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Wu Y, Shi A, Li W, Zhang J, Lu Y, Zhang Y, Wang S. The metabolism and transformation of casein-bound lactulosyllysine in vivo: Promoting dicarbonyl stress and the formation of advanced glycation end products accompanied by systemic inflammation. Food Chem 2024; 444:138681. [PMID: 38335684 DOI: 10.1016/j.foodchem.2024.138681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/19/2024] [Accepted: 02/03/2024] [Indexed: 02/12/2024]
Abstract
Lactulosyllysine (LL) widely exists in thermally processed dairy products, while the metabolism and transformation of LL remain poorly understood. We aimed to elucidate the metabolic pathways of LL and its impact on body health by subjecting C57BL/6 mice to a short-term ll-fortified casein diet. Our findings indicated that casein-bound LL might be metabolized and transformed into 3-deoxyglucosone through fructosamine-3-kinase (FN3K) in vivo, which promoted α-dicarbonyl stress, ultimately leading to the formation of advanced glycation end products (AGEs) in various tissues/organs, accompanied by systemic inflammation. The levels of AGEs formation in tissues/organs at various stages of casein-bound LL intake exhibited dynamic changes, correlating with alterations in the expression of FN3K and α-dicarbonyl compounds metabolic detoxification enzymes. The negative effects induced by casein-bound LL cannot be fully reversed by switching to a standard diet for equal periods. Consumption of dairy products rich in LL raises concerns as a potential risk factor for healthy individuals.
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Affiliation(s)
- Yuekun Wu
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China.
| | - Aiying Shi
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China.
| | - Wanhua Li
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China.
| | - Jinhui Zhang
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China.
| | - Yingshuang Lu
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China.
| | - Yan Zhang
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China.
| | - Shuo Wang
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China.
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2
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Zheng N, Wei J, Wu D, Xu Y, Guo J. Master kinase PDK1 in tumorigenesis. Biochim Biophys Acta Rev Cancer 2023; 1878:188971. [PMID: 37640147 DOI: 10.1016/j.bbcan.2023.188971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 07/13/2023] [Accepted: 08/05/2023] [Indexed: 08/31/2023]
Abstract
3-phosphoinositide-dependent protein kinase 1 (PDK1) is considered as master kinase regulating AGC kinase family members such as AKT, SGK, PLK, S6K and RSK. Although autophosphorylation regulates PDK1 activity, accumulating evidence suggests that PDK1 is manipulated by many other mechanisms, including S6K-mediated phosphorylation, and the E3 ligase SPOP-mediated ubiquitination and degradation. Dysregulation of these upstream regulators or downstream signals involves in cancer development, as PDK1 regulating cell growth, metastasis, invasion, apoptosis and survival time. Meanwhile, overexpression of PDK1 is also exposed in a plethora of cancers, whereas inhibition of PDK1 reduces cell size and inhibits tumor growth and progression. More importantly, PDK1 also modulates the tumor microenvironments and markedly influences tumor immunotherapies. In summary, we comprehensively summarize the downstream signals, upstream regulators, mouse models, inhibitors, tumor microenvironment and clinical treatments for PDK1, and highlight PDK1 as a potential cancer therapeutic target.
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Affiliation(s)
- Nana Zheng
- National Clinical Research Center for Hematologic Diseases, Jiangsu Institute of Hematology, The First Affiliated Hospital of Soochow University, Institute of Blood and Marrow Transplantation, Collaborative Innovation Center of Hematology, Soochow University, Suzhou 215006, China
| | - Jiaqi Wei
- National Clinical Research Center for Hematologic Diseases, Jiangsu Institute of Hematology, The First Affiliated Hospital of Soochow University, Institute of Blood and Marrow Transplantation, Collaborative Innovation Center of Hematology, Soochow University, Suzhou 215006, China
| | - Depei Wu
- National Clinical Research Center for Hematologic Diseases, Jiangsu Institute of Hematology, The First Affiliated Hospital of Soochow University, Institute of Blood and Marrow Transplantation, Collaborative Innovation Center of Hematology, Soochow University, Suzhou 215006, China.
| | - Yang Xu
- National Clinical Research Center for Hematologic Diseases, Jiangsu Institute of Hematology, The First Affiliated Hospital of Soochow University, Institute of Blood and Marrow Transplantation, Collaborative Innovation Center of Hematology, Soochow University, Suzhou 215006, China.
| | - Jianping Guo
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510275, China.
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3
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Green JR, Mahalingaiah PKS, Gopalakrishnan SM, Liguori MJ, Mittelstadt SW, Blomme EAG, Van Vleet TR. Off-target pharmacological activity at various kinases: Potential functional and pathological side effects. J Pharmacol Toxicol Methods 2023; 123:107468. [PMID: 37553032 DOI: 10.1016/j.vascn.2023.107468] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 06/16/2023] [Accepted: 08/01/2023] [Indexed: 08/10/2023]
Abstract
In drug discovery, during the lead optimization and candidate characterization stages, novel small molecules are frequently evaluated in a battery of in vitro pharmacology assays to identify potential unintended, off-target interactions with various receptors, transporters, ion channels, and enzymes, including kinases. Furthermore, these screening panels may also provide utility at later stages of development to provide a mechanistic understanding of unexpected safety findings. Here, we present a compendium of the most likely functional and pathological outcomes associated with interaction(s) to a panel of 95 kinases based on an extensive curation of the scientific literature. This panel of kinases was designed by AbbVie based on safety-related data extracted from the literature, as well as from over 20 years of institutional knowledge generated from discovery efforts. For each kinase, the scientific literature was reviewed using online databases and the most often reported functional and pathological effects were summarized. This work should serve as a practical guide for small molecule drug discovery scientists and clinical investigators to predict and/or interpret adverse effects related to pharmacological interactions with these kinases.
