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Forbord KM, Okla M, Lunde NN, Bosnjak-Olsen T, Arnekleiv G, Hesselson D, Johansen HT, Tang JCY, Kassem M, Solberg R, Jafari A. The Cysteine Protease Legumain Is Upregulated by Vitamin D and Is a Regulator of Vitamin D Metabolism in Mice. Cells 2023; 13:36. [PMID: 38201240 PMCID: PMC10778535 DOI: 10.3390/cells13010036] [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: 11/22/2023] [Revised: 12/12/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
Legumain is a lysosomal cysteine protease that has been implicated in an increasing amount of physiological and pathophysiological processes. However, the upstream mechanisms regulating the expression and function of legumain are not well understood. Here, we provide in vitro and in vivo data showing that vitamin D3 (VD3) enhances legumain expression and function. In turn, legumain alters VD3 bioavailability, possibly through proteolytic cleavage of vitamin D binding protein (VDBP). Active VD3 (1,25(OH)2D3) increased legumain expression, activity, and secretion in osteogenic cultures of human bone marrow stromal cells. Upregulation of legumain was also observed in vivo, evidenced by increased legumain mRNA in the liver and spleen, as well as increased legumain activity in kidneys from wild-type mice treated with 25(OH)D3 (50 µg/kg, subcutaneously) for 8 days compared to a control. In addition, the serum level of legumain was also increased. We further showed that active legumain cleaved purified VDBP (55 kDa) in vitro, forming a 45 kDa fragment. In vivo, no VDBP cleavage was found in kidneys or liver from legumain-deficient mice (Lgmn-/-), whereas VDBP was cleaved in wild-type control mice (Lgmn+/+). Finally, legumain deficiency resulted in increased plasma levels of 25(OH)D3 and total VD3 and altered expression of key renal enzymes involved in VD3 metabolism (CYP24A1 and CYP27B1). In conclusion, a regulatory interplay between VD3 and legumain is suggested.
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Affiliation(s)
- Karl Martin Forbord
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway; (K.M.F.)
- Department of Endocrinology and Metabolism, Odense University Hospital, University of Southern Denmark, 5230 Odense, Denmark
| | - Meshail Okla
- Department of Endocrinology and Metabolism, Odense University Hospital, University of Southern Denmark, 5230 Odense, Denmark
- Department of Community Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh 11433, Saudi Arabia
| | - Ngoc Nguyen Lunde
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway; (K.M.F.)
| | - Tatjana Bosnjak-Olsen
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway; (K.M.F.)
| | - Guro Arnekleiv
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway; (K.M.F.)
| | - Daniel Hesselson
- Centenary Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia
| | - Harald Thidemann Johansen
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway; (K.M.F.)
| | - Jonathan C. Y. Tang
- Bioanalytical Facility, Norwich Medical School, University of East Anglia, Norwich NR4 7TJ, UK;
- Clinical Biochemistry, Norfolk and Norwich University Hospital, Norwich NR4 7UY, UK
| | - Moustapha Kassem
- Department of Endocrinology and Metabolism, Odense University Hospital, University of Southern Denmark, 5230 Odense, Denmark
- Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Rigmor Solberg
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway; (K.M.F.)
| | - Abbas Jafari
- Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
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Norlin M, Wikvall K. Enzymatic activation in vitamin D signaling - Past, present and future. Arch Biochem Biophys 2023; 742:109639. [PMID: 37196753 DOI: 10.1016/j.abb.2023.109639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 05/10/2023] [Accepted: 05/14/2023] [Indexed: 05/19/2023]
Abstract
Vitamin D signaling is important in regulating calcium homeostasis essential for bone health but also displays other functions in cells of several tissues. Disturbed vitamin D signaling is linked to a large number of diseases. The multiple cytochrome P450 (CYP) enzymes catalyzing the different hydroxylations in bioactivation of vitamin D3 are crucial for vitamin D signaling and function. This review is focused on the progress achieved in identification of the bioactivating enzymes and their genes in production of 1α,25-dihydroxyvitamin D3 and other active metabolites. Results obtained on species- and tissue-specific expression, catalytic reactions, substrate specificity, enzyme kinetics, and consequences of gene mutations are evaluated. Matters of incomplete understanding regarding the physiological roles of some vitamin D hydroxylases are critically discussed and the authors will give their view of the importance of each enzyme for vitamin D signaling. Roles of different vitamin D receptors and an alternative bioactivation pathway, leading to 20-hydroxylated vitamin D3 metabolites, are also discussed. Considerable progress has been achieved in knowledge of the vitamin D3 bioactivating enzymes. Nevertheless, several intriguing areas deserve further attention to understand the pleiotropic and diverse activities elicited by vitamin D signaling and the mechanisms of enzymatic activation necessary for vitamin D-induced responses.
