush Veterans Administration Medical Center, Indiana University School of Medicine, 635 Barnhill Drive, MS4067 Indianapolis, Indiana 46202, USA
| | - Ronald C Wek
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS4067 Indianapolis, Indiana 46202, USA
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3
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Hou Y, Wei D, Zhang Z, Lei T, Li S, Bao J, Guo H, Tan L, Xie X, Zhuang Y, Lu Z, Zhao Y. Downregulation of nutrition sensor GCN2 in macrophages contributes to poor wound healing in diabetes. Cell Rep 2024; 43:113658. [PMID: 38175755 DOI: 10.1016/j.celrep.2023.113658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 11/27/2023] [Accepted: 12/20/2023] [Indexed: 01/06/2024] Open
Abstract
Poor skin wound healing, which is common in patients with diabetes, is related to imbalanced macrophage polarization. Here, we find that nutrition sensor GCN2 (general control nonderepressible 2) and its downstream are significantly upregulated in human skin wound tissue and mouse skin wound macrophages, but skin wound-related GCN2 expression and activity are significantly downregulated by diabetes and hyperglycemia. Using wound healing models of GCN2-deleted mice, bone marrow chimeric mice, and monocyte-transferred mice, we show that GCN2 deletion in macrophages significantly delays skin wound healing compared with wild-type mice by altering M1 and M2a/M2c polarization. Mechanistically, GCN2 inhibits M1 macrophages via OXPHOS-ROS-NF-κB pathway and promotes tissue-repairing M2a/M2c macrophages through eukaryotic translation initiation factor 2 (eIF2α)-hypoxia-inducible factor 1α (HIF1α)-glycolysis pathway. Importantly, local supplementation of GCN2 activator halofuginone efficiently restores wound healing in diabetic mice with re-balancing M1 and M2a/2c polarization. Thus, the decreased macrophage GCN2 expression and activity contribute to poor wound healing in diabetes and targeting GCN2 improves wound healing in diabetes.
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Affiliation(s)
- Yangxiao Hou
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Dong Wei
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China; CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Faculty of Synthetic Biology, Shenzhen Institute of Advanced Technology, Shenzhen, China
| | - Zhaoqi Zhang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China; CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Faculty of Synthetic Biology, Shenzhen Institute of Advanced Technology, Shenzhen, China
| | - Tong Lei
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China; Beijing Institute for Stem Cell and Regeneration, Beijing, China
| | - Sihong Li
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Jiaming Bao
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Han Guo
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Liang Tan
- Kidney Transplantation Department, Second Xiangya Hospital of Central South University, Changsha, China
| | - Xubiao Xie
- Kidney Transplantation Department, Second Xiangya Hospital of Central South University, Changsha, China
| | - Yuan Zhuang
- Department of Blood Transfusion, First Medical Center of Chinese PLA General Hospital, Beijing, China
| | - Zhongbing Lu
- University of Chinese Academy of Sciences, Beijing, China.
| | - Yong Zhao
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China; CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Faculty of Synthetic Biology, Shenzhen Institute of Advanced Technology, Shenzhen, China; Beijing Institute for Stem Cell and Regeneration, Beijing, China.
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Levy JL, Mirek ET, Rodriguez EM, Zalma B, Burns J, Jonsson WO, Sampath H, Staschke KA, Wek RC, Anthony TG. GCN2 is required to maintain core body temperature in mice during acute cold. Am J Physiol Endocrinol Metab 2023; 325:E624-E637. [PMID: 37792040 PMCID: PMC10864021 DOI: 10.1152/ajpendo.00181.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 09/01/2023] [Accepted: 09/29/2023] [Indexed: 10/05/2023]
Abstract
Nonshivering thermogenesis in rodents requires macronutrients to fuel the generation of heat during hypothermic conditions. In this study, we examined the role of the nutrient sensing kinase, general control nonderepressible 2 (GCN2) in directing adaptive thermogenesis during acute cold exposure in mice. We hypothesized that GCN2 is required for adaptation to acute cold stress via activation of the integrated stress response (ISR) resulting in liver production of FGF21 and increased amino acid transport to support nonshivering thermogenesis. In alignment with our hypothesis, female and male mice lacking GCN2 failed to adequately increase energy expenditure and veered into torpor. Mice administered a small molecule inhibitor of GCN2 were also profoundly intolerant to acute cold stress. Gcn2 deletion also impeded liver-derived FGF21 but in males only. Within the brown adipose tissue (BAT), acute cold exposure increased ISR activation and its transcriptional execution in males and females. RNA sequencing in BAT identified transcripts that encode actomyosin mechanics and transmembrane transport as requiring GCN2 during cold exposure. These transcripts included class II myosin heavy chain and amino acid transporters, critical for maximal thermogenesis during cold stress. Importantly, Gcn2 deletion corresponded with higher circulating amino acids and lower intracellular amino acids in the BAT during cold stress. In conclusion, we identify a sex-independent role for GCN2 activation to support adaptive thermogenesis via uptake of amino acids into brown adipose.NEW & NOTEWORTHY This paper details the discovery that GCN2 activation is required in both male and female mice to maintain core body temperature during acute cold exposure. The results point to a novel role for GCN2 in supporting adaptive thermogenesis via amino acid transport and actomyosin mechanics in brown adipose tissue.
