Expression patterns of the three Teashirt-related genes define specific boundaries in the developing and postnatal mouse forebrain

Cell-type profiling in salamanders identifies innovations in vertebrate forebrain evolution

The evolution of advanced cognition in vertebrates is associated with two independent innovations in the forebrain: the six-layered neocortex in mammals and the dorsal ventricular ridge (DVR) in sauropsids (reptiles and birds). How these innovations arose in vertebrate ancestors remains unclear. To reconstruct forebrain evolution in tetrapods, we built a cell-type atlas of the telencephalon of the salamander Pleurodeles waltl. Our molecular, developmental, and connectivity data indicate that parts of the sauropsid DVR trace back to tetrapod ancestors. By contrast, the salamander dorsal pallium is devoid of cellular and molecular characteristics of the mammalian neocortex yet shares similarities with the entorhinal cortex and subiculum. Our findings chart the series of innovations that resulted in the emergence of the mammalian six-layered neocortex and the sauropsid DVR.

Targeted Tshz3 deletion in corticostriatal circuit components segregates core autistic behaviors

We previously linked TSHZ3 haploinsufficiency to autism spectrum disorder (ASD) and showed that embryonic or postnatal Tshz3 deletion in mice results in behavioral traits relevant to the two core domains of ASD, namely social interaction deficits and repetitive behaviors. Here, we provide evidence that cortical projection neurons (CPNs) and striatal cholinergic interneurons (SCINs) are two main and complementary players in the TSHZ3-linked ASD syndrome. In the cerebral cortex, TSHZ3 is expressed in CPNs and in a proportion of GABAergic interneurons, but not in cholinergic interneurons or glial cells. In the striatum, TSHZ3 is expressed in all SCINs, while its expression is absent or partial in the other main brain cholinergic systems. We then characterized two new conditional knockout (cKO) models generated by crossing Tshz3^flox/flox with Emx1-Cre (Emx1-cKO) or Chat-Cre (Chat-cKO) mice to decipher the respective role of CPNs and SCINs. Emx1-cKO mice show altered excitatory synaptic transmission onto CPNs and impaired plasticity at corticostriatal synapses, with neither cortical neuron loss nor abnormal layer distribution. These animals present social interaction deficits but no repetitive patterns of behavior. Chat-cKO mice exhibit no loss of SCINs but changes in the electrophysiological properties of these interneurons, associated with repetitive patterns of behavior without social interaction deficits. Therefore, dysfunction in either CPNs or SCINs segregates with a distinct ASD behavioral trait. These findings provide novel insights onto the implication of the corticostriatal circuitry in ASD by revealing an unexpected neuronal dichotomy in the biological background of the two core behavioral domains of this disorder.

Temporally Distinct Roles for the Zinc Finger Transcription Factor Sp8 in the Generation and Migration of Dorsal Lateral Ganglionic Eminence (dLGE)-Derived Neuronal Subtypes in the Mouse

Progenitors in the dorsal lateral ganglionic eminence (dLGE) are known to give rise to olfactory bulb (OB) interneurons and intercalated cells (ITCs) of the amygdala. The dLGE enriched transcription factor Sp8 is required for the normal generation of ITCs as well as OB interneurons, particularly the calretinin (CR)-expressing subtype. In this study, we used a genetic gain-of-function approach in mice to examine the roles Sp8 plays in controlling the development of dLGE-derived neuronal subtypes. Misexpression of Sp8 throughout the ventral telencephalic subventricular zone (SVZ) from early embryonic stages, led to an increased generation of ITCs which was dependent on Tshz1 gene dosage. Additionally, Sp8 misexpression impaired rostral migration of OB interneurons with clusters of CR interneurons seen in the SVZ along with decreased differentiation of calbindin OB interneurons. Sp8 misexpression throughout the ventral telencephalon also reduced ventral LGE neuronal subtypes including striatal projection neurons. Delaying Sp8 misexpression until E14-15 rescued the striatal and amygdala phenotypes but only partially rescued OB interneuron reductions, consistent with an early window of striatal and amygdala neurogenesis and ongoing OB interneuron generation at this late stage. Our results demonstrate critical roles for the timing and neuronal cell-type specificity of Sp8 expression in mouse LGE neurogenesis.

A Genetically Defined Compartmentalized Striatal Direct Pathway for Negative Reinforcement

The striosome compartment within the dorsal striatum has been implicated in reinforcement learning and regulation of motivation, but how striosomal neurons contribute to these functions remains elusive. Here, we show that a genetically identified striosomal population, which expresses the Teashirt family zinc finger 1 (Tshz1) and belongs to the direct pathway, drives negative reinforcement and is essential for aversive learning in mice. Contrasting a "conventional" striosomal direct pathway, the Tshz1 neurons cause aversion, movement suppression, and negative reinforcement once activated, and they receive a distinct set of synaptic inputs. These neurons are predominantly excited by punishment rather than reward and represent the anticipation of punishment or the motivation for avoidance. Furthermore, inhibiting these neurons impairs punishment-based learning without affecting reward learning or movement. These results establish a major role of striosomal neurons in behaviors reinforced by punishment and moreover uncover functions of the direct pathway unaccounted for in classic models.

