Fumarylacetoacetate Hydrolase Research Articles

Fumarylacetoacetate hydrolase (FAH): a candidate host gene associated with susceptibility to tuberculosis

Abstract Tuberculosis (TB) disease remains the leading cause of mortality from an infectious disease globally, with an estimated 1.6 million deaths in 2021. TB is caused by infection with Mycobacterium tuberculosis (Mtb), resulting in variable outcomes from asymptomatic latent infection to clinical TB disease. However, most individuals exposed to Mtb never develop clinical disease. We hypothesize that host factors, including metabolic pathways, determine the outcome of Mtb infection. Based on prior data from human cohorts we observed an association between impaired tyrosine metabolism and progression to TB disease. We then reanalyzed a public dataset of Mtb-infected monocyte derived dendritic cells (DCs) and found that stimulation with either live or heat-inactivated Mtb resulted in downregulation of FAH (fumarylacetoacetate hydrolase), which encodes the last enzyme in the tyrosine catabolism pathway. Next, we used gene editing of FAH in conditionally immortalized myeloid progenitors (CIM) from mice to test whether downregulation of the FAH gene is associated with higher susceptibility to Mtb. We generated three independent fah-edited CIM lines, with two lines showing editing efficiency above 90%. We infected wildtype and fah-edited CIMs with an H37Rv-lux Mtb strain and detected significantly higher Mtb growth in fah-edited CIMs compared to wildtype CIMs (p=0.004). We also successfully optimized CRISPR in primary human monocyte derived DCs and macrophages to define the role of FAH during infection in physiologically relevant myeloid cell types. Our data suggest that FAH deletion compromises immune control of Mtb. We are currently exploring the immunoregulatory roles of FAH during Mtb infection, including inflammasome activation.

Optimization of CRISPR-Cas9 Mediated Knockout Protocol in Primary Human Myeloid Cells

Abstract Myeloid cells are an important player in the immune system, and form the first line of defense against pathogens, such as Mycobacterium tuberculosis (Mtb), the causative pathogen for tuberculosis (TB) disease. They include macrophages, a target of Mtbinfection, and dendritic cells (DCs), which present Mtb-derived antigens to prime and activate T cells. In order to investigate myeloid-specific host factors involved in the response to Mtbinfection, we sought to optimize a protocol to genetically edit primary human monocyte-derived DCs and macrophages for subsequent infection experiments with Mtb. We built on prior published protocol by Hiatt, et al. to edit monocyte-derived DCs and macrophages using nucleofection with ribonucleoproteins (RNP), which are Cas9 recombinant protein complexed with multiplexed guide RNA (gRNA) molecules. We tested reaction volume, RNP concentration, rest time, and nucleofection programs. We found that a molar ratio of Cas9:gRNA was most efficient at 1:2 at 1.8μM final RNP concentration in combination with a 2hr rest time after nucleofection before adding differentiation supplement. Lonza nucleofection program EA100 proved to be the optimal program with the most recovered cells. In conclusion, we optimized a robust protocol for editing and culturing edited primary monocyte-derived DCs and macrophages. This opens opportunities for interrogation of candidate TB risk genes such as Fumarylacetoacetate hydrolase (FAH). These cells can now be used for mechanistic studies of Mtbinfection to define mechanisms of pathogenesis.

Abstract 35: Development of novel human hepatocellular carcinoma models using genetically modified human hepatocytes in FSRG humanized liver mice

