Deficiency in Prader-Willi syndrome gene necdin leads to attenuated cardiac contractility.

Prader-Willi syndrome (PWS) is a genetic disorder characterized by behavioral disturbances, hyperphagia, and intellectual disability. Several surveys indicate that PWS is also associated with cardiac abnormalities, possibly contributing to a high incidence of sudden death. However, the pathological mechanisms underlying cardiac dysfunction in PWS remain unclear. In this study, we found that deficiency in necdin, an intronless gene within PWS region, led to heart systolic and diastolic dysfunction in mice. Through yeast two-hybrid screening, we identified an interaction between necdin and non-muscle myosin regulatory light chain 12a/b (MYL12 A/B). We further showed that necdin stabilized MYL12 A/B via SGT1-heat shock protein 90 (HSP90) chaperone machinery. The zebrafish lacking the MYL12 A/B analog, MYL12.1, exhibited impaired heart function, while cardiac-specific overexpression of MYL12A normalized the heart dysfunction in necdin-deficient mice. Our findings revealed necdin dysfunction as a contributing factor to cardiomyopathy in PWS patients and emphasized the importance of HSP90 chaperone machinery and non-muscle myosin in heart fitness.

Mutations in CLCN6 as a Novel Genetic Cause of Neuronal Ceroid Lipofuscinosis.

OBJECTIVE: The aim of this study was to explore the pathogenesis of CLCN6-related disease and to assess whether its Cl-/H+-exchange activity is crucial for the biological role of ClC-6. METHODS: We performed whole-exome sequencing on a girl with development delay, intractable epilepsy, behavioral abnormities, retinal dysfunction, progressive brain atrophy, suggestive of neuronal ceroid lipofuscinoses (NCLs). We generated and analyzed the first knock-in mouse model of a patient variant (p.E200A) and compared it with a Clcn6-/- mouse model. Additional functional tests were performed with heterologous expression of mutant ClC-6. RESULTS: We identified a de novo heterozygous p.E200A variant in the proband. Expression of disease-causing ClC-6E200A or ClC-6Y553C mutants blocked autophagic flux and activated transcription factors EB (TFEB) and E3 (TFE3), leading to autophagic vesicle and cholesterol accumulation. Such alterations were absent with a transport-deficient ClC-6E267A mutant. Clcn6E200A/+ mice developed severe neurodegeneration with typical features of NCLs. Mutant ClC-6E200A, but not loss of ClC-6 in Clcn6-/- mice, increased lysosomal biogenesis by suppressing mTORC1-TFEB signaling, blocked autophagic flux through impairing lysosomal function, and increased apoptosis. Carbohydrate and lipid deposits accumulated in Clcn6E200A/+ brain, while only lipid storage was found in Clcn6-/- brain. Lysosome dysfunction, autophagy defects, and gliosis were early pathogenic events preceding neuron loss. INTERPRETATION: CLCN6 is a novel genetic cause of NCLs, highlighting the importance of considering CLCN6 mutations in the diagnostic workup for molecularly undefined forms of NCLs. Uncoupling of Cl- transport from H+ countertransport in the E200A mutant has a dominant effect on the autophagic/lysosomal pathway. ANN NEUROL 2024.

PCDH17 restricts dendritic spine morphogenesis by regulating ROCK2-dependent control of the actin cytoskeleton, modulating emotional behavior.

