Differential nucleocytoplasmic trafficking between the related endocytic proteins Eps15 and Eps15R.
Eps15 and Eps15R are constitutive components of clathrin-coated pits that are required for clathrin-dependent endocytosis. The most striking difference between these two related proteins is that Eps15R is also found in the nucleus, whereas Eps15 is excluded from this compartment at steady state. To better understand the individual functions of these two proteins, the mechanisms responsible for their different localization were investigated. Interestingly, some mutants of Eps15 were found in the nucleus. This nuclear localization was correlated with the loss of the last approximately 100 amino acids of Eps15, suggesting the presence of a nuclear export signal (NES) within this region. As expected, the last 25 amino acids contain a leucine-rich sequence matching with classical NESs, show a leptomycin B-sensitive nuclear export activity, and bind to the exportin CRM1 in a leucine residue-dependent manner. In contrast, no NES could be found in Eps15R, a result in keeping with its constitutive nuclear localization that appears to be regulated by alternative splicing. Altogether, these results are the first characterization of nucleocytoplasmic shuttling signals for endocytic proteins. They also provide an explanation for the different nuclear localization of Eps15 and Eps15R and further evidence for a possible nuclear function for Eps15 protein family members.
Poupon
Viviane
V
INSERM E9925, Faculté Necker-Enfants Malades, 156 rue de Vaugirard, 75730 Paris Cedex 15, France.
Polo
Simona
S
Vecchi
Manuela
M
Martin
Gwendal
G
Dautry-Varsat
Alice
A
Cerf-Bensussan
Nadine
N
Di Fiore
Pier Paolo
PP
Benmerah
Alexandre
A
D016475:3T3 Cells; D021581:Active Transport, Cell Nucleus; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D002135:Calcium-Binding Proteins; C486206:EPS15 protein, human; C082729:Eps15 protein, mouse; C094318:Eps15-rs protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins