Disruption of the non-canonical Wnt gene PRICKLE2 leads to autism-like behaviors with evidence for hippocampal synaptic dysfunction.

Autism spectrum disorders (ASDs) have been suggested to arise from abnormalities in the canonical and non-canonical Wnt signaling pathways. However, a direct connection between a human variant in a Wnt pathway gene and ASD-relevant brain pathology has not been established. Prickle2 (Pk2) is a post-synaptic non-canonical Wnt signaling protein shown to interact with post-synaptic density 95 (PSD-95). Here, we show that mice with disruption in Prickle2 display behavioral abnormalities including altered social interaction, learning abnormalities and behavioral inflexibility. Prickle2 disruption in mouse hippocampal neurons led to reductions in dendrite branching, synapse number and PSD size. Consistent with these findings, Prickle2 null neurons show decreased frequency and size of spontaneous miniature synaptic currents. These behavioral and physiological abnormalities in Prickle2 disrupted mice are consistent with ASD-like phenotypes present in other mouse models of ASDs. In 384 individuals with autism, we identified two with distinct, heterozygous, rare, non-synonymous PRICKLE2 variants (p.E8Q and p.V153I) that were shared by their affected siblings and inherited paternally. Unlike wild-type PRICKLE2, the PRICKLE2 variants found in ASD patients exhibit deficits in morphological and electrophysiological assays. These data suggest that these PRICKLE2 variants cause a critical loss of PRICKLE2 function. The data presented here provide new insight into the biological roles of Prickle2, its behavioral importance, and suggest disruptions in non-canonical Wnt genes such as PRICKLE2 may contribute to synaptic abnormalities underlying ASDs.

Contribution of VANGL2 mutations to isolated neural tube defects.

Vangl2 was identified as the gene defective in the Looptail (Lp) mouse model for neural tube defects (NTDs). This gene forms part of the planar cell polarity (PCP) pathway, also called the non-canonical Frizzled/Dishevelled pathway, which mediates the morphogenetic process of convergent extension essential for proper gastrulation and neural tube formation in vertebrates. Genetic defects in PCP signaling have strongly been associated with NTDs in mouse models. To assess the role of VANGL2 in the complex etiology of NTDs in humans, we resequenced this gene in a large multi-ethnic cohort of 673 familial and sporadic NTD patients, including 453 open spina bifida and 202 closed spinal NTD cases. Six novel rare missense mutations were identified in seven patients, five of which were affected with closed spinal NTDs. This suggests that VANGL2 mutations may predispose to NTDs in approximately 2.5% of closed spinal NTDs (5 in 202), at a frequency that is significantly different from that of 0.4% (2 in 453) detected in open spina bifida patients (p = 0.027). Our findings strongly implicate VANGL2 in the genetic causation of spinal NTDs in a subset of patients and provide additional evidence for a pathogenic role of PCP signaling in these malformations.

SCARB2 mutations in progressive myoclonus epilepsy (PME) without renal failure.

OBJECTIVE: Mutations in SCARB2 were recently described as causing action myoclonus renal failure syndrome (AMRF). We hypothesized that mutations in SCARB2 might account for unsolved cases of progressive myoclonus epilepsy (PME) without renal impairment, especially those resembling Unverricht-Lundborg disease (ULD). Additionally, we searched for mutations in the PRICKLE1 gene, newly recognized as a cause of PME mimicking ULD. METHODS: We reviewed cases of PME referred for diagnosis over two decades in which a molecular diagnosis had not been reached. Patients were classified according to age of onset, clinical pattern, and associated neurological signs into "ULD-like" and "not ULD-like." After exclusion of mutations in cystatin B (CSTB), DNA was examined for sequence variation in SCARB2 and PRICKLE1. RESULTS: Of 71 cases evaluated, 41 were "ULD-like" and five had SCARB2 mutations. None of 30 "not ULD-like" cases were positive. The five patients with SCARB2 mutations had onset between 14 and 26 years of age, with no evidence of renal failure during 5.5 to 15 years of follow-up; four were followed until death. One living patient had slight proteinuria. A subset of 25 cases were sequenced for PRICKLE1 and no mutations were found. INTERPRETATION: Mutations in SCARB2 are an important cause of hitherto unsolved cases of PME resembling ULD at onset. SCARB2 should be evaluated even in the absence of renal involvement. Onset is in teenage or young adult life. Molecular diagnosis is important for counseling the patient and family, particularly as the prognosis is worse than classical ULD.

