1
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Villanueva CE, Hagenbuch B. Palmitoylation of solute carriers. Biochem Pharmacol 2023; 215:115695. [PMID: 37481134 PMCID: PMC10530500 DOI: 10.1016/j.bcp.2023.115695] [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: 05/06/2023] [Revised: 07/05/2023] [Accepted: 07/12/2023] [Indexed: 07/24/2023]
Abstract
Post-translational modifications are an important mechanism in the regulation of protein expression, function, and degradation. Well-known post-translational modifications are phosphorylation, glycosylation, and ubiquitination. However, lipid modifications, including myristoylation, prenylation, and palmitoylation, are poorly studied. Since the early 2000s, researchers have become more interested in lipid modifications, especially palmitoylation. The number of articles in PubMed increased from about 350 between 2000 and 2005 to more than 600 annually during the past ten years. S-palmitoylation, where the 16-carbon saturated (C16:0) palmitic acid is added to free cysteine residues of proteins, is a reversible protein modification that can affect the expression, membrane localization, and function of the modified proteins. Various diseases like Huntington's and Alzheimer's disease have been linked to changes in protein palmitoylation. In humans, the addition of palmitic acid is mediated by 23 palmitoyl acyltransferases, also called DHHC proteins. The modification can be reversed by a few thioesterases or hydrolases. Numerous soluble and membrane-attached proteins are known to be palmitoylated, but among the approximately 400 solute carriers that are classified in 66 families, only 15 found in 8 families have so far been documented to be palmitoylated. Among the best-characterized transporters are the glucose transporters GLUT1 (SLC2A1) and GLUT4 (SLC2A4), the three monoamine transporters norepinephrine transporter (NET; SLC6A2), dopamine transporter (DAT; SLC6A3), and serotonin transporter (SERT; SLC6A4), and the sodium-calcium exchanger NCX1 (SLC8A1). While there is evidence from recent proteomics experiments that numerous solute carriers are palmitoylated, no details beyond the 15 transporters covered in this review are available.
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Affiliation(s)
- Cecilia E Villanueva
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, KS 66160, United States
| | - Bruno Hagenbuch
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, KS 66160, United States.
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2
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Sacher S, Mukherjee A, Ray A. Deciphering structural aspects of reverse cholesterol transport: mapping the knowns and unknowns. Biol Rev Camb Philos Soc 2023; 98:1160-1183. [PMID: 36880422 DOI: 10.1111/brv.12948] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 02/03/2023] [Accepted: 02/24/2023] [Indexed: 03/08/2023]
Abstract
Atherosclerosis is a major contributor to the onset and progression of cardiovascular disease (CVD). Cholesterol-loaded foam cells play a pivotal role in forming atherosclerotic plaques. Induction of cholesterol efflux from these cells may be a promising approach in treating CVD. The reverse cholesterol transport (RCT) pathway delivers cholesteryl ester (CE) packaged in high-density lipoproteins (HDL) from non-hepatic cells to the liver, thereby minimising cholesterol load of peripheral cells. RCT takes place via a well-organised interplay amongst apolipoprotein A1 (ApoA1), lecithin cholesterol acyltransferase (LCAT), ATP binding cassette transporter A1 (ABCA1), scavenger receptor-B1 (SR-B1), and the amount of free cholesterol. Unfortunately, modulation of RCT for treating atherosclerosis has failed in clinical trials owing to our lack of understanding of the relationship between HDL function and RCT. The fate of non-hepatic CEs in HDL is dependent on their access to proteins involved in remodelling and can be regulated at the structural level. An inadequate understanding of this inhibits the design of rational strategies for therapeutic interventions. Herein we extensively review the structure-function relationships that are essential for RCT. We also focus on genetic mutations that disturb the structural stability of proteins involved in RCT, rendering them partially or completely non-functional. Further studies are necessary for understanding the structural aspects of RCT pathway completely, and this review highlights alternative theories and unanswered questions.
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Affiliation(s)
- Sukriti Sacher
- Department of Computational Biology, Indraprastha Institute of Information Technology, Okhla Phase III, New Delhi, 110019, India
| | - Abhishek Mukherjee
- Dhiti Life Sciences Pvt Ltd, B-107, Okhla Phase I, New Delhi, 110020, India
| | - Arjun Ray
- Department of Computational Biology, Indraprastha Institute of Information Technology, Okhla Phase III, New Delhi, 110019, India
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3
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Roundhill EA, Pantziarka P, Liddle DE, Shaw LA, Albadrani G, Burchill SA. Exploiting the Stemness and Chemoresistance Transcriptome of Ewing Sarcoma to Identify Candidate Therapeutic Targets and Drug-Repurposing Candidates. Cancers (Basel) 2023; 15:cancers15030769. [PMID: 36765727 PMCID: PMC9913297 DOI: 10.3390/cancers15030769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/08/2023] [Accepted: 01/17/2023] [Indexed: 01/28/2023] Open
Abstract
Outcomes for most patients with Ewing sarcoma (ES) have remained unchanged for the last 30 years, emphasising the need for more effective and tolerable treatments. We have hypothesised that using small-molecule inhibitors to kill the self-renewing chemotherapy-resistant cells (Ewing sarcoma cancer stem-like cells; ES-CSCs) responsible for progression and relapse could improve outcomes and minimise treatment-induced morbidities. For the first time, we demonstrate that ABCG1, a potential oncogene in some cancers, is highly expressed in ES-CSCs independently of CD133. Using functional models, transcriptomics and a bespoke in silico drug-repurposing pipeline, we have prioritised a group of tractable small-molecule inhibitors for further preclinical studies. Consistent with the cellular origin of ES, 21 candidate molecular targets of pluripotency, stemness and chemoresistance were identified. Small-molecule inhibitors to 13 of the 21 molecular targets (62%) were identified. POU5F1/OCT4 was the most promising new therapeutic target in Ewing sarcoma, interacting with 10 of the 21 prioritised molecular targets and meriting further study. The majority of small-molecule inhibitors (72%) target one of two drug efflux proteins, p-glycoprotein (n = 168) or MRP1 (n = 13). In summary, we have identified a novel cell surface marker of ES-CSCs and cancer/non-cancer drugs to targets expressed by these cells that are worthy of further preclinical evaluation. If effective in preclinical models, these drugs and drug combinations might be repurposed for clinical evaluation in patients with ES.
