Characterization of tweety gene (ttyh1-3) expression in Xenopus laevis during embryonic development

Tumor microtubes: A new potential therapeutic target for high-grade gliomas

High-grade infiltrating gliomas are highly aggressive and fatal brain tumors that present significant challenges for research and treatment due to their complex microenvironment and tissue structure. Recent discovery of tumor microtubes (TMs) has provided new insights into how high-grade gliomas develop in the brain and resist treatment. TMs are unique, ultra-long, and highly functional membrane protrusions that form multicellular networks and play crucial roles in glioma invasiveness, drug resistance, recurrence, and heterogeneity. This review focuses on the different roles that TMs play in glioma cell communication, material transport, and tumor cell behavior. Specifically, non-connecting TMs primarily promote glioma invasiveness, likely related to their role in enhancing cell motility. On the other hand, interconnecting TMs form functional and communication networks by connecting with surrounding astrocytes and neurons, thereby promoting glioma malignancy. We summarize the factors that influence the formation of TMs in gliomas and current strategies targeting TMs. As the understanding of TMs advances, we are closer to uncovering whether they might be the long-sought Achilles' heel of treatment-resistant gliomas. By delving deeper into TMs research, we hope to develop more effective therapeutic strategies for patients with malignant gliomas.

Prominin 1 and Tweety Homology 1 both induce extracellular vesicle formation

Prominin 1 (Prom1) is a five-transmembrane pass integral membrane protein that associates with curved regions of the plasma membrane. Prom1 interacts with membrane cholesterol and actively remodels the plasma membrane. Membrane-bending activity is particularly evident in photoreceptors, where Prom1 loss-of-function mutations cause failure of outer segment homeostasis, leading to cone-rod retinal dystrophy (CRRD). The Tweety Homology (Ttyh) protein family has been proposed to be homologous to Prominin, but it is not known whether Ttyh proteins have an analogous membrane-bending function. Here, we characterize the membrane-bending activity of human Prom1 and Ttyh1 in native bilayer membranes. We find that Prom1 and Ttyh1 both induce formation of extracellular vesicles (EVs) in cultured mammalian cells and that the EVs produced are physically similar. Ttyh1 is more abundant in EV membranes than Prom1 and produces EVs with membranes that are more tubulated than Prom1 EVs. We further show that Prom1 interacts more stably with membrane cholesterol than Ttyh1 and that this may contribute to membrane-bending inhibition in Prom1 EVs. Intriguingly, a loss-of-function mutation in Prom1 associated with CRRD induces particularly stable cholesterol binding. These experiments provide mechanistic insight into Prominin function in CRRD and suggest that Prom and Ttyh belong to a single family of functionally related membrane-bending, EV-generating proteins.

Tweety homolog 3 promotes colorectal cancer progression through mutual regulation of histone deacetylase 7

Colorectal cancer (CRC) is one of the leading cancers worldwide, with metastasis being a major cause of high mortality rates among patients. In this study, dysregulated gene Tweety homolog 3 (TTYH3) was identified by Gene Expression Omnibus database. Public databases were used to predict potential competing endogenous RNAs (ceRNAs) for TTYH3. Quantitative real-time polymerase chain reaction, western blot, and immunohistochemistry were utilized to analyze TTYH3 and histone deacetylase 7 (HDAC7) levels. Luciferase assays confirmed miR-1271-5p directly targeting the 3' untranslated regions of TTYH3 and HDAC7. In vitro experiments such as transwell and human umbilical vein endothelial cell tube formation, as well as in vivo mouse models, were conducted to assess the biological functions of TTYH3 and HDAC7. We discovered that upregulation of TTYH3 in CRC promotes cell migration by affecting the Epithelial-mesenchymal transition pathway, which was independent of its ion channel activity. Mechanistically, TTYH3 and HDAC7 functioned as ceRNAs, reciprocally regulating each other's expression. TTYH3 competes for binding miR-1271-5p, increasing HDAC7 expression, facilitating CRC metastasis and angiogenesis. This study reveals the critical role of TTYH3 in promoting CRC metastasis through ceRNA crosstalk, offering new insights into potential therapeutic targets for clinical intervention.