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Affiliation(s)
- Jonathon R Green
- Departments of Preclinical Safety, AbbVie, 1 North Waukegan Road, North Chicago, IL 60064, United States.
| | | | - Sujatha M Gopalakrishnan
- Drug Discovery Science and Technology, AbbVie, 1 North Waukegan Road, North Chicago, IL 60064, United States
| | - Michael J Liguori
- Departments of Preclinical Safety, AbbVie, 1 North Waukegan Road, North Chicago, IL 60064, United States
| | - Scott W Mittelstadt
- Departments of Preclinical Safety, AbbVie, 1 North Waukegan Road, North Chicago, IL 60064, United States
| | - Eric A G Blomme
- Departments of Preclinical Safety, AbbVie, 1 North Waukegan Road, North Chicago, IL 60064, United States
| | - Terry R Van Vleet
- Departments of Preclinical Safety, AbbVie, 1 North Waukegan Road, North Chicago, IL 60064, United States
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4
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Chu F, Wan H, Xiao W, Dong H, Lü M. Ca 2+-Permeable Channels/Ca 2+ Signaling in the Regulation of Ileal Na +/Gln Co-Transport in Mice. Front Pharmacol 2022; 13:816133. [PMID: 35281933 PMCID: PMC8905502 DOI: 10.3389/fphar.2022.816133] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/13/2022] [Indexed: 11/13/2022] Open
Abstract
Oral glutamine (Gln) has been widely used in gastrointestinal (GI) clinical practice, but it is unclear if Ca2+ regulates intestinal Gln transport, although both of them are essential nutrients for mammals. Chambers were used to determine Gln (25 mM)-induced Isc through Na+/Gln co-transporters in the small intestine in the absence or the presence of selective activators or blockers of ion channels and transporters. Luminal but not serosal application of Gln induced marked intestinal Isc, especially in the distal ileum. Lowering luminal Na+ almost abolished the Gln-induced ileal Isc, in which the calcium-sensitive receptor (CaSR) activation were not involved. Ca2+ removal from both luminal and serosal sides of the ileum significantly reduced Gln- Isc. Blocking either luminal Ca2+ entry via the voltage-gated calcium channels (VGCC) or endoplasmic reticulum (ER) release via inositol 1,4,5-triphosphate receptor (IP3R) and ryanodine receptor (RyR) attenuated the Gln-induced ileal Isc, Likewise, blocking serosal Ca2+ entry via the store-operated Ca2+ entry (SOCE), TRPV1/2 channels, and Na+/Ca2+ exchangers (NCX) attenuated the Gln-induced ileal Isc. In contrast, activating TRPV1/2 channels enhanced the Gln-induced ileal Isc. We concluded that Ca2+ signaling is critical for intestinal Gln transport, and multiple plasma membrane Ca2+-permeable channels and transporters play roles in this process. The Ca2+ regulation of ileal Na+/Gln transport expands our understanding of intestinal nutrient uptake and may be significant in GI health and disease.
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Affiliation(s)
- Fenglan Chu
- Department of Gastroenterology, Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Hanxing Wan
- Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Weidong Xiao
- Department of General Surgery, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Hui Dong
- Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Muhan Lü
- Department of Gastroenterology, Affiliated Hospital of Southwest Medical University, Luzhou, China
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Gaowa N, Li W, Gelsinger S, Murphy B, Li S. Analysis of Host Jejunum Transcriptome and Associated Microbial Community Structure Variation in Young Calves with Feed-Induced Acidosis. Metabolites 2021; 11:414. [PMID: 34201826 PMCID: PMC8303401 DOI: 10.3390/metabo11070414] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/15/2021] [Accepted: 06/15/2021] [Indexed: 12/05/2022] Open
Abstract
Diet-induced acidosis imposes a health risk to young calves. In this study, we aimed to investigate the host jejunum transcriptome changes, along with its microbial community variations, using our established model of feed-induced ruminal acidosis in young calves. Eight bull calves were randomly assigned to two diet treatments beginning at birth (a starch-rich diet, Aci; a control diet, Con). Whole-transcriptome RNA sequencing was performed on the jejunum tissues collected at 17 weeks of age. Ribosomal RNA reads were used for studying microbial community structure variations in the jejunum. A total of 853 differentially expressed genes were identified (402 upregulated and 451 downregulated) between the two groups. The cell cycle and the digestion and absorption of protein in jejunal tissue were affected by acidosis. Compared to the control, genera of Campylobacter, Burkholderia, Acidaminococcus, Corynebacterium, and Olsenella significantly increased in abundance in the Aci group, while Lachnoclostridium and Ruminococcus were significantly lower in the Aci group. Expression changes in the AXL gene were associated with the abundance variations of a high number of genera in jejunum. Our study provided a snapshot of the transcriptome changes in the jejunum and its associated meta-transcriptome changes in microbial communities in young calves with feed-induced acidosis.