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Affiliation(s)
- Elizabeth Ann Roundhill
- Children’s Cancer Research Group, Leeds Institute of Medical Research, St James’s University Hospital, Beckett Street, Leeds LS9 7TF, UK
- Correspondence: (E.A.R.); (S.A.B.)
| | - Pan Pantziarka
- Anticancer Fund, Brusselsesteenweg 11, 1860 Meise, Belgium
| | - Danielle E. Liddle
- Children’s Cancer Research Group, Leeds Institute of Medical Research, St James’s University Hospital, Beckett Street, Leeds LS9 7TF, UK
| | - Lucy A. Shaw
- Children’s Cancer Research Group, Leeds Institute of Medical Research, St James’s University Hospital, Beckett Street, Leeds LS9 7TF, UK
| | - Ghadeer Albadrani
- Children’s Cancer Research Group, Leeds Institute of Medical Research, St James’s University Hospital, Beckett Street, Leeds LS9 7TF, UK
| | - Susan Ann Burchill
- Children’s Cancer Research Group, Leeds Institute of Medical Research, St James’s University Hospital, Beckett Street, Leeds LS9 7TF, UK
- Correspondence: (E.A.R.); (S.A.B.)
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4
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Wang M, Alabi A, Gu HM, Gill G, Zhang Z, Jarad S, Xia XD, Shen Y, Wang GQ, Zhang DW. Identification of amino acid residues in the MT-loop of MT1-MMP critical for its ability to cleave low-density lipoprotein receptor. Front Cardiovasc Med 2022; 9:917238. [PMID: 36093157 PMCID: PMC9452735 DOI: 10.3389/fcvm.2022.917238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 08/01/2022] [Indexed: 11/13/2022] Open
Abstract
Low-density lipoprotein receptor (LDLR) mediates clearance of plasma LDL cholesterol, preventing the development of atherosclerosis. We previously demonstrated that membrane type 1-matrix metalloproteinase (MT1-MMP) cleaves LDLR and exacerbates the development of atherosclerosis. Here, we investigated determinants in LDLR and MT1-MMP that were critical for MT1-MMP-induced LDLR cleavage. We observed that deletion of various functional domains in LDLR or removal of each of the five predicted cleavage sites of MT1-MMP on LDLR did not affect MT1-MMP-induced cleavage of the receptor. Removal of the hemopexin domain or the C-terminal cytoplasmic tail of MT1-MMP also did not impair its ability to cleave LDLR. On the other hand, mutant MT1-MMP, in which the catalytic domain or the MT-loop was deleted, could not cleave LDLR. Further Ala-scanning analysis revealed an important role for Ile at position 167 of the MT-loop in MT1-MMP’s action on LDLR. Replacement of Ile167 with Ala, Thr, Glu, or Lys resulted in a marked loss of the ability to cleave LDLR, whereas mutation of Ile167 to a non-polar amino acid residue, including Leu, Val, Met, and Phe, had no effect. Therefore, our studies indicate that MT1-MMP does not require a specific cleavage site on LDLR. In contrast, an amino acid residue with a hydrophobic side chain at position 167 in the MT-loop is critical for MT1-MMP-induced LDLR cleavage.
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Affiliation(s)
- Maggie Wang
- The Department of Pediatrics and Group on the Molecular Cell Biology of Lipids, Faculty of Medicine Dentistry, College of Health Sciences, University of Alberta, Edmonton, AB, Canada
| | - Adekunle Alabi
- The Department of Pediatrics and Group on the Molecular Cell Biology of Lipids, Faculty of Medicine Dentistry, College of Health Sciences, University of Alberta, Edmonton, AB, Canada
| | - Hong-mei Gu
- The Department of Pediatrics and Group on the Molecular Cell Biology of Lipids, Faculty of Medicine Dentistry, College of Health Sciences, University of Alberta, Edmonton, AB, Canada
| | - Govind Gill
- The Department of Pediatrics and Group on the Molecular Cell Biology of Lipids, Faculty of Medicine Dentistry, College of Health Sciences, University of Alberta, Edmonton, AB, Canada
| | - Ziyang Zhang
- The Department of Pediatrics and Group on the Molecular Cell Biology of Lipids, Faculty of Medicine Dentistry, College of Health Sciences, University of Alberta, Edmonton, AB, Canada
| | - Suha Jarad
- The Department of Pediatrics and Group on the Molecular Cell Biology of Lipids, Faculty of Medicine Dentistry, College of Health Sciences, University of Alberta, Edmonton, AB, Canada
| | - Xiao-dan Xia
- The Department of Pediatrics and Group on the Molecular Cell Biology of Lipids, Faculty of Medicine Dentistry, College of Health Sciences, University of Alberta, Edmonton, AB, Canada
- Department of Orthopedics, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People’s Hospital, Qingyuan, China
| | - Yishi Shen
- The Department of Pediatrics and Group on the Molecular Cell Biology of Lipids, Faculty of Medicine Dentistry, College of Health Sciences, University of Alberta, Edmonton, AB, Canada
| | - Gui-qing Wang
- Department of Orthopedics, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People’s Hospital, Qingyuan, China
| | - Da-wei Zhang
- The Department of Pediatrics and Group on the Molecular Cell Biology of Lipids, Faculty of Medicine Dentistry, College of Health Sciences, University of Alberta, Edmonton, AB, Canada
- *Correspondence: Da-wei Zhang,
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5
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Wang B, Shen Y, Zhai L, Xia X, Gu HM, Wang M, Zhao Y, Chang X, Alabi A, Xing S, Deng S, Liu B, Wang G, Qin S, Zhang DW. Atherosclerosis-associated hepatic secretion of VLDL but not PCSK9 is dependent on cargo receptor protein Surf4. J Lipid Res 2021; 62:100091. [PMID: 34118252 PMCID: PMC8261665 DOI: 10.1016/j.jlr.2021.100091] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 05/11/2021] [Accepted: 06/01/2021] [Indexed: 02/05/2023] Open
Abstract
Plasma LDL is produced from catabolism of VLDL and cleared from circulation mainly via the hepatic LDL receptor (LDLR). Proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes LDLR degradation, increasing plasma LDL-C levels. Circulating PCSK9 is mainly secreted by the liver, whereas VLDL is exclusively secreted by hepatocytes. However, the mechanism regulating their secretion is not completely understood. Surfeit 4 (Surf4) is a cargo receptor localized in the ER membrane. It recruits cargos into coat protein complex II vesicles to facilitate their secretion. Here, we investigated the role of Surf4 in VLDL and PCSK9 secretion. We generated Surf4 liver-specific knockout mice and found that knockout of Surf4 did not affect PCSK9 secretion, whereas it significantly reduced plasma levels of cholesterol, triglyceride, and lipid-binding protein apolipoprotein B (apoB). In cultured human hepatocytes, Surf4 coimmunoprecipitated and colocalized with apolipoprotein B100, and Surf4 silencing reduced secretion of apolipoprotein B100. Furthermore, knockdown of Surf4 in LDLR knockout (Ldlr−/−) mice significantly reduced triglyceride secretion, plasma levels of apoB and non-HDL-C, and the development of atherosclerosis. However, Surf4 liver-specific knockout mice and Surf4 knockdown in Ldlr−/− mice displayed similar levels of liver lipids and plasma alanine aminotransferase activity as control mice, indicating that inhibition of Surf4 does not cause notable liver damage. Expression of stearoyl-CoA desaturase-1 was also reduced in the liver of these mice, suggesting a reduction in de novo lipogenesis. In summary, hepatic deficiency of Surf4 reduced VLDL secretion and the development of atherosclerosis but did not cause significant hepatic lipid accumulation or liver damage.