Proper regulation of synapse formation and elimination is critical for establishing mature neuronal circuits and maintaining brain function. Synaptic abnormalities, such as defects in the density and morphology of postsynaptic dendritic spines, underlie the pathology of various neuropsychiatric disorders. Protocadherin 17 (PCDH17) is associated with major mood disorders, including bipolar disorder and depression. However, the molecular mechanisms by which PCDH17 regulates spine number, morphology, and behavior remain elusive. In this study, we found that PCDH17 functions at postsynaptic sites, restricting the number and size of dendritic spines in excitatory neurons. Selective overexpression of PCDH17 in the ventral hippocampal CA1 results in spine loss and anxiety- and depression-like behaviors in mice. Mechanistically, PCDH17 interacts with actin-relevant proteins and regulates actin filament (F-actin) organization. Specifically, PCDH17 binds to ROCK2, increasing its expression and subsequently enhancing the activity of downstream targets such as LIMK1 and the phosphorylation of cofilin serine-3 (Ser3). Inhibition of ROCK2 activity with belumosudil (KD025) ameliorates the defective F-actin organization and spine structure induced by PCDH17 overexpression, suggesting that ROCK2 mediates the effects of PCDH17 on F-actin content and spine development. Hence, these findings reveal a novel mechanism by which PCDH17 regulates synapse development and behavior, providing pathological insights into the neurobiological basis of mood disorders.

Targeting BMAL1 reverses drug resistance of acute myeloid leukemia cells and promotes ferroptosis through HMGB1-GPX4 signaling pathway.

PURPOSE: Acute myeloid leukemia (AML) is a refractory hematologic malignancy that poses a serious threat to human health. Exploring alternative therapeutic strategies capable of inducing alternative modes of cell death, such as ferroptosis, holds great promise as a viable and effective intervention. METHODS: We analyzed online database data and collected clinical samples to verify the expression and function of BMAL1 in AML. We conducted experiments on AML cell proliferation, cell cycle, ferroptosis, and chemotherapy resistance by overexpressing/knocking down BMAL1 and using assays such as MDA detection and BODIPY 581/591 C11 staining. We validated the transcriptional regulation of HMGB1 by BMAL1 through ChIP assay, luciferase assay, RNA level detection, and western blotting. Finally, we confirmed the results of our cell experiments at the animal level. RESULTS: BMAL1 up-regulation is an observed phenomenon in AML patients. Furthermore, there existed a strong correlation between elevated levels of BMAL1 expression and inferior prognosis in individuals with AML. We found that knocking down BMAL1 inhibited AML cell growth by blocking the cell cycle. Conversely, overexpressing BMAL1 promoted AML cell proliferation. Moreover, our research results revealed that BMAL1 inhibited ferroptosis in AML cells through BMAL1-HMGB1-GPX4 pathway. Finally, knocking down BMAL1 can enhance the efficacy of certain first-line cancer therapeutic drugs, including venetoclax, dasatinib, and sorafenib. CONCLUSION: Our research results suggest that BMAL1 plays a crucial regulatory role in AML cell proliferation, drug resistance, and ferroptosis. BMAL1 could be a potential important therapeutic target for AML.

KCTD10 regulates brain development by destabilizing brain disorder-associated protein KCTD13.

KCTD10 belongs to the KCTD (potassiumchannel tetramerization domain) family, many members of which are associated with neuropsychiatric disorders. However, the biological function underlying the association with brain disorders remains to be explored. Here, we reveal that Kctd10 is highly expressed in neuronal progenitors and layer V neurons throughout brain development. Kctd10 deficiency triggers abnormal proliferation and differentiation of neuronal progenitors, reduced deep-layer (especially layer V) neurons, increased upper-layer neurons, and lowered brain size. Mechanistically, we screened and identified a unique KCTD10-interacting protein, KCTD13, associated with neurodevelopmental disorders. KCTD10 mediated the ubiquitination-dependent degradation of KCTD13 and KCTD10 ablation resulted in a considerable increase of KCTD13 expression in the developing cortex. KCTD13 overexpression in neuronal progenitors led to reduced proliferation and abnormal cell distribution, mirroring KCTD10 deficiency. Notably, mice with brain-specific Kctd10 knockout exhibited obvious motor deficits. This study uncovers the physiological function of KCTD10 and provides unique insights into the pathogenesis of neurodevelopmental disorders.

Application of Machine Learning to Ultrasonography in Identifying Anatomical Landmarks for Cricothyroidotomy Among Female Adults: A Multi-center Prospective Observational Study.

