1
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Sionov RV, Ahdut-HaCohen R. A Supportive Role of Mesenchymal Stem Cells on Insulin-Producing Langerhans Islets with a Specific Emphasis on The Secretome. Biomedicines 2023; 11:2558. [PMID: 37761001 PMCID: PMC10527322 DOI: 10.3390/biomedicines11092558] [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: 08/15/2023] [Revised: 09/06/2023] [Accepted: 09/14/2023] [Indexed: 09/29/2023] Open
Abstract
Type 1 Diabetes (T1D) is a chronic autoimmune disease characterized by a gradual destruction of insulin-producing β-cells in the endocrine pancreas due to innate and specific immune responses, leading to impaired glucose homeostasis. T1D patients usually require regular insulin injections after meals to maintain normal serum glucose levels. In severe cases, pancreas or Langerhans islet transplantation can assist in reaching a sufficient β-mass to normalize glucose homeostasis. The latter procedure is limited because of low donor availability, high islet loss, and immune rejection. There is still a need to develop new technologies to improve islet survival and implantation and to keep the islets functional. Mesenchymal stem cells (MSCs) are multipotent non-hematopoietic progenitor cells with high plasticity that can support human pancreatic islet function both in vitro and in vivo and islet co-transplantation with MSCs is more effective than islet transplantation alone in attenuating diabetes progression. The beneficial effect of MSCs on islet function is due to a combined effect on angiogenesis, suppression of immune responses, and secretion of growth factors essential for islet survival and function. In this review, various aspects of MSCs related to islet function and diabetes are described.
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Affiliation(s)
- Ronit Vogt Sionov
- The Institute of Biomedical and Oral Research (IBOR), Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel
| | - Ronit Ahdut-HaCohen
- Department of Medical Neurobiology, Institute of Medical Research, Hadassah Medical School, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel;
- Department of Science, The David Yellin Academic College of Education, Jerusalem 9103501, Israel
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2
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Luo Y, Wu Y, Huang H, Yi N, Chen Y. Emerging role of BAD and DAD1 as potential targets and biomarkers in cancer. Oncol Lett 2021; 22:811. [PMID: 34671425 PMCID: PMC8503815 DOI: 10.3892/ol.2021.13072] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 09/01/2021] [Indexed: 12/28/2022] Open
Abstract
As key regulators of apoptosis, BAD and defender against apoptotic cell death 1 (DAD1) are associated with cancer initiation and progression. Multiple studies have demonstrated that BAD and DAD1 serve critical roles in several types of cancer and perform various functions, such as participating in cellular apoptosis, invasion and chemosensitivity, as well as their role in diagnostic/prognostic judgement, etc. Investigating the detailed mechanisms of the cancerous effects of the two proteins will contribute to enriching the options for targeted therapy, and may improve clinical treatment of cancer. The present review summarizes research advances regarding the associations of BAD and DAD1 with cancer, and a hypothesis on the feasible relationship and interaction mechanism between the two proteins is proposed. Furthermore, the present review highlights the potential of the two proteins as therapeutic targets and valuable diagnostic and prognostic biomarkers.
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Affiliation(s)
- Yulou Luo
- First Clinical Medical College, Xinjiang Medical University, Urumqi, Xinjiang Uyghur Autonomous Region 830054, P.R. China
| | - You Wu
- Nursing College, Binzhou Medical University, Binzhou, Shandong 264003, P.R. China
| | - Hai Huang
- First Clinical Medical College, Xinjiang Medical University, Urumqi, Xinjiang Uyghur Autonomous Region 830054, P.R. China
| | - Na Yi
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xinjiang Medical University, Urumqi, Xinjiang Uyghur Autonomous Region 830017, P.R. China
| | - Yan Chen
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xinjiang Medical University, Urumqi, Xinjiang Uyghur Autonomous Region 830017, P.R. China
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3
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DEMİR EKŞİ D, YILMAZ E, AKIN Y, USTA MF, BAŞAR MM, KAHRAMAN S, ERMAN M, ALPER ÖM. Copy Number Variation Analysis in Turkish Patients with Congenital Bilateral Absence of Vas Deferens. ACTA MEDICA ALANYA 2021. [DOI: 10.30565/medalanya.966940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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4
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Zhang Y, Yu M, Dong J, Wu Y, Tian W. Identification of Novel Adipokines through Proteomic Profiling of Small Extracellular Vesicles Derived from Adipose Tissue. J Proteome Res 2020; 19:3130-3142. [PMID: 32597661 DOI: 10.1021/acs.jproteome.0c00131] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Adipose tissue is regarded as a true endocrine organ that releases adipokines to regulate distant targets. Besides the well-studied secretory adipokines, the adipokines carried by small extracellular vesicles derived from adipose tissue (sEV-AT) have not been completely characterized yet. In this study, we conducted a complementary protein profiling on sEV-AT with label-free quantitative proteomic analysis (project accession: PXD013270). A total of 2607 sEV-AT proteins were identified, among which 328 proteins had been annotated as adipokines. Three undefined adipokine candidates (NPM3, STEAP3, and DAD1) were selected for further validation. These three proteins were expressed in both white and brown adipose tissues and upregulated during adipogenic differentiation in both 3T3-L1 cells and adipose-derived stromal/stem cells (ASCs). Expressions of NPM3 and DAD1 in sEV-AT were significantly decreased in obese subjects compared with lean controls, while obesity could not alter the expression of STEAP3. Our profiling study of the sEV-AT proteins expanded the list of adipokines and highlighted the pivotal role of adipokines specifically carried by sEVs in the regulation of multiple biological processes within adipose tissue.
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Affiliation(s)
- Yan Zhang
- State Key Laboratory of Oral Disease, Engineering Research Center of Oral Translational Medicine, Ministry of Education, West China School of Stomatology, Sichuan University, Chengdu 610041, China.,National Engineering Laboratory for Oral Regenerative Medicine, West China School of Stomatology, Sichuan University, Chengdu 610041, China.,Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Mei Yu
- State Key Laboratory of Oral Disease, Engineering Research Center of Oral Translational Medicine, Ministry of Education, West China School of Stomatology, Sichuan University, Chengdu 610041, China.,National Engineering Laboratory for Oral Regenerative Medicine, West China School of Stomatology, Sichuan University, Chengdu 610041, China
| | - Jia Dong
- State Key Laboratory of Oral Disease, Engineering Research Center of Oral Translational Medicine, Ministry of Education, West China School of Stomatology, Sichuan University, Chengdu 610041, China.,National Engineering Laboratory for Oral Regenerative Medicine, West China School of Stomatology, Sichuan University, Chengdu 610041, China.,Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Yue Wu
- State Key Laboratory of Oral Disease, Engineering Research Center of Oral Translational Medicine, Ministry of Education, West China School of Stomatology, Sichuan University, Chengdu 610041, China.,National Engineering Laboratory for Oral Regenerative Medicine, West China School of Stomatology, Sichuan University, Chengdu 610041, China.,Department of Oral and Maxillofacial Surgery, Xiangya School of Stomatology, Central South University, Changsha 410083, China
| | - Weidong Tian
- State Key Laboratory of Oral Disease, Engineering Research Center of Oral Translational Medicine, Ministry of Education, West China School of Stomatology, Sichuan University, Chengdu 610041, China.,National Engineering Laboratory for Oral Regenerative Medicine, West China School of Stomatology, Sichuan University, Chengdu 610041, China.,Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
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5
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Beaugelin I, Chevalier A, D'Alessandro S, Ksas B, Havaux M. Endoplasmic reticulum-mediated unfolded protein response is an integral part of singlet oxygen signalling in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 102:1266-1280. [PMID: 31975462 DOI: 10.1111/tpj.14700] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Revised: 01/07/2020] [Accepted: 01/13/2020] [Indexed: 05/19/2023]
Abstract
Singlet oxygen (1 O2 ) is a by-product of photosynthesis that triggers a signalling pathway leading to stress acclimation or to cell death. By analyzing gene expressions in a 1 O2 -overproducing Arabidopsis mutant (ch1) under different light regimes, we show here that the 1 O2 signalling pathway involves the endoplasmic reticulum (ER)-mediated unfolded protein response (UPR). ch1 plants in low light exhibited a moderate activation of UPR genes, in particular bZIP60, and low concentrations of the UPR-inducer tunicamycin enhanced tolerance to photooxidative stress, together suggesting a role for UPR in plant acclimation to low 1 O2 levels. Exposure of ch1 to high light stress ultimately leading to cell death resulted in a marked upregulation of the two UPR branches (bZIP60/IRE1 and bZIP28/bZIP17). Accordingly, mutational suppression of bZIP60 and bZIP28 increased plant phototolerance, and a strong UPR activation by high tunicamycin concentrations promoted high light-induced cell death. Conversely, light acclimation of ch1 to 1 O2 stress put a limitation in the high light-induced expression of UPR genes, except for the gene encoding the BIP3 chaperone, which was selectively upregulated. BIP3 deletion enhanced Arabidopsis photosensitivity while plants treated with a chemical chaperone exhibited enhanced phototolerance. In conclusion, 1 O2 induces the ER-mediated UPR response that fulfils a dual role in high light stress: a moderate UPR, with selective induction of BIP3, is part of the acclimatory response to 1 O2 , and a strong activation of the whole UPR is associated with cell death.
