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Hong K, Yu M, Crowther J, Mei L, Olsen K, Luo Y, Chen YE, Guo Y, Schwendeman A. Effect of Lipid Composition on the Atheroprotective Properties of HDL-Mimicking Micelles. Pharmaceutics 2022; 14:pharmaceutics14081570. [PMID: 36015196 PMCID: PMC9415476 DOI: 10.3390/pharmaceutics14081570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/22/2022] [Accepted: 07/24/2022] [Indexed: 02/01/2023] Open
Abstract
Atherosclerosis progression is driven by an imbalance of cholesterol and unresolved local inflammation in the arteries. The administration of recombinant apolipoprotein A-I (ApoA-I)-based high-density lipoprotein (HDL) nanoparticles has been used to reduce the size of atheroma and rescue inflammatory response in clinical studies. Because of the difficulty in producing large quantities of recombinant ApoA-I, here, we describe the preparation of phospholipid-based, ApoA-I-free micelles that structurally and functionally resemble HDL nanoparticles. Micelles were prepared using various phosphatidylcholine (PC) lipids combined with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[azido(polyethylene glycol)-2000] (DSPE-PEG2k) to form nanoparticles of 15-30 nm in diameter. The impacts of PC composition and PEGylation on the anti-inflammatory activity, cholesterol efflux capacity, and cholesterol crystal dissolution potential of micelles were investigated in vitro. The effects of micelle composition on pharmacokinetics and cholesterol mobilization ability were evaluated in vivo in Sprague Dawley rats. The study shows that the composition of HDL-mimicking micelles impacts their overall atheroprotective properties and supports further investigation of micelles as a therapeutic for the treatment of atherosclerosis.
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Affiliation(s)
- Kristen Hong
- Department of Pharmaceutical Sciences and the Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA; (K.H.); (M.Y.); (J.C.); (L.M.); (K.O.)
| | - Minzhi Yu
- Department of Pharmaceutical Sciences and the Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA; (K.H.); (M.Y.); (J.C.); (L.M.); (K.O.)
| | - Julia Crowther
- Department of Pharmaceutical Sciences and the Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA; (K.H.); (M.Y.); (J.C.); (L.M.); (K.O.)
| | - Ling Mei
- Department of Pharmaceutical Sciences and the Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA; (K.H.); (M.Y.); (J.C.); (L.M.); (K.O.)
| | - Karl Olsen
- Department of Pharmaceutical Sciences and the Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA; (K.H.); (M.Y.); (J.C.); (L.M.); (K.O.)
| | - Yonghong Luo
- Department of Internal Medicine, Frankel Cardiovascular Center, University of Michigan, Ann Arbor, MI 48109, USA; (Y.L.); (Y.E.C.)
| | - Yuqing Eugene Chen
- Department of Internal Medicine, Frankel Cardiovascular Center, University of Michigan, Ann Arbor, MI 48109, USA; (Y.L.); (Y.E.C.)
| | - Yanhong Guo
- Department of Internal Medicine, Frankel Cardiovascular Center, University of Michigan, Ann Arbor, MI 48109, USA; (Y.L.); (Y.E.C.)
- Correspondence: (Y.G.); (A.S.)
| | - Anna Schwendeman
- Department of Pharmaceutical Sciences and the Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA; (K.H.); (M.Y.); (J.C.); (L.M.); (K.O.)
- Correspondence: (Y.G.); (A.S.)
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2
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Lipoproteins for therapeutic delivery: recent advances and future opportunities. Ther Deliv 2018; 9:257-268. [DOI: 10.4155/tde-2017-0122] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The physiological role(s) of mammalian plasma lipoproteins is to transport hydrophobic molecules (primarily cholesterol and triacylglycerols) to their respective destinations. Lipoproteins have also been studied as drug-delivery agents due to their advantageous payload capacity, long residence time in the circulation and biocompatibility. The purpose of this review is to briefly discuss current findings with the focus on each type of formulation's potential for clinical applications. Regarding utilizing lipoprotein type formulation for cancer therapeutics, their potential for tumor-selective delivery is also discussed.