Prominin 1 and Tweety Homology 1 both induce extracellular vesicle formation

Prominin-1 (Prom1) is a five-transmembrane-pass integral membrane protein that associates with curved regions of the plasma membrane. Prom1 interacts with membrane cholesterol and actively remodels the plasma membrane. Membrane bending activity is particularly evident in photoreceptors, where Prom1 loss-of-function mutations cause failure of outer segment homeostasis, leading to cone-rod retinal dystrophy (CRRD). The Tweety Homology (Ttyh) protein family has been proposed to be homologous to Prominin, but it is not known whether Ttyh proteins have an analogous membrane-bending function. Here, we characterize the membrane-bending activity of human Prom1 and Ttyh1 in native bilayer membranes. We find that Prom1 and Ttyh1 both induce formation of extracellular vesicles (EVs) in cultured mammalian cells and that the EVs produced are physically similar. Ttyh1 is more abundant in EV membranes than Prom1 and produces EVs with membranes that are more tubulated than Prom1 EVs. We further show that Prom1 interacts more stably with membrane cholesterol than Ttyh1 and that this may contribute to membrane bending inhibition in Prom1 EVs. Intriguingly, a loss-of-function mutation in Prom1 associated with CRRD induces particularly stable cholesterol binding. These experiments provide mechanistic insight into Prominin function in CRRD and suggest that Prom and Ttyh belong to a single family of functionally related membrane-bending, EV-generating proteins.

Drosophila tweety facilitates autophagy to regulate mitochondrial homeostasis and bioenergetics in Glia

Mitochondria support the energetic demands of the cells. Autophagic turnover of mitochondria serves as a critical pathway for mitochondrial homeostasis. It is unclear how bioenergetics and autophagy are functionally connected. Here, we identify an endolysosomal membrane protein that facilitates autophagy to regulate ATP production in glia. We determined that Drosophila tweety (tty) is highly expressed in glia and localized to endolysosomes. Diminished fusion between autophagosomes and endolysosomes in tty-deficient glia was rescued by expressing the human Tweety Homolog 1 (TTYH1). Loss of tty in glia attenuated mitochondrial turnover, elevated mitochondrial oxidative stress, and impaired locomotor functions. The cellular and organismal defects were partially reversed by antioxidant treatment. We performed live-cell imaging of genetically encoded metabolite sensors to determine the impact of tty and autophagy deficiencies on glial bioenergetics. We found that tty-deficient glia exhibited reduced mitochondrial pyruvate consumption accompanied by a shift toward glycolysis for ATP production. Likewise, genetic inhibition of autophagy in glia resulted in a similar glycolytic shift in bioenergetics. Furthermore, the survival of mutant flies became more sensitive to starvation, underlining the significance of tty in the crosstalk between autophagy and bioenergetics. Together, our findings uncover the role for tty in mitochondrial homeostasis via facilitating autophagy, which determines bioenergetic balance in glia.

The TTYH3/MK5 Positive Feedback Loop regulates Tumor Progression via GSK3-β/β-catenin signaling in HCC

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide, and identification of novel targets is necessary for its diagnosis and treatment. This study aimed to investigate the biological function and clinical significance of tweety homolog 3 (TTYH3) in HCC. TTYH3 overexpression promoted cell proliferation, migration, and invasion and inhibited HCCM3 and Hep3B cell apoptosis. TTYH3 promoted tumor formation and metastasis in vivo. TTYH3 upregulated calcium influx and intracellular chloride concentration, thereby promoting cellular migration and regulating epithelial-mesenchymal transition-related protein expression. The interaction between TTYH3 and MK5 was identified through co-immunoprecipitation assays and protein docking. TTYH3 promoted the expression of MK5, which then activated the GSK3β/β-catenin signaling pathway. MK5 knockdown attenuated the activation of GSK3β/β-catenin signaling by TTYH3. TTYH3 expression was regulated in a positive feedback manner. In clinical HCC samples, TTYH3 was upregulated in the HCC tissues compared to nontumor tissues. Furthermore, high TTYH3 expression was significantly correlated with poor patient survival. The CpG islands were hypomethylated in the promoter region of TTYH3 in HCC tissues. In conclusion, we identified TTYH3 regulates tumor development and progression via MK5/GSK3-β/β-catenin signaling in HCC and promotes itself expression in a positive feedback loop.