We aimed to develop machine learning (ML)-based algorithms to assist physicians in ultrasound-guided localization of cricoid cartilage (CC) and thyroid cartilage (TC) in cricothyroidotomy. Adult female volunteers were prospectively recruited from two hospitals between September and December, 2020. Ultrasonographic images were collected via a modified longitudinal technique. You Only Look Once (YOLOv5s), Faster Regions with Convolutional Neural Network features (Faster R-CNN), and Single Shot Detector (SSD) were selected as the model architectures. A total of 488 women (mean age: 36.0 years) participated in the study, contributing to a total of 292,053 frames of ultrasonographic images. The derived ML-based algorithms demonstrated excellent discriminative performance for the presence of CC (area under the receiver operating characteristic curve [AUC]: YOLOv5s, 0.989, 95% confidence interval [CI]: 0.982-0.994; Faster R-CNN, 0.986, 95% CI: 0.980-0.991; SSD, 0.968, 95% CI: 0.956-0.977) and TC (AUC: YOLOv5s, 0.989, 95% CI: 0.977-0.997; Faster R-CNN, 0.981, 95% CI: 0.965-0.991; SSD, 0.982, 95% CI: 0.973-0.990). Furthermore, in the frames where the model could correctly indicate the presence of CC or TC, it also accurately localized CC (intersection-over-union: YOLOv5s, 0.753, 95% CI: 0.739-0.765; Faster R-CNN, 0.720, 95% CI: 0.709-0.732; SSD, 0.739, 95% CI: 0.726-0.751) or TC (intersection-over-union: YOLOv5s, 0.739, 95% CI: 0.722-0.755; Faster R-CNN, 0.709, 95% CI: 0.687-0.730; SSD, 0.713, 95% CI: 0.695-0.730). The ML-based algorithms could identify anatomical landmarks for cricothyroidotomy in adult females with favorable discriminative and localization performance. Further studies are warranted to transfer this algorithm to hand-held portable ultrasound devices for clinical use.

Contactin-associated protein-like 2 (CNTNAP2) mutations impair the essential α-secretase cleavages, leading to autism-like phenotypes.

Mutations in the Contactin-associated protein-like 2 (CNTNAP2) gene are associated with autism spectrum disorder (ASD), and ectodomain shedding of the CNTNAP2 protein plays a role in its function. However, key enzymes involved in the C-terminal cleavage of CNTNAP2 remain largely unknown, and the effect of ASD-associated mutations on this process and its role in ASD pathogenesis remain elusive. In this report we showed that CNTNAP2 undergoes sequential cleavages by furin, ADAM10/17-dependent α-secretase and presenilin-dependent γ-secretase. We identified that the cleavage sites of ADAM10 and ADAM17 in CNTNAP2 locate at its C-terminal residue I79 and L96, and the main α-cleavage product C79 by ADAM10 is required for the subsequent γ-secretase cleavage to generate CNTNAP2 intracellular domain (CICD). ASD-associated CNTNAP2 mutations impair the α-cleavage to generate C79, and the inhibition leads to ASD-like repetitive and social behavior abnormalities in the Cntnap2-I1254T knock-in mice. Finally, exogenous expression of C79 improves autism-like phenotypes in the Cntnap2-I1254T knock-in and Cntnap2-/- knockout mice. This data demonstrates that the α-secretase is essential for CNTNAP2 processing and its function. Our study indicates that inhibition of the cleavage by pathogenic mutations underlies ASD pathogenesis, and upregulation of its C-terminal fragments could have therapeutical potentials for ASD treatment.

A genome-wide CRISPR screen identifies USP1 as a novel regulator of the mammalian circadian clock.

