scholarly journals Bi-allelic variants in TSPOAP1, encoding the active zone protein RIMBP1, cause autosomal recessive dystonia

2020 ◽  
Author(s):  
Niccolò E. Mencacci ◽  
Marisa M. Brockmann ◽  
Jinye Dai ◽  
Sander Pajusalu ◽  
Burcu Atasu ◽  
...  
Keyword(s):  
Active Zone ◽  
Autosomal Recessive ◽  
Critical Role ◽  
Cerebellar Atrophy ◽  
Missense Variant ◽  
Loss Of Function ◽  
Generalized Dystonia ◽  
Motor Abnormalities ◽  
Vitro Analysis

ABSTRACTDystonia is a debilitating hyperkinetic movement disorder, frequently transmitted as a monogenic trait. Here, we describe homozygous frameshift, nonsense and missense variants in TSPOAP1, encoding the active zone RIM-binding protein 1 (RIMBP1), as a novel genetic cause of autosomal recessive dystonia in seven subjects from three unrelated families. Subjects carrying loss-of-function variants presented with juvenile- onset progressive generalized dystonia, associated with intellectual disability and cerebellar atrophy. Conversely, subjects carrying a pathogenic missense variant (p.Gly1808Ser) presented with isolated adult-onset focal dystonia. In mice, complete loss of RIMBP1, known to reduce neurotransmission, led to motor abnormalities reminiscent of dystonia, decreased Purkinje cell dendritic arborization, and reduced numbers of cerebellar synapses. In vitro analysis of the p.Gly1808Ser variant showed larger spike-evoked calcium transients and enhanced neurotransmission, suggesting that RIMBP1-linked dystonia can be caused by either reduced or enhanced rates of spike-evoked release in relevant neural networks. Our findings establish a direct link between presynaptic RIMBP1 dysfunction and dystonia and highlight the critical role played by well-balanced neurotransmission in motor control and disease pathogenesis.

scholarly journals DJ-1 regulates the integrity and function of ER-mitochondria association through interaction with IP3R3-Grp75-VDAC1

2019 ◽  
Vol 116 (50) ◽  
pp. 25322-25328 ◽  
Author(s):  
Yi Liu ◽  
Xiaopin Ma ◽  
Hisashi Fujioka ◽  
Jun Liu ◽  
Shengdi Chen ◽  
...  
Keyword(s):  
Autosomal Recessive ◽  
Cellular Mechanism ◽  
Loss Of Function ◽  
Wild Type ◽  
Calcium Efflux ◽  
And Function ◽  
The Brain ◽  
Early Onset Parkinson’S Disease

Loss-of-function mutations in DJ-1 are associated with autosomal recessive early onset Parkinson’s disease (PD), yet the underlying pathogenic mechanism remains elusive. Here we demonstrate that DJ-1 localized to the mitochondria-associated membrane (MAM) both in vitro and in vivo. In fact, DJ-1 physically interacts with and is an essential component of the IP3R3-Grp75-VDAC1 complexes at MAM. Loss of DJ-1 disrupted the IP3R3-Grp75-VDAC1 complex and led to reduced endoplasmic reticulum (ER)-mitochondria association and disturbed function of MAM and mitochondria in vitro. These deficits could be rescued by wild-type DJ-1 but not by the familial PD-associated L166P mutant which had demonstrated reduced interaction with IP3R3-Grp75. Furthermore, DJ-1 ablation disturbed calcium efflux-induced IP3R3 degradation after carbachol treatment and caused IP3R3 accumulation at the MAM in vitro. Importantly, similar deficits in IP3R3-Grp75-VDAC1 complexes and MAM were found in the brain of DJ-1 knockout mice in vivo. The DJ-1 level was reduced in the substantia nigra of sporadic PD patients, which was associated with reduced IP3R3-DJ-1 interaction and ER-mitochondria association. Together, these findings offer insights into the cellular mechanism in the involvement of DJ-1 in the regulation of the integrity and calcium cross-talk between ER and mitochondria and suggests that impaired ER-mitochondria association could contribute to the pathogenesis of PD.

scholarly journals A combined in silico, in vitro and clinical approach to characterise novel pathogenic missense variants in PRPF31 in retinitis pigmentosa

2018 ◽  
Author(s):  
Gabrielle Wheway ◽  
Liliya Nazlamova ◽  
Nervine Meshad ◽  
Samantha Hunt ◽  
Nicola Jackson ◽  
...  
Keyword(s):  
Retinitis Pigmentosa ◽  
In Silico ◽  
Autosomal Dominant ◽  
Missense Variant ◽  
Incomplete Penetrance ◽  
Clinical Approach ◽  
Loss Of Function ◽  
Autosomal Dominant Retinitis Pigmentosa ◽  
Missense Variants