Construct Validity and Cross Validity of a Test Battery Modeling Autism Spectrum Disorder (ASD) in Mice

Modeling in other organism species is one of the crucial stages in ascertaining the association between gene and psychiatric disorder. Testing Autism Spectrum Disorder (ASD) in mice is very popular but construct validity of the batteries is not available. We presented here the first factor analysis of a behavioral model of ASD-like in mice coupled with empirical validation. We defined fourteen measures aligning mouse-behavior measures with the criteria defined by DSM-5 for the diagnostic of ASD. Sixty-five mice belonging to a heterogeneous pool of genotypes were tested. Reliability coefficients vary from .68 to .81. The factor analysis resulted in a three- factor solution in line with DSM criteria: social behavior, stereotypy and narrowness of the field of interest. The empirical validation with mice sharing a haplo-insufficiency of the zinc-finger transcription factor TSHZ3/Tshz3 associated with ASD shows the discriminant power of the highly loaded items.

Teashirt 1 (Tshz1) is essential for the development, survival and function of hypoglossal and phrenic motor neurons in mouse

Feeding and breathing are essential motor functions and rely on the activity of hypoglossal and phrenic motor neurons that innervate the tongue and diaphragm, respectively. Little is known about the genetic programs that control the development of these neuronal subtypes. The transcription factor Tshz1 is strongly and persistently expressed in developing hypoglossal and phrenic motor neurons. We used conditional mutation of Tshz1 in the progenitor zone of motor neurons (Tshz1^{MN Δ}) to show that Tshz1 is essential for survival and function of hypoglossal and phrenic motor neurons. Hypoglossal and phrenic motor neurons are born in correct numbers, but many die between embryonic day 13.5 and 14.5 in Tshz1^{MN Δ} mutant mice. In addition, innervation and electrophysiological properties of phrenic and hypoglossal motor neurons are altered. Severe feeding and breathing problems accompany this developmental deficit. Although motor neuron survival can be rescued by elimination of the pro-apoptotic factor Bax, innervation, feeding and breathing defects persist in Bax^-/-; Tshz1^{MN Δ} mutants. We conclude that Tshz1 is an essential transcription factor for the development and physiological function of phrenic and hypoglossal motor neurons.

Postnatal Tshz3 Deletion Drives Altered Corticostriatal Function and Autism Spectrum Disorder-like Behavior

BACKGROUND

Heterozygous deletion of the TSHZ3 gene, encoding for the teashirt zinc-finger homeobox family member 3 (TSHZ3) transcription factor that is highly expressed in cortical projection neurons (CPNs), has been linked to an autism spectrum disorder (ASD) syndrome. Similarly, mice with Tshz3 haploinsufficiency show ASD-like behavior, paralleled by molecular changes in CPNs and corticostriatal synaptic dysfunctions. Here, we aimed at gaining more insight into "when" and "where" TSHZ3 is required for the proper development of the brain, and its deficiency crucial for developing this ASD syndrome.

METHODS

We generated and characterized a novel mouse model of conditional Tshz3 deletion, obtained by crossing Tshz3^flox/flox with CaMKIIalpha-Cre mice, in which Tshz3 is deleted in CPNs from postnatal day 2 to 3 onward. We characterized these mice by a multilevel approach combining genetics, cell biology, electrophysiology, behavioral testing, and bioinformatics.

RESULTS

These conditional Tshz3 knockout mice exhibit altered cortical expression of more than 1000 genes, ∼50% of which have their human orthologue involved in ASD, in particular genes encoding for glutamatergic synapse components. Consistently, we detected electrophysiological and synaptic changes in CPNs and impaired corticostriatal transmission and plasticity. Furthermore, these mice showed strong ASD-like behavioral deficits.

CONCLUSIONS

Our study reveals a crucial postnatal role of TSHZ3 in the development and functioning of the corticostriatal circuitry and provides evidence that dysfunction in these circuits might be determinant for ASD pathogenesis. Our conditional Tshz3 knockout mouse constitutes a novel ASD model, opening the possibility for an early postnatal therapeutic window for the syndrome linked to TSHZ3 haploinsufficiency.

Postnatal developmental dynamics of cell type specification genes in Brn3a/Pou4f1 Retinal Ganglion Cells

BACKGROUND

About 20-30 distinct Retinal Ganglion Cell (RGC) types transmit visual information from the retina to the brain. The developmental mechanisms by which RGCs are specified are still largely unknown. Brn3a is a member of the Brn3/Pou4f transcription factor family, which contains key regulators of RGC postmitotic specification. In particular, Brn3a ablation results in the loss of RGCs with small, thick and dense dendritic arbors ('midget-like' RGCs), and morphological changes in other RGC subpopulations. To identify downstream molecular mechanisms underlying Brn3a effects on RGC numbers and morphology, our group recently performed a RNA deep sequencing screen for Brn3a transcriptional targets in mouse RGCs and identified 180 candidate transcripts.

METHODS

We now focus on a subset of 28 candidate genes encoding potential cell type determinant proteins. We validate and further define their retinal expression profile at five postnatal developmental time points between birth and adult stage, using in situ hybridization (ISH), RT-PCR and fluorescent immunodetection (IIF).

RESULTS

We find that a majority of candidate genes are enriched in the ganglion cell layer during early stages of postnatal development, but dynamically change their expression profile. We also document transcript-specific expression differences for two example candidates, using RT-PCR and ISH. Brn3a dependency could be confirmed by ISH and IIF only for a fraction of our candidates.

CONCLUSIONS

Amongst our candidate Brn3a target genes, a majority demonstrated ganglion cell layer specificity, however only around two thirds showed Brn3a dependency. Some were previously implicated in RGC type specification, while others have known physiological functions in RGCs. Only three genes were found to be consistently regulated by Brn3a throughout postnatal retina development - Mapk10, Tusc5 and Cdh4.

