Structure-function analysis of the THAP zinc finger of THAP1, a large C2CH DNA-binding module linked to Rb/E2F pathways

Mutation of the Thap4 gene causes dwarfism and testicular anomalies in rats and mice

The petit (pet) locus is associated with dwarfism, testicular anomalies, severe thymic hypoplasia, and high postnatal lethality, which are inherited in autosomal recessive mode of inheritance in rats with a Wistar strain genetic background. Linkage analysis localized the pet locus between 98.7 Mb and 101.2 Mb on rat chromosome 9. Nucleotide sequence analysis identified 2 bp deletion in exon 2 of the Thap4 gene as the causative mutation for pet. This deletion causes a frameshift and premature termination codon, resulting in a truncated THAP4 protein lacking approximately two-thirds of the C-terminal side. Thap4 is expressed in various organs, including the testis and thymus in rats. To elucidate the biological function of THAP4 in other species, we generated Thap4 knockout mice lacking exon 2 of the Thap4 gene through genome editing. Thap4 knockout mice also exhibited dwarfism and small testis but did not show high postnatal lethality. Thymus weights of adult Thap4 knockout male mice were significantly higher compared to wild-type male mice. Although Thap4 knockout male mice were fertile, their testis contained seminiferous tubules with spermatogenesis and degenerative seminiferous tubules lacking germ cells. Additionally, we observed vacuoles in seminiferous tubules, and clusters of cells in the lumen in seminiferous tubules in Thap4 knockout male mice. These results demonstrate that spontaneous mutation of Thap4 gene in rats and knockout of Thap4 gene in mice both cause dwarfism and testicular anomalies. Thap4 gene in rats and mice is essential for normal testicular development, maintaining spermatogenesis throughout the entire region of seminiferous tubules.

DYT-THAP1: exploring gene expression in fibroblasts for potential biomarker discovery

Dystonia due to pathogenic variants in the THAP1 gene (DYT-THAP1) shows variable expressivity and reduced penetrance of ~ 50%. Since THAP1 encodes a transcription factor, modifiers influencing this variability likely operate at the gene expression level. This study aimed to assess the transferability of differentially expressed genes (DEGs) in neuronal cells related to pathogenic variants in the THAP1 gene, which were previously identified by transcriptome analyses. For this, we performed quantitative (qPCR) and Digital PCR (dPCR) in cultured fibroblasts. RNA was extracted from THAP1 manifesting (MMCs) and non-manifesting mutation carriers (NMCs) as well as from healthy controls. The expression profiles of ten of 14 known neuronal DEGs demonstrated differences in fibroblasts between these three groups. This included transcription factors and targets (ATF4, CLN3, EIF2A, RRM1, YY1), genes involved in G protein-coupled receptor signaling (BDKRB2, LPAR1), and a gene linked to apoptosis and DNA replication/repair (CRADD), which all showed higher expression levels in MMCs and NMCs than in controls. Moreover, the analysis of genes linked to neurological disorders (STXBP1, TOR1A) unveiled differences in expression patterns between MMCs and controls. Notably, the genes CUEDC2, DRD4, ECH1, and SIX2 were not statistically significantly differentially expressed in fibroblast cultures. With > 70% of the tested genes being DEGs also in fibroblasts, fibroblasts seem to be a suitable model for DYT-THAP1 research despite some restrictions. Furthermore, at least some of these DEGs may potentially also serve as biomarkers of DYT-THAP1 and influence its penetrance and expressivity.

Bioinformatic analysis of THAP9 transposase homolog: conserved regions, novel motifs

THAP9 is a transposable element-derived gene that encodes the THAP9 protein, which is homologous to the Drosophila P-element transposase (DmTNP) and can cut and paste DNA. However, the exact functional role of THAP9 is unknown. Here, we perform structure prediction, evolutionary analysis and extensive in silico characterization of THAP9, including predicting domains and putative post-translational modification sites. Comparison of the AlphaFold-predicted structure of THAP9 with the DmTNP CryoEM structure, provided insights about the C2CH motif and other DNA binding residues, RNase H-like catalytic domain and insertion domain of the THAP9 protein. We also predicted previously unreported mammalian-specific post-translational modification sites that may play a role in the subcellular localization of THAP9. Furthermore, we observed that there are distinct organism class-specific conservation patterns of key functional residues in certain THAP9 domains.

Transcriptional regulatory network for neuron-glia interactions and its implication for DYT6 dystonia

Advances in sequencing technologies have identified novel genes associated with inherited forms of dystonia, providing valuable insights into its genetic basis and revealing diverse genetic pathways and mechanisms involved in its pathophysiology. Since identifying genetic variation in the transcription factor coding THAP1 gene linked to isolated dystonia, numerous investigations have employed transcriptomic studies in DYT-THAP1 models to uncover pathogenic molecular mechanisms underlying dystonia. This review examines key findings from transcriptomic studies conducted on in vivo and in vitro DYT-THAP1 models, which demonstrate that the THAP1-regulated transcriptome is diverse and cell-specific, yet it is bound and co-regulated by a common set of proteins. Prominent among its functions, THAP1 and its co-regulatory network target molecular pathways critical for generating myelinating oligodendrocytes that ensheath axons and generate white matter in the central nervous system. Several lines of investigation have demonstrated the importance of myelination and oligodendrogenesis in motor function during development and in adults, emphasizing the non-cell autonomous contributions of glial cells to neural circuits involved in motor function. Further research on the role of myelin abnormalities in motor deficits in DYT6 models will enhance our understanding of axon-glia interactions in dystonia pathophysiology and provide potential therapeutic interventions targeting these pathways.

A case of novel DYT6 dystonia variant with serious complications after deep brain stimulation therapy: a case report

Background

DYT6 dystonia belongs to a group of isolated, genetically determined, generalized dystonia associated with mutations in the THAP1 gene.

Case presentation

We present the case of a young patient with DYT6 dystonia associated with a newly discovered c14G>A (p.Cys5Tyr) mutation in the THAP1 gene. We describe the clinical phenotype of this new mutation, effect of pallidal deep brain stimulation (DBS), which was accompanied by two rare postimplantation complications: an early intracerebral hemorrhage and delayed epileptic seizures. Among the published case reports of patients with DYT6 dystonia, the mentioned complications have not been described so far.

Conclusions

DBS in the case of DYT6 dystonia is a challenge to thoroughly consider possible therapeutic benefits and potential risks associated with surgery. Genetic heterogeneity of the disease may also play an important role in predicting the development of the clinical phenotype as well as the effect of treatment including DBS. Therefore, it is beneficial to analyze the genetic and clinical relationships of DYT6 dystonia.

