Fibroblast growth factor 14 (FGF14) is a member of the intracellular FGFs, a group of proteins with roles in neuronal ion channel regulation and synaptic transmission. We have previously demonstrated that a male Fgf14-/- mouse model recapitulates salient endophenotypes of synaptic dysfunction and behaviors associated with schizophrenia (SZ). As the underlying etiology of SZ and its sex-specific onset remain elusive, the Fgf14-/- model provides a valuable tool to interrogate pathways that might be related to the disease mechanism. Here, we performed label free quantitative proteomics and bioinformatics to identify enriched pathways at the proteome level in the male and female hippocampi from Fgf14+/+ and Fgf14-/- mice. We discovered that many differentially expressed proteins in Fgf14-/- animals are associated with SZ. In addition, measured changes in the proteome and signaling pathways were predominantly sex-specific with the male Fgf14-/- being distinctly enriched for pathways associated with neuropsychiatric disorders and addiction and the female exhibiting modest changes. In the male Fgf14-/- mouse the major protein changes that could in part explain the previously described neurotransmission and behavioral phenotype of this model were loss of ALDH1A1 and PRKAR2B. ALDH1A1 has been shown to mediate an alternative pathway for GABA synthesis, while PRKAR2B is essential for dopamine 2 receptor signaling, which is the basis of current antipsychotics. Collectively, our results provide new insights in the role of FGF14 and support the use of the Fgf14-/- mouse as a useful preclinical model of SZ for generating hypothesis on the disease mechanism, sex-specific manifestation and therapy.

Fear extinction requires coordinated neural activity within the amygdala and medial prefrontal cortex (mPFC). Any behavior has a transcriptomic signature that is modified by environmental experiences, and specific genes are involved in functional plasticity and synaptic wiring during fear extinction. Here, we investigated the effects of optogenetic manipulations of prelimbic (PrL) pyramidal neurons on amygdala gene expression to analyze the specific transcriptional pathways involved in adaptive and maladaptive fear extinction. To this aim, transgenic mice were (or not) fear-conditioned and during the extinction phase they received optogenetic (or sham) stimulations over PrL pyramidal neurons. At the end of behavioral testing, electrophysiological (neural cellular excitability and Excitatory Post-Synaptic Currents) and morphological (spinogenesis) correlates were evaluated in the PrL pyramidal neurons. Furthermore, transcriptomic cell-specific RNA-analyses (differential gene expression profiling and functional enrichment analyses) were performed in amygdala pyramidal neurons. Our results show that the optogenetic activation of PrL pyramidal neurons in fear-conditioned mice induces fear extinction deficits, reflected in an increase of cellular excitability, excitatory neurotransmission, and spinogenesis of PrL pyramidal neurons, and in strong modifications of the transcriptome of amygdala pyramidal neurons. Understanding the electrophysiological, morphological and transcriptomic architecture of fear extinction may facilitate the comprehension of fear-related disorders.