Loss of Intercalated Cells (ITCs) in the Mouse Amygdala of Tshz1 Mutants Correlates with Fear, Depression, and Social Interaction Phenotypes

The intercalated cells (ITCs) of the amygdala have been shown to be critical regulatory components of amygdalar circuits, which control appropriate fear responses. Despite this, the molecular processes guiding ITC development remain poorly understood. Here we establish the zinc finger transcription factor Tshz1 as a marker of ITCs during their migration from the dorsal lateral ganglionic eminence through maturity. Using germline and conditional knock-out (cKO) mouse models, we show that Tshz1 is required for the proper migration and differentiation of ITCs. In the absence of Tshz1, migrating ITC precursors fail to settle in their stereotypical locations encapsulating the lateral amygdala and BLA. Furthermore, they display reductions in the ITC marker Foxp2 and ectopic persistence of the dorsal lateral ganglionic eminence marker Sp8. Tshz1 mutant ITCs show increased cell death at postnatal time points, leading to a dramatic reduction by 3 weeks of age. In line with this, Foxp2-null mutants also show a loss of ITCs at postnatal time points, suggesting that Foxp2 may function downstream of Tshz1 in the maintenance of ITCs. Behavioral analysis of male Tshz1 cKOs revealed defects in fear extinction as well as an increase in floating during the forced swim test, indicative of a depression-like phenotype. Moreover, Tshz1 cKOs display significantly impaired social interaction (i.e., increased passivity) regardless of partner genetics. Together, these results suggest that Tshz1 plays a critical role in the development of ITCs and that fear, depression-like and social behavioral deficits arise in their absence.SIGNIFICANCE STATEMENT We show here that the zinc finger transcription factor Tshz1 is expressed during development of the intercalated cells (ITCs) within the mouse amygdala. These neurons have previously been shown to play a crucial role in fear extinction. Tshz1 mouse mutants exhibit severely reduced numbers of ITCs as a result of abnormal migration, differentiation, and survival of these neurons. Furthermore, the loss of ITCs in mouse Tshz1 mutants correlates well with defects in fear extinction as well as the appearance of depression-like and abnormal social interaction behaviors reminiscent of depressive disorders observed in human patients with distal 18q deletions, including the Tshz1 locus.

Modulation of Neurogenesis through the Promotion of Energy Production Activity Is behind the Antidepressant-Like Effect of Colonial Green Alga, Botryococcus braunii

Algae have been recognized as important resources providing functional components due to their capacity to exert beneficial effects on health. Therefore, there is increasing interest in investigating the biological activity of algae. In this study, we evaluated the antidepressant-like effect of the administration of 100 mg/kg/day of the ethanol extract of colonial green alga Botryococcus braunii (EEB) for 14 consecutive days in the forced swimming test (FST)-induced depression in imprinting control region (ICR) mice. Imipramine, a commercial antidepressant drug, was used as a positive control. In addition, we investigated the molecular mechanisms underlying the effect of EEB by measuring ATP production and by assessing any change in gene expression at the end of the treatment using real-time polymerase chain reaction (PCR) and microarray assays. We showed that the immobility time in the water-administered control (FST stress) group gradually increased from day 1 to day 14. However, treatment with EEB caused a significant decrease of immobility time in the FST compared with that in the FST stress group. Microarray and real-time PCR results revealed that EEB treatment induced variation in the expression of several genes associated with neurogenesis, energy metabolism, and dopamine synthesis. Interestingly, we revealed that only EEB treatment enhanced the promotion of energy production, while treatment with imipramine was ineffective. Our study provides the first evidence that B. braunii enhances energy production, which may contribute to the modulation of neurogenesis and to the enhancement of dopaminergic function, in turn potentially underlying the antistress- and antidepressant-like effects that we observed.

Characterization of Glcci1 expression in a subpopulation of lateral ganglionic eminence progenitors in the mouse telencephalon

BACKGROUND

The lateral ganglionic eminence (LGE) in the ventral telencephalon is a diverse progenitor domain subdivided by distinct gene expression into a dorsal region (dLGE) that gives rise to olfactory bulb and amygdalar interneurons and a ventral region (vLGE) that gives rise to striatal projection neurons. The homeobox gene, Gsx2, is an enriched marker of the LGE and is expressed in a high dorsal to low ventral gradient in the ventricular zone (VZ) as development proceeds. Aside from Gsx2, markers restricted to the VZ in the dLGE and/or vLGE remain largely unknown.

RESULTS

Here, we show that the gene and protein expression of Glucocorticoid-induced transcript 1 (Glcci1) has a similar dorsal to ventral gradient of expression in the VZ as Gsx2. We found that Glcci1 gene and protein expression are reduced in Gsx2 mutants, and are increased in the cortex after early and late Gsx2 misexpression. Moreover, Glcci1 expressing cells are restricted to a subpopulation of Gsx2 positive cells on the basal side of the VZ and co-express Ascl1, but not the subventricular zone dLGE marker, Sp8.

CONCLUSIONS

These findings suggest that Glcci1 is a new marker of a subpopulation of LGE VZ progenitor cells in the Gsx2 lineage. Developmental Dynamics 247:222-228, 2018. © 2017 Wiley Periodicals, Inc.

