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Allen KN, Torres-Velarde JM, Vazquez JM, Moreno-Santillán DD, Sudmant PH, Vázquez-Medina JP. Hypoxia exposure blunts angiogenic signaling and upregulates the antioxidant system in endothelial cells derived from elephant seals. BMC Biol 2024; 22:91. [PMID: 38654271 PMCID: PMC11040891 DOI: 10.1186/s12915-024-01892-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 04/17/2024] [Indexed: 04/25/2024] Open
Abstract
BACKGROUND Elephant seals exhibit extreme hypoxemic tolerance derived from repetitive hypoxia/reoxygenation episodes they experience during diving bouts. Real-time assessment of the molecular changes underlying protection against hypoxic injury in seals remains restricted by their at-sea inaccessibility. Hence, we developed a proliferative arterial endothelial cell culture model from elephant seals and used RNA-seq, functional assays, and confocal microscopy to assess the molecular response to prolonged hypoxia. RESULTS Seal and human endothelial cells exposed to 1% O2 for up to 6 h respond differently to acute and prolonged hypoxia. Seal cells decouple stabilization of the hypoxia-sensitive transcriptional regulator HIF-1α from angiogenic signaling. Rapid upregulation of genes involved in glutathione (GSH) metabolism supports the maintenance of GSH pools, and intracellular succinate increases in seal but not human cells. High maximal and spare respiratory capacity in seal cells after hypoxia exposure occurs in concert with increasing mitochondrial branch length and independent from major changes in extracellular acidification rate, suggesting that seal cells recover oxidative metabolism without significant glycolytic dependency after hypoxia exposure. CONCLUSIONS We found that the glutathione antioxidant system is upregulated in seal endothelial cells during hypoxia, while this system remains static in comparable human cells. Furthermore, we found that in contrast to human cells, hypoxia exposure rapidly activates HIF-1 in seal cells, but this response is decoupled from the canonical angiogenesis pathway. These results highlight the unique mechanisms that confer extraordinary tolerance to limited oxygen availability in a champion diving mammal.
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Affiliation(s)
- Kaitlin N Allen
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA, 94720, USA
| | | | - Juan Manuel Vazquez
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA, 94720, USA
| | | | - Peter H Sudmant
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA, 94720, USA
- Center for Computational Biology, University of California Berkeley, Berkeley, CA, 94720, USA
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Allen KN, Torres-Velarde JM, Vazquez JM, Moreno-Santillan DD, Sudmant PH, Vázquez-Medina JP. Hypoxia blunts angiogenic signaling and upregulates the antioxidant system in elephant seal endothelial cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.01.547248. [PMID: 37461722 PMCID: PMC10350019 DOI: 10.1101/2023.07.01.547248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2024]
Abstract
Elephant seals experience extreme hypoxemia during diving bouts. Similar depletions in oxygen availability characterize pathologies including myocardial infarction and ischemic stroke in humans, but seals manage these repeated episodes without injury. However, the real-time assessment of the molecular changes underlying protection against hypoxic injury in seals remains restricted by their at-sea inaccessibility. Hence, we developed a proliferative arterial endothelial cell culture system to assess the molecular response to prolonged hypoxia. Seal and human cells exposed to 1% O 2 for up to 6 h demonstrated differential responses to both acute and prolonged hypoxia. Seal cells decouple stabilization of the hypoxia-sensitive transcriptional regulator HIF-1α from angiogenic signaling at both the transcriptional and cellular level. Rapid upregulation of genes involved in the glutathione (GSH) metabolism pathway supported maintenance of GSH pools and increases in intracellular succinate in seal but not human cells during hypoxia exposure. High maximal and spare respiratory capacity in seal cells after hypoxia exposure occurred in concert with increasing mitochondrial branch length and independent from major changes in extracellular acidification rate, suggesting seal cells recover oxidative metabolism without significant glycolytic dependency after hypoxia exposure. In sum, our studies show that in contrast to human cells, seal cells adapt to hypoxia exposure by dampening angiogenic signaling, increasing antioxidant protection, and maintaining mitochondrial morphological integrity and function.
