TitleRegulation of drug transporters
NameZhang, Qiang (author), You, Guofeng (chair), Minko, Tamara (internal member), Michniak-Kohn, Bozena (internal member), Pan, Zui (outside member), Rutgers University, Graduate School - New Brunswick,
Drug delivery systems
DescriptionOrganic anion transporters (OATs) are of great importance in the body disposition of a variety of clinical drugs, including anti-cancer, anti-HIV, antibiotics and anti-inflammatory drugs. Long-term regulations of OATs are mainly mediated by gene expression, and short-term regulations are mainly post-translational modifications such as phosphorylation and glycosylation. In the present study, we investigate the constitutive and PKC-regulated trafficking of both hOAT1 and hOAT4 in COS-7 cells. We observed that the internalization of both transporters was accelerated by PKC activation in COS-7 cells. However, the recycling rate of hOAT1 was not affected by PMA treatment. Using approaches of pharmacology and molecular biology, hOAT1 and hOAT4 transporters have been demonstrated to internalize partly via a dynamin- and clathrin-dependent pathway. We observed that overexpression of NHERF1 significantly delayed the internalization of hOAT4 and this observation suggests that the interaction between the PDZ-binding motif of hOAT4 and NHERF1 is involved in the regulation of hOAT4 trafficking by NHERF1. The simultaneous mutations of both leucine residues (L6A/L7A) of hOAT1 resulted in a complete loss of function and the compete loss of function of L6A/L7A hOAT1 was due to the absence of mature form of this mutant at the cell surface and in total cellular extract. It seems that the L6L7 motif does not play a role in the hOAT1 trafficking from the cell surface, and may be involved in its stability. Ubiquitination of membrane proteins has been shown to regulate internalization, postinternalization sorting and degradation of other membrane proteins. Our current investigation focuses on the internalization and degradation of OATs transporters. The major discoveries from our current study are 1) activation of PKC promotes OAT1 ubiquitination both in vitro and in vivo. 2) OAT1 ubiquitination mainly occurs through K48-linked polyubiquitin chains. 3) K48-linked polyubiquitination plays an essential role in PKC-regulated internalization and degradation of OAT1.
NoteIncludes bibliographical references
Noteby Qiang Zhang
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.