AbstractAt least six different proteins of the spliceosome, including PRPF3, PRPF4, PRPF6, PRPF8, PRPF31 and SNRNP200, are mutated in autosomal dominant retinitis pigmentosa (adRP). These proteins have recently been shown to localise to the base of the connecting cilium of the retinal photoreceptor cells, elucidating this form of RP as a retinal ciliopathy. In the case of loss-of-function variants in these genes, pathogenicity can easily be ascribed. In the case of missense variants, this is more challenging. Furthermore, the exact molecular mechanism of disease in this form of RP remains poorly understood.In this paper we take advantage of the recently published cryo EM-resolved structure of the entire human spliceosome, to predict the effect of a novel missense variant in one component of the spliceosome; PRPF31, found in a patient attending the genetics eye clinic at Bristol Eye Hospital. Monoallelic variants in PRPF31 are a common cause of autosomal dominant retinitis pigmentosa (adRP) with incomplete penetrance. We use in vitro studies to confirm pathogenicity of this novel variant PRPF31 c.341T>A, p.Ile114Asn.This work demonstrates how in silico modelling of structural effects of missense variants on cryo-EM resolved protein complexes can contribute to predicting pathogenicity of novel variants, in combination with in vitro and clinical studies. It is currently a considerable challenge to assign pathogenic status to missense variants in these proteins.

scholarly journals A hypomorphic allele of SLC35D1 results in Schneckenbecken-like dysplasia

2019 ◽  
Vol 28 (21) ◽  
pp. 3543-3551
Author(s):  
Carsten Rautengarten ◽  
Oliver W Quarrell ◽  
Karen Stals ◽  
Richard C Caswell ◽  
Elisa De Franco ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Missense Variant ◽  
Sugar Transporter ◽  
Loss Of Function ◽  
Transport Activity ◽  
Nucleotide Sugar ◽  
Gene Encoding ◽  
Hypomorphic Allele ◽  
Nucleotide Sugar Transporter

Abstract We report the case of a consanguineous couple who lost four pregnancies associated with skeletal dysplasia. Radiological examination of one fetus was inconclusive. Parental exome sequencing showed that both parents were heterozygous for a novel missense variant, p.(Pro133Leu), in the SLC35D1 gene encoding a nucleotide sugar transporter. The affected fetus was homozygous for the variant. The radiological features were reviewed, and being similar, but atypical, the phenotype was classified as a ‘Schneckenbecken-like dysplasia.’ The effect of the missense change was assessed using protein modelling techniques and indicated alterations in the mouth of the solute channel. A detailed biochemical investigation of SLC35D1 transport function and that of the missense variant p.(Pro133Leu) revealed that SLC35D1 acts as a general UDP-sugar transporter and that the p.(Pro133Leu) mutation resulted in a significant decrease in transport activity. The reduced transport activity observed for p.(Pro133Leu) was contrasted with in vitro activity for SLC35D1 p.(Thr65Pro), the loss-of-function mutation was associated with Schneckenbecken dysplasia. The functional classification of SLC35D1 as a general nucleotide sugar transporter of the endoplasmic reticulum suggests an expanded role for this transporter beyond chondroitin sulfate biosynthesis to a variety of important glycosylation reactions occurring in the endoplasmic reticulum.

scholarly journals SOX2 Plays a Critical Role in the Pituitary, Forebrain, and Eye during Human Embryonic Development

2008 ◽  
Vol 93 (5) ◽  
pp. 1865-1873 ◽  
Author(s):  
Daniel Kelberman ◽  
Sandra C. P. de Castro ◽  
Shuwen Huang ◽  
John A. Crolla ◽  
Rodger Palmer ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Anterior Pituitary ◽  
De Novo ◽  
Hypogonadotropic Hypogonadism ◽  
Expression Patterns ◽  
Critical Role ◽  
Loss Of Function ◽  
De Novo Mutations ◽  
Direct Role

