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Abstract
Multidrug resistance (MDR) is a major impediment to curative cancer chemotherapy. The ATP-Binding Cassette transporters ABCG2, ABCB1 and ABCC2 form a unique defense network against multiple structurally and functionally distinct chemotherapeutics, thereby resulting in MDR. Thus, deciphering novel mechanisms of MDR and their overcoming is a major goal of cancer research. Recently we have shown that overexpression of ABCG2 in the membrane of novel extracellular vesicles (EVs) in breast cancer cells results in mitoxantrone resistance due to its dramatic sequestration in EVs. However, nothing is known about EVs structure, biogenesis and their ability to concentrate multiple antitumor agents. To this end, we here found that EVs are structural and functional homologues of bile canaliculi, are apically localized, sealed structures reinforced by an actin-based cytoskeleton and secluded from the extracellular milieu by the tight junction proteins occludin and ZO-1. Apart from ABCG2, ABCB1 and ABCC2 were also selectively targeted to the membrane of EVs. Moreover, Ezrin-Radixin-Moesin protein complex selectively localized to the border of the EVs membrane, suggesting a key role for the tethering of MDR pumps to the actin cytoskeleton. The ability of EVs to concentrate and sequester different antitumor drugs was also explored. Taking advantage of the endogenous fluorescence of anticancer drugs, we found that EVs-forming breast cancer cells display high level resistance to topotecan, imidazoacridinones and methotrexate via efficient intravesicular drug concentration hence sequestering them away from their cellular targets. Thus, we identified a new modality of anticancer drug compartmentalization and resistance in which multiple chemotherapeutics are actively pumped from the cytoplasm and highly concentrated within the lumen of EVs via a network of MDR transporters differentially targeted to the EVs membrane. We propose a composite model for the structure and function of MDR pump-rich EVs in cancer cells and their ability to confer multiple anticancer drug resistance.
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Affiliation(s)
- Vicky Goler-Baron
- The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yehuda G. Assaraf
- The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
- * E-mail:
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102
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Abstract
X-linked adrenoleukodystrophy (ALD) is caused by mutations in the ABCD1 gene that encodes a protein of the peroxisomal membrane named ALDP. Mutations in ALDP result in elevated levels of very long chain fatty acids (VLCFA) and reduced VLCFA oxidation in peroxisomes. Three main phenotypes are seen in affected males. The childhood cerebral form manifests usually between ages 4 and 8 years. It initially resembles attention deficit disorder or hyperactivity. Progressive central demyelination with impairment of cognition, behavior, vision, hearing, and motor function follow the initial symptoms and often lead to total disability within 2 years. The second phenotype, adrenomyeloneuropathy, manifests most commonly in the late twenties as progressive paraparesis, sphincter disturbances, sexual dysfunction, and often, impaired adrenocortical function; all symptoms are progressive over decades. The third phenotype, 'Addison disease only', presents with primary adrenocortical insufficiency between age 2 years and adulthood and most commonly by age 7.5 years, without evidence of neurologic abnormality. Approximately 50% of females who are carriers develop neurologic manifestations that resemble adrenomyeloneuropathy but have a later onset (age ≥35 years) and a milder disease. In this review, we will give an overview of the present understanding of ALD, and the implications of new diagnostics and treatment.
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103
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Chen L, Wang W, Zhu Q, Du F. [Biosynthesis mechanisms of bacterial polysaccharide--a review]. Wei Sheng Wu Xue Bao 2010; 50:1583-1589. [PMID: 21365910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Bacterial polysaccharides play important roles both in medicine and industry. Due to the development of bacterial genome sequencing, many gene clusters related to the biosynthesis of bacterial polysaccharide have been found, aligned and analyzed. Despite of their complex composition and structures, different bacterial polysaccharides are biosynthesized via similar pathways. This review discussed the research development of the biosynthetic mechanism of different bacterial polysaccharides, with emphasis on the glycosyltransferases and polymerases involved in the biosynthetic pathway.
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Affiliation(s)
- Leilei Chen
- Institute of Agro-Food Science & Technology, Shandong Academy of Agricultural Sciences, Jinan 250100, China.
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104
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Taichi M, Nishiuchi Y. [Structure and function of marinostatin, a serine protease inhibitor]. Seikagaku 2010; 82:1032-1036. [PMID: 21226332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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105
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Yoon JH, Kuver R, Choi HS. ABCG8 D19H polymorphism: a basis for the genetic prediction of cholesterol gallstone disease. J Gastroenterol Hepatol 2010; 25:1713-4. [PMID: 21039829 DOI: 10.1111/j.1440-1746.2010.06484.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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106
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Höftberger R, Kunze M, Voigtländer T, Unterberger U, Regelsberger G, Bauer J, Aboul-Enein F, Garzuly F, Forss-Petter S, Bernheimer H, Berger J, Budka H. Peroxisomal localization of the proopiomelanocortin-derived peptides beta-lipotropin and beta-endorphin. Endocrinology 2010; 151:4801-10. [PMID: 20810565 DOI: 10.1210/en.2010-0249] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The peptide hormones ACTH, MSHs, β-lipotropin (β-LPH), and β-endorphin are all derived from the precursor molecule proopiomelanocortin (POMC). Using confocal laser microscopy and immunoelectron microscopy in human pituitary gland, we demonstrate a peroxisomal localization of β-endorphin and β-LPH in cells expressing the peroxisomal ATP-binding cassette-transporter adrenoleukodystrophy protein (ALDP). The peroxisomal localization of β-LPH and β-endorphin was not restricted to the pituitary gland but was additionally found in other human tissues that express high levels of ALDP, such as dorsal root ganglia, adrenal cortex, distal tubules of kidney, and skin. In contrast to the peptide hormones β-LPH and β-endorphin, which are derived from the C terminus of POMC, the N-terminal peptides ACTH, α-MSH, and γ-MSH were never detected in peroxisomes. This novel peroxisomal localization of β-endorphin and β-LPH in ALDP-positive cells was confirmed by costaining with ALDP and the peroxisomal marker catalase. Moreover, peroxisomal sorting of β-LPH could be modeled in HeLa cells by ectopic expression of a POMC variant, modified to allow cleavage and release of β-LPH within the secretory pathway. Although β-LPH and β-endorphin were only associated with peroxisomes in cells that normally express ALDP, the transporter activity of ALDP is not necessary for the peroxisomal localization, as demonstrated in tissues of X-linked adrenoleukodystrophy patients lacking functional ALDP. It remains to be elucidated whether and how the peroxisomal localization of POMC-derived hormones has a role in the endocrine dysfunction of peroxisomal disease.
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Affiliation(s)
- Romana Höftberger
- Institute of Neurology, Center for Brain Research, Medical University of Vienna, and Department of Neurology, SMZ-Ost Danube Hospital, AKH 4J, Währinger Gürtel 18-20, P.O. Box 48, A-1097 Vienna, Austria.
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107
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Wei N, Sun H, Liu GT. [Advances in the targeting ATP-binding cassette transporters to overcome tumor multi-drug resistance]. Yao Xue Xue Bao 2010; 45:1205-1211. [PMID: 21348297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
ATP-binding cassette (ABC) transporters are a family of proteins that mediate multi-drug resistance (MDR) via ATP-dependent drug efflux pumps. Abnormally expression and function would result in tumor MDR. That is the most important mechanism of MDR. The inhibition of ABC transporters as a strategy to reverse MDR in cancer has been studied extensively. In this review, we reviewed the structure and function of ABC transporters, and focused on the research advances in the mechanism of tumors MDR mediated by ABC transporters and the development of their modulators and reversal strategies.
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Affiliation(s)
- Ning Wei
- Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
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108
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Nishimaki-Mogami T. [Dual regulation of hepatic ABCA1 gene expression]. Seikagaku 2010; 82:852-856. [PMID: 20960923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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109
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Abstract
The ATP-sensitive potassium (K(ATP)) channel is composed of two subunits SUR1 and Kir6.2. The channel is key for glucose stimulated insulin release from the pancreatic beta cell. Activating mutations have been identified in the genes encoding these subunits, ABCC8 and KCNJ11, and account for approximately 40% of permanent neonatal diabetes cases. The majority of patients with a K(ATP) mutation present with isolated diabetes however some have presented with the Developmental delay, Epilepsy and Neonatal Diabetes syndrome. This review focuses on mutations in the K(ATP) channel which result in permanent neonatal diabetes, we review the clinical and functional effects as well as the implications for treatment.
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MESH Headings
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- ATP-Binding Cassette Transporters/physiology
- Diabetes Mellitus/congenital
- Diabetes Mellitus/genetics
- Diabetes Mellitus/therapy
- Genetic Association Studies
- Humans
- Infant, Newborn
- Infant, Newborn, Diseases/genetics
- Infant, Newborn, Diseases/therapy
- KATP Channels/genetics
- KATP Channels/metabolism
- KATP Channels/physiology
- Models, Biological
- Mutation/physiology
- Potassium Channels, Inwardly Rectifying/genetics
- Potassium Channels, Inwardly Rectifying/metabolism
- Potassium Channels, Inwardly Rectifying/physiology
- Receptors, Drug/genetics
- Receptors, Drug/metabolism
- Receptors, Drug/physiology
- Sulfonylurea Receptors
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Affiliation(s)
- Emma L Edghill
- Institute of Biomedical and Clinical Science, Peninsula College of Medicine and Dentistry, University of Exeter, Barrack Road, Exeter, UK
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110
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Jeandet P, Delaunois B, Conreux A, Donnez D, Nuzzo V, Cordelier S, Clément C, Courot E. Biosynthesis, metabolism, molecular engineering, and biological functions of stilbene phytoalexins in plants. Biofactors 2010; 36:331-41. [PMID: 20726013 DOI: 10.1002/biof.108] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Stilbenic compounds recently have become the focus of a number of studies in medicine and plant physiology as well as have emerged as promising molecules that potentially affect human health. Stilbenes are relatively simple compounds synthesized by plants and deriving from the phenyalanine/polymalonate route, the last and key enzyme of this pathway being stilbene synthase. Here, we review the biological significance of stilbenes in plants together with their biosynthesis pathway and their metabolism both by fungi and in planta. Special attention will be paid to the role of stilbenic molecules as phytoalexins.
