| 1 | PLoS ONE 2012 -1 7: e43904 |
|---|---|
| PMID | 22937123 |
| Title | Selective expression of KCNS3 potassium channel ?-subunit in parvalbumin-containing GABA neurons in the human prefrontal cortex. |
| Abstract | The cognitive deficits of schizophrenia appear to be associated with altered cortical GABA neurotransmission in the subsets of inhibitory neurons that express either parvalbumin (PV) or somatostatin (SST). Identification of molecular mechanisms that operate selectively in these neurons is essential for developing targeted therapeutic strategies that do not influence other cell types. Consequently, we sought to identify, in the human cortex, gene products that are expressed selectively by PV and/or SST neurons, and that might contribute to their distinctive functional properties. Based on previously reported expression patterns in the cortex of mice and humans, we selected four genes: KCNS3, LHX6, KCNAB1, and PPP1R2, encoding K(+) channel Kv9.3 modulatory ?-subunit, LIM homeobox protein 6, K(+) channel Kv?1 subunit, and protein phosphatase 1 regulatory subunit 2, respectively, and examined their colocalization with PV or SST mRNAs in the human prefrontal cortex using dual-label in situ hybridization with (35)S- and digoxigenin-labeled antisense riboprobes. KCNS3 mRNA was detected in almost all PV neurons, but not in SST neurons, and PV mRNA was detected in >90% of KCNS3 mRNA-expressing neurons. LHX6 mRNA was detected in almost all PV and >90% of SST neurons, while among all LHX6 mRNA-expressing neurons 50% expressed PV mRNA and >44% expressed SST mRNA. KCNAB1 and PPP1R2 mRNAs were detected in much larger populations of cortical neurons than PV or SST neurons. These findings indicate that KCNS3 is a selective marker of PV neurons, whereas LHX6 is expressed by both PV and SST neurons. KCNS3 and LHX6 might be useful for characterizing cell-type specific molecular alterations of cortical GABA neurotransmission and for the development of novel treatments targeting PV and/or SST neurons in schizophrenia. |
| SCZ Keywords | schizophrenia |
| 2 | Am J Psychiatry 2012 Oct 169: 1082-91 |
| PMID | 22983435 |
| Title | Deficits in transcriptional regulators of cortical parvalbumin neurons in schizophrenia. |
| Abstract | In schizophrenia, alterations within the prefrontal cortical GABA system appear to be most prominent in neurons that contain parvalbumin or somatostatin but not calretinin. The transcription factors LHX6 and Sox6 play critical roles in the specification, migration, and maturation of parvalbumin and somatostatin neurons, but not calretinin neurons, and continue to be strongly expressed in this cell type-specific manner in the prefrontal cortex of adult humans. The authors investigated whether LHX6 and/or Sox6 mRNA levels are deficient in schizophrenia, which may contribute to cell type-specific disturbances in cortical parvalbumin and somatostatin neurons. The authors used quantitative PCR and in situ hybridization with film and grain counting analyses to quantify mRNA levels in postmortem samples of prefrontal cortex area 9 of 42 schizophrenia subjects and 42 comparison subjects who had no psychiatric diagnoses in life, as well as antipsychotic-exposed monkeys. In schizophrenia subjects, the authors observed lower mRNA levels for LHX6, parvalbumin, somatostatin, and glutamate decarboxylase (GAD67; the principal enzyme in GABA synthesis), but not Sox6 or calretinin. Cluster analysis revealed that a subset of schizophrenia subjects consistently showed the most severe deficits in the affected transcripts. Grain counting analyses revealed that some neurons that normally express LHX6 were not detectable in schizophrenia subjects. Finally, lower LHX6 mRNA levels were not attributable to psychotropic medications or illness chronicity. These data suggest that in a subset of individuals with schizophrenia, LHX6 deficits may contribute to a failure of some cortical parvalbumin and somatostatin neurons to successfully migrate or develop a detectable GABA-ergic phenotype. |
| SCZ Keywords | schizophrenia |
| 3 | Stem Cell Res 2013 Jul 11: 647-56 |
| PMID | 23672829 |
| Title | Enhanced derivation of mouse ESC-derived cortical interneurons by expression of Nkx2.1. |