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Affiliation(s)
- Inès Beaugelin
- Aix-Marseille University, CNRS, CEA, 13108, Saint-Paul-lez-Durance, France
| | - Anne Chevalier
- Aix-Marseille University, CNRS, CEA, 13108, Saint-Paul-lez-Durance, France
| | | | - Brigitte Ksas
- Aix-Marseille University, CNRS, CEA, 13108, Saint-Paul-lez-Durance, France
| | - Michel Havaux
- Aix-Marseille University, CNRS, CEA, 13108, Saint-Paul-lez-Durance, France
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6
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Transcriptional regulation of seven cyadox-related genes mainly activated by PI3K and NF-кB signaling pathways in PK-15 cells. Res Vet Sci 2020; 131:232-243. [PMID: 32417693 DOI: 10.1016/j.rvsc.2020.04.024] [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: 12/16/2019] [Revised: 03/24/2020] [Accepted: 04/29/2020] [Indexed: 11/21/2022]
Abstract
Cyadox, a new antibacterial agent as the quinoxaline-1, 4-dioxides, has a good antibacterial and growth-promoting effect, and has the advantages of lower toxicity, adequate safety and faster absorption. Seven differential expressed genes (DEGs) induced by cyadox were screened in swine liver tissues, including Insulin-like Growth Factor-1 (IGF-1), Epidermal Growth Factor (EGF), Poly ADP-ribose polymerase (PARP), the Defender Against Apoptotic Death 1 (DAD1), Complement Component 3 (C3), Transketolase (TK) and cyadox-related novel gene (CRNG). To elucidate the signal mechanism that cyadox altered these genes expression, the time-effect relationship and signaling pathways related to 7 DEGs induced by cyadox were determined in Porcine Kidney-15 (PK-15) cells by RT-qPCR and the application of various signal pathway inhibitors. The phosphorylation levels of signal factors in PK-15 cells were detected by Western blot. The analyses demonstrated that, the mRNA expressions of 7 DEGs were significantly enhanced by cyadox mainly through the phosphoinositide 3-kinase (PI3K) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-кB) signaling pathways in PK-15 cells. Furthermore, EGF might be the early response gene of cyadox to activate downstream signaling pathways and regulates the expression of other related genes or directly exerting biological effects. In brief, cyadox mainly regulates the expression of these 7 genes by PI3K and NF-кB signaling pathways to exert it's antibacterial and growth-promoting activity in PK-15 cells.
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7
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Zhou Z, Li Y, Kuang M, Wang X, Jia Q, Cao J, Hu J, Wu S, Wang Z, Xiao J. The CD24 + cell subset promotes invasion and metastasis in human osteosarcoma. EBioMedicine 2020; 51:102598. [PMID: 31901872 PMCID: PMC6948162 DOI: 10.1016/j.ebiom.2019.102598] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 12/06/2019] [Accepted: 12/09/2019] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Osteosarcoma is the most common primary aggressive bone tumor affecting children and young adolescents. Metastases are often resistant to conventional chemotherapy and mean short-term survival. Development of valuable diagnostic indicators and targeting agents will have important implications for clinical diagnosis by the identification and characterization of molecules that contribute to its aggressive behavior. METHODS We examined differential expression levels of common stem cell markers in osteosarcoma parental and sphere cells. In addition, we further analyzed the changes of candidate common stem cell markers before and after in vitro chemotherapy of osteosarcoma cells. The biological functions of CD24+ subpopulation in osteosarcoma such as proliferation, migration, invasion, tumorigenesis and metastasis were systematically investigated, and the correlations of CD24 levels with prognosis in patients with osteosarcoma were analyzed. FINDINGS CD24+ Cells presented characteristics of TICs and resist drug-induced apoptosis. The prevention of tumor formation and metastasis by CD24 knockdown highlights the potential of CD24 as a therapeutic target for osteosarcoma. Moreover, the levels of CD24 in osteosarcoma samples were significantly correlated with the prognosis of patients. INTERPRETATION CD24+ cell subset played an important role in osteosarcoma invasion and metastasis. FUNDING National Natural Science Foundation of China (No.81772857); Shanghai Science and Technology Commission (18140902000); Shanghai Municipal Health Commission (2017ZZ01017; 17411950301).
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Affiliation(s)
- Zhenhua Zhou
- Department of Orthopaedic Oncology, Changzheng Hospital, Naval Medical University (The Second Military Medical University), Shanghai, 200003,China
| | - Yan Li
- Cancer Institute, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, 200032,China
| | - Muyu Kuang
- Huadong Hospital, Fudan University, Shanghai,200040, China
| | - Xudong Wang
- Department of Orthopaedic Oncology, Changzheng Hospital, Naval Medical University (The Second Military Medical University), Shanghai, 200003,China
| | - Qi Jia
- Department of Orthopaedic Oncology, Changzheng Hospital, Naval Medical University (The Second Military Medical University), Shanghai, 200003,China
| | - Jiashi Cao
- Department of Orthopaedic Oncology, Changzheng Hospital, Naval Medical University (The Second Military Medical University), Shanghai, 200003,China
| | - Jingjing Hu
- Clinical Research Center, Changhai Hospital, Naval Medical University (The Second Military Medical University), Shanghai 200433, China
| | - Sujia Wu
- Department of Orthopedics, Nanjing General Hospital of Nanjing Military Region, Nanjing, Jiangsu, 210002, China
| | - Zhiwei Wang
- Department of Orthopedics, Changhai Hospital, Naval Medical University (The Second Military Medical University), Shanghai, 200433, China.
| | - Jianru Xiao
- Department of Orthopaedic Oncology, Changzheng Hospital, Naval Medical University (The Second Military Medical University), Shanghai, 200003,China.
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8
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Kanaki N, Matsuda A, Dejima K, Murata D, Nomura KH, Ohkura T, Gengyo-Ando K, Yoshina S, Mitani S, Nomura K. UDP-N-acetylglucosamine-dolichyl-phosphate N-acetylglucosaminephosphotransferase is indispensable for oogenesis, oocyte-to-embryo transition, and larval development of the nematode Caenorhabditis elegans. Glycobiology 2019; 29:163-178. [PMID: 30445613 DOI: 10.1093/glycob/cwy104] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 11/09/2018] [Indexed: 12/13/2022] Open
Abstract
N-linked glycosylation of proteins is the most common post-translational modification of proteins. The enzyme UDP-N-acetylglucosamine-dolichyl-phosphate N-acetylglucosaminephosphotransferase (DPAGT1) catalyses the first step of N-glycosylation, and DPAGT1 knockout is embryonic lethal in mice. In this study, we identified the sole orthologue (algn-7) of the human DPAGT1 in the nematode C. elegans. The gene activity was disrupted by RNAi and deletion mutagenesis, which resulted in larval lethality, defects in oogenesis and oocyte-to-embryo transition. Endomitotic oocytes, abnormal fusion of pronuclei, abnormal AB cell rotation, disruption of permeation barriers of eggs, and abnormal expression of chitin and chitin synthase in oocytes and eggs were the typical phenotypes observed. The results indicate that N-glycosylation is indispensable for these processes. We further screened an N-glycosylated protein database of C. elegans, and identified 456 germline-expressed genes coding N-glycosylated proteins. By examining RNAi phenotypes, we identified five germline-expressed genes showing similar phenotypes to the algn-7 (RNAi) animals. They were ribo-1, stt-3, ptc-1, ptc-2, and vha-19. We identified known congenital disorders of glycosylation (CDG) genes (ribo-1 and stt-3) and a recently found CDG gene (vha-19). The results show that phenotype analyses using the nematode could be a powerful tool to detect new CDG candidate genes and their associated gene networks.
