title: A novel cysteine-rich neurotrophic factor in Aplysia facilitates growth, MAPK activation, and long-term synaptic facilitation.
abstract: Neurotrophins are critically involved in developmental processes such as neuronal cell survival, growth, and differentiation, as well as in adult synaptic plasticity contributing to learning and memory. Our previous studies examining neurotrophins and memory formation in Aplysia showed that a TrkB ligand is required for MAPK activation, long-term synaptic facilitation (LTF), and long-term memory (LTM) for sensitization. These studies indicate that neurotrophin-like molecules in Aplysia can act as key elements in a functionally conserved TrkB signaling pathway. Here we report that we have cloned and characterized a novel neurotrophic factor, Aplysia cysteine-rich neurotrophic factor (apCRNF), which shares classical structural and functional characteristics with mammalian neurotrophins. We show that apCRNF (1) is highly enriched in the CNS, (2) enhances neurite elongation and branching, (3) interacts with mammalian TrkB and p75(NTR), (4) is released from Aplysia CNS in an activity-dependent fashion, (5) facilitates MAPK activation in a tyrosine kinase dependent manner in response to sensitizing stimuli, and (6) facilitates the induction of LTF. These results show that apCRNF is a native neurotrophic factor in Aplysia that can engage the molecular and synaptic mechanisms underlying memory formation.
authors.affiliation: Department of Neurobiology and Behavior, University of California-Irvine, Irvine, California 92697, USA.
authors.forename: Lu
authors.initials: L
authors.lastname: Pu
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Kopec
authors.forename: Heather D
authors.initials: HD
authors.lastname: Boyle
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Carew
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001048:Aplysia / Q000235:genetics / Q000502:physiology*; D049108:Cell Enlargement; D002478:Cells, Cultured; D002490:Central Nervous System / Q000502:physiology; D003001:Cloning, Molecular; D017774:Long-Term Potentiation / Q000502:physiology*; D008195:Lymnaea; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008969:Molecular Sequence Data; D009046:Motor Neurons / Q000502:physiology; D009414:Nerve Growth Factors / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins; D016501:Neurites / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D017978:Receptors, Growth Factor; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000502:physiology; D013045:Species Specificity; D013569:Synapses / Q000502:physiology*
chemical_list: D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D017978:Receptors, Growth Factor; D017475:Receptors, Nerve Growth Factor; C102285:cysteine-rich neurotrophic factor, Lymnaea stagnalis; C068313:Ngfr protein, rat; D011505:Protein-Tyrosine Kinases