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111
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Snyder AK, Deberry JW, Runyen-Janecky L, Rio RVM. Nutrient provisioning facilitates homeostasis between tsetse fly (Diptera: Glossinidae) symbionts. Proc Biol Sci 2010; 277:2389-97. [PMID: 20356887 PMCID: PMC2894912 DOI: 10.1098/rspb.2010.0364] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2010] [Accepted: 03/09/2010] [Indexed: 11/12/2022] Open
Abstract
Host-associated microbial interactions may involve genome complementation, driving-enhanced communal efficiency and stability. The tsetse fly (Diptera: Glossinidae), the obligate vector of African trypanosomes (Trypanosoma brucei subspp.), harbours two enteric Gammaproteobacteria symbionts: Wigglesworthia glossinidia and Sodalis glossinidius. Host coevolution has streamlined the Wigglesworthia genome to complement the exclusively sanguivorous tsetse lifestyle. Comparative genomics reveal that the Sodalis genome contains the majority of Wigglesworthia genes. This significant genomic overlap calls into question why tsetse maintains the coresidence of both symbionts and, furthermore, how symbiont homeostasis is maintained. One of the few distinctions between the Wigglesworthia and Sodalis genomes lies in thiamine biosynthesis. While Wigglesworthia can synthesize thiamine, Sodalis lacks this capability but retains a thiamine ABC transporter (tbpAthiPQ) believed to salvage thiamine. This genetic complementation may represent the early convergence of metabolic pathways that may act to retain Wigglesworthia and evade species antagonism. We show that thiamine monophosphate, the specific thiamine derivative putatively synthesized by Wigglesworthia, impacts Sodalis thiamine transporter expression, proliferation and intracellular localization. A greater understanding of tsetse symbiont interactions may generate alternative control strategies for this significant medical and agricultural pest, while also providing insight into the evolution of microbial associations within hosts.
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Affiliation(s)
- Anna K. Snyder
- Department of Biology, West Virginia University, 53 Campus Drive 5106 LSB, Morgantown, WV 26506, USA
| | - Jason W. Deberry
- Department of Biology, West Virginia University, 53 Campus Drive 5106 LSB, Morgantown, WV 26506, USA
| | | | - Rita V. M. Rio
- Department of Biology, West Virginia University, 53 Campus Drive 5106 LSB, Morgantown, WV 26506, USA
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112
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Hanley TM, Blay Puryear W, Gummuluru S, Viglianti GA. PPARgamma and LXR signaling inhibit dendritic cell-mediated HIV-1 capture and trans-infection. PLoS Pathog 2010; 6:e1000981. [PMID: 20617179 PMCID: PMC2895661 DOI: 10.1371/journal.ppat.1000981] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 06/02/2010] [Indexed: 12/22/2022] Open
Abstract
Dendritic cells (DCs) contribute to human immunodeficiency virus type 1 (HIV-1) transmission and dissemination by capturing and transporting infectious virus from the mucosa to draining lymph nodes, and transferring these virus particles to CD4+ T cells with high efficiency. Toll-like receptor (TLR)-induced maturation of DCs enhances their ability to mediate trans-infection of T cells and their ability to migrate from the site of infection. Because TLR-induced maturation can be inhibited by nuclear receptor (NR) signaling, we hypothesized that ligand-activated NRs could repress DC-mediated HIV-1 transmission and dissemination. Here, we show that ligands for peroxisome proliferator-activated receptor gamma (PPARgamma) and liver X receptor (LXR) prevented proinflammatory cytokine production by DCs and inhibited DC migration in response to the chemokine CCL21 by preventing the TLR-induced upregulation of CCR7. Importantly, PPARgamma and LXR signaling inhibited both immature and mature DC-mediated trans-infection by preventing the capture of HIV-1 by DCs independent of the viral envelope glycoprotein. PPARgamma and LXR signaling induced cholesterol efflux from DCs and led to a decrease in DC-associated cholesterol, which has previously been shown to be required for DC capture of HIV-1. Finally, both cholesterol repletion and the targeted knockdown of the cholesterol transport protein ATP-binding cassette A1 (ABCA1) restored the ability of NR ligand treated cells to capture HIV-1 and transfer it to T cells. Our results suggest that PPARgamma and LXR signaling up-regulate ABCA1-mediated cholesterol efflux from DCs and that this accounts for the decreased ability of DCs to capture HIV-1. The ability of NR ligands to repress DC mediated trans-infection, inflammation, and DC migration underscores their potential therapeutic value in inhibiting HIV-1 mucosal transmission.
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Affiliation(s)
- Timothy M. Hanley
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Wendy Blay Puryear
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Suryaram Gummuluru
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Gregory A. Viglianti
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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113
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Chikazawa N, Tanaka H, Tasaka T, Nakamura M, Tanaka M, Onishi H, Katano M. Inhibition of Wnt signaling pathway decreases chemotherapy-resistant side-population colon cancer cells. Anticancer Res 2010; 30:2041-2048. [PMID: 20651349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
BACKGROUND The prognosis of advanced or recurrent colorectal cancer is still poor. Dye-effluxing side population (SP) colon cancer cells are reportedly resistant to chemotherapeutic agents. Most sporadic colorectal cancers involve constitutive activation of the Wnt signaling pathway. In this study, we examined the effect of the Wnt signaling on SP cells and the possibility that inhibition of Wnt signaling may decrease the resistance to chemotherapeutic drugs in the human colon cancer cells. MATERIALS AND METHODS Drug resistance of SP cells to 5-fluorouracil (5-FU) and irinotecan, decrease of SP cells by the Wnt signaling inhibition and activation of the Wnt signaling of the sorted SP cells were examined using the SW480 colon cancer cell line. mRNA expressions of ATP-binding cassette (ABC) transporters when Wnt signaling was inhibited were evaluated with real-time PCR using colon cancer cell lines (SW480, DLD-1, HCT116, HT29 and LOVO). The sensitivity to irinotecan and paclitaxel when the Wnt signaling was inhibited was investigated using SW480. Inhibition of Wnt signaling was performed by siRNA of beta-catenin. RESULTS SP cells showed more resistance to 5-FU and irinotecan, and higher activation of the Wnt signaling pathway, than non-SP cells. Silencing of beta-catenin decreased significantly more SP cells than non-SP cells. Expression of ABC transporter genes, such as ABCB1 and ABCG2, was significantly higher in SP cells than non-SP cells. Silencing of beta-catenin decreased transcription of these ABC transporter genes; beta-catenin-silenced cells became relatively sensitive to paclitaxel and irinotecan. CONCLUSION These results indicate that inhibiting the Wnt signaling pathway may be a fruitful strategy for targeting chemotherapy-resistant colon cancer cells, including SP cells.
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Affiliation(s)
- Nobuhito Chikazawa
- Department of Cancer Therapy and Research, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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114
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Cho HY, Yoo HD, Lee YB. Influence of ABCB1 genetic polymorphisms on the pharmacokinetics of levosulpiride in healthy subjects. Neuroscience 2010; 169:378-87. [PMID: 20438811 DOI: 10.1016/j.neuroscience.2010.04.065] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 04/20/2010] [Accepted: 04/26/2010] [Indexed: 01/11/2023]
Abstract
The purposes of this study were to clarify the involvement of P-glycoprotein in the absorption of levosulpiride in knockout mice that lack the Abcb1a/ 1b gene, and to evaluate the relationship between genetic polymorphisms in ABCB1 (exon 12, 21 and 26) and levosulpiride disposition in healthy subjects. The plasma and brain samples were obtained after oral administration (10 microg/g) of levosulpiride to abcb1a/1b(-/-) and wild-type mice (n=3 approximately 6 at each time point). The average brain-to-plasma concentration ratio and blood-brain barrier partitioning of levosulpiride were 2.3- and 2.0-fold higher in Abcb1a/1b(-/-) mice than in wild-type mice, respectively. A total of 58 healthy Korean volunteers receiving a single oral dose of 25 mg levosulpiride participated in this study. The subjects were evaluated for polymorphisms of the ABCB1 exon 12 C1236T, exon 21 G2677A/T (Ala893Ser/Thr) and exon 26 C3435T using polymerase chain reaction restriction fragment length polymorphism. The PK parameters (AUC(0-4h), AUC(0-infinity) and C(max.)) of ABCB1 2677TT and 3435TT subjects were significantly higher than those of subjects with at least one wild-type allele (P<0.05). The results indicate that levosulpiride is a P-glycoprotein substrate in vivo, which is supported by the effects of SNPs 2677G>A/T in exon 21 and 3435C>T in exon 26 of ABCB1 on levosulpiride disposition.