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Affiliation(s)
- Nanako Kanaki
- Department of Systems Life Sciences, Kyushu University Graduate School, Fukuoka, Japan
| | - Ayako Matsuda
- Department of Systems Life Sciences, Kyushu University Graduate School, Fukuoka, Japan
| | - Katsufumi Dejima
- Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan.,Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Daisuke Murata
- Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan
| | - Kazuko H Nomura
- Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan
| | - Takashi Ohkura
- Department of Reproductive Biology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, Japan
| | - Keiko Gengyo-Ando
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Sawako Yoshina
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Shohei Mitani
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Kazuya Nomura
- Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan
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9
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Cornejo-Corona I, Thapa HR, Browne DR, Devarenne TP, Lozoya-Gloria E. Stress responses of the oil-producing green microalga Botryococcus braunii Race B. PeerJ 2016; 4:e2748. [PMID: 27957393 PMCID: PMC5144741 DOI: 10.7717/peerj.2748] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 11/03/2016] [Indexed: 11/20/2022] Open
Abstract
Plants react to biotic and abiotic stresses with a variety of responses including the production of reactive oxygen species (ROS), which may result in programmed cell death (PCD). The mechanisms underlying ROS production and PCD have not been well studied in microalgae. Here, we analyzed ROS accumulation, biomass accumulation, and hydrocarbon production in the colony-forming green microalga Botryococcus braunii in response to several stress inducers such as NaCl, NaHCO3, salicylic acid (SA), methyl jasmonate, and acetic acid. We also identified and cloned a single cDNA for the B. braunii ortholog of the Arabidopsis gene defender against cell death 1 (DAD1), a gene that is directly involved in PCD regulation. The function of B. braunii DAD1 was assessed by a complementation assay of the yeast knockout line of the DAD1 ortholog, oligosaccharyl transferase 2. Additionally, we found that DAD1 transcription was induced in response to SA at short times. These results suggest that B. braunii responds to stresses by mechanisms similar to those in land plants and other organisms.
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Affiliation(s)
- Ivette Cornejo-Corona
- Genetic Engineering, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Unidad Irapuato , Irapuato , Guanajuato , Mexico
| | - Hem R Thapa
- Department of Biochemistry and Biophysics, Texas A&M University , College Station , TX , United States
| | - Daniel R Browne
- Department of Biochemistry and Biophysics, Texas A&M University , College Station , TX , United States
| | - Timothy P Devarenne
- Department of Biochemistry and Biophysics, Texas A&M University , College Station , TX , United States
| | - Edmundo Lozoya-Gloria
- Genetic Engineering, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Unidad Irapuato , Irapuato , Guanajuato , Mexico
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10
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Mohorko E, Glockshuber R, Aebi M. Oligosaccharyltransferase: the central enzyme of N-linked protein glycosylation. J Inherit Metab Dis 2011; 34:869-78. [PMID: 21614585 DOI: 10.1007/s10545-011-9337-1] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 04/01/2011] [Accepted: 04/07/2011] [Indexed: 01/07/2023]
Abstract
N-linked glycosylation is one of the most abundant modifications of proteins in eukaryotic organisms. In the central reaction of the pathway, oligosaccharyltransferase (OST), a multimeric complex located at the membrane of the endoplasmic reticulum, transfers a preassembled oligosaccharide to selected asparagine residues within the consensus sequence asparagine-X-serine/threonine. Due to the high substrate specificity of OST, alterations in the biosynthesis of the oligosaccharide substrate result in the hypoglycosylation of many different proteins and a multitude of symptoms observed in the family of congenital disorders of glycosylation (CDG) type I. This review covers our knowledge of human OST and describes enzyme composition. The Stt3 subunit of OST harbors the catalytic center of the enzyme, but the function of the other, highly conserved, subunits are less well defined. Some components seem to be involved in the recognition and utilization of glycosylation sites in specific glycoproteins. Indeed, mutations in the subunit paralogs N33/Tusc3 and IAP do not yield the pleiotropic phenotypes typical for CDG type I but specifically result in nonsyndromic mental retardation, suggesting that the oxidoreductase activity of these subunits is required for glycosylation of a subset of proteins essential for brain development.
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Affiliation(s)
- Elisabeth Mohorko
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zürich, Schafmatt 20, CH, 8093, Zürich, Switzerland
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11
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Cacas JL. Devil inside: does plant programmed cell death involve the endomembrane system? PLANT, CELL & ENVIRONMENT 2010; 33:1453-1473. [PMID: 20082668 DOI: 10.1111/j.1365-3040.2010.02117.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Eukaryotic cells have to constantly cope with environmental cues and integrate developmental signals. Cell survival or death is the only possible outcome. In the field of animal biology, tremendous efforts have been put into the understanding of mechanisms underlying cell fate decision. Distinct organelles have been proven to sense a broad range of stimuli and, if necessary, engage cell death signalling pathway(s). Over the years, forward and reverse genetic screens have uncovered numerous regulators of programmed cell death (PCD) in plants. However, to date, molecular networks are far from being deciphered and, apart from the autophagic compartment, no organelles have been assigned a clear role in the regulation of cellular suicide. The endomembrane system (ES) seems, nevertheless, to harbour a significant number of cell death mediators. In this review, the involvement of this system in the control of plant PCD is discussed in-depth, as well as compared and contrasted with what is known in animal and yeast systems.
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Affiliation(s)
- Jean-Luc Cacas
- Institut de Recherche pour le Développement, Equipe 2, Mécanismes des Résistances, Montpellier Cedex 5, France.
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12
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Bae JS, Cheong HS, Park BL, Kim LH, Park TJ, Kim JY, Pasaje CFA, Lee JS, Cui T, Inoue I, Shin HD. Genome-wide association analysis of copy number variations in subarachnoid aneurysmal hemorrhage. J Hum Genet 2010; 55:726-30. [PMID: 20703242 DOI: 10.1038/jhg.2010.97] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Subarachnoid aneurysmal hemorrhage (SAH) due to cerebral aneurysm rupture is a very serious disease resulting in high mortality rate. It has been known that genetic factors are involved in the risk of SAH. A recent breakthrough in genomic variation called copy number variation (CNV) has been revealed to be involved in risks of human diseases. In this study, we hypothesized that CNVs can predict the risk of SAH. We used the Illumina HumanHap300 BeadChip (317 503 markers) to genotype 497 individuals in a Japanese population. Furthermore, individual CNVs were identified using signal and allelic intensities. The genetic effect of CNV on the risk of SAH was evaluated using multivariate logistic regression controlling for age and gender in 187 common CNV regions (frequency >1%). From a total of 4574 individual CNVs identified in this study (9.7 CNVs per individual), we were able to discover 1644 unique CNV regions containing 1232 genes. The identified variations were validated using visual examination of the genoplot image, overlapping analysis with the Database of Genomic Variants (73.2%), CNVpartition (72.4%) and quantitative PCR. Interestingly, two CNV regions, chr4:153210505-153212191 (deletion, 4q31.3, P=0.0005, P(corr) (corrected P-value)=0.04) and chr10:6265006-6267388 (duplication, 10p15.1, P=0.0006, P(corr)=0.05), were significantly associated with the risk of SAH after multiple testing corrections. Our results suggest that the newly identified CNV regions may contribute to SAH disease susceptibility.
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Affiliation(s)
- Joon Seol Bae
- Laboratory of Genomic Diversity, Department of Life Science, Sogang University, Shinsu-dong, Mapo-gu, Seoul, Republic of Korea
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13
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Wang L, Wu X. Identification of differentially expressed genes in lipopolysaccharide-stimulated yellow grouper Epinephelus awoara spleen. FISH & SHELLFISH IMMUNOLOGY 2007; 23:354-63. [PMID: 17210258 DOI: 10.1016/j.fsi.2006.11.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 11/20/2006] [Accepted: 11/20/2006] [Indexed: 05/13/2023]
Abstract
A subtracted cDNA library from lipopolysaccharide (LPS)-stimulated Epinephelus awoara spleen was constructed using the suppression subtractive hybridization (SSH). Random clones (209) were selected and sequenced. After assembling, 36 contigs and 56 singlets (accession numbers: EB410743-EB410834) were finally obtained, some of which were immune-related genes. A reverse transcription-polymerase chain reaction (RT-PCR) analysis of the expression patterns of eight transcripts showed that seven of them were up-regulated after 24 h of LPS stimulation. Furthermore, full-length cDNAs of homologues of defender against cell death 1 (DAD1) and allograft inflammatory factor-1 (AIF-1) were obtained by RACE-PCR.
