Organic cation uptake is enhanced in bcrp1-transfected MDCKII cells.
ABSTRACT Stably transfected cell models are routinely used to examine drug-transporter interactions. In one such model of bcrp1-transfected MDCKII cells, we observed a significant enhancement of organic cation intracellular accumulation. Therefore, our goal was to further explore the expression and functional consequences of this cation transport system. Transport assays were carried out in wild-type and bcrp1-transfected MDCKII cells to examine uptake of [3H]-prazosin (bcrp1 positive control), [3H]-agmatine, [3H]-TEA, and [14C]-choline. RT-PCR was employed to determine the mRNA levels of bcrp1 and OCT2/OCT3. Western blots were used to evaluate corresponding protein levels. Accumulation studies determined a significant increase in the uptake of the organic cations agmatine, TEA, and choline in bcrp1-transfected cells when compared to wild-type cells. Directional transport of [3H]-agmatine showed a significantly greater apical (A) to basolateral (B) than B-to-A flux in both cell types. In spite of this, the A-to-B flux was significantly lower in bcrp1-transfected cells. RT-PCR revealed 10-fold higher OCT2 mRNA levels in bcrp1-transfected cells, with no changes in OCT3. OCT2 protein expression was approximately 3.5-fold higher in bcrp1-transfected cells. The upregulation of OCT2 in bcrp1-transfected MDCKII cells contributed to a significant enhancement in the uptake of several organic cations. These results are consistent with the endogenous expression of OCT2 in the kidney tubule, and may be related to the expression and function of bcrp1. Our findings illustrate the importance of understanding how endogenous transporters, which may compete for common substrates, may be influenced by the overexpression and enhanced function of recombinant transport systems.
Article: Evidence for recombination among the tomato leaf curl virus strains/species from Bangalore, India.[show abstract] [hide abstract]
ABSTRACT: Tomato leaf curl virus (ToLCV) belongs to the Begomovirus genus of the family Geminiviridae. These viruses have circular single stranded DNA molecules as their genome encapsidated in icosahedral geminate particles. Generally the Begomoviruses are bipartite with respect to their genomic composition. ToLCV from South India is unique in that only DNA A component has been isolated and sequenced thus far and there is no evidence for the presence of DNA B component. In this communication we report the genomic sequences of DNA A component of two strains of Tomato leaf curl Bangalore virus (ToLCBV), one from Bangalore, ToLCBV [Ban 5] and the other from Kolar (70 kms from Bangalore), ToLCBV [Kolar]. We have examined the possibility of recombination between strains/species that co-exist within the same geographical location. A novel method has been used to analyze the variation of ToLCV sequences reported from Bangalore and to assess the frequency and importance of recombinational events among the strains/species existing in Bangalore. The results indicate that there are potential sites of recombination in AV1, AV2, AC1 and intergenic regions of the viral genome and this accounts for the observed variability in these strains/species.Archives of Virology 02/2002; 147(2):255-72. · 2.11 Impact Factor