BDNF-Live-Exon-Visualization (BLEV) Allows Differential Detection of BDNF Transcripts in vitro and in vivo.

Bdnf exon-IV and exon-VI transcripts are driven by neuronal activity and are involved in pathologies related to sleep, fear or memory disorders. However, how their differential transcription translates activity changes into long-lasting network changes is elusive. Aiming to trace specifically the network controlled by exon-IV and -VI derived BDNF during activity-dependent plasticity changes, we generated a transgenic reporter mouse for B DNF- l ive- e xon- v isualization (BLEV), in which expression of Bdnf exon-IV and -VI can be visualized by co-expression of CFP and YFP. CFP and YFP expression was differentially activated and targeted in cell lines, primary cultures and BLEV reporter mice without interfering with BDNF protein synthesis. CFP and YFP expression, moreover, overlapped with BDNF protein expression in defined hippocampal neuronal, glial and vascular locations in vivo. So far, activity-dependent BDNF cannot be explicitly monitored independent of basal BDNF levels. The BLEV reporter mouse therefore provides a new model, which can be used to test whether stimulus-induced activity-dependent changes in BDNF expression are instrumental for long-lasting plasticity modifications.

Infection and characterization of Toxoplasma gondii in human induced neurons from patients with brain disorders and healthy controls.

Toxoplasma gondii is a protozoan parasite capable of establishing persistent infection within the brain. Serological studies in humans have linked exposure to Toxoplasma to neuropsychiatric disorders. However, serological studies have not elucidated the related molecular mechanisms within neuronal cells. To address this question, we used human induced neuronal cells derived from peripheral fibroblasts of healthy individuals and patients with genetically-defined brain disorders (i.e. childhood-onset schizophrenia with disease-associated copy number variations). Parasite infection was characterized by differential detection of tachyzoites and tissue cysts in induced neuronal cells. This approach may aid study of molecular mechanisms underlying individual predisposition to Toxoplasma infection linked to neuropathology of brain disorders.

Enhanced conversion of induced neuronal cells (iN cells) from human fibroblasts: Utility in uncovering cellular deficits in mental illness-associated chromosomal abnormalities.

The novel technology of induced neuronal cells (iN cells) is promising for translational neuroscience, as it allows the conversion of human fibroblasts into cells with postmitotic neuronal traits. However, a major technical barrier is the low conversion rate. To overcome this problem, we optimized the conversion media. Using our improved formulation, we studied how major mental illness-associated chromosomal abnormalities may impact the characteristics of iN cells. We demonstrated that our new iN cell culture protocol enabled us to obtain more precise measurement of neuronal cellular phenotypes than previous iN cell methods. Thus, this iN cell culture provides a platform to efficiently obtain possible cellular phenotypes caused by genetic differences, which can be more thoroughly studied in research using other human cell models such as induced pluripotent stem cells.

Is human immunodeficiency virus-mediated dementia an autophagic defect that leads to neurodegeneration?

Autophagy is a cellular process that mediates selective degradation of cellular components in lysosomes. Autophagy may protect against neuronal apoptosis, which is induced in a number of neurodegenerative diseases. Thus, compounds that modulate autophagy could be beneficial to treat neurological disorders characterized by apoptosis such as Parkinson's and Alzheimer's diseases, as well as human-immunodeficiency virus-dementia complex. In this paper, we review new and old evidence on the role of autophagy in neuronal cell survival and we present evidence that humanimmunodeficiency virus may have adapted strategies to alter autophagic pathways in neurons. Moreover, we discuss the usefulness of drugs that facilitate autophagic clearance of proteins that are associated with neurodegeneration.

Molecular profiles of parvalbumin-immunoreactive neurons in the superior temporal cortex in schizophrenia.

Dysregulation of pyramidal cell network function by the soma- and axon-targeting inhibitory neurons that contain the calcium-binding protein parvalbumin (PV) represents a core pathophysiological feature of schizophrenia. In order to gain insight into the molecular basis of their functional impairment, we used laser capture microdissection (LCM) to isolate PV-immunolabeled neurons from layer 3 of Brodmann's area 42 of the superior temporal gyrus (STG) from postmortem schizophrenia and normal control brains. We then extracted ribonucleic acid (RNA) from these neurons and determined their messenger RNA (mRNA) expression profile using the Affymetrix platform of microarray technology. Seven hundred thirty-nine mRNA transcripts were found to be differentially expressed in PV neurons in subjects with schizophrenia, including genes associated with WNT (wingless-type), NOTCH, and PGE2 (prostaglandin E2) signaling, in addition to genes that regulate cell cycle and apoptosis. Of these 739 genes, only 89 (12%) were also differentially expressed in pyramidal neurons, as described in the accompanying paper, suggesting that the molecular pathophysiology of schizophrenia appears to be predominantly neuronal type specific. In addition, we identified 15 microRNAs (miRNAs) that were differentially expressed in schizophrenia; enrichment analysis of the predicted targets of these miRNAs included the signaling pathways found by microarray to be dysregulated in schizophrenia. Taken together, findings of this study provide a neurobiological framework within which hypotheses of the molecular mechanisms that underlie the dysfunction of PV neurons in schizophrenia can be generated and experimentally explored and, as such, may ultimately inform the conceptualization of rational targeted molecular intervention for this debilitating disorder.

Developmental pattern of perineuronal nets in the human prefrontal cortex and their deficit in schizophrenia.

BACKGROUND: Perineuronal nets (PNNs) are extracellular matrix structures that enwrap many neurons in the brain. They regulate the postnatal experience-dependent maturation of brain circuits and maintain their functional integrity in the mature brain by stabilizing their synaptic architecture. METHODS: Eighty-six postmortem human brains were included in this study. We used Wisteria Floribunda agglutinin histochemistry to visualize PNNs to investigate whether the densities of PNNs in the prefrontal cortex (PFC) and primary visual cortex were altered in subjects with schizophrenia or bipolar disorder. In addition, we quantified the normal postnatal development of PNNs in the human PFC. RESULTS: The densities of PNNs were decreased by 70%-76% in layers 3 and 5 of the PFC in schizophrenia, compared with the normal control subjects, but not in bipolar disorder. This finding was replicated in a separate group of schizophrenia and normal control subjects. In addition, PNN densities in the primary visual cortex were unaltered in either condition. Finally, the number of PNNs in the PFC increased during postnatal development through the peripubertal period until late adolescence and early adulthood. CONCLUSIONS: These findings suggest that PNN deficit contributes to PFC dysfunction in schizophrenia. That the timing of PNN development overlaps with the period when schizophrenia symptomatology gradually emerges raises the possibility that aberrant PNN formation might contribute to the onset of illness. Thus, characterization of the molecular mechanisms underlying PNN deficit might have important implications for the conceptualization of novel strategies for the diagnosis, treatment, early intervention, and prevention of schizophrenia.