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Zeng G, Wang T, Zhang J, Kang YJ, Feng L. FLI1 mediates the selective expression of hypoxia-inducible factor 1 target genes in endothelial cells under hypoxic conditions. FEBS Open Bio 2021. [PMID: 34102031 PMCID: PMC8329784 DOI: 10.1002/2211-5463.13220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 05/13/2021] [Accepted: 06/07/2021] [Indexed: 02/05/2023] Open
Abstract
The selective expression of hypoxia‐inducible factor (HIF) target genes in different physiological and pathological environments forms the basis for cellular adaptation to hypoxia in development and disease. Several E26 transformation‐specific (ETS) transcription factors have been shown to specifically regulate the expression of a subset of HIF‐2 target genes. However, it is unknown whether there are ETS factors that specifically regulate hypoxia‐induced HIF‐1 target genes. The present study was undertaken to explore whether friend leukemia integration 1 (FLI1), an ETS transcription factor, regulates the expression of HIF‐1 target genes. To investigate this possibility, EA.hy926 cells were exposed to 20% O2 (normoxia) or 1% O2 (hypoxia). Western blotting, immunofluorescence staining, and RT‐qPCR revealed that FLI1 mRNA and protein levels increased slightly and that the FLI1 protein co‐localized with HIF‐1α in the nucleus under hypoxic conditions. Further analysis showed that, in the absence of FLI1, the hypoxia‐mediated induction of HIF‐1 target genes was selectively inhibited. The results from immunoprecipitation and luciferase reporter assays indicated that FLI1 cooperates with HIF‐1α and is required for the transcriptional activation of a subset of HIF‐1 target genes with a core promoter region containing FBS in proximity to a functional hypoxia response element (HRE). Furthermore, ChIP analysis further confirmed the direct interaction between FLI1 and the promoter region of FLI1‐dependent HIF‐1 target genes under hypoxia. Together, this study demonstrates that FLI1 is involved in the transactivation of certain HIF‐1 target genes in endothelial cells under hypoxic conditions.
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Affiliation(s)
- Guodan Zeng
- Key Laboratory of Transplant Engineering and Immunology, Ministry of Health, West China Hospital, Sichuan University, Chengdu, China.,Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Tao Wang
- Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Jingyao Zhang
- Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Y James Kang
- Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China.,Memphis Institute of Regenerative Medicine, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Li Feng
- Key Laboratory of Transplant Engineering and Immunology, Ministry of Health, West China Hospital, Sichuan University, Chengdu, China.,Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
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Kang Y, Wu T, He Y, He Y, Zhao D. Elf4 regulates lysosomal biogenesis and the mTOR pathway to promote clearance of Staphylococcus aureus in macrophages. FEBS Lett 2021; 595:881-891. [PMID: 33423322 DOI: 10.1002/1873-3468.14037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/16/2020] [Accepted: 12/17/2020] [Indexed: 11/10/2022]
Abstract
Staphylococcus aureus is a major cause of infectious disease. Macrophages can directly destroy most of the invading bacteria through the phagolysosomal pathway. E74-like factor 4 (Elf4) is one of the important transcription factors that controls diverse pathogens, but the role of Elf4 in macrophage-mediated S. aureus eradication is unknown. Our data show that Elf4 is induced by S. aureus in macrophages. Elevated expression of Elf4 results in decreased bacterial load and inflammatory responses during S. aureus infection in vivo and in vitro. Elf4-overexpressed macrophages have decreased mTOR activity and increased lysosomal mass. Collectively, these results suggest that S. aureus induces Elf4 expression, which enhances lysosomal function and increases the capacity of macrophages to eliminate intracellular pathogens.