Abstract Context: Heterozygous, de novo mutations in the transcription factor SOX2 are associated with bilateral anophthalmia or severe microphthalmia and hypopituitarism. Variable additional abnormalities include defects of the corpus callosum and hippocampus. Objective: We have ascertained a further three patients with severe eye defects and pituitary abnormalities who were screened for mutations in SOX2. To provide further evidence of a direct role for SOX2 in hypothalamo-pituitary development, we have studied the expression of the gene in human embryonic tissues. Results: All three patients harbored heterozygous SOX2 mutations: a deletion encompassing the entire gene, an intragenic deletion (c.70_89del), and a novel nonsense mutation (p.Q61X) within the DNA binding domain that results in impaired transactivation. We also show that human SOX2 can inhibit β-catenin-driven reporter gene expression in vitro, whereas mutant SOX2 proteins are unable to repress efficiently this activity. Furthermore, we show that SOX2 is expressed throughout the human brain, including the developing hypothalamus, as well as Rathke’s pouch, the developing anterior pituitary, and the eye. Conclusions: Patients with SOX2 mutations often manifest the unusual phenotype of hypogonadotropic hypogonadism, with sparing of other pituitary hormones despite anterior pituitary hypoplasia. SOX2 expression patterns in human embryonic development support a direct involvement of the protein during development of tissues affected in these individuals. Given the critical role of Wnt-signaling in the development of most of these tissues, our data suggest that a failure to repress the Wnt-β-catenin pathway could be one of the underlying pathogenic mechanisms associated with loss-of-function mutations in SOX2.

scholarly journals P-selectin glycoprotein ligand regulates the interaction of multiple myeloma cells with the bone marrow microenvironment

Blood ◽  
2012 ◽  
Vol 119 (6) ◽  
pp. 1468-1478 ◽  
Author(s):  
Abdel Kareem Azab ◽  
Phong Quang ◽  
Feda Azab ◽  
Costas Pitsillides ◽  
Brian Thompson ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Drug Resistance ◽  
Stromal Cells ◽  
Critical Role ◽  
Loss Of Function ◽  
Downstream Signaling ◽  
Target Organs ◽  
Regulation Of Growth

Abstract Interactions between multiple myeloma (MM) cells and the BM microenvironment play a critical role in the pathogenesis of MM and in the development of drug resistance by MM cells. Selectins are involved in extravasation and homing of leukocytes to target organs. In the present study, we focused on adhesion dynamics that involve P-selectin glycoprotein ligand-1 (PSGL-1) on MM cells and its interaction with selectins in the BM microenvironment. We show that PSGL-1 is highly expressed on MM cells and regulates the adhesion and homing of MM cells to cells in the BM microenvironment in vitro and in vivo. This interaction involves both endothelial cells and BM stromal cells. Using loss-of-function studies and the small-molecule pan-selectin inhibitor GMI-1070, we show that PSGL-1 regulates the activation of integrins and downstream signaling. We also document that this interaction regulates MM-cell proliferation in coculture with BM microenvironmental cells and the development of drug resistance. Furthermore, inhibiting this interaction with GMI-1070 enhances the sensitization of MM cells to bortezomib in vitro and in vivo. These data highlight the critical contribution of PSGL-1 to the regulation of growth, dissemination, and drug resistance in MM in the context of the BM microenvironment.

scholarly journals Critical Role of E1623 Residue in S3-S4 Loop of Nav1.1 Channel and Correlation Between Nature of Substitution and Functional Alteration

2022 ◽  
Vol 14 ◽  
Author(s):  
Tao Su ◽  
Meng-Long Chen ◽  
Li-Hong Liu ◽  
Hen Meng ◽  
Bin Tang ◽  
...  
Keyword(s):  
Current Density ◽  
Genetic Disorders ◽  
Critical Role ◽  
Missense Variant ◽  
Loss Of Function ◽  
Channel Conductance ◽  
Peak Current Density ◽  
Functional Changes ◽  
Functional Alteration

Objective: An overwhelming majority of the genetic variants associated with genetic disorders are missense. The association between the nature of substitution and the functional alteration, which is critical in determining the pathogenicity of variants, remains largely unknown. With a novel missense variant (E1623A) identified from two epileptic cases, which occurs in the extracellular S3-S4 loop of Nav1.1, we studied functional changes of all latent mutations at residue E1623, aiming to understand the relationship between substitution nature and functional alteration.Methods: Six latent mutants with amino acid substitutions at E1623 were generated, followed by measurements of their electrophysiological alterations. Different computational analyses were used to parameterize the residue alterations.Results: Structural modeling indicated that the E1623 was located in the peripheral region far from the central pore, and contributed to the tight turn of the S3-S4 loop. The E1623 residue exhibited low functional tolerance to the substitutions with the most remarkable loss-of-function found in E1623A, including reduced current density, less steady-state availability of activation and inactivation, and slower recovery from fast inactivation. Correlation analysis between electrophysiological parameters and the parameterized physicochemical properties of different residues suggested that hydrophilicity of side-chain at E1623 might be a crucial contributor for voltage-dependent kinetics. However, none of the established algorithms on the physicochemical variations of residues could well predict changes in the channel conductance property indicated by peak current density.Significance: The results established the important role of the extracellular S3-S4 loop in Nav1.1 channel gating and proposed a possible effect of local conformational loop flexibility on channel conductance and kinetics. Site-specific knowledge of protein will be a fundamental task for future bioinformatics.

