The ABCs of solute carriers: physiological, pathological and therapeutic implications of human membrane transport proteins

Hediger, Matthias A.; Romero, Michael F.; Ji, Peng; Rolfs, Andreas; Takanaga, Hitomi; Bruford, Elspeth A.

doi:10.1007/s00424-003-1192-y

Cited by 865 publications

(647 citation statements)

References 23 publications

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“…Alternative splicing in higher eukaryotic organisms enables a single gene to produce different proteins (16). Solute carrier genes by alternative splicing strategies encode for distinct transmembrane transporters that differ in their tissue distribution, subcellular localization, and physiological proprieties, allowing the development of sophisticated transport systems (17). For examples in the field of the renal transporters, the slc14a2 gene encodes five isoforms of urea transporter (UT-A) that differ in the carboxyl or amino terminal domains, and cause differences in the phosphorylation sensitivity after vasopressin stimulation and in tissue distribution (18).…”

Section: Discussionmentioning

confidence: 99%

Cystinosin-LKG rescues cystine accumulation and decreases apoptosis rate in cystinotic proximal tubular epithelial cells

et al. 2016

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Background: Nephropathic cystinosis is a lysosomal storage disease that is caused by mutations in the CTNS gene encoding a cystine/proton symporter cystinosin and an isoform cystinosin-LKG which is generated by an alternative splicing of exon 12. We have investigated the physiological role of the cystinosin-LKG that is widely expressed in epithelial tissues. Methods: We have analyzed the intracellular localization and the function of the cystinosin-LKG conjugated with DsRed (cystinosin-LKG-RFP) in Madin-Darby canine kidney cells (MDCK II) and in proximal tubular epithelial cells carrying a deletion of the CTNS gene (cystinotic PTEC), respectively. results: Cystinosin-LKG-RFP colocalized with markers of lysosomes, late endosomes and was also expressed on the apical surface of polarized MDCK II cells. Moreover, immuneelectron microscopy images of MDCK II cells overexpressing cystinosin-LKG-RFP showed stacked lamellar membranes inside perinuclear lysosomal structures. To study the role of LKG-isoform, we have investigated cystine accumulation and apoptosis that have been described in cystinotic cells. Cystinosin-LKG decreased cystine levels by approximately 10-fold similarly to cystinosin-RFP. The levels of TNFα-and actinomycin D-inducted apoptosis dropped in cystinotic cells expressing LKG-isoform. This effect was also similar to the main isoform. conclusion: Our results suggest that cystinosin-LKG and cystinosin move similar functional activities in cells.n ephropathic cystinosis (NC) is a rare lysosomal storage disease. It is caused by defective activity of cystinosin, a proton/cystine symporter that is ubiquitously expressed on lysosomal membranes, which leads to cystine accumulation into lysosomes and crystal formations in many tissues (1). One of the first symptoms of NC is renal Fanconi syndrome, secondary to a global dysfunction of proximal tubular cells. During their lifetimes, patients with NC develop several others symptoms in particular, if they are not well treated with cysteamine (2,3).Recent works have demonstrated an involvement of cystinosin in lysosomal kinetics and exocytosis (4), vesicle trafficking (4,5), autophagy, (6) and in sensing cell oxidative state (7). Studies using a cystinotic mouse model have shown decreased expression of the multi-ligand receptors megalin and cubilin in proximal tubules; this was associated with cell dedifferentiation and apoptosis (5,8). Also, enhanced cell death due to activation of proapoptotic signals probably occurs in other tissues (9-11).Cystinosin (accession number: NP_004928) is composed of seven transmembrane domains that bear two lysosomal targeting motifs (GYDQL and YFPQA) and seven N-glycosylation sites in the amino-terminal region (12). The aceview database reports various alternative splicing transcripts for the CTNS gene that encodes the cystinosin (http://www.ncbi.nlm.nih. gov/IEB/Research/Acembly). In 2008, we have identified a 400 amino acid cystinosin isoform that derives from alternative splicing of CTNS gene exon 12 (accession number: NP_001026...

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Section: Discussionmentioning

confidence: 99%

Cystinosin-LKG rescues cystine accumulation and decreases apoptosis rate in cystinotic proximal tubular epithelial cells

et al. 2016

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“…447,No. 5) summarising physiological, pathophysiological, and pharmacological implications of each SLC family (Hediger et al 2004). Currently, 43 SLC families are established in which a total of 319 human transporter genes and about the same number of rat and mouse transporter genes have been identified 1 .…”

Section: Introductionmentioning

confidence: 99%

The solute carrier family SLC10: more than a family of bile acid transporters regarding function and phylogenetic relationships

