title: Binding of the intracellular Fas ligand (FasL) domain to the adaptor protein PSTPIP results in a cytoplasmic localization of FasL.
abstract: The tumor necrosis factor family member Fas ligand (FasL) induces apoptosis in Fas receptor-expressing target cells and is an important cytotoxic effector molecule used by CTL- and NK-cells. In these hematopoietic cells, newly synthesized FasL is stored in specialized secretory lysosomes and only delivered to the cell surface upon activation and target cell recognition. FasL contains an 80-amino acid-long cytoplasmic tail, which includes a proline-rich domain as a bona fide Src homology 3 domain-binding site. This proline-rich domain has been implicated in FasL sorting to secretory lysosomes, and it may also be important for reverse signaling via FasL, which has been described to influence T-cell activation. Here we report the identification of the Src homology 3 domain-containing adaptor protein PSTPIP as a FasL-interacting partner, which binds to the proline-rich domain. PSTPIP co-expression leads to an increased intracellular localization of Fas ligand, thereby regulating extracellular availability and cytotoxic activity of the molecule. In addition, we demonstrate recruitment of the tyrosine phosphatase PTP-PEST by PSTPIP into FasL.PSTPIP.PTP-PEST complexes which may contribute to FasL reverse signaling.
authors.affiliation: Georg-Speyer-Haus, Paul-Ehrlich-Strasse 42-44, Frankfurt D-60596, Germany.
authors.forename: Wiebke
authors.initials: W
authors.lastname: Baum
authors.forename: Vladimir
authors.initials: V
authors.lastname: Kirkin
authors.forename: Sara B Mateus
authors.initials: SB
authors.lastname: Fernández
authors.forename: Robert
authors.initials: R
authors.lastname: Pick
authors.forename: Marcus
authors.initials: M
authors.lastname: Lettau
authors.forename: Ottmar
authors.initials: O
authors.lastname: Janssen
authors.forename: Martin
authors.initials: M
authors.lastname: Zörnig
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000502:physiology*; D000818:Animals; D017209:Apoptosis; D001665:Binding Sites; D019556:COS Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D002469:Cell Separation; D002522:Chlorocebus aethiops; D018920:Coculture Techniques; D003593:Cytoplasm / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000502:physiology*; D018076:DNA, Complementary / Q000378:metabolism; D053222:Fas Ligand Protein; D005434:Flow Cytometry; D005982:Glutathione Transferase / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D008247:Lysosomes / Q000737:chemistry / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D008954:Models, Biological; D010957:Plasmids / Q000378:metabolism; D011392:Proline / Q000737:chemistry; D011485:Protein Binding; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry; D051381:Rats; D015398:Signal Transduction; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism; D014162:Transfection; D048069:Tumor Necrosis Factors / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D014443:Tyrosine / Q000737:chemistry; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; C505662:Faslg protein, rat; D008562:Membrane Glycoproteins; C486382:PSTPIP1 protein, human; D048069:Tumor Necrosis Factors; D049452:Green Fluorescent Proteins; D014443:Tyrosine; D011392:Proline; D005982:Glutathione Transferase; C516738:PTPN12 protein, human; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases; C516739:Ptpn12 protein, mouse; C516740:Ptpn12 protein, rat