Immunohistochemical distribution and functional characterization of an organic anion transporting polypeptide 2 (oatp2)

Abstract

The rabbit polyclonal antibody against rat organic anion transporting polypeptide 2 (oatp2) was raised and immunoaffinity-purified. Western blot analysis for oatp2 detected two bands ( 74 and 76 kDa) in rat brain and a single band (76 kDa) in the liver. By immunohistochemical analysis, the oatp2 immunoreactivity was specifically high at the basolateral membrane of rat hepatocytes. Functionally, the oatp2-expressing oocytes were found to transport dehydroepiandrosterone sulfate, delta1 opioid receptor agonist [D-Pen2,D-Pen5]enkephalin, Leuenkephalin, and biotin significantly, as well as the substrates previously reported. These data reveal the exact distribution of the rat oatp2 at the protein level in the liver, and that oatp2 appears to be involved in the multispecificity of the uptaking substrates in the liver and brain.

Conditionally Immortalized Cell Lines as a New In Vitro Model for the Study of Barrier Functions

“…37) Organic anion-transporting polypeptide2 (oatp2) protein has been cloned 38,39) and detected in rat liver hepatocytes, brain capillary endothelial cells, and the choroid plexus epithelial cells, suggeting that it plays an important role in the disposition of some drugs. [40][41][42] Although oatp2 is located at the BBB, it is not yet clear whether oatp2 is involved in the influx or efflux transport of organic anions at the BBB. TM-BBB cells exhibit a concentration-dependence for dehydroepiandrosterone sulfate (DHEAS), a neuroactive steroid 43) and a substrate for oatp2, 42,44) and the cell has a K m of 34.4 mM.…”

Molecular cloning and functional characterization of the mouse organic-anion-transporting polypeptide 1 (Oatp1) and mapping of the gene to chromosome X

“…Oatp1 is expressed, in addition to the sinusoidal membrane of hepatocytes [9], in the apical membrane of the proximal tubule [10] and in the apical membrane of the choroid plexus [11]. Oatp2 protein was detected in rat liver hepatocytes, endothelial cells of the blood\brain barrier [12][13][14] and the choroid plexus [12]. On the basis of Northern-blot analysis, Oatp3 is expressed in the kidney, liver and the retina [4].…”

Improved Brain Uptake and Pharmacological Activity of Dalargin Using a Peptide-Vector-Mediated Strategy

“…One of the problems associated with the inability of many peptides and proteins to accumulate in the brain in therapeutically meaningful amounts is the efflux transport systems. For example, it has been shown that the selective ␦-opioid receptors against [D-Pen 2 ,D-Pen 5 ]-enkephalin (DPDPE) has a poor BBB permeability that is explained in part by P-glycoprotein (P-gp)-mediated efflux, and DPDPE is also a substrate of the rat organic anion transporting polypeptide 2 (OATP2) and human OATP-A (Kakyo et al, 1999;Gao et al, 2000).To overcome the limited access of drugs to the brain, various strategies have been applied to direct central nervous system (CNS) drugs into the brain . Most of these methods are invasive, such as surgical implantation of an intraventricular catheter followed by drug infusion into the ventricular compartment, transient opening of the tight junctions by the intracarotid infusion of a hypertonic solution (Chamberlain et al, 1993;Kroll and Neuwelt, 1998;Temsamani et al, 2000), or intracarotid arterial infusion of vasoactive substances such as bradykinin or bradykinin analogs (Bartus et al, 1996).…”

“…One of the problems associated with the inability of many peptides and proteins to accumulate in the brain in therapeutically meaningful amounts is the efflux transport systems. For example, it has been shown that the selective ␦-opioid receptors against [D-Pen 2 ,D-Pen 5 ]-enkephalin (DPDPE) has a poor BBB permeability that is explained in part by P-glycoprotein (P-gp)-mediated efflux, and DPDPE is also a substrate of the rat organic anion transporting polypeptide 2 (OATP2) and human OATP-A (Kakyo et al, 1999;Gao et al, 2000).…”