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Feng Q, Wang H, Shao Y, Xu X. Antizyme inhibitor family: biological and translational research implications. Cell Commun Signal 2024; 22:11. [PMID: 38169396 PMCID: PMC10762828 DOI: 10.1186/s12964-023-01445-1] [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: 05/10/2023] [Accepted: 12/18/2023] [Indexed: 01/05/2024] Open
Abstract
Metabolism of polyamines is of critical importance to physiological processes. Ornithine decarboxylase (ODC) antizyme inhibitors (AZINs) are capable of interacting with antizymes (AZs), thereby releasing ODC from ODC-AZs complex, and promote polyamine biosynthesis. AZINs regulate reproduction, embryonic development, fibrogenesis and tumorigenesis through polyamine and other signaling pathways. Dysregulation of AZINs has involved in multiple human diseases, especially malignant tumors. Adenosine-to-inosine (A-to-I) RNA editing is the most common type of post-transcriptional nucleotide modification in humans. Additionally, the high frequencies of RNA-edited AZIN1 in human cancers correlates with increase of cancer cell proliferation, enhancement of cancer cell stemness, and promotion of tumor angiogenesis. In this review, we summarize the current knowledge on the various contribution of AZINs related with potential cancer promotion, cancer stemness, microenvironment and RNA modification, especially underlying molecular mechanisms, and furthermore explored its promising implication for cancer diagnosis and treatment.
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Affiliation(s)
- Qiaohui Feng
- Department of Breast Surgery, The First Hospital of China Medical University, Shenyang, Liaoning, 110001, PR China
| | - Huijie Wang
- Department of Pathophysiology, College of Basic Medical Science, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, 110122, Liaoning Province, PR China
| | - Youcheng Shao
- Department of Pathophysiology, College of Basic Medical Science, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, 110122, Liaoning Province, PR China
| | - Xiaoyan Xu
- Department of Pathophysiology, College of Basic Medical Science, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, 110122, Liaoning Province, PR China.
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2
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Kang B, Wang X, An X, Ji C, Ling W, Qi Y, Li S, Jiang D. Polyamines in Ovarian Aging and Disease. Int J Mol Sci 2023; 24:15330. [PMID: 37895010 PMCID: PMC10607840 DOI: 10.3390/ijms242015330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 10/17/2023] [Accepted: 10/17/2023] [Indexed: 10/29/2023] Open
Abstract
Ovarian aging and disease-related decline in fertility are challenging medical and economic issues with an increasing prevalence. Polyamines are a class of polycationic alkylamines widely distributed in mammals. They are small molecules essential for cell growth and development. Polyamines alleviate ovarian aging through various biological processes, including reproductive hormone synthesis, cell metabolism, programmed cell death, etc. However, an abnormal increase in polyamine levels can lead to ovarian damage and promote the development of ovarian disease. Therefore, polyamines have long been considered potential therapeutic targets for aging and disease, but their regulatory roles in the ovary deserve further investigation. This review discusses the mechanisms by which polyamines ameliorate human ovarian aging and disease through different biological processes, such as autophagy and oxidative stress, to develop safe and effective polyamine targeted therapy strategies for ovarian aging and the diseases.
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Affiliation(s)
- Bo Kang
- State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (X.W.); (X.A.); (C.J.); (W.L.); (Y.Q.); (S.L.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Xin Wang
- State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (X.W.); (X.A.); (C.J.); (W.L.); (Y.Q.); (S.L.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Xiaoguang An
- State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (X.W.); (X.A.); (C.J.); (W.L.); (Y.Q.); (S.L.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Chengweng Ji
- State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (X.W.); (X.A.); (C.J.); (W.L.); (Y.Q.); (S.L.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Weikang Ling
- State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (X.W.); (X.A.); (C.J.); (W.L.); (Y.Q.); (S.L.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Yuxin Qi
- State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (X.W.); (X.A.); (C.J.); (W.L.); (Y.Q.); (S.L.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Shuo Li
- State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (X.W.); (X.A.); (C.J.); (W.L.); (Y.Q.); (S.L.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Dongmei Jiang
- State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (X.W.); (X.A.); (C.J.); (W.L.); (Y.Q.); (S.L.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
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Shi Q, Chen Q, Zhou Z, Zheng X, Huang X, Fang M, Hu Y, Song L, Yang H, Chen Q. Hypoxia-induced antizyme inhibitors 2 regulates cisplatin resistance through epithelia-mesenchymal transition pathway in non-small cell lung cancer. Pulm Pharmacol Ther 2021; 69:102048. [PMID: 34082109 DOI: 10.1016/j.pupt.2021.102048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 04/29/2021] [Accepted: 05/28/2021] [Indexed: 01/27/2023]
Abstract
Antizyme inhibitors 2 (AZIN2) was found to be associated with poor prognosis of patients with rectal cancer. However, no studies have reported whether AZIN2 functions in non-small cell lung cancer (NSCLC). This study aimed to investigate the role of AZIN2 in cisplatin (DDP) resistance in NSCLC. We established DDP resistant A549 and H1299 cell lines. The transcriptional and translational expression levels were examined using quantitative real-time polymerase chain reaction and western blot. Cell apoptosis was evaluated by caspase-3 activity and nucleosome ELISA assays. Luciferase reporter assay was employed to evaluate the impact of hypoxia-inducible factor (HIF-1α) on AZIN2 transcription. AZIN2 expression was found to be associated with DDP resistance and poor prognosis in patients with NSCLC. AZIN2 overexpression promoted cell viability, colony formation, and reduced cell apoptosis in H1299 cells and A549 upon DDP treatment. Correspondingly, AZIN2 knockdown significantly inhibited cell viability and colony formation, and increased cell apoptosis upon DDP treatment. Interestingly, AZIN2 expression in NSCLC cells was significantly induced by hypoxia condition. The occupancy of HIF-1α, an important regulator of the hypoxia response, remarkably enriched at the promoter region of AZIN2 under hypoxia condition. In addition, AZIN2 overexpression resulted in epithelial-mesenchymal transition (EMT). The results suggested that hypoxia-induced AZIN2 high expression may contribute to DDP resistance development by promoting the EMT.