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Affiliation(s)
- Li Wang
- Laboratory of Marine Life Science and Technology, College of Animal Sciences, Zhejiang University, 268 Kaixuan Road, Hangzhou, Zhejiang 310029, China
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14
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Gomos-Klein J, Harrow F, Alarcón J, Ortiz BD. CTCF-Independent, but Not CTCF-Dependent, Elements Significantly Contribute to TCR-α Locus Control Region Activity. THE JOURNAL OF IMMUNOLOGY 2007; 179:1088-95. [PMID: 17617601 DOI: 10.4049/jimmunol.179.2.1088] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The mouse TCRalpha/TCRdelta/Dad1 gene locus bears a locus control region (LCR) that drives high-level, position-independent, thymic transgene expression in chromatin. It achieves this through DNA sequences that enhance transcription and protect transgene expression from integration site-dependent position effects. The former activity maps to a classical enhancer region (Ealpha). In contrast, the elements supporting the latter capacity that suppresses position effects are incompletely understood. Such elements likely play important roles in their native locus and may resemble insulator/boundary sequences. Insulators support enhancer blocking and/or chromatin barrier activity. Most vertebrate enhancer-blocking insulators are dependent on the CTCF transcription factor and its cognate DNA binding site. However, studies have also revealed CTCF-independent enhancer blocking and barrier insulator activity in the vertebrate genome. The TCRalpha LCR contains a CTCF-dependent and multiple CTCF-independent enhancer-blocking regions whose roles in LCR activity are unknown. Using randomly integrated reporter transgenes in mice, we find that the CTCF region plays a very minor role in LCR function. In contrast, we report the in vivo function of two additional downstream elements located in the region of the LCR that supports CTCF-independent enhancer-blocking activity in cell culture. Internal deletion of either of these elements significantly impairs LCR activity. These results reveal that the position-effect suppression region of the TCRalpha LCR harbors an array of CTCF-independent, positive-acting gene regulatory elements, some of which share characteristics with barrier-type insulators. These elements may help manage the separate regulatory programs of the TCRalpha and Dad1 genes.
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Affiliation(s)
- Janette Gomos-Klein
- Department of Biological Sciences, City University of New York, Hunter College, New York, NY 10021, USA
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15
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Heinitz K, Beck M, Schliebs R, Perez-Polo JR. Toxicity mediated by soluble oligomers of beta-amyloid(1-42) on cholinergic SN56.B5.G4 cells. J Neurochem 2006; 98:1930-45. [PMID: 16945109 DOI: 10.1111/j.1471-4159.2006.04015.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Alzheimer's disease (AD) is characterized by cholinergic dysfunction and progressive basal forebrain cell loss which has been assumed to be as a result of the extensive accumulation of beta-amyloid (Abeta). In addition to Abeta fibrillar assemblies, there are pre-fibrillar forms that have been shown to be neurotoxic, although their role in cholinergic degeneration is still not known. Using the cholinergic cell line SN56.B5.G4, we investigated the effect of different Abeta(1-42) aggregates on cell viability. In our model, only soluble oligomeric but not fibrillar Abeta(1-42) forms induced toxicity in cholinergic cells. To determine whether the neurotoxicity of oligomeric Abeta(1-42) was caused by its oxidative potential, we performed microarray analysis of SN56.B5.G4 cells treated either with oligomeric Abeta(1-42) or H(2)O(2). We showed that genes affected by Abeta(1-42) differed from those affected by non-specific oxidative stress. Many of the genes affected by Abeta(1-42) were present in the endoplasmic reticulum (ER), Golgi apparatus and/or otherwise involved in protein modification and degradation (chaperones, ATF6), indicating a possible role for ER-mediated stress in Abeta-mediated toxicity. Moreover, a number of genes, which are known to be involved in AD (clusterin, Slc18a3), were identified. This study provides important leads for the understanding of oligomeric Abeta(1-42) toxicity in cholinergic cells, which may account in part for cholinergic degeneration in AD.
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Affiliation(s)
- Katrin Heinitz
- Paul Flechsig Institute for Brain Research, Department of Neurochemistry, University of Leipzig, Leipzig, Germany
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16
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Hauptmann P, Riel C, Kunz-Schughart LA, Fröhlich KU, Madeo F, Lehle L. Defects in N-glycosylation induce apoptosis in yeast. Mol Microbiol 2006; 59:765-78. [PMID: 16420350 DOI: 10.1111/j.1365-2958.2005.04981.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
N-glycosylation in the endoplasmic reticulum is an essential protein modification and highly conserved in evolution from yeast to man. Defects of N-glycosylation in humans lead to congenital disorders. The pivotal step of this pathway is the transfer of the evolutionarily conserved lipid-linked core-oligosaccharide to the nascent polypeptide chain, catalysed by the oligosaccharyltransferase. One of its nine subunits, Ost2, has homology to DAD1, originally characterized in hamster cells as a defender against apoptotic death. Here we show that ost mutants, such as ost2 and wbp1-1, display morphological and biochemical features of apoptosis upon induction of the glycosylation defect. We observe nuclear condensation, DNA fragmentation as well as externalization of phosphatidylserine. We also demonstrate induction of caspase-like activity, both determined by flow cytometric analysis and in cell-free extracts. Similarly, the N-glycosylation inhibitor tunicamycin in combination with elevated temperature is able to challenge the apoptotic cascade. Heterologous expression of anti-apoptotic human Bcl-2 diminishes caspase activation, improves survival of cells and suppresses the temperature-sensitive growth defect of wbp1-1. Furthermore, accumulation of reactive oxygen species occurs in response to defective glycosylation. As deletion of the metacaspase YCA1 does not seem to abrogate glycosylation-induced apoptosis, we postulate a different proteolytic process to be involved in this death pathway.
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Affiliation(s)
- Peter Hauptmann
- Lehrstuhl für Zellbiologie und Pflanzenphysiologie, Universität Regensburg, Regensburg, Germany
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17
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Kelleher DJ, Gilmore R. An evolving view of the eukaryotic oligosaccharyltransferase. Glycobiology 2005; 16:47R-62R. [PMID: 16317064 DOI: 10.1093/glycob/cwj066] [Citation(s) in RCA: 401] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Asparagine-linked glycosylation (ALG) is one of the most common protein modification reactions in eukaryotic cells, as many proteins that are translocated across or integrated into the rough endoplasmic reticulum (RER) carry N-linked oligosaccharides. Although the primary focus of this review will be the structure and function of the eukaryotic oligosaccharyltransferase (OST), key findings provided by the analysis of the archaebacterial and eubacterial OST homologues will be reviewed, particularly those that provide insight into the recognition of donor and acceptor substrates. Selection of the fully assembled donor substrate will be considered in the context of the family of human diseases known as congenital disorders of glycosylation (CDG). The yeast and vertebrate OST are surprisingly complex hetero-oligomeric proteins consisting of seven or eight subunits (Ost1p, Ost2p, Ost3p/Ost6p, Ost4p, Ost5p, Stt3p, Wbp1p, and Swp1p in yeast; ribophorin I, DAD1, N33/IAP, OST4, STT3A/STT3B, Ost48, and ribophorin II in mammals). Recent findings from several laboratories have provided overwhelming evidence that the STT3 subunit is critical for catalytic activity. Here, we will consider the evolution and assembly of the eukaryotic OST in light of recent genomic evidence concerning the subunit composition of the enzyme in diverse eukaryotes.