Abstract The incidence of liver cancer is growing worldwide, and it is estimated that by 2025, over 1 million individuals will be affected by liver cancer every year. Hepatocellular carcinoma (HCC) accounts for about 90% of primary liver cancer cases and is one of the leading causes of death from cancer worldwide. Establishing animal models that faithfully replicate the human disease is critical to improve our understanding of HCC pathogenesis and to test new therapeutic strategies. Here, we describe a novel human HCC model using genetically modified human hepatocytes in a humanized liver mouse. Primary human hepatocytes (PHH) were modified ex vivo through lentivirus or Lipid Nanoparticle (LNP)-mediated delivery of CRISPR/Cas9 components, resulting in over-expression of oncogenes or inactivation of tumor suppressor genes. These genetically engineered PHH were engrafted into the livers of FSRG (FAH−/−, SIRPahu/hu, RAG2−/−, IL2Rg−/−) mice, developed by Regeneron VelociGene technology, in which mouse liver parenchyma can be replaced with human hepatocytes. Tumor formation was validated in livers engrafted with human hepatocytes after different combinations of genetic modification, including over-expression of cMYC plus HRASv12, and cMYC over-expression together with p53 KO. Tumor progression could be monitored by measuring human Alpha Fetoprotein (AFP) in serum of engrafted mice. Liver tumors were positive for fumarylacetoacetate hydrolase (FAH) and human Asialoglycoprotein Receptor 1 (ASGR1), confirming their human origin, as well as the proliferation marker, Ki67, and Glypican-3 (GPC3), which is frequently over-expressed in HCC and a potential therapeutic target. In these studies, mice were engrafted with a mix of lentivirus-transduced and non-transduced hepatocytes, resulting in humanized livers with both normal and transformed human hepatocytes, providing an ideal system to recapitulate neoplastic transformation and clonal expansion of human hepatocytes carrying oncogenic mutations as well as to test the specificity of novel therapies. By combining genetic manipulation of human hepatocytes with the FSRG humanized liver mouse platform, we have established a flexible system to model clinically relevant combinations of HCC mutations for both new target discovery and therapeutic testing. Citation Format: Marisa Carbonaro, Ciro Bonetti, Hui Huang, Kehui Wang, Mathieu Desclaux, Guochun Gong, John C. Lin, Christopher Daly, Gavin Thurston, Zhe Li. Development of novel human hepatocellular carcinoma models using genetically modified human hepatocytes in FSRG humanized liver mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 35.

Hereditary Tyrosinemia Type 1 Mice under Continuous Nitisinone Treatment Display Remnants of an Uncorrected Liver Disease Phenotype

Hereditary tyrosinemia type 1 (HT1) is a genetic disorder of the tyrosine degradation pathway (TIMD) with unmet therapeutic needs. HT1 patients are unable to fully break down the amino acid tyrosine due to a deficient fumarylacetoacetate hydrolase (FAH) enzyme and, therefore, accumulate toxic tyrosine intermediates. If left untreated, they experience hepatic failure with comorbidities involving the renal and neurological system and the development of hepatocellular carcinoma (HCC). Nitisinone (NTBC), a potent inhibitor of the 4-hydroxyphenylpyruvate dioxygenase (HPD) enzyme, rescues HT1 patients from severe illness and death. However, despite its demonstrated benefits, HT1 patients under continuous NTBC therapy are at risk to develop HCC and adverse reactions in the eye, blood and lymphatic system, the mechanism of which is poorly understood. Moreover, NTBC does not restore the enzymatic defects inflicted by the disease nor does it cure HT1. Here, the changes in molecular pathways associated to the development and progression of HT1-driven liver disease that remains uncorrected under NTBC therapy were investigated using whole transcriptome analyses on the livers of Fah- and Hgd-deficient mice under continuous NTBC therapy and after seven days of NTBC therapy discontinuation. Alkaptonuria (AKU) was used as a tyrosine-inherited metabolic disorder reference disease with non-hepatic manifestations. The differentially expressed genes were enriched in toxicological gene classes related to liver disease, liver damage, liver regeneration and liver cancer, in particular HCC. Most importantly, a set of 25 genes related to liver disease and HCC development was identified that was differentially regulated in HT1 vs. AKU mouse livers under NTBC therapy. Some of those were further modulated upon NTBC therapy discontinuation in HT1 but not in AKU livers. Altogether, our data indicate that NTBC therapy does not completely resolves HT1-driven liver disease and supports the sustained risk to develop HCC over time as different HCC markers, including Moxd1, Saa, Mt, Dbp and Cxcl1, were significantly increased under NTBC.