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Affiliation(s)
- Naren Gaowa
- College of Animal Science and Technology, China Agricultural University, No.2 Yuanmingyuan West Road, Haidian, Beijing 100193, China;
| | - Wenli Li
- Cell Wall Biology and Utilization Research Unit, US Dairy Forage Research Center, Agricultural Research Service, US Department of Agriculture, 1925 Linden Drive, Madison, WI 53706, USA;
| | - Sonia Gelsinger
- Department of Dairy Science, University of Wisconsin-Madison, Madison, WI 53706, USA;
| | - Brianna Murphy
- Cell Wall Biology and Utilization Research Unit, US Dairy Forage Research Center, Agricultural Research Service, US Department of Agriculture, 1925 Linden Drive, Madison, WI 53706, USA;
| | - Shengli Li
- College of Animal Science and Technology, China Agricultural University, No.2 Yuanmingyuan West Road, Haidian, Beijing 100193, China;
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Lichawska-Cieslar A, Pietrzycka R, Ligeza J, Kulecka M, Paziewska A, Kalita A, Dolicka DD, Wilamowski M, Miekus K, Ostrowski J, Mikula M, Jura J. RNA sequencing reveals widespread transcriptome changes in a renal carcinoma cell line. Oncotarget 2018; 9:8597-8613. [PMID: 29492220 PMCID: PMC5823589 DOI: 10.18632/oncotarget.24269] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 12/30/2017] [Indexed: 12/12/2022] Open
Abstract
We used RNA sequencing (RNA-Seq) technology to investigate changes in the transcriptome profile in the Caki-1 clear cell renal cell carcinoma (ccRCC) cells, which overexpress monocyte chemoattractant protein-induced protein 1 (MCPIP1). RNA-Seq data showed changes in 11.6% and 41.8% of the global transcriptome of Caki-1 cells overexpressing wild-type MCPIP1 or its D141N mutant, respectively. Gene ontology and KEGG pathway functional analyses showed that these transcripts encoded proteins involved in cell cycle progression, protein folding in the endoplasmic reticulum, hypoxia response and cell signalling. We identified 219 downregulated transcripts in MCPIP1-expressing cells that were either unchanged or upregulated in D141N-expressing cells. We validated downregulation of 15 transcripts belonging to different functional pathways by qRT-PCR. The growth and viability of MCPIP1-expressing cells was reduced because of elevated p21Cip1 levels. MCPIP1-expressing cells also showed reduced levels of DDB1 transcript that encodes component of the E3 ubiquitin ligase that degrades p21Cip1. These results demonstrate that MCPIP1 influences the growth and viability of ccRCC cells by increasing or decreasing the transcript levels for proteins involved in cell cycle progression, protein folding, hypoxia response, and cell signaling.
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Affiliation(s)
- Agata Lichawska-Cieslar
- Department of General Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Roza Pietrzycka
- Department of General Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Janusz Ligeza
- Department of General Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Maria Kulecka
- Departments of Gastroenterology, Hepatology and Clinical Oncology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - Agnieszka Paziewska
- Departments of Gastroenterology, Hepatology and Clinical Oncology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - Agata Kalita
- Department of General Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Dobrochna D. Dolicka
- Department of General Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Mateusz Wilamowski
- Department of General Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Katarzyna Miekus
- Department of General Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Jerzy Ostrowski
- Departments of Gastroenterology, Hepatology and Clinical Oncology, Centre of Postgraduate Medical Education, Warsaw, Poland
- Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Warsaw, Poland
| | - Michal Mikula
- Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Warsaw, Poland
| | - Jolanta Jura
- Department of General Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
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Molecular characterization of the Haemonchus contortus phosphoinositide-dependent protein kinase-1 gene (Hc-pdk-1). Parasit Vectors 2016; 9:65. [PMID: 26842781 PMCID: PMC4741024 DOI: 10.1186/s13071-016-1351-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 01/28/2016] [Indexed: 12/22/2022] Open
Abstract
Background Phosphoinositide-dependent protein kinase-1 (PDK-1), which functions downstream of phosphoinositide 3-kinase (AGE-1) and activates protein kinases of the AGC family, plays critical roles in regulating biology processes, such as metabolism, growth, development and survival. In the free-living nematode Caenorhabditis elegans, PDK-1 is a key component of the insulin-like signalling pathway, regulating the entry into and exit from dauer (arrested development). Although it is proposed that similar molecular mechanisms control the transition from the free-living to the parasitic stages of nematodes, nothing is known about PDK-1 in Haemonchus contortus, a socioeconomically important gastric nematode of ruminants. Methods Here, we isolated and characterized the pdk-1 gene (Hc-pdk-1) and its inferred product (Hc-PDK-1) from H. contortus. Using in vitro and in vivo methods, we then studied the transcriptional profiles of Hc-pdk-1 and anatomical gene expression patterns of Hc-PDK-1 in different developmental stages of C. elegans. Results In silico analysis of Hc-PDK-1 displayed conserved functional domains, such as protein kinase and pleckstrin homology (PH) domains and two predicted phosphorylation sites (Thr226/Tyr229), which are crucial for the phosphorylation of downstream signalling. The Hc-pdk-1 gene is transcribed in all of the main developmental stages of H. contortus, with its highest transcription in the infective third-stage larvae (iL3) compared with other stages. Transgene constructs, in which respective promoters were fused to the coding sequence for green fluorescent protein (GFP), were used to transform C. elegans, and to localize and compare the expression of Hc-pdk-1 and Ce-pdk-1. The expression of GFP under the control of the Hc-pdk-1 promoter was localized to the intestine, and head and tail neurons, contrasting somewhat the profile for the C. elegans ortholog, which is expressed in pharynx, intestine and head and tail neurons. Conclusions This is the first characterization of pdk-1/PDK-1 from a trichostrongyloid nematode. Taken together, the findings from this study provide a first glimpse of the involvement of Hc-pdk-1 in the insulin-like signalling pathway in H. contortus. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1351-6) contains supplementary material, which is available to authorized users.