Integrated analysis identified an intestinal-like and a diffuse-like gene sets that predict gastric cancer outcome

The two major histological types of gastric cancer, intestinal and diffuse subtypes, have distinct epidemiological and pathophysiological features and were also suggested to be of diverse clinical outcomes. Although the gene expression spectrum of gastric cancer subtypes has been reported by previous studies, its linkage with gastric cancer clinical features and outcomes remains elusive. We investigated large-sample online gastric cancer datasets for seeking genes correlated with the clinical diversities between gastric cancer intestinal and diffuse subtypes. Genes differently expressed between the two subtypes were assessed by multiple statistical analysis and were testified on cellular level by quantitative RT-PCR. Related genes were combined to generate a risk signature, and their mutual linkages were also explored. Among genes overexpressed in intestinal subtype, ATPIF1, PRDX2, PRKAR2A, and SMC1A were correlated with positive prognosis. Among genes overexpressed in diffuse subtype, DTNA, GPR161, IDS, RHOQ, and TSHZ2 were correlated with negative prognosis. These nine genes were all novel independent prognostic factors. When used in combination as signatures, these two gene sets displayed strong efficacy for prediction of the prognosis and clinical variables in gastric and colorectal cancer. Hence, these two genes sets were respectively defined as the favorable intestinal-like and adverse diffuse-like gene sets. We identified nine novel genes correlated with the clinical diversity between the intestinal and diffuse subtypes of gastric cancer. The malignant changes from the intestinal to diffuse subtype might be due to the reduction of the four intestinal-like genes, as well as the elevation of the five diffuse-like genes.

TSHZ3 deletion causes an autism syndrome and defects in cortical projection neurons

TSHZ3, which encodes a zinc-finger transcription factor, was recently positioned as a hub gene in a module of the genes with the highest expression in the developing human neocortex, but its functions remained unknown. Here we identify TSHZ3 as the critical region for a syndrome associated with heterozygous deletions at 19q12-q13.11, which includes autism spectrum disorder (ASD). In Tshz3-null mice, differentially expressed genes include layer-specific markers of cerebral cortical projection neurons (CPNs), and the human orthologs of these genes are strongly associated with ASD. Furthermore, mice heterozygous for Tshz3 show functional changes at synapses established by CPNs and exhibit core ASD-like behavioral abnormalities. These findings highlight essential roles for Tshz3 in CPN development and function, whose alterations can account for ASD in the newly defined TSHZ3 deletion syndrome.

TSHZ1-dependent gene regulation is essential for olfactory bulb development and olfaction

The olfactory bulb (OB) receives odor information from the olfactory epithelium and relays this to the olfactory cortex. Using a mouse model, we found that development and maturation of OB interneurons depends on the zinc finger homeodomain factor teashirt zinc finger family member 1 (TSHZ1). In mice lacking TSHZ1, neuroblasts exhibited a normal tangential migration to the OB; however, upon arrival to the OB, the neuroblasts were distributed aberrantly within the radial dimension, and many immature neuroblasts failed to exit the rostral migratory stream. Conditional deletion of Tshz1 in mice resulted in OB hypoplasia and severe olfactory deficits. We therefore investigated olfaction in human subjects from families with congenital aural atresia that were heterozygous for TSHZ1 loss-of-function mutations. These individuals displayed hyposmia, which is characterized by impaired odor discrimination and reduced olfactory sensitivity. Microarray analysis, in situ hybridization, and ChIP revealed that TSHZ1 bound to and regulated expression of the gene encoding prokineticin receptor 2 (PROKR2), a G protein–coupled receptor essential for OB development. Mutations in PROKR2 lead to Kallmann syndrome, characterized by anosmia and hypogonadotrophic hypogonadism. Our data indicate that TSHZ1 is a key regulator of mammalian OB development and function and controls the expression of molecules involved in human Kallmann syndrome.

TSHZ3 and SOX9 regulate the timing of smooth muscle cell differentiation in the ureter by reducing myocardin activity

Smooth muscle cells are of key importance for the proper functioning of different visceral organs including those of the urogenital system. In the mouse ureter, the two transcriptional regulators TSHZ3 and SOX9 are independently required for initiation of smooth muscle differentiation from uncommitted mesenchymal precursor cells. However, it has remained unclear whether TSHZ3 and SOX9 act independently or as part of a larger regulatory network. Here, we set out to characterize the molecular function of TSHZ3 in the differentiation of the ureteric mesenchyme. Using a yeast-two-hybrid screen, we identified SOX9 as an interacting protein. We show that TSHZ3 also binds to the master regulator of the smooth muscle program, MYOCD, and displaces it from the coregulator SRF, thereby disrupting the activation of smooth muscle specific genes. We found that the initiation of the expression of smooth muscle specific genes in MYOCD-positive ureteric mesenchyme coincides with the down regulation of Sox9 expression, identifying SOX9 as a possible negative regulator of smooth muscle cell differentiation. To test this hypothesis, we prolonged the expression of Sox9 in the ureteric mesenchyme in vivo. We found that Sox9 does not affect Myocd expression but significantly reduces the expression of MYOCD/SRF-dependent smooth muscle genes, suggesting that down-regulation of Sox9 is a prerequisite for MYOCD activity. We propose that the dynamic expression of Sox9 and the interaction between TSHZ3, SOX9 and MYOCD provide a mechanism that regulates the pace of progression of the myogenic program in the ureter.

