scholarly journals Podocyte-specific expression of organic cation transporter PMAT: implication in puromycin aminonucleoside nephrotoxicity

2009 ◽  
Vol 296 (6) ◽  
pp. F1307-F1313 ◽  
Author(s):  
Li Xia ◽  
Mingyan Zhou ◽  
Thomas F. Kalhorn ◽  
Horace T. B. Ho ◽  
Joanne Wang
Keyword(s):  
Cellular Localization ◽  
Organic Cation ◽  
Kidney Injury ◽  
Organic Cation Transporter ◽  
Intracellular Loop ◽  
Puromycin Aminonucleoside ◽  
Specific Expression ◽  
Specific Localization ◽  
Immunofluorescence Labeling ◽  
And Function

Plasma membrane monoamine transporter (PMAT) is a novel polyspecific organic cation transporter that transports organic cations and the purine nucleoside, adenosine. PMAT is expressed in the kidney, but the specific localization and function of this transporter in renal cells are unclear. In this study, we developed a polyclonal antibody toward a 14-amino acid sequence in the last intracellular loop of PMAT and determined the precise cellular localization of PMAT in human and rat kidneys. Surprisingly, we found that the PMAT protein was predominantly expressed in the glomerulus with minimal expression in tubular cells. Within the glomerulus, dual-color immunofluorescence labeling showed that the PMAT protein was specifically localized to the visceral glomerular epithelial cells, i.e., podocytes. There was no significant PMAT immunoreactivity in mesangial or glomerular endothelial cells. We further showed that puromycin aminonucleoside (PAN), a classic podocyte toxin that induces massive proteinuria and severe glomerulopathy, is transported by PMAT. Expression of PMAT in Madin-Darby canine kidney cells significantly increased cell sensitivity to PAN. Decynium 22, a potent PMAT inhibitor, abolished PAN toxicity in PMAT-expressing cells. Together, our data suggest that PMAT is specifically expressed in podocytes and may play an important role in PAN-induced kidney injury.

scholarly journals Stage-specific Localization and Expression of c-kit in the Adult Human Testis

2009 ◽  
Vol 57 (9) ◽  
pp. 861-869 ◽  
Author(s):  
Sreepoorna K. Unni ◽  
Deepak N. Modi ◽  
Shilpa G. Pathak ◽  
Jayesh V. Dhabalia ◽  
Deepa Bhartiya
Keyword(s):  
Current Knowledge ◽  
Protein Localization ◽  
Immunohistochemical Analysis ◽  
Human Testis ◽  
Specific Expression ◽  
Adult Human ◽  
Kit Receptor ◽  
Specific Localization ◽  
Human Spermatogenesis ◽  
And Function

The c-kit receptor (KIT) and its ligand, stem cell factor (SCF), represent one of the key regulators of testicular formation, development, and function and have been extensively studied in various animal models. The present study was undertaken to characterize the pattern of localization and expression of c-kit in normal adult human testis. Immunohistochemical analysis showed that KIT is expressed in the cytoplasm of spermatogonia, acrosomal granules of spermatids, and Leydig cells. Interestingly, a rather heterogenous pattern of expression of the protein along the basement membrane was observed. Intense protein localization in spermatogonia was detected in stages I–III, whereas low expression was observed in stages IV–VI of the seminiferous epithelium, indicating that the expression of the molecule was stage specific. In situ hybridization studies revealed that the transcripts of the gene were also localized in a similar non-uniform pattern. To the best of our knowledge, such a stage-specific expression of KIT has not been reported previously in the human testis. The results of the present study may expand current knowledge about the c-kit/SCF system in human spermatogenesis.

Wedelolactone protects against cisplatin-induced nephrotoxicity in mice via inhibition of organic cation transporter 2

2021 ◽  
pp. 096032712110479
Author(s):  
Guangju Wang ◽  
Yajuan Bi ◽  
Hui Xiong ◽  
Tongwei Bo ◽  
Lifeng Han ◽  
...  
Keyword(s):  
Natural Compound ◽  
Organic Cation ◽  
Kidney Injury ◽  
Organic Cation Transporter ◽  
Competitive Inhibitor ◽  
Hek293 Cells ◽  
Cytotoxicity Studies ◽  
Organic Cation Transporter 2 ◽  
Uptake Assay ◽  
Noncompetitive Inhibitor