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Affiliation(s)
- H Y Cho
- Clinical Trials Management Division, Korea Food & Drug Administration, 194 Tongilro, Eunpyeong-gu, Seoul, 122-704, Republic of Korea
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115
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Leveziel N, Puche N, Zerbib J, Benlian P, Coscas G, Soubrane G, Souied E. [Genetic factors associated with age-related macular degeneration]. Med Sci (Paris) 2010; 26:509-15. [PMID: 20510150 DOI: 10.1051/medsci/2010265509] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Age related macular degeneration (AMD) is the leading cause of vision loss in the elderly in developed countries. Genetic factors play a major role in this multifactorial and polygenic disease. Genomewide analysis identified two loci on 1q25-31 and 10q26 chromosomes associated with AMD, and association studies highlighted the implication of SNPs located in the complement H factor gene (CFH) on 1q25-31 and in PLEKHA1-HTRA1-LOC387715 on 10q26 in the disease. Homozygous carriers for the at-risk alleles of the CFH, HTRA1, and LOC387715 genes have an increased risk to develop exudative AMD with odds ratio of 6.2, 6.9, et 7.3 respectively. Moreover, other genes involved in the complement cascade, namely the genes of the C2, C3 component, and factor B, are associated to the disease. The SCARB1 gene has also recently been associated to AMD. Genotype-phenotype correlations have been performed in AMD patients and found that occult CNV are more often associated to CFH at-risk allele and classic CNV to HTRA1 at-risk allele. This last allele seems also linked to more severe forms of the disease. These new major genetic factors could lead to a new clinical approach of AMD and to the discovery of new therapeutic targets.
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Affiliation(s)
- Nicolas Leveziel
- hôpital intercommunal de Créteil, avenue de Verdun, Créteil, France.
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116
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Abstract
Iron-sulfur (Fe/S) proteins are a class of ubiquitous components that assist in vital and diverse biochemical tasks in virtually every living cell. These tasks include respiration, iron homeostasis and gene expression. The past decade has led to the discovery of novel Fe/S proteins and insights into how their Fe/S cofactors are formed and incorporated into apoproteins. This review summarizes our current knowledge of mammalian Fe/S proteins, diseases related to deficiencies in these proteins and on disorders stemming from their defective biogenesis. Understanding both the physiological functions of Fe/S proteins and how Fe/S clusters are formed will undoubtedly enhance our ability to identify and treat known disorders of Fe/S cluster biogenesis and to recognize hitherto undescribed Fe/S cluster-related diseases.
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Affiliation(s)
- Alex Sheftel
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Strasse 6, D-35033 Marburg, Germany
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117
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Popmihajlov Z, Santori FR, Gebreselassie D, Sandler AD, Vukmanovic S. Effective adoptive therapy of tap-deficient lymphoma using diverse high avidity alloreactive T cells. Cancer Immunol Immunother 2010; 59:629-33. [PMID: 20020123 PMCID: PMC11030666 DOI: 10.1007/s00262-009-0805-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Accepted: 12/01/2009] [Indexed: 12/15/2022]
Abstract
High avidity for antigen and diversity of T cell receptor (TCR) repertoire are essential for effective immunity against cancer. We have previously created a transgenic mouse strain with increased TCR avidity in a diverse T cell population. In this report, we show that strong alloreactive responses of transgenic T cells against targets with low MHC class I expression can be used for effective adoptive transfer of tumor immunity in vivo. Alloreactive transgenic T cells could be an effective therapeutic approach counteracting tumor evasion of the immune system.
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Affiliation(s)
- Zoran Popmihajlov
- Michael Heidelberger Division of Immunology, Department of Pathology and NYU Cancer Center, NYU School of Medicine, New York, NY 10016 USA
- Present Address: Division of Immunology, Department of Medicine, Weill Medical College of Cornell University, 515 East 71st Street, S-222, New York, NY 10021 USA
| | - Fabio R. Santori
- Michael Heidelberger Division of Immunology, Department of Pathology and NYU Cancer Center, NYU School of Medicine, New York, NY 10016 USA
- Present Address: Department of Pathology, Skirball Institute for Molecular Medicine, NYU Cancer Center, NYU School of Medicine, 550 First Avenue, New York, NY 10016 USA
| | - Daniel Gebreselassie
- Center for Cancer and Immunology Research, Children’s Research Institute, Children’s National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010-2970 USA
- Present Address: Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, 3800 Reservoir Rd. N.W, Washington, DC 20057 USA
| | - Anthony D. Sandler
- Center for Cancer and Immunology Research, Children’s Research Institute, Children’s National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010-2970 USA
| | - Stanislav Vukmanovic
- Michael Heidelberger Division of Immunology, Department of Pathology and NYU Cancer Center, NYU School of Medicine, New York, NY 10016 USA
- Center for Cancer and Immunology Research, Children’s Research Institute, Children’s National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010-2970 USA
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118
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Vanderlinde EM, Harrison JJ, Muszyński A, Carlson RW, Turner RJ, Yost CK. Identification of a novel ABC transporter required for desiccation tolerance, and biofilm formation in Rhizobium leguminosarum bv. viciae 3841. FEMS Microbiol Ecol 2010; 71:327-40. [PMID: 20030718 PMCID: PMC2868943 DOI: 10.1111/j.1574-6941.2009.00824.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Rhizobium leguminosarum is a soil bacterium with the ability to form nitrogen-fixing nodules on the roots of leguminous plants. Soil-dwelling, free-living R. leguminosarum often encounters desiccation stress, which impacts its survival within the soil. The mechanisms by which soil bacteria resist the effects of desiccation stress have been described. However, the role of the cell envelope in the desiccation tolerance mechanisms of rhizobia is relatively uncharacterized. Using a transposon mutagenesis approach, a mutant of R. leguminosarum bv. viciae was isolated that was highly sensitive to desiccation. The mutation is located in the ATP-binding protein of an uncharacterized ATP-binding cassette transporter operon (RL2975-RL2977). Exopolysaccharide accumulation was significantly lower in the mutant and the decrease in desiccation tolerance was attributed to the decreased accumulation of exopolysaccharide. In addition to desiccation sensitivity, the mutant was severely impaired in biofilm formation, an important adaptation used by soil bacteria for survival. This work has identified a novel transporter required for physiological traits that are important for the survival of R. leguminosarum in the rhizosphere environment.
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Affiliation(s)
| | - Joe J. Harrison
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Artur Muszyński
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | - Russell W. Carlson
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | - Raymond J. Turner
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
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Koldamova R, Fitz NF, Lefterov I. The role of ATP-binding cassette transporter A1 in Alzheimer's disease and neurodegeneration. Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1801:824-30. [PMID: 20188211 DOI: 10.1016/j.bbalip.2010.02.010] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 02/12/2010] [Accepted: 02/15/2010] [Indexed: 01/03/2023]
Abstract
ATP-binding cassette transporter A1 - ABCA1, is the most extensively studied transporter in human pathology. ABCA1 became a primary subject of research in many academic and pharmaceutical laboratories immediately after the discovery that mutations at the gene locus cause severe familial High Density Lipoprotein (HDL) deficiency and, in the homozygous form - Tangier disease. The protein is the major regulator of intracellular cholesterol efflux which is the initial and essential step in the biogenesis and formation of nascent HDL particles. The transcriptional regulation of ABCA1 by nuclear Liver X Receptors (LXR) provided a starting point for drug discovery and development of synthetic LXR ligands/ABCA1 activators for treatment of arteriosclerosis. A series of reports that revealed the role of ABCA1 in Abeta deposition and clearance, as well as the possibility for association of some ABCA1 genetic variants with risk for Alzheimer's disease (AD) brought a new dimension to ABCA1 research. The LXR-ABCA1-APOE regulatory axis is now considered a promising therapeutic target in AD, which includes the only proven risk factor for AD - APOE, at two distinct levels - transcriptional regulation by LXR, and ABCA1 controlled lipidation which can influence Abeta aggregation and amyloid clearance. This review will summarize the results of research on ABCA1, particularly related to AD and neurodegeneration.
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Affiliation(s)
- Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
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120
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Abstract
Abstract
Mitoquinone (MitoQ10 mesylate) is a mitochondria-targeted antioxidant formulated for oral administration in the treatment of neurodegenerative diseases. We have investigated the absorption and metabolism of MitoQ10 in Caco-2 cell monolayers. The intracellular accumulation of MitoQ10 was 18–41% of the total amount of MitoQ10 added. Some of the intracellular MitoQ10 was reduced to mitoquinol and subsequently metabolized to glucuronide and sulfate conjugates. Transport of MitoQ10 was polarized with the apparent permeability (Papp) from basolateral (BL) to apical (AP) (PappBL→AP) being >2.5-fold the Papp from apical to basolateral (PappAP→BL). In the presence of 4% bovine serum albumin on the basolateral side, the PappAP→BL value increased 7-fold compared with control. The PappBL→AP value decreased by 26, 31 and 61% in the presence of verapamil 100 μM, ciclosporin 10 and 30 μM, respectively, whereas the PappAP→BL value increased 71% in the presence of ciclosporin 30 μM. Apical efflux of mitoquinol sulfate and mitoquinol glucuronide conjugates was significantly decreased by ciclosporin 30 μM and the breast cancer receptor protein (BCRP) inhibitor, reserpine 25 μM, respectively. These results suggested that the bioavailability of MitoQ10 may be limited by intracellular metabolism and the action of P-glycoprotein and BCRP. However, the dramatic increase in absorptive Papp in the presence of bovine serum albumin on the receiver side suggests these barrier functions may be less significant in-vivo.
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Affiliation(s)
- Yan Li
- School of Pharmacy, University of Otago, Dunedin, PO Box 913, New Zealand.