Teashirt-3, a novel regulator of muscle differentiation, associates with BRG1-associated factor 57 (BAF57) to inhibit myogenin gene expression

In adult muscles and under normal physiological conditions, satellite cells are found in a quiescent state but can be induced to enter the cell cycle by signals resulting from exercise, injury-induced muscle regeneration, or specific disease states. Once activated, satellite cells proliferate, self-renew, and differentiate to form myofibers. In the present study, we found that the zinc finger-containing factor Teashirt-3 (TSHZ3) was expressed in quiescent satellite cells of adult mouse skeletal muscles. We showed that following treatment with cardiotoxin TSHZ3 was strongly expressed in satellite cells of regenerating muscles. Moreover, immunohistochemical analysis indicated that TSHZ3 was expressed in both quiescent and activated satellite cells on intact myofibers in culture. TSHZ3 expression was maintained in myoblasts but disappeared with myotube formation. In C2C12 myoblasts, we showed that overexpression of Tshz3 impaired myogenic differentiation and promoted the down-regulation of myogenin (Myog) and up-regulation of paired-box factor 7 (Pax7). Moreover, knockdown experiments revealed a selective effect of Tshz3 on Myog regulation, and transcriptional reporter experiments indicated that TSHZ3 repressed Myog promoter. We identified the BRG1-associated factor 57 (BAF57), a subunit of the SWI/SNF complex, as a partner of TSHZ3. We showed that TSHZ3 cooperated with BAF57 to repress MYOD-dependent Myog expression. These results suggest a novel mechanism for transcriptional repression by TSHZ3 in which TSHZ3 and BAF57 cooperate to modulate MyoD activity on the Myog promoter to regulate skeletal muscle differentiation.

Rare and frequent promoter methylation, respectively, of TSHZ2 and 3 genes that are both downregulated in expression in breast and prostate cancers

Background

Neoplastic cells harbor both hypomethylated and hypermethylated regions of DNA. Whereas hypomethylation is found mainly in repeat sequences, regional hypermethylation has been linked to the transcriptional silencing of certain tumor suppressor genes. We attempted to search for candidate genes involved in breast/prostate carcinogenesis, using the criteria that they should be expressed in primary cultures of normal breast/prostate epithelial cells but are frequently downregulated in breast/prostate cancer cell lines and that their promoters are hypermethylated.

Methodology/Principal Findings

We identified several dozens of candidates among 194 homeobox and related genes using Systematic Multiplex RT-PCR and among 23,000 known genes and 23,000 other expressed sequences in the human genome by DNA microarray hybridization. An additional examination, by real-time qRT-PCR of clinical specimens of breast cancer, further narrowed the list of the candidates. Among them, the most frequently downregulated genes in tumors were NP_775756 and ZNF537, from the homeobox gene search and the genome-wide search, respectively. To our surprise, we later discovered that these genes belong to the same gene family, the 3-member Teashirt family, bearing the new names of TSHZ2 and TSHZ3. We subsequently determined the methylation status of their gene promoters. The TSHZ3 gene promoter was found to be methylated in all the breast/prostate cancer cell lines and some of the breast cancer clinical specimens analyzed. The TSHZ2 gene promoter, on the other hand, was unmethylated except for the MDA-MB-231 breast cancer cell line. The TSHZ1 gene was always expressed, and its promoter was unmethylated in all cases.

Conclusions/Significance

TSHZ2 and TSHZ3 genes turned out to be the most interesting candidates for novel tumor suppressor genes. Expression of both genes is downregulated. However, differential promoter methylation suggests the existence of distinctive mechanisms of transcriptional inactivation for these genes.

Teashirt 3 regulates development of neurons involved in both respiratory rhythm and airflow control

Neonatal breathing in mammals involves multiple neuronal circuits, but its genetic basis remains unclear. Mice deficient for the zinc finger protein Teashirt 3 (TSHZ3) fail to breathe and die at birth. Tshz3 is expressed in multiple areas of the brainstem involved in respiration, including the pre-Bötzinger complex (preBötC), the embryonic parafacial respiratory group (e-pF), and cranial motoneurons that control the upper airways. Tshz3 inactivation led to pronounced cell death of motoneurons in the nucleus ambiguus and induced strong alterations of rhythmogenesis in the e-pF oscillator. In contrast, the preBötC oscillator appeared to be unaffected. These deficits result in impaired upper airway function, abnormal central respiratory rhythm generation, and altered responses to pH changes. Thus, a single gene, Tshz3, controls the development of diverse components of the circuitry required for breathing.

Developmental origin of the neuronal subtypes that comprise the amygdalar fear circuit in the mouse

We have taken a genetic-based fate-mapping approach to determine the specific contributions of telencephalic progenitors to the structures that comprise the amygdalar fear circuit including the central (CA), lateral (LA), and basolateral (BLA) amygdala. Our data indicate that progenitors in the ventral pallium (VP) contribute projection neurons to the LA and BLA but not the CA. Rather, the CA appears to derive, at least in part, from progenitors located in the ventral lateral ganglionic eminence (vLGE). Diverse groups of interneurons populate these amygdalar nuclei, and as predicted our data support the notion that they originate from subpallial progenitors. A rather specific population of amygdalar interneurons, the intercalated cells (ITCs), is known to play a fundamental role in fear-related behaviors. However, no information on their specific origin has, as yet, been provided. Our findings suggest that the ITCs arise from the dorsal lateral ganglionic eminence (dLGE) and migrate in the lateral migratory stream to populate the paracapsular regions as well as the main intercalated mass of the amygdala (IA). Germ-line Gsx2 mutants are known to exhibit an expansion of the VP into the LGE and a concomitant reduction in the dLGE and vLGE. Accordingly, Gsx2 conditional mutants display a significantly enlarged LA and a significant reduction in ITCs both within the paracapsular regions and the IA. Additional support for a dLGE origin of the ITCs was obtained in conditional mutants of the dLGE gene Sp8. Thus, our findings indicate diverse origins for the neuronal components that comprise the amygdalar fear circuit.