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Affiliation(s)
- Maria Norlin
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.
| | - Kjell Wikvall
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
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Cao Y, Shu XB, Yao Z, Ji G, Zhang L. Is vitamin D receptor a druggable target for non-alcoholic steatohepatitis? World J Gastroenterol 2020; 26:5812-5821. [PMID: 33132636 PMCID: PMC7579753 DOI: 10.3748/wjg.v26.i38.5812] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 08/28/2020] [Accepted: 09/08/2020] [Indexed: 02/06/2023] Open
Abstract
Nonalcoholic steatohepatitis (NASH) is a progressed stage of non-alcoholic fatty liver disease, and available therapeutic strategies for NASH are limited. Vitamin D receptor (VDR) is proposed as a druggable target for NASH due to the discovery of vitamin D deficiency in NASH patients. To date, vitamin D supplementation has not consistently conferred expected therapeutic benefits, raising the question of whether VDR can serve as a proper drug target for NASH. It is known that VDR can interact with other ligands such as bile acids in addition to vitamin D, and its expression can be induced by fatty acids, and insulin. It has also been shown that while activation of VDR in hepatic macrophages and hepatic stellate cells resulted in attenuation of hepatic inflammation and fibrosis, activation of VDR in hepatocytes could accelerate lipid accumulation. Thus, the multiplicity of VDR ligands, together with the cell type-specificity of VDR activation, must be taken into consideration in assessing the validity of VDR being a potential druggable target for NASH treatment. To this end, we have evaluated the relationship between VDR activation and various contributing factors, such as gut microbiota, bile acid, fatty acids, and insulin, in addition to vitamin D, with an expectation that a potential drug might be identified that can elicit VDR activation in a tissue- and/or cell type-specific manner and therefore achieving therapeutic benefits in NASH.
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Affiliation(s)
- Ying Cao
- Institute of Digestive Diseases, Longhua Hospital, China-Canada Center of Research for Digestive Diseases, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, China
| | - Xiang-Bing Shu
- Institute of Digestive Diseases, Longhua Hospital, China-Canada Center of Research for Digestive Diseases, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, China
- Department of Geratology, Baoshan Branch of Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 201999, China
| | - Zemin Yao
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa K1H8M5, Ontario, Canada
| | - Guang Ji
- Institute of Digestive Diseases, Longhua Hospital, China-Canada Center of Research for Digestive Diseases, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, China
| | - Li Zhang
- Institute of Digestive Diseases, Longhua Hospital, China-Canada Center of Research for Digestive Diseases, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, China
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Bikle DD, Patzek S, Wang Y. Physiologic and pathophysiologic roles of extra renal CYP27b1: Case report and review. Bone Rep 2018; 8:255-267. [PMID: 29963603 PMCID: PMC6021194 DOI: 10.1016/j.bonr.2018.02.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/06/2018] [Accepted: 02/23/2018] [Indexed: 01/13/2023] Open
Abstract
Although the kidney was initially thought to be the sole organ responsible for the production of 1,25(OH)2D via the enzyme CYP27b1, it is now appreciated that the expression of CYP27b1 in tissues other than the kidney is wide spread. However, the kidney is the major source for circulating 1,25(OH)2D. Only in certain granulomatous diseases such as sarcoidosis does the extra renal tissue produce sufficient 1,25(OH)2D to contribute to the circulating levels, generally associated with hypercalcemia, as illustrated by the case report preceding the review. Therefore the expression of CYP27b1 outside the kidney under normal circumstances begs the question why, and in particular whether the extra renal production of 1,25(OH)2D has physiologic importance. In this chapter this question will be discussed. First we discuss the sites for extra renal 1,25(OH)2D production. This is followed by a discussion of the regulation of CYP27b1 expression and activity in extra renal tissues, pointing out that such regulation is tissue specific and different from that of CYP27b1 in the kidney. Finally the physiologic significance of extra renal 1,25(OH)2D3 production is examined, with special focus on the role of CYP27b1 in regulation of cellular proliferation and differentiation, hormone secretion, and immune function. At this point the data do not clearly demonstrate an essential role for CYP27b1 expression in any tissue outside the kidney, but several examples pointing in this direction are provided. With the availability of the mouse enabling tissue specific deletion of CYP27b1, the role of extra renal CYP27b1 expression in normal and pathologic states can now be addressed definitively.