Emerging role of a systems biology approach to elucidate factors of reduced penetrance: transcriptional changes in THAP1-linked dystonia as an example

Pathogenic variants in THAP1 can cause dystonia with a penetrance of about 50 %. The underlying mechanisms are unknown and can be considered as means of endogenous disease protection. Since THAP1 encodes a transcription factor, drivers of this variability putatively act at the transcriptome level. Several transcriptome studies tried to elucidate THAP1 function in diverse cellular and mouse models, including mutation carrier-derived cells and iPSC-derived neurons, unveiling various differentially expressed genes and affected pathways. These include nervous system development, dopamine signalling, myelination, or cell-cell adhesion. A network diffusion analysis revealed mRNA splicing, mitochondria, DNA repair, and metabolism as significant pathways that may represent potential targets for therapeutic interventions.

A pathogenic DYT-THAP1 dystonia mutation causes hypomyelination and loss of YY1 binding

Dystonia is a disabling disease that manifests as prolonged involuntary twisting movements. DYT-THAP1 is an inherited form of isolated dystonia caused by mutations in THAP1 encoding the transcription factor THAP1. The phe81leu (F81L) missense mutation is representative of a category of poorly understood mutations that do not occur on residues critical for DNA binding. Here, we demonstrate that the F81L mutation (THAP1F81L) impairs THAP1 transcriptional activity and disrupts CNS myelination. Strikingly, THAP1F81L exhibits normal DNA binding but causes a significantly reduced DNA binding of YY1, its transcriptional partner that also has an established role in oligodendrocyte lineage progression. Our results suggest a model of molecular pathogenesis whereby THAP1F81L normally binds DNA but is unable to efficiently organize an active transcription complex.

Dystonia-specific mutations in THAP1 alter transcription of genes associated with neurodevelopment and myelin

Dystonia is a neurologic disorder associated with an increasingly large number of genetic variants in many genes, resulting in characteristic disturbances in volitional movement. Dissecting the relationships between these mutations and their functional outcomes is critical in understanding the pathways that drive dystonia pathogenesis. Here we established a pipeline for characterizing an allelic series of dystonia-specific mutations. We used this strategy to investigate the molecular consequences of genetic variation in THAP1, which encodes a transcription factor linked to neural differentiation. Multiple pathogenic mutations associated with dystonia cluster within distinct THAP1 functional domains and are predicted to alter DNA-binding properties and/or protein interactions differently, yet the relative impact of these varied changes on molecular signatures and neural deficits is unclear. To determine the effects of these mutations on THAP1 transcriptional activity, we engineered an allelic series of eight alterations in a common induced pluripotent stem cell background and differentiated these lines into a panel of near-isogenic neural stem cells (n = 94 lines). Transcriptome profiling followed by joint analysis of the most robust signatures across mutations identified a convergent pattern of dysregulated genes functionally related to neurodevelopment, lysosomal lipid metabolism, and myelin. On the basis of these observations, we examined mice bearing Thap1-disruptive alleles and detected significant changes in myelin gene expression and reduction of myelin structural integrity relative to control mice. These results suggest that deficits in neurodevelopment and myelination are common consequences of dystonia-associated THAP1 mutations and highlight the potential role of neuron-glial interactions in the pathogenesis of dystonia.

Transposable elements shape the evolution of mammalian development

Transposable elements (TEs) promote genetic innovation but also threaten genome stability. Despite multiple layers of host defence, TEs actively shape mammalian-specific developmental processes, particularly during pre-implantation and extra-embryonic development and at the maternal-fetal interface. Here, we review how TEs influence mammalian genomes both directly by providing the raw material for genetic change and indirectly via co-evolving TE-binding Krüppel-associated box zinc finger proteins (KRAB-ZFPs). Throughout mammalian evolution, individual activities of ancient TEs were co-opted to enable invasive placentation that characterizes live-born mammals. By contrast, the widespread activity of evolutionarily young TEs may reflect an ongoing co-evolution that continues to impact mammalian development.

Isolated dystonia: clinical and genetic updates

Four genes associated with isolated dystonia are currently well replicated and validated. DYT-THAP1 manifests as young-onset generalized dystonia with predominant craniocervical symptoms; and is associated with mostly deleterious missense variation in the THAP1 gene. De novo and inherited missense and protein truncating variation in GNAL as well as primarily missense variation in ANO3 cause isolated focal and/or segmental dystonia with preference for the upper half of the body and older ages at onset. The GAG deletion in TOR1A is associated with generalized dystonia with onset in childhood in the lower limbs. Rare variation in these genes causes monogenic sporadic and inherited forms of isolated dystonia; common variation may confer risk and imply that dystonia is a polygenic trait in a subset of cases. Although candidate gene screens have been successful in the past in detecting gene-disease associations, recent application of whole-genome and whole-exome sequencing methods enable unbiased capture of all genetic variation that may explain the phenotype. However, careful variant-level evaluation is necessary in every case, even in genes that have previously been associated with disease. We review the genetic architecture and phenotype of DYT-THAP1, DYT-GNAL, DYT-ANO3, and DYT-TOR1A by collecting case reports from the literature and performing variant classification using pathogenicity criteria.

Unraveling Molecular Mechanisms of THAP1 Missense Mutations in DYT6 Dystonia

Mutations in THAP1 (THAP domain-containing apoptosis-associated protein 1) are responsible for DYT6 dystonia. Until now, more than eighty different mutations in THAP1 gene have been found in patients with primary dystonia, and two third of them are missense mutations. The potential pathogeneses of these missense mutations in human are largely elusive. In the present study, we generated stable transfected human neuronal cell lines expressing wild-type or mutated THAP1 proteins found in DYT6 patients. Transcriptional profiling using microarrays revealed a set of 28 common genes dysregulated in two mutated THAP1 (S21T and F81L) overexpression cell lines suggesting a common mechanism of these mutations. ChIP-seq showed that THAP1 can bind to the promoter of one of these genes, superoxide dismutase 2 (SOD2). Overexpression of THAP1 in SK-N-AS cells resulted in increased SOD2 protein expression, whereas fibroblasts from THAP1 patients have less SOD2 expression, which indicates that SOD2 is a direct target gene of THAP1. In addition, we show that some THAP1 mutations (C54Y and F81L) decrease the protein stability which might also be responsible for altered transcription regulation due to dosage insufficiency. Taking together, the current study showed different potential pathogenic mechanisms of THAP1 mutations which lead to the same consequence of DYT6 dystonia.

