The interaction of endorepellin and neurexin triggers neuroepithelial autophagy and maintains neural tube development.

Heparan sulfate proteoglycan 2 (HSPG2) gene encodes the matrix protein Perlecan, and genetic inactivation of this gene creates mice that are embryonic lethal with severe neural tube defects (NTDs). We discovered rare genetic variants of HSPG2 in 10% cases compared to only 4% in controls among a cohort of 369 NTDs. Endorepellin, a peptide cleaved from the domain V of Perlecan, is known to promote angiogenesis and autophagy in endothelial cells. The roles of enderepellin in neurodevelopment remain unclear so far. Our study revealed that endorepellin can migrate to the neuroepithelial cells and then be recognized and bind with the neuroepithelia receptor neurexin in vivo. Through the endocytic pathway, the interaction of endorepellin and neurexin physiologically triggers autophagy and appropriately modulates the differentiation of neural stem cells into neurons as a blocker, which is necessary for normal neural tube closure. We created knock-in (KI) mouse models with human-derived HSPG2 variants, using sperm-like stem cells that had been genetically edited by CRISPR/Cas9. We realized that any HSPG2 variants that affected the function of endorepellin were considered pathogenic causal variants for human NTDs given that the severe NTD phenotypes exhibited by these KI embryos occurred in a significantly higher response frequency compared to wildtype embryos. Our study provides a paradigm for effectively confirming pathogenic mutations in other genetic diseases. Furthermore, we demonstrated that using autophagy inhibitors at a cellular level can repress neuronal differentiation. Therefore, autophagy agonists may prevent NTDs resulting from failed autophagy maintenance and neuronal over-differentiation caused by deleterious endorepellin variants.

miR-377-3p Regulates Hippocampal Neurogenesis via the Zfp462-Pbx1 Pathway and Mediates Anxiety-Like Behaviors in Prenatal Hypoxic Offspring.

Prenatal hypoxia (PH) is one of the most common complications of obstetrics and is closely associated with many neurological disorders such as depression, anxiety, and cognitive impairment. Our previous study found that Zfp462 heterozygous (Het) mice exhibit significant anxiety-like behavior. Interestingly, offspring mice with PH also have anxiety-like behaviors in adulthood, accompanied by reduced expression of Zfp462 and increased expression of miR-377-3p; however, the exact regulatory mechanisms remain unclear. In this study, western blotting, gene knockdown, immunofluorescence, dual-luciferase reporter assay, immunoprecipitation, cell transfection with miR-377-3p mimics or inhibitors, quantitative real-time PCR, and rescue assay were used to detect changes in the miR-377-3p-Zfp462-Pbx1 (pre-B-cell leukemia homeobox1) pathway in the brains of prenatal hypoxic offspring to explain the pathogenesis of anxiety-like behaviors. We found that Zfp462 deficiency promoted Pbx1 protein degradation through ubiquitination and that Zfp462 Het mice showed downregulation of the protein kinase B (PKB, also called Akt)-glycogen synthase kinase-3ß (GSK3ß)-cAMP response element-binding protein (CREB) pathway and hippocampal neurogenesis with anxiety-like behavior. In addition, PH mice exhibited upregulation of miR-377-3p, downregulation of Zfp462/Pbx1-Akt-GSK3ß-CREB pathway activity, reduced hippocampal neurogenesis, and an anxiety-like phenotype. Intriguingly, miR-377-3p directly targets the 3'UTR of Zfp462 mRNA to regulate Zfp462 expression. Importantly, microinjection of miR-377-3p antagomir into the hippocampal dentate gyrus of PH mice upregulated Zfp462/Pbx1-Akt-GSK3ß-CREB pathway activity, increased hippocampal neurogenesis, and improved anxiety-like behaviors. Collectively, our findings demonstrated a crucial role for miR-377-3p in the regulation of hippocampal neurogenesis and anxiety-like behaviors via the Zfp462/Pbx1-Akt-GSK3ß-CREB pathway. Therefore, miR-377-3p could be a potential therapeutic target for anxiety-like behavior in prenatal hypoxic offspring.