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Affiliation(s)
- Daniel J Kelleher
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605-2324, USA
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18
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Lavieu G, Frénoy JP, Codogno P, Botti J. Defect of N-glycosylation is not directly related to congenital disorder of glycosylation Ia fibroblast sensitivity to staurosporine-induced cell death. Pediatr Res 2005; 58:254-7. [PMID: 16085795 DOI: 10.1203/01.pdr.0000169962.02462.c0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Congenital disorder of glycosylation Ia (CDGIa) is an autosomal recessive disease that is caused by mutations in the gene PMM2 encoding phosphomannomutase, an enzyme that synthesizes mannose-1-phosphate, an important intermediate for the N-glycan biosynthesis. Here, we investigated the susceptibility of CDGIa fibroblasts to cell death induction. CDGIa fibroblasts were more sensitive than control fibroblasts to staurosporine-induced apoptosis. Supplementation with mannose, which corrects N-glycosylation in CDGIa fibroblasts, did not abrogate their higher sensitivity to staurosporine. These results show that the sensitivity of CDGIa fibroblasts to apoptosis is not directly related to their defective N-glycosylation.
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Affiliation(s)
- Grégory Lavieu
- INSERM Unité 504, Bâtiment INSERM, 94807 Villejuif Cedex, France
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19
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Gomez-Bougie P, Bataille R, Amiot M. Endogenous association of Bim BH3-only protein with Mcl-1, Bcl-xL and Bcl-2 on mitochondria in human B cells. Eur J Immunol 2005; 35:971-6. [PMID: 15724238 DOI: 10.1002/eji.200425878] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Bim is an essential regulator of lymphoid system homeostasis and appears essential for B cell apoptosis induction. The mechanism by which Bim isoforms are held in an inactive form remains poorly documented in normal B cells. In the current study, we demonstrated that in normal tonsil B cells the three major Bim isoforms are strongly associated with the anti-apoptotic Bcl-2 family members Mcl-1, Bcl-2 and Bcl-x(L). On the other hand, only a weak association of BimEL and L with the dynein LC8 chain has been found. In addition, there is no free Bim in normal B cells. Moreover, subcellular fractionation demonstrated that Bim and the anti-apoptotic counterparts are localized preferentially in the mitochondria-rich fraction. The fact that most Bim was found in this fraction supports the hypothesis that it is sequestered by anti-apoptotic molecules in mitochondria where its pro-apoptotic activity is controlled. Of interest, BimS is essentially complexed to Mcl-1 and the Mcl-1/Bim complex is the most abundant among the three types of complexes. This supports the idea that this complex is critical for the control of B cell death. In conclusion, these results favor a model in which Bim release from anti-apoptotic proteins is a critical event for initiation of apoptosis.
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Affiliation(s)
- Patricia Gomez-Bougie
- INSERM, UMR601, Département de Recherche en Cancérologie, Equipe 5 labélisée L N C, Institut de Biologie, Nantes, France
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20
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Rosen MB, Wilson VS, Schmid JE, Gray LE. Gene expression analysis in the ventral prostate of rats exposed to vinclozolin or procymidone. Reprod Toxicol 2005; 19:367-79. [PMID: 15686871 DOI: 10.1016/j.reprotox.2004.10.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2004] [Accepted: 10/14/2004] [Indexed: 10/26/2022]
Abstract
Vinclozolin and procymidone are antiandrogens that are thought to share a common androgen receptor (AR) mediated mechanism of action. This assessment is based primarily on morphological, AR binding, and in vitro transcriptional activation studies. Studies designed to evaluate the gene expression profiles induced by these compounds have the potential to provide further information to test this hypothesis. We have used targeted gene arrays to examine gene expression in the ventral prostate (VP) of 100-day old Sprague Dawley male rats exposed to either vinclozolin or procymidone. Animals were castrated and administered silastic implants with or without testosterone. A subset of testosterone treated animals was then dosed with 200 mg/kg of either fungicide in corn oil. Four treatment groups were used: castrated (C), testosterone (T), testosterone+vinclozolin (V), and testosterone+procymidone (P). Tissue from the VP was collected from six animals per group (3 animals per block x 2 blocks) at 20 h and at 4 days after the start of treatment. Total RNA was then isolated and gene expression analyzed using Clontech Atlas Rat 1.2 Toxicology arrays. When compared to group T, similar changes in gene expression were observed in groups C, P and V at both the 20 h and 4 day time points. After 20 h of treatment, 20 genes were similarly affected across these three treatment groups. Down-regulated genes included various molecular chaperones, the 11-kDa diazepam binding inhibitor, cyclin D1, and mitochondrial aspartate aminotransferase. Genes such as the androgen receptor, PTEN, and ERK2 were up-regulated. Three of the down-regulated genes, GRP78 (BiP), Dad1, and mitochondrial aspartate aminotransferase have been previously shown to be directly androgen regulated. Fifty-four genes were affected at 20 h, whereas, 311 genes were altered 4 days after the start of treatment. These observations, in part, may reflect regression of the VP at the later time point. These results support the hypothesis that procymidone and vinclozolin share a common mechanism or mode of action, a critical step in a cumulative risk assessment.
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Affiliation(s)
- Mitchell B Rosen
- United States Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Reproductive Toxicology Division, MD72, Research Triangle Park, NC 27711, USA.
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21
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Magdinier F, Yusufzai TM, Felsenfeld G. Both CTCF-dependent and -independent Insulators Are Found between the Mouse T Cell Receptor α and Dad1 Genes. J Biol Chem 2004; 279:25381-9. [PMID: 15082712 DOI: 10.1074/jbc.m403121200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The T cell rearrangement of the T cell receptor (TCR) genes TCRalpha and delta is specifically regulated by a complex interplay between enhancer elements and chromatin structure. The alpha enhancer is active in T cells and drives TCRalpha recombination in collaboration with a locus control region-like element located downstream of the Calpha gene on mouse chromosome 14. Twelve kb further down-stream lies another gene, Dad1, with a program of expression different from that of TCRalpha. The approximately 6-kb locus control region element lying between them contains multiple regulatory sites with a variety of roles in regulating the two genes. Previous evidence has indicated that among these there are widely distributed regions with enhancer blocking (insulating) activity. We have shown in this report that one of these sites, not previously examined, strongly binds the insulator protein CCTC-binding factor (CTCF) in vitro and in vivo and can function in an enhancer blocking assay. However, other regions within the 6-kb element that also can block enhancers clearly do not harbor CTCF sites and thus must reflect the presence of a previously undetected and distinct vertebrate insulator activity.
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Affiliation(s)
- Frédérique Magdinier
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, Maryland 20892-0504, USA
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22
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Abstract
The epididymis is the site for the transport, maturation, and storage of spermatozoa. Regulation of epididymal structure and function is highly dependent on the ipsilateral testis. At the molecular level, however, few studies have been undertaken to determine which genes are expressed in the epididymis under testicular regulation. The goal of this study was to identify genes for which expression is regulated after orchidectomy, both throughout the epididymis and in a segment-specific manner. Microarrays spotted with 474 rat cDNAs were used to examine gene expression changes over the first 7 d post orchidectomy in the initial segment, caput, corpus, and cauda epididymidis of the adult Brown Norway rat. Using k-means cluster analysis, we show that four patterns of gene expression are activated in each epididymal segment over the first week following orchidectomy. Transient up-regulation of gene expression in the epididymis after orchidectomy is described for the first time. Potential androgen-repressed genes, including Gpx-1, show increased expression in the epididymis after orchidectomy. Several glutathione-S-transferases and calcium-binding proteins decline throughout the epididymis after orchidectomy, indicating that these may be novel androgen-regulated epididymal genes. Other genes coding for metabolism-associated proteins, transporters, and alpha-1 acid glycoprotein show segment-specific regulation in the epididymis after orchidectomy. Finally, we describe the expression of the previously uncharacterized heat shock proteins, and apoptosis-associated genes in the epididymis after orchidectomy. Thus, gene expression in the epididymis is differentially affected over time after orchidectomy. These results provide novel insight into androgen-dependent and segment-specific epididymal function.
