The closure of Pak1-dependent macropinosomes requires the phosphorylation of CtBP1/BARS.
Membrane fission is an essential process in membrane trafficking and other cellular functions. While many fissioning and trafficking steps are mediated by the large GTPase dynamin, some fission events are dynamin independent and involve C-terminal-binding protein-1/brefeldinA-ADP ribosylated substrate (CtBP1/BARS). To gain an insight into the molecular mechanisms of CtBP1/BARS in fission, we have studied the role of this protein in macropinocytosis, a dynamin-independent endocytic pathway that can be synchronously activated by growth factors. Here, we show that upon activation of the epidermal growth factor receptor, CtBP1/BARS is (a) translocated to the macropinocytic cup and its surrounding membrane, (b) required for the fission of the macropinocytic cup and (c) phosphorylated on a specific serine that is a substrate for p21-activated kinase, with this phosphorylation being essential for the fission of the macropinocytic cup. Importantly, we also show that CtBP1/BARS is required for macropinocytic internalization and infection of echovirus 1. These results provide an insight into the molecular mechanisms of CtBP1/BARS activation in membrane fissioning, and extend the relevance of CtBP1/BARS-induced fission to human viral infection.
Liberali
Prisca
P
Laboratory of Cell Regulation, Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro (Chieti), Italy.
Kakkonen
Elina
E
Turacchio
Gabriele
G
Valente
Carmen
C
Spaar
Alexander
A
Perinetti
Giuseppe
G
Böckmann
Rainer A
RA
Corda
Daniela
D
Colanzi
Antonino
A
Marjomaki
Varpu
V
Luini
Alberto
A
D000199:Actins / Q000378:metabolism; D000429:Alcohol Oxidoreductases / Q000378:metabolism* / Q000648:ultrastructure; D045744:Cell Line, Tumor; D022081:Cell Surface Extensions / Q000187:drug effects / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000648:ultrastructure; D029822:Enterovirus B, Human / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D006801:Humans; D038982:Integrin alpha2beta1 / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010873:Pinocytosis / Q000187:drug effects; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D054462:p21-Activated Kinases / Q000737:chemistry / Q000378:metabolism*
D000199:Actins; D004268:DNA-Binding Proteins; D038982:Integrin alpha2beta1; D004815:Epidermal Growth Factor; D000429:Alcohol Oxidoreductases; C096794:C-terminal binding protein; D054462:p21-Activated Kinases