Phosphorylation of extra-nuclear ERK/MAPK is required for long-term memory consolidation in the crab Chasmagnathus

FELD M; DIMANT B; DELORENZI A; COSO O; ROMANO A

NEUROBIOLOGY OF LEARNING AND MEMORY

Elsevier/North-Holland Biomedical Press

Lugar: Netherlands; Año: 2005 vol. 158 p. 251 - 261

1074-7427

It was previously demonstrated that mitogen-activated protein kinase (MAPK) signaling plays a pivotal role in neural plasticity and memory processes both in rodents and mollusks. Although the MAPK pathways are highly conserved, no evidence was found for its participation in memory models in other animal groups. Here we found ERK-like and JNK-like cross-immunoreactivity in the crab brain with phospho-specific antibodies and we estimated ERK and JNK activity during long-term memory consolidation in the context–signal learning paradigm of the crab Chasmagnathus. At 0, 1, 3 and 6 h after training ERK and JNK activity was measured. ERK-like activation was found 1 h after spaced training in cytosolic but not in nuclear fractions of brain homogenates, while JNK activity remained unchanged in both fractions. Passive (context exposure) and active (continuous stimulation) controls showed cytosolic ERK and JNK activation immediately after training, which decayed 1 h later. In coincidence with this time course of activity, an ERK1/2 pathway inhibitor, PD098059, induced amnesia only when administered 45 min after training but not when administered immediately pre- or post-training. These data support that: (1) cytoplasmic but not nuclear ERK substrates must be differentially phosphorylated during memory consolidation, and (2) ERK phosphorylation and consequent activation 1 h after training is necessary for long-term memory consolidation in this arthropod model.