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Affiliation(s)
- Bingxiang Wang
- Institute of Atherosclerosis and College of Basic Medical Sciences in Shandong First Medical University (Shandong Academy of Medical Sciences), Taian, China
| | - Yishi Shen
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Lei Zhai
- Institute of Atherosclerosis and College of Basic Medical Sciences in Shandong First Medical University (Shandong Academy of Medical Sciences), Taian, China
| | - Xiaodan Xia
- Department of Orthopedics, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Qingyuan, China
| | - Hong-Mei Gu
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Maggie Wang
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Yongfang Zhao
- Institute of Atherosclerosis and College of Basic Medical Sciences in Shandong First Medical University (Shandong Academy of Medical Sciences), Taian, China
| | - Xiaole Chang
- Institute of Atherosclerosis and College of Basic Medical Sciences in Shandong First Medical University (Shandong Academy of Medical Sciences), Taian, China
| | - Adekunle Alabi
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Sijie Xing
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Shijun Deng
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Boyan Liu
- Institute of Atherosclerosis and College of Basic Medical Sciences in Shandong First Medical University (Shandong Academy of Medical Sciences), Taian, China
| | - Guiqing Wang
- Department of Orthopedics, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Qingyuan, China
| | - Shucun Qin
- Institute of Atherosclerosis and College of Basic Medical Sciences in Shandong First Medical University (Shandong Academy of Medical Sciences), Taian, China.
| | - Da-Wei Zhang
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
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6
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Alabi A, Xia XD, Gu HM, Wang F, Deng SJ, Yang N, Adijiang A, Douglas DN, Kneteman NM, Xue Y, Chen L, Qin S, Wang G, Zhang DW. Membrane type 1 matrix metalloproteinase promotes LDL receptor shedding and accelerates the development of atherosclerosis. Nat Commun 2021; 12:1889. [PMID: 33767172 PMCID: PMC7994674 DOI: 10.1038/s41467-021-22167-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 03/02/2021] [Indexed: 01/07/2023] Open
Abstract
Plasma low-density lipoprotein (LDL) is primarily cleared by LDL receptor (LDLR). LDLR can be proteolytically cleaved to release its soluble ectodomain (sLDLR) into extracellular milieu. However, the proteinase responsible for LDLR cleavage is unknown. Here we report that membrane type 1-matrix metalloproteinase (MT1-MMP) co-immunoprecipitates and co-localizes with LDLR and promotes LDLR cleavage. Plasma sLDLR and cholesterol levels are reduced while hepatic LDLR is increased in mice lacking hepatic MT1-MMP. Opposite effects are observed when MT1-MMP is overexpressed. MT1-MMP overexpression significantly increases atherosclerotic lesions, while MT1-MMP knockdown significantly reduces cholesteryl ester accumulation in the aortas of apolipoprotein E (apoE) knockout mice. Furthermore, sLDLR is associated with apoB and apoE-containing lipoproteins in mouse and human plasma. Plasma levels of sLDLR are significantly increased in subjects with high plasma LDL cholesterol levels. Thus, we demonstrate that MT1-MMP promotes ectodomain shedding of hepatic LDLR, thereby regulating plasma cholesterol levels and the development of atherosclerosis.
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Affiliation(s)
- Adekunle Alabi
- The Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Xiao-Dan Xia
- The Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.,Department of Orthopedics, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Qingyuan, China
| | - Hong-Mei Gu
- The Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Faqi Wang
- The Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Shi-Jun Deng
- The Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Nana Yang
- Experimental Center for Medical Research, Weifang Medical University, Weifang, China
| | - Ayinuer Adijiang
- The Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Donna N Douglas
- Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Norman M Kneteman
- Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Yazhuo Xue
- Institute of Atherosclerosis in Shandong First Medical University (Shandong Academy of Medical Sciences), Taian, China
| | - Li Chen
- Institute of Atherosclerosis in Shandong First Medical University (Shandong Academy of Medical Sciences), Taian, China
| | - Shucun Qin
- Institute of Atherosclerosis in Shandong First Medical University (Shandong Academy of Medical Sciences), Taian, China
| | - Guiqing Wang
- Department of Orthopedics, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Qingyuan, China
| | - Da-Wei Zhang
- The Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.