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Affiliation(s)
- Jordan L Levy
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - Emily T Mirek
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - Esther M Rodriguez
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - Brian Zalma
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - Jeffrey Burns
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - William O Jonsson
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - Harini Sampath
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - Kirk A Staschke
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States
- Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, United States
| | - Ronald C Wek
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States
- Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, United States
| | - Tracy G Anthony
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
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Lin S, Ye MY, Fu QY, Pan CL, Liu YJ, Zheng LM, Hong Q, Chen YH. Cholic acid exposure during late pregnancy causes placental dysfunction and fetal growth restriction by reactive oxygen species-mediated activation of placental GCN2/eIF2α pathway. FASEB J 2023; 37:e22820. [PMID: 36801982 DOI: 10.1096/fj.202202126r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/19/2023] [Accepted: 01/30/2023] [Indexed: 02/23/2023]
Abstract
Epidemiological studies suggest that fetal growth restriction (FGR) caused by gestational cholestasis is associated with elevated serum cholic acid (CA). Here, we explore the mechanism by which CA induces FGR. Pregnant mice except controls were orally administered with CA daily from gestational day 13 (GD13) to GD17. Results found that CA exposure decreased fetal weight and crown-rump length, and increased the incidence of FGR in a dose-dependent manner. Furthermore, CA caused placental glucocorticoid (GC) barrier dysfunction via down-regulating the protein but not the mRNA level of placental 11β-Hydroxysteroid dehydrogenase-2 (11β-HSD2). Additionally, CA activated placental GCN2/eIF2α pathway. GCN2iB, an inhibitor of GCN2, significantly inhibited CA-induced down-regulation of 11β-HSD2 protein. We further found that CA caused excessive reactive oxygen species (ROS) production and oxidative stress in mouse placentas and human trophoblasts. NAC significantly rescued CA-induced placental barrier dysfunction by inhibiting activation of GCN2/eIF2α pathway and subsequent down-regulation of 11β-HSD2 protein in placental trophoblasts. Importantly, NAC rescued CA-induced FGR in mice. Overall, our results suggest that CA exposure during late pregnancy induces placental GC barrier dysfunction and subsequent FGR may be via ROS-mediated placental GCN2/eIF2α activation. This study provides valuable insight for understanding the mechanism of cholestasis-induced placental dysfunction and subsequent FGR.
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Affiliation(s)
- Shuai Lin
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Meng-Ying Ye
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Qian-Yun Fu
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Chao-Lin Pan
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Ya-Jie Liu
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Li-Ming Zheng
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Qiang Hong
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Yuan-Hua Chen
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China.,Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei, China
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Zhao C, Guo H, Hou Y, Lei T, Wei D, Zhao Y. Multiple Roles of the Stress Sensor GCN2 in Immune Cells. Int J Mol Sci 2023; 24:ijms24054285. [PMID: 36901714 PMCID: PMC10002013 DOI: 10.3390/ijms24054285] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 02/16/2023] [Accepted: 02/17/2023] [Indexed: 02/24/2023] Open
Abstract
The serine/threonine-protein kinase general control nonderepressible 2 (GCN2) is a well-known stress sensor that responds to amino acid starvation and other stresses, making it critical to the maintenance of cellular and organismal homeostasis. More than 20 years of research has revealed the molecular structure/complex, inducers/regulators, intracellular signaling pathways and bio-functions of GCN2 in various biological processes, across an organism's lifespan, and in many diseases. Accumulated studies have demonstrated that the GCN2 kinase is also closely involved in the immune system and in various immune-related diseases, such as GCN2 acts as an important regulatory molecule to control macrophage functional polarization and CD4+ T cell subset differentiation. Herein, we comprehensively summarize the biological functions of GCN2 and discuss its roles in the immune system, including innate and adaptive immune cells. We also discuss the antagonism of GCN2 and mTOR pathways in immune cells. A better understanding of GCN2's functions and signaling pathways in the immune system under physiological, stressful, and pathological situations will be beneficial to the development of potential therapies for many immune-relevant diseases.
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Affiliation(s)
- Chenxu Zhao
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Han Guo
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yangxiao Hou
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tong Lei
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dong Wei
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yong Zhao
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing 100101, China
- Correspondence: ; Tel.: +86-10-64807302
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7
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The role of eIF2 phosphorylation in cell and organismal physiology: new roles for well-known actors. Biochem J 2022; 479:1059-1082. [PMID: 35604373 DOI: 10.1042/bcj20220068] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 04/21/2022] [Accepted: 04/25/2022] [Indexed: 02/06/2023]
Abstract
Control of protein synthesis (mRNA translation) plays key roles in shaping the proteome and in many physiological, including homeostatic, responses. One long-known translational control mechanism involves phosphorylation of initiation factor, eIF2, which is catalysed by any one of four protein kinases, which are generally activated in response to stresses. They form a key arm of the integrated stress response (ISR). Phosphorylated eIF2 inhibits eIF2B (the protein that promotes exchange of eIF2-bound GDP for GTP) and thus impairs general protein synthesis. However, this mechanism actually promotes translation of certain mRNAs by virtue of specific features they possess. Recent work has uncovered many previously unknown features of this regulatory system. Several studies have yielded crucial insights into the structure and control of eIF2, including that eIF2B is regulated by several metabolites. Recent studies also reveal that control of eIF2 and the ISR helps determine organismal lifespan and surprising roles in sensing mitochondrial stresses and in controlling the mammalian target of rapamycin (mTOR). The latter effect involves an unexpected role for one of the eIF2 kinases, HRI. Phosphoproteomic analysis identified new substrates for another eIF2 kinase, Gcn2, which senses the availability of amino acids. Several genetic disorders arise from mutations in genes for eIF2α kinases or eIF2B (i.e. vanishing white matter disease, VWM and microcephaly, epileptic seizures, microcephaly, hypogenitalism, diabetes and obesity, MEHMO). Furthermore, the eIF2-mediated ISR plays roles in cognitive decline associated with Alzheimer's disease. New findings suggest potential therapeutic value in interfering with the ISR in certain settings, including VWM, for example by using compounds that promote eIF2B activity.
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