scholarly journals Knockdown of EIF3H inhibits the development and progression of pancreatic cancer by regulating cell proliferation and apoptosis in vitro

2022 ◽  
Vol 67 (4) ◽  
pp. 83-90
Author(s):  
Yuqiang Shan ◽  
Wencheng Kong ◽  
Akao Zhu ◽  
Jiangtao Li ◽  
Huicheng Jin ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Cancer Cells ◽  
Critical Role ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Loss Of Function ◽  
Eukaryotic Translation ◽  
Proliferation Capacity ◽  
Pancreatic Cancer Cells

Nowadays, pancreatic cancer has been recognized as one of the most fatal malignancies worldwide, the molecular mechanism of which is still not fully understood. In this study, we aimed to uncover the fundamental functions of the eukaryotic translation initiation factor 3H subunit (EIF3H) in the development and progression of pancreatic cancer. Firstly, the results of immunohistochemical (IHC) staining revealed that EIF3H was highly expressed in pancreatic cancer. Moreover, lentiviruses were used to deliver shRNAs into pancreatic cancer cells for silencing EIF3H. Furthermore, the loss-of-function assays demonstrated that knockdown of EIF3H could inhibit the progression of pancreatic cancer cells by reducing proliferation capacity, promoting apoptosis, arresting cell cycle in G2 and suppressing cell migration. In summary, EIF3H may play a critical role in the development and progression of pancreatic cancer, which possesses the potential to act as a therapeutic target for pancreatic cancer treatment.

scholarly journals Hypolipidaemia among patients with PMM2-CDG is associated with low circulating PCSK9 levels: a case report followed by observational and experimental studies

2019 ◽  
Vol 57 (1) ◽  
pp. 11-17 ◽  
Author(s):  
Michael Chong ◽  
Grace Yoon ◽  
Delia Susan-Resiga ◽  
Ann Chamberland ◽  
David Cheillan ◽  
...  
Keyword(s):  
Side Effects ◽  
Experimental Studies ◽  
Ldl Receptor ◽  
Cerebellar Atrophy ◽  
Density Lipoprotein ◽  
Negative Regulator ◽  
Global Developmental Delay ◽  
Loss Of Function ◽  
Pcsk9 Inhibitors

BackgroundProprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are novel therapeutics for reducing low-density lipoprotein cholesterol (LDLc). While serious side-effects have not been observed in short-term clinical trials, there remain concerns that long-term PCSK9 inhibition may cause neurocognitive side-effects.Methods and resultsAn adult male with childhood-onset global developmental delay, cerebellar atrophy and severe hypolipidaemia underwent extensive biochemical and genetic investigations. Initial testing revealed low circulating PCSK9 levels and a common loss-of-function PCSK9 polymorphism, but these findings did not fully account for severe hypolipidaemia. Whole-exome sequencing was subsequently performed and identified two pathogenic phosphomannose mutase 2 (PMM2) variants (p.Arg141His and p.Pro69Ser) known to cause PMM2-associated congenital disorder of glycosylation (PMM2-CDG). A diagnosis of PMM2-CDG was consistent with the proband’s neurological symptoms and severe hypolipidaemia. Given that PMM2-CDG is characterised by defective protein N-glycosylation and that PCSK9 is a negative regulator of LDLc, we postulated that loss of PCSK9 N-glycosylation mediates hypolipidaemia among patients with PMM2-CDG. First, in an independent cohort of patients with PMM2-CDG (N=8), we verified that circulating PCSK9 levels were significantly lower in patients than controls (p=0.0006). Second, we conducted in vitro experiments in hepatocyte-derived cells to evaluate the effects of PCSK9 N-glycosylation loss on LDL receptor (LDLR) activity. Experimental results suggest that defective PCSK9 N-glycosylation reduces the ability of circulating PCSK9 to degrade LDLR.ConclusionLife-long exposure to genetically lower PCSK9 per se is unlikely to cause neurocognitive impairment. Both observational and experimental findings suggest that hypolipidaemia in PMM2-CDG may be partially mediated by loss of PCSK9 N-glycosylation and/or its regulators.

