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Wang J, Xu L, Yun X, Yang K, Liao D, Tian L, Jiang H, Lu W. Proteomic analysis reveals that proteasome subunit beta 6 is involved in hypoxia-induced pulmonary vascular remodeling in rats. PLoS One 2013; 8:e67942. [PMID: 23844134 PMCID: PMC3700908 DOI: 10.1371/journal.pone.0067942] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 05/23/2013] [Indexed: 11/25/2022] Open
Abstract
Background Chronic hypoxia (CH) is known to be one of the major causes of pulmonary hypertension (PH), which is characterized by sustained elevation of pulmonary vascular resistance resulting from vascular remodeling. In this study, we investigated whether the ubiquitin proteasome system (UPS) was involved in the mechanism of hypoxia-induced pulmonary vascular remodeling. We isolated the distal pulmonary artery (PA) from a previously defined chronic hypoxic pulmonary hypertension (CHPH) rat model, performed proteomic analyses in search of differentially expressed proteins belonging to the UPS, and subsequently identified their roles in arterial remodeling. Results Twenty-two proteins were differently expressed between the CH and normoxic group. Among them, the expression of proteasome subunit beta (PSMB) 1 and PSMB6 increased after CH exposure. Given that PSMB1 is a well-known structural subunit and PSMB6 is a functional subunit, we sought to assess whether PSMB6 could be related to the multiple functional changes during the CHPH process. We confirmed the proteomic results by real-time PCR and Western blot. With the increase in quantity of the active subunit, proteasome activity in both cultured pulmonary artery smooth muscle cells (PASMCs) and isolated PA from the hypoxic group increased. An MTT assay revealed that the proteasome inhibitor MG132 was able to attenuate the hypoxia-induced proliferation of PASMC in a dose-dependent manner. Knockdown of PSMB6 using siRNA also prevented hypoxia-induced proliferation. Conclusion The present study revealed the association between increased PSMB6 and CHPH. CH up-regulated proteasome activity and the proliferation of PASMCs, which may have been related to increased PSMB6 expression and the subsequently enhanced functional catalytic sites of the proteasome. These results suggested an essential role of the proteasome during CHPH development, a novel finding requiring further study.
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Affiliation(s)
- Jian Wang
- Guangzhou Institute of Respiratory Diseases, State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, Guangdong, China
- Division of Pulmonary and Critical Care Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail: (WL); (JW)
| | - Lei Xu
- Guangzhou Institute of Respiratory Diseases, State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, Guangdong, China
- Division of Pulmonary and Critical Care Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Xin Yun
- Guangzhou Institute of Respiratory Diseases, State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, Guangdong, China
- Division of Pulmonary and Critical Care Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Kai Yang
- Guangzhou Institute of Respiratory Diseases, State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, Guangdong, China
- Division of Pulmonary and Critical Care Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Dongjiang Liao
- Guangzhou Institute of Respiratory Diseases, State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Lichun Tian
- Guangzhou Institute of Respiratory Diseases, State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Haiyang Jiang
- Division of Pulmonary and Critical Care Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Wenju Lu
- Guangzhou Institute of Respiratory Diseases, State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, Guangdong, China
- Department of Laboratory Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, Guangdong, China
- * E-mail: (WL); (JW)
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McEvoy JD, Kossatz U, Malek N, Singer JD. Constitutive turnover of cyclin E by Cul3 maintains quiescence. Mol Cell Biol 2007; 27:3651-66. [PMID: 17339333 PMCID: PMC1899986 DOI: 10.1128/mcb.00720-06] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Two distinct pathways for the degradation of mammalian cyclin E have previously been described. One pathway is induced by cyclin E phosphorylation and is dependent on the Cul1/Fbw7-based E3 ligase. The other pathway is dependent on the Cul3-based E3 ligase, but the mechanistic details of this pathway have yet to be elucidated. To establish the role of Cul3 in the degradation of cyclin E in vivo, we created a conditional knockout of the Cul3 gene in mice. Interestingly, the biallelic loss of Cul3 in primary fibroblasts derived from these mice results in increased cyclin E expression and reduced cell viability, paralleling the loss of Cul3 protein expression. Cell cycle analysis of viable, Cul3 hypomorphic cells shows that decreasing the levels of Cul3 increases both cyclin E protein levels and the number of cells in S phase. In order to examine the role of Cul3 in an in vivo setting, we determined the effect of deletion of the Cul3 gene in liver. This gene deletion resulted in a dramatic increase in cyclin E levels as well as an increase in cell size and ploidy. The results we report here show that the constitutive degradation pathway for cyclin E that is regulated by the Cul3-based E3 ligase is essential to maintain quiescence in mammalian cells.
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Affiliation(s)
- Justina D McEvoy
- Department of Molecular Biology, Cell Biology and Biochemistry and Center for Genomics and Proteomics, Brown University, 70 Ship Street, Box G-E337, Providence, RI 02903, USA
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Polinko ES, Strome S. Depletion of a Cks homolog in C. elegans embryos uncovers a post-metaphase role in both meiosis and mitosis. Curr Biol 2000; 10:1471-4. [PMID: 11102813 DOI: 10.1016/s0960-9822(00)00808-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In eukaryotic cells, the key regulators of cell-cycle transitions are the cyclin-dependent kinases (CDKs). The best studied CDK is a component of the M-phase promoting factor (MPF), which promotes entry into and progression through meiosis and mitosis. One of the enduring mysteries of the MPF complex has been the role of Cks/Suc1, a highly conserved member of the cell-cycle machinery in eukaryotes [1,2]. Cks has been proposed to be involved in activation of MPF [3], general interactions of MPF with its mitotic substrates [4] and/or inactivation of MPF [5,6]. We identified two Cks homologs in the genome of Caenorhabditis elegans and used RNA-mediated interference (RNAi) to investigate their roles in development. Whereas cks-2(RNAi) embryos display no apparent defects, cks-1(RNAi) embryos display defects in both meiosis and mitosis. Specifically, cks-1(RNAi) embryos fail to exit M phase properly. We propose that CKS-1 has an essential role in the inactivation of MPF during early C. elegans embryogenesis.
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Affiliation(s)
- E S Polinko
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
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Dealy MJ, Nguyen KV, Lo J, Gstaiger M, Krek W, Elson D, Arbeit J, Kipreos ET, Johnson RS. Loss of Cul1 results in early embryonic lethality and dysregulation of cyclin E. Nat Genet 1999; 23:245-8. [PMID: 10508527 DOI: 10.1038/13886] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The sequential timing of cell-cycle transitions is primarily governed by the availability and activity of key cell-cycle proteins. Recent studies in yeast have identified a class of ubiquitin ligases (E3 enzymes) called SCF complexes, which regulate the abundance of proteins that promote and inhibit cell-cycle progression at the G1-S phase transition. SCF complexes consist of three invariable components, Skp1, Cul-1 (Cdc53 in yeast) and Rbx1, and a variable F-box protein that recruits a specific cellular protein to the ubquitin pathway for degradation. To study the role of Cul-1 in mammalian development and cell-cycle regulation, we generated mice deficient for Cul1 and analysed null embryos and heterozygous cell lines. We show that Cul1 is required for early mouse development and that Cul1 mutants fail to regulate the abundance of the G1 cyclin, cyclin E (encoded by Ccne), during embryogenesis.
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Affiliation(s)
- M J Dealy
- Department of Biology, University of California, San Diego, California 92093-0366, USA
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