Potential involvement of the microbiota-gut-brain axis in the neurotoxicity of triphenyl phosphate (TPhP) in the marine medaka (Oryzias melastigma) larvae

Triphenyl phosphate (TPhP), a prevalent pollutant in the aquatic environment, has been reported to induce neurotoxicity (e.g., a suppression in locomotor activity) in fish larvae, posing a great threat to fish populations. However, the underlying mechanism was not fully revealed. In this study, the Oryzias melastigma larvae (21 dph) were exposed to waterborne TPhP (20 and 100 μg/L) for 7 days and a decreased locomotor activity was found. After exposure, the brain transcriptome and communities of gut microbiota were investigated to explore the potential mechanism underlying the suppressed locomotor activity by TPhP. The results showed that 1160 genes in the brain were dysregulated by TPhP, of which 24 genes were identified as being highly associated with the neural function and development (including nerve regeneration, neuronal growth and differentiation, brain ion homeostasis, production of neurotransmitters and etc), suggesting a general impairment in the central nervous system. Meanwhile, TPhP caused disorders in the gut microbiota. The relative abundance of Gammaproteobacteria and Alphaproteobacteria, which can influence the brain functions of host via the microbiota-gut-brain axis, were significantly altered by TPhP. Furthermore, the Redundancy analysis (RDA) revealed positive correlations between the intestinal genera Ruegeria, Roseivivax and Nautella and the dysregulated brain genes by TPhP. These results suggest that TPhP might impair the central nervous system of the O. melastigma larvae not only directly but also through the microbiota-gut-axis (indirectly), contributing to the suppressed locomotor activity. These findings enrich our mechanistic understanding of the toxicity of TPhP in fish larvae and shed preliminary light on the involvement of microbiota-gut-brain axis in the neurotoxicity of environmental pollutants.

Structures of tweety homolog proteins TTYH2 and TTYH3 reveal a Ca2+-dependent switch from intra- to intermembrane dimerization

Tweety homologs (TTYHs) comprise a conserved family of transmembrane proteins found in eukaryotes with three members (TTYH1-3) in vertebrates. They are widely expressed in mammals including at high levels in the nervous system and have been implicated in cancers and other diseases including epilepsy, chronic pain, and viral infections. TTYHs have been reported to form Ca²⁺- and cell volume-regulated anion channels structurally distinct from any characterized protein family with potential roles in cell adhesion, migration, and developmental signaling. To provide insight into TTYH family structure and function, we determined cryo-EM structures of Mus musculus TTYH2 and TTYH3 in lipid nanodiscs. TTYH2 and TTYH3 adopt a previously unobserved fold which includes an extended extracellular domain with a partially solvent exposed pocket that may be an interaction site for hydrophobic molecules. In the presence of Ca²⁺, TTYH2 and TTYH3 form homomeric cis-dimers bridged by extracellularly coordinated Ca²⁺. Strikingly, in the absence of Ca²⁺, TTYH2 forms trans-dimers that span opposing membranes across a ~130 Å intermembrane space as well as a monomeric state. All TTYH structures lack ion conducting pathways and we do not observe TTYH2-dependent channel activity in cells. We conclude TTYHs are not pore forming subunits of anion channels and their function may involve Ca²⁺-dependent changes in quaternary structure, interactions with hydrophobic molecules near the extracellular membrane surface, and/or association with additional protein partners.