THAP11F80L cobalamin disorder-associated mutation reveals normal and pathogenic THAP11 functions in gene expression and cell proliferation

Twelve human THAP proteins share the THAP domain, an evolutionary conserved zinc-finger DNA-binding domain. Studies of different THAP proteins have indicated roles in gene transcription, cell proliferation and development. We have analyzed this protein family, focusing on THAP7 and THAP11. We show that human THAP proteins possess differing homo- and heterodimer formation properties and interaction abilities with the transcriptional co-regulator HCF-1. HEK-293 cells lacking THAP7 were viable but proliferated more slowly. In contrast, HEK-293 cells were very sensitive to THAP11 alteration. Nevertheless, HEK-293 cells bearing a THAP11 mutation identified in a patient suffering from cobalamin disorder (THAP11F80L) were viable although proliferated more slowly. Cobalamin disorder is an inborn vitamin deficiency characterized by neurodevelopmental abnormalities, most often owing to biallelic mutations in the MMACHC gene, whose gene product MMACHC is a key enzyme in the cobalamin (vitamin B12) metabolic pathway. We show that THAP11F80L selectively affected promoter binding by THAP11, having more deleterious effects on a subset of THAP11 targets, and resulting in altered patterns of gene expression. In particular, THAP11F80L exhibited a strong effect on association with the MMACHC promoter and led to a decrease in MMACHC gene transcription, suggesting that the THAP11F80L mutation is directly responsible for the observed cobalamin disorder.

Loss of the dystonia gene Thap1 leads to transcriptional deficits that converge on common pathogenic pathways in dystonic syndromes

Dystonia is a movement disorder characterized by involuntary and repetitive co-contractions of agonist and antagonist muscles. Dystonia 6 (DYT6) is an autosomal dominant dystonia caused by loss-of-function mutations in the zinc finger transcription factor THAP1. We have generated Thap1 knock-out mice with a view to understanding its transcriptional role. While germ-line deletion of Thap1 is embryonic lethal, mice lacking one Thap1 allele-which in principle should recapitulate the haploinsufficiency of the human syndrome-do not show a discernable phenotype. This is because mice show autoregulation of Thap1 mRNA levels with upregulation at the non-affected locus. We then deleted Thap1 in glial and neuronal precursors using a nestin-conditional approach. Although these mice do not exhibit dystonia, they show pronounced locomotor deficits reflecting derangements in the cerebellar and basal ganglia circuitry. These behavioral features are associated with alterations in the expression of genes involved in nervous system development, synaptic transmission, cytoskeleton, gliosis and dopamine signaling that link DYT6 to other primary and secondary dystonic syndromes.

Dystonia

Dystonia is a neurological condition characterized by abnormal involuntary movements or postures owing to sustained or intermittent muscle contractions. Dystonia can be the manifesting neurological sign of many disorders, either in isolation (isolated dystonia) or with additional signs (combined dystonia). The main focus of this Primer is forms of isolated dystonia of idiopathic or genetic aetiology. These disorders differ in manifestations and severity but can affect all age groups and lead to substantial disability and impaired quality of life. The discovery of genes underlying the mendelian forms of isolated or combined dystonia has led to a better understanding of its pathophysiology. In some of the most common genetic dystonias, such as those caused by TOR1A, THAP1, GCH1 and KMT2B mutations, and idiopathic dystonia, these mechanisms include abnormalities in transcriptional regulation, striatal dopaminergic signalling and synaptic plasticity and a loss of inhibition at neuronal circuits. The diagnosis of dystonia is largely based on clinical signs, and the diagnosis and aetiological definition of this disorder remain a challenge. Effective symptomatic treatments with pharmacological therapy (anticholinergics), intramuscular botulinum toxin injection and deep brain stimulation are available; however, future research will hopefully lead to reliable biomarkers, better treatments and cure of this disorder.

Inherited dystonias: clinical features and molecular pathways

Recent decades have witnessed dramatic increases in understanding of the genetics of dystonia - a movement disorder characterized by involuntary twisting and abnormal posture. Hampered by a lack of overt neuropathology, researchers are investigating isolated monogenic causes to pinpoint common molecular mechanisms in this heterogeneous disease. Evidence from imaging, cellular, and murine work implicates deficiencies in dopamine neurotransmission, transcriptional dysregulation, and selective vulnerability of distinct neuronal populations to disease mutations. Studies of genetic forms of dystonia are also illuminating the developmental dependence of disease symptoms that is typical of many forms of the disease. As understanding of monogenic forms of dystonia grows, a clearer picture will develop of the abnormal motor circuitry behind this relatively common phenomenology. This chapter focuses on the current data covering the etiology and epidemiology, clinical presentation, and pathogenesis of four monogenic forms of isolated dystonia: DYT-TOR1A, DYT-THAP1, DYT-GCH1, and DYT-GNAL.

Screening for THAP1 Mutations in Polish Patients with Dystonia Shows Known and Novel Substitutions

The aim of this study was to assess the presence of DYT6 mutations in Polish patients with isolated dystonia and to characterize their phenotype. We sequenced THAP1 exons 1, 2 and 3 including exon-intron boundaries and 5'UTR fragment in 96 non-DYT1 dystonia patients. In four individuals single nucleotide variations were identified. The coding substitutions were: c. 238A>G (p.Ile80Val), found in two patients, and c.167A>G (p.Glu56Gly), found in one patient. The same variations were present also in the patients' symptomatic as well as asymptomatic relatives. Mutation penetration in the analyzed families was 50-66.7%. In the fourth patient, a novel c.-249C>A substitution in the promoter region was identified. The patient, initially suspected of idiopathic isolated dystonia, finally presented with pantothenate kinase 2-associated neurodegeneration phenotype and was a carrier of two PANK2 mutations. This is the first identified NBIA1 case carrying mutations in both PANK2 and THAP1 genes. In all symptomatic THAP1 mutation carriers (four probands and their three affected relatives) the first signs of dystonia occurred before the age of 23. A primary localization typical for DYT6 dystonia was observed in six individuals. Five subjects developed the first signs of dystonia in the upper limb. In one patient the disease began from laryngeal involvement. An uncommon primary involvement of lower limb was noted in the THAP1 and PANK2 mutations carrier. Neither of these THAP1 substitutions were found in 150 unrelated healthy controls. To the contrary, we identified a heterozygous C/T genotype of c.57C>T single nucleotide variation (p.Pro19Pro, rs146087734) in one healthy control, but in none of the patients. Therefore, a previously proposed association between this substitution and DYT6 dystonia seems unlikely. We found also no significant difference between cases and controls in genotypes distribution of the two-nucleotide -237-236 GA>TT (rs370983900 & rs1844977763) polymorphism.

The involvement of miR-100 in bladder urothelial carcinogenesis changing the expression levels of mRNA and proteins of genes related to cell proliferation, survival, apoptosis and chromosomal stability

Introduction

MicroRNAs (miRNA) are small non-coding RNAs that play an important role in the control of gene expression by inhibiting protein translation or promoting messenger RNA degradation. Today, miRNAs have been shown to be involved in various physiological and pathological cellular processes, including cancer, where they can act as oncogenes or tumor suppressor genes. Recently, lowered expression of miR-100, resulting in upregulation of FGFR3, has been correlated with low-grade, non-invasive bladder urothelial cancer, as an alternative oncogenesis pathway to the typical FGFR3 gene mutation. Our aim is to analyze the role of miR-100 in bladder cancer cell lines in controlling the expression of some of its possible target genes, including FGFR3 and its relationship with proliferation, apoptosis and DNA ploidy.