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7
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Deng SJ, Shen Y, Gu HM, Guo S, Wu SR, Zhang DW. The role of the C-terminal domain of PCSK9 and SEC24 isoforms in PCSK9 secretion. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158660. [DOI: 10.1016/j.bbalip.2020.158660] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/05/2020] [Accepted: 02/07/2020] [Indexed: 12/16/2022]
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Cantin C, Fuenzalida B, Leiva A. Maternal hypercholesterolemia during pregnancy: Potential modulation of cholesterol transport through the human placenta and lipoprotein profile in maternal and neonatal circulation. Placenta 2020; 94:26-33. [DOI: 10.1016/j.placenta.2020.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 03/09/2020] [Accepted: 03/18/2020] [Indexed: 01/28/2023]
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Deng SJ, Alabi A, Gu HM, Adijiang A, Qin S, Zhang DW. Identification of amino acid residues in the ligand binding repeats of LDL receptor important for PCSK9 binding. J Lipid Res 2019; 60:516-527. [PMID: 30617148 PMCID: PMC6399494 DOI: 10.1194/jlr.m089193] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 12/18/2018] [Indexed: 12/13/2022] Open
Abstract
Proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes LDL receptor (LDLR) degradation, increasing plasma levels of LDL cholesterol and the risk of cardiovascular disease. We have previously shown that, in addition to the epidermal growth factor precursor homology repeat-A of LDLR, at least three ligand-binding repeats (LRs) of LDLR are required for PCSK9-promoted LDLR degradation. However, how exactly the LRs contribute to PCSK9’s action on the receptor is not completely understood. Here, we found that substitution of Asp at position 172 in the linker between the LR4 and LR5 of full-length LDLR with Asn (D172N) reduced PCSK9 binding at pH 7.4 (mimic cell surface), but not at pH 6.0 (mimic endosomal environment). On the other hand, mutation of Asp at position 203 in the LR5 of full-length LDLR to Asn (D203N) significantly reduced PCSK9 binding at both pH 7.4 and pH 6.0. D203N also significantly reduced the ability of LDLR to mediate cellular LDL uptake, whereas D172N had no detectable effect. These findings indicate that amino acid residues in the LRs of LDLR play an important role in PCSK9 binding to the receptor.
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Affiliation(s)
- Shi-Jun Deng
- Department of Pediatrics, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada
| | - Adekunle Alabi
- Department of Pediatrics, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada.,Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Hong-Mei Gu
- Department of Pediatrics, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada
| | - Ayinuer Adijiang
- Department of Pediatrics, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada
| | - Shucun Qin
- Institute of Atherosclerosis, Taishan Medical University, Taian, China
| | - Da-Wei Zhang
- Department of Pediatrics, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada .,Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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10
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Zhou CC, Gao ZY, Wang J, Wu MQ, Hu S, Chen F, Liu JX, Pan H, Yan CH. Lead exposure induces Alzheimers’s disease (AD)-like pathology and disturbes cholesterol metabolism in the young rat brain. Toxicol Lett 2018; 296:173-183. [DOI: 10.1016/j.toxlet.2018.06.1065] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/30/2018] [Accepted: 06/12/2018] [Indexed: 02/07/2023]
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11
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Harris MT, Hussain SS, Inouye CM, Castle AM, Castle JD. Reinterpretation of the localization of the ATP binding cassette transporter ABCG1 in insulin-secreting cells and insights regarding its trafficking and function. PLoS One 2018; 13:e0198383. [PMID: 30235209 PMCID: PMC6147399 DOI: 10.1371/journal.pone.0198383] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 09/04/2018] [Indexed: 01/08/2023] Open
Abstract
The ABC transporter ABCG1 contributes to the regulation of cholesterol efflux from cells and to the distribution of cholesterol within cells. We showed previously that ABCG1 deficiency inhibits insulin secretion by pancreatic beta cells and, based on its immunolocalization to insulin granules, proposed its essential role in forming granule membranes that are enriched in cholesterol. While we confirm elsewhere that ABCG1, alongside ABCA1 and oxysterol binding protein OSBP, supports insulin granule formation, the aim here is to clarify the localization of ABCG1 within insulin-secreting cells and to provide added insight regarding ABCG1's trafficking and sites of function. We show that stably expressed GFP-tagged ABCG1 closely mimics the distribution of endogenous ABCG1 in pancreatic INS1 cells and accumulates in the trans-Golgi network (TGN), endosomal recycling compartment (ERC) and on the cell surface but not on insulin granules, early or late endosomes. Notably, ABCG1 is short-lived, and proteasomal and lysosomal inhibitors both decrease its degradation. Following blockade of protein synthesis, GFP-tagged ABCG1 first disappears from the ER and TGN and later from the ERC and plasma membrane. In addition to aiding granule formation, our findings raise the prospect that ABCG1 may act beyond the TGN to regulate activities involving the endocytic pathway, especially as the amount of transferrin receptor is increased in ABCG1-deficient cells. Thus, ABCG1 may function at multiple intracellular sites and the plasma membrane as a roving sensor and modulator of cholesterol distribution, membrane trafficking and cholesterol efflux.
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Affiliation(s)
- Megan T. Harris
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Syed Saad Hussain
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Candice M. Inouye
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Anna M. Castle
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - J. David Castle
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
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12
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Intracellular and Plasma Membrane Events in Cholesterol Transport and Homeostasis. J Lipids 2018; 2018:3965054. [PMID: 30174957 PMCID: PMC6106919 DOI: 10.1155/2018/3965054] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 07/26/2018] [Indexed: 12/13/2022] Open
Abstract
Cholesterol transport between intracellular compartments proceeds by both energy- and non-energy-dependent processes. Energy-dependent vesicular traffic partly contributes to cholesterol flux between endoplasmic reticulum, plasma membrane, and endocytic vesicles. Membrane contact sites and lipid transfer proteins are involved in nonvesicular lipid traffic. Only “active" cholesterol molecules outside of cholesterol-rich regions and partially exposed in water phase are able to fast transfer. The dissociation of partially exposed cholesterol molecules in water determines the rate of passive aqueous diffusion of cholesterol out of plasma membrane. ATP hydrolysis with concomitant conformational transition is required to cholesterol efflux by ABCA1 and ABCG1 transporters. Besides, scavenger receptor SR-B1 is involved also in cholesterol efflux by facilitated diffusion via hydrophobic tunnel within the molecule. Direct interaction of ABCA1 with apolipoprotein A-I (apoA-I) or apoA-I binding to high capacity binding sites in plasma membrane is important in cholesterol escape to free apoA-I. ABCG1-mediated efflux to fully lipidated apoA-I within high density lipoprotein particle proceeds more likely through the increase of “active” cholesterol level. Putative cholesterol-binding linear motifs within the structure of all three proteins ABCA1, ABCG1, and SR-B1 are suggested to contribute to the binding and transfer of cholesterol molecules from cytoplasmic to outer leaflets of lipid bilayer. Together, plasma membrane events and intracellular cholesterol metabolism and traffic determine the capacity of the cell for cholesterol efflux.
