Browse
Submit Data
Databases
API
Help

Dataset Information

20 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Liver-directed gene therapy for ornithine aminotransferase deficiency.

ABSTRACT: Gyrate atrophy of choroid and retina (GACR) is a chorioretinal degeneration caused by pathogenic variants in the gene encoding ornithine aminotransferase (OAT), an enzyme mainly expressed in liver. Affected patients have increased ornithine concentrations in blood and other body fluids and develop progressive constriction of vision fields leading to blindness. Current therapies are unsatisfactory and better treatments are highly needed. In two mouse models of OAT deficiency that recapitulates biochemical and retinal changes of GACR, we investigated the efficacy of an intravenously injected serotype 8 adeno-associated (AAV8) vector expressing OAT under the control of a hepatocyte-specific promoter. Following injections, OAT-deficient mice showed reductions of ornithine concentrations in blood and eye cups compared to control mice injected with a vector expressing green fluorescent protein. AAV-injected mice showed improved electroretinogram response and partial restoration of retinal structure up to one-year post-injection. In summary, hepatic OAT expression by AAV8 was effective at correction of hyperornithinemia and improved function and structure of the retina. In conclusion, this study provides proof-of-concept of efficacy of liver-directed AAV-mediated gene therapy of GACR.

SUBMITTER: Dr. Iolanda Boffa

PROVIDER: S-SCDT-10_15252-EMMM_202217033 | biostudies-other |

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Ornithine aminotransferase supports polyamine synthesis in pancreatic cancer

Project description:Pancreatic ductal adenocarcinoma (PDA) cells have a distinct dependence on de novo ornithine synthesis from glutamine via ornithine aminotransferase (OAT), which supports polyamine synthesis and is required for tumor growth. This directional OAT activity is normally largely restricted to infancy and contrasts with the reliance of most adult normal tissues and other cancer types on arginase (ARG) to generate arginine-derived ornithine, the substrate for polyamine synthesis. This dependence associates with arginine depletion in PDA tumor microenvironment, and is driven by mutant KRAS, which induces the expression of OAT and polyamine synthesis enzymes, including the rate-limiting enzyme ornithine decarboxylase-1 (ODC1). Loss of OAT, but not ARG2, largely mimics loss of ODC1, altering the transcriptional profiles in PDA cells, which in turn correlate with alterations in open chromatin states.

2023-01-01 | GSE193411 | GEO

Targeted mRNA Therapy for Ornithine Transcarbamylase Deficiency.

Project description:We describe a novel, two-nanoparticle mRNA delivery system and show that it is highly effective as a means of intracellular enzyme replacement therapy (i-ERT) using a murine model of ornithine transcarbamylase deficiency (OTCD). Our Hybrid mRNA Technology delivery system (HMT) comprises an inert lipid nanoparticle that protects the mRNA from nucleases in the blood as it distributes to the liver and a polymer micelle that targets hepatocytes and triggers endosomal release of mRNA. This results in high-level synthesis of the desired protein specifically in the liver. HMT delivery of human OTC mRNA normalizes plasma ammonia and urinary orotic acid levels, and leads to a prolonged survival benefit in the murine OTCD model. HMT represents a unique, non-viral mRNA delivery method that allows multi-dose, systemic administration for treatment of single-gene inherited metabolic diseases.

| S-EPMC5910669 | biostudies-literature

A neonate with ornithine aminotransferase deficiency; insights on the hyperammonemia-associated biochemical phenotype of gyrate atrophy.

Project description:Gyrate atrophy of the choroid and retina (GACR) secondary to deficiency of ornithine aminotransferase (OAT) is a rare autosomal recessive metabolic disorder usually diagnosed in childhood when patients develop myopia and a characteristic retinal degeneration accompanied by hyperornithinemia. Plasma ammonia is normal or sub-normal after the neonatal period. A few GACR patients present in early infancy with hyperammonemia, encephalopathy and a biochemical profile of low plasma ornithine, citrulline and arginine, with increased urinary excretion of homocitrulline and orotic acid, resembling a primary urea cycle disorder. In these patients, ornithine levels do not increase until late infancy or following arginine or citrulline supplementation. We describe a patient with OAT deficiency who presented in the first month of life with episodes of lethargy, vomiting, and hypothermia. He had two episodes of hyperammonemia associated with subnormal levels of plasma ornithine, citrulline and arginine as well as elevated urinary excretion of homocitrulline and orotic acid. Unlike previously reported cases, intermittent hyperornithinemia was observed prior to the first hyperammonemic episode and citrulline supplementation. The latter alleviated the symptoms, normalized ammonia level, and led to increased plasma ornithine concentration. Furthermore, despite a protein restricted diet and ammonia scavenger treatment, continued supplemental citrulline was necessary to prevent hyperammonemia. Molecular analysis confirmed OAT deficiency, differentiating it from proximal urea cycle disorders and deficiency of the mitochondrial ornithine transporter, ORC1, (Hyperammonemia-Hyperornithinemia-Homocitrullinuria syndrome).SynopsisHyperornithinemia alternating with hypoornithinemia and hyperammonemia in a neonatal-onset case of gyrate atrophy with ornithine aminotransferase deficiency.

| S-EPMC9248225 | biostudies-literature

Ornithine aminotransferase versus GABA aminotransferase: implications for the design of new anticancer drugs.