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Locke MEO, Milojevic M, Eitutis ST, Patel N, Wishart AE, Daley M, Hill KA. Genomic copy number variation in Mus musculus. BMC Genomics 2015; 16:497. [PMID: 26141061 PMCID: PMC4490682 DOI: 10.1186/s12864-015-1713-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 06/22/2015] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Copy number variation is an important dimension of genetic diversity and has implications in development and disease. As an important model organism, the mouse is a prime candidate for copy number variant (CNV) characterization, but this has yet to be completed for a large sample size. Here we report CNV analysis of publicly available, high-density microarray data files for 351 mouse tail samples, including 290 mice that had not been characterized for CNVs previously. RESULTS We found 9634 putative autosomal CNVs across the samples affecting 6.87% of the mouse reference genome. We find significant differences in the degree of CNV uniqueness (single sample occurrence) and the nature of CNV-gene overlap between wild-caught mice and classical laboratory strains. CNV-gene overlap was associated with lipid metabolism, pheromone response and olfaction compared to immunity, carbohydrate metabolism and amino-acid metabolism for wild-caught mice and classical laboratory strains, respectively. Using two subspecies of wild-caught Mus musculus, we identified putative CNVs unique to those subspecies and show this diversity is better captured by wild-derived laboratory strains than by the classical laboratory strains. A total of 9 genic copy number variable regions (CNVRs) were selected for experimental confirmation by droplet digital PCR (ddPCR). CONCLUSION The analysis we present is a comprehensive, genome-wide analysis of CNVs in Mus musculus, which increases the number of known variants in the species and will accelerate the identification of novel variants in future studies.
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Affiliation(s)
- M Elizabeth O Locke
- Department of Computer Science, The University of Western Ontario, London, ON, N6A 5B7, Canada.
| | - Maja Milojevic
- Department of Biology, The University of Western Ontario, Biological and Geological Sciences Building 1151 Richmond St. N, London, ON, N6A 5B7, Canada.
| | - Susan T Eitutis
- Department of Biology, The University of Western Ontario, Biological and Geological Sciences Building 1151 Richmond St. N, London, ON, N6A 5B7, Canada.
| | - Nisha Patel
- Department of Biology, The University of Western Ontario, Biological and Geological Sciences Building 1151 Richmond St. N, London, ON, N6A 5B7, Canada.
| | - Andrea E Wishart
- Department of Biology, The University of Western Ontario, Biological and Geological Sciences Building 1151 Richmond St. N, London, ON, N6A 5B7, Canada.
| | - Mark Daley
- Department of Computer Science, The University of Western Ontario, London, ON, N6A 5B7, Canada.
- Department of Biology, The University of Western Ontario, Biological and Geological Sciences Building 1151 Richmond St. N, London, ON, N6A 5B7, Canada.
| | - Kathleen A Hill
- Department of Computer Science, The University of Western Ontario, London, ON, N6A 5B7, Canada.
- Department of Biology, The University of Western Ontario, Biological and Geological Sciences Building 1151 Richmond St. N, London, ON, N6A 5B7, Canada.
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9
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Minton DR, Fu L, Chen Q, Robinson BD, Gross SS, Nanus DM, Gudas LJ. Analyses of the transcriptome and metabolome demonstrate that HIF1α mediates altered tumor metabolism in clear cell renal cell carcinoma. PLoS One 2015; 10:e0120649. [PMID: 25830305 PMCID: PMC4382166 DOI: 10.1371/journal.pone.0120649] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/25/2015] [Indexed: 01/01/2023] Open
Abstract
Hypoxia inducible factor 1 alpha (HIF1α) is a transcription factor that is frequently stabilized and active in human clear cell renal cell carcinoma (ccRCC). We have found that constitutively active HIF1α is sufficient to cause neoplastic transformation in a murine model of ccRCC termed the TRACK model. RNA sequencing (RNAseq) and untargeted metabolomics analyses of samples from TRACK kidneys demonstrate that HIF1α activates the transcription of genes that cause increased glucose uptake, glycolysis, and lactate production, as well as a decrease in the flux of pyruvate entering the tricarboxylic acid (TCA) cycle and a decrease in oxidative phosphorylation; these changes are identical to those observed in human ccRCC samples. These studies show that a constitutively active HIF1α promotes tumorigenesis in TRACK mice by mediating a metabolic switch to aerobic glycolysis, i.e., the Warburg effect, and suggest that TRACK mice are a valid model to test novel therapies targeting metabolic changes to inhibit human ccRCC.
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Affiliation(s)
- Denise R. Minton
- Department of Pharmacology, Weill Cornell Graduate School of Medical Sciences, New York, New York, United States of America
| | - Leiping Fu
- Department of Pharmacology, Weill Cornell Graduate School of Medical Sciences, New York, New York, United States of America
| | - Qiuying Chen
- Department of Pharmacology, Weill Cornell Graduate School of Medical Sciences, New York, New York, United States of America
| | - Brian D. Robinson
- Department of Pathology, Weill Cornell Medical College, New York, New York, United States of America
| | - Steven S. Gross
- Department of Pharmacology, Weill Cornell Graduate School of Medical Sciences, New York, New York, United States of America
| | - David M. Nanus
- Division of Hematology and Medical Oncology, Department of Medicine, Weill Cornell Medical College, New York, New York, United States of America
- Weill Cornell Meyer Cancer Center, Weill Cornell Medical College, New York, New York, United States of America
| | - Lorraine J. Gudas
- Department of Pharmacology, Weill Cornell Graduate School of Medical Sciences, New York, New York, United States of America
- Division of Hematology and Medical Oncology, Department of Medicine, Weill Cornell Medical College, New York, New York, United States of America
- Weill Cornell Meyer Cancer Center, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail:
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10
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Giacopo AD, Rubio-Aliaga I, Cantone A, Artunc F, Rexhepaj R, Frey-Wagner I, Font-Llitjós M, Gehring N, Stange G, Jaenecke I, Mohebbi N, Closs EI, Palacín M, Nunes V, Daniel H, Lang F, Capasso G, Wagner CA. Differential cystine and dibasic amino acid handling after loss of function of the amino acid transporter b0,+AT (Slc7a9) in mice. Am J Physiol Renal Physiol 2013; 305:F1645-55. [DOI: 10.1152/ajprenal.00221.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cystinuria is an autosomal recessive disease caused by mutations in SLC3A1 ( rBAT) and SLC7A9 ( b 0,+ AT). Gene targeting of the catalytic subunit ( Slc7a9) in mice leads to excessive excretion of cystine, lysine, arginine, and ornithine. Here, we studied this non-type I cystinuria mouse model using gene expression analysis, Western blotting, clearance, and brush-border membrane vesicle (BBMV) uptake experiments to further characterize the renal and intestinal consequences of losing Slc7a9 function. The electrogenic and BBMV flux studies in the intestine suggested that arginine and ornithine are transported via other routes apart from system b0,+. No remarkable gene expression changes were observed in other amino acid transporters and the peptide transporters in the intestine and kidney. Furthermore, the glomerular filtration rate (GFR) was reduced by 30% in knockout animals compared with wild-type animals. The fractional excretion of arginine was increased as expected (∼100%), but fractional excretions of lysine (∼35%), ornithine (∼16%), and cystine (∼11%) were less affected. Loss of function of b0,+AT reduced transport of cystine and arginine in renal BBMVs and completely abolished the exchanger activity of dibasic amino acids with neutral amino acids. In conclusion, loss of Slc7a9 function decreases the GFR and increases the excretion of several amino acids to a lesser extent than expected with no clear regulation at the mRNA and protein level of alternative transporters and no increased renal epithelial uptake. These observations indicate that transporters located in distal segments of the kidney and/or metabolic pathways may partially compensate for Slc7a9 loss of function.
