Project description: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 BrodmannM-bM-^@M-^Ys 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. 739 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 found in the accompanying study, suggesting that the molecular pathophysiology of schizophrenia appears to be predominantly neuronal type-specific. 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 targeted molecular intervention. Gene expression microarray from mRNA isolated from parvalbumin cells in layer 3 of the STG from 8 normal controls and 8 subjects with schizophrenia. There was no significant difference between diagnosis groups for age, sex, and post mortem interval (PMI).
Project description: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. 739 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 found in the accompanying study, suggesting that the molecular pathophysiology of schizophrenia appears to be predominantly neuronal type-specific. 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 targeted molecular intervention.
Project description:Gray matter volume in the cerebral cortex has been consistently found to be decreased in patients with schizophrenia. The superior temporal gyrus (STG) is one of the cortical regions that exhibit the most pronounced volumetric reduction. This reduction is generally thought to reflect, at least in part, decreased number of synapses; the majority of these synapses are believed to be furnished by glutamatergic axon terminals onto the dendritic spines on pyramidal neurons. Pyramidal neurons in the cerebral cortex exhibit layer-specific connectional properties, providing neural circuit structures that support distinct aspects of higher cortical functions. For instance, dendritic spines on pyramidal neurons in layer 3 of the cerebral cortex are targeted by both local and long-range glutamatergic projections in a highly reciprocal fashion. Synchronized activities of pyramidal neuronal networks, especially in the gamma frequency band (i.e. 30-100 Hz), are critical for the integrity of higher cortical functions. Disturbances of these networks may contribute to the pathophysiology of schizophrenia by compromising gamma oscillation. This concept is supported by the following postmortem and clinical observations. First, the density of dendritic spines on pyramidal neurons in layer 3 of the cerebral cortex, including the STG, have been shown to be significantly decreased by 23-66% in subjects with schizophrenia. Second, consistent with these findings, the average somal area of these pyramidal cells is significantly smaller. Third, we have recently found that, in the prefrontal cortex, the density of glutamatergic axonal boutons, of which dendritic spines are their major targets, was significantly decreased by as much as 79% in layer 3 (but not layer 5) in subjects with schizophrenia. Finally, an increasing number of clinical studies have consistently demonstrated that gamma oscillatory synchrony is profoundly impaired in patients with schizophrenia. Furthermore, gamma impairment has been linked to the symptoms and cognitive deficits of the illness and the severity of these symptoms and deficits have in turn been associated with the magnitude of cortical gray matter reduction. Taken together, understanding the molecular underpinnings of pyramidal cell dysfunction will shed important light onto the pathophysiology of cortical dysfunction of schizophrenia. In order to gain insight into the molecular determinants of pyramidal cell dysfunction in schizophrenia, we combined LCM with Affymetrix microarray and high-throughput TaqManM-BM-.-based MegaPlex qRT-PCR approaches, respectively, to elucidate the alterations in messenger ribonucleic acid (mRNA) and microRNA (miRNA) expression profiles of these neurons in layer 3 of the STG. We found that transforming growth factor beta (TGFM-NM-2) and BMP (bone morphogenetic proteins) signaling pathways and many genes that regulate extracellular matrix (ECM), apoptosis and cytoskeleton were dysregulated in schizophrenia. In addition, we identified 10 miRNAs that were differentially expressed in this illness; interestingly, the predicted targets of these miRNAs included the dysregulated pathways and gene networks identified by microarray analysis. Together these findings provide a neurobiological framework within which we can begin to formulate and test specific hypotheses about the molecular mechanisms that underlie pyramidal cell dysfunction in schizophrenia. Gene epxression microarray from RNA isolated from pyramidal cells in layer III of the STG from 9 normal controls and 9 subjects with schizophrenia. There was no significant difference between diagnosis groups for age, sex, and post mortem interval (PMI).
Project description:Schizophrenia is associated with dysfunction of the dorsolateral prefrontal cortex (DLPFC). This dysfunction is manifest as cognitive deficits that appear to arise from disturbances in gamma frequency oscillations. These oscillations are generated in DLPFC layer 3 via reciprocal connections between pyramidal cells and parvalbumin (PV)-containing interneurons. The density of cortical PV neurons is not altered in schizophrenia, but expression levels of several transcripts involved in PV cell function, including PV, are lower in the disease.
Project description:Transcriptional analysis of the superior temporal cortex (BA22) in schizophrenia: Pathway insight into disease pathology and drug development Schizophrenia is a highly debilitating psychiatric disorder which is known to have heritable genetic and environmental components. To gain some insight into the mechanisms underpinning both positive and negative symptoms of the disease, we determined the genome wide expression of mRNA transcripts in post-mortem tissue from the superior temporal cortex (Brodmann Area 22, BA22) in schizophrenic and control patients. The BA22 region is known to mediate the positive pathophysiology of schizophrenia; we compared this to the anterior prefrontal cortex (BA10) from the same subjects, which is known to mediate negative symptoms. Following adjustments for confounding clinical, sample and experimental sources of variation, we carried out gene set enrichment analysis in each region using pathway data. We identified an over-representation of genes involved in cytoskeletal remodelling, neurodevelopment, cell adhesion, cellular signalling, neurotransmission and autophagy. Collectively our analysis indicates a disruption of processes underpinning synaptic plasticity in both regions. Region-specific changes support the dysregulation of distinct pathways in the BA10 and BA22 regions. This may highlight new therapeutic opportunities to treat both negative and positive symptoms of the disease. Post-mortem derived BA22 tissue from schizophrenic and control patients were compared. Age, gender, post-mortem delay and pH of brain lysates data were also captured.
Project description:Parvalbumin neurons, as an important subtype of inhibitory neurons, play a crucial role in the brain. The dysfunctions of those cells are associated with multiple neural system disorders. We carried out whole gene expression studies for the induction process of parvalbumin neurons. We used microarrays to detail the global program of gene expression underlying cellularization and identified distinct classes of up-regulated genes during this process. Induced parvalbumin neuron cells were selected at successive stages of induction process for RNA extraction and hybridization on Affymetrix microarrays. We sought to obtain homogeneous populations of induced parvalbumin neurons at each developmental stage in order to increase the temporal resolution of expression profiles.
Project description:Layer II stellate neurons (entorhinal cortex) and layer III cortical neurons (hippocampus CA1, middle temporal gyrus, posterior cingulate, superior frontal gyrus, primary visual cortex) were gene expression profiled. Brain regions are from individuals who had been diagnosed with mild cognitive impairment. Experiment Overall Design: ~500 neurons were selected from each of 6 brain regions. Total RNA was isolated from each batch of neurons, double round amplified, and hybridized to Affymetrix Human Genome U133 Plus 2.0 arrays.
Project description:Layer II stellate neurons (entorhinal cortex) and layer III cortical neurons (hippocampus CA1, middle temporal gyrus, posterior cingulate, superior frontal gyrus, primary visual cortex) were gene expression profiled. Brain regions are from non-demented individuals with intermediate Alzheimer's disease neuropathologies Keywords: neuronal gene expression profiling