Human tissue factor pathway inhibitor-2 is internalized by cells and translocated to the nucleus by the importin system.
Tissue factor pathway inhibitor-2 (TFPI-2) is a serine proteinase inhibitor that induces caspase-mediated apoptosis when offered to a variety of tumor cells. In order to investigate the mechanism of TFPI-2-induced apoptosis, we initially studied the uptake and trafficking of TFPI-2 by HT-1080 cells. Exogenously offered TFPI-2 was rapidly internalized and distributed in both the cytosolic and nuclear fractions. Nuclear localization of TFPI-2 was also detected in a variety of endothelial cells constitutively expressing TFPI-2. Nuclear localization of TFPI-2 required a NLS sequence located in its Lys/Arg-rich C-terminal tail comprising residues 191-211, as a TFPI-2 construct lacking the C-terminal tail failed to localize to the nucleus. Complexes of TFPI-2 and importin-alpha were co-immunoprecipitated from cell lysates of HT-1080 cells either offered or overexpressing this protein, providing evidence that TFPI-2 was shuttled to the nucleus by the importin system. Our results provide the initial description of TFPI-2 internalization and translocation to the nucleus in a number of cells.
Kempaiah
Prakasha
P
Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131-0001, USA.
Chand
Hitendra S
HS
Kisiel
Walter
W
D001011:Aorta; D017209:Apoptosis; D002196:Capillaries / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism; D005354:Fibrosarcoma; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D028884:Karyopherins / Q000378:metabolism*; D007668:Kidney / Q000196:embryology; D007700:Kinetics; D018613:Microscopy, Confocal; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000378:metabolism; D012867:Skin / Q000098:blood supply; D014162:Transfection
D006023:Glycoproteins; D028884:Karyopherins; D011994:Recombinant Proteins; C021240:tissue-factor-pathway inhibitor 2