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3
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Efficient purification of Apolipoprotein A1 (ApoA1) from plasma by HEA HyperCel™: An alternative approach. J Chromatogr B Analyt Technol Biomed Life Sci 2018; 1073:104-109. [DOI: 10.1016/j.jchromb.2017.12.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 12/01/2017] [Accepted: 12/10/2017] [Indexed: 11/22/2022]
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4
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Ikon N, Shearer J, Liu J, Tran JJ, Feng S, Kamei A, Beckstead JA, Kiss RS, Weers PM, Ren G, Ryan RO. A facile method for isolation of recombinant human apolipoprotein A-I from E. coli. Protein Expr Purif 2017; 134:18-24. [PMID: 28336201 DOI: 10.1016/j.pep.2017.03.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 03/16/2017] [Accepted: 03/17/2017] [Indexed: 12/14/2022]
Abstract
Apolipoprotein (apo) A-I is the major protein component of high-density lipoprotein (HDL) and plays key roles in the Reverse Cholesterol Transport pathway. In the past decade, reconstituted HDL (rHDL) has been employed as a therapeutic agent for treatment of atherosclerosis. The ability of rHDL to promote cholesterol efflux from peripheral cells has been documented to reduce the size of atherosclerotic plaque lesions. However, development of apoA-I rHDL-based therapeutics for human use requires a cost effective process to generate an apoA-I product that meets "Good Manufacturing Practice" standards. Methods available for production and isolation of unmodified recombinant human apoA-I at scale are cumbersome, laborious and complex. To overcome this obstacle, a streamlined two-step procedure has been devised for isolation of recombinant untagged human apoA-I from E. coli that takes advantage of its ability to re-fold to a native conformation following denaturation. Heat treatment of a sonicated E. coli supernatant fraction induced precipitation of a large proportion of host cell proteins (HCP), yielding apoA-I as the major soluble protein. Reversed-phase HPLC of this material permitted recovery of apoA-I largely free of HCP and endotoxin. Purified apoA-I possessed α-helix secondary structure, formed rHDL upon incubation with phospholipid and efficiently promoted cholesterol efflux from cholesterol loaded J774 macrophages.
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Affiliation(s)
- Nikita Ikon
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland CA 94609, USA
| | - Jennifer Shearer
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland CA 94609, USA
| | - Jianfang Liu
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA
| | - Jesse J Tran
- Department of Chemistry and Biochemistry, California State University, Long Beach 1250, Bellflower Boulevard, Long Beach, CA 90840, USA
| | - ShiBo Feng
- Research Institute of the McGill University Health Centre, Glen Site, EM1.2220, 1001 Boul Decarie, Montreal, QCH4A 3J1 Canada
| | - Ayako Kamei
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland CA 94609, USA
| | - Jennifer A Beckstead
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland CA 94609, USA
| | - Robert S Kiss
- Research Institute of the McGill University Health Centre, Glen Site, EM1.2220, 1001 Boul Decarie, Montreal, QCH4A 3J1 Canada
| | - Paul M Weers
- Department of Chemistry and Biochemistry, California State University, Long Beach 1250, Bellflower Boulevard, Long Beach, CA 90840, USA
| | - Gang Ren
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA
| | - Robert O Ryan
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland CA 94609, USA.
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5
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Narasimhan Janakiraman V, Noubhani A, Venkataraman K, Vijayalakshmi M, Santarelli X. High yield of recombinant human Apolipoprotein A-I expressed in Pichia pastoris
by using mixed-mode chromatography. Biotechnol J 2015; 11:117-26. [DOI: 10.1002/biot.201500245] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 10/19/2015] [Accepted: 11/25/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Vignesh Narasimhan Janakiraman
- IPB, Biotechnologie des Protéines Recombinantes à Visée Santé; Bordeaux France
- Univ. Bordeaux, Biotechnologie des Protéines Recombinantes à Visée Santé; Bordeaux France
- Centre for Bio-Separation Technology, VIT University; Vellore India
| | - Abdelmajid Noubhani
- IPB, Biotechnologie des Protéines Recombinantes à Visée Santé; Bordeaux France
- Univ. Bordeaux, Biotechnologie des Protéines Recombinantes à Visée Santé; Bordeaux France
| | | | | | - Xavier Santarelli
- IPB, Biotechnologie des Protéines Recombinantes à Visée Santé; Bordeaux France
- Univ. Bordeaux, Biotechnologie des Protéines Recombinantes à Visée Santé; Bordeaux France
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6
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Nykiforuk CL, Shen Y, Murray EW, Boothe JG, Busseuil D, Rhéaume E, Tardif JC, Reid A, Moloney MM. Expression and recovery of biologically active recombinant Apolipoprotein AI(Milano) from transgenic safflower (Carthamus tinctorius) seeds. PLANT BIOTECHNOLOGY JOURNAL 2011; 9:250-63. [PMID: 20618764 DOI: 10.1111/j.1467-7652.2010.00546.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Apolipoprotein AI Milano (ApoAI(Milano) ) was expressed as a fusion protein in transgenic safflower seeds. High levels of expression corresponding to 7 g of ApoAI(Milano) per kilogram of seed have been identified in a line selected for commercialization. The ApoAI(Milano) fusion protein was extracted from seed using an oilbody-based process and matured in vitro prior to final purification. This yielded a Des-1,2-ApoAI(Milano) product which was confirmed by biochemical characterization including immunoreactivity against ApoAI antibodies, isoelectric point, N-terminal sequencing and electrospray mass spectrometry. Purified Des-1,2-ApoAI(Milano) readily associated with dimyristoylphosphatidylcholine in clearance assays comparable to Human ApoAI. Its biological activity was assessed by cholesterol efflux assays using Des-1,2-ApoAI(Milano) :1-palmitoyl-2-oleoyl phosphatidylcholine complexes in vitro and in vivo. This study has established that high levels of biologically functional ApoAI(Milano) can be produced using a plant-based expression system.