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121
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Lamping E, Baret PV, Holmes AR, Monk BC, Goffeau A, Cannon RD. Fungal PDR transporters: Phylogeny, topology, motifs and function. Fungal Genet Biol 2010; 47:127-42. [PMID: 19857594 PMCID: PMC2814995 DOI: 10.1016/j.fgb.2009.10.007] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 10/15/2009] [Indexed: 10/20/2022]
Abstract
The overexpression of pleiotropic drug resistance (PDR) efflux pumps of the ATP-binding cassette (ABC) transporter superfamily frequently correlates with multidrug resistance. Phylogenetic analysis of 349 full-size ( approximately 160kDa) PDR proteins (Pdrps) from 55 fungal species, including major fungal pathogens, identified nine separate protein clusters (A-G, H1a/H1b and H2). Fungal, plant and human ABCG-family Pdrps possess a nucleotide-binding domain [NBD] and a transmembrane domain [TMD] in a family-defining 'reverse' ABC transporter topology [NBD-TMD] that is duplicated [NBD-TMD](2) in full-size fungal and plant Pdrps. Although full-size Pdrps have similar halves indicating early gene duplication/fusion, they show asymmetry of their NBDs and extracellular loops (ELs). Members of cluster F are most symmetric and may be closely related to the evolutionary ancestor of Pdrps. Unique structural elements are predicted, new PDR-specific motifs identified, and the significance of these and other structural features discussed.
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Affiliation(s)
- Erwin Lamping
- Department of Oral Sciences, University of Otago, Dunedin, New Zealand
| | | | - Ann R. Holmes
- Department of Oral Sciences, University of Otago, Dunedin, New Zealand
| | - Brian C. Monk
- Department of Oral Sciences, University of Otago, Dunedin, New Zealand
| | - Andre Goffeau
- Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Richard D. Cannon
- Department of Oral Sciences, University of Otago, Dunedin, New Zealand
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Miyoshi N, Ishii H, Mimori K, Tanaka F, Nagai K, Uemura M, Sekimoto M, Doki Y, Mori M. ATP11A is a novel predictive marker for metachronous metastasis of colorectal cancer. Oncol Rep 2010; 23:505-510. [PMID: 20043114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023] Open
Abstract
The adenosine triphosphate-binding cassette transporter-homologous gene ATP11A belongs to an extended family of adenosine triphosphate-binding cassette transporters. We analysed the ATP11A gene in 7 colorectal cancer cell lines and 95 paired cases of colorectal cancer and non-cancerous regions to demonstrate the importance of ATP11A expression in colorectal cancer prognosis. ATP11A was expressed in the 7 colorectal cancer cell lines. ATP11A mRNA expression was higher in colorectal cancer tissue than in corresponding normal tissue (P<0.001). Patients with high ATP11A expression showed a poorer disease-free survival rate compared to those with low expression (P<0.001), thus indicating that increase in ATP11A expression was an independent predictor of metachronous metastasis of colorectal cancer. The present study suggests that ATP11A is a useful predictive marker of metastasis in colorectal cancer patients.
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Affiliation(s)
- Norikatsu Miyoshi
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
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123
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Shimomura K, de Nanclares GP, Foutinou C, Caimari M, Castaño L, Ashcroft FM. The first clinical case of a mutation at residue K185 of Kir6.2 (KCNJ11): a major ATP-binding residue. Diabet Med 2010; 27:225-9. [PMID: 20546268 DOI: 10.1111/j.1464-5491.2009.02901.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Closure of the adenosine triphosphate (ATP)-sensitive potassium (K(ATP)) channel plays a key role in insulin secretion from the pancreatic beta-cells. Many mutations in KCNJ11 and ABCC8, which respectively encode the pore-forming (Kir6.2) and regulatory (SUR1) subunits of the K(ATP) channel, cause neonatal diabetes. All such mutations impair the ability of metabolically generated ATP to close the channel. Although lysine 185 is predicted to be a major contributor to the ATP-binding site of Kir6.2, no mutations at this residue have been found to cause neonatal diabetes to date. METHODS We report a 3-year-old girl with permanent neonatal diabetes (PNDM) caused by a novel heterozygous mutation (K185Q) at residue K185 of KCNJ11. The patient presented with marked hyperglycaemia and ketoacidosis at 70 days after birth, and insulin therapy was commenced. RESULTS Wild-type and mutant K(ATP) channels were expressed in Xenopus oocytes and the effects of intracellular ATP on macroscopic K(ATP) currents in inside-out membrane patches were measured. In the simulated heterozygous state, the K185Q mutation caused a substantial reduction in the ability of MgATP to inhibit the channel. Heterozygous K185Q channels were still blocked effectively by the sulphonylurea tolbutamide. CONCLUSIONS We report the first clinical case of a PNDM caused by a mutation at K185. Functional studies indicate that the K185Q mutation causes PNDM by reducing the ATP sensitivity of the K(ATP) channel, probably via a reduction in ATP binding to Kir6.2. Based on the experimental data, the patient was successfully transferred to sulphonylurea therapy.
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Affiliation(s)
- K Shimomura
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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124
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Abstract
Multidrug transporter proteins are best known for their contributions to chemoresistance through the efflux of anticancer drugs from cancer cells. However, a considerable body of evidence also points to their importance in cancer extending beyond drug transport to fundamental roles in tumour biology. Currently, much of the evidence for these additional roles is correlative and definitive studies are needed to confirm causality. We propose that delineating the precise roles of these transporters in tumorigenesis and treatment response will be important for the development of more effective targeted therapies.
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Affiliation(s)
- Jamie I Fletcher
- Children's Cancer Institute Australia for Medical Research, Lowry Cancer Research Centre, University of New South Wales, P.O. BOX 151, Randwick NSW 2031, Australia
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125
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/physiology
- ATP Binding Cassette Transporter, Subfamily B, Member 11
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/physiology
- Biliary Tract/metabolism
- Biological Transport
- Drug Interactions
- Humans
- Liver/metabolism
- Multidrug Resistance-Associated Protein 2
- Multidrug Resistance-Associated Proteins/genetics
- Multidrug Resistance-Associated Proteins/physiology
- Organic Anion Transporters/genetics
- Organic Anion Transporters/physiology
- Organic Anion Transporters, Sodium-Dependent/genetics
- Organic Anion Transporters, Sodium-Dependent/physiology
- Pharmacokinetics
- Polymorphism, Genetic
- Symporters/genetics
- Symporters/physiology
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126
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Teschner J, Lachmann N, Schulze J, Geisler M, Selbach K, Santamaria-Araujo J, Balk J, Mendel RR, Bittner F. A novel role for Arabidopsis mitochondrial ABC transporter ATM3 in molybdenum cofactor biosynthesis. Plant Cell 2010; 22:468-80. [PMID: 20164445 PMCID: PMC2845412 DOI: 10.1105/tpc.109.068478] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 12/29/2009] [Accepted: 02/03/2010] [Indexed: 05/18/2023]
Abstract
The molybdenum cofactor (Moco) is a prosthetic group required by a number of enzymes, such as nitrate reductase, sulfite oxidase, xanthine dehydrogenase, and aldehyde oxidase. Its biosynthesis in eukaryotes can be divided into four steps, of which the last three are proposed to occur in the cytosol. Here, we report that the mitochondrial ABC transporter ATM3, previously implicated in the maturation of extramitochondrial iron-sulfur proteins, has a crucial role also in Moco biosynthesis. In ATM3 insertion mutants of Arabidopsis thaliana, the activities of nitrate reductase and sulfite oxidase were decreased to approximately 50%, whereas the activities of xanthine dehydrogenase and aldehyde oxidase, whose activities also depend on iron-sulfur clusters, were virtually undetectable. Moreover, atm3 mutants accumulated cyclic pyranopterin monophosphate, the first intermediate of Moco biosynthesis, but showed decreased amounts of Moco. Specific antibodies against the Moco biosynthesis proteins CNX2 and CNX3 showed that the first step of Moco biosynthesis is localized in the mitochondrial matrix. Together with the observation that cyclic pyranopterin monophosphate accumulated in purified mitochondria, particularly in atm3 mutants, our data suggest that mitochondria and the ABC transporter ATM3 have a novel role in the biosynthesis of Moco.
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Affiliation(s)
- Julia Teschner
- Institut für Pflanzenbiologie, Technische Universität Braunschweig, 38023 Braunschweig, Germany
| | - Nicole Lachmann
- Institut für Pflanzenbiologie, Technische Universität Braunschweig, 38023 Braunschweig, Germany
| | - Jutta Schulze
- Institut für Pflanzenbiologie, Technische Universität Braunschweig, 38023 Braunschweig, Germany
| | - Mirco Geisler
- Institut für Pflanzenbiologie, Technische Universität Braunschweig, 38023 Braunschweig, Germany
| | - Kristina Selbach
- Institut für Pflanzenbiologie, Technische Universität Braunschweig, 38023 Braunschweig, Germany
| | | | - Janneke Balk
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Ralf R. Mendel
- Institut für Pflanzenbiologie, Technische Universität Braunschweig, 38023 Braunschweig, Germany
- Address correspondence to
| | - Florian Bittner
- Institut für Pflanzenbiologie, Technische Universität Braunschweig, 38023 Braunschweig, Germany
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127
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Abstract
Dysregulation of cholesterol balance contributes significantly to atherosclerotic cardiovascular disease (ASCVD), the leading cause of death in the United States. The intestine has the unique capability to act as a gatekeeper for entry of cholesterol into the body, and inhibition of intestinal cholesterol absorption is now widely regarded as an attractive non-statin therapeutic strategy for ASCVD prevention. In this chapter we discuss the current state of knowledge regarding sterol transport across the intestinal brush border membrane. The purpose of this work is to summarize substantial progress made in the last decade in regards to protein-mediated sterol trafficking, and to discuss this in the context of human disease.