Deficiency of Wdr60 and Wdr34 cause distinct neural tube malformation phenotypes in early embryos.

Cilia are specialized organelles that extend from plasma membrane, functioning as antennas for signal transduction and are involved in embryonic morphogenesis. Dysfunction of cilia lead to many developmental defects, including neural tube defects (NTDs). Heterodimer WDR60-WDR34 (WD repeat domain 60 and 34) are intermediate chains of motor protein dynein-2, which play important roles in ciliary retrograde transport. It has been reported that disruption of Wdr34 in mouse model results in NTDs and defects of Sonic Hedgehog (SHH) signaling. However, no Wdr60 deficiency mouse model has been reported yet. In this study, piggyBac (PB) transposon is used to interfere Wdr60 and Wdr34 expression respectively to establish Wdr60 PB/PB and Wdr34 PB/PB mouse models. We found that the expression of Wdr60 or Wdr34 is significantly decreased in the homozygote mice. Wdr60 homozygote mice die around E13.5 to E14.5, while Wdr34 homozygote mice die around E10.5 to E11.5. WDR60 is highly expressed in the head region at E10.5 and Wdr60 PB/PB embryos have head malformation. RNAseq and qRT-PCR experiments revealed that Sonic Hedgehog signaling is also downregulated in Wdr60 PB/PB head tissue, demonstrating that WDR60 is also required for promoting SHH signaling. Further experiments on mouse embryos also revealed that the expression levels of planar cell polarity (PCP) components such as CELSR1 and downstream signal molecule c-Jun were downregulated in WDR34 homozygotes compared to wildtype littermates. Coincidently, we observed much higher ratio of open cranial and caudal neural tube in Wdr34 PB/PB mice. CO-IP experiment showed that WDR60 and WDR34 both interact with IFT88, but only WDR34 interacts with IFT140. Taken together, WDR60 and WDR34 play overlapped and distinct functions in modulating neural tube development.

Detection of anabolic androgenic steroids in serum samples.

When testing for anabolic androgenic steroids (AAS) outside sports communities, for example, in healthcare and forensic medicine, urine is the matrix of choice. However, there are drawbacks with urinary sampling, and serum might be useful as a complementary matrix. The aim was to develop an LC-MS/MS method for serum measuring AAS frequently used outside of sport, including testosterone (T), steroid esters, and eight other synthetic AAS. The sample pretreatment included sample precipitation and evaporation. Limit of quantification for the AAS was 0.05-0.5 ng/mL, and linearity was 0.05-20 ng/mL for most of the substances. Generally, the within- and between-day CV results, matrix effect, and process efficiency were <15%. The AAS were stable for at least 6 months at -20°C. Serum samples were obtained from previous studies. A novel finding from an administration study was that T enanthate was present in serum even after 5 years of storage at -20°C. Serum samples from self-reporting AAS individuals, where T esters were detected, were positive for testosterone using the urinary testosterone/epitestosterone criterion >10. Of those identified as positive in traditional urinary doping tests (n = 15), AAS in serum were found in 80% of the subjects. Our results show that serum may be a valid complementary matrix to urine samples for AAS testing.

Validation of an automated UPLC-MS/MS method for methylmalonic acid in serum/plasma and its application on clinical samples.

Vitamin B12 is essential for cell function and only accessible in food for mammals. To monitor vitamin B12 deficiency, methylmalonic acid (MMA) is used. Since MMA in serum/plasma is a frequently requested analyte at clinical laboratories the analytical method was improved and validated on a 96 well plate. Using a Tecan robot a working solution of acetonitrile containing MMA-D3 was added to plasma/serum samples. The solution was shaken for 1 min and then centrifuged for 10min. The supernatant was transferred to another plate and evaporated with nitrogen gas. The residual was redissolved with 0.2% formic acid in MilliQ-water and the plate was shaken for 1 min prior to LC-MS/MS analysis. The total analysis time was 3 min, retention time for MMA was 1.1 min and it was well separated from the interfering succinic acid. The calibrator curve was 0.044 - 1.63 µmol/L, which was also the linear range and LLOQ was 0.044 µmol/L. The within- and between-run CV:s were 3-7%. Age dependent clinical cut-offs at 0.28 (age <50 years) and 0.36 µmol/L (age ≥50 years) were applied. In 404 clinical routine samples 10% were >0.28, 7% > 0.4, and only 1% were >0.7 µmol/L. The method has been successfully implemented in the laboratory for routine MMA analysis.