Methods

The bladder cancer cell lines RT4 and T24 were transfected with pre-miR 100, anti-miR 100 and their respective controls using a lipid-based formulation. After transfection mRNA and protein levels of its supposed target genes THAP2, BAZ2A, mTOR, SMARCA5 and FGFR3 were analyzed by quantitative real time polymerase chain reaction (qRT-PCR) and western blotting. Cell proliferation, apoptosis and DNA ploidy were analyzed by flow cytometry. For statistical analysis, a t-test was applied, p < 0.05 was considered significant.

Results

After miR-100 transfection, there was a significant reduction in the mRNA of mTOR (p = 0.006), SMARCA5 (p = 0.007) and BAZ2A (p = 0.029) in RT4, mTOR (p = 0.023) and SMARCA5 (p = 0.015) in T24. There was a reduction in the expression of all proteins, variable from 22.5% to 57.1% in both cell lines. In T24 miR-100 promoted an increase in cell proliferation and anti-miR 100 promoted apoptosis characterizing miR-100 as an oncomiR in this cell line representative of a high-grade urothelial carcinoma.

Conclusion

miR-100 transfection reduces expression of BAZ2A, mTOR and SMARCA5 mRNA and protein in BC cell lines. miR-100 would be classified as an oncomiR in T24 cells representative of high grade urothelial carcinoma promoting increase in cell proliferation and reduction in apoptosis. The knowledge of miRNA role in tumors will allow their use as tumor markers and targets for new therapies.

MiRNA in bladder carcinogenesis: A review

Bladder cancer (BC) is the second urological malignancy in incidence, currently being one of the most neoplasms studied with profile and biology poorly defined. In the world, BC is responsible by about 386000 new cases and 150000 deaths annually with considerable economic impact and high costs for health systems. After its discovery more than 20 years, micro RNAs (miRNAs) have been recognized as molecules that work specifically in post-transcriptional control in majority of eukaryote genomes. MiRNAs are a family of small non-coding RNAs of 19-25 nucleotides in length, expressed in a wide variety of organisms, comprising plants, worms and mammals, including humans. They have a fundamental role in physiological and pathological processes in organs and tissues in a context-dependent manner. This review brings new roles of protective and oncogenic miRNAs linked to carcinogenesis of urothelial carcinoma of the bladder, and associated with behavior of disease. Many studies have demonstrated promising roles of miRNAs working as diagnostic and prognostic biomarkers or involved in target therapies, consolidating miRNAs as crucial players in human cancer. This review allowed a reflection about the true functions of miRNAs in bladder carcinogenesis. Not only by their wide capacities of action, but also by abilities in define the cell date. The future of anti-tumor target therapies will be based not in one, but in groups of miRNAs working together in several steps of carcinogenic process, being able to identify the disease, predicting behavior and effectively treat bladder cancer.

Inherited isolated dystonia: clinical genetics and gene function

Isolated inherited dystonia-formerly referred to as primary dystonia-is characterized by abnormal motor functioning of a grossly normal appearing brain. The disease manifests as abnormal involuntary twisting movements. The absence of overt neuropathological lesions, while intriguing, has made it particularly difficult to unravel the pathogenesis of isolated inherited dystonia. The explosion of genetic techology enabling the identification of the causative gene mutations is transforming our understanding of dystonia pathogenesis, as the molecular, cellular and circuit level consequences of these mutations are identified in experimental systems. Here, I review the clinical genetics and cell biology of three forms of inherited dystonia for which the causative mutation is known: DYT1 (TOR1A), DYT6 (THAP1), DYT25 (GNAL).

Comparative analysis of evolutionarily conserved motifs of epidermal growth factor receptor 2 (HER2) predicts novel potential therapeutic epitopes

Overexpression of human epidermal growth factor receptor 2 (HER2) is associated with tumor aggressiveness and poor prognosis in breast cancer. With the availability of therapeutic antibodies against HER2, great strides have been made in the clinical management of HER2 overexpressing breast cancer. However, de novo and acquired resistance to these antibodies presents a serious limitation to successful HER2 targeting treatment. The identification of novel epitopes of HER2 that can be used for functional/region-specific blockade could represent a central step in the development of new clinically relevant anti-HER2 antibodies. In the present study, we present a novel computational approach as an auxiliary tool for identification of novel HER2 epitopes. We hypothesized that the structurally and linearly evolutionarily conserved motifs of the extracellular domain of HER2 (ECD HER2) contain potential druggable epitopes/targets. We employed the PROSITE Scan to detect structurally conserved motifs and PRINTS to search for linearly conserved motifs of ECD HER2. We found that the epitopes recognized by trastuzumab and pertuzumab are located in the predicted conserved motifs of ECD HER2, supporting our initial hypothesis. Considering that structurally and linearly conserved motifs can provide functional specific configurations, we propose that by comparing the two types of conserved motifs, additional druggable epitopes/targets in the ECD HER2 protein can be identified, which can be further modified for potential therapeutic application. Thus, this novel computational process for predicting or searching for potential epitopes or key target sites may contribute to epitope-based vaccine and function-selected drug design, especially when x-ray crystal structure protein data is not available.

Emerging common molecular pathways for primary dystonia

The dystonias are a group of hyperkinetic movement disorders whose principal cause is neuron dysfunction at 1 or more interconnected nodes of the motor system. The study of genes and proteins that cause familial dystonia provides critical information about the cellular pathways involved in this dysfunction, which disrupts the motor pathways at the systems level. In recent years study of the increasing number of DYT genes has implicated a number of cell functions that appear to be involved in the pathogenesis of dystonia. A review of the literature published in English-language publications available on PubMed relating to the genetics and cellular pathology of dystonia was performed. Numerous potential pathogenetic mechanisms have been identified. We describe those that fall into 3 emerging thematic groups: cell-cycle and transcriptional regulation in the nucleus, endoplasmic reticulum and nuclear envelope function, and control of synaptic function. © 2013 Movement Disorder Society.

MicroRNA 100: a context dependent miRNA in prostate cancer

OBJECTIVE

MicroRNAs are noncoding RNA molecules involved in the development and progression of tumors. We have found that miRNA-100 is underexpressed in metastatic prostate cancer compared to localized disease. Conversely higher levels of miR-100 are related to biochemical recurrence after surgery. This suggests that miR-100 may be a context-dependent miRNA, acting as oncogene or tumor suppressor miRNA. Our aim is to demonstrate the role of miR-100 in the control of predicted target genes in prostate cancer cell lines.

METHODS

Cell lines DU145 and PC3 were transfected with miR-100, antimiR-100 and after 24 h and 48 h of exposure, qRT-PCR and western blot were performed for mTOR, FGFR3, THAP2, SMARCA5 and BAZ2A.