Determinating the role of the E3 Ubiquitin Ligase Ariadne 2 in mammalian systemss

2007 ◽  
Vol 30 (4) ◽  
pp. 87
Author(s):  
A. E. Lin ◽  
A. Wakeham ◽  
A. You-Ten ◽  
G. Wood ◽  
T. W. Mak
Keyword(s):  
Function Analysis ◽  
Critical Role ◽  
Ring Finger ◽  
E3 Ligase ◽  
Signalling Pathways ◽  
Loss Of Function ◽  
In Vivo Models

Ubiquitination is a eukaryotic process of selective proteolysis, where a highly conserved ubiquitin protein is selectively added as a chain to the targeted to a protein for degradation. In recent years, the process of ubiquitination has been shown to be a critical mechanism that can affect essential signalling pathways, including apoptosis, cell cycle arrest and induction of the inflammatory response. Thus, alterations in the ubiquitination process can alter signalling pathways pivotal to numerous disease pathologies. This is clearly demonstrated in perturbations of ubiquitination in the NFκB giving rise to cancer and other immunological disease processes. To gain insight into pathways that require regulation by ubiquitination, our lab has directed focus on the highly conserved E3 ligase, Ariadne 2. Ariadne 2 is characterized as a putative RING finger E3 ligase and is part of the family of highly conserved RBR (RING-B-Box-RING) superfamily. The role of Ariadne 2 has been well studied in Drosophila melanogaster, however, little is known of the function of Ariadne 2 in mammalian systems. Therefore, the main objectives of the project are as follows: To determine the biological role of Ariadne 2, the role of Ariadne 2 in development and differentiation, and the consequences of in vivo loss of Ariadne 2 expression. We are currently investigating the role of Ariadne 2 as an E3 ligase and its involvement in the immune response. To date, we have shown that Ariadne 2 is ubiquitously expressed, especially in the brain, heart, spleen and thymus. For in vivo loss of function analysis, mice were generated by homologous recombination to be deficient for Ariadne 2. These deficient mice die prematurely soon after birth, suggesting a critical role for Ariadne 2 in development and survival. We are currently focusing on the role of Ariadne 2 in development and it’s role in immune pathologies, in particular, spontaneous autoimmunity, using both in vitro studies and in vivo models.

Abstract 206: Stem Cell-derived Exosomes Induce Cardiac Repair via mRNA Modification

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Prabhu Mathiyalagan ◽  
Yaxuan Liang ◽  
Adriano S Martins ◽  
Douglas W Losordo ◽  
Roger J Hajjar ◽  
...  
Keyword(s):  
Stem Cell ◽  
Myocardial Ischemia ◽  
Target Genes ◽  
Critical Role ◽  
Cell Communication ◽  
Target Cells ◽  
Mouse Heart ◽  
Loss Of Function

Exosomes are cell-derived nanovesicles that carry and shuttle microRNAs (miRNAs) to mediate cell-cell communication. Vast majority of cell types including cardiac myocytes and progenitors actively secrete exosomes, whose miRNA contents are altered after physiological or pathological changes such as myocardial ischemia (MI). In this new study, we have discovered that chemical modification to mRNAs is a novel regulator of ischemia-induced gene expression changes in the heart. We hypothesized that the benefits of human CD34 + stem cell-derived exosomes (CD34exo) are mediated by mRNA modifications in the target cells via miRNA delivery. MiRNA profiling and bioinformatic analysis identified that CD34exo is selectively enriched with a number of miRNAs that directly target genes implicated in regulation of mRNA modifications. Interestingly, under myocardial ischemia, there was a significant increase in mRNA modifications in the mouse heart, which was decreased by about 70% with CD34exo-treatment. In line with the in vivo MI data, in vitro hypoxic stimulation in neonatal / adult rodent myocytes and non-myocytes increased mRNA modifications and controls known regulators of those mRNA modifications. Loss-of-function studies for regulators of mRNA modifications attenuated hypoxia-induced changes to epitranscriptome indicating important roles for these molecules under stress conditions. Finally, using gain-of-function and loss-of-function studies, we demonstrate that miR-126, one of the most enriched miRNAs in CD34exo, plays a critical role in regulating the mRNA modifications. We conclude that miRNAs enriched in CD34exo mediate their cardioprotective effect at least in part, by regulating the mRNA epitranscriptome of the target cell. Our new data suggests hypoxia as a novel regulator of the mRNA epitranscriptome and provides novel insights to post-transcriptional gene regulation in the heart.

Sign in / Sign up

Export Citation Format

Share Document