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Affiliation(s)
- Qin Shi
- Department of Oncology, Fujian Fuzhou Pulmonary Hospital, No. 2 Shangdu Hubian, Cangshan District, Fuzhou, 350000, Fujian, China.
| | - Qiaolin Chen
- Department of Oncology, Fujian Fuzhou Pulmonary Hospital, No. 2 Shangdu Hubian, Cangshan District, Fuzhou, 350000, Fujian, China
| | - Zhan Zhou
- Department of Oncology, Fujian Fuzhou Pulmonary Hospital, No. 2 Shangdu Hubian, Cangshan District, Fuzhou, 350000, Fujian, China
| | - Xiuxia Zheng
- Department of Oncology, Fujian Fuzhou Pulmonary Hospital, No. 2 Shangdu Hubian, Cangshan District, Fuzhou, 350000, Fujian, China
| | - Xinhui Huang
- Department of Oncology, Fujian Fuzhou Pulmonary Hospital, No. 2 Shangdu Hubian, Cangshan District, Fuzhou, 350000, Fujian, China
| | - Minshan Fang
- Department of Oncology, Fujian Fuzhou Pulmonary Hospital, No. 2 Shangdu Hubian, Cangshan District, Fuzhou, 350000, Fujian, China
| | - Ying Hu
- Department of Oncology, Fujian Fuzhou Pulmonary Hospital, No. 2 Shangdu Hubian, Cangshan District, Fuzhou, 350000, Fujian, China
| | - Li Song
- Department of Oncology, Fujian Fuzhou Pulmonary Hospital, No. 2 Shangdu Hubian, Cangshan District, Fuzhou, 350000, Fujian, China
| | - Hualing Yang
- Department of Oncology, Fujian Fuzhou Pulmonary Hospital, No. 2 Shangdu Hubian, Cangshan District, Fuzhou, 350000, Fujian, China
| | - Qun Chen
- Department of Oncology, Fujian Fuzhou Pulmonary Hospital, No. 2 Shangdu Hubian, Cangshan District, Fuzhou, 350000, Fujian, China.
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Tulluri V, Nemmara VV. Role of Antizyme Inhibitor Proteins in Cancers and Beyond. Onco Targets Ther 2021; 14:667-682. [PMID: 33531815 PMCID: PMC7846877 DOI: 10.2147/ott.s281157] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/05/2020] [Indexed: 01/30/2023] Open
Abstract
Polyamines are multivalent organic cations essential for many cellular functions, including cell growth, differentiation, and proliferation. However, elevated polyamine levels are associated with a slew of pathological conditions, including multiple cancers. Intracellular polyamine levels are primarily controlled by the autoregulatory circuit comprising two different protein types, Antizymes (OAZ) and Antizyme Inhibitors (AZIN), which regulate the activity of the polyamine biosynthetic enzyme ornithine decarboxylase (ODC). While OAZ functions to decrease the intracellular polyamine levels by inhibiting ODC activity and exerting a negative control of polyamine uptake, AZIN operates to increase intracellular polyamine levels by binding and sequestering OAZ to relieve ODC inhibition and to increase polyamine uptake. Interestingly, OAZ and AZIN exhibit autoregulatory functions on polyamine independent pathways as well. A growing body of evidence demonstrates the dysregulation of AZIN expression in multiple cancers. Additionally, RNA editing of the Azin1 transcript results in a "gain-of-function" phenotype, which is shown to drive aggressive tumor types. This review will discuss the recent advances in AZIN's role in cancers via aberrant polyamine upregulation and its polyamine-independent protein regulation. This report will also highlight AZIN interaction with proteins outside the polyamine biosynthetic pathway and its potential implication to cancer pathogenesis. Finally, this review will reveal the protein interaction network of AZIN isoforms by analyzing three different interactome databases.
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Affiliation(s)
- Vennela Tulluri
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ08028, USA
| | - Venkatesh V Nemmara
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ08028, USA
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Sánchez-Jiménez F, Medina MÁ, Villalobos-Rueda L, Urdiales JL. Polyamines in mammalian pathophysiology. Cell Mol Life Sci 2019; 76:3987-4008. [PMID: 31227845 PMCID: PMC11105599 DOI: 10.1007/s00018-019-03196-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 06/11/2019] [Accepted: 06/14/2019] [Indexed: 02/07/2023]
Abstract
Polyamines (PAs) are essential organic polycations for cell viability along the whole phylogenetic scale. In mammals, they are involved in the most important physiological processes: cell proliferation and viability, nutrition, fertility, as well as nervous and immune systems. Consequently, altered polyamine metabolism is involved in a series of pathologies. Due to their pathophysiological importance, PA metabolism has evolved to be a very robust metabolic module, interconnected with the other essential metabolic modules for gene expression and cell proliferation/differentiation. Two different PA sources exist for animals: PA coming from diet and endogenous synthesis. In the first section of this work, the molecular characteristics of PAs are presented as determinant of their roles in living organisms. In a second section, the metabolic specificities of mammalian PA metabolism are reviewed, as well as some obscure aspects on it. This second section includes information on mammalian cell/tissue-dependent PA-related gene expression and information on crosstalk with the other mammalian metabolic modules. The third section presents a synthesis of the physiological processes described as modulated by PAs in humans and/or experimental animal models, the molecular bases of these regulatory mechanisms known so far, as well as the most important gaps of information, which explain why knowledge around the specific roles of PAs in human physiology is still considered a "mysterious" subject. In spite of its robustness, PA metabolism can be altered under different exogenous and/or endogenous circumstances so leading to the loss of homeostasis and, therefore, to the promotion of a pathology. The available information will be summarized in the fourth section of this review. The different sections of this review also point out the lesser-known aspects of the topic. Finally, future prospects to advance on these still obscure gaps of knowledge on the roles on PAs on human physiopathology are discussed.