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Abstract
Drug transporter proteins are critical to the distribution of a wide range of endogenous compounds and xenobiotics such as hormones, bile acids, peptides, lipids, sugars, and drugs. There are two classes of drug transporters- the solute carrier (SLC) transporters and ATP-binding cassette (ABC) transporters -which predominantly differ in the energy source utilized to transport substrates across a membrane barrier. Despite their hydrophobic nature and residence in the membrane bilayer, drug transporters have dynamic structures and adopt many conformations during the translocation process. Whereas there is significant literature evidence for the substrate specificity and structure-function relationship for clinically relevant drug transporters proteins, there is less of an understanding in the regulatory mechanisms that contribute to the functional expression of these proteins. Post-translational modifications have been shown to modulate drug transporter functional expression via a wide range of molecular mechanisms. These modifications commonly occur through the addition of a functional group (e.g. phosphorylation), a small protein (e.g. ubiquitination), sugar chains (e.g. glycosylation), or lipids (e.g. palmitoylation) on solvent accessible amino acid residues. These covalent additions often occur as a result of a signaling cascade and may be reversible depending on the type of modification and the intended fate of the signaling event. Here, we review the significant role in which post-translational modifications contribute to the dynamic regulation and functional consequences of SLC and ABC drug transporters and highlight recent progress in understanding their roles in transporter structure, function, and regulation.
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Affiliation(s)
- Lindsay C Czuba
- Department of Pharmaceutical Sciences, University of Maryland, 20 Penn Street, Baltimore, MD 21201, USA
| | | | - Peter W Swaan
- Department of Pharmaceutical Sciences, University of Maryland, 20 Penn Street, Baltimore, MD 21201, USA.
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14
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Jiang H, Zhang X, Chen X, Aramsangtienchai P, Tong Z, Lin H. Protein Lipidation: Occurrence, Mechanisms, Biological Functions, and Enabling Technologies. Chem Rev 2018; 118:919-988. [PMID: 29292991 DOI: 10.1021/acs.chemrev.6b00750] [Citation(s) in RCA: 275] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Protein lipidation, including cysteine prenylation, N-terminal glycine myristoylation, cysteine palmitoylation, and serine and lysine fatty acylation, occurs in many proteins in eukaryotic cells and regulates numerous biological pathways, such as membrane trafficking, protein secretion, signal transduction, and apoptosis. We provide a comprehensive review of protein lipidation, including descriptions of proteins known to be modified and the functions of the modifications, the enzymes that control them, and the tools and technologies developed to study them. We also highlight key questions about protein lipidation that remain to be answered, the challenges associated with answering such questions, and possible solutions to overcome these challenges.
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Affiliation(s)
- Hong Jiang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Xiaoyu Zhang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Xiao Chen
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Pornpun Aramsangtienchai
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Zhen Tong
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Hening Lin
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
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15
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Critical Role of the Human ATP-Binding Cassette G1 Transporter in Cardiometabolic Diseases. Int J Mol Sci 2017; 18:ijms18091892. [PMID: 28869506 PMCID: PMC5618541 DOI: 10.3390/ijms18091892] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 08/30/2017] [Accepted: 08/30/2017] [Indexed: 12/15/2022] Open
Abstract
ATP-binding cassette G1 (ABCG1) is a member of the large family of ABC transporters which are involved in the active transport of many amphiphilic and lipophilic molecules including lipids, drugs or endogenous metabolites. It is now well established that ABCG1 promotes the export of lipids, including cholesterol, phospholipids, sphingomyelin and oxysterols, and plays a key role in the maintenance of tissue lipid homeostasis. Although ABCG1 was initially proposed to mediate cholesterol efflux from macrophages and then to protect against atherosclerosis and cardiovascular diseases (CVD), it becomes now clear that ABCG1 exerts a larger spectrum of actions which are of major importance in cardiometabolic diseases (CMD). Beyond a role in cellular lipid homeostasis, ABCG1 equally participates to glucose and lipid metabolism by controlling the secretion and activity of insulin and lipoprotein lipase. Moreover, there is now a growing body of evidence suggesting that modulation of ABCG1 expression might contribute to the development of diabetes and obesity, which are major risk factors of CVD. In order to provide the current understanding of the action of ABCG1 in CMD, we here reviewed major findings obtained from studies in mice together with data from the genetic and epigenetic analysis of ABCG1 in the context of CMD.
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16
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An Y, Zhang DD, Yu HL, Ma WW, Lu YH, Liu QR, Xiao R. 27-Hydroxycholesterol regulates cholesterol synthesis and transport in C6 glioma cells. Neurotoxicology 2017; 59:88-97. [PMID: 28167099 DOI: 10.1016/j.neuro.2017.02.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 02/01/2017] [Accepted: 02/02/2017] [Indexed: 01/19/2023]
Abstract
The oxysterol 27-Hydroxycholesterol (27-OHC) is a major cholesterol metabolite that can cross the blood brain barrier (BBB) from peripheral circulation to the brain. Currently, the role of 27-OHC on cholesterol homeostasis in astrocytes and the underlying mechanisms are not defined. Since all brain cholesterol is essentially synthesized in brain itself and astrocytes as net producers of cholesterol are essential for normal brain function, here we investigated the effects of 27-OHC on cholesterol synthesis and transport in C6 glioma cells. C6 cells were treated with 5, 10 and 20μM 27-OHC for 24h and the cell viability and apoptosis, the cholesterol levels and metabolism-related mediators, genes and proteins were subsequently assessed using cell-counting kit (CCK)-8, Amplex red, ELISA, real-time PCR and Western blot, respectively. We found that 27-OHC decreased cholesterol levels by down-regulating the expression of sterol-regulated element binding protein-1 (SREBP-1a), 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CR) and low density lipoprotein receptor (LDLR) and promoted cholesterol transport by up-regulating the expression of peroxisome proliferator-activated receptors-γ (PPAR-γ), liver X receptor-α (LXR-α), ATP-binding cassette transporter protein family member A1 (ABCA1) and apolipoprotein E (ApoE)genes. Our results suggested that 27-OHC may represent a sensitive modulator of cholesterol metabolism disorder by suppressing cholesterol synthesis and stimulating cholesterol transport in astrocytes.
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Affiliation(s)
- Yu An
- School of Public Health, Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing 100069, China
| | - Dan-Di Zhang
- School of Public Health, Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing 100069, China; Department of Nutrition, Beijing Luhe Hospital Affiliated to Capital Medical University, Beijing 101149, China
| | - Huan-Ling Yu
- School of Public Health, Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing 100069, China
| | - Wei-Wei Ma
- School of Public Health, Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing 100069, China
| | - Yan-Hui Lu
- School of Public Health, Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing 100069, China
| | - Quan-Ri Liu
- School of Public Health, Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing 100069, China
| | - Rong Xiao
- School of Public Health, Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing 100069, China.