Project description:Ornithine aminotransferase (OAT) and ?-aminobutyric acid aminotransferase (GABA-AT) are classified under the same evolutionary subgroup and share a large portion of structural, functional, and mechanistic features. Therefore, it is not surprising that many molecules that bind to GABA-AT also bind well to OAT. Unlike GABA-AT, OAT had not been viewed as a potential therapeutic target until recently; consequently, the number of therapeutically viable molecules that target OAT is very limited. In this review the two enzymes are compared with respect to their active-site structures, catalytic and inactivation mechanisms, and selective inhibitors. Insight is offered that could aid in the design and development of new selective inhibitors of OAT for the treatment of cancer.

| S-EPMC4415689 | biostudies-literature

Ornithine-?-Aminotransferase Inhibits Neurogenesis During Xenopus Embryonic Development.

Project description:In humans, deficiency of ornithine-?-aminotransferase (OAT) results in progressive degeneration of the neural retina (gyrate atrophy) with blindness in the fourth decade. In this study, we used the Xenopus embryonic developmental model to study functions of the OAT gene on embryonic development.We cloned and sequenced full-length OAT cDNA from Xenopus oocytes (X-OAT) and determined X-OAT expression in various developmental stages of Xenopus embryos and in a variety of adult tissues. The phenotype, gene expression of neural developmental markers, and enzymatic activity were detected by gain-of-function and loss-of-function manipulations.We showed that X-OAT is essential for Xenopus embryonic development, and overexpression of X-OAT produces a ventralized phenotype characterized by a small head, lack of axial structure, and defective expression of neural developmental markers. Using X-OAT mutants based on mutations identified in humans, we found that substitution of both Arg 180 and Leu 402 abrogated both X-OAT enzymatic activity and ability to modulate the developmental phenotype. Neurogenesis is inhibited by X-OAT during Xenopus embryonic development.Neurogenesis is inhibited by X-OAT during Xenopus embryonic development, but it is essential for Xenopus embryonic development. The Arg 180 and Leu 402 are crucial for these effects of the OAT molecule in development.

| S-EPMC4554259 | biostudies-literature

Frequency and Pathophysiology of Acute Liver Failure in Ornithine Transcarbamylase Deficiency (OTCD).

Project description:BACKGROUND:Acute liver failure (ALF) has been reported in ornithine transcarbamylase deficiency (OTCD) and other urea cycle disorders (UCD). The frequency of ALF in OTCD is not well-defined and the pathogenesis is not known. AIM:To evaluate the prevalence of ALF in OTCD, we analyzed the Swiss patient cohort. Laboratory data from 37 individuals, 27 females and 10 males, diagnosed between 12/1991 and 03/2015, were reviewed for evidence of ALF. In parallel, we performed cell culture studies using human primary hepatocytes from a single patient treated with ammonium chloride in order to investigate the inhibitory potential of ammonia on hepatic protein synthesis. RESULTS:More than 50% of Swiss patients with OTCD had liver involvement with ALF at least once in the course of disease. Elevated levels of ammonia often correlated with (laboratory) coagulopathy as reflected by increased values for international normalized ratio (INR) and low levels of hepatic coagulation factors which did not respond to vitamin K. In contrast, liver transaminases remained normal in several cases despite massive hyperammonemia and liver involvement as assessed by pathological INR values. In our in vitro studies, treatment of human primary hepatocytes with ammonium chloride for 48 hours resulted in a reduction of albumin synthesis and secretion by approximately 40%. CONCLUSION:In conclusion, ALF is a common complication of OTCD, which may not always lead to severe symptoms and may therefore be underdiagnosed. Cell culture experiments suggest an ammonia-induced inhibition of hepatic protein synthesis, thus providing a possible pathophysiological explanation for hyperammonemia-associated ALF.

| S-EPMC4829252 | biostudies-literature

Gene Mutation Analysis and Prenatal Diagnosis of the Ornithine Transcarbamylase (OTC) Gene in Two Families with Ornithine Transcarbamylase Deficiency.