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Affiliation(s)
- Daniel D Bikle
- Department of Medicine, Endocrine Research Unit, Veterans Affairs Medical Center, University of California San Francisco, United States
| | - Sophie Patzek
- Department of Medicine, Endocrine Research Unit, Veterans Affairs Medical Center, University of California San Francisco, United States
| | - Yongmei Wang
- Department of Medicine, Endocrine Research Unit, Veterans Affairs Medical Center, University of California San Francisco, United States
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Satué M, Córdoba A, Ramis JM, Monjo M. UV-irradiated 7-dehydrocholesterol coating on polystyrene surfaces is converted to active vitamin D by osteoblastic MC3T3-E1 cells. Photochem Photobiol Sci 2013; 12:1025-35. [PMID: 23538933 DOI: 10.1039/c3pp50025j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The aim of the present study was to determine the effects of UV irradiation on the conversion of 7-dehydrocholesterol (7-DHC), which has been coated onto a polystyrene surface, to cholecalciferol (D3), and the resulting effect on the formation of vitamin D (1,25-D3) by MC3T3-E1 cells. The changes in gene expression of the enzymes regulating its hydroxylation, Cyp27b1 and Cyp27a1, were monitored as well as the net effect of the UV-treated 7-DHC coating on cell viability and osteoblast differentiation. MC3T3-E1 cells were found to express the enzymes required for synthesizing active 1,25-D3, and we found a dose-dependent increase in the production of both 25-D3 and 1,25-D3 levels for UV-activated 7-DHC samples unlike UV-untreated ones. Cell viability revealed no cytotoxic effect for any of the treatments, but only for the highest dose of 7-DHC (20 nmol per well) that was UV-irradiated. Furthermore, osteoblast differentiation was increased in cells treated with some of the higher doses of 7-DHC when UV-irradiated, as shown by collagen-I, osterix and osteocalcin relative mRNA levels. The conversion of 7-DHC to preD3 exogenously by UV irradiation and later to 25-D3 by MC3T3-E1 cells was determined for the optimum 7-DHC dose (0.2 nmol per well), i.e. 8.6 ± 0.7% of UV-activated 7-DHC was converted to preD3 and 6.7 ± 2.8% of preD3 was finally converted to 25-D3 under the conditions studied. In conclusion, we demonstrate that an exogenous coating of 7-DHC, when UV-irradiated, can be used to endogenously produce active vitamin D. We hereby provide the scientific basis for UV-activated 7-DHC coating as a feasible approach for implant therapeutics focused on bone regeneration.
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Affiliation(s)
- María Satué
- Department of Fundamental Biology and Health Sciences, Research Institute on Health Sciences (IUNICS), University of Balearic Islands, Spain
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UV photoactivation of 7-dehydrocholesterol on titanium implants enhances osteoblast differentiation and decreases Rankl gene expression. Acta Biomater 2013. [PMID: 23201015 DOI: 10.1016/j.actbio.2012.11.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Vitamin D plays a central role in bone regeneration, and its insufficiency has been reported to have profound negative effects on implant osseointegration. The present study aimed to test the in vitro biological effect of titanium (Ti) implants coated with UV-activated 7-dehydrocholesterol (7-DHC), the precursor of vitamin D, on cytotoxicity and osteoblast differentiation. Fourier transform infrared spectroscopy confirmed the changes in chemical structure of 7-DHC after UV exposure. High-pressure liquid chromatography analysis determined a 16.5±0.9% conversion of 7-DHC to previtamin D(3) after 15min of UV exposure, and a 34.2±4.8% of the preD(3) produced was finally converted to 25-hydroxyvitamin D(3) (25-D(3)) by the osteoblastic cells. No cytotoxic effect was found for Ti implants treated with 7-DHC and UV-irradiated. Moreover, Ti implants treated with 7-DHC and UV-irradiated for 15min showed increased 25-D(3) production, together with increased ALP activity and calcium content. Interestingly, Rankl gene expression was significantly reduced in osteoblasts cultured on 7-DHC-coated Ti surfaces when UV-irradiated for 15 and 30min to 33.56±15.28% and 28.21±4.40%, respectively, compared with the control. In conclusion, these findings demonstrate that UV-activated 7-DHC is a biocompatible coating of Ti implants, which allows the osteoblastic cells to produce themselves active vitamin D, with demonstrated positive effects on osteoblast differentiation in vitro.
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7
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Tang EKY, Tieu EW, Tuckey RC. Expression of human CYP27B1 inEscherichia coliand characterization in phospholipid vesicles. FEBS J 2012; 279:3749-3761. [DOI: 10.1111/j.1742-4658.2012.08736.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Abstract
The concept of a circulating RAS is well established and known to play an endocrine role in the regulation of fluid homeostasis (see Section 4.1, Chapter 4). However, it is more appropriate to view the RAS in the contemporary notion as an “angiotensin-generating system”, which consists of angiotensinogen, angiotensin-generating enzymes, and angiotensins, as well as their receptors. Some RASs can be termed as “complete”, having renin and ACE involved in the biosynthesis of angiotensin II peptide, i.e. in a renin and/or ACE-dependent manner which is exemplified in the circulating RAS. On the other hand, some RAS can be termed as “partial”, having alternate enzymes to renin and ACE, such as chymase and ACE2 (see Section 4.3, Chapter 4) available for the generation of angiotensin II and other bioactive angiotensin peptides in the biosynthetic cascade, i.e. in a renin and/or ACE-independent manner. Complete vs. partial RASs can be exemplified in the so-called intrinsic angiotensin-generating system or local RAS; for example, a local and functional RAS with renin and ACE-dependent but a renin-independent pathway have been indentified in the pancreas and carotid body, respectively. In the past two decades, local RASs have gained increasing recognition especially with regards to their clinical importance. Distinct from the circulating RAS, these functional local RASs exist in such diverse tissues and organs as the pancreas, liver, intestine, heart, kidney, vasculature, carotid body, and adipose, as well as the nervous, reproductive, and digestive systems. Taken into previous findings from our laboratory and others together, Table 5.1 is a summary of some recently identified local RASs in various levels of tissues and organs.
