Dys-regulated activation of a Src tyroine kinase Hck at the Golgi disturbs N-glycosylation of a cytokine receptor Fms.
HIV-1 Nef accelerates the progression to AIDS by binding with and activating a Src kinase Hck, but underlying molecular basis is not understood. We revealed that Nef disturbed N-glycosylation/trafficking of a cytokine receptor Fms in an Hck-dependent manner, a possible trigger to worsen uncontrolled immune system. Here, we provide direct evidence that dys-regulated activation of Hck pre-localized to the Golgi apparatus causes this Fms maturation arrest. A striking change in Hck induced by Nef other than activation was its skewed localization to the Golgi due to predominant Golgi-localization of Nef. Studies with different Nef alleles and their mutants showed a clear correlation among higher Nef-Hck affinity, stronger Hck activation, severe Golgi-localization of Hck and severe Fms maturation arrest. Studies with a newly discovered Nef-Hck binding blocker 2c more clearly showed that skewed Golgi-localization of active Hck was indeed the cause of Fms maturation arrest. 2c blocked Nef-induced skewed Golgi-localization of an active form of Hck (Hck-P2A) and Fms maturation arrest by Nef/Hck-P2A, but showed no inhibition on Hck-P2A kinase activity. Our finding establishes an intriguing link between the pathogenesis of Nef and a newly emerging concept that the Golgi-localized Src kinases regulate the Golgi function.
Hassan
Ranya
R
Division of Hematopoiesis, Center for AIDS Research, Kumamoto University, Kumamoto, Kumamoto, Japan.
Suzu
Shinya
S
Hiyoshi
Masateru
M
Takahashi-Makise
Naoko
N
Ueno
Takamasa
T
Agatsuma
Tsutomu
T
Akari
Hirofumi
H
Komano
Jun
J
Takebe
Yutaka
Y
Motoyoshi
Kazuo
K
Okada
Seiji
S
D000483:Alleles; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D006031:Glycosylation / Q000187:drug effects; D006056:Golgi Apparatus / Q000187:drug effects / Q000201:enzymology*; D006801:Humans; D050505:Mutant Proteins / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D051572:Proto-Oncogene Proteins c-hck / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D054311:nef Gene Products, Human Immunodeficiency Virus / Q000378:metabolism
D050505:Mutant Proteins; D047428:Protein Kinase Inhibitors; D054311:nef Gene Products, Human Immunodeficiency Virus; D016186:Receptor, Macrophage Colony-Stimulating Factor; C496631:HCK protein, human; D051572:Proto-Oncogene Proteins c-hck