Upregulation of TTYH3 promotes epithelial-to-mesenchymal transition through Wnt/β-catenin signaling and inhibits apoptosis in cholangiocarcinoma

PURPOSE

Cholangiocarcinoma (CCA) is a highly invasive malignant tumor originating from the bile duct epithelium. Tweety homolog 3 (TTYH3) is a member of the family of calcium-activated chloride channels, which have several biological functions. Here, we aimed to investigate the expression and biological function of TTYH3 in CCA.

METHODS

The mRNA and protein expression levels of TTYH3 were investigated in primary human CCA tissues and normal tissues. The DNA methylation levels of three CpG sites in the TTYH3 promoter region were evaluated using pyrosequencing. The effect of TTYH3 expression on proliferation, apoptosis, migration and invasion were assessed in HUCCT1 and QBC939 cells. Xenograft models were developed to substantiate its role in the development of CCA. Western blot analysis was used to investigate the mechanistic role of TTYH3 in regulating CCA progression.

RESULTS

We found that TTYH3 was highly expressed both at the mRNA and protein levels in CCA (p = 0.0001) and that the expression levels were significantly related to a poor overall survival of the patients (p = 0.0019). The DNA methylation levels of three CpG sites in the TTYH3 promoter region were significantly lower in CCA tissues compared to normal tissues (p < 0.05). In vitro studies indicated that TTYH3 can promote the proliferation, migration and invasion of the CCA cells. TTYH3 overexpression significantly promoted tumor progression and cellular proliferation in vivo as indicated by Ki-67 expression. In addition, we found that exogenous TTYH3 overexpression induced epithelial-mesenchymal transition (EMT) in CCA as indicated by expression changes in E-cadherin, N-cadherin and vimentin. The EMT process was found to occur through the Wnt/β-catenin signaling pathway, with simultaneous changes in P-GSK3β and β-catenin levels.

CONCLUSIONS

Our data indicate that DNA hypomethylation-induced overexpression of TTYH3 regulates CCA development and metastasis through the Wnt/β-catenin pathway.

Transmembrane Protein Ttyh1 Maintains the Quiescence of Neural Stem Cells Through Ca2+/NFATc3 Signaling

The quiescence, activation, and subsequent neurogenesis of neural stem cells (NSCs) play essential roles in the physiological homeostasis and pathological repair of the central nervous system. Previous studies indicate that transmembrane protein Ttyh1 is required for the stemness of NSCs, whereas the exact functions in vivo and precise mechanisms are still waiting to be elucidated. By constructing Ttyh1-promoter driven reporter mice, we determined the specific expression of Ttyh1 in quiescent NSCs and niche astrocytes. Further evaluations on Ttyh1 knockout mice revealed that Ttyh1 ablation leads to activated neurogenesis and enhanced spatial learning and memory in adult mice (6-8 weeks). Correspondingly, Ttyh1 deficiency results in accelerated exhaustion of NSC pool and impaired neurogenesis in aged mice (12 months). By RNA-sequencing, bioinformatics and molecular biological analysis, we found that Ttyh1 is involved in the regulation of calcium signaling in NSCs, and transcription factor NFATc3 is a critical effector in quiescence versus cell cycle entry regulated by Ttyh1. Our research uncovered new endogenous mechanisms that regulate quiescence versus activation of NSCs, therefore provide novel targets for the intervention to activate quiescent NSCs to participate in injury repair during pathology and aging.

Elevated expression of Tweety homologue 3 predicts poor clinical outcomes in ovarian cancer

Objective: To define the alteration of tweety homolog (TTYH) expression in patients with ovarian carcinoma (OC) and its correlation to prognosis.

Methods: Kaplan-Meier (KM) plotter was used to evaluate the association between TTYHs expression and clinical outcomes of OC patients. The distribution of 20-year overall survival (OS) and progression-free survival (PFS) was estimated using KM survival plots. The mRNA expression of TTYHs in OC and normal ovarian tissues was confirmed by the Oncomine database. Then, using immunohistochemistry assay, the expression of TTYH1 and TTYH3 proteins in serous OC and normal ovarian tissues was detected. In addition, the protein and mRNA levels of TTYH1 and TTYH3 in human OC cell lines ES-2, A2780 and SKOV3 and normal ovarian epithelial cell lines IOSE80 were assessed by western blotting and real-time quantitative polymerase chain reaction (qRT-PCR).