Zbtb20 is essential for the specification of CA1 field identity in the developing hippocampus

The development of hippocampal circuitry depends on the proper assembly of correctly specified and fully differentiated hippocampal neurons. Little is known about factors that control the hippocampal specification. Here, we show that zinc finger protein Zbtb20 is essential for the specification of hippocampal CA1 field identity. We found that Zbtb20 expression was initially activated in the hippocampal anlage at the onset of corticogenesis, and persisted in immature hippocampal neurons. Targeted deletion of Zbtb20 in mice did not compromise the progenitor proliferation in the hippocampal and adjacent transitional ventricular zone, but led to the transformation of the hippocampal CA1 field into a transitional neocortex-like structure, as evidenced by cytoarchitectural, neuronal migration, and gene expression phenotypes. Correspondingly, the subiculum was ectopically located adjacent to the CA3 in mutant. Although the field identities of the mutant CA3 and dentate gyrus (DG) were largely maintained, their projections were severely impaired. The hippocampus of Zbtb20 null mice was reduced in size, and exhibited increased apoptotic cell death during postnatal development. Our data establish an essential role of Zbtb20 in the specification of CA1 field identity by repressing adjacent transitional neocortex-specific fate determination.

DNA copy numbers profiles in affinity-purified ovarian clear cell carcinoma

PURPOSE

Advanced ovarian clear cell carcinoma (CCC) is one of the most aggressive ovarian malignancies, in part because it tends to be resistant to platinum-based chemotherapy. At present, little is known about the molecular genetic alterations in CCCs except that there are frequent activating mutations in PIK3CA. The purpose of this study is to comprehensively define the genomic changes in CCC based on DNA copy number alterations.

EXPERIMENTAL DESIGN

We performed 250K high-density single nucleotide polymorphism array analysis in 12 affinity-purified CCCs and 10 CCC cell lines. Discrete regions of amplification and deletion were also analyzed in additional 21 affinity-purified CCCs using quantitative real-time PCR.

RESULTS

The level of chromosomal instability in CCC as defined by the extent of DNA copy number changes is similar to those previously reported in low-grade ovarian serous carcinoma but much less than those in high-grade serous carcinoma. The most remarkable region with DNA copy number gain is at chr20, which harbors a potential oncogene, ZNF217. This discrete amplicon is observed in 36% of CCCs but rarely detected in serous carcinomas regardless of grade. In addition, homozygous deletions are detected at the CDKN2A/2B and LZTS1 loci. Interestingly, the DNA copy number changes observed in fresh CCC tissues are rarely detected in the established CCC cell lines.

CONCLUSIONS

This study provides the first high resolution, genome-wide view of DNA copy number alterations in ovarian CCC. The findings provide a genomic landscape for future studies aimed at elucidating the pathogenesis and developing new target-based therapies for CCCs.

Analysis of TSHZ2 and TSHZ3 genes in congenital pelvi-ureteric junction obstruction

BACKGROUND

Congenital pelvi-ureteric junction obstruction (PUJO) affects 0.3% of human births. It may result from aberrant smooth muscle development in the renal pelvis, resulting in hydronephrosis. Mice that are null mutant for the Teashirt3 (Tshz3) gene exhibit congenital PUJO with defective smooth muscle differentiation and absent peristalsis in the proximal ureter.

METHODS

Given the phenotype of Tshz3 mutant mice, we considered that Teashirt genes, which code for a family of transcription factors, might represent candidate genes for human PUJO. To evaluate this possibility, we used in situ hydridization to analyse the three mammalian Tshz genes in mouse embryonic ureters and determined whether TSHZ3 was expressed in the human embryonic ureter. TSHZ2 and TSHZ3 were sequenced in index cases with non-syndromic PUJO.

RESULTS

Tshz2 and Tshz3 genes were detected in mouse ureters and TSHZ3 was expressed in the human embryonic renal pelvis. Direct sequencing of TSHZ2 and TSHZ3 did not identify any mutations in an initial cohort of 48 PUJO index cases, excluding these genes as a major cause of this condition. A polymorphic missense change (E469G) in TSHZ3 was identified at a residue highly conserved throughout evolution in all Teashirt proteins, although subsequently no significant difference between the E469G allele frequency in Albanian and Macedonian PUJO index cases (3.2%) versus 633 control individuals (1.7%) was found (P = 0.18).

CONCLUSIONS

Mutations in TSHZ2 and TSHZ3 are not a major cause of PUJO, at least in Albanian and Macedonian populations. Expression of these genes in the human fetal ureter emphasizes the importance of analysing these genes in other groups of patients with renal tract malformations.

Restriction of ectopic eye formation by Drosophila teashirt and tiptop to the developing antenna

In Drosophila, the retinal determination network comprises a set of nuclear factors whose loss-of-function phenotypes often include the complete or near total elimination of the developing eye. These genes also share the ability of being able to induce ectopic eye formation when forcibly expressed in nonretinal tissues such as the antennae, legs, halteres, wings, and genitals. However, it appears that the ability to redirect and transform tissue fates is limited; not all tissues and cell populations can be forced into adopting an eye fate. In this report, we demonstrate that ectopic eye formation by teashirt and its paralog tiptop, a potential new eye specification gene, is restricted to the developing antennae. Of interest, tiptop appears to be a more effective inducer of retinal formation than teashirt. A genetic screen for interacting proteins failed to identify paralog-specific relationships suggesting that the differences between these two genes may be attributed instead to structural differences between the duplicates. We also demonstrate that in addition to being expressed in coincident patterns within the developing eye, both paralogs are transcribed at very similar levels.