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Affiliation(s)
- Francisca Sánchez-Jiménez
- Departamento de Biología Molecular y Bioquímica, Facultad de Ciencias, Universidad de Málaga, Andalucía Tech, and IBIMA (Biomedical Research Institute of Málaga), Málaga, Spain
- UNIT 741, CIBER de Enfermedades Raras (CIBERER), 29071, Málaga, Spain
| | - Miguel Ángel Medina
- Departamento de Biología Molecular y Bioquímica, Facultad de Ciencias, Universidad de Málaga, Andalucía Tech, and IBIMA (Biomedical Research Institute of Málaga), Málaga, Spain
- UNIT 741, CIBER de Enfermedades Raras (CIBERER), 29071, Málaga, Spain
| | - Lorena Villalobos-Rueda
- Departamento de Biología Molecular y Bioquímica, Facultad de Ciencias, Universidad de Málaga, Andalucía Tech, and IBIMA (Biomedical Research Institute of Málaga), Málaga, Spain
| | - José Luis Urdiales
- Departamento de Biología Molecular y Bioquímica, Facultad de Ciencias, Universidad de Málaga, Andalucía Tech, and IBIMA (Biomedical Research Institute of Málaga), Málaga, Spain.
- UNIT 741, CIBER de Enfermedades Raras (CIBERER), 29071, Málaga, Spain.
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The protective role of spermine against male reproductive aberrations induced by exposure to electromagnetic field – An experimental investigation in the rat. Toxicol Appl Pharmacol 2019; 370:117-130. [DOI: 10.1016/j.taap.2019.03.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 02/25/2019] [Accepted: 03/12/2019] [Indexed: 12/15/2022]
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Ornithine decarboxylase antizyme inhibitor 2 (AZIN2) is a signature of secretory phenotype and independent predictor of adverse prognosis in colorectal cancer. PLoS One 2019; 14:e0211564. [PMID: 30768610 PMCID: PMC6377119 DOI: 10.1371/journal.pone.0211564] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Accepted: 01/16/2019] [Indexed: 12/27/2022] Open
Abstract
Ornithine decarboxylase (ODC) is the rate-limiting enzyme of polyamine synthesis. The two ODC antizyme inhibitors (AZIN1) and (AZIN2) are regulators of the catalytic activity of ODC. While AZIN1 is a regulator of cell proliferation, AZIN2 is involved in intracellular vesicle transport and secretion. There are no previous reports on the impact of AZIN2 expression in human cancer. We applied immunohistochemistry with antibodies to human AZIN2 on tissue micro- arrays of colorectal cancers (CRC) from 840 patients with a median follow-up of 5.1 years (range 0-25.8). The 5-year disease-specific survival rate was 58.9% (95% Cl 55.0-62.8%). High AZIN2 expression was associated with mucinous histology (p = 0.002) and location in the right hemicolon (p = 0.021). We found no association with age, gender, stage, or histological tumor grade. High tumor expression of AZIN2 predicted an unfavorable prognosis (p<0.0001, log-rank test), compared to low AZIN2 expression. Cox multivariable analysis identified AZIN2 as an independent factor of an unfavorable prognosis in CRC. The strongest AZIN2 expression was seen in invasive tumor cells having morphological features of epithelial-mesenchymal transition (EMT). Induction of EMT in HT-29 CRC cells lead to upregulated expression of endogenous AZIN2. Given that AZIN2 is a regulator of vesicle transport and secretion, we overexpressed human AZIN2 cDNA in T84 CRC cells, and found strongly enhanced accumulation of CD63-positive exosomes in the culture medium. These findings indicate that AZIN2 expression is a signature of EMT-associated secretory phenotype that is linked to an adverse prognosis in CRC.