In cis autosomal dominant mutation of Senataxin associated with tremor/ataxia syndrome.

Senataxin mutations are the molecular basis of two distinct syndromes: (1) ataxia oculomotor apraxia type 2 (AOA2) and (2) juvenile amyotrophic lateral sclerosis 4 (ALS4). The authors describe clinical and molecular genetic studies of mother and daughter who display symptoms of cerebellar ataxia/atrophy, oculomotor defects, and tremor. Both patients share Senataxin mutations N603D and Q653K in cis (N603D-Q653K), adjacent to an N-terminal domain thought to function in protein-protein interaction. The N-terminal and helicase domains appear to harbor missense mutation clusters associated with AOA2 and ALS4. Working synergistically, the N603D-Q653K mutations may confer a partial dominant negative effect, acting on the senataxin N-terminal, further expanding the phenotypic spectrum associated with Senataxin mutations.

Whole genomewide linkage screen for neural tube defects reveals regions of interest on chromosomes 7 and 10.

Neural tube defects (NTDs) are the second most common birth defects (1 in 1000 live births) in the world. Periconceptional maternal folate supplementation reduces NTD risk by 50-70%; however, studies of folate related and other developmental genes in humans have failed to definitively identify a major causal gene for NTD. The aetiology of NTDs remains unknown and both genetic and environmental factors are implicated. We present findings from a microsatellite based screen of 44 multiplex pedigrees ascertained through the NTD Collaborative Group. For the linkage analysis, we defined our phenotype narrowly by considering individuals with a lumbosacral level myelomeningocele as affected, then we expanded the phenotype to include all types of NTDs. Two point parametric analyses were performed using VITESSE and HOMOG. Multipoint parametric and nonparametric analyses were performed using ALLEGRO. Initial results identified chromosomes 7 and 10, both with maximum parametric multipoint lod scores (Mlod) >2.0. Chromosome 7 produced the highest score in the 24 cM interval between D7S3056 and D7S3051 (parametric Mlod 2.45; nonparametric Mlod 1.89). Further investigation demonstrated that results on chromosome 7 were being primarily driven by a single large pedigree (parametric Mlod 2.40). When this family was removed from analysis, chromosome 10 was the most interesting region, with a peak Mlod of 2.25 at D10S1731. Based on mouse human synteny, two candidate genes (Meox2, Twist1) were identified on chromosome 7. A review of public databases revealed three biologically plausible candidates (FGFR2, GFRA1, Pax2) on chromosome 10. The results from this screen provide valuable positional data for prioritisation of candidate gene assessment in future studies of NTDs.

Expression pattern of the Ets-related transcription factor Elf-1.

Members of the Ets family of winged helix-loop-helix transcription factors play important roles in the development and function of multiple mammalian cell lineages. Elf-1 is an Ets-related transcription factor that is expressed at high levels in T cells and is known to regulate the expression of several T cell genes, including the granulocyte-macrophage colony stimulating factor (GM-CSF) gene, the interleukin-2 receptor alpha subunit (IL-2Ralpha) gene, and the CD4 gene. In the studies described in this report, we have characterized the pattern of expression of Elf-1 in the developing mouse embryo and in adult mouse tissues as well as in multiple immortalized human and murine cell lines. Elf-1 is expressed at high levels throughout thymocyte development, with equivalent levels of Elf-1 expression seen in all subsets of maturing thymocytes and T cells. Somewhat surprisingly, however, Elf-1 is also expressed at high levels in epithelial cells lining the oral cavity, the lung, the CNS, and the gastrointestinal and urinary tracts as well as in the skin of the developing mouse embryo and at lower levels in the adult mouse testis and liver. Western blot analyses of a large number of immortalized cell lines demonstrated high-level Elf-1 expression in T and B lymphocyte and macrophage cell lines as well as in two prostate carcinoma cell lines. Low-level expression was observed in fibroblasts, embryonic stem cells, and myoblasts. Taken together, our data suggest that in addition to its role in regulating T cell development and function, Elf-1 may regulate gene expression in the B cell and myelomonocytic lineages, as well as in multiple epithelial cell types during murine embryonic development.

Physical interactions between Ets and NF-kappaB/NFAT proteins play an important role in their cooperative activation of the human immunodeficiency virus enhancer in T cells.