The circadian clock is generated by a molecular timekeeping mechanism coordinating daily oscillations of physiology and behaviors in mammals. In the mammalian circadian clockwork, basic helix-loop-helix ARNT-like protein 1 (BMAL1) is a core circadian component whose defects lead to circadian disruption and elicit behavioral arrhythmicity. To identify previously unknown regulators for circadian clocks, we searched for genes influencing BMAL1 protein level by using a CRISPR/Cas9-based genome-wide knockout library. As a result, we found that the deubiquitinase ubiquitin carboxyl-terminal hydrolase 1 (USP1) positively affects BMAL1 protein abundance. Overexpression of wild-type USP1, but not a deubiquitinase-inactive mutant USP1, upregulated BMAL1 protein level, whereas genetic ablation of USP1 downregulated BMAL1 protein level in U2OS cells. Furthermore, treatment with USP1 inhibitors led to significant downregulation of BMAL1 protein in U2OS cells as well as mouse tissues. Subsequently, genetic ablation or pharmacological inhibition of USP1 resulted in reduced mRNA levels of a panel of clock genes and disrupted circadian rhythms in U2OS cells. Mechanistically, USP1 was able to de-ubiquitinate BMAL1 and inhibit the proteasomal degradation of BMAL1. Interestingly, the expression of Usp1 was much higher than the other two deubiquitinases of BMAL1 (Usp2 and Usp9X) in the mouse heart, implying a tissue-specific function of USP1 in the regulation of BMAL1 stability. Our work thus identifies deubiquitinase USP1 as a previously unknown regulator of the mammalian circadian clock and highlights the potential of genome-wide CRISPR screens in the identification of regulators for the circadian clock.

Cry1Δ11 mutation induces ADHD-like symptoms through hyperactive dopamine D1 receptor signaling.

Attention-deficit hyperactivity disorder (ADHD) is a highly heritable neurodevelopmental disorder that affects approximately 5.3% of children and approximately 2.5% of adults. There is an intimate relationship between ADHD and sleep disturbance. Specifically, individuals carry a mutation in the core circadian gene CRY1 (c. 1657 + 3A > C), which results in the deletion of exon 11 expression in the CRY1 protein (CRY1Δ11), causing them to exhibit typical ADHD symptoms. However, the underlying mechanism is still elusive. In this study, we demonstrate that Cry1Δ11 (c. 1717 + 3A > C) mice showed ADHD-like symptoms, including hyperactivity, impulsivity, and deficits in learning and memory. A hyperactive cAMP signaling pathway was found in the nucleus accumbens (NAc) of Cry1Δ11 mice. We further demonstrated that upregulated c-Fos was mainly localized in dopamine D1 receptor-expressing medium spiny neurons (DRD1-MSNs) in the NAc. Neuronal excitability of DRD1-MSNs in the NAc of Cry1Δ11 mice was significantly higher than that of WT controls. Mechanistically, the CRY1Δ11 protein, in contrast to the WT CRY1 protein, failed to interact with the Gαs protein and inhibit DRD1 signaling. Finally, the DRD1 antagonist SCH23390 normalized most ADHD-like symptoms in Cry1Δ11 mice. Thus, our results reveal hyperactive DRD1 signaling as an underlying mechanism and therapeutic target for ADHD induced by the highly prevalent CRY1Δ11 mutation.

CNTNAP2 intracellular domain (CICD) generated by γ-secretase cleavage improves autism-related behaviors.

As the most prevalent neurodevelopmental disorders in children, autism spectrum disorders (ASD) are characterized by deficits in language development, social interaction, and repetitive behaviors or inflexible interests. Contactin associated protein like 2 (CNTNAP2), encoding a single transmembrane protein (CNTNAP2) with 1331 amino acid residues, is a widely validated ASD-susceptible gene. Cntnap2-deficient mice also show core autism-relevant behaviors, including the social deficits and repetitive behavior. However, the cellular mechanisms underlying dysfunction CNTNAP2 and ASD remain elusive. In this study, we found a motif within the transmembrane domain of CNTNAP2 was highly homologous to the γ-secretase cleavage site of amyloid-ß precursor protein (APP), suggesting that CNTNAP2 may undergo proteolytic cleavage. Further biochemical analysis indicated that CNTNAP2 is cleaved by γ-secretase to produce the CNTNAP2 intracellular domain (CICD). Virally delivery of CICD to the medial prefrontal cortex (mPFC) in Cntnap2-deficient (Cntnap2-/-) mice normalized the deficit in the ASD-related behaviors, including social deficit and repetitive behaviors. Furthermore, CICD promoted the nuclear translocation of calcium/calmodulin-dependent serine protein kinase (CASK) to regulate the transcription of genes, such as Prader Willi syndrome gene Necdin. Whereas Necdin deficiency led to reduced social interaction in mice, virally expression of Necdin in the mPFC normalized the deficit in social preference of Cntnap2-/- mice. Our results thus reveal a critical function of CICD and highlight a role of the CNTNAP2-CASK-Necdin signaling pathway in ASD.