Results: TTYH1 possessed meaningful significance in predicting better prognosis in the serous, advanced stage, and well-differentiated OC patients, while TTYH3 expression predicted worse prognosis in serous, late-stage, and poorly differentiated OC patients. High expression of TTYH1 displayed an association with favorable PFS in OC patients with TP53 mutation. However, enhanced TTYH3 was related to an adverse clinical outcome in TP53-mutated OC patients. In addition, TTYH1 was related to a better clinical outcome in OC patients with platinums-based chemotherapy, but only indicated improved overall survival in OC patients who received taxol or platin + taxol chemotherapy. The up-regulated expression of TTYH3 predicted worse survival in OC patients receiving platin, taxol, or platin + taxol chemotherapy regimen. The levels of TTYH3 mRNA and protein were higher in OC cells and tissues when compared to normal ovarian cells and tissues.

Conclusions: TTYH3 was a potential predictor for poor clinical outcome in OC patients, particularly in patients with serous, late-stage, poorly differentiated, TP53-mutation or the patients treated with chemotherapy regimens (platin, taxol, or platin + taxol).

The tweety Gene Family: From Embryo to Disease

The tweety genes encode gated chloride channels that are found in animals, plants, and even simple eukaryotes, signifying their deep evolutionary origin. In vertebrates, the tweety gene family is highly conserved and consists of three members—ttyh1, ttyh2, and ttyh3—that are important for the regulation of cell volume. While research has elucidated potential physiological functions of ttyh1 in neural stem cell maintenance, proliferation, and filopodia formation during neural development, the roles of ttyh2 and ttyh3 are less characterized, though their expression patterns during embryonic and fetal development suggest potential roles in the development of a wide range of tissues including a role in the immune system in response to pathogen-associated molecules. Additionally, members of the tweety gene family have been implicated in various pathologies including cancers, particularly pediatric brain tumors, and neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. Here, we review the current state of research using information from published articles and open-source databases on the tweety gene family with regard to its structure, evolution, expression during development and adulthood, biochemical and cellular functions, and role in human disease. We also identify promising areas for further research to advance our understanding of this important, yet still understudied, family of genes.

Discovery of key genes as novel biomarkers specifically associated with HPV-negative cervical cancer

Cervical cancer is a common female malignancy that is mainly caused by human papillomavirus (HPV) infection. However, the incidence of HPV-negative cervical cancer has shown an increasing trend in recent years. Because the mechanism of HPV-negative cervical cancer development is unclear, this study aims to find the pattern of differential gene expression in HPV-negative cervical cancer and verify the underlying potential mechanism. Differentially expressed genes were compared among HPV-positive cervical cancer, HPV-negative cervical cancer, and normal cervical tissues retrieved from TCGA. Subsequently, dysregulated differentially expressed genes specifically existed in HPV-negative cervical cancer tissues and HPV-negative cell lines were validated by qRT-PCR, western blotting, and immunohistochemical staining. We found seventeen highly expressed genes that were particularly associated with HPV-negative cervical cancer from analysis of TCGA database. Among the 17 novel genes, 7 genes (preferentially expressed antigen in melanoma [PRAME], HMGA2, ETS variant 4 [ETV4], MEX3A, TM7SF2, SLC19A1, and tweety-homologs 3 [TTYH3]) displayed significantly elevated expression in HPV-negative cervical cancer cells and HPV-negative cervical cancer tissues. Additionally, higher expression of MEX3A and TTYH3 was associated with a shorter overall survival of patients with HPV-negative cervical cancer. Our study implies that these seven genes are more likely to provide novel insights into the occurrence and progression of HPV-negative cervical cancer.