RESULTS

There was reduction in mTOR (p=0.025), THAP2 (p=0.038), SMARCA5 (p=0.001) and BAZ2A (p=0.006) mRNA expression in DU145 cells after exposure to miR-100. In PC3 cells, mTOR expression was decreased by miR-100 (p=0.01). There was a reduction in the expression levels of proteins encoded by studied genes, ranging from 34% to 69%.

CONCLUSIONS

We demonstrate that miR-100 is a context-dependent miRNA controlling BAZ2, mTOR, FGFR3, SMARCA5 and THAP2 that might be involved in PC progression. The elucidation of the roles of miRNAs in tumors is important because they can be used as therapeutic targets in the future.

Identification of multiple binding sites for the THAP domain of the Galileo transposase in the long terminal inverted-repeats

Galileo is a DNA transposon responsible for the generation of several chromosomal inversions in Drosophila. In contrast to other members of the P-element superfamily, it has unusually long terminal inverted-repeats (TIRs) that resemble those of Foldback elements. To investigate the function of the long TIRs we derived consensus and ancestral sequences for the Galileo transposase in three species of Drosophilids. Following gene synthesis, we expressed and purified their constituent THAP domains and tested their binding activity towards the respective Galileo TIRs. DNase I footprinting located the most proximal DNA binding site about 70 bp from the transposon end. Using this sequence we identified further binding sites in the tandem repeats that are found within the long TIRs. This suggests that the synaptic complex between Galileo ends may be a complicated structure containing higher-order multimers of the transposase. We also attempted to reconstitute Galileo transposition in Drosophila embryos but no events were detected. Thus, although the limited numbers of Galileo copies in each genome were sufficient to provide functional consensus sequences for the THAP domains, they do not specify a fully active transposase. Since the THAP recognition sequence is short, and will occur many times in a large genome, it seems likely that the multiple binding sites within the long, internally repetitive, TIRs of Galileo and other Foldback-like elements may provide the transposase with its binding specificity.

NMR studies of a new family of DNA binding proteins: the THAP proteins

The THAP (THanatos-Associated Protein) domain is an evolutionary conserved C2CH zinc-coordinating domain shared with a large family of cellular factors (THAP proteins). Many members of the THAP family act as transcription factors that control cell proliferation, cell cycle progression, angiogenesis, apoptosis and epigenetic gene silencing. They recognize specific DNA sequences in the promoters of target genes and subsequently recruit effector proteins. Recent structural and functional studies have allowed getting better insight into the nuclear and cellular functions of some THAP members and the molecular mechanisms by which they recognize DNA. The present article reviews recent advances in the knowledge of the THAP domains structures and their interaction with DNA, with a particular focus on NMR. It provides the solution structure of the THAP domain of THAP11, a recently characterized human THAP protein with important functions in transcription and cell growth in colon cancer.

Neural expression of the transcription factor THAP1 during development in rat

Loss of function mutations in THAP1 has been associated with primary generalized and focal dystonia in children and adults. THAP1 encodes a transcription factor (THAP1) that harbors an atypical zinc finger domain and plays a critical role in G(1)-S cell cycle control. Current thinking suggests that dystonia may be a neurodevelopmental circuit disorder. Hence, THAP1 may participate in the development of the nervous system. Herein, we report the neurodevelopmental expression patterns of Thap1 transcript and THAP1 protein from the early postnatal period through adulthood in the rat brain, spinal cord and dorsal root ganglia (DRG). We detected Thap1 transcript and THAP1-immunoreactivity (IR) in the cerebral cortex, cerebellum, striatum, substantia nigra, thalamus, spinal cord and DRG. Thap1 transcript expression was higher in the brain than in spinal cord and DRG at P1 and P7 and declined to similar levels at P14 and later time points in all regions except the cerebellum, where it remained high through adulthood. In the brain, THAP1 expression was highest in early development, particularly in the cerebellum at P7. In addition to Purkinje cells in the cerebellum, THAP1-IR was also localized to pyramidal neurons in the cerebral cortex, relay neurons in the thalamus, medium spiny and cholinergic neurons in the striatum, dopaminergic neurons in the substantia nigra, and pyramidal and interneurons in the hippocampus. In the cerebellar cortex, THAP1-IR was prominently distributed in the perikarya and proximal dendrites of Purkinje cells at early time-points. In contrast, it was more diffusely distributed throughout the dendritic arbor of adult Purkinje cells producing a moderate diffuse staining pattern in the molecular layer. At all time points, nuclear IR was weaker than cytoplasmic IR. The prominent cytoplasmic and developmentally regulated expression of THAP1 suggests that THAP1 may function as part of a cell surface-nucleus signaling cascade involved in terminal neural differentiation.

Mutation screening of the DYT6/THAP1 gene in Serbian patients with primary dystonia

Primary dystonia (PrD) is characterized by sustained muscle contractions, causing twisting and repetitive movements and abnormal postures. Besides DYT1/TOR1A gene, DYT6/THAP1 gene is the second gene known to cause primary pure dystonia. We screened 281 Serbian primary dystonia patients and 106 neurologically healthy control individuals for the GAG deletion in TOR1A gene and for mutations in THAP1 gene by direct sequencing. Nine subjects were found to have the GAG deletion in TOR1A gene. Four coding mutations, including two novel mutations, were identified in the THAP1 gene in five unrelated patients. Two mutations were missense, one was nonsense, and one was 24 bp duplication. None of the coding mutations were seen in 106 control individuals. In addition, one novel nucleotide change in the 5'UTR region of THAP1 gene was detected in two unrelated patients. The mutation frequency of THAP1 gene in Serbian patients with primary dystonia was 1.8 %, similar to the mutation frequency in other populations. Most of the patients reported here with THAP1 mutations had the clinical features of predominantly laryngeal or oromandibular dystonia. Our data expand the genotypic spectrum of THAP1 and strengthen the association with upper body involvement, including the cranial and cervical regions that are usually spared in DYT1-PrD.

Modeling the zing finger protein SmZF1 from Schistosoma mansoni: Insights into DNA binding and gene regulation

Zinc finger proteins are widely found in eukaryotes, representing an important class of DNA-binding proteins frequently involved in transcriptional regulation. Zinc finger motifs are composed by two antiparallel β-strands and one α-helix, stabilized by a zinc ion coordinated by conserved histidine and cysteine residues. In Schistosoma mansoni, these regulatory proteins are known to modulate morphological and physiological changes, having crucial roles in parasite development. A previously described C(2)H(2) zinc finger protein, SmZF1, was shown to be present in cell nuclei of different life stages of S. mansoni and to activate gene transcription in a heterologous system. A high-quality SmZF1 tridimensional structure was generated using comparative modeling. Molecular dynamics simulations of the obtained structure revealed stability of the zinc fingers motifs and high flexibility on the terminals, comparable to the profile observed on the template X-ray structure based on thermal b-factors. Based on the protein tridimensional features and amino acid composition, we were able to characterize four C(2)H(2) zinc finger motifs, the first involved in protein-protein interactions while the three others involved in DNA binding. We defined a consensus DNA binding sequence using three distinct algorithms and further carried out docking calculations, which revealed the interaction of fingers 2-4 with the predicted DNA. A search for S. mansoni genes presenting putative SmZF1 binding sites revealed 415 genes hypothetically under SmZF1 control. Using an automatic annotation and GO assignment approach, we found that the majority of those genes code for proteins involved in developmental processes. Taken together, these results present a consistent base to the structural and functional characterization of SmZF1.