FE65 binds Teashirt, inhibiting expression of the primate-specific caspase-4

The Alzheimer disease (AD) amyloid protein precursor (APP) can bind the FE65 adaptor protein and this complex can regulate gene expression. We carried out yeast two-hybrid studies with a PTB domain of FE65, focusing on those genes that might be involved in nuclear signaling, and identified and validated Teashirt proteins as FE65 interacting proteins in neurons. Using reporter systems, we observed that FE65 could simultaneously recruit SET, a component of the inhibitor of acetyl transferase, and Teashirt, which in turn recruited histone deacetylases, to produce a powerful gene-silencing complex. We screened stable cell lines with a macroarray focusing on AD-related genes and identified CASP4, encoding caspase-4, as a target of this silencing complex. Chromatin immunoprecipitation showed a direct interaction of FE65 and Teashirt3 with the promoter region of CASP4. Expression studies in postmortem samples demonstrated decreasing expression of Teashirt and increasing expression of caspase-4 with progressive cognitive decline. Importantly, there were significant increases in caspase-4 expression associated with even the earliest neuritic plaque changes in AD. We evaluated a case-control cohort and observed evidence for a genetic association between the Teashirt genes TSHZ1 and TSHZ3 and AD, with the TSHZ3 SNP genotype correlating with expression of Teashirt3. The results were consistent with a model in which reduced expression of Teashirt3, mediated by genetic or other causes, increases caspase-4 expression, leading to progression of AD. Thus the cell biological, gene expression and genetic data support a role for Teashirt/caspase-4 in AD biology. As caspase-4 shows evidence of being a primate-specific gene, current models of AD and other neurodegenerative conditions may be incomplete because of the absence of this gene in the murine genome.

Teashirt 3 is necessary for ureteral smooth muscle differentiation downstream of SHH and BMP4

Ureteric contractions propel foetal urine from the kidney to the urinary bladder. Here, we show that mouse ureteric smooth muscle cell (SMC) precursors express the transcription factor teashirt 3 (TSHZ3), and that Tshz3-null mutant mice have congenital hydronephrosis without anatomical obstruction. Ex vivo, the spontaneous contractions that occurred in proximal segments of wild-type embryonic ureter explants were absent in Tshz3 mutant ureters. In vivo, prior to the onset of hydronephrosis, mutant proximal ureters failed to express contractile SMC markers, whereas these molecules were detected in controls. Mutant embryonic ureters expressed Shh and Bmp4 transcripts as normal, with appropriate expression of Ptch1 and pSMAD1/5/8 in target SM precursors, whereas myocardin, a key regulator for SMC differentiation, was not expressed in Tshz3-null ureters. In wild-type embryonic renal tract explants, exogenous BMP4 upregulated Tshz3 and myocardin expression. More interestingly, in Tshz3 mutant renal tract explants, exogenous BMP4 did not improve the Tshz3 phenotype. Thus, Tshz3 is required for proximal ureteric SMC differentiation downstream of SHH and BMP4. Furthermore, the Tshz3 mutant mouse model of ;functional' urinary obstruction resembles congenital pelvi-ureteric junction obstruction, a common human malformation, suggesting that TSHZ, or related, gene variants may contribute to this disorder.

Phylogenetic relationships among iguanian lizards using alternative partitioning methods and TSHZ1: a new phylogenetic marker for reptiles

We present phylogenetic hypotheses for the major iguanian lizard lineages and several squamate outgroups using a combined analysis of 4950 aligned base positions representing two intronless nuclear genes, TSHZ1 and RAG1. Bayesian analyses using reversible jump (RJ) mixture model selection are conducted and compared with a priori partitioned, mixed model maximum likelihood analyses. Bayesian credibility values and ML bootstraps are comparable with strong support at deep nodes and within acrodonts, but weak support for the twelve iguanid lineages. Accounting for pattern and rate heterogeneity is becoming commonplace and is essential for accurate phylogeny reconstruction.

Differential regulation of telencephalic pallial-subpallial boundary patterning by Pax6 and Gsh2

In the embryonic telencephalon, the pallial-subpallial boundary (PSB) separates the dorsal Pax6+ pallium from the ventral Gsh2+ subpallium. Previous studies have revealed that this region is a source of cells that will populate both the olfactory bulb and basal telencephalic limbic system. However, the level of progenitor cell heterogeneity and developmental genetic regulation of this progenitor region remains to be fully elucidated. In this study we carried out a comprehensive analysis of gene expression patterns at the PSB, in addition to an examination of the combinatorial function of Pax6 and Gsh2 in the specification of the PSB. First, we reveal that the PSB is comprised of a complex mix of molecularly distinct progenitor pools. In addition, by analysis of single Sey, Gsh2, and Sey/Gsh2 double mutant mice, we demonstrate that both Pax6 and Gsh2 are directly required for major aspects of PSB progenitor specification. Our analysis also reveals that the establishment of the epidermal growth factor receptor positive lateral cortical stream migratory route to the basal telencephalon is Pax6 dependent. Thus, in addition to their well-characterized cross-repressive roles in dorsal/ventral patterning our analyses reveal important novel functions of Gsh2 and Pax6 in the regulation of PSB progenitor pool specification and patterning.