The balance of cisplatin uptake and efflux, mediated mainly by organic cation transporter 2 (OCT2) and multidrug and toxin extrusion 1 (MATE1), respectively, determines the renal accumulation and nephrotoxicity of cisplatin. Using transporter-mediated cellular uptake assay, we identified wedelolactone (WEL), a medicinal plant-derived natural compound, is a competitive inhibitor of OCT2 and a noncompetitive inhibitor of MATE1. Wedelolactone showed a selectivity to inhibit OCT2 rather than MATE1. Cytotoxicity studies revealed that wedelolactone alleviated cisplatin-induced cytotoxicity in OCT2-overexpressing HEK293 cells, whereas it did not alter the cytotoxicity of cisplatin in various cancer cell lines. Additionally, wedelolactone altered cisplatin pharmacokinetics, reduced kidney accumulation of cisplatin, and ameliorated cisplatin-induced acute kidney injury in the Institute of Cancer Research mice. In conclusion, these findings suggest a translational potential of WEL as a natural therapy for preventing cisplatin-induced nephrotoxicity and highlight the need for drug–drug interaction investigations of WEL with other treatments which are substrates of OCT2 and/or MATE1.

scholarly journals Regulation Mechanisms of Expression and Function of Organic Cation Transporter 1

2021 ◽  
Vol 11 ◽  
Author(s):  
Giuliano Ciarimboli
Keyword(s):  
Organic Cation ◽  
Basolateral Membrane ◽  
Organic Cation Transporter ◽  
Organic Cations ◽  
Regulatory Processes ◽  
Organic Cation Transporter 1 ◽  
Exogenous Origin ◽  
And Function

The organic cation transporter 1 (OCT1) belongs together with OCT2 and OCT3 to the solute carrier family 22 (SLC22). OCTs are involved in the movement of organic cations through the plasma membrane. In humans, OCT1 is mainly expressed in the sinusoidal membrane of hepatocytes, while in rodents, OCT1 is strongly represented also in the basolateral membrane of renal proximal tubule cells. Considering that organic cations of endogenous origin are important neurotransmitters and that those of exogenous origin are important drugs, these transporters have significant physiological and pharmacological implications. Because of the high expression of OCTs in excretory organs, their activity has the potential to significantly impact not only local but also systemic concentration of their substrates. Even though many aspects governing OCT function, interaction with substrates, and pharmacological role have been extensively investigated, less is known about regulation of OCTs. Possible mechanisms of regulation include genetic and epigenetic modifications, rapid regulation processes induced by kinases, regulation caused by protein–protein interaction, and long-term regulation induced by specific metabolic and pathological situations. In this mini-review, the known regulatory processes of OCT1 expression and function obtained from in vitro and in vivo studies are summarized. Further research should be addressed to integrate this knowledge to known aspects of OCT1 physiology and pharmacology.

Kidney-specific expression of human organic cation transporter 2 (OCT2/SLC22A2) is regulated by DNA methylation

2008 ◽  
Vol 295 (1) ◽  
pp. F165-F170 ◽  
Author(s):  
Masayo Aoki ◽  
Tomohiro Terada ◽  
Moto Kajiwara ◽  
Ken Ogasawara ◽  
Iwao Ikai ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Promoter Region ◽  
Organic Cation ◽  
Methylation Status ◽  
Organic Cation Transporter ◽  
Proximal Promoter ◽  
Specific Expression ◽  
Proximal Promoter Region ◽  
E Box ◽  
Organic Cation Transporter 2

Human organic cation transporter 2 (OCT2/SLC22A2), which is specifically expressed in the kidney, plays critical roles in the renal secretion of cationic compounds. Tissue expression and membrane localization of OCT2 are closely related to the tissue distribution, pharmacological effects, and/or adverse effects of its substrate drugs. However, the molecular mechanisms underlying the kidney-specific expression of OCT2 have not been elucidated. In the present study, therefore, we examined the contribution of DNA methylation of the promoter region for the OCT2 gene to its tissue-specific expression using human tissue samples. In vivo methylation status of the proximal promoter region of OCT2 and that of OCT1, a liver-specific organic cation transporter, were investigated by bisulfite sequencing using human genomic DNA extracted from the kidney and liver. All CpG sites in the OCT2 proximal promoter were hypermethylated in the liver, while hypomethylated in the kidney. On the other hand, the promoter region of OCT1 was hypermethylated in both the kidney and liver. The level of methylation of the OCT2 promoter was especially low at the CpG site in the E-box, the binding site of the basal transcription factor upstream stimulating factor (USF) 1. In vitro methylation of the OCT2 proximal promoter dramatically reduced the transcriptional activity, and an electrophoretic mobility shift assay showed that methylation at the E-box inhibited the binding of USF1. These results indicate that kidney-specific expression of human OCT2 is regulated by methylation of the proximal promoter region, interfering with the transactivation by USF1.

scholarly journals Organic Cation Transporter 1 an Intestinal Uptake Transporter: Fact or Fiction?