Parental folate deficiency induces birth defects in mice accompanied with increased de novo mutations.

Dietary folate deficiency (FD) is associated with the occurrence of birth defects. However, the mechanisms underlying this association remain elusive. In particular, how FD affects genome stability is unknown. To examine whether a folate-deficient diet can affect genome stability, C57BL/6 mice were maintained on a synthetic diet lacking of folic acid (FA) for two generations. F0 mice received the FD diet beginning at 3 weeks of age, and their offspring (F1) began the FD diet after weaning. Both male and female F1 mice fed the FD diet were intentionally crossed with F1 mice fed the normal diet to produce F2 mice. F2 embryos were dissected and collected at E14.5 and E18.5. The malformation ratio was significantly increased in F2 embryos fed the FD diet for two generations compared to those fed the normal diet. Whole-genome sequencing of multiple sibship with F1 males on the FD diet showed that the de novo mutation (DNM) rate in F2 embryos was three times of the reported spontaneous rate in mice. Furthermore, many DNMs observed in the F2 mice exhibited an allele ratio of 1:3 instead of 2:2, suggesting that these mutations are likely to accumulate in gamete cells as a form of mismatch in the DNA duplex. Our study indicated that FD for two generations significantly enhances DNM accumulation during meiosis, which might contribute to the increased negative birth outcomes among F2 mice. Not only maternal but also paternal FA supplementation is probably also necessary and beneficial to prevent birth defects.

High glucose causes developmental abnormalities in neuroepithelial cysts with actin and HK1 distribution changes.

It has been reported that the offspring of diabetic pregnant women have an increased risk for neural tube defects. Previous studies in animal models suggested that high glucose induces cell apoptosis and epigenetic changes in the developing neural tube. However, effects on other cellular aspects such as the cell shape changes were not fully investigated. Actin dynamics plays essential roles in cell shape change. Disruption on actin dynamics is known to cause neural tube defects. In the present study, we used a 3D neuroepithelial cyst model and a rosette model, both cultured from human embryonic stem cells, to study the cellular effects caused by high glucose. By using these models, we observed couple of new changes besides increased apoptosis. First, we observed that high glucose disturbed the distribution of pH3 positive cells in the neuroepithelial cysts. Secondly, we found that high glucose exposure caused a relatively smaller actin inner boundary enclosed area, which was unlikely due to osmolarity changes. We further investigated key glucose metabolic enzymes in our models and the results showed that the distribution of hexokinase1 (HK1) was affected by high glucose. We observed that hexokinase1 has an apical-basal polarized distribution and is highest next to actin at the boundaries. hexokinase1 was more diffused and distributed less polarized under high glucose condition. Together, our observations broadened the cellular effects that may be caused by high glucose in the developing neural tube, especially in the secondary neurulation process.

MeCP2 duplication causes hyperandrogenism by upregulating LHCGR and downregulating RORα.

Duplication of MECP2 (methyl-CpG-binding protein 2) gene causes a serious neurological and developmental disorder called MECP2 duplication syndrome (MDS), which is usually found in males. A previous clinical study reported that MDS patient has precocious puberty with hyperandrogenism, suggesting increased MeCP2 may cause male hyperandrogenism. Here we use an MDS mouse model and confirm that MECP2 duplication significantly upregulates androgen levels. We show for the first time that MeCP2 is highly expressed in the Leydig cells of testis, where androgen is synthesized. Mechanistically, MECP2 duplication increases androgen synthesis and decreases androgen to estrogen conversion through either the upregulation of luteinizing hormone receptor (LHCGR) in testis, as a result of MeCP2 binds to G-quadruplex structure of Lhcgr promoter and recruits the transcription activator CREB1 or the downregulation of the expression of aromatase in testis by binding the CpG island of Rorα, an upstream regulator of aromatase. Taken together, we demonstrate that MeCP2 plays an important role in androgen synthesis, supporting a novel non-CNS function of MeCP2 in the process of sex hormone synthesis.