Tshz1 is required for axial skeleton, soft palate and middle ear development in mice

Members of the Tshz gene family encode putative zinc fingers transcription factors that are broadly expressed during mouse embryogenesis. Tshz1 is detected from E9.5 in the somites, the spinal cord, the limb buds and the branchial arches. In order to assess the function of Tshz1 during mouse development, we generated Tshz1-deficient mice. Tshz1 inactivation leads to neonatal lethality and causes multiple developmental defects. In the craniofacial region, loss of Tshz1 function leads to specific malformations of middle ear components, including the malleus and the tympanic ring. Tshz1(-/-) mice exhibited Hox-like vertebral malformations and homeotic transformations in the cervical and thoracic regions, suggesting that Tshz1 and Hox genes are involved in common pathways to control skeletal morphogenesis. Finally, we demonstrate that Tshz1 is required for the development of the soft palate.

Cell migration along the lateral cortical stream to the developing basal telencephalic limbic system

During embryogenesis, the lateral cortical stream (LCS) emerges from the corticostriatal border (CSB), the boundary between the developing cerebral cortex and striatum. The LCS is comprised of a mix of pallial- and subpallial-derived neural progenitor cells that migrate to the developing structures of the basal telencephalon, most notably the piriform cortex and amygdala. Using a combination of in vitro and in vivo approaches, we analyzed the timing, composition, migratory modes, origin, and requirement of the homeodomain-containing transcription factor Gsh2 (genomic screened homeobox 2) in the development of this prominent migratory stream. We reveal that Pax6 (paired box gene 6)-positive pallial-derived and Dlx2 (distal-less homeobox 2)-positive subpallial-derived subpopulations of LCS cells are generated in distinct temporal windows during embryogenesis. Furthermore, our data indicate the CSB border not only is comprised of separate populations of pallial- and subpallial-derived progenitors that contribute to the LCS but also a subpopulation of cells coexpressing Pax6 and Dlx2. Moreover, despite migrating along a route outlined by a cascade of radial glia, the Dlx2-positive population appears to migrate primarily in an apparent chain-like manner, with LCS migratory cells being generated locally at the CSB with little contribution from other subpallial structures such as the medial, lateral, or caudal ganglionic eminences. We further demonstrate that the generation of the LCS is dependent on the homeodomain-containing gene Gsh2, revealing a novel requirement for Gsh2 in telencephalic development.

Teashirt 3 expression in the chick embryo reveals a remarkable association with tendon development

Drosophila teashirt (tsh) is involved in the patterning of the trunk identity together with the Hox genes. In addition, it is also a player in the Wingless and the Hedgehog pathways. In birds and mammals, three Tshz genes are identified and the expression patterns for mouse Tshz1 and Tshz2 have been reported during embryogenesis. Recently, we showed that all three mouse Tshz genes can rescue the Drosophila tsh loss-of-function phenotype, indicating that the function of the teashirt genes has been conserved during evolution. Here we describe the expression pattern of chick TSHZ3 during embryogenesis. Chick TSHZ3 is expressed in several tissues including mesodermal derivatives, the central and peripheral nervous systems. Emphasis is laid on the dynamic expression occurring in regions of the somites and limbs where tendons develop. We show that TSHZ3 is activated in the somites by FGF8, a known inducer of the tendon marker SCX.

Isolation and expression of zebrafish zinc-finger transcription factor gene tsh1

We report the expression patterns of tsh1, a zebrafish homologue of the Drosophila homeotic gene teashirt. Expression of tsh1 is first detected at the 2-somite stage (10h post-fertilization, hpf) at the anterior end of the spinal cord. Expression expands toward the posterior spinal cord, and by the prim-5 stage (24 hpf) tsh1 transcripts are detected throughout spinal cord. Between the 14- and 25-somite stage (16-24 hpf), spinal cord expression shows a clear anterior boundary at the rostral margin of rhombomere 7. Around the prim-25 stage (36 hpf), while the spinal expression of tsh1 decreases, new expression is detected in the pectoral fin buds and dorsal forebrain. By the long-pec stage (48 hpf), spinal cord expression is undetectable, but strong expression is observed in the rhombencephalon, telencephalon, tectum opticum, midbrain-hindbrain boundary, in the first pharyngeal arch and in the eyes. This expression persists at least until the larval stages. Retinoic acid signaling influences tsh1 expression. Zebrafish tsh1 expression was induced in the anterior neural tube in embryos treated briefly with exogenous retinoic acid. Furthermore, tsh1 expression was down-regulated in the spinal cord in the zebrafish neckless mutant in which RA signaling is disrupted due to a missense mutation in the gene encoding retinaldehyde dehydrogenase type 2.

Ancient duplicated conserved noncoding elements in vertebrates: a genomic and functional analysis

Fish-mammal genomic comparisons have proved powerful in identifying conserved noncoding elements likely to be cis-regulatory in nature, and the majority of those tested in vivo have been shown to act as tissue-specific enhancers associated with genes involved in transcriptional regulation of development. Although most of these elements share little sequence identity to each other, a small number are remarkably similar and appear to be the product of duplication events. Here, we searched for duplicated conserved noncoding elements in the human genome, using comparisons with Fugu to select putative cis-regulatory sequences. We identified 124 families of duplicated elements, each containing between two and five members, that are highly conserved within and between vertebrate genomes. In 74% of cases, we were able to assign a specific set of paralogous genes with annotation relating to transcriptional regulation and/or development to each family, thus removing much of the ambiguity in identifying associated genes. We find that duplicate elements have the potential to up-regulate reporter gene expression in a tissue-specific manner and that expression domains often overlap, but are not necessarily identical, between family members. Over two thirds of the families are conserved in duplicate in fish and appear to predate the large-scale duplication events thought to have occurred at the origin of vertebrates. We propose a model whereby gene duplication and the evolution of cis-regulatory elements can be considered in the context of increased morphological diversity and the emergence of the modern vertebrate body plan.