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Affiliation(s)
- Andrea Di Giacopo
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Isabel Rubio-Aliaga
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Alessandra Cantone
- Department of Internal Medicine, Chair of Nephrology, Second University of Naples, Naples, Italy
| | - Ferruh Artunc
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Rexhep Rexhepaj
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | | | - Mariona Font-Llitjós
- Medical and Molecular Genetics Center, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain
- U730 CIBERER, Barcelona, Spain
| | - Nicole Gehring
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Gerti Stange
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Isabel Jaenecke
- Department of Pharmacology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Nilufar Mohebbi
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Ellen I. Closs
- Department of Pharmacology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Manuel Palacín
- IRB Barcelona, Department of Biochemistry and Molecular Biology, University of Barcelona and U731 CIBERER, Barcelona, Spain
| | - Virginia Nunes
- Medical and Molecular Genetics Center, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain
- Department of Physiological Sciences II, University of Barcelona, Spain; and
- U730 CIBERER, Barcelona, Spain
| | - Hannelore Daniel
- Molecular Nutrition Unit, Technical University of Munich, Freising, Germany
| | - Florian Lang
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Giovambattista Capasso
- Department of Internal Medicine, Chair of Nephrology, Second University of Naples, Naples, Italy
| | - Carsten A. Wagner
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
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Neuroprotective properties of the excitatory amino acid carrier 1 (EAAC1). Amino Acids 2013; 45:133-42. [PMID: 23462929 DOI: 10.1007/s00726-013-1481-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 02/23/2013] [Indexed: 01/09/2023]
Abstract
Extracellular glutamate should be maintained at low levels to conserve optimal neurotransmission and prevent glutamate neurotoxicity in the brain. Excitatory amino acid transporters (EAATs) play a pivotal role in removing extracellular glutamate in the central nervous system (CNS). Excitatory amino acid carrier 1 (EAAC1) is a high-affinity Na⁺-dependent neuronal EAAT that is ubiquitously expressed in the brain. However, most glutamate released in the synapses is cleared by glial EAATs, but not by EAAC1 in vivo. In the CNS, EAAC1 is widely distributed in somata and dendrites but not in synaptic terminals. The contribution of EAAC1 to the control of extracellular glutamate levels seems to be negligible in the brain. However, EAAC1 can transport not only extracellular glutamate but also cysteine into the neurons. Cysteine is an important substrate for glutathione (GSH) synthesis in the brain. GSH has a variety of neuroprotective functions, while its depletion induces neurodegeneration. Therefore, EAAC1 might exert a critical role for neuroprotection in neuronal GSH metabolism rather than glutamatergic neurotransmission, while EAAC1 dysfunction would cause neurodegeneration. Despite the potential importance of EAAC1 in the brain, previous studies have mainly focused on the glutamate neurotoxicity induced by glial EAAT dysfunction. In recent years, however, several studies have revealed regulatory mechanisms of EAAC1 functions in the brain. This review will summarize the latest information on the EAAC1-regulated neuroprotective functions in the CNS.
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Wada M, Tamura A, Takahashi N, Tsukita S. Loss of claudins 2 and 15 from mice causes defects in paracellular Na+ flow and nutrient transport in gut and leads to death from malnutrition. Gastroenterology 2013; 144:369-380. [PMID: 23089202 DOI: 10.1053/j.gastro.2012.10.035] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Revised: 10/12/2012] [Accepted: 10/16/2012] [Indexed: 01/10/2023]
Abstract
BACKGROUND & AIMS The intestinal symport system moves nutrients across membranes via transporters, and is required for absorption of major nutrients such as glucose, amino acids, and bile acids (which are required for fat absorption). Most of these transporters are regulated by Na(+), but the standard diet does not provide sufficient levels of this ion to the intestinal lumen to support this system. Claudins form paracellular barriers between epithelial cells, and claudin-2 and -15 regulate paracellular ion flow in the intestine. We investigated how cell adherence, tight junction barriers, and claudins regulate the supply of Na(+) to the intestinal lumen in mice. METHODS We created Cldn2(-/-)Cldn15(-/-) (double-knockout) mice and analyzed intestinal tissues by reverse-transcription polymerase chain reaction, immunoblot, immunofluorescence, electron microscopy, and H&E analyses. We also measured paracellular Na(+) flow, luminal Na(+) concentration, and absorption of glucose, amino acids, and fats, which were administered orally to the mice. RESULTS Paracellular flow of Na(+) from the intestinal submucosa to the lumen, and therefore the concentration of Na(+) in the lumen, was greatly reduced in intestines of Cldn2(-/-)Cldn15(-/-) mice. Absorption of glucose, amino acids, and fats also decreased in the mice, which died by postnatal day 25 from malnutrition. CONCLUSIONS The paracellular flow of Na(+) from the intestinal submucosa is regulated by tight junctions that contain claudin-2 and -15. This system is required for the absorption of glucose, amino acids, and fats; disruption of this system in mice leads to infant death as a result of malabsorption.