2021 ◽  
Vol 12 ◽  
Author(s):  
Christoph Wenzel ◽  
Marek Drozdzik ◽  
Stefan Oswald
Keyword(s):  
Cellular Localization ◽  
Organic Cation ◽  
Basolateral Membrane ◽  
Organic Cation Transporter ◽  
Systemic Circulation ◽  
Current Evidence ◽  
Human Intestine ◽  
Intestinal Uptake ◽  
Organic Cation Transporter 1

Intestinal transporter proteins are known to affect the pharmacokinetics and in turn the efficacy and safety of many orally administered drugs in a clinically relevant manner. This knowledge is especially well-established for intestinal ATP-binding cassette transporters such as P-gp and BCRP. In contrast to this, information about intestinal uptake carriers is much more limited although many hydrophilic or ionic drugs are not expected to undergo passive diffusion but probably require specific uptake transporters. A transporter which is controversially discussed with respect to its expression, localization and function in the human intestine is the organic cation transporter 1 (OCT1). This review article provides an up-to-date summary on the available data from expression analysis as well as functional studies in vitro, animal findings and clinical observations. The current evidence suggests that OCT1 is expressed in the human intestine in small amounts (on gene and protein levels), while its cellular localization in the apical or basolateral membrane of the enterocytes remains to be finally defined, but functional data point to a secretory function of the transporter at the basolateral membrane. Thus, OCT1 should not be considered as a classical uptake transporter in the intestine but rather as an intestinal elimination pathway for cationic compounds from the systemic circulation.

scholarly journals Expression and Function of Organic Cation Transporter 2 in Pancreas

2021 ◽  
Vol 9 ◽  
Author(s):  
Sandra Schorn ◽  
Ann-Kristin Dicke ◽  
Ute Neugebauer ◽  
Rita Schröter ◽  
Maren Friedrich ◽  
...  
Keyword(s):  
High Glucose ◽  
Glucose Transporter ◽  
Organic Cation ◽  
Organic Cation Transporter ◽  
Drug Uptake ◽  
Β Cells ◽  
Human Embryonic Kidney Cells ◽  
Glucose Transporter 2 ◽  
Organic Cation Transporter 2 ◽  
And Function

Organic cation transporters (OCT) play an important role in mediating cellular uptake of several pharmaceuticals, such as the antidiabetic drug metformin and the platinum-derived chemotherapeutics. Since these drugs can also affect the pancreas, here it was investigated whether these transporters are expressed in this organ. An interaction between OCT2 and the glucose transporter 2 (GLUT2), which is expressed with important functional consequences in the kidneys and in the pancreas, has already been demonstrated elsewhere. Therefore, here it was further investigated whether the two proteins have a functional relationship. It was demonstrated that OCT2 is expressed in pancreas, probably in β cells of Langerhans islets, together with GLUT2. However, a co-localization was only evident in a cell-line model of rat pancreatic β cells under incubation with high glucose concentration. High glucose stimulated OCT2 expression and activity. On the other side, studies conducted in human embryonic kidney cells stably expressing OCT2, showed that overexpression of GLUT2 decreased OCT2 activity. Unfortunately, pull-down experiments aimed to confirm a physical OCT2/GLUT2 interaction were not successful. Renal glucose excretion was reduced in mice with genetic deletion of OCT2. Nonetheless, in these mice no regulation of known kidney glucose transporters was measured. Therefore, it may be speculated that OCT2 may influence cellular trafficking of GLUT2, without changing its amount. OCT2 may play a role in drug uptake of the pancreas, and its activity may be regulated by glucose and GLUT2. Vice versa, GLUT2 activity may be regulated through an interaction with OCT2.

scholarly journals The Role of NF-kB in the Downregulation of Organic Cation Transporter 2 Expression and Renal Cation Secretion in Kidney Disease

2022 ◽  
Vol 8 ◽  
Author(s):  
Chao Han ◽  
Juan Zheng ◽  
Fengyi Wang ◽  
Qingyang Lu ◽  
Qingfa Chen ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Organic Cation ◽  
Rat Kidney ◽  
Basolateral Membrane ◽  
Kidney Injury ◽  
Organic Cation Transporter ◽  
Tubular Secretion ◽  
Gene Reporter Assay ◽  
Organic Cation Transporter 2

