A genome-wide DNA methylation signature for SETD1B-related syndrome

SETD1B is a component of a histone methyltransferase complex that specifically methylates Lys-4 of histone H3 (H3K4) and is responsible for the epigenetic control of chromatin structure and gene expression. De novo microdeletions encompassing this gene as well as de novo missense mutations were previously linked to syndromic intellectual disability (ID). Here, we identify a specific hypermethylation signature associated with loss of function mutations in the SETD1B gene which may be used as an epigenetic marker supporting the diagnosis of syndromic SETD1B-related diseases. We demonstrate the clinical utility of this unique epi-signature by reclassifying previously identified SETD1B VUS (variant of uncertain significance) in two patients

A genome-wide DNA methylation signature for SETD1B-related syndrome

SETD1B is a component of a histone methyltransferase complex that specifically methylates Lys-4 of histone H3 (H3K4) and is responsible for the epigenetic control of chromatin structure and gene expression. De novo microdeletions encompassing this gene as well as de novo missense mutations were previously linked to syndromic intellectual disability (ID). Here, we identify a specific hypermethylation signature associated with loss of function mutations in the SETD1B gene which may be used as an epigenetic marker supporting the diagnosis of syndromic SETD1B-related diseases. We demonstrate the clinical utility of this unique epi-signature by reclassifying previously identified SETD1B VUS (variant of uncertain significance) in two patients

Prevalence of Cataract Surgery and Visual Outcomes in Indian Immigrants in Singapore: The Singapore Indian Eye Study

10.1371/journal.pone.0075584PLoS ONE810-POLN

Bi-allelic Variants in the GPI Transamidase Subunit PIGK Cause a Neurodevelopmental Syndrome with Hypotonia, Cerebellar Atrophy, and Epilepsy

Glycosylphosphatidylinositol (GPI)-anchored proteins are critical for embryogenesis, neurogenesis, and cell signaling. Variants in several genes participating in GPI biosynthesis and processing lead to decreased cell surface presence of GPI-anchored proteins (GPI-APs) and cause inherited GPI deficiency disorders (IGDs). In this report, we describe 12 individuals from nine unrelated families with 10 different bi-allelic PIGK variants. PIGK encodes a component of the GPI transamidase complex, which attaches the GPI anchor to proteins. Clinical features found in most individuals include global developmental delay and/or intellectual disability, hypotonia, cerebellar ataxia, cerebellar atrophy, and facial dysmorphisms. The majority of the individuals have epilepsy. Two individuals have slightly decreased levels of serum alkaline phosphatase, while eight do not. Flow cytometric analysis of blood and fibroblasts from affected individuals showed decreased cell surface presence of GPI-APs. The overexpression of wild-type (WT) PIGK in fibroblasts rescued the levels of cell surface GPI-APs. In a knockout cell line, transfection with WT PIGK also rescued the GPI-AP levels, but transfection with the two tested mutant variants did not. Our study not only expands the clinical and known genetic spectrum of IGDs, but it also expands the genetic differential diagnosis for cerebellar atrophy. Given the fact that cerebellar atrophy is seen in other IGDs, flow cytometry for GPI-APs should be considered in the work-ups of individuals presenting this feature

Effects of Biliverdin Administration on Acute Lung Injury Induced by Hemorrhagic Shock and Resuscitation in Rats

Hemorrhagic shock and resuscitation induces pulmonary inflammation that leads to acute lung injury. Biliverdin, a metabolite of heme catabolism, has been shown to have potent cytoprotective, anti-inflammatory, and anti-oxidant effects. This study aimed to examine the effects of intravenous biliverdin administration on lung injury induced by hemorrhagic shock and resuscitation in rats. Biliverdin or vehicle was administered to the rats 1 h before sham or hemorrhagic shock-inducing surgery. The sham-operated rats underwent all surgical procedures except bleeding. To induce hemorrhagic shock, rats were bled to achieve a mean arterial pressure of 30 mmHg that was maintained for 60 min, followed by resuscitation with shed blood. Histopathological changes in the lungs were evaluated by histopathological scoring analysis. Inflammatory gene expression was determined by Northern blot analysis, and oxidative DNA damage was assessed by measuring 8-hydroxy-2' deoxyguanosine levels in the lungs. Hemorrhagic shock and resuscitation resulted in prominent histopathological damage, including congestion, edema, cellular infiltration, and hemorrhage. Biliverdin administration prior to hemorrhagic shock and resuscitation significantly ameliorated these lung injuries as judged by histopathological improvement. After hemorrhagic shock and resuscitation, inflammatory gene expression of tumor necrosis factor-alpha and inducible nitric oxide synthase were increased by 18- and 8-fold, respectively. Inflammatory gene expression significantly decreased when biliverdin was administered prior to hemorrhagic shock and resuscitation. Moreover, after hemorrhagic shock and resuscitation, lung 8-hydroxy-2' deoxyguanosine levels in mitochondrial DNA expressed in the pulmonary interstitium increased by 1.5-fold. Biliverdin administration prior to hemorrhagic shock and resuscitation decreased mitochondrial 8-hydroxy-2' deoxyguanosine levels to almost the same level as that in the control animals. We also confirmed that biliverdin administration after hemorrhagic shock and resuscitation had protective effects on lung injury. Our findings suggest that biliverdin has a protective role, at least in part, against hemorrhagic shock and resuscitation-induced lung injury through anti-inflammatory and anti-oxidant mechanisms

