Enhanced long-term potentiation and impaired learning in mice lacking alternative exon 33 of CaV1.2 calcium channel

The CACNA1C (calcium voltage-gated channel subunit alpha 1 C) gene that encodes the CaV1.2 channel is a prominent risk gene for neuropsychiatric and neurodegenerative disorders with cognitive and social impairments like schizophrenia, bipolar disorders, depression and autistic spectrum disorders (ASD). We have shown previously that mice with exon 33 deleted from CaV1.2 channel (CaV1.2-exon 33−/−) displayed increased CaV1.2 current density and single channel open probability in cardiomyocytes, and were prone to develop arrhythmia. As Ca2+ entry through CaV1.2 channels activates gene transcription in response to synaptic activity, we were intrigued to explore the possible role of Cav1.2Δ33 channels in synaptic plasticity and behaviour. Homozygous deletion of alternative exon 33 resulted in enhanced long-term potentiation (LTP), and lack of long- term depression (LTD), which did not correlate with enhanced learning. Exon 33 deletion also led to a decrease in social dominance, sociability and social novelty. Our findings shed light on the effect of gain-of-function of CaV1.2Δ33 signalling on synaptic plasticity and behaviour and provides evidence for a link between CaV1.2 and distinct cognitive and social behaviours associated with phenotypic features of psychiatric disorders like schizophrenia, bipolar disorder and ASD.

Case Report: A Chinese Family of Woodhouse-Sakati Syndrome With Diabetes Mellitus, With a Novel Biallelic Deletion Mutation of the DCAF17 Gene

Woodhouse–Sakati syndrome (WSS) (OMIM#241080) is a rare multi-system autosomal recessive disease with homozygous mutation of the DCAF17 gene. The main features of WSS include diabetes, hypogonadism, alopecia, deafness, intellectual disability and progressive extrapyramidal syndrome. We identified a WSS family with a novel DCAF17 gene mutation type in China. Two unconsanguineous siblings from the Chinese Han family exhibiting signs and symptoms of Woodhouse-Sakati syndrome were presented for evaluation. Whole-exome sequencing revealed a homozygous deletion NM_025000.4:c.1488_1489delAG in the DCAF17 gene, which resulted in a frameshift mutation that led to stop codon formation. We found that the two patients exhibited low insulin and C-peptide release after glucose stimulation by insulin and C-peptide release tests. These findings indicate that the DCAF17 gene mutation may cause pancreatic β cell functional impairment and contribute to the development of diabetes.

The Role of Sorting Nexin 17 in Cardiac Development

Sorting nexin 17 (SNX17), a member of sorting nexin (SNX) family, acts as a modulator for endocytic recycling of membrane proteins. Results from our previous study demonstrated the embryonic lethality of homozygous defect of SNX17. In this study, we investigated the role of SNX17 in rat fetal development. Specifically, we analyzed patterns of SNX17 messenger RNA (mRNA) expression in multiple rat tissues and found high expression in the cardiac outflow tract (OFT). This expression was gradually elevated during the cardiac OFT morphogenesis. Homozygous deletion of the SNX17 gene in rats resulted in mid-gestational embryonic lethality, which was accompanied by congenital heart defects, including the double-outlet right ventricle and atrioventricular and ventricular septal defects, whereas heterozygotes exhibited normal fetal development. Moreover, we found normal migration distance and the number of cardiac neural crest cells during the OFT morphogenesis. Although cellular proliferation in the cardiac OFT endocardial cushion was not affected, cellular apoptosis was significantly suppressed. Transcriptomic profiles and quantitative real-time PCR data in the cardiac OFT showed that SNX17 deletion resulted in abnormal expression of genes associated with cardiac development. Overall, these findings suggest that SNX17 plays a crucial role in cardiac development.

Discovering the chlamydospore regulatory network in Candida albicans

A normal resident of healthy humans and warm-blooded animals, C. albicans is a commensal fungus that is also among the most common opportunistic pathogens of humans. C. albicans forms unique morphological structures called chlamydospores, which are large, spherical, thick-walled structures formed at the ends of hyphae that have unknown biological function. My goal is to discover the regulatory network controlling chlamydospore formation in C. albicans. By determining this network, we can gain insight into the biological roles of chlamydospores in the C. albicans lifestyle, better understand C. albicans morphological transitions, and determine the selective advantage (if any) provided by chlamydospores to this pathogenic fungus. To determine this regulatory network, I have screened a library of 211 C. albicans transcription factor (TF) homozygous deletion mutants to assay for their abilities to form chlamydospores under standard chlamydospore-inducing growth conditions. I have identified seven TF mutants that fail to produce any chlamydospores andthree TF mutants that produce high levels of chlamydospores relative to WT. To characterize the transcriptional changes occurring during chlamydospore formation, I have performed RNA sequencing (RNA-seq) on these identified regulator mutants to uncover the differentially regulated target genes of each chlamydospore regulator. I will use genome-wide chromatin immunoprecipitation followed by sequencing (ChIP-seq) on epitope-tagged versions of these regulators to determine which genes are directly under the control of each TF. RNA-seq coupled with ChIP-seq will allow me to determine the regulatory network controlling chlamydospore formation in C. albicans.