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17
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Gu HM, Wang F, Alabi A, Deng S, Qin S, Zhang DW. Identification of an Amino Acid Residue Critical for Plasma Membrane Localization of ATP-Binding Cassette Transporter G1—Brief Report. Arterioscler Thromb Vasc Biol 2016; 36:253-5. [DOI: 10.1161/atvbaha.115.306592] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 12/13/2015] [Indexed: 11/16/2022]
Affiliation(s)
- Hong-mei Gu
- From the Departments of Pediatrics and Biochemistry, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Alberta, Canada (H.-M.G., F.W., A.A., S.D., D.-W.Z.); and Institute of Atherosclerosis in Taishan Medical University, Taian, China (S.Q., D.-W.Z.)
| | - Faqi Wang
- From the Departments of Pediatrics and Biochemistry, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Alberta, Canada (H.-M.G., F.W., A.A., S.D., D.-W.Z.); and Institute of Atherosclerosis in Taishan Medical University, Taian, China (S.Q., D.-W.Z.)
| | - Adekunle Alabi
- From the Departments of Pediatrics and Biochemistry, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Alberta, Canada (H.-M.G., F.W., A.A., S.D., D.-W.Z.); and Institute of Atherosclerosis in Taishan Medical University, Taian, China (S.Q., D.-W.Z.)
| | - Shijun Deng
- From the Departments of Pediatrics and Biochemistry, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Alberta, Canada (H.-M.G., F.W., A.A., S.D., D.-W.Z.); and Institute of Atherosclerosis in Taishan Medical University, Taian, China (S.Q., D.-W.Z.)
| | - Shucun Qin
- From the Departments of Pediatrics and Biochemistry, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Alberta, Canada (H.-M.G., F.W., A.A., S.D., D.-W.Z.); and Institute of Atherosclerosis in Taishan Medical University, Taian, China (S.Q., D.-W.Z.)
| | - Da-wei Zhang
- From the Departments of Pediatrics and Biochemistry, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Alberta, Canada (H.-M.G., F.W., A.A., S.D., D.-W.Z.); and Institute of Atherosclerosis in Taishan Medical University, Taian, China (S.Q., D.-W.Z.)
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18
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Hoque MT, Shah A, More V, Miller DS, Bendayan R. In vivo and ex vivo regulation of breast cancer resistant protein (Bcrp) by peroxisome proliferator-activated receptor alpha (Pparα) at the blood-brain barrier. J Neurochem 2015; 135:1113-22. [PMID: 26465636 DOI: 10.1111/jnc.13389] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 09/15/2015] [Accepted: 09/16/2015] [Indexed: 12/13/2022]
Abstract
Breast cancer resistance protein (Bcrp/Abcg2) localized at the blood-brain barrier (BBB) limits permeability into the brain of many xenobiotics, including pharmacological agents. Peroxisome proliferator-activated receptor α (Pparα), a ligand-activated transcription factor, primarily involved in lipid metabolism, has been shown to regulate the functional expression of Bcrp in human cerebral microvascular endothelial cells (hCMEC/D3). The aim of this study was to investigate ex vivo and in vivo, the regulation of Bcrp by Pparα in an intact BBB. Ex vivo quantitative real-time PCR and immunoblot analyses showed significant up-regulation of Abcg2/Bcrp mRNA and protein levels in CD-1 mouse brain capillaries incubated with clofibrate, a Pparα ligand. Fluorescence-based transport assays in CD-1 and C57BL/6 brain capillaries showed that exposure to clofibrate significantly increased Bcrp transport activity. This increase was not observed in capillaries isolated from Pparα knockout mice. In vivo, we found: i) significant Bcrp protein up-regulation in clofibrate-dosed CD-1 and C57BL/6 capillary lysates, but no effect in Pparα knockout capillary lysates, and ii) significantly increased Bcrp transport activity in capillaries isolated from clofibrate-treated mice. These results demonstrate an increase in Bcrp functional expression by Pparα in brain capillaries, and suggest that Pparα is another nuclear receptor that can contribute to the regulation of membrane efflux transporters and drug permeability at the BBB. We propose the involvement of the following pathways in clofibrate-mediated induction of the drug transporter Abcg2/Bcrp mRNA, protein expression and function by the nuclear receptor Pparα, in mouse brain capillary endothelial cells. Upon activation with clofibrate (Pparα, ligand), Pparα complex translocates from the cytoplasm into the nucleus and further recruits coactivators and transcription machinery which induce the transcription of Abcg2 gene and ultimately results in upregulation of Bcrp protein expression and function. These findings have significant implications since Bcrp is known to play an important role at the BBB in preventing the permeability of several xenobiotics and drugs into the brain.
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Affiliation(s)
- Md Tozammel Hoque
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Arpit Shah
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Vijay More
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - David S Miller
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Reina Bendayan
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
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19
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Abstract
Protein S-acylation, the only fully reversible posttranslational lipid modification of proteins, is emerging as a ubiquitous mechanism to control the properties and function of a diverse array of proteins and consequently physiological processes. S-acylation results from the enzymatic addition of long-chain lipids, most typically palmitate, onto intracellular cysteine residues of soluble and transmembrane proteins via a labile thioester linkage. Addition of lipid results in increases in protein hydrophobicity that can impact on protein structure, assembly, maturation, trafficking, and function. The recent explosion in global S-acylation (palmitoyl) proteomic profiling as a result of improved biochemical tools to assay S-acylation, in conjunction with the recent identification of enzymes that control protein S-acylation and de-acylation, has opened a new vista into the physiological function of S-acylation. This review introduces key features of S-acylation and tools to interrogate this process, and highlights the eclectic array of proteins regulated including membrane receptors, ion channels and transporters, enzymes and kinases, signaling adapters and chaperones, cell adhesion, and structural proteins. We highlight recent findings correlating disruption of S-acylation to pathophysiology and disease and discuss some of the major challenges and opportunities in this rapidly expanding field.