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Affiliation(s)
| | - Liqing Yu
- Address correspondence to: Liqing Yu, M.D., Ph.D., Department of Pathology Section on Lipid Sciences, Wake Forest University School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157-1040, Tel: 336-716-0920, Fax: 336-716-6279,
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128
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Edwards AG, Rees ML, Gioscia RA, Zachman DK, Lynch JM, Browder JC, Chicco AJ, Moore RL. PKC-permitted elevation of sarcolemmal KATP concentration may explain female-specific resistance to myocardial infarction. J Physiol 2009; 587:5723-37. [PMID: 19805744 PMCID: PMC2805381 DOI: 10.1113/jphysiol.2009.181040] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 09/30/2009] [Indexed: 11/08/2022] Open
Abstract
The female myocardium, relative to that of the male, exhibits sustained resistance to ischaemic tissue injury, a phenomenon termed sex-specific cardioprotection (SSC). SSC is dependent upon the sarcolemmal K(ATP) channel (sarcK(ATP)), and protein kinase C (PKC). Here we investigate whether PKC-mediated regulation of sarcK(ATP) concentration can explain this endogenous form of protection. Hearts from male (M) and female (F) rats were Langendorff-perfused for 30 min prior to either regional ischaemia-reperfusion (I/R), or global ischaemia (GISC). For both protocols, pre-ischaemic blockade of PKC was achieved by chelerythrine (Chel) in male (M + C) and female (F + C) hearts. Additional female hearts underwent sarcK(ATP) antagonism during I/R by HMR-1098 (HMR), either alone or in combination with Chel (HMR + Chel). GISC hearts were fractionated to assess cellular distribution of PKC and sarcK(ATP). Sex-specific infarct resistance was apparent under control I/R (F, 23 +/- 3% vs. M, 36 +/- 4%, P < 0.05) and abolished by Chel (F + C, 36 +/- 3%). Female infarct resistance was susceptible to sarcK(ATP) blockade (Control, 16 +/- 2% vs. HMR, 27 +/- 3%), and PKC blockade had no additional effect (HMR + Chel, 26 +/- 2%). The prevalence of Kir6.2 and SUR2 was higher in the sarcolemmal fractions of females (Kir6.2: F, 1.24 +/- 0.07 vs. M, 1.02 +/- 0.06; SUR2: F, 3.16 +/- 0.22 vs. M, 2.45 +/- 0.09; ratio units), but normalized by Chel (Kir6.2: F, 1.06 +/- 0.07 vs. M, 0.99 +/- 0.06; SUR2: F, 2.99 +/- 0.09 vs. M, 2.82 +/- 0.22, M; ratio units). Phosphorylation of sarcolemmal PKC was reduced by Chel (p-PKC/PKC: control, 0.43 +/- 0.02; Chel, 0.29 +/- 0.01; P < 0.01). We conclude that PKC-mediated regulation of sarcK(ATP) may account for the physiologically sustainable dependence of SSC upon both PKC and sarcK(ATP), and that this regulation involves PKC-permitted enrichment of the female sarcolemma with sarcK(ATP). As such, the PKC-sarcK(ATP) axis may represent a target for sustainable prophylactic induction of cardioprotection.
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Affiliation(s)
- Andrew G Edwards
- University of Colorado at Boulder, 354 UCB, Boulder, CO 80309-0354, USA
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129
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Abstract
It is well established that low high-density lipoprotein (HDL) cholesterol is a risk factor for coronary artery disease (CAD). Growing evidence from epidemiologic as well as intervention studies have identified that a low level of HDL cholesterol contributes to cardiovascular disease risk. In addition, a number of clinical trials have substantiated that an inverse association between HDL cholesterol concentrations and cardiovascular risk exists. Decreasing low-density lipoprotein cholesterol levels with statins has a major impact on cardiovascular risk reduction, and statin therapy plays a significant role in the management of CAD. However, low levels of HDL cholesterol remain as a cardiovascular risk factor despite statin therapy. This article presents an overview of statin clinical trials and discusses implications for the clinical management of patients with low HDL cholesterol levels and increased cardiovascular risk.
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Affiliation(s)
- Prakash Deedwania
- Veterans Affairs Central California Health Care System/University of California-San Francisco, 2615 East Clinton Avenue, Fresno, California 93703, USA.
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130
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Gopal RA, Acharya SV, Bandgar TR, Menon PS, Shah NS. A case of neonatal diabetes. J Indian Med Assoc 2009; 107:822-824. [PMID: 20469787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A one month old baby was admitted for diabetic keto-acidosis. There was no neurological or dysmorphic features. On genetic analysis a heterozygous missense mutation of ABCC8 gene which codes for SUR1 was detected. His insulin requirement progressively came down and by 6 months insulin was stopped and child now maintains normoglycaemia. Activating mutation in sulphonylurea receptor SUR1 is a very rare but described cause of neonatal diabetes mellitus.
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Affiliation(s)
- Raju A Gopal
- Department of Endocrinology, Seth GS Medical College and KEM Hospital, Mumbai 400012
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131
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Alexander ET, Weibel GL, Joshi MR, Vedhachalam C, de la Llera-Moya M, Rothblat GH, Phillips MC, Rader DJ. Macrophage reverse cholesterol transport in mice expressing ApoA-I Milano. Arterioscler Thromb Vasc Biol 2009; 29:1496-501. [PMID: 19661486 PMCID: PMC2943867 DOI: 10.1161/atvbaha.109.191379] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE To compare the abilities of human wild-type apoA-I (WT apoA-I) and human apoA-I(Milano) (apoA-I(M)) to promote macrophage reverse cholesterol transport (RCT) in apoA-I-null mice infected with adeno-associated virus (AAV) expressing either WT apoA-I or apoA-I(M). METHODS AND RESULTS WT apoA-I- or apoA-I(M)-expressing mice were intraperitoneally injected with [H(3)]cholesterol-labeled J774 mouse macrophages. After 48 hours, no significant difference was detected in the amount of cholesterol removed from the macrophages and deposited in the feces via the RCT pathway between the WT apoA-I and apoA-I(M) groups. Analysis of the individual components of the RCT pathway demonstrated that the apoA-I(M)-expressing mice promoted ATP-binding cassette transporter A1 (ABCA1)-mediated cholesterol efflux as efficiently as WT apoA-I but that apoA-I(M) had a reduced ability to promote cholesterol esterification via lecithin cholesterol-acyltransferase (LCAT). This resulted in reduced cholesteryl ester (CE) and increased free cholesterol (FC) levels in the plasma of mice expressing apoA-I(M) compared to WT apoA-I. These differences did not affect the rate of delivery of labeled cholesterol to the liver via SR-BI-mediated selective uptake or its subsequent excretion in the feces. CONCLUSIONS Within the limits of the in vivo assay, WT apoA-I and apoA-I(M) are equally efficient at promoting macrophage RCT, suggesting that if apoA-I(M) is more atheroprotective than WT apoA-I it is not attributable to an enhancement of macrophage RCT.
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Affiliation(s)
- Eric T Alexander
- Lipid Research Group, Children's Hospital of Philadelphia, Philadelphia, PA, USA
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132
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Mitra P, Audus KL. MRP isoforms and BCRP mediate sulfate conjugate efflux out of BeWo cells. Int J Pharm 2009; 384:15-23. [PMID: 19782739 DOI: 10.1016/j.ijpharm.2009.09.033] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 09/14/2009] [Accepted: 09/18/2009] [Indexed: 11/17/2022]
Abstract
The breast cancer resistance protein (BCRP) and the multidrug resistance-associated proteins (MRPs) have the ability to eliminate sulfate conjugates but it is not known if this constitutes one of their roles in the placenta. To determine this, the BeWo cell line was used as a model of placental trophoblast cells and the mechanisms of elimination of sulfate metabolites of two common sulfotransferase substrates, 4-nitrophenol and acetaminophen were examined. At 0.5-200 microM, neither 4-nitrophenyl sulfate nor acetaminophen sulfate affected the accumulation of the BCRP substrates BODIPY FL prazosin or mitoxantrone in BeWo monolayers, indicating a lack of interaction of BCRP with the sulfates. Examination of the effect of BCRP/MRP inhibitors on the efflux of intracellularly generated 4-nitrophenyl sulfate and acetaminophen sulfate, indicated that one or more of the MRP isoforms play a major role in the elimination of 4-nitrophenyl sulfate and acetaminophen sulfate across the basolateral (fetal-facing) and apical (maternal-facing) membranes respectively. BCRP played a minor role in the elimination of these two sulfate conjugates across the apical membrane. This study demonstrates that a yet undetermined role of trophoblast efflux transporters is the elimination of sulfate conjugates.