| Abstract | Forebrain GABAergic interneurons are divided into subgroups based on their neurochemical markers, connectivity and physiological properties. Abnormal interneuron function is implicated in the pathobiology of neurological disorders such as schizophrenia, autism, and epilepsy. Studies on interneuron development and their role in disease would benefit from an efficient mechanism for the production and selection of specific interneuron subgroups. In this study, we engineered a mouse embryonic stem cell (mESC) line for doxycycline-inducible expression of Nkx2.1, a required transcription factor for cortical interneurons derived from the medial ganglionic eminence (MGE). This mESC line was modified to express GFP in LHX6(+) cells, a marker of newly postmitotic and mature MGE-derived cortical interneurons. The addition of doxycycline to differentiating ESCs efficiently induced Nkx2.1 protein and increased the production of GFP(+) cells. Transplantation of GFP(+) putative interneuron precursors resulted in migratory, morphological, and neurochemical features consistent with cortical interneuron fates. To test the hypothesis that Sonic hedgehog (Shh) primarily influences cortical interneuron fate determination through the induction of Nkx2.1, ESCs were grown with doxycycline and the Shh antagonist cyclopamine. We found induced Nkx2.1 renders Shh signaling dispensable for the generation of MGE-derived interneurons. These results demonstrate that inducible expression of fate determining genes in embryonic stem cells can be used to study fate determination of the developing forebrain. |
| SCZ Keywords | schizophrenia |
| 4 | Stem Cells 2014 Jul 32: 1789-804 |
| PMID | 24648391 |
| Title | Efficient specification of interneurons from human pluripotent stem cells by dorsoventral and rostrocaudal modulation. |
| Abstract | GABAergic interneurons regulate cortical neural networks by providing inhibitory inputs, and their malfunction, resulting in failure to intricately regulate neural circuit balance, is implicated in brain diseases such as schizophrenia, Autism, and Epilepsy. During early development, GABAergic interneuron progenitors arise from the ventral telencephalic area such as medial ganglionic eminence (MGE) and caudal ganglionic eminence (CGE) by the actions of secreted signaling molecules from nearby organizers, and migrate to their target sites where they form local synaptic connections. In this study, using combinatorial and temporal modulation of developmentally relevant dorsoventral and rostrocaudal signaling pathways (SHH, Wnt, and FGF8), we efficiently generated MGE cells from multiple human pluripotent stem cells. Most importantly, modulation of FGF8/FGF19 signaling efficiently directed MGE versus CGE differentiation. Human MGE cells spontaneously differentiated into LHX6-expressing GABAergic interneurons and showed migratory properties. These human MGE-derived neurons generated GABA, fired action potentials, and displayed robust GABAergic postsynaptic activity. Transplantation into rodent brains results in well-contained neural grafts enriched with GABAergic interneurons that migrate in the host and mature to express somatostatin or parvalbumin. Thus, we propose that signaling modulation recapitulating normal developmental patterns efficiently generate human GABAergic interneurons. This strategy represents a novel tool in regenerative medicine, developmental studies, disease modeling, bioassay, and drug screening. |
| SCZ Keywords | schizophrenia |
| 5 | Schizophr Bull 2014 Sep 40: 1053-61 |
| PMID | 24837792 |
| Title | Cortical inhibitory neuron disturbances in schizophrenia: role of the ontogenetic transcription factor Lhx6. |
| Abstract | Disturbances in parvalbumin- and somatostatin-containing neurons, including deficits in the gamma-aminobutyric acid (GABA)-synthesizing enzyme GAD67 in the prefrontal cortex (PFC) in schizophrenia, may be related to disrupted pre- and/or postnatal development. Deficits in the transcription factor LHX6, which regulates parvalbumin and somatostatin neuron development, are associated with GAD67 deficits in schizophrenia. Therefore, we investigated the potential pre- and postnatal roles of LHX6 in GABA-related disturbances using qPCR and/or in situ hybridization to quantify PFC levels of (1) LHX6 mRNA in a new cohort of schizophrenia subjects; (2) LHX6 mRNA in monkeys across postnatal development; (3) GABA-related mRNAs in LHX6 heterozygous (LHX6+/?) mice, which model LHX6 deficits in schizophrenia; and (4) LHX6 mRNA in GAD67+/? mice, which model GAD67 deficits in schizophrenia. LHX6 mRNA levels were lower (?15%) in schizophrenia and correlated with lower GAD67 mRNA levels. In addition, LHX6 mRNA levels declined 24% from the perinatal to prepubertal periods then stabilized in monkeys. Finally, GAD67, parvalbumin, and somatostatin mRNAs were not altered in LHX6+/? mice, and LHX6 mRNA was not altered in GAD67+/? mice. These data suggest that PFC LHX6 and GAD67 mRNA deficits are common components of GABA neuron pathology in schizophrenia. An excessive early postnatal decline in LHX6 mRNA might contribute to LHX6 mRNA deficits in schizophrenia. However, a partial loss of LHX6 is not sufficient in isolation to produce deficits in GAD67 mRNA and vice versa, suggesting that the concurrence of LHX6 and GAD67 mRNA deficits in schizophrenia may instead be the consequence of a common upstream factor. |