Stage, grade and behavior of bladder urothelial carcinoma defined by the microRNA expression profile

PURPOSE

We identified miRNA expression profiles in urothelial carcinoma that are associated with grade, stage, and recurrence-free and disease specific survival.

MATERIALS AND METHODS

The expression of 14 miRNAs was evaluated by quantitative reverse transcriptase-polymerase chain reaction in surgical specimens from 30 patients with low grade, noninvasive (pTa) and 30 with high grade, invasive (pT2-3) urothelial carcinoma. Controls were normal bladder tissue from 5 patients who underwent surgical treatment for benign prostatic hyperplasia. Endogenous controls were RNU-43 and RNU-48. miRNA profiles were compared and Kaplan-Meier curves were constructed to analyze disease-free and disease specific survival.

RESULTS

miR-100 was under expressed in 100% of low grade pTa specimens (p <0.001) and miR-10a was over expressed in 73.3% (p <0.001). miR-21 and miR-205 were over expressed in high grade pT2-3 disease (p = 0.02 and <0.001, respectively). The other miRNAs were present at levels similar to those of normal bladder tissue or under expressed in each tumor group. miR-21 over expression (greater than 1.08) was related to shorter disease-free survival in patients with low grade pTa urothelial carcinoma. Higher miR-10a levels (greater than 2.30) were associated with shorter disease-free and disease specific survival in patients with high grade pT2-3 urothelial carcinoma.

CONCLUSIONS

Four miRNAs were differentially expressed in the 2 urothelial carcinoma groups. miR-100 and miR-10a showed under expression and over expression, respectively, in low grade pTa tumors. miR-21 and miR-205 were over expressed in pT2-3 disease. In addition, miR-10a and miR-21 over expression was associated with shorter disease-free and disease specific survival. miRNAs could be incorporated into the urothelial carcinoma molecular pathway. These miRNAs could also serve as new diagnostic or prognostic markers and new target drugs.

Towards the classification of DYT6 dystonia mutants in the DNA-binding domain of THAP1

The transcription factor THAP1 (THanatos Associated Protein 1) has emerged recently as the cause of DYT6 primary dystonia, a type of rare, familial and mostly early-onset syndrome that leads to involuntary muscle contractions. Many of the mutations described in the DYT6 patients fall within the sequence-specific DNA-binding domain (THAP domain) of THAP1 and are believed to negatively affect DNA binding. Here, we have used an integrated approach combining spectroscopic (NMR, fluorescence, DSF) and calorimetric (ITC) methods to evaluate the effect of missense mutations, within the THAP domain, on the structure, stability and DNA binding. Our study demonstrates that none of the mutations investigated failed to bind DNA and some of them even bind DNA stronger than the wild-type protein. However, some mutations could alter DNA-binding specificity. Furthermore, the most striking effect is the decrease of stability observed for mutations at positions affecting the zinc coordination, the hydrophobic core or the C-terminal AVPTIF motif, with unfolding temperatures ranging from 46°C for the wild-type to below 37°C for two mutations. These findings suggest that reduction in population of folded protein under physiological conditions could also account for the disease.

A strong 13C chemical shift signature provides the coordination mode of histidines in zinc-binding proteins

Zinc is the second most abundant metal ion incorporated in proteins, and is in many cases a crucial component of protein three-dimensional structures. Zinc ions are frequently coordinated by cysteine and histidine residues. Whereas cysteines bind to zinc via their unique S(γ) atom, histidines can coordinate zinc with two different coordination modes, either N(δ1) or N(ε2) is coordinating the zinc ion. The determination of this coordination mode is crucial for the accurate structure determination of a histidine-containing zinc-binding site by NMR. NMR chemical shifts contain a vast amount of information on local electronic and structural environments and surprisingly their utilization for the determination of the coordination mode of zinc-ligated histidines has been limited so far to (15)N nuclei. In the present report, we observed that the (13)C chemical shifts of aromatic carbons in zinc-ligated histidines represent a reliable signature of their coordination mode. Using a statistical analysis of (13)C chemical shifts, we show that (13)C(δ2) chemical shift is sensitive to the histidine coordination mode and that the chemical shift difference δ{(13)C(ε1)} - δ{(13)C(δ2)} provides a reference-independent marker of this coordination mode. The present approach allows the direct determination of the coordination mode of zinc-ligated histidines even with non-isotopically enriched protein samples and without any prior structural information.

Genotype-phenotype correlations in THAP1 dystonia: molecular foundations and description of new cases

An extensive variety of THAP1 sequence variants have been associated with focal, segmental and generalized dystonia with age of onset ranging from 3 to over 60 years. In previous work, we screened 1114 subjects with mainly adult-onset primary dystonia (Neurology 2010; 74:229-238) and identified 6 missense mutations in THAP1. For this report, we screened 750 additional subjects for mutations in coding regions of THAP1 and interrogated all published descriptions of THAP1 phenotypes (gender, age of onset, anatomical distribution of dystonia, family history and site of onset) to explore the possibility of THAP1 genotype-phenotype correlations and facilitate a deeper understanding of THAP1 pathobiology. We identified 5 additional missense mutations in THAP1 (p.A7D, p.K16E, p.S21C, p.R29Q, and p.I80V). Three of these variants are associated with appendicular tremors, which were an isolated or presenting sign in some of the affected subjects. Abductor laryngeal dystonia and mild blepharospasm can be manifestations of THAP1 mutations in some individuals. Overall, mean age of onset for THAP1 dystonia is 16.8 years and the most common sites of onset are the arm and neck, and the most frequently affected anatomical site is the neck. In addition, over half of patients exhibit either cranial or laryngeal involvement. Protein truncating mutations and missense mutations within the THAP domain of THAP1 tend to manifest at an earlier age and exhibit more extensive anatomical distributions than mutations localized to other regions of THAP1.