FMRP binds Per1 mRNA and downregulates its protein expression in mice.

FMRP, an RNA-binding protein, has previously shown to be involved in regulation of circadian rhythms in flies and mice. However, the molecular mechanism remains elusive. Here we demonstrate that core circadian component Per1 mRNA was a target of FMRP and the association leads to reduced PER1 expression. In Fmr1 KO mice, the oscillation of PER1 protein expression was significantly affected in a temporal and tissue-dependent pattern when compared to WT mice. Our work thus identified Per1 mRNA as a novel target of FMRP and suggested a potential role of FMRP in regulation of circadian function.

A glucose-blue light AND gate-controlled chemi-optogenetic cell-implanted therapy for treating type-1 diabetes in mice.

Exogenous insulin therapy is the mainstay treatment for Type-1 diabetes (T1D) caused by insulin deficiency. A fine-tuned insulin supply system is important to maintain the glucose homeostasis. In this study, we present a designed cell system that produces insulin under an AND gate control, which is triggered only in the presence of both high glucose and blue light illumination. The glucose-sensitive GIP promoter induces the expression of GI-Gal4 protein, which forms a complex with LOV-VP16 in the presence of blue light. The GI-Gal4:LOV-VP16 complex then promotes the expression of UAS-promoter-driven insulin. We transfected these components into HEK293T cells, and demonstrated the insulin was secreted under the AND gate control. Furthermore, we showed the capacity of the engineered cells to improve the blood glucose homeostasis through implantation subcutaneously into Type-1 diabetes mice.

GSN gene frameshift mutations in Alzheimer's disease.

BACKGROUND: The pathogenic missense mutations of the gelsolin (GSN) gene lead to familial amyloidosis of the Finnish type (FAF); however, our previous study identified GSN frameshift mutations existed in patients with Alzheimer's disease (AD). The GSN genotype-phenotype heterogeneity and the role of GSN frameshift mutations in patients with AD are unclear. METHOD: In total, 1192 patients with AD and 1403 controls were screened through whole genome sequencing, and 884 patients with AD were enrolled for validation. Effects of GSN mutations were evaluated in vitro. GSN, Aß42, Aß40 and Aß42/40 were detected in both plasma and cerebrospinal fluid (CSF). RESULTS: Six patients with AD with GSN P3fs and K346fs mutations (0.50%, 6/1192) were identified, who were diagnosed with AD but not FAF. In addition, 13 patients with AD with GSN frameshift mutations were found in the validation cohort (1.47%, 13/884). Further in vitro experiments showed that both K346fs and P3fs mutations led to the GSN loss of function in inhibiting Aß-induced toxicity. Moreover, a higher level of plasma (p=0.001) and CSF (p=0.005) GSN was observed in AD cases than controls, and a positive correlation was found between the CSF GSN and CSF Aß42 (r=0.289, p=0.009). Besides, the GSN level was initially increasing and then decreasing with the disease course and cognitive decline. CONCLUSIONS: GSN frameshift mutations may be associated with AD. An increase in plasma GSN is probably a compensatory reaction in AD, which is a potential biomarker for early AD.

A functional spectrum of PROKR2 mutations identified in isolated hypogonadotropic hypogonadism.