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Affiliation(s)
- Nadine Ezer
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
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23
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Looijenga LHJ, Zafarana G, Grygalewicz B, Summersgill B, Debiec-Rychter M, Veltman J, Schoenmakers EFPM, Rodriguez S, Jafer O, Clark J, van Kessel AG, Shipley J, van Gurp RJHLM, Gillis AJM, Oosterhuis JW. Role of gain of 12p in germ cell tumour development. APMIS 2003; 111:161-71; discussion 172-3. [PMID: 12752258 DOI: 10.1034/j.1600-0463.2003.11101201.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Within the human testis, three entities of germ cell tumours are distinguished: the teratomas and yolk sac tumors of newborn and infants, the seminomas and nonseminomas of adolescents and young adults, referred to as testicular germ cell tumours (TGCT), and the spermatocytic seminomas. Characteristic chromosomal anomalies have been reported for each group, supporting their distinct pathogenesis. TGCT are the most common cancer in young adult men. The initiating pathogenetic event of these tumours occurs during embryonal development, affecting a primordial germ cell or gonocyte. Despite this intra-uterine initiation, the tumour will only be clinically manifest after puberty, with carcinoma in situ (IS) as the precursor. All invasive TGCT, both seminomas and nonseminomas, as well as CIS cells are aneuploid. The only consistent (structural) chromosomal abnormalities in invasive TGCT are gains of the short arm of chromosome 12, mostly due to isochromosome (i(12p)) formation. This suggests that an increase in copy number of a gene(s) on 12p is associated with the development of a clinically manifest TGCT. Despite the numerous (positional) candidate gene approaches that have been undertaken thus far, identification of a causative gene(s) has been hampered by the fact that most 12p gains involve rather large genomic intervals, containing unmanageable numbers of candidate genes. Several years ago, we initiated a search for 12p candidate genes using TGCT with a restricted 12p-amplification, cytogenetically identified as 12p11.2-p12.1. This approach is mainly based on identification of candidate genes mapped within the shortest region of overlap of amplification (SROA). In this review, data will be presented, which support the model that gain of 12p-sequences is associated with suppression of apoptosis and Sertoli cell-independence of CIS cells. So far, DAD-R is one of the most likely candidate genes involved in this process, possibly via N-glycosylation. Preliminary results on high through-put DNA- and cDNA array analyses of 12p-sequences will be presented.
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Affiliation(s)
- Leendert H J Looijenga
- Pathology/Lab. for Exp. Patho-Oncology, Erasmus MC/Daniel den Hoed Cancer Center, Rotterdam, The Netherlands
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24
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Abstract
Oligosaccharyl transferase is part of the macromolecular machinery that processes nascent proteins in the endoplasmic reticulum. The enzyme is highly conserved, catalyzes the initial step in the biosynthesis of N-linked glycoproteins and acts as a 'gatekeeper' for the secretory pathway. As more proteins associated with oligosaccharyl transferase are identified, the intricacies of the enzyme and the relationship with other proteins in the lumen of the endoplasmic reticulum are starting to be unraveled.
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Affiliation(s)
- Robert E Dempski
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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25
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Nikonov AV, Snapp E, Lippincott-Schwartz J, Kreibich G. Active translocon complexes labeled with GFP-Dad1 diffuse slowly as large polysome arrays in the endoplasmic reticulum. J Cell Biol 2002; 158:497-506. [PMID: 12163472 PMCID: PMC2173836 DOI: 10.1083/jcb.200201116] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the ER, the translocon complex (TC) functions in the translocation and cotranslational modification of proteins made on membrane-bound ribosomes. The oligosaccharyltransferase (OST) complex is associated with the TC, and performs the cotranslational N-glycosylation of nascent polypeptide chains. Here we use a GFP-tagged subunit of the OST complex (GFP-Dad1) that rescues the temperature-sensitive (ts) phenotype of tsBN7 cells, where Dad1 is degraded and N-glycosylation is inhibited, to study the lateral mobility of the TC by FRAP. GFP-Dad1 that is functionally incorporated into TCs diffuses extremely slow, exhibiting an effective diffusion constant (Deff) about seven times lower than that of GFP-tagged ER membrane proteins unhindered in their lateral mobility. Termination of protein synthesis significantly increases the lateral mobility of GFP-Dad1 in the ER membranes, but to a level that is still lower than that of free GFP-Dad1. This suggests that GFP-Dad1 as part of the OST remains associated with inactive TCs. Our findings that TCs assembled into membrane-bound polysomes diffuse slowly within the ER have mechanistic implications for the segregation of the ER into smooth and rough domains.
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Affiliation(s)
- Andrei V Nikonov
- Department of Cell Biology, New York University School of Medicine, New York 10016, USA
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26
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Yoshimi M, Sekiguchi T, Hara N, Nishimoto T. Inhibition of N-linked glycosylation causes apoptosis in hamster BHK21 cells. Biochem Biophys Res Commun 2000; 276:965-9. [PMID: 11027576 DOI: 10.1006/bbrc.2000.3565] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The tsBN7 cell line is one of the temperature-sensitive mutants for cell proliferation derived from hamster BHK21 cell line. It has a mutation in the DAD1 gene and enters apoptosis at the restrictive temperature of 39 degrees C. The defect of Dad1p causes a loss of N-linked glycosylation; therefore, it was thought that an inhibition of N-linked glycosylation induced apoptosis.However, tunicamycin, a potent inhibitor of N-linked glycosylation, had not caused apoptosis in wild-type BHK21 cells. In order to clarify this discrepancy, wild-type BHK21 cells treated with tunicamycin and tsBN7 cells incubated at 39.5 degrees C were examined by the annexin V staining and TUNEL methods. Both methods showed that tunicamycin induces apoptosis in wild-type BHK21 cells, similar to the defect of Dad1p. Thus, we concluded that loss of N-linked glycosylation causes apoptosis.
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Affiliation(s)
- M Yoshimi
- Kyushu University, Department of Molecular Biology, Fukuoka, 812-8582, Japan
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27
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Kuittinen T, Eggert A, Lindholm P, Horelli-Kuitunen N, Palotie A, Maris JM, Saarma M. A novel human processed gene, DAD-R, maps to 12p12 and is expressed in several organs. FEBS Lett 2000; 473:233-6. [PMID: 10812081 DOI: 10.1016/s0014-5793(00)01358-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A cDNA of a processed gene of human DAD-1 (defender against apoptotic cell death) was cloned from the human neuroblastoma cell line SH-SY5Y. The genomic sequence of this novel processed gene, DAD-R, lacked introns and was flanked by 8 bp terminal repeats. RT-PCR showed that the transcript is expressed predominantly in testis, ovaries, pancreas, lung and skeletal muscle. DAD-R has several possible initiation codons, one of them producing an open reading frame comprising 75% of the DAD-1 gene. We determined the chromosomal localization of DAD-R as 12p11.2-12p12.1, an area linked to familial synpolydactyly and frequently amplified in a variety of cancers, including those of testis, ovaries, pancreas and lungs.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Chromosome Banding
- Chromosome Mapping
- Chromosomes, Human, Pair 12/genetics
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Female
- Gene Expression
- Humans
- In Situ Hybridization, Fluorescence
- Male
- Molecular Sequence Data
- Pseudogenes
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Repressor Proteins/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
- Tissue Distribution
- Tumor Cells, Cultured
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Affiliation(s)
- T Kuittinen
- Insitute of Biotechnology, Viikki Biocenter, P.O. Box 56 (Viikinkaari 9), FIN-00014 University of, Helsinki, Finland.
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28
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Lindholm P, Kuittinen T, Sorri O, Guo D, Merits A, Törmäkangas K, Runeberg-Roos P. Glycosylation of phytepsin and expression of dad1, dad2 and ost1 during onset of cell death in germinating barley scutella. Mech Dev 2000; 93:169-73. [PMID: 10781951 DOI: 10.1016/s0925-4773(00)00254-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Dysfunction and downregulation of dad (defending against death) has been linked to programmed cell death (PCD) in animals and plants. As DAD is an essential subunit of the oligosaccharyltransferase that is located in the ER membrane, the results have raised the possibility that downregulation of N-linked glycosylation could be involved in the regulation of PCD. Here we show that the 16 kDa subunit of phytepsin, a vacuolar proteinase, is normally processed and glycosylated at the onset of DNA fragmentation in germinating barley scutella. Two cDNA clones encoding dad (dad1, dad2), and one cDNA encoding another subunit of the same oligosaccharyltransferase complex (ost1) were isolated from barley. Northern analysis of germinating scutella show that the expression of only dad1 is declining before onset of DNA fragmentation. In contrast to this, the expression of both dad2 and ost1 increase before onset of DNA fragmentation.