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New insights of polyamine metabolism in testicular physiology: A role of ornithine decarboxylase antizyme inhibitor 2 (AZIN2) in the modulation of testosterone levels and sperm motility. PLoS One 2018; 13:e0209202. [PMID: 30566531 PMCID: PMC6300296 DOI: 10.1371/journal.pone.0209202] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 12/01/2018] [Indexed: 12/19/2022] Open
Abstract
The specific role of polyamines in the testis physiology is not fully understood. Antizymes (OAZs) and antizyme inhibitors (AZINs) are modulators of ornithine decarboxylase (ODC), a key enzyme in polyamine biosynthesis and polyamine uptake. Although the three known OAZs are expressed in the testis, only OAZ3 is testis specific and has been proven to have an essential role in male fertility. Regarding the two existing AZINs, AZIN2 is the most abundantly expressed member in this gonad. Whereas previous studies suggested that AZIN2 might participate in mouse spermatogenesis, immunohistological analysis of human testicular sections revealed that AZIN2 is also detected in the steroidogenic Leydig cells but not in the germinal epithelium. In the present study, we found a close ontogenic similarity in the mRNA levels of OAZs and AZINs between mice and rats, but an opposite expression pattern of ODC activity. Further analysis of AZIN2 and OAZ3 in the testis of mice with different alterations in spermatogenesis and fertility, induced either genetically or pharmacologically, corroborated that both AZIN2 and OAZ3 are mainly expressed in the haploid germinal cells. Finally, by using transgenic mice with a truncated Azin2 gene fused to the bacterial lacZ gene, we studied the expression of Azin2 in testes, epididymides and spermatozoa. AZIN2 was detected in spermatids and spermatozoa, as well as in Leydig cells, and in epithelial epidydimal cells. Azin2 knock-out male mice were fertile; however, they showed marked decreases in testicular putrescine and plasma and testicular testosterone levels, and a dramatic reduction in the sperm motility. These results suggest an important role for AZIN2 in testicular cells by modulating polyamine concentrations, testosterone synthesis and sperm function. Overall, our data corroborate the relevance of polyamine regulation in testis functions, where both AZIN2 and OAZ3 play fundamental roles.
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Abstract
The polyamines spermidine, spermine, and their precursor putrescine are organic polycations involved in various cellular processes and are absolutely essential for cellular proliferation. Because of their crucial function in the cell, their intracellular concentration must be maintained at optimal levels. To a large extent, this regulation is achieved through the activity of an autoregulatory loop that involves two proteins, antizyme (Az) and antizyme inhibitor (AzI), that regulate the first enzyme in polyamine biosynthesis, ornithine decarboxylase (ODC), and polyamine uptake activity in response to intracellular polyamine levels. In this Minireview, I will discuss what has been learned about the mechanism of Az expression and its physical interaction with both ODC and AzI in the regulation of polyamines.
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Affiliation(s)
- Chaim Kahana
- From the Department of Molecular Genetics, the Weizmann Institute of Science, Rehovot 76100, Israel
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Ramos-Molina B, Lambertos A, Peñafiel R. Antizyme Inhibitors in Polyamine Metabolism and Beyond: Physiopathological Implications. ACTA ACUST UNITED AC 2018; 6:medsci6040089. [PMID: 30304856 PMCID: PMC6313458 DOI: 10.3390/medsci6040089] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Revised: 10/02/2018] [Accepted: 10/04/2018] [Indexed: 12/25/2022]
Abstract
The intracellular levels of polyamines, cationic molecules involved in a myriad of cellular functions ranging from cellular growth, differentiation and apoptosis, is precisely regulated by antizymes and antizyme inhibitors via the modulation of the polyamine biosynthetic and transport systems. Antizymes, which are mainly activated upon high polyamine levels, inhibit ornithine decarboxylase (ODC), the key enzyme of the polyamine biosynthetic route, and exert a negative control of polyamine intake. Antizyme inhibitors (AZINs), which are proteins highly homologous to ODC, selectively interact with antizymes, preventing their action on ODC and the polyamine transport system. In this review, we will update the recent advances on the structural, cellular and physiological functions of AZINs, with particular emphasis on the action of these proteins in the regulation of polyamine metabolism. In addition, we will describe emerging evidence that suggests that AZINs may also have polyamine-independent effects on cells. Finally, we will discuss how the dysregulation of AZIN activity has been implicated in certain human pathologies such as cancer, fibrosis or neurodegenerative diseases.
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Affiliation(s)
- Bruno Ramos-Molina
- Department of Biochemistry and Molecular Biology B and Immunology, Faculty of Medicine, University of Murcia, 30100 Murcia, Spain.
- Laboratory of Cellular and Molecular Endocrinology, Institute of Biomedical Research in Malaga (IBIMA), Virgen de la Victoria University Hospital, 29010 Málaga, Spain.
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), Institute of Health Carlos III (ISCIII), 28029 Madrid, Spain.
| | - Ana Lambertos
- Department of Biochemistry and Molecular Biology B and Immunology, Faculty of Medicine, University of Murcia, 30100 Murcia, Spain.
- Biomedical Research Institute of Murcia (IMIB), 30120 Murcia, Spain.
| | - Rafael Peñafiel
- Department of Biochemistry and Molecular Biology B and Immunology, Faculty of Medicine, University of Murcia, 30100 Murcia, Spain.
- Biomedical Research Institute of Murcia (IMIB), 30120 Murcia, Spain.
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Lambertos A, Ramos-Molina B, Cerezo D, López-Contreras AJ, Peñafiel R. The mouse Gm853 gene encodes a novel enzyme: Leucine decarboxylase. Biochim Biophys Acta Gen Subj 2017; 1862:365-376. [PMID: 29108956 DOI: 10.1016/j.bbagen.2017.11.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 10/31/2017] [Accepted: 11/02/2017] [Indexed: 12/18/2022]
Abstract
Ornithine decarboxylase (ODC) is a key enzyme in the biosynthesis of polyamines. ODC-antizyme inhibitors (AZINs) are homologous proteins of ODC, devoid of enzymatic activity but acting as regulators of polyamine levels. The last paralogue gene recently incorporated into the ODC/AZINs family is the murine Gm853, which is located in the same chromosome as AZIN2, and whose biochemical function is still unknown. By means of transfection assays of HEK293T cells with a plasmid containing the coding region of Gm853, we show here that unlike ODC, GM853 was a stable protein that was not able to decarboxylate l-ornithine or l-lysine and that did not act as an antizyme inhibitor. However, GM853 showed leucine decarboxylase activity, an enzymatic activity never described in animal cells, and by acting on l-leucine (Km=7.03×10-3M) it produced isopentylamine, an aliphatic monoamine with unknown function. The other physiological branched-chain amino acids, l-valine and l-isoleucine were poor substrates of the enzyme. Gm853 expression was mainly detected in the kidney, and as Odc, it was stimulated by testosterone. The conservation of Gm853 orthologues in different mammalian species, including primates, underlines the possible biological significance of this new enzyme. In this study, we describe for the first time a mammalian enzyme with leucine decarboxylase activity, therefore proposing that the gene Gm853 and its protein product should be named as leucine decarboxylase (Ldc, LDC).