A transcriptional regulatory role of the THAP11-HCF-1 complex in colon cancer cell function

The recently identified Thanatos-associated protein (THAP) domain is an atypical zinc finger motif with sequence-specific DNA-binding activity. Emerging data suggest that THAP proteins may function in chromatin-dependent processes, including transcriptional regulation, but the roles of most THAP proteins in normal and aberrant cellular processes remain largely unknown. In this work, we identify THAP11 as a transcriptional regulator differentially expressed in human colon cancer. Immunohistochemical analysis of human colon cancers revealed increased THAP11 expression in both primary tumors and metastases. Knockdown of THAP11 in SW620 colon cancer cells resulted in a significant decrease in cell proliferation, and profiling of gene expression in these cells identified a novel gene set composed of 80 differentially expressed genes, 70% of which were derepressed by THAP11 knockdown. THAP11 was found to associate physically with the transcriptional coregulator HCF-1 (host cell factor 1) and recruit HCF-1 to target promoters. Importantly, THAP11-mediated gene regulation and its chromatin association require HCF-1, while HCF-1 recruitment at these genes requires THAP11. Collectively, these data provide the first characterization of THAP11-dependent gene expression in human colon cancer cells and suggest that the THAP11-HCF-1 complex may be an important transcriptional and cell growth regulator in human colon cancer.

The multi-zinc finger protein ZNF217 contacts DNA through a two-finger domain

Classical C2H2 zinc finger proteins are among the most abundant transcription factors found in eukaryotes, and the mechanisms through which they recognize their target genes have been extensively investigated. In general, a tandem array of three fingers separated by characteristic TGERP links is required for sequence-specific DNA recognition. Nevertheless, a significant number of zinc finger proteins do not contain a hallmark three-finger array of this type, raising the question of whether and how they contact DNA. We have examined the multi-finger protein ZNF217, which contains eight classical zinc fingers. ZNF217 is implicated as an oncogene and in repressing the E-cadherin gene. We show that two of its zinc fingers, 6 and 7, can mediate contacts with DNA. We examine its putative recognition site in the E-cadherin promoter and demonstrate that this is a suboptimal site. NMR analysis and mutagenesis is used to define the DNA binding surface of ZNF217, and we examine the specificity of the DNA binding activity using fluorescence anisotropy titrations. Finally, sequence analysis reveals that a variety of multi-finger proteins also contain two-finger units, and our data support the idea that these may constitute a distinct subclass of DNA recognition motif.

Novel THAP1 gene mutations in patients with primary dystonia from southwest China

BACKGROUND

Clinical presentation and DYT6/THAP1 mutations among Chinese patients with primary dystonia have not been well studied.

METHODS

Patients with primary pure dystonia from Southwest China who did not have a mutation in DYT1 exon 5 were included in the present study. Mutations of the THAP1 gene were screened by direct sequencing.

RESULTS

A total of 231 patients were examined. Cervical dystonia (58.47%) was found to be the most frequent form of focal dystonia. Novel heterozygous missense mutation [c.521A>G (p.E174G)] was found in exon 3 of the THAP1 gene in one patient and one insertion mutation [c.214_215InsA (p.L72fsX86)] in exon 2 in another. Initial symptoms of patients with these mutations were early-onset cervical dystonia. Both patients had no dysarthria. A silent change [c.489C>G (p.L63L)] in exon 3 was identified in three patients with Meige syndrome.

CONCLUSION

The mutation frequency of the THAP1 gene was 0.87% in Chinese patients with primary pure dystonia, similar to the mutation frequency found in other ethnic groups. Patients presenting with early-onset cervical dystonia should be screened for THAP1 gene mutations to fully assess all the possible etiologies of dystonia. Further studies are needed for p.L63L in THAP1 in Meige syndrome.

Dimerization of the DYT6 dystonia protein, THAP1, requires residues within the coiled-coil domain

Thanatos-associated [THAP] domain-containing apoptosis-associated protein 1 (THAP1) is a DNA-binding protein that has been recently associated with DYT6 dystonia, a hereditary movement disorder involving sustained, involuntary muscle contractions. A large number of dystonia-related mutations have been identified in THAP1 in diverse patient populations worldwide. Previous reports have suggested that THAP1 oligomerizes with itself via a C-terminal coiled-coil domain, raising the possibility that DYT6 mutations in this region might affect this interaction. In this study, we examined the ability of wild-type THAP1 to bind itself and the effects on this interaction of the following disease mutations: C54Y, F81L, ΔF132, T142A, I149T, Q154fs180X, and A166T. The results confirmed that wild-type THAP1 associated with itself and most of the DYT6 mutants tested, except for the Q154fs180X variant, which loses most of the coiled-coil domain because of a frameshift at position 154. However, deletion of C-terminal residues after position 166 produced a truncated variant of THAP1 that was able to bind the wild-type protein. The interaction of THAP1 with itself therefore required residues within a 13-amino acid region (aa 154-166) of the coiled-coil domain. Further inspection of this sequence revealed elements highly consistent with previous descriptions of leucine zippers, which serve as dimerization domains in other transcription factor families. Based on this similarity, a structural model was generated to predict how hydrophobic residues in this region may mediate dimerization. These observations offer additional insight into the role of the coiled-coil domain in THAP1, which may facilitate future analyses of DYT6 mutations in this region.

Phylogenetic and functional characterization of the hAT transposon superfamily

Transposons are found in virtually all organisms and play fundamental roles in genome evolution. They can also acquire new functions in the host organism and some have been developed as incisive genetic tools for transformation and mutagenesis. The hAT transposon superfamily contains members from the plant and animal kingdoms, some of which are active when introduced into new host organisms. We have identified two new active hAT transposons, AeBuster1, from the mosquito Aedes aegypti and TcBuster from the red flour beetle Tribolium castaneum. Activity of both transposons is illustrated by excision and transposition assays performed in Drosophila melanogaster and Ae. aegypti and by in vitro strand transfer assays. These two active insect transposons are more closely related to the Buster sequences identified in humans than they are to the previously identified active hAT transposons, Ac, Tam3, Tol2, hobo, and Hermes. We therefore reexamined the structural and functional relationships of hAT and hAT-like transposase sequences extracted from genome databases and found that the hAT superfamily is divided into at least two families. This division is supported by a difference in target-site selections generated by active transposons of each family. We name these families the Ac and Buster families after the first identified transposon or transposon-like sequence in each. We find that the recently discovered SPIN transposons of mammals are located within the family of Buster elements.

The c.-237_236GA>TT THAP1 sequence variant does not increase risk for primary dystonia

BACKGROUND

Sequence variants in coding and noncoding regions of THAP1 have been associated with primary dystonia.

METHODS

In this study, 1,446 Caucasian subjects with mainly adult-onset primary dystonia and 1,520 controls were genotyped for a variant located in the 5'-untranslated region of THAP1 (c.-237_236GA>TT).

RESULTS

Minor allele frequencies were 62/2892 (2.14%) and 55/3040 (1.81%) in subjects with dystonia and controls, respectively (P=0.202). Subgroup analyses by gender and anatomical distribution also failed to attain statistical significance. In addition, there was no effect of the TT variant on expression levels of THAP1 transcript or protein.

DISCUSSION

Our findings indicate that the c.-237_236GA>TT THAP1 sequence variant does not increase risk for adult-onset primary dystonia in Caucasians.