Geyer

Wilke

Petzinger

2006

Naunyn Schmied Arch Pharmacol

161

138

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The solute carrier family 10 (SLC10) comprises two sodium-dependent bile acid transporters, i.e. the Na + / taurocholate cotransporting polypeptide (NTCP; SLC10A1) and the apical sodium-dependent bile acid transporter (ASBT; SLC10A2). These carriers are essentially involved in the maintenance of the enterohepatic circulation of bile acids mediating the first step of active bile acid transport through the membrane barriers in the liver (NTCP) and intestine (ASBT). Recently, four new members of the SLC10 family were described and referred to as P3 (SLC10A3), P4 (SLC10A4), P5 (SLC10A5) and sodium-dependent organic anion transporter (SOAT; SLC10A6). Experimental data supporting carrier function of P3, P4, and P5 is currently not available. However, as demonstrated for SOAT, not all members of the SLC10 family are bile acid transporters. SOAT specifically transports steroid sulfates such as oestrone-3-sulfate and dehydroepiandrosterone sulfate in a sodium-dependent manner, and is considered to play an important role for the cellular delivery of these prohormones in testes, placenta, adrenal gland and probably other peripheral tissues. ASBT and SOAT are the most homologous members of the SLC10 family, with high sequence similarity (∼70%) and almost identical gene structures. Phylogenetic analyses of the SLC10 family revealed that ASBT and SOAT genes emerged from a common ancestor gene. Structure-activity relationships of NTCP, ASBT and SOAT are discussed at the amino acid sequence level.Based on the high structural homology between ASBT and SOAT, pharmacological inhibitors of the ASBT, which are currently being tested in clinical trials for cholesterollowering therapy, should be evaluated for their crossreactivity with SOAT.

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“…5 Their cellular uptake may be mediated by organic cation transporters (OCTs) that belong to the solute carrier family 22 (SLC22). 2,6 In human liver, only OCT1 (SLC22A1) [7][8][9] and OCT3 (SLC22A3) 10,11 transcripts are present, whereas OCT2 is primarily expressed in kidney and neither OCT2 (SLC22A2) messenger RNA (mRNA) 7,12 nor OCT2 protein 13 are detectable in liver. OCT1 is localized in the sinusoidal membrane of rat as well as human hepato-cytes.…”

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confidence: 99%

Expression of Organic Cation Transporters OCT1 (SLC22A1) and OCT3 (SLC22A3) Is Affected by Genetic Factors and Cholestasis in Human Liver†

et al. 2009

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An important function of hepatocytes is the biotransformation and elimination of various drugs, many of which are organic cations and are taken up by organic cation transporters (OCTs) of the solute carrier family 22 (SLC22). Because interindividual variability of OCT expression may affect response to cationic drugs such as metformin, we systematically investigated genetic and nongenetic factors of OCT1/SLC22A1 and OCT3/SLC22A3 expression in human liver. OCT1 and OCT3 expression (messenger RNA [mRNA], protein) was analyzed in liver tissue samples from 150 Caucasian subjects. Hepatic OCTs were localized by way of immunofluorescence microscopy. Matrixassisted laser desorption/ionization time-of-flight mass spectrometry and genome-wide singlenucleotide polymorphism microarray technology served to genotype 92 variants in the SLC22A1-A3/ OCT1-3 gene cluster. Transport of metformin by recombinant human OCT1 and OCT3 was compared using transfected cells. OCT1 mRNA and protein expression varied 113-and 83-fold, respectively; OCT3 mRNA expression varied 27-fold. OCT1 transcript levels were on average 15-fold higher compared with OCT3. We localized the OCT3 protein to the basolateral hepatocyte membrane and identified metformin as an OCT3 substrate. OCT1 and OCT3 expression are independent of age and sex but were significantly reduced in liver donors diagnosed as cholestatic (P < 0.01). Several haplotypes for OCT1 and OCT3 were identified. Multivariate analysis adjusted for multiple testing showed that only the OCT1-Arg61Cys variant (rs12208357) strongly correlated with decreased OCT1 protein expression (P < 0.0001), and four variants in OCT3 (rs2292334, rs2048327, rs1810126, rs3088442) were associated with reduced OCT3 mRNA levels (P ‫؍‬ 0.03). Conclusion: We identified cholestasis and genetic variants as critical determinants for considerable interindividual variability of hepatic OCT1 and OCT3 expression. This indicates consequences for hepatic elimination of and response to OCT substrates such as metformin.

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The ABCs of solute carriers: physiological, pathological and therapeutic implications of human membrane transport proteins

Cited by 865 publications

References 23 publications

Cystinosin-LKG rescues cystine accumulation and decreases apoptosis rate in cystinotic proximal tubular epithelial cells

Cystinosin-LKG rescues cystine accumulation and decreases apoptosis rate in cystinotic proximal tubular epithelial cells

The solute carrier family SLC10: more than a family of bile acid transporters regarding function and phylogenetic relationships

Expression of Organic Cation Transporters OCT1 (SLC22A1) and OCT3 (SLC22A3) Is Affected by Genetic Factors and Cholestasis in Human Liver†

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