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Affiliation(s)
- Luke H Chamberlain
- Strathclyde Institute of Pharmacy and Biomedical Sciences, Strathclyde University, Glasgow, United Kingdom; and Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Michael J Shipston
- Strathclyde Institute of Pharmacy and Biomedical Sciences, Strathclyde University, Glasgow, United Kingdom; and Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom
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20
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Scumaci D, Trimboli F, Dell’Aquila L, Concolino A, Pappaianni G, Tammè L, Vignola G, Luciani A, Morelli D, Cuda G, Boari A, Britti D. Proteomics-driven analysis of ovine whey colostrum. PLoS One 2015; 10:e0117433. [PMID: 25643159 PMCID: PMC4313942 DOI: 10.1371/journal.pone.0117433] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 12/22/2014] [Indexed: 02/05/2023] Open
Abstract
The aim of this study was to shed light in to the complexity of the ovine colostrum proteome, with a specific focus on the low abundance proteins. The ovine colostrum is characterized by a few dominating proteins, as the immunoglobulins, but it also contains less represented protein species, equally important for the correct development of neonates. Ovine colostrum, collected immediately after lambing, was separated by 1D SDS-PAGE. Proteins bands were digested with trypsin and the resulting peptides were analyzed by LC-MS/MS. On the basis of the Swiss-Prot database, a total of 343 unique proteins were identified. To our knowledge, this study represents the most comprehensive analysis of ovine colostrum proteome.
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Affiliation(s)
- Domenica Scumaci
- Dpt. of Experimental and Clinical Medicine, Magna Græcia University of Catanzaro, Catanzaro, Italy
| | - Francesca Trimboli
- Dpt. of Health Science, Magna Græcia University of Catanzaro, Catanzaro, Italy
| | | | - Antonio Concolino
- Dpt. of Experimental and Clinical Medicine, Magna Græcia University of Catanzaro, Catanzaro, Italy
| | - Giusi Pappaianni
- Dpt. of Experimental and Clinical Medicine, Magna Græcia University of Catanzaro, Catanzaro, Italy
| | - Laura Tammè
- Dpt. of Experimental and Clinical Medicine, Magna Græcia University of Catanzaro, Catanzaro, Italy
| | - Giorgio Vignola
- Faculty of Veterinary Medicine, University of Teramo, Teramo, Italy
| | - Alessia Luciani
- Faculty of Veterinary Medicine, University of Teramo, Teramo, Italy
| | - Daniela Morelli
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise (IZSAM) “G. Caporale”, Teramo, Italy
| | - Giovanni Cuda
- Dpt. of Experimental and Clinical Medicine, Magna Græcia University of Catanzaro, Catanzaro, Italy
- * E-mail:
| | - Andrea Boari
- Faculty of Veterinary Medicine, University of Teramo, Teramo, Italy
| | - Domenico Britti
- Dpt. of Health Science, Magna Græcia University of Catanzaro, Catanzaro, Italy
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21
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Kardassis D, Gafencu A, Zannis VI, Davalos A. Regulation of HDL genes: transcriptional, posttranscriptional, and posttranslational. Handb Exp Pharmacol 2015; 224:113-179. [PMID: 25522987 DOI: 10.1007/978-3-319-09665-0_3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
HDL regulation is exerted at multiple levels including regulation at the level of transcription initiation by transcription factors and signal transduction cascades; regulation at the posttranscriptional level by microRNAs and other noncoding RNAs which bind to the coding or noncoding regions of HDL genes regulating mRNA stability and translation; as well as regulation at the posttranslational level by protein modifications, intracellular trafficking, and degradation. The above mechanisms have drastic effects on several HDL-mediated processes including HDL biogenesis, remodeling, cholesterol efflux and uptake, as well as atheroprotective functions on the cells of the arterial wall. The emphasis is on mechanisms that operate in physiologically relevant tissues such as the liver (which accounts for 80% of the total HDL-C levels in the plasma), the macrophages, the adrenals, and the endothelium. Transcription factors that have a significant impact on HDL regulation such as hormone nuclear receptors and hepatocyte nuclear factors are extensively discussed both in terms of gene promoter recognition and regulation but also in terms of their impact on plasma HDL levels as was revealed by knockout studies. Understanding the different modes of regulation of this complex lipoprotein may provide useful insights for the development of novel HDL-raising therapies that could be used to fight against atherosclerosis which is the underlying cause of coronary heart disease.
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Affiliation(s)
- Dimitris Kardassis
- Department of Biochemistry, University of Crete Medical School and Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology of Hellas, Heraklion, Crete, 71110, Greece,
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22
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Gu HM, Wang FQ, Zhang DW. Caveolin-1 interacts with ATP binding cassette transporter G1 (ABCG1) and regulates ABCG1-mediated cholesterol efflux. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:847-58. [DOI: 10.1016/j.bbalip.2014.02.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 02/06/2014] [Accepted: 02/12/2014] [Indexed: 01/19/2023]
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23
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Li G, Gu HM, Zhang DW. ATP-binding cassette transporters and cholesterol translocation. IUBMB Life 2014; 65:505-12. [PMID: 23983199 DOI: 10.1002/iub.1165] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 02/22/2013] [Indexed: 01/26/2023]
Abstract
Cholesterol, a major component of mammalian cell membranes, plays important structural and functional roles. However, accumulation of excessive cholesterol is toxic to cells. Aberrant cholesterol trafficking and accumulation is the molecular basis for many diseases, such as atherosclerotic cardiovascular disease and Tangier's disease. Accumulation of excessive cholesterol is also believed to contribute to the early onset of Alzheimer's disease. Thus, cellular cholesterol homeostasis is tightly regulated by uptake, de novo synthesis, and efflux. Any surplus of cholesterol must either be stored in the cytosol in the form of esters or released from the cell. Recently, several ATP-binding cassette (ABC) transporters, such as ABCA1, ABCG1, ABCG5, and ABCG8 have been shown to play important roles in the regulation of cellular cholesterol homeostasis by mediating cholesterol efflux. Mutations in ABC transporters are associated with several human diseases. In this review, we discuss the physiological roles of ABC transporters and the underlying mechanisms by which they mediate cholesterol translocation.
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Affiliation(s)
- Ge Li
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
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24
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Blaskovic S, Adibekian A, Blanc M, van der Goot GF. Mechanistic effects of protein palmitoylation and the cellular consequences thereof. Chem Phys Lipids 2014; 180:44-52. [PMID: 24534427 DOI: 10.1016/j.chemphyslip.2014.02.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 01/31/2014] [Accepted: 02/03/2014] [Indexed: 12/21/2022]
Abstract
S-palmitoylation involves the attachment of a 16-carbon long fatty acid chain to the cysteine residues of proteins. The process is enzymatic and dynamic with DHHC enzymes mediating palmitoylation and acyl-protein thioesterases reverting the reaction. Proteins that undergo this modification span almost all cellular functions. While the increase in hydrophobicity generated by palmitoylation has the obvious consequence of triggering membrane association, the effects on transmembrane proteins are less intuitive and span a vast range. We review here the current knowledge on palmitoylating and depalmitoylating enzymes, the methods that allow the study of this lipid modification and which drugs can affect it, and finally we focus on four cellular processes for which recent studies reveal an involvement of palmitoylation: endocytosis, reproduction and cell growth, fat and sugar homeostasis and signal transduction at the synapse.