Organoids as a new model system to study neural tube defects.

The neural tube is the first critically important structure that develops in the embryo. It serves as the primordium of the central nervous system; therefore, the proper formation of the neural tube is essential to the developing organism. Neural tube defects (NTDs) are severe congenital defects caused by failed neural tube closure during early embryogenesis. The pathogenesis of NTDs is complicated and still not fully understood even after decades of research. While it is an ethically impossible proposition to investigate the in vivo formation process of the neural tube in human embryos, a newly developed technology involving the creation of neural tube organoids serves as an excellent model system with which to study human neural tube formation and the occurrence of NTDs. Herein we reviewed the recent literature on the process of neural tube formation, the progress of NTDs investigations, and particularly the exciting potential to use neural tube organoids to model the cellular and molecular mechanisms underlying the etiology of NTDs.

SRPS associated protein WDR60 regulates the multipolar-to-bipolar transition of migrating neurons during cortical development.

Mutations of WD40 repeat domain 60 (WDR60) have been identified in short-rib polydactyly syndromes (SRPS I-V), a group of lethal congenital disorders characterized by short ribs, polydactyly, and a range of extraskeletal phenotypes. However, the underlying mechanism is still unclear. Here, we report that WDR60 is essential for embryonic development and plays a critical role in the multipolar-bipolar transition and migration of newborn neurons during brain development. Mechanically, we found that WDR60 was located at the microtubule-organizing center to control microtubule organization and possibly, the trafficking of cellular components. Importantly, the migration defect caused by Wdr60 knockdown could be rescued by the stable form of α-Tubulin, α-TubulinK40Q (an acetylation-mimicking mutant). These findings identified a non-cilia function of WDR60 and provided insight into its biological function, as well as the pathogenesis of WDR60 deficiency associated with SRPS.

Detection of Drugs in Oral Fluid Samples Using a Commercially Available Collection Device: Agreement with Urine Testing and Evaluation of A and B Samples Obtained from Employees at Different Workplace Settings with Uncontrolled Sampling Procedures.

The use of oral fluid tests to detect drugs is of growing interest in various areas, including treatment centers, roadside and workplace testing. In this study, we investigated drug detection in oral fluid samples collected using a commercially available device, Oral Eze. Drug detection in oral fluid was compared to paired urine samples, which were simultaneously collected. We also evaluated the collection device by comparing A and B oral fluid samples. Finally, we studied the stability of various drugs in samples stored for at least 1 year. The drug profile was investigated by comparing the drugs detected in oral fluid samples with paired urine samples collected in a treatment center. A total of 113 paired oral fluid and urine samples were investigated for the presence of drugs in the following groups: amphetamines, benzodiazepines, opiates and opioids, cocaine and cannabis. A and B samples were collected from different workplaces through an uncontrolled sampling procedure (n = 76). The stability of drugs in A samples was assessed after storage at -20°C for 1 year. Generally, there was a good correlation between drugs detected in oral fluid samples and urine samples. The heroin metabolite, 6-MAM, was more frequently detected in oral fluid samples than in urine samples, while cannabis was better detected in urine samples. Drugs in oral fluid samples were stable when stored at -20°C for at least 1 year. However, in many positive A and B oral fluid samples, there was significant variation in the concentrations obtained. Hence, the collection device may need to be further standardized and improved.

CXADR-like membrane protein protects against heart injury by preventing excessive pyroptosis after myocardial infarction.