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7
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Brace RJ, Sorrenson B, Sviridov D, McCormick SPA. A gel-based method for purification of apolipoprotein A-I from small volumes of plasma. J Lipid Res 2010; 51:3370-6. [PMID: 20667818 DOI: 10.1194/jlr.d008300] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We present here a gel-based method for rapid purification of apolipoprotein A-I (apoA-I) from small volumes of human plasma. After isolation of high density lipoprotein from plasma, the apoA-I protein was separated by electrophoresis and the apoA-I band excised from the gel. The apoA-I was then eluted from the gel strip, concentrated, and delipidated ready for use. The structure and function of the gel-purified apoA-I protein was compared against apoA-I purified by the traditional size-exclusion chromatography method. The α-helical content of the gel-purified apoA-I as determined by circular dichroism was similar to chromatography-purified apoA-I. The functional activity of gel-purified apoA-I, as determined by cholesterol efflux assays in primary human fibroblasts and RAW264.7 macrophages, was also comparable with chromatography-purified apoA-I. This method is a valid alternative for apoA-I purification with some advantages over traditional chromatography purification including a much reduced plasma volume requirement, less time and cost, and a higher percentage protein recovery. The method is particularly suitable for applications requiring the purification of apoA-I from multiple human or animal samples of interest.
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Affiliation(s)
- Rachel J Brace
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
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8
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Sviridov D. Maturation of apolipoprotein A-I: unrecognized health benefit or a forgotten rudiment? J Lipid Res 2009; 50:1257-8. [PMID: 19332654 DOI: 10.1194/jlr.e900003-jlr200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Dmitri Sviridov
- Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
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9
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Tubb MR, Smith LE, Davidson WS. Purification of recombinant apolipoproteins A-I and A-IV and efficient affinity tag cleavage by tobacco etch virus protease. J Lipid Res 2009; 50:1497-504. [PMID: 19318686 DOI: 10.1194/jlr.d900003-jlr200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The expression of recombinant apolipoproteins provides experimental avenues that are not possible with plasma purified protein. The ability to specifically mutate residues or delete entire regions has proven to be a valuable tool for understanding the structure and function of apolipoproteins. A common feature of many recombinant systems is an affinity tag that allows for straightforward and high-yield purification of the target protein. A specific protease can then cleave the tag and yield the native recombinant protein. However, the application of this strategy to apolipoproteins has proven somewhat problematic because of the tendency for these highly flexible proteins to be nonspecifically cleaved at undesired sites within the native protein. Although systems have been developed using a variety of proteases, many suffer from low yield and, especially, the high cost of the enzyme.We developed a method that utilizes the tobacco etch virus protease to cleave a histidine-tag from apolipoproteins A-I and A-IV expressed in Escherichia coli. This protease can be easily and inexpensively expressed within most laboratories. We found that the protease efficiently cleaved the affinity tags from both apolipoproteins without nonspecific cleavage. All structural and functional measurements showed that the proteins were equivalent to native or previously characterized protein preparations. In addition to cost-effectiveness, advantages of the tobacco etch virus protease include a short cleavage time, low reaction temperature, and easy removal using the protease's own histidine-tag.
