INVESTIGADORES
MAYORGA Luis Segundo
artículos
Título:
PTP1B DEPHOSPHORYLATES NSF AND ELICITS SNARE COMPLEX DISASSEMBLY DURING HUMAN SPERM EXOCYTOSIS
Autor/es:
ZARELLI, V.E.P; RUETE, MC; ROGGERO, CM; MAYORGA, LS; TOMES, CN
Revista:
JOURNAL OF BIOLOGICAL CHEMISTRY
Editorial:
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Referencias:
Año: 2009 vol. 284 p. 10491 - 10503
ISSN:
0021-9258
Resumen:
The reversible phosphorylation of
tyrosyl residues in proteins is a cornerstone of the signaling
pathways that regulate numerous cellular responses. Protein tyrosine
phosphorylation is controlled through the concerted actions of protein
tyrosine kinases and phosphatases. The goal of the present study was to
unveil the mechanisms by which protein tyrosine dephosphorylation
modulates secretion. The acrosome reaction, a specialized type of
regulated exocytosis undergone by sperm, is initiated by calcium and
carried out by a number of players, including tyrosine kinases and
phosphatases, and fusion-related proteins such as Rab3A, α-SNAP, NSF,
SNAREs, complexin, and synaptotagmin VI. We report here that inducers
were unable to elicit the acrosome reaction when permeabilized human
sperm were loaded with anti-PTP1B antibodies or with the
dominant-negative mutant PTP1B D181A; subsequent introduction of wild
type PTP1B or NSF rescued exocytosis. Wild type PTP1Bbut not PTP1B
D181Acaused cis SNARE complex dissociation during the acrosome
reaction through a mechanism involving NSF. Unlike its
non-phosphorylated counterpart, recombinant phospho-NSF failed to
dissociate SNARE complexes from rat brain membranes. These results
strengthen our previous observation that NSF activity is regulated
rather than constitutive during sperm exocytosis and indicate that NSF
must be dephosphorylated by PTP1B to disassemble SNARE complexes.
Interestingly, phospho-NSF served as a substrate for PTP1B in an in vitro assay. Our findings demonstrate that
phosphorylation of NSF on tyrosine residues prevents its SNARE complex
dissociation activity and establish for the first time a role for PTP1B
in the modulation of the membrane fusion machinery.