Myocardial infarction (MI) results in cardiomyocyte death and ultimately leads to heart failure. Pyroptosis is a type of the inflammatory programmed cell death that has been found in various diseased tissues. However, the role of pyroptosis in MI heart remains unknown. Here, we showed that CXADR-like membrane protein (CLMP) was involved in pyroptosis in the mouse MI heart. Our data showed that CLMP was strongly expressed in fibroblasts of the infarcted mouse hearts. The Clmp+/- mice showed more serious myocardial fibrosis and ventricular dysfunction post-MI than wild-type (Clmp+/+ ) mice, indicating a protective effect of the fibroblast-expressed CLMP against MI-induced heart damage. Transcriptome analyses by RNA sequencing indicated that Il-1ß mRNA was significantly increased in the MI heart of Clmp+/- mouse, which indicated a more serious inflammatory response. Meanwhile, cleaved caspase-1 and Gasdermin D were significantly increased in the Clmp+/- MI heart, which demonstrated enhanced pyroptosis in the Clmp knockdown heart. Further analysis revealed that the pyroptosis mainly occurred in cardiac fibroblasts (CFs). Compared to wild-type fibroblasts, Clmp+/- CFs showed more serious pyroptosis and inflammatory after LPS plus nigericin treatment. Collectively, our results indicate that CLMP participates in the pyroptotic and inflammatory response of CFs in MI heart. We have provided a novel pyroptotic insight into the ischaemic heart, which might hold substantial potential for the treatment of MI.

WDR34 mutation from anencephaly patients impaired both SHH and PCP signaling pathways.

Neural tube defects (NTDs) are debilitating human congenital abnormalities due to failure of neural tube closure. Sonic Hedgehog (SHH) signaling is required for dorsal-ventral patterning of the neural tube. The loss of activation in SHH signaling normally causes holoprosencephaly while the loss of inhibition causes exencephaly due to failure in neural tube closure. WDR34 is a dynein intermedia chain component which is required for SHH activation. However, Wdr34 knockout mouse exhibit exencephaly. Here we screened mutations in WDR34 gene in 100 anencephaly patients of Chinese Han population. Compared to 1000 Genome Project data, two potentially disease causing missense mutations of WDR34 gene (c.1177G>A; p.G393S and c.1310A>G; p.Y437C) were identified in anencephaly patients. These two mutations did not affect the protein expression level of WDR34. Luciferase reporter and endogenous target gene expression level showed that both mutations are lose-of-function mutations in SHH signaling. Surprisingly, WDR34 could promote planar cell polarity (PCP) signaling and the G393S lost this promoting effect on PCP signaling. Morpholino knockdown of wdr34 in zebrafish caused severe convergent extension defects and pericardial abnormalities. The G393S mutant has less rescuing effects than both WT and Y437C WDR34 in zebrafish. Our results suggested that mutation in WDR34 could contribute to human NTDs by affecting both SHH and PCP signaling.

Rare mutations in the autophagy-regulating gene AMBRA1 contribute to human neural tube defects.

Neural tube defects (NTDs) are severe congenital malformations caused by failed neural tube closure. Recently, autophagy is revealed to play a vital role in neuroepithelium development and neurulation. Autophagy and beclin 1 regulator 1 (Ambra1) is a crucial regulator of autophagy initiation, and its deficiency in mice leads to exencephaly and/or spina bifida. However, the genetic contribution of AMBRA1 to the etiology of human NTDs remains unknown. In this study, we identified five rare missense mutations of AMBRA1 in 352 NTDs cases, which were absent in 224 matched controls. Western blotting and fluorescence puncta counting for MAP1LC3A/LC3 in HEK293T cells suggested that four of the mutations (AMBRA1 p.Thr80Met, p.Leu274Phe, p.Ser743Phe, and p.Met884Val) affected autophagy initiation to various extents. Furthermore, these four mutations also displayed loss-of-function effects compared with wild-type AMBRA1 when we injected messenger RNA (mRNA) to overexpress or rescue ambra1a-morpholino oligos (MO) knockdown in zebrafish. It is intriguing that trehalose, a natural disaccharide, could rescue ambra1a-MO knockdown in a dose-dependent manner independently or together with AMBRA1 mRNA. Taken together, our findings suggest that rare mutations of the autophagy regulator gene AMBRA1 may contribute to the etiology of human neural tube defects, and trehalose is a promising treatment for a subset of NTDs caused by autophagy impairment.

Substrate-selective protein ectodomain shedding by ADAM17 and iRhom2 depends on their juxtamembrane and transmembrane domains.