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Affiliation(s)
- Matthew R Tubb
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, OH 45237-0507, USA
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10
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Feng MQ, Cai QS, Song DX, Dong JB, Zhou P. High yield and secretion of recombinant human apolipoprotein AI in Pichia pastoris. Protein Expr Purif 2006; 46:337-42. [PMID: 16516487 DOI: 10.1016/j.pep.2005.11.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 11/03/2005] [Accepted: 11/10/2005] [Indexed: 10/25/2022]
Abstract
Apolipoprotein AI (ApoAI) is an important apolipoprotein in plasma and is known to have various physiological functions suitable for pharmaceutical applications. Human blood has been the only source of this protein for research and large-scale applications. To obtain large amounts of ApoAI a Pichia pastoris expression system was first used to obtain a high level of expression of secreted, recombinant protein. The human gene encoding ApoAI was inserted into the secretion vector pPIC9K and used to transform P. pastoris GS115. AP16, a high expression transformant with high G418 resistance, was obtained. After induction with methanol, the expression level of rhApoAI (recombinant human ApoAI) was 160 mg/L in a 14L fermentor. RhApoAI was purified by cold acetone precipitation followed by Q-Sepharose Fast Flow ion exchange column chromatography with 60% recovery. The N-terminal amino acid sequence and molecular weight (mass spec.) of rhApoAI are identical to native human ApoAI. Purified rhApoAI has specific binding activity with liver cells SMC7721 and binding can be inhibited by native human ApoAI.
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Affiliation(s)
- Mei-qing Feng
- School of Pharmacy, Fudan University, Yi Xue Yuan Road 138#, Shanghai 200032, China.
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11
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Sviridov D, Hoang A, Huang W, Sasaki J. Structure-function studies of apoA-I variants:site-directed mutagenesis and natural mutations. J Lipid Res 2002. [DOI: 10.1194/jlr.m100437-jlr200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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12
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Deletion of the propeptide of apolipoprotein A-I reduces protein expression but stimulates effective conversion of preβ-high density lipoprotein to α-high density lipoprotein. J Lipid Res 2000. [DOI: 10.1016/s0022-2275(20)31981-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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13
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Sviridov D, Hoang A, Sawyer WH, Fidge NH. Identification of a sequence of apolipoprotein A-I associated with the activation of Lecithin:Cholesterol acyltransferase. J Biol Chem 2000; 275:19707-12. [PMID: 10781581 DOI: 10.1074/jbc.m000962200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We aimed to distinguish between the effects of mutations in apoA-I on the requirements for the secondary structure and a specific amino acid sequence for lecithin:cholesterol acyltransferase (LCAT) activation. Several mutants were constructed targeting region 140-150: (i) two mutations affecting alpha-helical structure, deletion of amino acids 140-150 and substitution of Ala(143) for proline; (ii) two mutations not affecting alpha-helical structure, substitution of Val(149) for arginine and substitution of amino acids 63-73 for sequence 140-150; and (iii) a mutation in a similar region away from the target area, deletion of amino acids 63-73. All mutations affecting region 140-150 resulted in a 4-42-fold reduction in LCAT activation. Three mutations, apoA-I(Delta140-150), apoA-I(P143A), and apoA-I(140-150 --> 63-73), affected both the apparent V(max) and K(m), whereas the mutation apoA-I(R149V) affected only the V(max). The mutation apoA-I(Delta63-73) caused only a 5-fold increase in the K(m). All mutants, except apoA-I(P143A) and apoA-I(Delta63-73), were active in phospholipid binding assay. All mutants, except apoA-I(P143A), formed normal discoidal complexes with phospholipid. The mutation apoA-I(Delta63-73) caused a significant reduction in the stability of apoA-I.phospholipid complexes in denaturation experiments. Combined, our results strongly suggest that although the correct conformation and orientation of apoA-I in the complex with lipids are crucial for activation of LCAT, when these conditions are fulfilled, activation also strongly depends on the sequence that includes amino acids 140-150.
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Affiliation(s)
- D Sviridov
- Baker Medical Research Institute, Melbourne 8008 and the Department of Biochemistry, University of Melbourne, Parkville 3052, Victoria, Australia.
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Levy E, Bendayan M. Use of immunoelectron microscopy and intestinal models to explore the elaboration of apolipoproteins required for intraenterocyte lipid transport. Microsc Res Tech 2000; 49:374-82. [PMID: 10820521 DOI: 10.1002/(sici)1097-0029(20000515)49:4<374::aid-jemt6>3.0.co;2-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The intestine is the organ that contributes the majority of circulating alimentary lipoproteins. Intestinal epithelial cells have the unique ability to elaborate chylomicrons, the largest triglyceride-rich lipoproteins and the main vehicle for the transport of dietary lipids. The final intracellular assembly and exocytosis of chylomicrons require enterocyte-derived apolipoproteins (apo). As research on lipoprotein metabolism evolved, it has become increasingly evident that apo B is a crucial protein for the normal packaging of triglyceride-rich lipoproteins. Immunocytochemical techniques have successfully been used to demonstrate the presence of two types of apo B, the B-100 and the B-48, in different subcellular compartments of the human enterocyte. Confirmation was obtained by biochemically analyzing human lymph and intestine from pediatric patients. In addition, the immunoelectron microscopic approach revealed the location of apo A-I in the rough endoplasmic reticulum (ER) and predominantly in the Golgi apparatus and the basolateral membrane, which confirms the rapid transport of apo A-I documented by other studies. Proven utility and experimental conditions were defined to demonstrate the ability of Caco-2 cells, a colon carcinoma cell line, to esterify lipids, synthesize apo, and assemble lipoproteins. Thus, immunocytochemical and biochemical techniques can be combined with in vivo and in vitro intestinal models for the study of the intestinal lipid transport.
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Affiliation(s)
- E Levy
- Hôpital Sainte-Justine Research Center, Montréal, Québec, Canada H3T 1C5
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15
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Sviridov D, Luong A, Pyle L, Fidge N. Effectivity of expression of mature forms of mutant human apolipoprotein A-I. Protein Expr Purif 1999; 17:231-8. [PMID: 10545271 DOI: 10.1006/prep.1999.1114] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In order to probe the structural and functional properties of a central region of apolipoprotein A-I (apoA-I), we engineered mutants of the mature form of the protein and expressed them using the baculovirus/insect cell expression system. The mutations which targeted the region of apoA-I between amino acids 140 and 150 included: (i) deletion of the region 140-150 (apoA-I(Delta140-150)); (ii) substitution of arginine 149 with valine (apoA-I(R149V)); (iii) substitution of proline 143 with alanine (apoA-I(P143A)); (iv) deletion of region 63-73 (apoA-I(Delta63-73)), which has structural properties similar to 140-150; and (v) a chimeric protein substituting amino acids 140-150 with amino acids 63-73 (apoA-I(140-150 --> 63-73)). The efficiencies of synthesis were vastly different for the various mutants as follows: apoA-I(R149V) > apoA-I(140-150 --> 63-73) > apoA-I(Delta63-73) > apoA-I(P143A) > apoA-I > apoA-I(Delta140-150). About 50% of the synthesized wild type and all apoA-I mutants was retained in the cells. During expression of apoA-I(R149V) an unusual spontaneous recombination occurred. In addition to the expected mutant, another form of apoA-I with an apparent M(r) of 36K was produced which consisted of a duplication of the amino-terminal end of apoA-I, from the prepeptide through to amino acid 62, linked to the original pre-apoA-I(R149V) sequence via a 4-amino-acid linker. Despite the fact that this form of apoA-I carries two prepeptides and consequently two cleavage sites, there was little, if any, cleavage at the internal cleavage site. During expression, less than 20% of this mutant was retained in the cells. These results demonstrate that at least in the model of insect cells, the efficiency of apoA-I synthesis, processing, and secretion depends on apoA-I secondary structure and/or folding.
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Affiliation(s)
- D Sviridov
- Baker Medical Research Institute, Melbourne, Victoria, 8008, Australia.
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16
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Abstract
The protein components of human lipoproteins, apolipoproteins, allow the redistribution of cholesterol from the arterial wall to other tissues and exert beneficial effects on systems involved in the development of arterial lesions, like inflammation and hemostasis. Because of these properties, the antiatherogenic apolipoproteins, particularly apo A-I and apo E, may provide an innovative approach to the management of vascular diseases. The recent availability of extractive or biosynthetic molecules is allowing a detailed overview of their therapeutic potential in a number of animal models of arterial disease. Infusions of apo E, or more dramatically, of apo A-I, both recombinant or extractive, cause a direct reduction of the atherosclerotic burden in experimental animals. Naturally, as the apo A-I(Milano) (apo A-I(M)) dimer, or engineered recombinant apolipoproteins with prolonged permanence in plasma and improved function may offer an even better approach to the therapeutic handling of arterial disease. This progress will go on in parallel with innovations in the technologies for direct, non invasive assessments of human atherosclerosis, thus allowing closer monitoring of this potential new approach to therapy.
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Affiliation(s)
- C R Sirtori
- Center E. Grossi Paoletti, Institute of Pharmacological Sciences, University of Milano, Italy
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