Tweety-Homolog 1 Facilitates Pain via Enhancement of Nociceptor Excitability and Spinal Synaptic Transmission

Tweety-homolog 1 (Ttyh1) is expressed in neural tissue and has been implicated in the generation of several brain diseases. However, its functional significance in pain processing is not understood. By disrupting the gene encoding Ttyh1, we found a loss of Ttyh1 in nociceptors and their central terminals in Ttyh1-deficient mice, along with a reduction in nociceptor excitability and synaptic transmission at identified synapses between nociceptors and spinal neurons projecting to the periaqueductal grey (PAG) in the basal state. More importantly, the peripheral inflammation-evoked nociceptor hyperexcitability and spinal synaptic potentiation recorded in spinal-PAG projection neurons were compromised in Ttyh1-deficient mice. Analysis of the paired-pulse ratio and miniature excitatory postsynaptic currents indicated a role of presynaptic Ttyh1 from spinal nociceptor terminals in the regulation of neurotransmitter release. Interfering with Ttyh1 specifically in nociceptors produces a comparable pain relief. Thus, in this study we demonstrated that Ttyh1 is a critical determinant of acute nociception and pain sensitization caused by peripheral inflammation.

Super-variants identification for brain connectivity

Identifying genetic biomarkers for brain connectivity helps us understand genetic effects on brain function. The unique and important challenge in detecting associations between brain connectivity and genetic variants is that the phenotype is a matrix rather than a scalar. We study a new concept of super‐variant for genetic association detection. Similar to but different from the classic concept of gene, a super‐variant is a combination of alleles in multiple loci but contributing loci can be anywhere in the genome. We hypothesize that the super‐variants are easier to detect and more reliable to reproduce in their associations with brain connectivity. By applying a novel ranking and aggregation method to the UK Biobank databases, we discovered and verified several replicable super‐variants. Specifically, we investigate a discovery set with 16,421 subjects and a verification set with 2,882 subjects, where they are formed according to release date, and the verification set is used to validate the genetic associations from the discovery phase. We identified 12 replicable super‐variants on Chromosomes 1, 3, 7, 8, 9, 10, 12, 15, 16, 18, and 19. These verified super‐variants contain single nucleotide polymorphisms that locate in 14 genes which have been reported to have association with brain structure and function, and/or neurodevelopmental and neurodegenerative disorders in the literature. We also identified novel loci in genes RSPO2 and TMEM74 which may be upregulated in brain issues. These findings demonstrate the validity of the super‐variants and its capability of unifying existing results as well as discovering novel and replicable results.

Tunneling Nanotubes and Tumor Microtubes in Cancer

Intercellular communication among cancer cells and their microenvironment is crucial to disease progression. The mechanisms by which communication occurs between distant cells in a tumor matrix remain poorly understood. In the last two decades, experimental evidence from different groups proved the existence of thin membranous tubes that interconnect cells, named tunneling nanotubes, tumor microtubes, cytonemes or membrane bridges. These highly dynamic membrane protrusions are conduits for direct cell-to-cell communication, particularly for intercellular signaling and transport of cellular cargo over long distances. Tunneling nanotubes and tumor microtubes may play an important role in the pathogenesis of cancer. They may contribute to the resistance of tumor cells against treatments such as surgery, radio- and chemotherapy. In this review, we present the current knowledge about the structure and function of tunneling nanotubes and tumor microtubes in cancer and discuss the therapeutic potential of membrane tubes in cancer treatment.

Prominin-1 Modulates Rho/ROCK-Mediated Membrane Morphology and Calcium-Dependent Intracellular Chloride Flux

Membrane morphology is an important structural determinant as it reflects cellular functions. The pentaspan membrane protein Prominin-1 (Prom1/CD133) is known to be localised to protrusions and plays a pivotal role in migration and the determination of cellular morphology; however, the underlying mechanism of its action have been elusive. Here, we performed molecular characterisation of Prom1, focussing primarily on its effects on cell morphology. Overexpression of Prom1 in RPE-1 cells triggers multiple, long, cholesterol-enriched fibres, independently of actin and microtubule polymerisation. A five amino acid stretch located at the carboxyl cytosolic region is essential for fibre formation. The small GTPase Rho and its downstream Rho-associated coiled-coil-containing protein kinase (ROCK) are also essential for this process, and active Rho colocalises with Prom1 at the site of initialisation of fibre formation. In mouse embryonic fibroblast (MEF) cells we show that Prom1 is required for chloride ion efflux induced by calcium ion uptake, and demonstrate that fibre formation is closely associated with chloride efflux activity. Collectively, these findings suggest that Prom1 affects cell morphology and contributes to chloride conductance.

