The Na+-Taurocholate Cotransporting Polypeptide Traffics with the Epidermal Growth Factor Receptor

Xintao Wang, Pijun Wang, Wenjun Wang, John W. Murray, Allan W. Wolkoff

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Na+-taurocholate cotransporting polypeptide (ntcp) mediates bile acid transport, also serving as the hepatitis B virus receptor. It traffics in vesicles along microtubules, requiring activity of protein kinase C (PKC)ζ for motility. We have now found that the epidermal growth factor receptor (EGFR) is the target of PKCζ activity and that EGFR and ntcp colocalize in vesicles. ntcp-containing vesicles that are not associated with EGFR have reduced microtubule-based motility, consistent with intracellular accumulation and reduced surface expression of ntcp in cells following EGFR knockdown. Na+-taurocholate cotransporting polypeptide (ntcp) mediates uptake of bile acids as well as serving as the receptor for hepatitis B virus in human liver. Previous studies showed that ntcp traffics on microtubules between the cell surface and endocytic vesicles. Specific inhibition of protein kinase C (PKC)ζ resulted in loss of microtubule-based motility of these vesicles in vitro and in living cells. The aim of this study was to characterize the PKCζ target. Incubation of ntcp-containing endocytic vesicles with γ-32P-ATP revealed a 180 kDa phosphoglycoprotein that was identified as the epidermal growth factor (EGF) receptor (EGFR). Surface biotinylation of HuH7 cells expressing green fluorescent protein (GFP)-ntcp revealed substantially reduced trafficking of ntcp to the cell surface with EGFR knockdown. Microtubule-based motility of ntcp-containing endocytic vesicles was also significantly reduced when they were not associated with EGFR. ntcp was also found to undergo cellular redistribution upon stimulation of cells with EGF, consistent with a model in which ntcp and EGF-EGFR internalize into common endocytic vesicles from which they segregate, trafficking EGF-EGFR to lysosomes and recycling ntcp to the plasma membrane. EGF regulation of ntcp trafficking may play a heretofore unanticipated role in subcellular targeting of ntcp ligands such as hepatitis B.

Original languageEnglish (US)
Pages (from-to)230-244
Number of pages15
Issue number3
StatePublished - Mar 1 2016


  • Bile acid
  • Drug transport
  • Endosome
  • Hepatitis B virus (HBV)
  • Microtubule

ASJC Scopus subject areas

  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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