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Affiliation(s)
- Pallabi Mitra
- Department of Pharmaceutical Chemistry, School of Pharmacy, The University of Kansas, Lawrence, KS 66047, USA
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133
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Paturi DK, Kwatra D, Ananthula HK, Pal D, Mitra AK. Identification and functional characterization of breast cancer resistance protein in human bronchial epithelial cells (Calu-3). Int J Pharm 2009; 384:32-8. [PMID: 19782742 DOI: 10.1016/j.ijpharm.2009.09.037] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2009] [Revised: 09/12/2009] [Accepted: 09/18/2009] [Indexed: 01/16/2023]
Abstract
Breast cancer resistance protein (BCRP), a 72 kDa protein belongs to the subfamily G of the human ATP-binding cassette transporter superfamily. Overexpression of BCRP was found to play a major role in the development of resistance against various chemotherapeutic agents. BCRP plays an important role in absorption, distribution and elimination of several therapeutic agents. BCRP expression and functional activity across human bronchial epithelium and its impact on pulmonary drug accumulation has not been established. The objective of this study was to identify and characterize the BCRP efflux transporter across human bronchial epithelium. Calu-3, a human bronchial epithelial cell line was employed as a model for this study. Reverse transcription-polymerase chain reaction (RT-PCR), Western blot and immunocytochemical studies were performed to identify and characterize the expression of BCRP. RT-PCR studies detected ABCG2 mRNA levels in Calu-3 cells. A strong band for BCRP with a molecular weight of approximately 72 kDa was observed in Western blot analysis. Immunocytochemical studies confirmed the presence of BCRP on the apical membrane of human bronchial epithelium. Functional activity of BCRP was determined by performing uptake of radioactive substrate [3H]-mitoxantrone in the presence and absence of BCRP inhibitors. Uptake of [3H]-mitoxantrone was elevated significantly in the presence of GF120918 and fumitremorgin C. An increase in the accumulation of Hoechst 33342, a fluorescent dye was also detected in the presence of BCRP inhibitors when compared to control. In summary, this study provides evidence for the presence of an ATP dependent, membrane bound efflux transporter BCRP across human bronchial epithelial cell line, Calu-3.
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Affiliation(s)
- Durga Kalyani Paturi
- University of Missouri-Kansas City, School of Pharmacy, 2464 Charlotte street, Kansas City, MO 64108-2718, USA
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134
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Chen X, Sun C, Chen Q, O'Neill FA, Walsh D, Fanous AH, Chowdari KV, Nimgaonkar VL, Scott A, Schwab SG, Wildenauer DB, Che R, Tang W, Shi Y, He L, Luo XJ, Su B, Edwards TL, Zhao Z, Kendler KS. Apoptotic engulfment pathway and schizophrenia. PLoS One 2009; 4:e6875. [PMID: 19721717 PMCID: PMC2731162 DOI: 10.1371/journal.pone.0006875] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Accepted: 07/14/2009] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Apoptosis has been speculated to be involved in schizophrenia. In a previously study, we reported the association of the MEGF10 gene with the disease. In this study, we followed the apoptotic engulfment pathway involving the MEGF10, GULP1, ABCA1 and ABCA7 genes and tested their association with the disease. METHODOLOGY/PRINCIPAL FINDINGS Ten, eleven and five SNPs were genotyped in the GULP1, ABCA1 and ABCA7 genes respectively for the ISHDSF and ICCSS samples. In all 3 genes, we observed nominally significant associations. Rs2004888 at GULP1 was significant in both ISHDSF and ICCSS samples (p = 0.0083 and 0.0437 respectively). We sought replication in independent samples for this marker and found highly significant association (p = 0.0003) in 3 Caucasian replication samples. But it was not significant in the 2 Chinese replication samples. In addition, we found a significant 2-marker (rs2242436 * rs3858075) interaction between the ABCA1 and ABCA7 genes in the ISHDSF sample (p = 0.0022) and a 3-marker interaction (rs246896 * rs4522565 * rs3858075) amongst the MEGF10, GULP1 and ABCA1 genes in the ICCSS sample (p = 0.0120). Rs3858075 in the ABCA1 gene was involved in both 2- and 3-marker interactions in the two samples. CONCLUSIONS/SIGNIFICANCE From these data, we concluded that the GULP1 gene and the apoptotic engulfment pathway are involved in schizophrenia in subjects of European ancestry and multiple genes in the pathway may interactively increase the risks to the disease.
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Affiliation(s)
- Xiangning Chen
- Department of Psychiatry and Virginia Institute for Psychiatric and Behavior Genetics, Virginia Commonwealth University, Richmond, Virginia, USA.
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135
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Abstract
Recent progress in basic research has enhanced our understanding of the molecular mechanisms of normal bile secretion and their alterations in cholestasis. Genetic transporter variants contribute to an entire spectrum of cholestatic liver diseases and can cause hereditary cholestatic syndromes or determine susceptibility and disease progression in acquired cholestatic disorders. Cholestasis is associated with complex transcriptional and post-transcriptional alterations of hepatobiliary transporters and enzymes participating in bile formation. Ligand-activated nuclear receptors for bile acids and other biliary compounds play a key role in the regulation of genes required for bile formation. Pharmacological interventions in cholestasis may aim at modulating such novel regulatory pathways. This review will summarize the principles of molecular alterations in cholestasis and will give an overview of potential clinical implications.
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Affiliation(s)
- Martin Wagner
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Laboratory of Experimental and Molecular Hepatology, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria
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136
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Colicchio R, Ricci S, Lamberti F, Pagliarulo C, Pagliuca C, Braione V, Braccini T, Talà A, Montanaro D, Tripodi S, Cintorino M, Troncone G, Bucci C, Pozzi G, Bruni CB, Alifano P, Salvatore P. The meningococcal ABC-Type L-glutamate transporter GltT is necessary for the development of experimental meningitis in mice. Infect Immun 2009; 77:3578-87. [PMID: 19528209 PMCID: PMC2737999 DOI: 10.1128/iai.01424-08] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 01/21/2009] [Accepted: 06/05/2009] [Indexed: 11/20/2022] Open
Abstract
Experimental animal models of bacterial meningitis are useful to study the host-pathogen interactions occurring at the cerebral level and to analyze the pathogenetic mechanisms behind this life-threatening disease. In this study, we have developed a mouse model of meningococcal meningitis based on the intracisternal inoculation of bacteria. Experiments were performed with mouse-passaged serogroup C Neisseria meningitidis. Survival and clinical parameters of infected mice and microbiological and histological analysis of the brain demonstrated the establishment of meningitis with features comparable to those of the disease in humans. When using low bacterial inocula, meningococcal replication in the brain was very efficient, with a 1,000-fold increase of viable counts in 18 h. Meningococci were also found in the blood, spleens, and livers of infected mice, and bacterial loads in different organs were dependent on the infectious dose. As glutamate uptake from the host has been implicated in meningococcal virulence, mice were infected intracisternally with an isogenic strain deficient in the ABC-type L-glutamate transporter GltT. Noticeably, the mutant was attenuated in virulence in mixed infections, indicating that wild-type bacteria outcompeted the GltT-deficient meningococci. The data show that the GltT transporter plays a role in meningitis and concomitant systemic infection, suggesting that meningococci may use L-glutamate as a nutrient source and as a precursor to synthesize the antioxidant glutathione.
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137
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Abstract
ATP hydrolysis by the maltose transporter (MalFGK(2)) is regulated by maltose binding protein (MBP). Binding of maltose to MBP brings about a conformational change from open to closed that leads to a strong stimulation of the MalFGK(2) ATPase. In this study, we address the long-standing but enigmatic observation that unliganded MBP is also able to stimulate MalFGK(2). Although the mechanism of this stimulation is not understood, it is sometimes attributed to a small amount of closed (but unliganded) MBP that may exist in solution. To gain insight into how MBP regulates the MalFGK(2) ATPase, we have investigated whether the open or the closed conformation of MBP is responsible for MalFGK(2) stimulation in the absence of maltose. The effect of MBP concentration on the stimulation of MalFGK(2) was assessed: for unliganded MBP, the apparent K(M) for stimulation of MalFGK(2) was below 1 microM, while for maltose-bound MBP, the K(M) was approximately 15 microM. We show that engineered MBP molecules in which the open-closed equilibrium has been shifted toward the closed conformation have a decreased ability to stimulate MalFGK(2). These results indicate that stimulation of the MalFGK(2) ATPase by unliganded MBP does not proceed through a closed conformation and instead must operate through a different mechanism than stimulation by liganded MBP. One possible explanation is that the open conformation is able to activate the MalFGK(2) ATPase directly.
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Affiliation(s)
| | | | - Brian H. Shilton
- Department of Biochemistry, The University of Western Ontario, 1151 Richmond St., London, Ontario Canada N6A 5C1
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138
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Klappe K, Hummel I, Hoekstra D, Kok JW. Lipid dependence of ABC transporter localization and function. Chem Phys Lipids 2009; 161:57-64. [PMID: 19651114 DOI: 10.1016/j.chemphyslip.2009.07.004] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 06/24/2009] [Accepted: 07/24/2009] [Indexed: 02/06/2023]
Abstract
Lipid rafts have been implicated in many cellular functions, including protein and lipid transport and signal transduction. ATP-binding cassette (ABC) transporters have also been localized in these membrane domains. In this review the evidence for this specific localization will be evaluated and discussed in terms of relevance to ABC transporter function. We will focus on three ABC transporters of the A, B and C subfamily, respectively. Two of these transporters are relevant to multidrug resistance in tumor cells (Pgp/ABCB1 and MRP1/ABCC1), while the third (ABCA1) is extensively studied in relation to the reverse cholesterol pathway and cellular cholesterol homeostasis. We will attempt to derive a generalized model of lipid rafts to which they associate based on the use of various different lipid raft isolation procedures. In the context of lipid rafts, modulation of ABC transporter localization and function by two relevant lipid classes, i.e. sphingolipids and cholesterol, will be discussed.