Organic cation transporter 2 (OCT2), encoded by the SLC22A2 gene, is the main cation transporter on the basolateral membrane of proximal tubular cells. OCT2 facilitates the entry step of the vectorial transport of most cations from the peritubular space into the urine. OCT2 downregulation in kidney disease models is apparent, yet not clear from a mechanistic vantage point. The aim of this study was to explore the role of inflammation, a common thread in kidney disease, and NF-kB in OCT2 modulation and tubular secretion. Among the OCTs, OCT2 was found consistently downregulated in the kidney of rats with chronic kidney disease (CKD) or acute kidney injury (AKI) and in patients diagnosed with CKD, and it was associated with the upregulation of TNFα renal expression. Exposure to TNFα reduced the expression and function of OCT2 in primary renal proximal tubule epithelial cells (RPTEC). Silencing or pharmacological inhibition of NF-kB rescued the expression of OCT2 in the presence of TNFα, indicating that OCT2 repression was NF-kB-dependent. In silico prediction coupled to gene reporter assay demonstrated the presence of at least one functional NF-kB cis-element upstream the transcription starting site of the SLC22A2 gene. Acute inflammation triggered by lipopolysaccharide injection induced TNFα expression and the downregulation of OCT2 in rat kidney. The inflammation did reduce the active secretion of the cation Rhodamine 123, with no impairment of the glomerular filtration. In conclusion, the NF-kB pathway plays a major role in the transcriptional regulation of OCT2 and, in turn, in the overall renal secretory capacity.

scholarly journals Kidney-specific expression of a novel mouse organic cation transporter-like protein

FEBS Letters ◽  
1997 ◽  
Vol 417 (3) ◽  
pp. 371-374 ◽  
Author(s):  
Kiyoshi Mori ◽  
Yoshihiro Ogawa ◽  
Ken Ebihara ◽  
Tomohiro Aoki ◽  
Naohisa Tamura ◽  
...  
Keyword(s):  
Organic Cation ◽  
Organic Cation Transporter ◽  
Specific Expression

Localization And Function Of Carnitine/organic Cation Transporter OCTN2 In The Skeletal Muscles

2010 ◽  
Vol 42 ◽  
pp. 567-568
Author(s):  
Yasuro Furuichi ◽  
Tomoko Sugiura ◽  
Yukio Kato ◽  
Yuya Shimada ◽  
Takeshi Hashimoto ◽  
...  
Keyword(s):  
Skeletal Muscles ◽  
Organic Cation ◽  
Organic Cation Transporter ◽  
And Function

scholarly journals Intracellular β1-Adrenergic Receptors and Organic Cation Transporter 3 Mediate Phospholamban Phosphorylation to Enhance Cardiac Contractility

2020 ◽  
Author(s):  
Ying Wang ◽  
Qian Shi ◽  
Minhui Li ◽  
Meimi Zhao ◽  
Gopireddy Raghavender Reddy ◽  
...  
Keyword(s):  
Single Molecule ◽  
Organic Cation ◽  
Cardiac Contractility ◽  
Super Resolution ◽  
Organic Cation Transporter ◽  
Proximity Ligation ◽  
Resolution Imaging ◽  
Organic Cation Transporter 3 ◽  
And Function ◽  
Phospholamban Phosphorylation

Rationale: β 1 -adrenoceptors (β 1 ARs) exist at intracellular membranes and Organic Cation Transporter 3 (OCT3) mediates norepinephrine entry into cardiomyocytes. However, the functional role of intracellular β 1 AR in cardiac contractility remains to be elucidated. Objective: Test localization and function of intracellular β 1 AR on cardiac contractility. Methods and Results: Membrane fractionation, super-resolution imaging, proximity ligation, co-immunoprecipitation and single-molecule pulldown demonstrated a pool of β 1 ARs in mouse hearts that was associated with sarco/endoplasmic reticulum Ca 2+ -ATPase at the sarcoplasmic reticulum (SR). Local protein kinase A (PKA) activation was measured using a PKA biosensor targeted at either the plasma membrane (PM) or SR. Compared to wild type (WT), myocytes lacking OCT3 (OCT3KO) responded identically to the membrane-permeant βAR agonist isoproterenol in PKA activation at both PM and SR. The same was true at the PM for membrane-impermeant norepinephrine, but the SR response to norepinephrine was suppressed in OCT3KO myocytes. This differential effect was recapitulated in phosphorylation of the SR-pump regulator phospholamban. Similarly, OCT3KO selectively suppressed calcium transients and contraction responses to norepinephrine, but not isoproterenol. Furthermore, sotalol, a membrane-impermeant βAR-blocker suppressed isoproterenol-induced PKA activation at the PM, but permitted PKA activation at the SR, phospholamban phosphorylation and contractility. Moreover, pretreatment with sotatol in OCT3KO myocytes prevented norepinephrine induced PKA activation at both PM and the SR and contractility. Conclusions: Functional β 1 ARs exists at the SR and is critical for PKA-mediated phosphorylation of phospholamban and cardiac contractility upon catecholamine stimulation. Activation of these intracellular β 1 ARs requires catecholamine transport via OCT3.

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