Isolated hypogonadotropic hypogonadism (IHH) is a rare disease with hypogonadism and infertility caused by the defects in embryonic migration of hypothalamic gonadotropin-releasing hormone (GnRH) neurons, hypothalamic GnRH secretion or GnRH signal transduction. PROKR2 gene, encoding a G-protein coupled receptor PROKR2, is one of the most frequently mutated genes identified in IHH patients. However, the functional consequences of several PROKR2 mutants remain elusive. In this study, we systematically analyzed the Gαq, Gαs and ERK1/2 signaling of 23 IHH-associated PROKR2 mutations which are yet to be functionally characterized. We demonstrate that blockage of Gαq, instead of MAPK/ERK pathway, inhibited PROK2-induced migration of PROKR2-expressing cells, implying that PROKR2-related IHH results primarily due to Gαq signaling pathway disruption. Combined with previous reports, we categorized a total of 63 IHH-associated PROKR2 mutations into four distinct groups according Gαq pathway functionality: (i) neutral (N, >80% activity); (ii) low pathogenicity (L, 50-80% activity); (iii) medium pathogenicity (M, 20-50% activity) and (iv) high pathogenicity (H, <20% activity). We further compared the cell-based functional results with in silico mutational prediction programs. Our results indicated that while Sorting Intolerant from Tolerant predictions were accurate for transmembrane region mutations, mutations localized in the intracellular and extracellular domains were accurately predicted by the Combined Annotation Dependent Depletion prediction tool. Our results thus provide a functional database that can be used to guide diagnosis and appropriate genetic counseling in IHH patients with PROKR2 mutations.

TRIM28 secures skeletal stem cell fate during skeletogenesis by silencing neural gene expression and repressing GREM1/AKT/mTOR signaling axis.

Long bones are generated by mesoderm-derived skeletal progenitor/stem cells (SSCs) through endochondral ossification, a process of sequential chondrogenic and osteogenic differentiation tightly controlled by the synergy between intrinsic and microenvironment cues. Here, we report that loss of TRIM28, a transcriptional corepressor, in mesoderm-derived cells expands the SSC pool, weakens SSC osteochondrogenic potential, and endows SSCs with properties of ectoderm-derived neural crest cells (NCCs), leading to severe defects of skeletogenesis. TRIM28 preferentially enhances H3K9 trimethylation and DNA methylation on chromatin regions more accessible in NCCs; loss of this silencing upregulates neural gene expression and enhances neurogenic potential. Moreover, TRIM28 loss causes hyperexpression of GREM1, which is an extracellular signaling factor promoting SSC self-renewal and SSC neurogenic potential by activating AKT/mTORC1 signaling. Our results suggest that TRIM28-mediated chromatin silencing establishes a barrier for maintaining the SSC lineage trajectory and preventing a transition to ectodermal fate by regulating both intrinsic and microenvironment cues.

A non-coding variant in 5' untranslated region drove up-regulation of pseudo-kinase EPHA10 and caused non-syndromic hearing loss in humans.

Hereditary hearing loss has a genetic and phenotypic heterogeneity. However, it is still difficult to explain this heterogeneity perfectly with known deafness genes. Here, we report a novel causative gene EPHA10 as well as its non-coding variant in 5' untranslated region identified in a family with post-lingual autosomal dominant non-syndromic hearing loss from southern China. One affected member of this family had an ideal hearing restoration after cochlear implantation. We speculated that there were probable deafness-causing abnormalities in the cochlea according to clinical imaging and auditory evaluations. A heterozygous variant c.-81_-73delinsAGC was found co-segregating with hearing loss. Epha10 was expressed in mouse cochlea at both transcription and translation levels. The variant caused upregulation of EPHA10 which may result from promoter activity enhancement after sequence change. Overexpression of Eph (the homolog of human EPHA10) exerted effects on the structure and function of chordotonal organ in fly model. In summary, our study linked pseudo-kinase EPHA10 to hearing loss in humans for the first time.

Expression of expanded GGC repeats within NOTCH2NLC causes behavioral deficits and neurodegeneration in a mouse model of neuronal intranuclear inclusion disease.