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Affiliation(s)
- Karin Klappe
- Department of Cell Biology, Section Membrane Cell Biology, University Medical Center Groningen, University of Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands
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139
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Abstract
Multidrug resistance, cross-resistance to structurally and functionally unrelated drugs, is an important cause of treatment failure in acute leukemia. Multidrug resistance can result from the overexpression of ATP-dependent efflux pumps, such as P-glycoprotein and members of the multidrug resistance associated protein (MRP) family. Recently a novel transporter has been identified, which is called breast cancer resistance protein (BCRP), ABCG2 or mitoxantrone resistance protein. BCRP confers resistance to chemotherapeutic agents, such as mitoxantrone, doxorubicin and daunorubicin. This review describes BCRP detection techniques and the normal physiology of BCRP. The role of BCRP in the physiology of hematopoietic stem cells is addressed as well as the involvement of BCRP in multidrug resistance in acute leukemia. In AML and ALL, several studies showed that BCRP is expressed and functionally active at low, but variable levels. However, further studies are warranted to investigate its effect on clinical outcome, and explore whether patients could benefit from the combination of BCRP inhibitors and chemotherapy.
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Affiliation(s)
- Sabine L A Plasschaert
- Division of Paediatric Oncology and Haematology, University Hospital Groningen, Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
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140
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Shen J, Carcaboso AM, Hubbard KE, Tagen M, Wynn HG, Panetta JC, Waters CM, Elmeliegy MA, Stewart CF. Compartment-specific roles of ATP-binding cassette transporters define differential topotecan distribution in brain parenchyma and cerebrospinal fluid. Cancer Res 2009; 69:5885-92. [PMID: 19567673 PMCID: PMC2729173 DOI: 10.1158/0008-5472.can-09-0700] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Topotecan is a substrate of the ATP-binding cassette transporters P-glycoprotein (P-gp/MDR1) and breast cancer resistance protein (BCRP). To define the role of these transporters in topotecan penetration into the ventricular cerebrospinal fluid (vCSF) and brain parenchymal extracellular fluid (ECF) compartments, we performed intracerebral microdialysis on transporter-deficient mice after an intravenous dose of topotecan (4 mg/kg). vCSF penetration of unbound topotecan lactone was measured as the ratio of vCSF-to-plasma area under the concentration-time curves. The mean +/- SD ratios for wild-type, Mdr1a/b(-/-), Bcrp1(-/-), and Mdr1a/b(-/-)Bcrp1(-/-) mice were 3.07 +/- 0.09, 2.57 +/- 0.17, 1.63 +/- 0.12, and 0.86 +/- 0.05, respectively. In contrast, the ECF-to-plasma ratios for wild-type, Bcrp1(-/-), and Mdr1a/b(-/-)Bcrp1(-/-) mice were 0.36 +/- 0.06, 0.42 +/- 0.06, and 0.88 +/- 0.07. Topotecan lactone was below detectable limits in the ECF of Mdr1a/b(-/-) mice. When gefitinib (200 mg/kg) was preadministered to inhibit Bcrp1 and P-gp, the vCSF-to-plasma ratio decreased to 1.29 +/- 0.09 in wild-type mice and increased to 1.13 +/- 0.13 in Mdr1a/b(-/-)Bcrp1(-/-) mice, whereas the ECF-to-plasma ratio increased to 0.74 +/- 0.14 in wild-type and 1.07 +/- 0.03 in Mdr1a/b(-/-)Bcrp1(-/-) mice. Preferential active transport of topotecan lactone over topotecan carboxylate was shown in vivo by vCSF lactone-to-carboxylate area under the curve ratios for wild-type, Mdr1a/b(-/-), Bcrp1(-/-), and Mdr1a/b(-/-)Bcrp1(-/-) mice of 5.69 +/- 0.83, 3.85 +/- 0.64, 3.61 +/- 0.46, and 0.78 +/- 0.19, respectively. Our results suggest that Bcrp1 and P-gp transport topotecan into vCSF and out of brain parenchyma through the blood-brain barrier. These findings may help to improve pharmacologic strategies to treat brain tumors.
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Affiliation(s)
- Jun Shen
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
- University of Tennessee Health Science Center, University of Tennessee, Memphis
| | - Angel M. Carcaboso
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
| | - K. Elaine Hubbard
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
| | - Michael Tagen
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
| | - Henry G. Wynn
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
| | - John C. Panetta
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
| | | | - Mohamed A. Elmeliegy
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
- University of Tennessee Health Science Center, University of Tennessee, Memphis
| | - Clinton F. Stewart
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
- University of Tennessee Health Science Center, University of Tennessee, Memphis
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141
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Abstract
Trypanosomes contain unique peroxisome-like organelles designated glycosomes which sequester enzymes involved in a variety of metabolic processes including glycolysis. We identified three ABC transporters associated with the glycosomal membrane of Trypanosoma brucei. They were designated GAT1-3 for Glycosomal ABC Transporters. These polypeptides are so-called half-ABC transporters containing only one transmembrane domain and a single nucleotide-binding domain, like their homologues of mammalian and yeast peroxisomes. The glycosomal localization was shown by immunofluorescence microscopy of trypanosomes expressing fusion constructs of the transporters with Green Fluorescent Protein. By expression of fluorescent deletion constructs, the glycosome-targeting determinant of two transporters was mapped to different fragments of their respective primary structures. Interestingly, these fragments share a short sequence motif and contain adjacent to it one--but not the same--of the predicted six transmembrane segments of the transmembrane domain. We also identified the T. brucei homologue of peroxin PEX19, which is considered to act as a chaperonin and/or receptor for cytosolically synthesized proteins destined for insertion into the peroxisomal membrane. By using a bacterial two-hybrid system, it was shown that glycosomal ABC transporter fragments containing an organelle-targeting determinant can interact with both the trypanosomatid and human PEX19, despite their low overall sequence identity. Mutated forms of human PEX19 that lost interaction with human peroxisomal membrane proteins also did not bind anymore to the T. brucei glycosomal transporter. Moreover, fragments of the glycosomal transporter were targeted to the peroxisomal membrane when expressed in mammalian cells. Together these results indicate evolutionary conservation of the glycosomal/peroxisomal membrane protein import mechanism.
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Affiliation(s)
- Cédric Yernaux
- Research Unit for Tropical Diseases, Christian de Duve Institute of Cellular Pathology and Laboratory of Biochemistry, Université catholique de Louvain, Brussels, Belgium
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142
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Abstract
The ATP binding cassette (ABC) transporter Atm1p of the mitochondrial inner membrane performs crucial roles in both the biogenesis of cytosolic/nuclear iron-sulfur proteins and cellular iron homeostasis. Since the function of the mitochondrial iron-sulfur cluster (ISC) assembly machinery is also required for these two processes, Atm1p is thought to translocate a still unknown product of this pathway to the cytosol. Here, we provide a detailed in vitro characterization of Atm1p in order to better understand its function. Atm1p was purified using an expression system in E. coli. The detergent-solubilised protein exhibits a stable ATPase activity. Reconstitution of Atm1p into proteoliposomes allowed us to determine the biochemical characteristics of the ATPase such as: (i) the strong inhibition by the transition state analogue vanadate, (ii) a Km value of 0.1 mM, and (iii) a turnover number of 127 min-1. The ATPase activity of ABC transporters is generally stimulated by their specific substrate. We used this property to define the chemical properties of the substrate transported by Atm1p. ATPase hydrolysis by Atm1p-containing proteoliposomes was specifically increased 3-5-fold by thiol-containing compounds, in particular by micromolar concentrations of cysteine thiol groups in peptides, even though Atm1p is not a general peptide transporter such as yeast Mdl1p or mammalian TAP which share sequence similarity with Atm1p. We speculate that the physiological substrate of Atm1p may contain multiple sulfhydryl groups in a peptidic environment.
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Affiliation(s)
- Grit Kuhnke
- Institut für Zytobiologie und Zytopathologie der Philipps-Universität Marburg, Marburg, Germany
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143
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Strader LC, Bartel B. The Arabidopsis PLEIOTROPIC DRUG RESISTANCE8/ABCG36 ATP binding cassette transporter modulates sensitivity to the auxin precursor indole-3-butyric acid. Plant Cell 2009; 21:1992-2007. [PMID: 19648296 PMCID: PMC2729616 DOI: 10.1105/tpc.109.065821] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 06/27/2009] [Accepted: 07/14/2009] [Indexed: 05/18/2023]
Abstract
Plants have developed numerous mechanisms to store hormones in inactive but readily available states, enabling rapid responses to environmental changes. The phytohormone auxin has a number of storage precursors, including indole-3-butyric acid (IBA), which is apparently shortened to active indole-3-acetic acid (IAA) in peroxisomes by a process similar to fatty acid beta-oxidation. Whereas metabolism of auxin precursors is beginning to be understood, the biological significance of the various precursors is virtually unknown. We identified an Arabidopsis thaliana mutant that specifically restores IBA, but not IAA, responsiveness to auxin signaling mutants. This mutant is defective in PLEIOTROPIC DRUG RESISTANCE8 (PDR8)/PENETRATION3/ABCG36, a plasma membrane-localized ATP binding cassette transporter that has established roles in pathogen responses and cadmium transport. We found that pdr8 mutants display defects in efflux of the auxin precursor IBA and developmental defects in root hair and cotyledon expansion that reveal previously unknown roles for IBA-derived IAA in plant growth and development. Our results are consistent with the possibility that limiting accumulation of the IAA precursor IBA via PDR8-promoted efflux contributes to auxin homeostasis.