Zinc homeostasis and signaling in health and diseases: Zinc signaling

The essential trace element zinc (Zn) is widely required in cellular functions, and abnormal Zn homeostasis causes a variety of health problems that include growth retardation, immunodeficiency, hypogonadism, and neuronal and sensory dysfunctions. Zn homeostasis is regulated through Zn transporters, permeable channels, and metallothioneins. Recent studies highlight Zn’s dynamic activity and its role as a signaling mediator. Zn acts as an intracellular signaling molecule, capable of communicating between cells, converting extracellular stimuli to intracellular signals, and controlling intracellular events. We have proposed that intracellular Zn signaling falls into two classes, early and late Zn signaling. This review addresses recent findings regarding Zn signaling and its role in physiological processes and pathogenesis

De Novo and Bi-allelic Pathogenic Variants in NARS1 Cause Neurodevelopmental Delay Due to Toxic Gain-of-Function and Partial Loss-of-Function Effects

Aminoacyl-tRNA synthetases (ARSs) are ubiquitous, ancient enzymes that charge amino acids to cognate tRNA molecules, the essential first step of protein translation. Here, we describe 32 individuals from 21 families, presenting with microcephaly, neurodevelopmental delay, seizures, peripheral neuropathy, and ataxia, with de novo heterozygous and bi-allelic mutations in asparaginyl-tRNA synthetase (NARS1). We demonstrate a reduction in NARS1 mRNA expression as well as in NARS1 enzyme levels and activity in both individual fibroblasts and induced neural progenitor cells (iNPCs). Molecular modeling of the recessive c.1633C>T (p.Arg545Cys) variant shows weaker spatial positioning and tRNA selectivity. We conclude that de novo and bi-allelic mutations in NARS1 are a significant cause of neurodevelopmental disease, where the mechanism for de novo variants could be toxic gain-of-function and for recessive variants, partial loss-of-function

De Novo and Bi-allelic Pathogenic Variants in NARS1 Cause Neurodevelopmental Delay Due to Toxic Gain-of-Function and Partial Loss-of-Function Effects.

Aminoacyl-tRNA synthetases (ARSs) are ubiquitous, ancient enzymes that charge amino acids to cognate tRNA molecules, the essential first step of protein translation. Here, we describe 32 individuals from 21 families, presenting with microcephaly, neurodevelopmental delay, seizures, peripheral neuropathy, and ataxia, with de novo heterozygous and bi-allelic mutations in asparaginyl-tRNA synthetase (NARS1). We demonstrate a reduction in NARS1 mRNA expression as well as in NARS1 enzyme levels and activity in both individual fibroblasts and induced neural progenitor cells (iNPCs). Molecular modeling of the recessive c.1633C>T (p.Arg545Cys) variant shows weaker spatial positioning and tRNA selectivity. We conclude that de novo and bi-allelic mutations in NARS1 are a significant cause of neurodevelopmental disease, where the mechanism for de novo variants could be toxic gain-of-function and for recessive variants, partial loss-of-function

Guanosine stimulates neurite outgrowth in PC12 cells via activation of heme oxygenase and cyclic GMP

Undifferentiated rat pheochromocytoma (PC12) cells extend neurites when cultured in the presence of nerve growth factor (NGF). Extracellular guanosine synergistically enhances NGF-dependent neurite outgrowth. We investigated the mechanism by which guanosine enhances NGF-dependent neurite outgrowth. Guanosine administration to PC12 cells significantly increased guanosine 3-5-cyclic monophosphate (cGMP) within the first 24 h whereas addition of soluble guanylate cyclase (sGC) inhibitors abolished guanosine-induced enhancement of NGF-dependent neurite outgrowth. sGC may be activated either by nitric oxide (NO) or by carbon monoxide (CO). \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$N^{\omega }$$ \end{document}-Nitro-l-arginine methyl ester (l-NAME), a non-isozyme selective inhibitor of nitric oxide synthase (NOS), had no effect on neurite outgrowth induced by guanosine. Neither nNOS (the constitutive isoform), nor iNOS (the inducible isoform) were expressed in undifferentiated PC12 cells, or under these treatment conditions. These data imply that NO does not mediate the neuritogenic effect of guanosine. Zinc protoporphyrin-IX, an inhibitor of heme oxygenase (HO), reduced guanosine-dependent neurite outgrowth but did not attenuate the effect of NGF. The addition of guanosine plus NGF significantly increased the expression of HO-1, the inducible isozyme of HO, after 12 h. These data demonstrate that guanosine enhances NGF-dependent neurite outgrowth by first activating the constitutive isozyme HO-2, and then by inducing the expression of HO-1, the enzymes responsible for CO synthesis, thus stimulating sGC and increasing intracellular cGMP