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Affiliation(s)
- Sanja Blaskovic
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 19, CH-1015 Lausanne, Switzerland
| | - Alexander Adibekian
- Department of Organic Chemistry, University of Geneva, 1211 Geneva, Switzerland
| | - Mathieu Blanc
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 19, CH-1015 Lausanne, Switzerland
| | - Gisou F van der Goot
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 19, CH-1015 Lausanne, Switzerland.
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25
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Wang F, Li G, Gu HM, Zhang DW. Characterization of the role of a highly conserved sequence in ATP binding cassette transporter G (ABCG) family in ABCG1 stability, oligomerization, and trafficking. Biochemistry 2013; 52:9497-509. [PMID: 24320932 PMCID: PMC3880014 DOI: 10.1021/bi401285j] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
![]()
ATP-binding cassette transporter
G1 (ABCG1) mediates cholesterol
and oxysterol efflux onto lipidated lipoproteins and plays an important
role in macrophage reverse cholesterol transport. Here, we identified
a highly conserved sequence present in the five ABCG transporter family
members. The conserved sequence is located between the nucleotide
binding domain and the transmembrane domain and contains five amino
acid residues from Asn at position 316 to Phe at position 320 in ABCG1
(NPADF). We found that cells expressing mutant ABCG1, in which Asn316,
Pro317, Asp319, and Phe320 in the conserved sequence were replaced
with Ala simultaneously, showed impaired cholesterol efflux activity
compared with wild type ABCG1-expressing cells. A more detailed mutagenesis
study revealed that mutation of Asn316 or Phe 320 to Ala significantly
reduced cellular cholesterol and 7-ketocholesterol efflux conferred
by ABCG1, whereas replacement of Pro317 or Asp319 with Ala had no
detectable effect. To confirm the important role of Asn316 and Phe320,
we mutated Asn316 to Asp (N316D) and Gln (N316Q), and Phe320 to Ile
(F320I) and Tyr (F320Y). The mutant F320Y showed the same phenotype
as wild type ABCG1. However, the efflux of cholesterol and 7-ketocholesterol
was reduced in cells expressing ABCG1 mutant N316D, N316Q, or F320I
compared with wild type ABCG1. Further, mutations N316Q and F320I
impaired ABCG1 trafficking while having no marked effect on the stability
and oligomerization of ABCG1. The mutant N316Q and F320I could not
be transported to the cell surface efficiently. Instead, the mutant
proteins were mainly localized intracellularly. Thus, these findings
indicate that the two highly conserved amino acid residues, Asn and
Phe, play an important role in ABCG1-dependent export of cellular
cholesterol, mainly through the regulation of ABCG1 trafficking.
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Affiliation(s)
- Faqi Wang
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, ‡Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta , Edmonton, Alberta T6G 2S2, Canada
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26
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Gu HM, Adijiang A, Mah M, Zhang DW. Characterization of the role of EGF-A of low density lipoprotein receptor in PCSK9 binding. J Lipid Res 2013; 54:3345-57. [PMID: 24103783 DOI: 10.1194/jlr.m041129] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Proprotein convertase subtilisin kexin-like 9 (PCSK9) promotes the degradation of low density lipoprotein receptor (LDLR) and plays an important role in regulating plasma LDL-cholesterol levels. We have shown that the epidermal growth factor precursor homology domain A (EGF-A) of the LDLR is critical for PCSK9 binding at the cell surface (pH 7.4). Here, we further characterized the role of EGF-A in binding of PCSK9 to the LDLR. We found that PCSK9 efficiently bound to the LDLR but not to other LDLR family members. Replacement of EGF-A in the very low density lipoprotein receptor (VLDLR) with EGF-A of the LDLR promoted the degradation of the mutant VLDLR induced by PCSK9. Furthermore, we found that PCSK9 bound to recombinant EGF-A in a pH-dependent manner with stronger binding at pH 6.0. We also identified amino acid residues in EGF-A of the LDLR important for PCSK9 binding. Mutations G293H, D299V, L318D, and L318H reduced PCSK9 binding to the LDLR at neutral pH without effect at pH 6.0, while mutations R329P and E332G reduced PCSK9 binding at both pH values. Thus, our findings reveal that EGF-A of the LDLR is critical for PCSK9 binding at the cell surface (neutral pH) and at the acidic endosomal environment (pH 6.0), but different determinants contribute to efficient PCSK9 binding in different pH environments.
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Affiliation(s)
- Hong-mei Gu
- Departments of Pediatrics and Biochemistry, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
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27
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Li G, Gu HM, Zhang DW. ATP-binding cassette transporters and cholesterol translocation. IUBMB Life 2013:n/a-n/a. [PMID: 23625363 DOI: 10.1002/iub.01165] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 02/22/2013] [Indexed: 11/08/2022]
Abstract
Cholesterol, a major component of mammalian cell membranes, plays important structural and functional roles. However, accumulation of excessive cholesterol is toxic to cells. Aberrant cholesterol trafficking and accumulation is the molecular basis for many diseases, such as atherosclerotic cardiovascular disease and Tangier's disease. Accumulation of excessive cholesterol is also believed to contribute to the early onset of Alzheimer's disease. Thus, cellular cholesterol homeostasis is tightly regulated by uptake, de novo synthesis, and efflux. Any surplus of cholesterol must either be stored in the cytosol in the form of esters or released from the cell. Recently, several ATP-binding cassette (ABC) transporters, such as ABCA1, ABCG1, ABCG5, and ABCG8 have been shown to play important roles in the regulation of cellular cholesterol homeostasis by mediating cholesterol efflux. Mutations in ABC transporters are associated with several human diseases. In this review, we discuss the physiological roles of ABC transporters and the underlying mechanisms by which they mediate cholesterol translocation. © 2013 IUBMB Life, 2013.
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Affiliation(s)
- Ge Li
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, AB, Canada
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