title: Tight junction protein ZO-1 controls organic cation/carnitine transporter OCTN2 (SLC22A5) in a protein kinase C-dependent way.
abstract: OCTN2 (SLC22A5) is an organic cation/carnitine transporter belonging to the solute carrier transporters (SLC) family. OCTN2 is ubiquitously expressed and its presence was shown in various brain cells, including the endothelial cells forming blood-brain barrier, where it was mainly detected at abluminal membrane and in proximity of tight junctions (TJ). Since OCTN2 contains a PDZ-binding domain, the present study was focused on a possible role of transporter interaction with a TJ-associated protein ZO-1, containing PDZ domains and detected in rat Octn2 proteome. We showed previously that activation of protein kinase C (PKC) in rat astrocytes regulates Octn2 surface presence and activity. Regulation of a wild type Octn2 and its deletion mutant without a PDZ binding motif were studied in heterologous expression system in HEK293 cells. Plasma membrane presence of overexpressed Octn2 did not depend on either PKC activation or presence of PDZ-binding motif, anyhow, as assayed in proximity ligation assay, the truncation of PDZ binding motif resulted in a strongly diminished Octn2/ZO-1 interaction and in a decreased transporter activity. The same effects on Octn2 activity were detected upon PKC activation, what correlated with ZO-1 phosphorylation. It is postulated that ZO-1, when not phosphorylated by PKC, keeps Octn2 in an active state, while elimination of this binding in ΔPDZ mutant or after ZO-1 phosphorylation leads to diminution of Octn2 activity.
authors.affiliation: Laboratory of Transport Through Biomembranes, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland.
authors.forename: Dominika
authors.initials: D
authors.lastname: Jurkiewicz
authors.affiliation: Laboratory of Transport Through Biomembranes, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Michalec
authors.affiliation: Core Facility, International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109 Warsaw, Poland; Laboratory of Biochemistry of Lipids, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Skowronek
authors.affiliation: Laboratory of Transport Through Biomembranes, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland. Electronic address: k.nalecz@nencki.gov.pl.
authors.forename: Katarzyna A
authors.initials: KA
authors.lastname: Nałęcz
mesh_terms: D000818:Animals; D004285:Dogs; D057809:HEK293 Cells; D006801:Humans; D061985:Madin Darby Canine Kidney Cells; D027701:Organic Cation Transport Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism*; D015398:Signal Transduction; D000074058:Solute Carrier Family 22 Member 5; D062826:Zonula Occludens-1 Protein / Q000502:physiology*
chemical_list: D027701:Organic Cation Transport Proteins; C492020:SLC22A5 protein, human; D000074058:Solute Carrier Family 22 Member 5; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein; D011493:Protein Kinase C
keywords: OCTN2 (SLC22A5); Protein kinase C; ZO-1, tight junction protein