High Expression of TTYH3 is Related to Poor Clinical Outcomes in Human Gastric Cancer

Ion channels play important roles in regulating various cellular processes and malignant transformation. Expressions of some chloride channels have been suggested to be associated with patient survival in gastric cancer (GC). However, little is known about the expression and function of TTYH3, a gene encoding a chloride ion channel, in cancer progression. Here, we comprehensively analyzed the expression of TTYH3 and its clinical outcome in GC using publicly available cancer gene expression and patient survival data through various databases. We examined the differences of TTYH3 expression between cancers and their normal tissues using the Oncomine, UALCAN, and GEO (Gene Expression Omnibus) databases. TTYH3 expression was investigated from immunohistochemistry images using the Human Protein Atlas database. Copy number alterations and mutations of TTYH3 were analyzed using cBioPortal. The co-expression profile of TTYH3 in GC was revealed using Oncomine. The gene ontology and pathway analyses were done using those co-expressed genes via the Enrichr tool to explore the predicted signaling pathways in GC. TTYH3 mRNA and protein levels in GC were significantly greater than those in normal tissue. Kaplan–Meier analysis revealed the upregulation of TTYH3 expression, which was significantly correlated with worse patient survival. Collectively, our data suggest that TTYH3 might be a potential prognostic marker for GC patients.

Histological Observation of Teratogenic Phenotypes Induced in Frog Embryo Assays

Amphibian embryos have long served as an ideal model for teratogenicity testing. While whole-mount embryo observations can be utilized, histological observation of teratogenic phenotypes provides a wealth of additional information that can lead to mechanistic insights. In this chapter, detailed protocols for two methods of sectioning embryos as well as a guide for histological analysis is provided.

Rare copy number variants in the genome of Chinese female children and adolescents with Turner syndrome

Turner syndrome (TS) is a congenital disease caused by complete or partial loss of one X chromosome. Low bone mineral status is a major phenotypic characteristic of TS that can not be fully explained by X chromosome loss, suggesting other autosomal-linked mutations may also exist. Therefore, the present study aimed to detect potential genetic mutations in TS through examination of copy number variation (CNV). Seventeen patients with TS and 15 healthy volunteer girls were recruited. Array-based comparative genomic hybridization (a-CGH) was performed on whole blood genomic DNA (gDMA) from the 17 TS patients and 15 healthy volunteer girls to identify potential CNVs. The abnormal CNV of one identified gene (CARD11) was verified by quantitative PCR. All cases diagnosed had TS based on genotype examination and physical characteristics, including short stature and premature ovarian failure. Three rare CNVs, located individually at 7p22.3, 7p22.2, and Xp22.33, where six genes (TTYH3, AMZ1, GNA12, BC038729, CARD11, and SHOX (stature homeobox)) are located, were found in TS patients. Quantitative PCR confirmed the CNV of CARD11 in the genome of TS patients. Our results indicate that CARD11 gene is one of the mutated genes involved in TS disease. However, this CNV is rare and its contribution to TS phenotype requires further study.