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Affiliation(s)
- P Lindholm
- Institute of Biotechnology, Viikki Biocenter, Program of Plant Molecular Biology, P.O. Box 56, FIN-00014 University of Helsinki, Finland
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29
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Fu J, Pirozzi G, Sanjay A, Levy R, Chen Y, De Lemos-Chiarandini C, Sabatini D, Kreibich G. Localization of ribophorin II to the endoplasmic reticulum involves both its transmembrane and cytoplasmic domains. Eur J Cell Biol 2000; 79:219-28. [PMID: 10826490 PMCID: PMC7134489 DOI: 10.1078/s0171-9335(04)70025-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proteins that are concentrated in specific compartments of the endomembrane system in order to exert their organelle-specific function must possess specific localization signals that prevent their transport to distal regions of the exocytic pathway. Some resident proteins of the endoplasmic reticulum (ER) that are known to escape with low efficiency from this organelle to a post ER compartment are recognized by a recycling receptor and brought back to their site of residence. Other ER proteins, however, appear to be retained in the ER by mechanisms that operate in the organelle itself. The mammalian oligosaccharyltransferase (OST) is a protein complex that effects the cotranslational N-glycosylation of newly synthesized polypeptides, and is composed of at least four rough ER-specific membrane proteins: ribophorins I and II (RI and RII), OST48, and Dadl. The mechanism(s) by which the subunits of this complex are retained in the ER are not well understood. In an effort to identify the domains within RII responsible for its ER localization we have studied the fate of chimeric proteins in which one or more RII domains were replaced by the corresponding ones of the Tac antigen, the latter being a well characterized plasma membrane protein that lacks intrinsic ER retention signals and serves to provide a neutral framework for the identification of retention signals in other proteins. We found that the luminal domain of RII by itself does not contain retention information, while the cytoplasmic and transmembrane domains contain independent ER localization signals. We also show that the retention function of the transmembrane domain is strengthened by the presence of a flanking luminal region consisting of 15 amino acids.
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Affiliation(s)
- J Fu
- Department of Cell Biology, New York University Medical Center, New York 10016, USA
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Hong NA, Flannery M, Hsieh SN, Cado D, Pedersen R, Winoto A. Mice lacking Dad1, the defender against apoptotic death-1, express abnormal N-linked glycoproteins and undergo increased embryonic apoptosis. Dev Biol 2000; 220:76-84. [PMID: 10720432 DOI: 10.1006/dbio.2000.9615] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dad1 has been shown to play a role in preventing apoptotic cell death and in regulating levels of N-linked glycosylation in Saccharomyces cerevisiae and the BHK hamster cell line. To address the in vivo role of Dad1 in these processes during multicellular development, we have analyzed mice carrying a null allele for Dad1. Embryos homozygous for this mutation express abnormal N-glycosylated proteins and are developmentally delayed by embryonic day 7.5. Such mutants exhibit aberrant morphology, impaired mesodermal development, and increased levels of apoptosis in specific tissues. These defects culminate in homozygous embryos failing to turn the posterior axis and subsequent lethality by embryonic day 10.5. Thus, Dad1 is required for proper processing of N-linked glycoproteins and for certain cell survival in the mouse.
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Affiliation(s)
- N A Hong
- Division of Immunology and Cancer Research Laboratory, Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720-3200, USA
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Hong NA, Kabra NH, Hsieh SN, Cado D, Winoto A. In Vivo Overexpression of Dad1, the Defender Against Apoptotic Death-1, Enhances T Cell Proliferation But Does Not Protect Against Apoptosis. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.4.1888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Abstract
The Dad1 protein has been shown to play a role in prevention of apoptosis in certain cell types. Dad1 is also a subunit of the oligosaccharyltransferase enzyme complex that initiates N-linked glycosylation. It is encoded by a gene located adjacent to the TCR α and δ genes on mouse chromosome 14. We have investigated the role of Dad1 during T cell development and activation. We observe that endogenous Dad1 levels are modulated during T cell development to reach maximal expression in mature thymocytes. Transgenic mice that overexpress Dad1 in both the thymus and peripheral immune system have been generated. Apoptosis of thymocytes from such mice is largely unaffected, but peripheral T cells display hyperproliferation in response to stimuli. Therefore, the linkage between the TCR and Dad1 genes may have important consequences for T cell function.
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Affiliation(s)
- N. A. Hong
- Division of Immunology and Cancer Research Laboratory, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - N. H. Kabra
- Division of Immunology and Cancer Research Laboratory, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - S. N. Hsieh
- Division of Immunology and Cancer Research Laboratory, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - D. Cado
- Division of Immunology and Cancer Research Laboratory, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - A. Winoto
- Division of Immunology and Cancer Research Laboratory, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
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Nishii K, Tsuzuki T, Kumai M, Takeda N, Koga H, Aizawa S, Nishimoto T, Shibata Y. Abnormalities of developmental cell death in Dad1-deficient mice. Genes Cells 1999; 4:243-52. [PMID: 10336695 DOI: 10.1046/j.1365-2443.1999.00256.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Dad1, the defender against apoptotic cell death, comprises the oligosaccharyltransferase complex and is well conserved among eukaryotes. In hamster BHK21-derived tsBN7 cells, loss of Dad1 causes apoptosis which cannot be prevented by Bcl-2. RESULTS To determine the role of Dad1 function in vivo, we prepared by gene targeting, mice harbouring a disrupted Dad1 gene. Homozygous mutants died shortly after they were implanted with the characteristic features of apoptosis. In an in vitro blastocyst culture system, Dad1-null cells displayed abnormalities which were comparable to those obtained in vivo. However, oligosaccharyltransferase activity was apparently retained even after the Dad1-null cells were destined to die. Some live-born heterozygous mutants displayed soft-tissue syndactyly. Mild thymic hypoplasia was also indicated in heterozygotes. CONCLUSION These results suggest the involvement of the Dad1 gene in the acquisition of a common syndactyly phenotype, as well as in the control of programmed cell death during development.
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Affiliation(s)
- K Nishii
- Department of Developmental Molecular Anatomy, Faculty of Medicine, Kyushu University, 3-1-1 Maidashi, Fukuoka 812-8582, Japan.
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Knauer R, Lehle L. The oligosaccharyltransferase complex from yeast. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1426:259-73. [PMID: 9878773 DOI: 10.1016/s0304-4165(98)00128-7] [Citation(s) in RCA: 164] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
N-Glycosylation of eukaryotic secretory and membrane-bound proteins is an essential and highly conserved protein modification. The key step of this pathway is the en bloc transfer of the high mannose core oligosaccharide Glc3Man9GlcNAc2 from the lipid carrier dolichyl phosphate to selected Asn-X-Ser/Thr sequences of nascent polypeptide chains during their translocation across the endoplasmic reticulum membrane. The reaction is catalysed by the enzyme oligosaccharyltransferase (OST). Recent biochemical and molecular genetic studies in yeast have yielded novel insights into this enzyme with multiple tasks. Nine proteins have been shown to be OST components. These are assembled into a heterooligomeric membrane-bound complex and are required for optimal expression of OST activity in vivo in wild type cells. In accord with the evolutionary conservation of core N-glycosylation, there are significant homologies between the protein sequences of OST subunits from yeast and higher eukaryotes, and OST complexes from different sources show a similar organisation as well.
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Affiliation(s)
- R Knauer
- Lehrstuhl für Zellbiologie und Pflanzenphysiologie, Universität Regensburg, 93040 Regensburg, Germany
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Sanjay A, Fu J, Kreibich G. DAD1 is required for the function and the structural integrity of the oligosaccharyltransferase complex. J Biol Chem 1998; 273:26094-9. [PMID: 9748289 DOI: 10.1074/jbc.273.40.26094] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Asparagine-linked glycosylation is a highly conserved protein modification reaction that occurs in all eukaryotic organisms. The oligosaccharyltransferase (OST), which has its active site exposed on the luminal face of the endoplasmic reticulum (ER), catalyzes the transfer of preassembled high mannose oligosaccharides onto certain asparagine residues of nascent polypeptides. The mammalian OST complex was initially thought to be composed of three transmembrane proteins, ribophorin I (RI), ribophorin II (RII), and OST48. Most recently, a small integral membrane protein of 12 kDa called DAD1 has been identified as an additional member of the mammalian OST complex. A point mutation in the DAD1 gene is responsible for the temperature-sensitive phenotype of a baby hamster kidney-derived cell line (tsBN7) that undergoes apoptosis at the non-permissive temperature. Furthermore, the mutant protein DAD1 is not detectable in tsBN7 cells 6 h after shifting the cells to the non-permissive temperature. This temperature-sensitive cell line offered unique opportunities to study the effects caused by the loss of one OST subunit on the other three subunits and also on N-linked glycosylation. Western blot analysis of cell lysates showed that after 6 h at the non-permissive temperature, steady-state levels of the ribophorins were reduced by about 50%, and OST48 was barely detectable. On the other hand, steady-state levels of other components of the rough ER, such as the alpha-subunits of the TRAP (translocon-associated membrane protein) and the Sec61 complex, which are components of the translocation apparatus, are not affected by the instability of the OST subunits. Furthermore, N-glycosylation of the ribophorins was seriously affected 6 h after shifting the cells to the non-permissive temperature, and after 12 h they were synthesized only in the non-glycosylated form. As may be expected, this defect in the OST complex at the non-permissive temperature caused also the underglycosylation of a secretory glycoprotein. We concluded that degradation of DAD1 at the non-permissive temperature not only affects the stability of OST48 and the ribophorins but also results in the functional inactivation of the OST complex.