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Affiliation(s)
- Po Sing Leung
- School of Biomedical Sciences Faculty of Medicine The Chinese University of Hong Kong, Shatin Hong Kong, China
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10
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The skeleton as an intracrine organ for vitamin D metabolism. Mol Aspects Med 2008; 29:397-406. [PMID: 18602685 DOI: 10.1016/j.mam.2008.05.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Accepted: 05/15/2008] [Indexed: 11/23/2022]
Abstract
The endocrine hormone, 1alpha,25-dihydroxyvitamin D(3) (1,25D) is an important regulator of calcium and phosphorus homeostasis. In this context, 1,25D is generally recognized as necessary for the maintenance of a healthy skeleton through its actions on the small intestine. In this review, we highlight the direct effects of 1,25D on the constituent cells of the bone, actions that are independent of effects on the intestine and kidney. We also consider the evidence that 25D levels, not 1,25D levels, correlate best with parameters of bone health, and that the bone itself is a site of metabolic conversion of 25D into 1,25D, by virtue of its expression of the 25-hydroxyvitamin D 1alpha-hydroxylase, CYP27B1. We review the evidence that at least osteoblasts and chondrocytes, and possibly also bone resorbing osteoclasts, are capable of such metabolic conversion, and therefore that these cells likely participate in autocrine and paracrine loops of vitamin D metabolism. We conclude that the skeleton is an intracrine organ for vitamin D metabolism, challenging the long-held notion that 1,25D is solely an endocrine hormone.
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Atkins GJ, Anderson PH, Findlay DM, Welldon KJ, Vincent C, Zannettino ACW, O'Loughlin PD, Morris HA. Metabolism of vitamin D3 in human osteoblasts: evidence for autocrine and paracrine activities of 1 alpha,25-dihydroxyvitamin D3. Bone 2007; 40:1517-28. [PMID: 17395559 DOI: 10.1016/j.bone.2007.02.024] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Revised: 01/31/2007] [Accepted: 02/21/2007] [Indexed: 11/19/2022]
Abstract
Circulating 1 alpha,25-dihydroxyvitamin D(3) (1,25D) derives from renal conversion of 25-hydroxyvitamin D(3) (25D), by the 25D 1 alpha-hydroxylase (CYP27B1). Blood 25D levels, but not 1,25D levels, are the best indicator of vitamin D status and predict fracture risk in the elderly. We examined the extent to which osteoblasts can metabolize 25D. Well-characterized human primary osteoblasts and osteosarcoma (OS) cell lines were examined for the expression and regulation of genes associated with vitamin D metabolism, using real-time PCR. Primary osteoblasts and OS cell lines were found to express CYP27B1 mRNA and secreted detectable 1,25D in response to 25D. Of the OS cell lines tested, HOS expressed the most CYP27B1 mRNA and secreted the highest levels of 1,25D. All osteoblastic cells examined up-regulated expression of the catabolic regulator of 1,25D, the 25-hydroxyvitamin D-24-hydroxylase (CYP24), when incubated with either 1,25D or 25D. Exposure to physiological levels of 25D resulted in up-regulated transcription of the 1,25D responsive genes, osteocalcin (OCN), osteopontin (OPN) and RANKL. Specific knockdown of CYP27B1 in HOS cells using siRNA resulted in up to 80% reduction in both 1,25D secretion and the transcription of OCN and CYP24, strongly implying that the 25D effect in osteoblasts is preceded by conversion to 1,25D. Incubation with 25D, like 1,25D, inhibited primary osteoblast proliferation and promoted in vitro mineralization. Finally, we detected expression by osteoblasts of receptors for vitamin D binding protein (DBP), cubilin and megalin, suggesting that osteoblasts are able to internalize DBP-25D complexes in vivo. Together, our results suggest that autocrine, and perhaps paracrine, pathways of vitamin D(3) metabolism may regulate key osteoblast functions independently of circulating, kidney derived 1,25D. Our results are therefore consistent with the reported benefits of maintaining a healthy vitamin D status in the elderly to reduce the risk of fractures.