GGC repeat expansions within NOTCH2NLC have been identified as the genetic cause of neuronal intranuclear inclusion disease (NIID). To understand the molecular pathogenesis of NIID, here, we established both a transgenic mouse model and a human neural progenitor cells (hNPCs) model. Expression of the NOTCH2NLC with expanded GGC repeats produced widespread intranuclear and perinuclear polyglycine (polyG), polyalanine (polyA), and polyarginine (polyR) inclusions, leading to behavioral deficits and severe neurodegeneration, which faithfully mimicked the clinical and pathological features associated with NIID. Furthermore, conserved alternative splicing events were identified between the NIID mouse and hNPC models, among which was the enrichment of the binding motifs of hnRNPM, an RNA binding protein known as alternative splicing regulator. Expanded NOTCH2NLC-polyG and NOTCH2NLC-polyA could interact with and sequester hnRNPM, while overexpression of hnRNPM could ameliorate the cellular toxicity. These results together suggested that dysfunction of hnRNPM could play an important role in the molecular pathogenesis of NIID.

UBR5 Acts as an Antiviral Host Factor against MERS-CoV via Promoting Ubiquitination and Degradation of ORF4b.

Within the past 2 decades, three highly pathogenic human coronaviruses have emerged, namely, severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The health threats and economic burden posed by these tremendously severe coronaviruses have paved the way for research on their etiology, pathogenesis, and treatment. Compared to SARS-CoV and SARS-CoV-2, MERS-CoV genome encoded fewer accessory proteins, among which the ORF4b protein had anti-immunity ability in both the cytoplasm and nucleus. Our work for the first time revealed that ORF4b protein was unstable in the host cells and could be degraded by the ubiquitin proteasome system. After extensive screenings, it was found that UBR5 (ubiquitin protein ligase E3 component N-recognin 5), a member of the HECT E3 ubiquitin ligases, specifically regulated the ubiquitination and degradation of ORF4b. Similar to ORF4b, UBR5 can also translocate into the nucleus through its nuclear localization signal, enabling it to regulate ORF4b stability in both the cytoplasm and nucleus. Through further experiments, lysine 36 was identified as the ubiquitination site on the ORF4b protein, and this residue was highly conserved in various MERS-CoV strains isolated from different regions. When UBR5 was knocked down, the ability of ORF4b to suppress innate immunity was enhanced and MERS-CoV replication was stronger. As an anti-MERS-CoV host protein, UBR5 targets and degrades ORF4b protein through the ubiquitin proteasome system, thereby attenuating the anti-immunity ability of ORF4b and ultimately inhibiting MERS-CoV immune escape, which is a novel antagonistic mechanism of the host against MERS-CoV infection. IMPORTANCE ORF4b was an accessory protein unique to MERS-CoV and was not present in SARS-CoV and SARS-CoV-2 which can also cause severe respiratory disease. Moreover, ORF4b inhibited the production of antiviral cytokines in both the cytoplasm and the nucleus, which was likely to be associated with the high lethality of MERS-CoV. However, whether the host proteins regulate the function of ORF4b is unknown. Our study first determined that UBR5, a host E3 ligase, was a potential host anti-MERS-CoV protein that could reduce the protein level of ORF4b and diminish its anti-immunity ability by inducing ubiquitination and degradation. Based on the discovery of ORF4b-UBR5, a critical molecular target, further increasing the degradation of ORF4b caused by UBR5 could provide a new strategy for the clinical development of drugs for MERS-CoV.

ANOS1 variants in a large cohort of Chinese patients with congenital hypogonadotropic hypogonadism. / ä¸­å›½å ˆå¤©æ€§ä½Žä¿ƒæ€§è ºæ¿€ç´ æ€§æ€§è ºåŠŸèƒ½å‡é€€ç—‡æ‚£è€ ANOS1的突变.