Tweety-Homolog 1 Drives Brain Colonization of Gliomas

Early and progressive colonization of the healthy brain is one hallmark of diffuse gliomas, including glioblastomas. We recently discovered ultralong (>10 to hundreds of microns) membrane protrusions [tumor microtubes (TMs)] extended by glioma cells. TMs have been associated with the capacity of glioma cells to effectively invade the brain and proliferate. Moreover, TMs are also used by some tumor cells to interconnect to one large, resistant multicellular network. Here, we performed a correlative gene-expression microarray and in vivo imaging analysis, and identified novel molecular candidates for TM formation and function. Interestingly, these genes were previously linked to normal CNS development. One of the genes scoring highest in tests related to the outgrowth of TMs was tweety-homolog 1 (TTYH1), which was highly expressed in a fraction of TMs in mice and patients. Ttyh1 was confirmed to be a potent regulator of normal TM morphology and of TM-mediated tumor-cell invasion and proliferation. Glioma cells with one or two TMs were mainly responsible for effective brain colonization, and Ttyh1 downregulation particularly affected this cellular subtype, resulting in reduced tumor progression and prolonged survival of mice. The remaining Ttyh1-deficient tumor cells, however, had more interconnecting TMs, which were associated with increased radioresistance in those small tumors. These findings imply a cellular and molecular heterogeneity in gliomas regarding formation and function of distinct TM subtypes, with multiple parallels to neuronal development, and suggest that Ttyh1 might be a promising target to specifically reduce TM-associated brain colonization by glioma cells in patients.SIGNIFICANCE STATEMENT In this report, we identify tweety-homolog 1 (Ttyh1), a membrane protein linked to neuronal development, as a potent driver of tumor microtube (TM)-mediated brain colonization by glioma cells. Targeting of Ttyh1 effectively inhibited the formation of invasive TMs and glioma growth, but increased network formation by intercellular TMs, suggesting a functional and molecular heterogeneity of the recently discovered TMs with potential implications for future TM-targeting strategies.

Variable developmental delays and characteristic facial features-A novel 7p22.3p22.2 microdeletion syndrome?

Isolated 7p22.3p22.2 deletions are rarely described with only two reports in the literature. Most other reported cases either involve a much larger region of the 7p arm or have an additional copy number variation. Here, we report five patients with overlapping microdeletions at 7p22.3p22.2. The patients presented with variable developmental delays, exhibiting relative weaknesses in expressive language skills and relative strengths in gross, and fine motor skills. The most consistent facial features seen in these patients included a broad nasal root, a prominent forehead a prominent glabella and arched eyebrows. Additional variable features amongst the patients included microcephaly, metopic ridging or craniosynostosis, cleft palate, cardiac defects, and mild hypotonia. Although the patients' deletions varied in size, there was a 0.47 Mb region of overlap which contained 7 OMIM genes: EIP3B, CHST12, LFNG, BRAT1, TTYH3, AMZ1, and GNA12. We propose that monosomy of this region represents a novel microdeletion syndrome. We recommend that individuals with 7p22.3p22.2 deletions should receive a developmental assessment and a thorough cardiac exam, with consideration of an echocardiogram, as part of their initial evaluation.

Expression and purification of mouse Ttyh1 fragments as antigens to generate Ttyh1-specific monoclonal antibodies

Ttyh1 is a murine homolog of the Drosophila Tweety and is predicted as a five-pass transmembrane protein. The Ttyh1 mRNA is expressed in mouse brain tissues with a restricted pattern and in human glioma cells. Ttyh1 protein may function as a large-conductance chloride channel, however, the role of Ttyh1 in normal neural development and tumorigenesis has been largely unknown, at least partially due to the lack of effective antibodies. Here we report the expression in E. coli and purification of two recombinant Ttyh1 protein fragments corresponding to one of the predicted extracellular domains and the carboxyl terminus of the mouse Ttyh1. With these Ttyh1 protein products, a set of monoclonal antibodies (mAbs) against the mouse Ttyh1 protein was established by using conventional hybridoma techniques. The specificity of the anti-Ttyh1 mAbs was determined based on their activities in Western blotting and immunofluorescent analysis using embryonic brain tissues and cultured mouse neural stem cells (NSCs). We also show that the mouse Ttyh1 protein was expressed in cultured NSCs, most likely in membrane and cytoplasm. In mouse embryonic brains, it appeared that the Ttyh1 protein was specifically expressed in the apical edge of the ventricular zone as puncta-like structures, as determined by using immunofluorescence. Taken together, our study provided a useful tool for further exploration of the biological functions and pathological significance of Ttyh1 in mice.