Clinical features and genetic analysis of a child with acute form of Tyrosinemia type I due to a novel variant of FAH gene

To analyze the clinical phenotype and genetic basis for a child with acute form of tyrosinemia type I (TYRSN1). A child with TYRSN1 who presented at the Gansu Provincial Maternal and Child Health Care Hospital in October 2020 was selected as the subject. The child was subjected to tandem mass spectrometry (MS-MS) and urine gas chromatography-mass spectrometry (GC-MS) for the detection of inherited metabolic disorders, in addition with whole exome sequencing (WES). Candidate variants were validated by Sanger sequencing. The child's clinical features included abdominal distension, hepatomegaly, anemia and tendency of bleeding. By mass spectrometry analysis, her serum and urine tyrosine and succinylacetone levels have both exceeded the normal ranges. WES and Sanger sequencing revealed that she has harbored c.1062+5G>A and c.943T>C (p.Cys315Arg) compound heterozygous variants of the FAH gene, which were inherited from her father and mother, respectively. Among these, the c.943T>C was unreported previously. Considering her clinical phenotype and result of genetic testing, the child was diagnosed with TYRSN1 (acute type). The compound heterozygous variants of the FAH gene probably underlay the disease in this child. Above finding has further expanded the spectrum of FAH gene variants, and provided a basis for accurate treatment, genetic counseling and prenatal diagnosis for her family.

Establishment of a Fah-LSL mouse model to study BEC-to-hepatocyte conversion.

The liver consists predominantly of hepatocytes and biliary epithelial cells (BECs), which serve distinct physiological functions. Although hepatocytes primarily replenish their own population during homeostasis and injury repair, recent findings have suggested that BECs can transdifferentiate into hepatocytes when hepatocyte-mediated liver regeneration is impaired. However, the cellular and molecular mechanisms governing this BEC-to-hepatocyte conversion remain poorly understood largely because of the inefficiency of existing methods for inducing lineage conversion. Therefore, this study introduces a novel mouse model engineered by the Zhou's lab, where hepatocyte senescence is induced by the deletion of the fumarylacetoacetate (Fah) gene. This model facilitates the efficient conversion of BECs to hepatocytes and allows for the simultaneous lineage tracing of BECs; consequently, a transitional liver progenitor cell population can be identified during lineage conversion. This study also outlines the technical procedures for utilizing this model to determine the underlying cellular and molecular mechanisms of BEC-to-hepatocyte conversion and provides new insights into liver regeneration and its underlying molecular mechanism.

Crystal Structure of l-2,4-Diketo-3-deoxyrhamnonate Hydrolase Involved in the Nonphosphorylated l-Rhamnose Pathway from Bacteria.

2,4-Diketo-3-deoxy-l-rhamnonate (L-DKDR) hydrolase (LRA6) catalyzes the hydrolysis reaction of L-DKDR to pyruvate and l-lactate in the nonphosphorylated l-rhamnose pathway from bacteria and belongs to the fumarylacetoacetate hydrolase (FAH) superfamily. Most of the members of the FAH superfamily are involved in the microbial degradation of aromatic substances and share low sequence similarities with LRA6, by which the underlying catalytic mechanism remains unknown at the atomic level. We herein elucidated for the first time the crystal structures of LRA6 from Sphingomonas sp. without a ligand and in complex with pyruvate, in which a magnesium ion was coordinated with three acidic residues in the catalytic center. Structural, biochemical, and phylogenetic analyses suggested that LRA6 is a close but distinct subfamily of the fumarylpyruvate hydrolase (FPH) subfamily, and amino acid residues at equivalent position to 84 in LRA6 are related to different substrate specificities between them (Leu84 and Arg86 in LRA6 and FPH, respectively). Structural transition induced upon the binding of pyruvate was observed within a lid-like region, by which a glutamate-histidine dyad that is critical for catalysis was arranged sufficiently close to the ligand. Among several hydroxylpyruvates (2,4-diketo-5-hydroxycarboxylates), L-DKDR with a C6 methyl group was the best substrate for LRA6, conforming to the physiological role. Significant activity was also detected in acylpyruvate including acetylpyruvate. The structural analysis presented herein provides a more detailed understanding of the molecular evolution and physiological role of the FAH superfamily enzymes (e.g., the FAH like-enzyme involved in the mammalian l-fucose pathway).