A green fluorescent protein solubility screen in E. coli reveals domain boundaries of the GTP-binding domain in the P element transposase

Guanosine triphosphate (GTP) binding and hydrolysis events often act as molecular switches in proteins, modulating conformational changes between active and inactive states in many signaling molecules and transport systems. The P element transposase of Drosophila melanogaster requires GTP binding to proceed along its reaction pathway, following initial site-specific DNA binding. GTP binding is unique to P elements and may represent a novel form of transpositional regulation, allowing the bound transposase to find a second site, looping the transposon DNA for strand cleavage and excision. The GTP-binding activity has been previously mapped to the central portion of the transposase protein; however, the P element transposase contains little sequence identity with known GTP-binding folds. To identify soluble, active transposase domains, a GFP solubility screen was used testing the solubility of random P element gene fragments in E. coli. The screen produced a single clone spanning known GTP-binding residues in the central portion of the transposase coding region. This clone, amino acids 275-409 in the P element transposase, was soluble, highly expressed in E.coli and active for GTP-binding activity, therefore is a candidate for future biochemical and structural studies. In addition, the chimeric screen revealed a minimal N-terminal THAP DNA-binding domain attached to an extended leucine zipper coiled-coil dimerization domain in the P element transposase, precisely delineating the DNA-binding and dimerization activities on the primary sequence. This study highlights the use of a GFP-based solubility screen on a large multidomain protein to identify highly expressed, soluble truncated domain subregions.

Spasmodic dysphonia: a laryngeal control disorder specific to speech

Spasmodic dysphonia (SD) is a rare neurological disorder that emerges in middle age, is usually sporadic, and affects intrinsic laryngeal muscle control only during speech. Spasmodic bursts in particular laryngeal muscles disrupt voluntary control during vowel sounds in adductor SD and interfere with voice onset after voiceless consonants in abductor SD. Little is known about its origins; it is classified as a focal dystonia secondary to an unknown neurobiological mechanism that produces a chronic abnormality of laryngeal motor neuron regulation during speech. It develops primarily in females and does not interfere with breathing, crying, laughter, and shouting. Recent postmortem studies have implicated the accumulation of clusters in the parenchyma and perivascular regions with inflammatory changes in the brainstem in one to two cases. A few cases with single mutations in THAP1, a gene involved in transcription regulation, suggest that a weak genetic predisposition may contribute to mechanisms causing a nonprogressive abnormality in laryngeal motor neuron control for speech but not for vocal emotional expression. Research is needed to address the basic cellular and proteomic mechanisms that produce this disorder to provide intervention that could target the pathogenesis of the disorder rather than only providing temporary symptom relief.

Molecular pathways in dystonia

The hereditary dystonias comprise a set of diseases defined by a common constellation of motor deficits. These disorders are most likely associated with different molecular etiologies, many of which have yet to be elucidated. Here we discuss recent advances in three forms of hereditary dystonia, DYT1, DYT6 and DYT16, which share a similar clinical picture: onset in childhood or adolescence, progressive spread of symptoms with generalized involvement of body regions and a steady state affliction without treatment. Unlike DYT1, the genes responsible for DYT6 and DYT16 have only recently been identified, with relatively little information about the function of the encoded proteins. Nevertheless, recent data suggest that these proteins may fit together within interacting pathways involved in dopaminergic signaling, transcriptional regulation, and cellular stress responses. This review focuses on these molecular pathways, highlighting potential common themes among these dystonias which may serve as areas for future research. This article is part of a Special Issue entitled "Advances in dystonia".

THAP5 is a DNA-binding transcriptional repressor that is regulated in melanoma cells during DNA damage-induced cell death

THAP5 was originally isolated as a specific interactor and substrate of the mitochondrial pro-apoptotic Omi/HtrA2 protease. It is a human zinc finger protein characterized by a restricted pattern of expression and the lack of orthologs in mouse and rat. The biological function of THAP5 is unknown but our previous studies suggest it could regulate G2/M transition in kidney cells and could be involved in human cardiomyocyte cell death associated with coronary artery disease (CAD). In this report, we expanded our studies on the properties and function of THAP5 in human melanoma cells. THAP5 was expressed in primary human melanocytes as well as in all melanoma cell lines that were tested. THAP5 protein level was significantly induced by UV irradiation or cisplatin treatment, conditions known to cause DNA damage. The induction of THAP5 correlated with a significant increase in apoptotic cell death. In addition, we show that THAP5 is a nuclear protein that could recognize and bind a specific DNA motif. THAP5 could also repress the transcription of a reporter gene in a heterologous system. Our work suggests that THAP5 is a DNA-binding protein and a transcriptional repressor. Furthermore, THAP5 has a pro-apoptotic function and it was induced in melanoma cells under conditions that promoted cell death.

Direct interaction between causative genes of DYT1 and DYT6 primary dystonia

Primary dystonia is a movement disorder characterized by sustained muscle contractions and in which dystonia is the only or predominant clinical feature. TOR1A(DYT1) and the transcription factor THAP1(DYT6) are the only genes identified thus far for primary dystonia. Using electromobility shift assays and chromatin immunoprecipitation (ChIP) quantitative polymerase chain reaction (qPCR), we demonstrate a physical interaction between THAP1 and the TOR1A promoter that is abolished by pathophysiologic mutations. Our findings provide the first evidence that causative genes for primary dystonia intersect in a common pathway and raise the possibility of developing novel therapies targeting this pathway.

Clinical and genetic evaluation of DYT1 and DYT6 primary dystonia in China

BACKGROUND

Dystonia is defined as the presence of sustained involuntary muscle contractions, often leading to abnormal posture and movement. DYT1 is caused by a mutation in the TOR1A gene, whilst mutations in THAP1 gene have been identified as responsible for DYT6. The relative frequency and phenotype differences between DYT1 and DYT6 amongst Chinese primary dystonia patients have not been well-characterized.

PATIENTS AND METHODS

One hundred eleven unrelated Chinese patients with primary dystonia were screened for mutations in TOR1A and THAP1 genes, and correlate this with clinical presentation. Exon 5 of TOR1A and all three exons and exon-intron conjunctions in THAP1 were screened by direct sequencing.

RESULTS

Three subjects were found to have the GAG deletion in the TOR1A gene, and two patients were detected with THAP1 gene mutations/variations (c.224A>T, c.449A>C). The overall mutation frequency was 4.5% in this cohort with TOR1A mutations found in 2.7% and THAP1 mutations found in 1.8%. No mutations were detected in the controls composed of 100 normal Chinese subjects. The clinical presentations of the DYT1 cases included onset in the limbs that could progress to the generalized dystonia within several years but without cranial involvement. Whilst in the DYT6 cases, the onset was cranial or cervical and progresses very slowly.

CONCLUSION

The major clinical differences between DYT1 and DYT6 dystonia in China were the cranial involvement in DYT6 and progress to general dystonia within several years in DYT1.