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Affiliation(s)
- Yanhua Kang
- Hangzhou Key Lab of Inflammation and Immunoregulation, Department of Basic Medical Science, School of Medicine, Hangzhou Normal University, China
| | - Tingyue Wu
- Hangzhou Key Lab of Inflammation and Immunoregulation, Department of Basic Medical Science, School of Medicine, Hangzhou Normal University, China
| | - Yan He
- Hangzhou Key Lab of Inflammation and Immunoregulation, Department of Basic Medical Science, School of Medicine, Hangzhou Normal University, China
| | - Yunfan He
- Hangzhou Key Lab of Inflammation and Immunoregulation, Department of Basic Medical Science, School of Medicine, Hangzhou Normal University, China
| | - Dongjiu Zhao
- Hangzhou Key Lab of Inflammation and Immunoregulation, Department of Basic Medical Science, School of Medicine, Hangzhou Normal University, China
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Suico MA, Shuto T, Kai H. Roles and regulations of the ETS transcription factor ELF4/MEF. J Mol Cell Biol 2018; 9:168-177. [PMID: 27932483 PMCID: PMC5907832 DOI: 10.1093/jmcb/mjw051] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 12/21/2016] [Indexed: 12/12/2022] Open
Abstract
Most E26 transformation-specific (ETS) transcription factors are involved in the pathogenesis and progression of cancer. This is in part due to the roles of ETS transcription factors in basic biological processes such as growth, proliferation, and differentiation, and also because of their regulatory functions that have physiological relevance in tumorigenesis, immunity, and basal cellular homoeostasis. A member of the E74-like factor (ELF) subfamily of the ETS transcription factor family—myeloid elf-1-like factor (MEF), designated as ELF4—has been shown to be critically involved in immune response and signalling, osteogenesis, adipogenesis, cancer, and stem cell quiescence. ELF4 carries out these functions as a transcriptional activator or through interactions with its partner proteins. Mutations in ELF4 cause aberrant interactions and induce downstream processes that may lead to diseased cells. Knowing how ELF4 impinges on certain cellular processes and how it is regulated in the cells can lead to a better understanding of the physiological and pathological consequences of modulated ELF4 activity.
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Affiliation(s)
- Mary Ann Suico
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Kumamoto 862-0973, Japan
| | - Tsuyoshi Shuto
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Kumamoto 862-0973, Japan
| | - Hirofumi Kai
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Kumamoto 862-0973, Japan
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Kudo E, Taura M, Suico MA, Goto H, Kai H, Okada S. Transcriptional regulation of HIV-1 host factor COMMD1 by the Sp family. Int J Mol Med 2018; 41:2366-2374. [PMID: 29336469 DOI: 10.3892/ijmm.2018.3386] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 01/09/2018] [Indexed: 11/05/2022] Open
Abstract
Copper metabolism Murr1 domain containing 1 (COMMD1) has multiple functions in the regulation of protein stability at the plasma membrane and in the cytoplasm. However, the regulation of COMMD1 transcriptional has remained to be elucidated. In the present study, the 5'‑flanking region (‑1,192/+83 bp) of the human COMMD1 gene was cloned. It was observed that the COMMD1 promoter region contains GC‑rich region that has 7 putative Sp1‑binding sites via in silico analysis. The proximal promoter region at ‑289/+83 bp was required for COMMD1 basal promoter activity by deletion constructs of COMMD1 promoter. Moreover, Sp1 inhibitor, mithramycin A, suppressed basal COMMD1 promoter activity. The Sp1‑binding site (‑11/‑1 bp) in the proximal promoter region was a critical site for COMMD1 gene regulation by Sp1 and Sp3. Sp1 upregulated COMMD1 promoter activity, whereas Sp3 suppressed it. Endogenous Sp1 and Sp3 bound to the proximal promoter region of COMMD1. Taken together, Sp1 constitutively regulates the basal expression of the COMMD1 gene in human epithelial cell lines.
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Affiliation(s)
- Eriko Kudo
- Division of Hematopoiesis, Center for AIDS Research, Kumamoto University, Kumamoto 860‑0811, Japan
| | - Manabu Taura
- Division of Hematopoiesis, Center for AIDS Research, Kumamoto University, Kumamoto 860‑0811, Japan
| | - Mary Ann Suico
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862‑0973, Japan
| | - Hiroki Goto
- Division of Hematopoiesis, Center for AIDS Research, Kumamoto University, Kumamoto 860‑0811, Japan
| | - Hirofumi Kai
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862‑0973, Japan
| | - Seiji Okada
- Division of Hematopoiesis, Center for AIDS Research, Kumamoto University, Kumamoto 860‑0811, Japan
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