Identification and functional characterization of a novel homozygous intronic variant in the fumarylacetoacetate hydrolase gene in a Chinese patient with tyrosinemia type 1

BackgroundHereditary tyrosinemia type 1 (HT1; OMIM# 276700) is a genetic metabolism disorder caused by disease-causing variants in the fumarylacetoacetate hydrolase (FAH) gene encoding the last enzyme of the tyrosine catabolic pathway. Herein, we describe the clinical features and genetic characteristics of HT1 in a five years and seven months old Chinese patient.MethodsAfter clinical diagnosis of the proband with HT1, genetic testing was performed by Sanger sequencing of the FAH gene in all family members. Functional analysis of the disease-causing variant was performed by cDNA sequencing to understand the effect of the variant on FAH transcript. To further predict the variant effect, we used Human Splicing Finder (HSF) and PyMol in silico analysis.ResultsWe identified a novel previously undescribed intronic variant in the FAH gene (c.914-1G>A). It was detected in a child who was homozygous for the variant and had the clinical presentation of HT1. cDNA sequencing showed that this splice-junction variant affected the transcription of FAH by formation of two different transcripts. Our observations and laboratory experiments were in line with in silico methods.ConclusionsOur study provides new insight into the HT1 variant spectrum and a better understanding of this disease in the Chinese population. This will be useful for molecular diagnosis in our country in cases where premarital screening, prenatal diagnosis and preimplantation genetic diagnosis are planned.

The compound heterozygous mutations of c.607G>a and c.657delC in the FAH gene are associated with renal damage with hereditary tyrosinemia type 1 (HT1).

Hereditary tyrosinemia type 1 (HT1) is a rare inherited metabolic disease characterized by severe liver and renal dysfunction. Early identification in affected children is critical for improved treatment options and prognosis. In this study, we identified novel compound heterozygous mutations (NM_000137: c.657delC (p.K220Rfs*12) and c.607G>A (p.A203T)) in the fumarylacetoacetate hydrolase (FAH) gene in a family. We also characterized the clinical phenotype of the proband and verified the pathogenic effects of the mutations. Furthermore, we explored the pathogenic mechanism of renal injury through renal biopsy pathology and cell-based in vitro assays. Our study aims to verify the association between novel fumarylacetoacetate hydrolase (FAH) variants and HT1, confirm the pathogenic effects of the mutations and explore the pathogenic mechanism of renal injury. We showed these FAH mutations were inherited in an autosomal recessive manner and resulted in abnormal FAH protein expression and dysfunction, leading to fumarylacetoacetate (FAA) accumulation. The proband also showed apparent renal injury, including glomerular filtration barrier dysfunction and abnormal tubular protein reabsorption. These observations may provide deeper insights on disease pathogenesis and identify potential therapeutic approaches for HT1 from a genetic perspective. Similarly, we hope to provide valuable information for genetic counseling and prenatal diagnostics.

Initial presentation, management and follow-up data of 33 treated patients with hereditary tyrosinemia type 1 in the absence of newborn screening

Hereditary tyrosinemia type 1 (HT1) is a rare autosomal recessive disorder of phenylalanine and tyrosine catabolism due to a deficiency of fumarylacetoacetate hydrolase. HT1 has a large clinical spectrum with acute forms presenting before six months of age, subacute forms with initial symptoms occurring between age 6 and 12 months, and chronic forms after 12 months of age. Without treatment, HT1 results in the accumulation of toxic metabolites leading to liver disease, proximal tubular dysfunction, and porphyria-like neurological crises. Since the early nineties, the outcome of HT1 has dramatically changed due to its treatment with 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC, nitisinone). In some countries, HT1 is included in the newborn screening program based on the analysis of succinylacetone concentration on dried blood spots.In the present study, we report clinical and laboratory parameters data on 33 HT1 patients focusing on clinical presentation and therapeutic management at the time of diagnosis. Eighteen patients were diagnosed with the acute form (median age at presentation 2.5 months), 6 with the subacute form (median age at presentation 10 months), and 5 with the chronic form of HT1 (median age at presentation 15 months). Four patients were diagnosed pre-symptomatically in the setting of a family history of HT1. Among the 29 symptomatic patients, hepatomegaly was found in 83% of patients and prolonged coagulation times due to hepatocellular insufficiency was observed in 93% of patients. HT1 diagnosis was confirmed by increased urine succinylacetone in all patients. All patients but 2 were treated with nitisinone immediately at diagnosis. During follow-up, 2 patients received liver transplant for high grade dysplasia or hepatocellular carcinoma, 10 patients exhibited some form of neurocognitive impairments.Our data confirm that HT1 is a severe treatable liver disease that should be detected at the earliest, ideally by newborn screening and appropriately treated.