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Affiliation(s)
- Ana Lambertos
- Department of Biochemistry and Molecular Biology B and Immunology, Faculty of Medicine, University of Murcia, Spain; Instituto Murciano de Investigación Biosanitaria (IMIB), Murcia, Spain
| | - Bruno Ramos-Molina
- Department of Biochemistry and Molecular Biology B and Immunology, Faculty of Medicine, University of Murcia, Spain
| | - David Cerezo
- Department of Biochemistry and Molecular Biology B and Immunology, Faculty of Medicine, University of Murcia, Spain
| | - Andrés J López-Contreras
- Department of Biochemistry and Molecular Biology B and Immunology, Faculty of Medicine, University of Murcia, Spain
| | - Rafael Peñafiel
- Department of Biochemistry and Molecular Biology B and Immunology, Faculty of Medicine, University of Murcia, Spain; Instituto Murciano de Investigación Biosanitaria (IMIB), Murcia, Spain.
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Expression of ODC Antizyme Inhibitor 2 (AZIN2) in Human Secretory Cells and Tissues. PLoS One 2016; 11:e0151175. [PMID: 26963840 PMCID: PMC4786150 DOI: 10.1371/journal.pone.0151175] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 02/24/2016] [Indexed: 01/18/2023] Open
Abstract
Ornithine decarboxylase (ODC) antizyme inhibitor 2 (AZIN2), originally called ODCp, is a regulator of polyamine synthesis that we originally identified and cloned. High expression of ODCp mRNA was found in brain and testis. We reported that AZIN2 is involved in regulation of cellular vesicle transport and / or secretion, but the ultimate physiological role(s) of AZIN2 is still poorly understood. In this study we used a peptide antibody (K3) to human AZIN2 and by immunohistochemistry mapped its expression in various normal tissues. We found high expression in the nervous system, in type 2 pneumocytes in the lung, in megakaryocytes, in gastric parietal cells co-localized with H,K-ATPase beta subunit, in selected enteroendocrine cells, in acinar cells of sweat glands, in podocytes, in macula densa cells and epithelium of collecting ducts in the kidney. The high expression of AZIN2 in various cells with secretory or vesicle transport activity indicates that the polyamine metabolism regulated by AZIN2 is more significantly involved in these events than previously appreciated.
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Greenwood MP, Greenwood M, Paton JFR, Murphy D. Control of Polyamine Biosynthesis by Antizyme Inhibitor 1 Is Important for Transcriptional Regulation of Arginine Vasopressin in the Male Rat Hypothalamus. Endocrinology 2015; 156:2905-17. [PMID: 25961839 PMCID: PMC4511134 DOI: 10.1210/en.2015-1074] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The polyamines spermidine and spermine are small cations present in all living cells. In the brain, these cations are particularly abundant in the neurons of the paraventricular (PVN) and supraoptic nuclei (SON) of the hypothalamus, which synthesize the neuropeptide hormones arginine vasopressin (AVP) and oxytocin. We recently reported increased mRNA expression of antizyme inhibitor 1 (Azin1), an important regulator of polyamine synthesis, in rat SON and PVN as a consequence of 3 days of dehydration. Here we show that AZIN1 protein is highly expressed in both AVP- and oxytocin-positive magnocellular neurons of the SON and PVN together with antizyme 1 (AZ1), ornithine decarboxylase, and polyamines. Azin1 mRNA expression increased in the SON and PVN as a consequence of dehydration, salt loading, and acute hypertonic stress. In organotypic hypothalamic cultures, addition of the irreversible ornithine decarboxylase inhibitor DL-2-(difluoromethyl)-ornithine hydrochloride significantly increased the abundance of heteronuclear AVP but not heteronuclear oxytocin. To identify the function of Azin1 in vivo, lentiviral vectors that either overexpress or knock down Azin1 were stereotaxically delivered into the SON and/or PVN. Azin1 short hairpin RNA delivery resulted in decreased plasma osmolality and had a significant effect on food intake. The expression of AVP mRNA was also significantly increased in the SON by Azin1 short hairpin RNA. In contrast, Azin1 overexpression in the SON decreased AVP mRNA expression. We have therefore identified AZIN1, and hence by inference, polyamines as novel regulators of the expression of the AVP gene.