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Affiliation(s)
- Masami Wada
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Atsushi Tamura
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Nobuyuki Takahashi
- Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Sachiko Tsukita
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Osaka, Japan.
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Pruszynski M, Koumarianou E, Vaidyanathan G, Revets H, Devoogdt N, Lahoutte T, Zalutsky MR. Targeting breast carcinoma with radioiodinated anti-HER2 Nanobody. Nucl Med Biol 2013; 40:52-9. [PMID: 23159171 PMCID: PMC3551612 DOI: 10.1016/j.nucmedbio.2012.08.008] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 07/25/2012] [Accepted: 08/07/2012] [Indexed: 11/25/2022]
Abstract
INTRODUCTION With a molecular weight an order of magnitude lower than antibodies but possessing comparable affinities, Nanobodies (Nbs) are attractive as targeting agents for cancer diagnosis and therapy. An anti-HER2 Nb could be utilized to determine HER2 status in breast cancer patients prior to trastuzumab treatment. This provided motivation for the generation of HER2-specific 5F7GGC Nb, its radioiodination and evaluation for targeting HER2 expressing tumors. METHODS 5F7GGC Nb was radioiodinated with ¹²⁵I using Iodogen and with ¹³¹I using the residualizing agent N(ɛ)-(3-[¹³¹I]iodobenzoyl)-Lys⁵-N(α)-maleimido-Gly¹-GEEEK ([¹³¹I]IB-Mal-D-GEEEK) used previously successfully with intact antibodies. Paired-label internalization assays using BT474M1 cells and tissue distribution experiments in athymic mice bearing BT474M1 xenografts were performed to compare the two labeled Nb preparations. RESULTS The radiochemical yields for Iodogen and [¹³¹I]IB-Mal-D-GEEEK labeling were 83.6±5.0% (n=10) and 59.6±9.4% (n=15), respectively. The immunoreactivity of labeled proteins was preserved as confirmed by in vitro and in vivo binding to tumor cells. Biodistribution studies showed that Nb radiolabeled using [¹³¹I]IB-Mal-D-GEEEK, compared with the directly labeled Nb, had a higher tumor uptake (4.65±0.61% ID/g vs. 2.92±0.24% ID/g at 8h), faster blood clearance, lower accumulation in non-target organs except kidneys, and as a result, higher concomitant tumor-to-blood and tumor-to-tissue ratios. CONCLUSIONS Taken together, these results demonstrate that 5F7GGC anti-HER2 Nb labeled with residualizing [¹³¹I]IB-Mal-D-GEEEK had better tumor targeting properties compared to the directly labeled Nb suggesting the potential utility of this Nb conjugate for SPECT (¹²⁹I) and PET imaging (¹²⁴I) of patients with HER2-expressing tumors.
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Affiliation(s)
- Marek Pruszynski
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | | | | | | | - Nick Devoogdt
- In Vivo Cellular and Molecular Imaging, Vrije Universiteit Brussel, Brussels, Belgium
| | - Tony Lahoutte
- In Vivo Cellular and Molecular Imaging, Vrije Universiteit Brussel, Brussels, Belgium
| | - Michael R. Zalutsky
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA
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Aoyama K, Watabe M, Nakaki T. Modulation of neuronal glutathione synthesis by EAAC1 and its interacting protein GTRAP3-18. Amino Acids 2011; 42:163-9. [PMID: 21373771 DOI: 10.1007/s00726-011-0861-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 02/17/2011] [Indexed: 01/17/2023]
Abstract
Glutathione (GSH) plays essential roles in different processes such as antioxidant defenses, cell signaling, cell proliferation, and apoptosis in the central nervous system. GSH is a tripeptide composed of glutamate, cysteine, and glycine. The concentration of cysteine in neurons is much lower than that of glutamate or glycine, so that cysteine is the rate-limiting substrate for neuronal GSH synthesis. Most neuronal cysteine uptake is mediated through the neuronal sodium-dependent glutamate transporter, known as excitatory amino acid carrier 1 (EAAC1). Glutamate transporters are vulnerable to oxidative stress and EAAC1 dysfunction impairs neuronal GSH synthesis by reducing cysteine uptake. This may start a vicious circle leading to neurodegeneration. Intracellular signaling molecules functionally regulate EAAC1. Glutamate transporter-associated protein 3-18 (GTRAP3-18) activation down-regulates EAAC1 function. Here, we focused on the interaction between EAAC1 and GTRAP3-18 at the plasma membrane to investigate their effects on neuronal GSH synthesis. Increased level of GTRAP3-18 protein induced a decrease in GSH level and, thereby, increased the vulnerability to oxidative stress, while decreased level of GTRAP3-18 protein induced an increase in GSH level in vitro. We also confirmed these results in vivo. Our studies demonstrate that GTRAP3-18 regulates neuronal GSH level by controlling the EAAC1-mediated uptake of cysteine.
