Mutation in the TRKB Cholesterol Recognition Site that blocks Antidepressant Binding does not Influence the Basal or BDNF-Stimulated Activation of TRKB
Caroline Biojone, Cecilia Cannarozzo, Nina Seiffert, Cassiano R. A. F. Diniz, Cecilia A. Brunello, Eero Castrén, Plinio Casarotto
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引用次数: 0
Abstract
Brain-derived neurotrophic factor (BDNF) acting upon its receptor Neurotrophic tyrosine kinase receptor 2 (NTRK2, TRKB) plays a central role in the development and maintenance of synaptic function and activity- or drug-induced plasticity. TRKB possesses an inverted cholesterol recognition and alignment consensus sequence (CARC), suggesting this receptor can act as a cholesterol sensor. We have recently shown that antidepressant drugs directly bind to the CARC domain of TRKB dimers, and that this binding as well as biochemical and behavioral responses to antidepressants are lost with a mutation in the TRKB CARC motif (Tyr433Phe). However, it is not clear if this mutation can also compromise the receptor function and lead to behavioral alterations. Here, we observed that Tyr433Phe mutation does not alter BDNF binding to TRKB, or BDNF-induced dimerization of TRKB. In this line, primary cultures from embryos of heterozygous Tyr433Phe mutant mice (hTRKB.Tyr433Phe) are responsive to BDNF-induced activation of TRKB, and samples from adult mice do not show any difference on TRKB activation compared to wild-type littermates (TRKB.wt). The behavioral phenotype of hTRKB.Tyr433Phe mice is indistinguishable from the wild-type mice in cued fear conditioning, contextual discrimination task, or the elevated plus maze, whereas mice heterozygous to BDNF null allele show a phenotype in context discrimination task. Taken together, our results indicate that Tyr433Phe mutation in the TRKB CARC motif does not show signs of loss-of-function of BDNF responses, while antidepressant binding to TRKB and responses to antidepressants are lost in Tyr433Phe mutants, making them an interesting mouse model for antidepressant research.
期刊介绍:
Cellular and Molecular Neurobiology publishes original research concerned with the analysis of neuronal and brain function at the cellular and subcellular levels. The journal offers timely, peer-reviewed articles that describe anatomic, genetic, physiologic, pharmacologic, and biochemical approaches to the study of neuronal function and the analysis of elementary mechanisms. Studies are presented on isolated mammalian tissues and intact animals, with investigations aimed at the molecular mechanisms or neuronal responses at the level of single cells. Cellular and Molecular Neurobiology also presents studies of the effects of neurons on other organ systems, such as analysis of the electrical or biochemical response to neurotransmitters or neurohormones on smooth muscle or gland cells.