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Affiliation(s)
- Michael P Greenwood
- School of Clinical Sciences (M.P.G., M.G., D.M.), University of Bristol, Bristol BS1 3NY, United Kingdom; School of Physiology and Pharmacology (J.F.R.P.), University of Bristol, Bristol BS8 1TD, United Kingdom; and Department of Physiology (D.M.), University of Malaya, Kuala Lumpur, Malaysia 50603
| | - Mingkwan Greenwood
- School of Clinical Sciences (M.P.G., M.G., D.M.), University of Bristol, Bristol BS1 3NY, United Kingdom; School of Physiology and Pharmacology (J.F.R.P.), University of Bristol, Bristol BS8 1TD, United Kingdom; and Department of Physiology (D.M.), University of Malaya, Kuala Lumpur, Malaysia 50603
| | - Julian F R Paton
- School of Clinical Sciences (M.P.G., M.G., D.M.), University of Bristol, Bristol BS1 3NY, United Kingdom; School of Physiology and Pharmacology (J.F.R.P.), University of Bristol, Bristol BS8 1TD, United Kingdom; and Department of Physiology (D.M.), University of Malaya, Kuala Lumpur, Malaysia 50603
| | - David Murphy
- School of Clinical Sciences (M.P.G., M.G., D.M.), University of Bristol, Bristol BS1 3NY, United Kingdom; School of Physiology and Pharmacology (J.F.R.P.), University of Bristol, Bristol BS8 1TD, United Kingdom; and Department of Physiology (D.M.), University of Malaya, Kuala Lumpur, Malaysia 50603
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Ramos-Molina B, López-Contreras AJ, Lambertos A, Dardonville C, Cremades A, Peñafiel R. Influence of ornithine decarboxylase antizymes and antizyme inhibitors on agmatine uptake by mammalian cells. Amino Acids 2015; 47:1025-34. [PMID: 25655388 DOI: 10.1007/s00726-015-1931-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 01/24/2015] [Indexed: 10/24/2022]
Abstract
Agmatine (4-aminobutylguanidine), a dicationic molecule at physiological pH, exerts relevant modulatory actions at many different molecular target sites in mammalian cells, having been suggested that the administration of this compound may have therapeutic interest. Several plasma membrane transporters have been implicated in agmatine uptake by mammalian cells. Here we report that in kidney-derived COS-7 cell line, at physiological agmatine levels, the general polyamine transporter participates in the plasma membrane translocation of agmatine, with an apparent Km of 44 ± 7 µM and Vmax of 17.3 ± 3.3 nmol h(-1) mg(-1) protein, but that at elevated concentrations, agmatine can be also taken up by other transport systems. In the first case, the physiological polyamines (putrescine, spermidine and spermine), several diguanidines and bis(2-aminoimidazolines) and the polyamine transport inhibitor AMXT-1501 markedly decreased agmatine uptake. In cells transfected with any of the three ornithine decarboxylase antizymes (AZ1, AZ2 and AZ3), agmatine uptake was dramatically reduced. On the contrary, transfection with antizyme inhibitors (AZIN1 and AZIN2) markedly increased the transport of agmatine. Furthermore, whereas putrescine uptake was significantly decreased in cells transfected with ornithine decarboxylase (ODC), the accumulation of agmatine was stimulated, suggesting a trans-activating effect of intracellular putrescine on agmatine uptake. All these results indicate that ODC and its regulatory proteins (antizymes and antizyme inhibitors) may influence agmatine homeostasis in mammalian tissues.
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Affiliation(s)
- Bruno Ramos-Molina
- Departamento de Bioquímica y Biología Molecular B e Inmunología, Facultad de Medicina, Universidad de Murcia, Campus de Espinardo, 30100, Murcia, Spain
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15
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Ramos-Molina B, Lambertos A, Lopez-Contreras AJ, Kasprzak JM, Czerwoniec A, Bujnicki JM, Cremades A, Peñafiel R. Structural and degradative aspects of ornithine decarboxylase antizyme inhibitor 2. FEBS Open Bio 2014; 4:510-21. [PMID: 24967154 PMCID: PMC4066113 DOI: 10.1016/j.fob.2014.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 05/23/2014] [Accepted: 05/27/2014] [Indexed: 01/11/2023] Open
Abstract
Ornithine decarboxylase (ODC) is the key enzyme in the polyamine biosynthetic pathway. ODC levels are controlled by polyamines through the induction of antizymes (AZs), small proteins that inhibit ODC and target it to proteasomal degradation without ubiquitination. Antizyme inhibitors (AZIN1 and AZIN2) are proteins homologous to ODC that bind to AZs and counteract their negative effect on ODC. Whereas ODC and AZIN1 are well-characterized proteins, little is known on the structure and stability of AZIN2, the lastly discovered member of this regulatory circuit. In this work we first analyzed structural aspects of AZIN2 by combining biochemical and computational approaches. We demonstrated that AZIN2, in contrast to ODC, does not form homodimers, although the predicted tertiary structure of the AZIN2 monomer was similar to that of ODC. Furthermore, we identified conserved residues in the antizyme-binding element, whose substitution drastically affected the capacity of AZIN2 to bind AZ1. On the other hand, we also found that AZIN2 is much more labile than ODC, but it is highly stabilized by its binding to AZs. Interestingly, the administration of the proteasome inhibitor MG132 caused differential effects on the three AZ-binding proteins, having no effect on ODC, preventing the degradation of AZIN1, but unexpectedly increasing the degradation of AZIN2. Inhibitors of the lysosomal function partially prevented the effect of MG132 on AZIN2. These results suggest that the degradation of AZIN2 could be also mediated by an alternative route to that of proteasome. These findings provide new relevant information on this unique regulatory mechanism of polyamine metabolism.