Knockdown and Knockout of Tissue Factor Pathway Inhibitor in Zebrafish

Tissue Factor Pathway Inhibitor (TFPI) is an anticoagulant that inhibits factor VIIa and Xa in the blood coagulation pathways. TFPI contains three Kunitz domains, K1, K2, and K3. K1 and K2 inhibit factor VIIa and Xa, respectively. However, the regulation of TFPI is poorly studied. Since zebrafish has become an alternate model to discover novel actors in hemostasis, we hypothesized that TFPI regulation could be studied using this model. As a first step, we confirmed the presence of tfpia in zebrafish using RT-PCR. We then performed piggyback knockdowns of tfpia and found increased coagulation activity in tfpia knockdown. We then created a deletion mutation in tfpia locus using CRISPR/Cas9 method. The tfpia homozygous deletion mutants showed increased coagulation activities similar to that found in tfpia knockdown. Taken together, our data suggest that tfpia is a negative regulator for zebrafish coagulation, and silencing it leads to thrombotic phenotype. Also, the zebrafish tfpia knockout model could be used for reversing this thrombotic phenotype to identify antithrombotic novel factors by the genome-wide piggyback knockdown method.

Correlation of MTAP Immunohistochemistry With CDKN2A Status Assessed by Fluorescence In Situ Hybridization and Clinicopathological Features in CNS WHO Grade 2 and 3 Meningiomas: A Single Center Cohort Study

CDKN2A homozygous deletion has occasionally been reported in atypical and anaplastic meningiomas and is considered as one of the genetic alterations commonly involved in their recurrence and malignant progression. Methylthioadenosine phosphorylase (MTAP) immunohistochemistry is a promising surrogate marker for CDKN2A homozygous deletion in different cancers but has not been examined in meningiomas. We performed CDKN2A FISH and MTAP immunohistochemistry on specimens from 30 patients with CNS WHO grade 2 (n = 27) and 3 (n = 3) meningiomas, including specimens from primary and recurrent tumors and then determined whether MTAP immunohistochemistry correlated with CDKN2A homozygous deletion and clinicopathological features. CDKN2A homozygous deletion was detected in 12% (3/26) of CNS WHO grade 2 and 67% (2/3) of CNS WHO grade 3 meningiomas; 3 cases exhibited temporal and/or spatial heterogeneity. MTAP loss was in excellent concordance with CDKN2A homozygous deletion (sensitivity; 100%, specificity; 100%). MTAP loss/CDKN2A homozygous deletion correlated with cellular proliferation (mitotic rate; p = 0.001, Ki-67 labeling index; p = 0.03) and poor prognosis (overall survival; p = 0.01, progression free survival; p < 0.001). Thus, MTAP immunostaining can be a surrogate marker for CDKN2A homozygous deletion in meningiomas, and MTAP loss/CDKN2A homozygous deletion may be an important prognostic factor for meningiomas.

Novel SNX13 Frameshift Variant in an Individual with Developmental Delay

Recently, an increasing number of genes have been associated with global developmental delay (GDD) and intellectual disability (ID). The sorting nexin (SNX) protein family plays multiple roles in protein trafficking and intracellular signaling. SNXs have been reported to be associated with several disorders, including Alzheimer disease and Down syndrome. Despite the growing evidence of an association of SNXs with neurodegeneration, SNX13 deficiency has not been associated with GDD or ID. In this study, we present the case of a 4-year-old boy with brain dysplasia and GDD, including language delay, cognitive delay, and dyskinesia. Exome sequencing revealed a 1-bp homozygous deletion in <i>SNX13</i> (NM_015132.5: exon8: c.742_743del; p.Tyr248Leufs*20), which caused a frameshift and predicted early termination. Sanger sequencing confirmed that the variant was inherited from his parents respectively. Our findings associate <i>SNX13</i> variation with GDD for the first time and provide a new GDD candidate gene.

Molecular and phenotypic characteristics of 15q24 microdeletion in pediatric patients with developmental disorders

Chromosome 15q24 microdeletion is a rare genetic disorder characterized by development delay, facial dysmorphism, congenital malformations, and occasional autism spectrum disorder (ASD). In this study, we identified five cases of 15q24 microdeletion using multiplex ligation-dependent probe amplification (MLPA) technology in a cohort of patients with developmental delay and/or intellectual disability. Two of these five cases had deletions that overlapped with the previously defined 1.1 Mb region observed in most reported cases. Two cases had smaller deletions (< 0.57 Mb) in the 15q24.1 low copy repeat (LCR) B-C region. They presented significant neurobehavioral features, suggesting that this smaller interval is critical for core phenotypes of 15q24 microdeletion syndrome. One case had minimal homozygous deletion of less than 0.11 Mb in the 15q24.1 LCR B-C region, which contained CYP1A1 (cytochrome P450 family 1 subfamily A member 1) and EDC3 (enhancer of mRNA decapping 3) genes, resulting in poor immunity, severe laryngeal stridor, and lower limbs swelling. This study provides additional evidence of 15q24 microdeletion syndrome with genetic and clinical findings. The results will be of significance to pediatricians in their daily practice.

MPC-10 Prognostic analysis in IDH mutant astrocytoma patient with CDKN2A/B homozygous deletion

background: IDH mutant astrocytoma has good prognosis compared with IDH wildtype one. In IDH mutant astrocytoma, However, patients with CDKN2A/B homozygous deletion (HD) are worse prognosis than non CDKN2A/B HD. Here we analyzed the prognosis of glioma patients identified with CDKN2A/B HD in our hospital. method: There were 62 cases, and female was 26. Mean age of all cases was 41.2 and median age was 38. In IDH gene status, R132H was 59 cases (95.2%), R172K 2 (3.2%) and R132S 1 (1.6%). All 62 cases were TERT wildtype. CDKN2A/B HD were 12 cases (19.4%). In log-rank test, the group of CDKN2A/B HD was poor prognosis than non HD. In astrocytoma grade 3, CDKN2A/B HD had significantly poor prognosis (p=0.002). In Cox proportional hazard model analysis, CDKN2A/B HD was effective predictive prognostic factor as well as age and grading (p=0.03). discussion/conclusion: We showed that CDKN2A/B HD was good predictive prognostic factor in IDH mutant astrocytoma.