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Affiliation(s)
- Gerald J Atkins
- Department of Orthopaedics and Trauma, University of Adelaide, Adelaide, South Australia 5000, Australia.
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Kinbara K, Aida T. Toward intelligent molecular machines: directed motions of biological and artificial molecules and assemblies. Chem Rev 2005; 105:1377-400. [PMID: 15826015 DOI: 10.1021/cr030071r] [Citation(s) in RCA: 673] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kazushi Kinbara
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Thordarson P, Bijsterveld EJA, Rowan AE, Nolte RJM. Epoxidation of polybutadiene by a topologically linked catalyst. Nature 2003; 424:915-8. [PMID: 12931181 DOI: 10.1038/nature01925] [Citation(s) in RCA: 325] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2003] [Accepted: 07/17/2003] [Indexed: 01/16/2023]
Abstract
Nature has evolved complex enzyme architectures that facilitate the synthesis and manipulation of the biopolymers DNA and RNA, including enzymes capable of attaching to the biopolymer substrate and performing several rounds of catalysis before dissociating. Many of these 'processive' enzymes have a toroidal shape and completely enclose the biopolymer while moving along its chain, as exemplified by the DNA enzymes T4 DNA polymerase holoenzyme and lambda-exonucleoase. The overall architecture of these systems resembles that of rotaxanes, in which a long molecule or polymer is threaded through a macrocycle. Here we describe a rotaxane that mimics the ability of processive enzymes to catalyse multiple rounds of reaction while the polymer substrate stays bound. The catalyst consists of a substrate binding cavity incorporating a manganese(III) porphyrin complex that oxidizes alkenes within the toroid cavity, provided a ligand has been attached to the outer face of the toroid to both activate the porphyrin complex and shield it from being able to oxidize alkenes outside the cavity. We find that when threaded onto a polybutadiene polymer strand, this catalyst epoxidizes the double bonds of the polymer, thereby acting as a simple analogue of the enzyme systems.
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Affiliation(s)
- Pall Thordarson
- Department of Organic Chemistry, NSRIM, University of Nijmegen, Toernooiveld 1, 6525 ED, Nijmegen, The Netherlands
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Henry HL. Vitamin D. Compr Physiol 2000. [DOI: 10.1002/cphy.cp070318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Sakaki T, Sawada N, Takeyama K, Kato S, Inouye K. Enzymatic properties of mouse 25-hydroxyvitamin D3 1 alpha-hydroxylase expressed in Escherichia coli. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 259:731-8. [PMID: 10092858 DOI: 10.1046/j.1432-1327.1999.00096.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Renal 25-hydroxyvitamin D3 1 alpha-hydroxylase cDNA cloned from the kidneys of mice lacking the vitamin D receptor was expressed in Escherichia coli JM109. As expected, the bacterially-expressed enzyme catalyzes the 1 alpha-hydroxylation of 25-hydroxyvitamin D3 with a Michaelis constant, K(m), value of 2.7 microM. Unexpectedly, the enzyme also hydroxylates the 1 alpha-position of 24,25-dihydroxyvitamin D3 with a K(m) of 1.3 microM, and a fourfold higher Vmax/K(m) compared with the 25-hydroxyvitamin D3 hydroxylase activity, suggesting that 24,25-dihydroxyvitamin D3 is a better substrate than 25-hydroxyvitamin D3 for 1 alpha-hydroxylase. In addition, the enzyme showed 1 alpha-hydroxylase activity toward 24-oxo-25-hydroxyvitamin D3. However, it showed only slight activity towards 23,25-dihydroxyvitamin D3 and 24-oxo-23,25-dihydroxyvitamin D3, and no detectable activity towards vitamin D3 and 24,25,26,27-tetranor-23-hydroxyvitamin D3. These results suggest that the 25-hydroxyl group of vitamin D3 is essential for the 1 alpha-hydroxylase activity and the 24-hydroxyl group enhances the activity, but the 23-hydroxyl group greatly reduced the activity. Another remarkable finding is that living recombinant E. coli cells can convert the substrates into the 1 alpha-hydroxylated products, suggesting the presence of a redox partner of 1 alpha-hydroxylase in E. coli cells.