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Key Words
- AZ, antizyme
- AZBE, antizyme-binding element
- AZIN, antizyme inhibitor
- Antizyme
- Antizyme-binding element
- ERGIC, endoplasmic reticulum-Golgi intermediate compartment
- GDT_TS, global distance test total score
- HA, hemagglutinin
- HEK, human embryonic kidney
- Homology modeling
- ODC, ornithine decarboxylase
- PAGE, polyacrylamide gel electrophoresis
- Polyamines
- Proteasome inhibitors
- Protein degradation
- RMSD, root-mean-square deviation
- TGN, trans-Golgi network
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Affiliation(s)
- Bruno Ramos-Molina
- Department of Biochemistry and Molecular Biology B and Immunology, University of Murcia, Spain ; Instituto Murciano de Investigación Biosanitaria (IMIB), Murcia, Spain
| | - Ana Lambertos
- Department of Biochemistry and Molecular Biology B and Immunology, University of Murcia, Spain ; Instituto Murciano de Investigación Biosanitaria (IMIB), Murcia, Spain
| | | | - Joanna M Kasprzak
- Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznan, Poland
| | - Anna Czerwoniec
- Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznan, Poland
| | - Janusz M Bujnicki
- International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Asunción Cremades
- Department of Biochemistry and Molecular Biology B and Immunology, University of Murcia, Spain ; Instituto Murciano de Investigación Biosanitaria (IMIB), Murcia, Spain
| | - Rafael Peñafiel
- Department of Biochemistry and Molecular Biology B and Immunology, University of Murcia, Spain ; Instituto Murciano de Investigación Biosanitaria (IMIB), Murcia, Spain
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16
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López-Garcia C, Ramos-Molina B, Lambertos A, López-Contreras AJ, Cremades A, Peñafiel R. Antizyme inhibitor 2 hypomorphic mice. New patterns of expression in pancreas and adrenal glands suggest a role in secretory processes. PLoS One 2013; 8:e69188. [PMID: 23874910 PMCID: PMC3709932 DOI: 10.1371/journal.pone.0069188] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 06/07/2013] [Indexed: 01/21/2023] Open
Abstract
The intracellular levels of polyamines, polycations implicated in proliferation, differentiation and cell survival, are regulated by controlling their biosynthesis, catabolism and transport. Antizymes and antizyme inhibitors are key regulatory proteins of polyamine levels by affecting ornithine decarboxylase, the rate-limiting biosynthetic enzyme, and polyamine uptake. We recently described the molecular function of a novel antizyme inhibitor (AZIN2). However, the physiological function of AZIN2 in mammals is mostly unknown. To gain insight on the tissue expression profile of AZIN2 and to find its possible physiological role, we have generated, transgenic mice with severe Azin2 hypomorphism. This mouse model expresses transgenic bacterial β-D-galactosidase as a reporter gene, under the control of the Azin2 endogenous promoter, what allows a very sensitive and specific detection of the expression of the gene in the different tissues of transgenic mice. The biochemical and histochemical analyses of β-D-galactosidase together with the quantification of Azin2 mRNA levels, corroborated that AZIN2 is mainly expressed in testis and brain, and showed for the first time that AZIN2 is also expressed in the adrenal glands and pancreas. In these tissues, AZIN2 was not expressed in all type of cells, but rather in specific type of cells. Thus, AZIN2 was mainly found in the haploid germinal cells of the testis and in different brain regions such as hippocampus and cerebellum, particularly in specific type of neurons. In the adrenal glands and pancreas, the expression was restricted to the adrenal medulla and to the Langerhans islets, respectively. Interestingly, plasma insulin levels were significantly reduced in the transgenic mice. These results support the idea that AZIN2 may have a role in the modulation of reproductory and secretory functions and that this mouse model might be an interesting tool for the progress of our understanding on the role of AZIN2 and polyamines in specific mammalian cells.
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Affiliation(s)
- Carlos López-Garcia
- Department of Biochemistry and Molecular Biology B and Immunology, School of Medicine, University of Murcia, Murcia, Spain
| | - Bruno Ramos-Molina
- Department of Biochemistry and Molecular Biology B and Immunology, School of Medicine, University of Murcia, Murcia, Spain
| | - Ana Lambertos
- Department of Biochemistry and Molecular Biology B and Immunology, School of Medicine, University of Murcia, Murcia, Spain
| | | | - Asunción Cremades
- Department of Pharmacology, School of Medicine, University of Murcia, Murcia, Spain
- Instituto Murciano de Investigación Biosanitaria (IMIB), Murcia, Spain
| | - Rafael Peñafiel
- Department of Biochemistry and Molecular Biology B and Immunology, School of Medicine, University of Murcia, Murcia, Spain
- Instituto Murciano de Investigación Biosanitaria (IMIB), Murcia, Spain
- * E-mail:
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17
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Abstract
The polyamines are ubiquitous polycationic compounds. Over the past 40 yr, investigation has shown that some of these, namely spermine, spermidine, and putrescine, are essential to male and female reproductive processes and to embryo/fetal development. Indeed, their absence is characterized by infertility and arrest in embryogenesis. Mammals synthesize polyamines de novo from amino acids or import these compounds from the diet. Information collected recently has shown that polyamines are essential regulators of cell growth and gene expression, and they have been implicated in both mitosis and meiosis. In male reproduction, polyamine expression correlates with stages of spermatogenesis, and polyamines appear to function in promoting sperm motility. There is evidence for polyamine involvement in ovarian follicle development and ovulation in female mammals, and polyamine synthesis is required for steroidogenesis in the ovary. Studies of the embryo indicate a polyamine requirement that can be met from maternal sources before implantation, whereas elimination of polyamine synthesis abrogates embryo development at gastrulation. Polyamines play roles in embryo implantation, in decidualization, and in placental formation and function, and polyamine privation during gestation results in intrauterine growth retardation. Emerging information implicates dietary arginine and dietary polyamines as nutritional regulators of fertility. The mechanisms by which polyamines regulate these multiple and diverse processes are not yet well explored; thus, there is fertile ground for further productive investigation.