The transcriptional regulatory elements of many inducible T-cell genes contain adjacent or overlapping binding sites for the Ets and NF-kappaB/NFAT families of transcription factors. Similar arrays of functionally important NF-kappaB/NFAT and Ets binding sites are present in the transcriptional enhancers of human immunodeficiency viruses types 1 and 2 (HIV-1 and HIV-2), suggesting that this pattern of nuclear protein binding sites reflects an evolutionarily conserved mechanism for regulating inducible T-cell gene expression that has been co-opted during HIV evolution. Despite these findings, the molecular mechanisms by which Ets and NF-kappaB/NFAT proteins cooperatively regulate inducible T-cell gene expression remained unknown. In the studies described in this report, we demonstrated a physical interaction between multiple Ets and NF-kappaB/NFAT proteins both in vitro and in activated normal human T cells. This interaction is mediated by the Ets domain of Ets proteins and the C-terminal region of the Rel homology domains of NF-kappaB/NFAT proteins. In addition, the Ets-NF-kappaB/NFAT interaction requires the presence of DNA binding sites for both proteins, as it is abolished by the DNA intercalating agents propidium iodide and ethidium bromide and enhanced by the presence of synthetic oligonucleotides containing binding sites for Ets and NF-kappaB proteins. A dominant-negative mutant of NF-kappaB p50 that binds DNA but fails to interact with Ets proteins inhibits the synergistic activation of the HIV-1 and HIV-2 enhancers by NF-kappaB (p50 + p65) and Ets-1, suggesting that physical interaction between Ets and NF-kappaB proteins is required for the transcriptional activity of the HIV-1 and HIV-2 enhancers. Taken together, these findings suggest that evolutionarily conserved physical interactions between Ets and NF-kappaB/NFAT proteins are important in regulating the inducible expression of T-cell genes and viruses. These interactions represent a potential target for the development of novel immunosuppressive and antiviral therapies.

A direct physical association between ETS and AP-1 transcription factors in normal human T cells.

The Ets and AP-1 families of transcription factors bind distinct DNA elements and subserve diverse functions in multiple lymphoid and nonlymphoid cell types. Functionally important Ets and AP-1 binding sites have been identified in a large number of enhancer elements, suggesting important cooperative interactions between these two families of transcription factors. In this report, we have demonstrated a direct physical interaction between Ets and AP-1 proteins both in vitro and in activated human T cells. This interaction is mediated by the binding of the basic domain of Jun to the Ets domain of Ets proteins. Jun, in association with Ets, is capable of interacting with Fos family members to form a trimolecular protein complex. The physical association between Ets-1 and AP-1 proteins is required for the transcriptional activity of enhancer elements containing adjacent Ets and AP-1 binding sites. We conclude that direct physical interactions between Ets and AP-1 transcription factors play an important role in regulating mammalian gene expression.

Activation of the granulocyte-macrophage colony-stimulating factor promoter in T cells requires cooperative binding of Elf-1 and AP-1 transcription factors.

The granulocyte-macrophage colony-stimulating factor (GM-CSF) gene has been studied extensively as a model system of transcriptional induction during T-lymphocyte activation. The GM-CSF gene is not expressed in resting peripheral blood T cells but is rapidly induced at the transcriptional level following activation through the cell surface T-cell receptor. A highly conserved 19-bp element located immediately 5' of the human GM-CSF TATA box (bp -34 to -52), herein called purine box 1 (PB1), has been shown to bind a T-cell nuclear protein complex and to be required for transcriptional induction of the GM-CSF gene following T-cell activation. The PB1 sequence motif is highly conserved in both human and murine GM-CSF genes. In this report, we demonstrate that the PB1 element alone confers inducibility on a heterologous promoter following transfection into human Jurkat T cells. In addition, we identify a major PB1 nuclear protein-binding complex that is not present in resting peripheral blood T cells but is rapidly induced following T-cell activation. Sequence analysis revealed that PB1 is composed of adjacent binding sites for Ets and AP-1 transcription factors. In vitro mutagenesis experiments demonstrated that both the Ets and AP-1 sites are required for binding of the inducible PB1 nuclear protein complex and for the transcriptional activity of this element and the GM-CSF promoter in activated T cells. Using antibodies specific for different Ets and AP-1 family members, we demonstrate that the major inducible PB1-binding activity present in activated T-cell nuclear extracts is composed of the Elf-1, c-Fos, and JunB transcription factors. Taken together, these results suggest that cooperative interactions between specific Ets and AP-1 family members are important in regulating inducible gene expression following T-cell activation.