| SCZ Keywords | schizophrenia |
| 6 | Front Cell Neurosci 2014 -1 8: 190 |
| PMID | 25071449 |
| Title | DISC1 knockdown impairs the tangential migration of cortical interneurons by affecting the actin cytoskeleton. |
| Abstract | Disrupted-in-schizophrenia 1 (DISC1) is a risk gene for a spectrum of major mental disorders. It has been shown to regulate radial migration as well as dendritic arborization during neurodevelopment and corticogenesis. In a previous study we demonstrated through in vitro experiments that DISC1 also controls the tangential migration of cortical interneurons originating from the medial ganglionic eminence (MGE). Here we first show that DISC1 is necessary for the proper tangential migration of cortical interneurons in the intact brain. Expression of EGFP under the LHX6 promotor allowed us to analyze exclusively interneurons transfected in the MGE after in utero electroporation. After 3 days in utero, DISC1 deficient interneurons displayed prolonged leading processes and, compared to control, fewer neurons reached the cortex. Time-lapse video microscopy of cortical feeder-layers revealed a decreased migration velocity due to a reduction of soma translocations. Immunostainings indicated that DISC1 is co-localized with F-actin in the growth cone-like structure of the leading process. DISC1 knockdown reduced F-actin levels whereas the overall actin level was not altered. Moreover, DISC1 knockdown also decreased levels of phosphorylated Girdin, which cross-links F-actin, as well as the Girdin-activator pAkt. In contrast, using time-lapse video microscopy of fluorescence-tagged tubulin and EB3 in fibroblasts, we found no effects on microtubule polymerization when DISC1 was reduced. However, DISC1 affected the acetylation of microtubules in the leading processes of MGE-derived cortical interneurons. Together, our results provide a mechanism how DISC1 might contribute to interneuron migration thereby explaining the reduced number of specific classes of cortical interneurons in some DISC1 mouse models. |
| SCZ Keywords | schizophrenia |
| 7 | Schizophr. Res. 2015 Sep 167: 12-7 |
| PMID | 25464914 |
| Title | Chemokine receptors and cortical interneuron dysfunction in schizophrenia. |
| Abstract | Alterations in inhibitory (GABA) neurons, including deficiencies in the GABA synthesizing enzyme GAD67, in the prefrontal cortex in schizophrenia are pronounced in the subpopulations of neurons that contain the calcium-binding protein parvalbumin or the neuropeptide somatostatin. The presence of similar illness-related deficits in the transcription factor LHX6, which regulates prenatal development of parvalbumin and somatostatin neurons, suggests that cortical GABA neuron dysfunction may be related to disturbances in utero. Since the chemokine receptors CXCR4 and CXCR7 guide the migration of cortical parvalbumin and somatostatin neurons from their birthplace in the medial ganglionic eminence to their final destination in the neocortex, we sought to determine whether altered CXCR4 and/or CXCR7 mRNA levels were associated with disturbances in GABA-related markers in schizophrenia. Quantitative PCR was used to quantify CXCR4 and CXCR7 mRNA levels in the prefrontal cortex of 62 schizophrenia and 62 healthy comparison subjects that were previously characterized for markers of parvalbumin and somatostatin neurons and in antipsychotic-exposed monkeys. We found elevated mRNA levels for CXCR7 (+29%; p<.0001) and CXCR4 (+14%, p=.052) in schizophrenia subjects but not in antipsychotic-exposed monkeys. CXCR7 mRNA levels were inversely correlated with mRNA levels for GAD67, parvalbumin, somatostatin, and LHX6 in schizophrenia but not in healthy subjects. These findings suggest that higher mRNA levels for CXCR7, and possibly CXCR4, may represent a compensatory mechanism to sustain the migration and correct positioning of cortical parvalbumin and somatostatin neurons in the face of other insults that disrupt the prenatal development of cortical GABA neurons in schizophrenia. |
| SCZ Keywords | schizophrenia |