OBJECTIVES: Congenital hypogonadotropic hypogonadism (CHH) is a rare congenital gonadal dysplasia caused by defects in the synthesis, secretion or signal transduction of hypothalamic gonadotropin releasing hormone. The main manifestations of CHH are delayed or lack puberty, low levels of sex hormones and gonadotropins, and may be accompanied with other clinical phenotypes. Some patients with CHH are also accompanied with anosmia or hyposmia, which is called Kalman syndrome (KS). ANOS1, located on X chromosome, is the first gene associated with CHH in an X-linked recessive manner. This study aims to provide a basis for the genetic diagnosis of CHH by analyzing the gene variant spectrum of ANOS1 in CHH and the relationship between clinical phenotype and genotype. METHODS: In this study, whole exome sequencing (WES) was used to screen rare sequencing variants (RSVs) of ANOS1 in a Chinese cohort of 165 male CHH patients. Four commonly used in silico tools were used to predict the function of the identified RSVs in coding region, including Polyphen2, Mutation Taster, SIFT, and Combined Annotation Dependent Depletion (CADD). Splice Site Prediction by Neural Network (NNSPLICE) was employed to predict possibilities of intronic RSVs to disrupt splicing. American College of Medical Genetics and Genomics (ACMG) guidelines was used to assess the pathogenicity of the detected RSVs. The ANOS1 genetic variant spectrum of CHH patients in Chinese population was established. The relationship between clinical phenotype and genotype was analyzed by collecting detailed clinical data. RESULTS: Through WES analysis for 165 CHH patients, ANOS1 RSVs were detected in 17 of them, with the frequency of 10.3%. A total of 13 RSVs were detected in the 17 probands, including 5 nonsense variants (p.T76X, p.R191X, p.W257X, p.R262X, and p.W589X), 2 splicing site variants (c.318+3A>C, c.1063-1G>C), and 6 missense variants (p.N402S, p.N155D, p.P504L, p.C157R, p.Q635P, and p.V560I). In these 17 CHH probands with ANOS1 RSVs, many were accompanied with other clinical phenotypes. The most common associated phenotype was cryptorchidism (10/17), followed by unilateral renal agenesis (3/17), dental agenesis (3/17), and synkinesia (3/17). Eight RSVs, including p.T76X, p.R191X, p.W257X, p.R262X, p.W589X, c.318+3A>C, c.1063-1G>C, and p.C157R, were predicted to be pathogenic or likely pathogenic ANOS1 RSVs by ACMG. Eight CHH patients with pathogenic or likely pathogenic ANOS1 variants had additional features. In contrast, only one out of nine CHH patients with non-pathogenic (likely benign or uncertain of significance) ANOS1 variants according to ACMG exhibited additional features. And function of the non-pathogenic ANOS1 variants accompanied with other CHH-associated RSVs. CONCLUSIONS: The ANOS1 genetic spectrum of CHH patients in Chinese population is established. Some of the correlations between clinical phenotype and genotype are also established. Our study indicates that CHH patients with pathogenic or likely pathogenic ANOS1 RSVs tend to exhibit additional phenotypes. Although non-pathogenic ANOS1 variants only may not be sufficient to cause CHH, they may function together with other CHH-associated RSVs to cause the disease.

[Analysis of PROKR2 gene mutation in patients with hypogonadotropic hypogonadism].

To investigate the clinical and genetic characteristics of patients with idiopathic hypogonadotropic hypogonadism (IHH), the clinical data of 23 patients with IHH were retrospectively analyzed. Gene analyses were accomplished with whole-exome sequencing (WES) and Sanger sequencing. Functional prediction of mutation sites was conducted using two bioinformatics platforms, SIFT and Polyphen. Among the 23 patients with IHH, 9 patients carried prokinin 2 (PROKR2) gene mutations including 4 missense mutations (p.W178S, p.Y113H, p.A103V, p.R164Q), and 1 frameshift mutation (p.D42delinsDED), the remaining 14 cases were found negative in gene sequencing. Functional prediction showed that the above mutations may affect protein function suggestive of a pathogenic role of PROKR2 mutation in the patients. There were no significant differences in the levels of follicle-stimulating hormone, luteinizing hormone, testosterone, and estradiol between the IHH patients with PROKR2 gene mutation and those without. PROKR2 gene mutation might associated with IHH, and the mutations reported in the present study could enrich the pathogenic spectrum of genes.