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Byun H, Singh GB, Xu WK, Das P, Reyes A, Battenhouse A, Wylie DC, Santiago ML, Lozano MM, Dudley JP. Apobec-mediated retroviral hypermutation in vivo is dependent on mouse strain. PLoS Pathog 2024; 20:e1012505. [PMID: 39208378 DOI: 10.1371/journal.ppat.1012505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 09/11/2024] [Accepted: 08/14/2024] [Indexed: 09/04/2024] Open
Abstract
Replication of the complex retrovirus mouse mammary tumor virus (MMTV) is antagonized by murine Apobec3 (mA3), a member of the Apobec family of cytidine deaminases. We have shown that MMTV-encoded Rem protein inhibits proviral mutagenesis by the Apobec enzyme, activation-induced cytidine deaminase (AID) during viral replication in BALB/c mice. To further study the role of Rem in vivo, we have infected C57BL/6 (B6) mice with a superantigen-independent lymphomagenic strain of MMTV (TBLV-WT) or a mutant strain that is defective in Rem and its cleavage product Rem-CT (TBLV-SD). Compared to BALB/c, B6 mice were more susceptible to TBLV infection and tumorigenesis. Furthermore, unlike MMTV, TBLV induced T-cell tumors in B6 μMT mice, which lack membrane-bound IgM and conventional B-2 cells. At limiting viral doses, loss of Rem expression in TBLV-SD-infected B6 mice accelerated tumorigenesis compared to TBLV-WT in either wild-type B6 or AID-knockout mice. Unlike BALB/c results, high-throughput sequencing indicated that proviral G-to-A or C-to-T mutations were unchanged regardless of Rem expression in B6 tumors. However, knockout of both AID and mA3 reduced G-to-A mutations. Ex vivo stimulation showed higher levels of mA3 relative to AID in B6 compared to BALB/c splenocytes, and effects of agonists differed in the two strains. RNA-Seq revealed increased transcripts related to growth factor and cytokine signaling in TBLV-SD-induced tumors relative to TBLV-WT-induced tumors, consistent with another Rem function. Thus, Rem-mediated effects on tumorigenesis in B6 mice are independent of Apobec-mediated proviral hypermutation.
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Affiliation(s)
- Hyewon Byun
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Gurvani B Singh
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Wendy Kaichun Xu
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Poulami Das
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Alejandro Reyes
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Anna Battenhouse
- Center for Biomedical Research Support, The University of Texas at Austin, Austin, Texas, United States of America
| | - Dennis C Wylie
- Center for Biomedical Research Support, The University of Texas at Austin, Austin, Texas, United States of America
| | - Mario L Santiago
- Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Mary M Lozano
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Jaquelin P Dudley
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
- LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, Texas, United States of America
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Guan L, Ge R, Ma S. Newsights of endoplasmic reticulum in hypoxia. Biomed Pharmacother 2024; 175:116812. [PMID: 38781866 DOI: 10.1016/j.biopha.2024.116812] [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: 04/15/2024] [Revised: 05/19/2024] [Accepted: 05/20/2024] [Indexed: 05/25/2024] Open
Abstract
The endoplasmic reticulum (ER) is important to cells because of its essential functions, including synthesizing three major nutrients and ion transport. When cellular homeostasis is disrupted, ER quality control (ERQC) system is activated effectively to remove misfolded and unfolded proteins through ER-phagy, ER-related degradation (ERAD), and molecular chaperones. When unfolded protein response (UPR) and ER stress are activated, the cell may be suffering a huge blow, and the most probable consequence is apoptosis. The membrane contact points between the ER and sub-organelles contribute to communication between the organelles. The decrease in oxygen concentration affects the morphology and structure of the ER, thereby affecting its function and further disrupting the stable state of cells, leading to the occurrence of disease. In this study, we describe the functions of ER-, ERQC-, and ER-related membrane contact points and their changes under hypoxia, which will help us further understand ER and treat ER-related diseases.
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Affiliation(s)
- Lu Guan
- Qinghai University, Xining, Qinghai, China
| | - Rili Ge
- Key Laboratory of the Ministry of High Altitude Medicine, Qinghai University, Xining, Qinghai, China; Key Laboratory of Applied Fundamentals of High Altitude Medicine, (Qinghai-Utah Joint Key Laboratory of Plateau Medicine), Qinghai University, Xining, Qinghai, China; Laboratory for High Altitude Medicine of Qinghai Province, Qinghai University, Xining, Qinghai, China
| | - Shuang Ma
- Key Laboratory of the Ministry of High Altitude Medicine, Qinghai University, Xining, Qinghai, China; Key Laboratory of Applied Fundamentals of High Altitude Medicine, (Qinghai-Utah Joint Key Laboratory of Plateau Medicine), Qinghai University, Xining, Qinghai, China; Laboratory for High Altitude Medicine of Qinghai Province, Qinghai University, Xining, Qinghai, China.
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Hochman J, Braitbard O. Life after Cleavage: The Story of a β-Retroviral (MMTV) Signal Peptide-From Murine Lymphoma to Human Breast Cancer. Viruses 2022; 14:v14112435. [PMID: 36366533 PMCID: PMC9694287 DOI: 10.3390/v14112435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 10/31/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022] Open
Abstract
An increasing body of evidence in recent years supports an association of the betaretrovirus mouse mammary tumor virus (MMTV) with human breast cancer. This is an issue that still raises heated controversy. We have come to address this association using the signal peptide p14 of the MMTV envelope precursor protein as a key element of our strategy. In addition to its signal peptide function, p14 has some significant post endoplasmic reticulum (ER)-targeting characteristics: (1) it localizes to nucleoli where it binds key proteins (RPL5 and B23) involved (among other activities) in the regulation of nucleolar stress response, ribosome biogenesis and p53 stabilization; (2) p14 is a nuclear export factor; (3) it is expressed on the cell surface of infected cells, and as such, is amenable to, and successfully used, in preventive vaccination against experimental tumors that harbor MMTV; (4) the growth of such tumors is impaired in vivo using a combination of monoclonal anti-p14 antibodies or adoptive T-cell transfer treatments; (5) p14 is a phospho-protein endogenously phosphorylated by two different serine kinases. The phosphorylation status of the two sites determines whether p14 will function in an oncogenic or tumor-suppressing capacity; (6) transcriptional activation of genes (RPL5, ErbB4) correlates with the oncogenic potential of MMTV; (7) finally, polyclonal anti-p14 antibodies have been applied in immune histochemistry analyses of breast cancer cases using formalin fixed paraffin-embedded sections, supporting the associations of MMTV with the disease. Taken together, the above findings constitute a road map towards the diagnosis and possible prevention and treatment of MMTV-associated breast cancer.
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Affiliation(s)
- Jacob Hochman
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
- Correspondence: ; Tel.: +972-54-441-4370
| | - Ori Braitbard
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
- Department of Bioinformatics, The Faculty of Life and Health Sciences, Jerusalem College of Technology, Jerusalem 9372115, Israel
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