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Affiliation(s)
- T Sakaki
- Division of Applied Life Sciences, Kyoto University, Japan
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Axén E, Harmeyer J, Wikvall K. Renal and hepatic 1 alpha-hydroxylation of 25-hydroxyvitamin D3 in piglets suffering from pseudo vitamin D-deficiency rickets, type I. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1407:234-42. [PMID: 9748599 DOI: 10.1016/s0925-4439(98)00047-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The piglets examined suffer from rickets and have symptoms similar to those of classic pseudo vitamin D-deficiency rickets, type I (PVDRI), including plasma concentrations of 1 alpha, 25-dihydroxyvitamin D3 considerably lower than in healthy control piglets. It has been suggested that the rachitic piglets have a defective renal 1 alpha,25-dihydroxyvitamin D3 production. The present study shows that partially purified mitochondrial and microsomal cytochrome P450 from kidney and liver of both rachitic and control animals is able to catalyze 1 alpha-hydroxylation of 25-hydroxyvitamin D3. The renal mitochondrial 1 alpha-hydroxylase activity was higher in the rachitic piglets whereas the renal microsomal 1 alpha-hydroxylase activity was decreased. The immunodetectable levels in kidney of a mitochondrial 1 alpha-hydroxylase (CYP27) and a microsomal 1 alpha-hydroxylase (vitamin D3 25-hydroxylase) were correlated with the 1 alpha-hydroxylase activities. The results suggest that the renal microsomal 1 alpha-hydroxylase is affected by the rachitic condition. It is concluded that the primary genetic defect of systemic 1 alpha,25-dihydroxyvitamin D3 deficiency in the rachitic PVDRI piglets does not reside in a defective function or absence of renal mitochondrial 25-hydroxyvitamin D3 1 alpha-hydroxylase. From this, it may also be concluded that PVDRI in man and pig appear to be two different forms of the disease.
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Affiliation(s)
- E Axén
- Department of Pharmaceutical Biosciences, University of Uppsala, Sweden
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Kimmel PL, Phillips TM, Lew SQ, Langman CB. Zinc modulates mononuclear cellular calcitriol metabolism in peritoneal dialysis patients. Kidney Int 1996; 49:1407-12. [PMID: 8731107 DOI: 10.1038/ki.1996.198] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Zinc has long been known to play a role in maintaining immunologic function. Hypozincemia, however, is common in patients with end-stage renal disease (ESRD) treated with continuous ambulatory peritoneal dialysis (CAPD). We previously demonstrated that zinc depletion limits the ability of animals to achieve maximum circulating calcitriol levels in response to the stress of calcium or phosphorus depletion. It was unclear, however, whether changes in the circulating levels of calcitriol in these settings was associated with a direct effect on renal 1-alpha hydroxylase activity, or whether the zinc dependence of the stimulated calcitriol response involved an integrated systemic response in intact animals. In addition it was unclear whether circulating zinc levels or zinc nutritional status modified calcitriol metabolism in humans. To better understand the role zinc plays in the immune response in patients with ESRD, we studied IL-1, calcitriol and tumor necrosis factor-alpha production by mononuclear cells from blood and peritoneal effluents of 22 patients with ESRD treated with CAPD. Macrophages from peritoneal effluents and peripheral blood mononuclear cells were isolated and pulsed with phytohemagglutinin in medium to which different concentrations of zinc chloride, copper chloride, and carbonyl cyanide p-(trifluoromethoxy)-phenyl-hydrazone (FCCP), an inhibitor of mitochondrial function were added. Supernatant interleukin-1, calcitriol, and tumor necrosis factor-alpha levels were subsequently measured. We demonstrated a zinc concentration dependent increase in stimulated IL-1 alpha and -beta, and TNF-alpha release in both peripheral mononuclear cells and peritoneal macrophages from patients with ESRD treated with CAPD. The effect is zinc specific, as it is not reproduced by copper or chloride supplementation. A zinc concentration dependent increase in peritoneal macrophage calcitriol release was also noted. FCCP blocked the cellular production of IL-1 alpha, IL-1 beta, and TNF-alpha, but had little effect on zinc-induced stimulated mononuclear cell supernatant calcitriol levels. The different shape of the zinc dose response curve, and the lack of correlation between paired IL-1 and calcitriol supernatant levels suggests the effect of zinc on mononuclear cellular cytokine and calcitriol production is mediated through different pathways.
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Affiliation(s)
- P L Kimmel
- Rita Gusack Laboratory, Department of Medicine, George Washington University Medical Center, Washington, D.C., USA
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Sardar S, Chatterjee M, Ghosh S, Roy K. Role of vitamin D3 on the activity patterns of hepatic drug metabolizing enzymes in transplantable murine lymphoma. Cancer Invest 1996; 14:328-34. [PMID: 8689427 DOI: 10.3109/07357909609012159] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Vitamin D3 (D3) has been found to exert varied pharmacological actions including restriction of cell growth of a number of malignant cell lines in vitro and inhibition of the promotion of chemical carcinogenesis in mouse skin. In an attempt to confirm the efficacy of D3 as an antineoplastic agent, the present investigation aims at characterizing the importance of D3 in modulating hepatic drug metabolizing enzymes, namely, cytosolic glutathione S-transferase (GSHT), microsomal UDP glucuronyl transferase (UDPGT), and cytochrome P-450, which have been reported by us in recent literature as significant neoplastic markers in mice bearing Dalton's lymphoma (DL). Results show that D3 causes a 150% elevation of GSHT activity and the maintenance of normal, near-control UDPGT activity and cytochrome P-450 content, up to almost 30 days following tumor transplantation, along with bringing about a twofold increase in survival of the host mice. In conclusion, we confirm the definite and significant antitumorigenic role of D3 and its involvement with the discussed hepatic tumor markers in monitoring the processes that lead to cell survival.