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Affiliation(s)
- Lucia C Strader
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA
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144
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Liu XH, Tang CK. [The research progress of ATP binding cassette transporter G1]. Sheng Li Ke Xue Jin Zhan 2009; 40:229-233. [PMID: 19803427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
ATP binding cassette transporter G1 (ABCG1) is a membrane half-transporter which is the member of ATP-binding cassette (ABC) transporter super-family, it has an important role of regulating the cholesterol and phospholipids effluence. ABCG1 and ABCA1 synergize to mediate cholesterol effluence to HDL (high density lipoprotein). The expression of ABCG1 is mainly regulated by the liver X receptor/the lactochrome receptor system (LXR/RXR). Although the ABCG1 plays an important role in balancing the lipids, its role in cardiovascular disease (CVD) in the animal studies is still controversial. The issue focuses the ABCG1 on the structure, the function, the regulation and the contribution to CVD.
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Affiliation(s)
- Xie-Hong Liu
- Institute of Cardiovascular Disease, University of South China, Hengyang 421001, China
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145
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Tarr PT, Tarling EJ, Bojanic DD, Edwards PA, Baldán Á. Emerging new paradigms for ABCG transporters. Biochim Biophys Acta 2009; 1791:584-93. [PMID: 19416657 PMCID: PMC2698934 DOI: 10.1016/j.bbalip.2009.01.007] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 01/13/2009] [Accepted: 01/13/2009] [Indexed: 12/14/2022]
Abstract
Every cell is separated from its external environment by a lipid membrane. Survival depends on the regulated and selective transport of nutrients, waste products and regulatory molecules across these membranes, a process that is often mediated by integral membrane proteins. The largest and most diverse of these membrane transport systems is the ATP binding cassette (ABC) family of membrane transport proteins. The ABC family is a large evolutionary conserved family of transmembrane proteins (>250 members) present in all phyla, from bacteria to Homo sapiens, which require energy in the form of ATP hydrolysis to transport substrates against concentration gradients. In prokaryotes the majority of ABC transporters are involved in the transport of nutrients and other macromolecules into the cell. In eukaryotes, with the exception of the cystic fibrosis transmembrane conductance regulator (CFTR/ABCC7), ABC transporters mobilize substrates from the cytoplasm out of the cell or into specific intracellular organelles. This review focuses on the members of the ABCG subfamily of transporters, which are conserved through evolution in multiple taxa. As discussed below, these proteins participate in multiple cellular homeostatic processes, and functional mutations in some of them have clinical relevance in humans.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily G
- ATP Binding Cassette Transporter, Subfamily G, Member 1
- ATP Binding Cassette Transporter, Subfamily G, Member 2
- ATP Binding Cassette Transporter, Subfamily G, Member 5
- ATP Binding Cassette Transporter, Subfamily G, Member 8
- ATP-Binding Cassette Transporters/classification
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- ATP-Binding Cassette Transporters/physiology
- Animals
- Biological Transport
- Lipoproteins/genetics
- Lipoproteins/metabolism
- Lipoproteins/physiology
- Mice
- Mice, Knockout
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Affiliation(s)
- Paul T. Tarr
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA
| | - Elizabeth J. Tarling
- Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Dragana D. Bojanic
- Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Peter A. Edwards
- Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Molecular Biology Institute, UCLA, Los Angeles, CA 90095, USA
| | - Ángel Baldán
- Edward A. Doisy Department of Biochemistry and Molecular Biology, DRC 321, Saint Louis University School of Medicine, 1100 S. Grand Blvd., St. Louis, MO 63104, USA
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146
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Abstract
PURPOSE OF REVIEW Generation of bile is an important function of the liver. Its impairment can be caused by inherited mutations or by acquired factors and leads to cholestasis. Bile salts are an important constituent of bile and are secreted by the bile salt export pump (BSEP) from hepatocytes. RECENT FINDINGS Significant progress was made in the understanding of mechanisms and consequences of malfunctioning BSEP. This information was gained from extensive characterization of patients with inherited BSEP deficiency and the subsequent characterization of the identified mutations in heterologous expression systems. Furthermore and importantly, clinical evidence shows that patients with severe BSEP deficiency are at risk to develop hepatocellular carcinoma. Bile salts are now recognized to be important in the modulation of whole body energy homeostasis. Because BSEP is the rate-limiting step in hepatocellular bile salt transport, it controls the spill over of bile salts into the systemic circulation. Therefore, an indirect role of BSEP in energy homeostasis becomes more and more likely. SUMMARY In summary, knowledge on the physiologic and pathophysiologic role of BSEP is rapidly progressing. It can be anticipated that the next major step in better understanding BSEP should come from information on structure-function relationship. However, given the difficulty in structure determination of mammalian transporters, this will require major efforts.
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Affiliation(s)
- Bruno Stieger
- Division of Clinical Pharmacology and Toxicology, Department of Medicine, University Hospital, Zurich, Switzerland.
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147
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Zhang RY, Jin HF, Tang CS, DU JB. [ATP-sensitive potassium channel and its cardiovascular protection effects]. Beijing Da Xue Xue Bao Yi Xue Ban 2009; 41:245-248. [PMID: 19377640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
ATP-sensitive potassium channel(K(ATP)) consists of a 4.4 complex of an inwardly rectifying Kir6.x pore plus a sulfonylurea receptor, which is an ATP-binding cassette transporter. K(ATP) has been indentified in a variety of tissues and recognized as an important drug target. It connects cell metabolism with cell electric activity. K(ATP) has been proposed to play protective roles during heart failure, arrhythmia, myocardial infarction, stress, myocardial ischemia and hypertension. In this review, a summary of K(ATP) is presented with molecular structure, localization, regulation, cardiovascular protective effect and its mechanisms.
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Affiliation(s)
- Rong-yuan Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
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148
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Huang CF, Yamaji N, Mitani N, Yano M, Nagamura Y, Ma JF. A bacterial-type ABC transporter is involved in aluminum tolerance in rice. Plant Cell 2009; 21:655-67. [PMID: 19244140 PMCID: PMC2660611 DOI: 10.1105/tpc.108.064543] [Citation(s) in RCA: 248] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 01/06/2009] [Accepted: 02/12/2009] [Indexed: 05/18/2023]
Abstract
Aluminum (Al) toxicity is a major factor limiting crop production in acidic soil, but the molecular mechanisms of Al tolerance are poorly understood. Here, we report that two genes, STAR1 (for sensitive to Al rhizotoxicity1) and STAR2, are responsible for Al tolerance in rice. STAR1 encodes a nucleotide binding domain, while STAR2 encodes a transmembrane domain, of a bacterial-type ATP binding cassette (ABC) transporter. Disruption of either gene resulted in hypersensitivity to aluminum toxicity. Both STAR1 and STAR2 are expressed mainly in the roots and are specifically induced by Al exposure. Expression in onion epidermal cells, rice protoplasts, and yeast showed that STAR1 interacts with STAR2 to form a complex that localizes to the vesicle membranes of all root cells, except for those in the epidermal layer of the mature zone. When expressed together in Xenopus laevis oocytes, STAR1/2 shows efflux transport activity specific for UDP-glucose. Furthermore, addition of exogenous UDP-glucose rescued root growth in the star1 mutant exposed to Al. These results indicate that STAR1 and STAR2 form a complex that functions as an ABC transporter, which is required for detoxification of Al in rice. The ABC transporter transports UDP-glucose, which may be used to modify the cell wall.
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Affiliation(s)
- Chao Feng Huang
- Research Institute for Bioresources, Okayama University, Kurashiki 710-0046, Japan
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149
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Abstract
ABCG2 is best known as a multidrug transporter capable of conferring resistance to cancer cells. However, the protein is also inherently expressed in numerous barrier tissues and intriguingly within hematopoietic stem cells. Unlike its partners ABCB1 and ABCC1, there is considerably less information available on the molecular mechanism of ABCG2. The transporter has a distinct topology and is presumed to function as a homodimer. However, a number of biochemical studies have presented data to suggest that the protein adopts higher order oligomers. This review focuses on this controversial issue with particular reference to findings from low resolution structural data. In addition, a number of molecular models of ABCG2 based on high resolution structures of bacterial ABC transporters have recently become available and are critically assessed. ABCG2 is a structurally distinct member of the triumvirate of human multidrug transporters and continues to evade description of a unifying molecular mechanism.
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Affiliation(s)
- Christopher A McDevitt
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, United Kingdom
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150
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Nicolle E, Boumendjel A, Macalou S, Genoux E, Ahmed-Belkacem A, Carrupt PA, Di Pietro A. QSAR analysis and molecular modeling of ABCG2-specific inhibitors. Adv Drug Deliv Rev 2009; 61:34-46. [PMID: 19135106 DOI: 10.1016/j.addr.2008.10.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Accepted: 10/01/2008] [Indexed: 01/27/2023]
Abstract
In addition to its critical role is controlling drug availability and protecting sensitive organs and stem cells through cellular detoxification, breast cancer resistance protein (BCRP/ABCG2) plays an important role in cancer cell resistance to chemotherapy, together with P-glycoprotein/ABCB1. A main approach to abolish multidrug resistance is to find out specific inhibitors of the drug-efflux activity, able to chemosensitize cancer cell proliferation. Many efforts have been primarily focused on ABCB1, discovered thirty years ago, whereas very few studies have concerned ABCG2, identified much more recently. This review describes the main types of inhibitors presently known for ABCG2, and how quantitative structure-activity relationship analysis among series of compounds may lead to build up molecular models and pharmacophores allowing to design lead inhibitors as future candidates for clinical trials. A special attention is drawn on flavonoids which constitute a structurally-diverse class of compounds, well suited to identify potent ABCG2-specific inhibitors.
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Affiliation(s)
- E Nicolle
- Département de Pharmacochimie Moléculaire, UMR 5063. ICMG-FR 2607-Université Joseph Fourier Grenoble I, 470 rue de la Chimie, 38240 St Martin d'Hères, France
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