Project description:BACKGROUND The aim of this study was to perform gene detection in 2 clinical cases of highly suspected ornithine transcarbamylase deficiency (OTCD) pediatric patients by first-generation sequencing technology in order to confirm the pathogenic genetic factors of their families and allow the families to undergo genetic counselling and prenatal diagnosis. MATERIAL AND METHODS The peripheral DNA samples of 2 children with highly suspected OTCD (the probands) and their parents were collected. DNA fragments corresponding to exons 1-10 of the OTC gene from the samples were amplified using polymerase chain reaction (PCR), and then subjected to Sanger sequencing to confirm the pathogenic mutation sites. RESULTS The probands were both confirmed to have OTCD. The proband in Family 1 was a male carrying a c.867+1G>C mutation at a splice site within the OTC gene. The gene detection results of amniotic fluid cells at 16 weeks of pregnancy showed that the fetus was a male who also carried the c.867+1G>C mutation. The proband in Family 2 was a male carrying a c.782T>C(p. I261T) mutation in the OTC gene. The gene detection results of amniotic fluid cells at 18 weeks showed that the fetus was a male without pathogenic mutations in the OTC gene. The gene detection results of peripheral blood from the fetus after birth were consistent with those obtained from amniotic fluid cells. CONCLUSIONS Pediatric children who are clinically suspected of OTCD can receive a definitive diagnosis through OTC gene detection.

| S-EPMC6354644 | biostudies-literature

Targeting the <i>Apoa1</i> locus for liver-directed gene therapy.

Project description:Clinical application of somatic genome editing requires therapeutics that are generalizable to a broad range of patients. Targeted insertion of promoterless transgenes can ensure that edits are permanent and broadly applicable while minimizing risks of off-target integration. In the liver, the Albumin (Alb) locus is currently the only well-characterized site for promoterless transgene insertion. Here, we target the Apoa1 locus with adeno-associated viral (AAV) delivery of CRISPR-Cas9 and achieve rates of 6% to 16% of targeted hepatocytes, with no evidence of toxicity. We further show that the endogenous Apoa1 promoter can drive robust and sustained expression of therapeutic proteins, such as apolipoprotein E (APOE), dramatically reducing plasma lipids in a model of hypercholesterolemia. Finally, we demonstrate that Apoa1-targeted fumarylacetoacetate hydrolase (FAH) can correct and rescue the severe metabolic liver disease hereditary tyrosinemia type I. In summary, we identify and validate Apoa1 as a novel integration site that supports durable transgene expression in the liver for gene therapy applications.

| S-EPMC8166646 | biostudies-literature

Antepartum ornithine transcarbamylase deficiency.

Project description:Ornithine transcarbamylase deficiency (OTCD) is the most common type urea cycle enzyme deficiencies. This syndrome results from a deficiency of the mitochondrial enzyme ornithine transcarbamylase, which catalyzes the conversion of ornithine and carbamoyl phosphate to citrullin. Our case was a 28-year-old female diagnosed with OTCD following neurocognitive deficit during her first pregnancy. Although hyperammonemia was suspected as the cause of the patient's mental changes, there was no evidence of chronic liver disease. Plasma amino acid and urine organic acid analysis revealed OTCD. After combined modality treatment with arginine, sodium benzoate and hemodialysis, the patient's plasma ammonia level stabilized and her mental status returned to normal. At last she recovered without any damage left.

| S-EPMC4337171 | biostudies-literature

Suppression of Hepatocellular Carcinoma by Inhibition of Overexpressed Ornithine Aminotransferase.

Project description:Hepatocellular carcinoma is the second leading cause of cancer death worldwide. DNA microarray analysis identified the ornithine aminotransferase (OAT) gene as a prominent gene overexpressed in hepatocellular carcinoma (HCC) from Psammomys obesus. In vitro studies demonstrated inactivation of OAT by gabaculine (1), a neurotoxic natural product, which suppressed in vitro proliferation of two HCC cell lines. Alpha-fetoprotein (AFP) secretion, a biomarker for HCC, was suppressed by gabaculine in both cell lines, but not significantly. Because of the active site similarity between GABA aminotransferase (GABA-AT) and OAT, a library of 24 GABA-AT inhibitors was screened to identify a more selective inhibitor of OAT. (1S,3S)-3-Amino-4-(hexafluoropropan-2-ylidene)cyclopentane-1-carboxylic acid (2) was found to be an inactivator of OAT that only weakly inhibits GABA-AT, l-aspartate aminotransferase, and l-alanine aminotransferase. In vitro administration of 2 significantly suppressed AFP secretion in both Hep3B and HepG2 HCC cells; in vivo, 2 significantly suppressed AFP serum levels and tumor growth in HCC-harboring mice, even at 0.1 mg/kg. Overexpression of the OAT gene in HCC and the ability to block the growth of HCC by OAT inhibitors support the role of OAT as a potential therapeutic target to inhibit HCC growth. This is the first demonstration of suppression of HCC by an OAT inactivator.

| S-EPMC4538432 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data