S3069 Lifesaving but Tiresome Treatment for Tyrosinemia Type 1

Introduction: Tyrosinemia type I (HT1) is a rare autosomal recessive condition caused by a genetic mutation disrupting proper functioning of the fumarylacetoacetate hydrolase (FAH) enzyme, the terminal enzyme in the tyrosine catabolism pathway. The below case exemplifies the difficulty for adherence as children transition to adulthood of the standard therapy that prolongs life and decreases need for orthotopic liver transplantation (OLT). Case Description/Methods: A 23-year-old male with known tyrosinemia type I presents with progressively worsening back, lower extremity, and abdominal pain over the last six months. He had been lost to follow-up from Genetics clinic for the last ten years. He adhered to nitisinone therapy and diet modifications until around five years ago. The patient was admitted to the hospital for neurological crises due to non-adherence to HT1 therapy. On admission, vital signs were stable and his physical exam significant for mild tenderness of abdomen at RUQ and tenderness in the lumbar and thoracic region of back. Pertinent lab findings were albumin of 3.2, alkaline phosphatase of 356. AST, ALT, Bili, CBC, BMP WNL. Amino acid panel found tyrosine level of 62. AFP level of 188. MRI Abdomen with and without contrast found cirrhotic liver morphology, developing portal hypertension (borderline enlarged spleen, collateral vasculature, but no ascites), and a lesion of hepatic segment 8 measuring 2.3cm x 1.4cm in diameter. Patient was planned to be restarted on nitisinone with pending further evaluation of liver lesion. (Figure) Discussion: The above case demonstrates a patient with the rare genetic disorder Tyrosinemia type 1 with non-adherence to nitisinone and diet modification therapies. The presentation of neurological crises and abdominal pain with development of hepatomas/hepatocellular carcinoma (HCC) is typical for untreated or non-adherent patients with HT1. Nitisinone has been shown to be highly effective for this condition with 4-year survival rates of 94% compared to 29% of diet modification alone. Prior to nitisinone therapy, most patients required OLT. Despite the clear benefits, recent evidence is finding increasing non-adherence as patients grow older into adolescence and adulthood. This is consistent with adherence problems with early diagnosis chronic diseases with long-term therapies. More research is needed to elucidate major barriers for non-compliance and to refine guidelines regarding frequency of follow-up and monitoring of serum AFP to screen for HCC and encourage compliance.Figure 1.: MRI Abdomen with contrast with findings of a hepatic lesion on segment 8.

Diagnostic tardif de la tyrosinémie héréditaire de type I, le cas de deux faux jumeaux

AbstractHereditary tyrosinemia type 1 (TH1) is an autosomal recessive inherited aminoacidopathy caused by a deficiency of an enzyme involved in the last step of tyrosine catabolism called fumarylacetoacetate hydrolase (FAH). The accumulation of metabolites fumarylacetoacetate, succinylacetoacetate and succinylacetone generates renal and hepatic toxicity, hence the name hepatorenal tyrosinemia. In the context of targeted screening, two male fraternal twins of consanguineous parents and with a history of death in the siblings, as well as a cousin, were diagnosed for TH1. The dosage of urinary succinylacetone (SA) came back for the first twin in favor of tyrosinemia, but the dosage in the second twin was positive only after the fourth determination confirming the pathology diagnosis. Classically, the SA rate rises from the first days of life; the heterogeneity of the mutations affecting the FAH gene can explain this phenotypic fluctuation also the action of modulating factors still little known without any reported correlation between the genotype and the phenotype. The genetic study revealed a frequent genetic mutation of the FAH gene.

In vivo lentiviral vector gene therapy to cure hereditary tyrosinemia type 1 and prevent development of precancerous and cancerous lesions

Conventional therapy for hereditary tyrosinemia type-1 (HT1) with 2-(2-nitro-4-trifluoromethylbenzoyl)−1,3-cyclohexanedione (NTBC) delays and in some cases fails to prevent disease progression to liver fibrosis, liver failure, and activation of tumorigenic pathways. Here we demonstrate cure of HT1 by direct, in vivo administration of a therapeutic lentiviral vector targeting the expression of a human fumarylacetoacetate hydrolase (FAH) transgene in the porcine model of HT1. This therapy is well tolerated and provides stable long-term expression of FAH in pigs with HT1. Genomic integration displays a benign profile, with subsequent fibrosis and tumorigenicity gene expression patterns similar to wild-type animals as compared to NTBC-treated or diseased untreated animals. Indeed, the phenotypic and genomic data following in vivo lentiviral vector administration demonstrate comparative superiority over other therapies including ex vivo cell therapy and therefore support clinical application of this approach.