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Affiliation(s)
- Koji Aoyama
- Department of Pharmacology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi, Tokyo, 173-8605, Japan
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Bayascas JR. PDK1: the major transducer of PI 3-kinase actions. Curr Top Microbiol Immunol 2011; 346:9-29. [PMID: 20563709 DOI: 10.1007/82_2010_43] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Most of the cellular responses to phosphatidylinositol 3-kinase activation and phosphatidylinositol 3,4,5-trisphosphate production are mediated by the activation of a group of AGC kinases comprising PKB, S6K, RSK, SGK and PKC isoforms, which play essential roles in regulating physiological processes related to cell growth, proliferation, survival and metabolism. All these growth-factor-stimulated AGC kinases possess a common upstream activator, namely PDK1, a master kinase, which, being constitutively active, is still able to phosphorylate and activate its AGC substrates in response to rises in the levels of the PtdIns(3,4,5)P(3) second messenger. In this chapter, the biochemical, structural and genetic data on the mechanism of action and physiological roles of PDK1 are reviewed, and its potential as a pharmaceutical target for the design of drugs therapeutically beneficial to treat human disease such us diabetes and cancer is discussed.
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Affiliation(s)
- José Ramón Bayascas
- Institut de Neurociències & Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Barcelona, Spain.
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16
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Vaidyanathan G, Jestin E, Olafsen T, Wu AM, Zalutsky MR. Evaluation of an anti-p185(HER2) (scFv-C(H)2-C(H)3)2 fragment following radioiodination using two different residualizing labels: SGMIB and IB-Mal-D-GEEEK. Nucl Med Biol 2009; 36:671-80. [PMID: 19647173 DOI: 10.1016/j.nucmedbio.2009.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 03/31/2009] [Accepted: 04/02/2009] [Indexed: 11/15/2022]
Abstract
INTRODUCTION A 105-kDa double mutant single-chain Fv-Fc fragment (scFv-Fc DM) derived from the anti-p185(HER2) hu4D5v8 antibody (trastuzumab; Herceptin) has been described recently. The goal of this study was to investigate whether improved tumor targeting could be achieved with this fragment through the use of residualizing radioiodination methods. METHODS The scFv-Fc DM fragment was radioiodinated using N-succinimidyl 4-guanidinomethyl 3-[(131)I]iodobenzoate ([(131)I]SGMIB) and N(epsilon)-(3-[(131)I]iodobenzoyl)-Lys(5)-N(alpha)- maleimido-Gly(1)-GEEEK ([(131)I]IB-Mal-D-GEEEK), two residualizing radioiodination agents that have been used successfully with intact antibodies. Paired-label internalization assays of the labeled fragments were performed in vitro using MCF7 human breast cancer cells transfected to express HER2 (MCF7-HER2); comparisons were made to scFv-Fc DM directly radioiodinated using Iodogen. The tissue distribution of the scFv-Fc DM labeled with [(125)I]IB-Mal-d-GEEEK and [(131)I]SGMIB was compared in athymic mice bearing MCF7-HER2 xenografts. RESULTS The scFv-Fc DM fragment was labeled with [(131)I]SGMIB and [(131)I]IB-Mal-d-GEEEK in conjugation yields of 53% and 25%, respectively, with preservation of immunoreactivity for HER2. Internalization assays indicated that labeling via SGMIB resulted in a 1.6- to 3.5-fold higher (P<.05) retention of radioactivity, compared to that from the directly labeled fragment, in HER2-expressing cells during a 24-h observation period. Likewise, the amount of radioactivity retained in cells from the IB-Mal-d-GEEEK-labeled fragment was 1.4- to 3.3-fold higher (P<.05). Tumor uptake of radioiodine activity in athymic mice bearing MCF7-HER2 xenografts in vivo was significantly higher for the [(125)I]IB-Mal-d-GEEEK-labeled scFv-Fc DM fragment compared with that of the [(131)I]SGMIB-labeled fragment, particularly at later time points. The uptake of (125)I was threefold (3.6+/-1.1 %ID/g vs. 1.2+/-0.4 %ID/g) and fourfold (3.1+/-1.7 %ID/g vs. 0.8+/-0.4 %ID/g) higher than that for (131)I at 24 and 48 h, respectively. However, the [(125)I]IB-Mal-d-GEEEK-labeled scFv-Fc DM fragment also exhibited considerably higher levels of radioiodine activity in liver, spleen and kidney. CONCLUSIONS The overall results further demonstrate the potential utility of these two prosthetic groups for the radiohalogenation of internalizing monoclonal antibodies and their fragments. Specifically, the trastuzumab-derived double mutant fragment in combination with these residualizing agents warrants further evaluation for imaging and possibly treatment of HER2 expressing malignancies.
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Klaus F, Gehring EM, Zürn A, Laufer J, Lindner R, Strutz-Seebohm N, Tavaré JM, Rothstein JD, Boehmer C, Palmada M, Gruner I, Lang UE, Seebohm G, Lang F. Regulation of the Na+-coupled glutamate transporter EAAT3 by PIKfyve. Neurochem Int 2009; 54:372-7. [DOI: 10.1016/j.neuint.2009.01.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Abstract
The brain is among the major organs generating large amounts of reactive oxygen species and is especially susceptible to oxidative stress. Glutathione (GSH) plays critical roles as an antioxidant, enzyme cofactor, cysteine storage form, the major redox buffer, and a neuromodulator in the central nervous system. GSH deficiency has been implicated in neurodegenerative diseases. GSH is a tripeptide comprised of glutamate, cysteine, and glycine. Cysteine is the rate-limiting substrate for GSH synthesis within neurons. Most neuronal cysteine uptake is mediated by sodium-dependent excitatory amino acid transporter (EAAT) systems, known as excitatory amino acid carrier 1 (EAAC1). Previous studies demonstrated EAAT is vulnerable to oxidative stress, leading to impaired function. A recent study found EAAC1-deficient mice to have decreased brain GSH levels and increased susceptibility to oxidative stress. The function of EAAC1 is also regulated by glutamate transporter associated protein 3-18. This review focuses on the mechanisms underlying GSH synthesis, especially those related to neuronal cysteine transport via EAAC1, as well as on the importance of GSH functions against oxidative stress.