The metalloprotease ADAM17 (a disintegrin and metalloprotease 17) regulates EGF-receptor and TNFα signaling, thereby not only protecting the skin and intestinal barrier, but also contributing to autoimmunity. ADAM17 can be rapidly activated by many stimuli through its transmembrane domain (TMD), with the seven membrane-spanning inactive Rhomboids (iRhom) 1 and 2 implicated as candidate regulatory partners. However, several alternative models of ADAM17 regulation exist that do not involve the iRhoms, such as regulation through disulfide bond exchange or through interaction with charged phospholipids. Here, we report that a non-activatable mutant of ADAM17 with the TMD of betacellulin (BTC) can be rescued by restoring residues from the ADAM17 TMD, but only in Adam17-/- cells, which contain iRhoms, not in iRhom1/2-/- cells. We also provide the first evidence that the extracellular juxtamembrane domains (JMDs) of ADAM17 and iRhom2 regulate the stimulation and substrate selectivity of ADAM17. Interestingly, a point mutation in the ADAM17 JMD identified in a patient with Tetralogy of Fallot, a serious heart valve defect, affects the substrate selectivity of ADAM17 toward Heparin-binding epidermal growth factor like growth factor (HB-EGF), a crucial regulator of heart valve development in mice. These findings provide new insights into the regulation of ADAM17 through an essential interaction with the TMD1 and JMD1 of iRhom2.

Author Correction: Threshold for neural tube defect risk by accumulated singleton loss-of-function variants.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The rare mutation in the endosome-associated recycling protein gene VPS50 is associated with human neural tube defects.

BACKGROUND: Tight control of endosome trafficking is essential for the generation of a normally patterned embryo. Recent studies have found that VPS50 is a key ingredient in EARP which is required for recycling of internalized TfRs to the cell surface and dense-core vesicle maturation. However, the role of VPS50 in embryogenesis and human physiology are poorly understood. RESULTS: We identified a rare missense heterozygous VPS50 mutation (p. Gly169Val) in NTDs by high-throughput sequencing. In vitro functional analysis demonstrated that the p. Gly169Val was a loss-of-function mutation, delaying transferrin recycling and altering its interaction with VPS53. Using WISH during zebrafish embryogenesis, we demonstrated that vps50 gene was expressed throughout the early embryo, especially in the head. Abnormal body axis phenotypes were observed in those vps50 knock-down zebrafishes. Further rescue study in zebrafish suggested that the mutation displayed loss-of-function effects comparing with wild-type VPS50. CONCLUSIONS: These findings thus demonstrated that the functional mutations in VPS50 might contribute to neurodevelopmental disorder and highlighted the critical importance of VPS50 function in cellular and organismal physiology.

Novel mutations of AXIN2 identified in a Chinese Congenital Heart Disease Cohort.

Congenital heart defects (CHDs), the most common congenital human birth anomalies, involves complex genetic factors. Wnt/ß-catenin pathway is critical for cardiogenesis and proved to be associated with numerous congenital heart abnormities. AXIN2 has a unique role in Wnt/ß-catenin pathway, as it is not only an important inhibitor but also a direct target of Wnt/ß-catenin pathway. However, whether AXIN2 is associated with human CHDs has not been reported. In our present study, we found a differential expression of Axin2 mRNA during the development of mouse heart, indicating its importance in mouse cardiac development. Then using targeted next-generation sequencing, we found two novel case-specific rare mutations [c.28 C > T (p.L10F), c.395 A > G (p.K132R)] in the sequencing region of AXIN2. In vitro functional analysis suggested that L10F might be a loss-of-function mutation and K132R is a gain-of-function mutation. Both mutations disrupted Wnt/ß-catenin pathway and failed to rescue CHD phenotype caused by Axin2 knockdown in zebrafish model. Collectively, our study indicates that rare mutations in AXIN2 might contribute to the risk of human CHDs and a balanced canonical Wnt pathway is critical for cardiac development process. To our knowledge, it is the first study of AXIN2 mutations associated with human CHDs, providing new insights into CHD etiology.