Small molecule inhibition of HIV-1-induced MHC-I down-regulation identifies a temporally regulated switch in Nef action.
HIV-1 Nef triggers down-regulation of cell-surface MHC-I by assembling a Src family kinase (SFK)-ZAP-70/Syk-PI3K cascade. Here, we report that chemical disruption of the Nef-SFK interaction with the small molecule inhibitor 2c blocks assembly of the multi-kinase complex and represses HIV-1-mediated MHC-I down-regulation in primary CD4(+) T-cells. 2c did not interfere with the PACS-2-dependent trafficking of Nef required for the Nef-SFK interaction or the AP-1 and PACS-1-dependent sequestering of internalized MHC-I, suggesting the inhibitor specifically interfered with the Nef-SFK interaction required for triggering MHC-I down-regulation. Transport studies revealed Nef directs a highly regulated program to down-regulate MHC-I in primary CD4(+) T-cells. During the first two days after infection, Nef assembles the 2c-sensitive multi-kinase complex to trigger down-regulation of cell-surface MHC-I. By three days postinfection Nef switches to a stoichiometric mode that prevents surface delivery of newly synthesized MHC-I. Pharmacologic inhibition of the multi-kinase cascade prevents the Nef-dependent block in MHC-I transport, suggesting the signaling and stoichiometric modes are causally linked. Together, these studies resolve the seemingly controversial models that describe Nef-induced MHC-I down-regulation and provide new insights into the mechanism of Nef action.
Dikeakos
Jimmy D
JD
Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA.
Atkins
Katelyn M
KM
Thomas
Laurel
L
Emert-Sedlak
Lori
L
Byeon
In-Ja L
IJ
Jung
Jinwon
J
Ahn
Jinwoo
J
Wortman
Matthew D
MD
Kukull
Ben
B
Saito
Masumichi
M
Koizumi
Hirokazu
H
Williamson
Danielle M
DM
Hiyoshi
Masateru
M
Barklis
Eric
E
Takiguchi
Masafumi
M
Suzu
Shinya
S
Gronenborn
Angela M
AM
Smithgall
Thomas E
TE
Thomas
Gary
G
D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000201:enzymology / Q000821:virology; D002460:Cell Line; D015536:Down-Regulation / Q000187:drug effects*; D004705:Endocytosis / Q000187:drug effects; D015497:HIV-1 / Q000187:drug effects*; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D006801:Humans; D009097:Multienzyme Complexes / Q000378:metabolism; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D054852:Small Molecule Libraries / Q000494:pharmacology*; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism; D054311:nef Gene Products, Human Immunodeficiency Virus / Q000378:metabolism*; D019061:src-Family Kinases / Q000378:metabolism
D015395:Histocompatibility Antigens Class I; D009097:Multienzyme Complexes; C491914:PACS1 protein, human; D054852:Small Molecule Libraries; D018808:Transcription Factor AP-1; D033921:Vesicular Transport Proteins; D054311:nef Gene Products, Human Immunodeficiency Virus; D019869:Phosphatidylinositol 3-Kinases; D019061:src-Family Kinases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human