An Aplysia Egr homolog is rapidly and persistently regulated by long-term sensitization training

Cyriac A, Holmes G, Lass J, Belchenko D, Calin-Jageman RJ, Calin-Jageman IE

Neurobiol Learn Mem 2013 May;102:43-51

PMID: 23567107

Abstract

The Egr family of transcription factors plays a key role in long-term plasticity and memory in a number of vertebrate species. Here we identify and characterize ApEgr (GenBank: KC608221), an Egr homolog in the marine mollusk Aplysia californica. ApEgr codes for a predicted 593-amino acid protein with the highly conserved trio of zinc-fingered domains in the C-terminus that characterizes the Egr family of transcription factors. Promoter analysis shows that the ApEgr protein selectively recognizes the GSG motif recognized by vertebrate Egrs. Like mammalian Egrs, ApEgr is constitutively expressed in a range of tissues, including the CNS. Moreover, expression of ApEgr is bi-directionally regulated by changes in neural activity. Of most interest, the association between ApEgr function and memory may be conserved in Aplysia, as we observe rapid and long-lasting up-regulation of expression after long-term sensitization training. Taken together, our results suggest that Egrs may have memory functions that are conserved from mammals to mollusks.

Transcriptional changes following long-term sensitization training and in vivo serotonin exposure in Aplysia californica

Bonnick K, Bayas K, Belchenko D, Cyriac A, Dove M, Lass J, McBride B, Calin-Jageman IE, Calin-Jageman RJ

PLoS ONE 2012;7(10):e47378

PMID: 23056638

Abstract

We used Aplysia californica to compare the transcriptional changes evoked by long-term sensitization training and by a treatment meant to mimic this training, in vivo exposure to serotonin. We focused on 5 candidate plasticity genes which are rapidly up-regulated in the Aplysia genus by in vivo serotonin treatment, but which have not yet been tested for regulation during sensitization: CREB1, matrilin, antistasin, eIF3e, and BAT1 homolog. CREB1 was rapidly up-regulated by both treatments, but the regulation following training was transient, falling back to control levels 24 hours after training. This suggests some caution in interpreting the proposed role of CREB1 in consolidating long-term sensitization memory. Both matrilin and eIF3e were up-regulated by in vivo serotonin but not by long-term sensitization training. This suggests that in vivo serotonin may produce generalized transcriptional effects that are not specific to long-term sensitization learning. Finally, neither treatment produced regulation of antistasin or BAT1 homolog, transcripts regulated by in vivo serotonin in the closely related Aplysia kurodai. This suggests either that these transcripts are not regulated by experience, or that transcriptional mechanisms of memory may vary within the Aplysia genus.