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Affiliation(s)
- S Sardar
- Division of Biochemistry, Department of Pharmaceutical Technology, Jadavpur University, Calcutta, India
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Allegretto EA, Shevde N, Zou A, Howell SR, Boehm MF, Hollis BW, Pike JW. Retinoid X receptor acts as a hormone receptor in vivo to induce a key metabolic enzyme for 1,25-dihydroxyvitamin D3. J Biol Chem 1995; 270:23906-9. [PMID: 7592579 DOI: 10.1074/jbc.270.41.23906] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We demonstrate here that RNA levels of 25-hydroxy-vitamin D3-24-hydroxylase (24-(OH)ase), a key catabolic enzyme for 1,25-dihydroxyvitamin D3, are increased by a highly selective retinoid X receptor (RXR) ligand, LG100268, in mice within hours. Correspondingly, upon LG100268 treatment, kidney 24-(OH)ase enzymatic activity increases 5-10-fold. The endogenous retinoid hormones, all-trans-retinoic acid and 9-cis-retinoic acid, and the synthetic retinoic acid receptor-selective compound, TTNPB, also stimulate 24-(OH)ase. Additionally, we show that LG100268 stimulates transcription of a luciferase reporter plasmid driven by 24-(OH)ase promoter sequences in the presence of RXR in CV-1 cell cotransactivation assays. This first demonstration of a gene that is regulated in the intact animal through an RXR-mediated pathway confirms earlier hypotheses that RXR is a bona fide hormone receptor. Regulation of a key gene in the vitamin D signaling pathway by a retinoid transducer may provide a molecular basis for some of the documented biological effects of vitamin A on bone and vitamin D metabolism.
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Affiliation(s)
- E A Allegretto
- Department of Biochemistry, Ligand Pharmaceuticals, San Diego, California 92121, USA
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Axén E, Postlind H, Sjöberg H, Wikvall K. Liver mitochondrial cytochrome P450 CYP27 and recombinant-expressed human CYP27 catalyze 1 alpha-hydroxylation of 25-hydroxyvitamin D3. Proc Natl Acad Sci U S A 1994; 91:10014-8. [PMID: 7937829 PMCID: PMC44948 DOI: 10.1073/pnas.91.21.10014] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
A cytochrome P450 catalyzing 1 alpha-hydroxylation of 25-hydroxyvitamin D3 was purified from pig liver mitochondria. It also catalyzed 27-hydroxylation of 25-hydroxyvitamin D3 and 25-hydroxylation of vitamin D3. The ratio between the 1 alpha-, 27-, and 25-hydroxylase activities remained essentially constant during the purification. Substrates for sterol 27-hydroxylase CYP27 inhibited and a monoclonal antibody raised against CYP27 immunoprecipitated the 1 alpha-, 27-, and 25-hydroxylase activities. Apparently homogeneous preparations of CYP27 from pig and rabbit liver mitochondria catalyzed 1 alpha-hydroxylation. Human liver mitochondrial CYP27 was expressed from its cDNA in Escherichia coli. The nucleotide sequence encoding the N terminus of CYP27 was modified in the first eight codons to achieve expression in E. coli. The purified recombinant-expressed CYP27 reconstituted with the electron-transferring system of adrenal mitochondria catalyzed 1 alpha-hydroxylation of 25-hydroxyvitamin D3. Expression of unmodified CYP27 cDNA in simian COS cells confirmed the 1 alpha-hydroxylase activity toward 25-hydroxyvitamin D3.