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Affiliation(s)
- A Sanjay
- Department of Cell Biology, New York University School of Medicine, New York, New York 10016, USA
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35
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Walker BK, Lei H, Krag SS. A functional link between N-linked glycosylation and apoptosis in Chinese hamster ovary cells. Biochem Biophys Res Commun 1998; 250:264-70. [PMID: 9753618 DOI: 10.1006/bbrc.1998.9304] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Seven different Chinese hamster ovary (CHO) cell mutants, isolated in different ways and having biochemical defects that were expressed at 34 degrees C, were found to be temperature sensitive for growth at 40.5 degrees C. Six of the mutants had five different lesions in N-linked glycosylation; two mutants were in the same complementation group. The temperature-sensitive phenotype in three mutants appeared by cell fusion studies to be linked to the glycosylation phenotype. In some of the glycosylation mutants [B4-2-1 (Lec15.1), Lec9, Lec1, and Lec24], but not in all of them (MI5-4 and MI8-5), incubation at 40.5 degrees C induced apoptosis, as determined by appearance of DNA fragmentation. Tunicamycin (TM) also induced apoptosis in both parental and Lec9 cells. There was a direct correlation between inhibition of glycosylation by TM treatment and induction of apoptosis. Induction of apoptosis by TM was inhibited by cycloheximide. These studies suggest that specific alterations in N-linked glycosylation in CHO cells are endogenous inducers of apoptosis.
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Affiliation(s)
- B K Walker
- Department of Biochemistry, Johns Hopkins University, School of Hygiene and Public Health, Baltimore, Maryland 20205, USA
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36
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Runeberg-Roos P, Saarma M. Phytepsin, a barley vacuolar aspartic proteinase, is highly expressed during autolysis of developing tracheary elements and sieve cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1998; 15:139-145. [PMID: 9744102 DOI: 10.1046/j.1365-313x.1998.00187.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Vacuolarisation, formation of autophagocytotic vacuoles and tonoplast disruption have been reported in plant cells undergoing developmentally regulated programmed cell death (PCD), but little is known about the vacuolar proteins involved. In HeLa cells, cathepsin D, a lysosomal aspartic proteinase has been shown to mediate PCD. Based on immunohistochemical staining of barley roots, we show here that the previously well characterised barley vacuolar aspartic proteinase (phytepsin), a plant homologue to cathepsin D, is highly expressed both during formation of tracheary elements and during partial autolysis of sieve cells. In serial transverse sections of the vascular cylinder, starting from the root tip, phytepsin is expressed in root cap cells, in the tracheary elements of early and late metaxylem, and in the sieve cells of the protophloem and metaphloem. Aleurain, a barley vacuolar cysteine proteinase, is expressed similarly in root cap cells but differently in the tracheary elements of protoxylem and early metaxylem. This is the first evidence that a vacuolar aspartic proteinase, in analogy to cathepsin D in animals, may play a role in the active autolysis of plant cells.
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Affiliation(s)
- P Runeberg-Roos
- Institute of Biotechnology, Viikki Biocenter, University of Helsinki, Finland.
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37
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Kukuruzinska MA, Lennon K. Protein N-glycosylation: molecular genetics and functional significance. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 1998; 9:415-48. [PMID: 9825220 DOI: 10.1177/10454411980090040301] [Citation(s) in RCA: 119] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Protein N-glycosylation is a metabolic process that has been highly conserved in evolution. In all eukaryotes, N-glycosylation is obligatory for viability. It functions by modifying appropriate asparagine residues of proteins with oligosaccharide structures, thus influencing their properties and bioactivities. N-glycoprotein biosynthesis involves a multitude of enzymes, glycosyltransferases, and glycosidases, encoded by distinct genes. The majority of these enzymes are transmembrane proteins that function in the endoplasmic reticulum and Golgi apparatus in an ordered and well-orchestrated manner. The complexity of N-glycosylation is augmented by the fact that different asparagine residues within the same polypeptide may be modified with different oligosaccharide structures, and various proteins are distinguished from one another by the characteristics of their carbohydrate moieties. Furthermore, biological consequences of derivatization of proteins with N-glycans range from subtle to significant. In the past, all these features of N-glycosylation have posed a formidable challenge to an elucidation of the physiological role for this modification. Recent advances in molecular genetics, combined with the availability of diverse in vivo experimental systems ranging from yeast to transgenic mice, have expedited the identification, isolation, and characterization of N-glycosylation genes. As a result, rather unexpected information regarding relationships between N-glycosylation and other cellular functions--including secretion, cytoskeletal organization, proliferation, and apoptosis--has emerged. Concurrently, increased understanding of molecular details of N-glycosylation has facilitated the alignment between N-glycosylation deficiencies and human diseases, and has highlighted the possibility of using N-glycan expression on cells as potential determinants of disease and its progression. Recent studies suggest correlations between N-glycosylation capacities of cells and drug sensitivities, as well as susceptibility to infection. Therefore, knowledge of the regulatory features of N-glycosylation may prove useful in the design of novel therapeutics. While facing the demanding task of defining properties, functions, and regulation of the numerous, as yet uncharacterized, N-glycosylation genes, glycobiologists of the 21st century offer exciting possibilities for new approaches to disease diagnosis, prevention, and cure.
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Affiliation(s)
- M A Kukuruzinska
- Department of Molecular and Cell Biology, School of Dental Medicine, Boston University Medical Center, Massachusetts 02118, USA
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Nishijima H, Nishitani H, Seki T, Nishimoto T. A dual-specificity phosphatase Cdc25B is an unstable protein and triggers p34(cdc2)/cyclin B activation in hamster BHK21 cells arrested with hydroxyurea. J Cell Biol 1997; 138:1105-16. [PMID: 9281587 PMCID: PMC2136770 DOI: 10.1083/jcb.138.5.1105] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
By incubating at 30 degrees C in the presence of an energy source, p34(cdc2)/cyclin B was activated in the extract prepared from a temperature-sensitive mutant, tsBN2, which prematurely enters mitosis at 40 degrees C, the nonpermissive temperature (Nishimoto, T. , E. Eilen, and C. Basilico. 1978. Cell. 15:475-483), and wild-type cells of the hamster BHK21 cell line arrested in S phase, without protein synthesis. Such an in vitro activation of p34(cdc2)/cyclin B, however, did not occur in the extract prepared from cells pretreated with protein synthesis inhibitor cycloheximide, although this extract still retained the ability to inhibit p34(cdc2)/cyclin B activation. When tsBN2 cells arrested in S phase were incubated at 40 degrees C in the presence of cycloheximide, Cdc25B, but not Cdc25A and C, among a family of dual-specificity phosphatases, Cdc25, was lost coincidentally with the lack of the activation of p34(cdc2)/cyclin B. Consistently, the immunodepletion of Cdc25B from the extract inhibited the activation of p34(cdc2)/cyclin B. Cdc25B was found to be unstable (half-life < 30 min). Cdc25B, but not Cdc25C, immunoprecipitated from the extract directly activated the p34(cdc2)/cyclin B of cycloheximide-treated cells as well as that of nontreated cells, although Cdc25C immunoprecipitated from the extract of mitotic cells activated the p34(cdc2)/cyclin B within the extract of cycloheximide-treated cells. Our data suggest that Cdc25B made an initial activation of p34(cdc2)/cyclin B, which initiates mitosis through the activation of Cdc25C.
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Affiliation(s)
- H Nishijima
- Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka 812-82, Japan
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