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Affiliation(s)
- Pavine L C Lefèvre
- Centre de Recherche en Reproduction Animale, Faculté de Médecine Vétérinaire, Université de Montréal, 3200 rue Sicotte, Saint-Hyacinthe, Canada QC J2S 2M2
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Ivanov IP, Firth AE, Atkins JF. Recurrent Emergence of Catalytically Inactive Ornithine Decarboxylase Homologous Forms That Likely Have Regulatory Function. J Mol Evol 2010; 70:289-302. [DOI: 10.1007/s00239-010-9331-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 02/17/2010] [Indexed: 10/19/2022]
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Kanerva K, Mäkitie LT, Bäck N, Andersson LC. Ornithine decarboxylase antizyme inhibitor 2 regulates intracellular vesicle trafficking. Exp Cell Res 2010; 316:1896-906. [PMID: 20188728 DOI: 10.1016/j.yexcr.2010.02.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Revised: 02/18/2010] [Accepted: 02/19/2010] [Indexed: 11/25/2022]
Abstract
Antizyme inhibitor 1 (AZIN1) and 2 (AZIN2) are proteins that activate ornithine decarboxylase (ODC), the key enzyme of polyamine biosynthesis. Both AZINs release ODC from its inactive complex with antizyme (AZ), leading to formation of the catalytically active ODC. The ubiquitously expressed AZIN1 is involved in cell proliferation and transformation whereas the role of the recently found AZIN2 in cellular functions is unknown. Here we report the intracellular localization of AZIN2 and present novel evidence indicating that it acts as a regulator of vesicle trafficking. We used immunostaining to demonstrate that both endogenous and FLAG-tagged AZIN2 localize to post-Golgi vesicles of the secretory pathway. Immuno-electron microscopy revealed that the vesicles associate mainly with the trans-Golgi network (TGN). RNAi-mediated knockdown of AZIN2 or depletion of cellular polyamines caused selective fragmentation of the TGN and retarded the exocytotic release of vesicular stomatitis virus glycoprotein. Exogenous addition of polyamines normalized the morphological changes and reversed the inhibition of protein secretion. Our findings demonstrate that AZIN2 regulates the transport of secretory vesicles by locally activating ODC and polyamine biosynthesis.
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Affiliation(s)
- Kristiina Kanerva
- Department of Pathology, Haartman Institute, University of Helsinki, Helsinki, Finland
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20
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Extending the knowledge in histochemistry and cell biology. Histochem Cell Biol 2009; 133:1-40. [PMID: 19946696 DOI: 10.1007/s00418-009-0665-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2009] [Indexed: 01/21/2023]
Abstract
Central to modern Histochemistry and Cell Biology stands the need for visualization of cellular and molecular processes. In the past several years, a variety of techniques has been achieved bridging traditional light microscopy, fluorescence microscopy and electron microscopy with powerful software-based post-processing and computer modeling. Researchers now have various tools available to investigate problems of interest from bird's- up to worm's-eye of view, focusing on tissues, cells, proteins or finally single molecules. Applications of new approaches in combination with well-established traditional techniques of mRNA, DNA or protein analysis have led to enlightening and prudent studies which have paved the way toward a better understanding of not only physiological but also pathological processes in the field of cell biology. This review is intended to summarize articles standing for the progress made in "histo-biochemical" techniques and their manifold applications.
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Mäkitie LT, Kanerva K, Polvikoski T, Paetau A, Andersson LC. Brain neurons express ornithine decarboxylase-activating antizyme inhibitor 2 with accumulation in Alzheimer's disease. Brain Pathol 2009; 20:571-80. [PMID: 19832840 DOI: 10.1111/j.1750-3639.2009.00334.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Polyamines are small cationic molecules that in adult brain are connected to neuronal signaling by regulating inward-rectifier K(+)-channels and different glutamate receptors. Antizyme inhibitors (AZINs) regulate the cellular uptake of polyamines and activate ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine synthesis. Elevated levels of ODC activity and polyamines are detected in various brain disorders including stroke and Alzheimer's disease (AD). We originally reported a novel brain- and testis-specific AZIN, called AZIN2, the distribution of which we have now studied in normal and diseased human brain by in situ hybridization and immunohistochemistry. We found the highest accumulation of AZIN2 in a pearl-on-the-string-like distribution along the axons in both the white and gray matter. AZIN2 was also detected in a vesicle-like distribution in the somas of selected cortical pyramidal neurons. Double-immunofluorescence staining revealed co-localization of AZIN2 and N-methyl D-aspartate-type glutamate receptors (NMDARs) in pyramidal neurons of the cortex. Moreover, we found accumulation of AZIN2 in brains affected by AD, but not by other neurodegenerative disorders (CADASIL or Lewy body disease). ODC activity is mostly linked to cell proliferation, whereas its regulation by AZIN2 in post-mitotically differentiated neurons of the brain apparently serves different purposes. The subcellular distribution of AZIN2 suggests a role in vesicular trafficking.
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Affiliation(s)
- Laura T Mäkitie
- Department of Pathology, Haartman Institute, University of Helsinki, Helsinki, Finland
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