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Affiliation(s)
- E Axén
- Department of Pharmaceutical Biosciences, University of Uppsala, Sweden
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22
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Ferryl iron and protein free radicals. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/s0167-7306(08)60439-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Negrea L, Slatopolsky E, Dusso A. Lower affinity for substrate for extrarenal synthesis of calcitriol in chronic uremia. Kidney Int 1993; 44:134-8. [PMID: 8355454 DOI: 10.1038/ki.1993.223] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Previous studies from our laboratory have shown that anephric patients have very low, but detectable, levels of 1,25(OH)2D3 (calcitriol) that can be increased to normal by administration of large doses of 25(OH)D3. The report of 1 alpha-hydroxylase activity in pig liver with an affinity for substrate significantly lower than that of the renal enzyme, led us to use the rat as an experimental model to further clarify the need of supraphysiological levels of 25(OH)D3 to correct calcitriol deficiency in chronic uremia. We have measured 1,25(OH)2D3 production by rat liver. Cytosol free liver homogenates (CFH) from normal rats were incubated with 25(OH)D3 and the production of 1,25(OH)2D3 was measured using the thymus radioreceptor assay after solid phase C18 extraction and HPLC purification of the samples. 1,25(OH)2D3 production was linear up to 30 minutes and a CFH protein concentration up to 20 mg. Saturability was attained for a substrate concentration of approximately 60 microM. Ketoconazole, a cytochrome P450 inhibitor, blocked calcitriol production in a dose dependent fashion. Total inhibition of the liver 1 alpha-hydroxylase was achieved with 180 microM ketoconazole. We next compared the kinetics of the 1 alpha-hydroxylases of normal and uremic rat livers. Maximal velocities were not statistically different (139.6 +/- 22.3 pg/mg/min for normals and 217.1 +/- 73.3 pg/mg/min for uremic rats). However, the apparent Km was 35.9 +/- 3.2 microM for uremic animals, significantly higher (P < or = 0.001) than that of normal rats (16.6 +/- 0.7 microM).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L Negrea
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
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Hagenfeldt Y, Berlin T. The human renal 25-hydroxyvitamin D3-1 alpha-hydroxylase: properties studied by isotope-dilution mass spectrometry. Eur J Clin Invest 1992; 22:223-8. [PMID: 1499638 DOI: 10.1111/j.1365-2362.1992.tb01455.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The renal 25-hydroxyvitamin D3-1 alpha-hydroxylase activity has been measured in normal human kidney cortex, using a highly specific assay based on isotope-dilution mass spectrometry. The cortex was obtained from kidneys removed due to renal tumours. The subcellular distribution of 25-hydroxyvitamin D3-1 alpha-hydroxylase activity was studied. Enzyme activity was only observed in the mitochondrial fraction. Mitochondria from non-tumourous kidney cortex had a Vmax of 0.17 +/- 0.02 pmol min-1 mg-1 protein and the apparent Km was in the range of 14 mumol l-1. There was a tendency to a higher 25-hydroxyvitamin D3-1 alpha-hydroxylase activity in preparations from male kidney (0.21 +/- 0.03 pmol min-1 mg-1 protein) than female (0.12 +/- 0.02, P less than 0.05). A significant inverse correlation between serum phosphate and 25-hydroxyvitamin D3-1 alpha-hydroxylase activity was found. No correlation was observed between enzyme activity and serum levels of 1,25-dihydroxyvitamin D (total and free index), PTH, total calcium or ionized calcium. The results indicate that there is a sex difference in human 25-hydroxyvitamin D3-1 alpha-hydroxylase activity similar to the one observed in laboratory animals. Furthermore, the data support the hypothesis that serum phosphate is a major regulator of 1,25-dihydroxyvitamin D3 production in man.
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Affiliation(s)
- Y Hagenfeldt
- Department of Clinical Chemistry, Karolinska Institute, Huddinge University Hospital, Sweden
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Posch KC, Boerman MH, Burns RD, Napoli JL. Holocellular retinol binding protein as a substrate for microsomal retinal synthesis. Biochemistry 1991; 30:6224-30. [PMID: 2059629 DOI: 10.1021/bi00239a021] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Holocellular retinol binding protein (holo-CRBP) was substrate for retinal synthesis at physiological pH with microsomes prepared from rat liver, kidney, lung, and testes. Four observations indicated that retinal synthesis was supported by holo-CRBP directly, rather than by the unbound retinol in equilibrium with CRBP. First, the rate of retinal synthesis with holo-CRBP exceeded the rate that was observed from the concentration of unbound retinol in equilibrium with CRBP. Second, NADP was the preferred cofactor only with holo-CRBP, supporting a rate about 3-fold greater than that of NAD. In contrast, with unbound retinol as substrate, similar rates of retinal formation were supported by either NAD or NADP. Third, the rate of retinal synthesis was not related to the decrease in the concentration of unbound retinol in equilibrium with holo-CRBP caused by increasing the concentration of apo-CRBP. Fourth, the rate of retinal synthesis increased with increases in the concentration of holo-CRBP as a fixed concentration of unbound retinol was maintained. This was achieved by increasing both apo-CRBP and holo-CRBP, but keeping constant the ratio apo-CRBP/holo-CRBP. Retinal formation from holo-CRBP displayed typical Michaelis-Menten kinetics with a Km about 1.6 microM, less than the physiological retinal concentration of 4-10 microM in the livers of rats fed diets with recommended vitamin A levels. The Vmax for retinal formation from holo-CRBP was 14-17 pmol min-1 (mg of protein)-1, a rate sufficiently high to generate adequate retinal to contribute significantly to retinoic acid synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K C Posch
- Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York, Buffalo 14214
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