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Affiliation(s)
- Koji Aoyama
- Department of Pharmacology, Teikyo University School of Medicine, Itabashi, Tokyo, Japan
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Abstract
The TOR (target of rapamycin), an atypical protein kinase, is evolutionarily conserved from yeast to man. Pharmacological studies using rapamycin to inhibit TOR and yeast genetic studies have provided key insights on the function of TOR in growth regulation. One of the first bona fide cellular targets of TOR was the mammalian protein kinase p70 S6K (p70 S6 kinase), a member of a family of kinases called AGC (protein kinase A/protein kinase G/protein kinase C-family) kinases, which include PKA (cAMP-dependent protein kinase A), PKG (cGMP-dependent kinase) and PKC (protein kinase C). AGC kinases are also highly conserved and play a myriad of roles in cellular growth, proliferation and survival. The AGC kinases are regulated by a common scheme that involves phosphorylation of the kinase activation loop by PDK1 (phosphoinositide-dependent kinase 1), and phosphorylation at one or more sites at the C-terminal tail. The identification of two distinct TOR protein complexes, TORC1 (TOR complex 1) and TORC2, with different sensitivities to rapamycin, revealed that TOR, as part of either complex, can mediate phosphorylation at the C-terminal tail for optimal activation of a number of AGC kinases. Together, these studies elucidated that a fundamental function of TOR conserved throughout evolution may be to balance growth versus survival signals by regulating AGC kinases in response to nutrients and environmental conditions. This present review highlights this emerging function of TOR that is conserved from budding and fission yeast to mammals.
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Mutation of the PDK1 PH domain inhibits protein kinase B/Akt, leading to small size and insulin resistance. Mol Cell Biol 2008; 28:3258-72. [PMID: 18347057 DOI: 10.1128/mcb.02032-07] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PDK1 activates a group of kinases, including protein kinase B (PKB)/Akt, p70 ribosomal S6 kinase (S6K), and serum and glucocorticoid-induced protein kinase (SGK), that mediate many of the effects of insulin as well as other agonists. PDK1 interacts with phosphoinositides through a pleckstrin homology (PH) domain. To study the role of this interaction, we generated knock-in mice expressing a mutant of PDK1 incapable of binding phosphoinositides. The knock-in mice are significantly small, insulin resistant, and hyperinsulinemic. Activation of PKB is markedly reduced in knock-in mice as a result of lower phosphorylation of PKB at Thr308, the residue phosphorylated by PDK1. This results in the inhibition of the downstream mTOR complex 1 and S6K1 signaling pathways. In contrast, activation of SGK1 or p90 ribosomal S6 kinase or stimulation of S6K1 induced by feeding is unaffected by the PDK1 PH domain mutation. These observations establish the importance of the PDK1-phosphoinositide interaction in enabling PKB to be efficiently activated with an animal model. Our findings reveal how reduced activation of PKB isoforms impinges on downstream signaling pathways, causing diminution of size as well as insulin resistance.
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Bibliography. Current world literature. Growth and development. Curr Opin Endocrinol Diabetes Obes 2008; 15:79-101. [PMID: 18185067 DOI: 10.1097/med.0b013e3282f4f084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Föller M, Mahmud H, Koka S, Lang F. Reduced Ca2+ entry and suicidal death of erythrocytes in PDK1 hypomorphic mice. Pflugers Arch 2007; 455:939-49. [PMID: 17899170 DOI: 10.1007/s00424-007-0336-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 08/07/2007] [Accepted: 08/23/2007] [Indexed: 12/16/2022]
Abstract
The phosphoinositide-dependent kinase PDK1 is a key element in the phosphoinositol-3-kinase signalling pathway, which is involved in the regulation of ion channels, transporters, cell volume and cell survival. Eryptosis, the suicidal death of erythrocytes, is characterized by decrease in cell volume, cell membrane blebbing and phospholipids scrambling with phosphatidylserine exposure at the cell surface. Oxidative stress, osmotic shock or Cl- removal trigger eryptosis by activation of Ca2+-permeable cation channels and subsequent increase in cytosolic Ca2+ activity. To explore the impact of PDK1 for erythrocyte survival, eryptosis was analysed in hypomorphic mice (pdk1hm) expressing only some 25% of PDK1 and in their wild-type littermates (pdk1wt). Cell volume was estimated from forward scatter and phosphatidylserine exposure from annexin-V binding in fluorescence activated cell sorter analysis. Forward scatter was smaller in pdk1hm than in pdk1wt erythrocytes. Oxidative stress (100 microM tert-butylhydroperoxide), osmotic shock (+300 mM sucrose) and Cl- removal (replacement of Cl- with gluconate) all decreased forward scatter and increased the percentage of annexin-V-binding erythrocytes from both pdk1hm and pdk1wt mice. After treatment, the forward scatter was similar in both genotypes, but the percentage of annexin-V binding was significantly smaller in pdk1hm than in pdk1wt erythrocytes. According to Fluo-3 fluorescence, cytosolic Ca2+ activity was significantly smaller in pdk1hm than in pdk1wt erythrocytes. Treatment with Ca2+-ionophore ionomycin (1 microM) was followed by an increase in annexin-V binding to similar levels in pdk1hm and pdk1wt erythrocytes. The experiments reveal that PDK1 deficiency is associated with decreased Ca2+ entry into erythrocytes and thus with blunted eryptotic effects of oxidative stress, osmotic shock and Cl- removal.
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Affiliation(s)
- Michael Föller
- Department of Physiology, University of Tuebingen, Gmelinstr. 5, 72076 Tübingen, Germany
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