Efficient engraftment and viral transduction of human hepatocytes in an FRG rat liver humanization model

Humanized liver rodent models, in which the host liver parenchyma is repopulated by human hepatocytes, have been increasingly used for drug development and disease research. Unlike the leading humanized liver mouse model in which Fumarylacetoacetate Hydrolase (Fah), Recombination Activating Gene (Rag)-2 and Interleukin-2 Receptor Gamma (Il2rg) genes were inactivated simultaneously, generation of similar recipient rats has been challenging. Here, using Velocigene and 1-cell-embryo-targeting technologies, we generated a rat model deficient in Fah, Rag1/2 and Il2rg genes, similar to humanized liver mice. These rats were efficiently engrafted with Fah-expressing hepatocytes from rat, mouse and human. Humanized liver rats expressed human albumin and complement proteins in serum and showed a normal liver zonation pattern. Further, approaches were developed for gene delivery through viral transduction of human hepatocytes either in vivo, or in vitro prior to engraftment, providing a novel platform to study liver disease and hepatocyte-targeted therapies.

Direct chemical induction of hepatocyte-like cells with capacity for liver repopulation.

Cell fate can be directly reprogrammed from accessible cell types (e.g., fibroblasts) into functional cell types by exposure to small molecule stimuli. However, no chemical reprogramming method has been reported to date that successfully generates functional hepatocyte-like cells that can repopulate liver tissue, casting doubt over the feasibility of chemical reprogramming approaches to obtain desirable cell types for therapeutic applications. Here, through chemical induction of phenotypic plasticity, we provide a proof-of-concept demonstration of the direct chemical reprogramming of mouse fibroblasts into functional hepatocyte-like cells using exposure to small molecule cocktails in culture medium to successively stimulate endogenous expression of master transcription factors associated with hepatocyte development, such as hepatocyte nuclear factor 4a, nuclear receptor subfamily 1, group I, member 2, and nuclear receptor subfamily 1, group H, member 4. RNA sequencing analysis, metabolic assays, and in vivo physiological experiments show that chemically induced hepatocytes (CiHeps) exhibit comparable activity and function to primary hepatocytes, especially in liver repopulation to rescue liver failure in fumarylacetoacetate hydrolase -/- recombination activating gene 2 -/- interleukin 2 receptor, gamma chain -/- mice in vivo . Single-cell RNA-seq further revealed that gastrointestinal-like and keratinocyte-like cells were induced along with CiHeps, resembling the activation of an intestinal program within hepatic reprogramming as described in transgenic approaches. Our findings show that direct chemical reprogramming can generate hepatocyte-like cells with high-quality physiological properties, providing a paradigm for establishing hepatocyte identity in fibroblasts and demonstrating the potential for chemical reprogramming in organ/tissue repair and regeneration therapies.

The mitochondrial enzyme FAHD1 regulates complex II activity in breast cancer cells and is indispensable for basal BT-20 cells in vitro.

The mitochondrial enzyme fumarylacetoacetate hydrolase domain-containing protein 1 (FAHD1) was identified to be upregulated in breast cancer tissues. Here, we show that FAHD1 is indispensable for the survival of BT-20 cells, representing the basal breast cancer cell type. A lentiviral knock-down of FAHD1 in the breast cancer cell lines MCF-7 and BT-20 results in lower succinate dehydrogenase (complex II) activity. In luminal MCF-7 cells, this leads to reduced proliferation when cultured in medium containing only glutamine as the carbon source. Of note, both cell lines show attenuated protein levels of the enzyme glutaminase (GLS) which activates programmed cell death in BT-20. These findings demonstrate that FAHD1 is crucial for the functionality of complex II in breast cancer cells and acts on glutaminolysis in the mitochondria.

Phenylalanine suppresses cell death caused by loss of fumarylacetoacetate hydrolase in Arabidopsis

Fumarylacetoacetate hydrolase (FAH) catalyzes the final step of Tyrosine (Tyr) degradation pathway essential to animals and the deficiency of FAH causes an inborn lethal disease. In plants, a role of this pathway was unknown until we found that mutation of Short-day Sensitive Cell Death1 (SSCD1), encoding Arabidopsis FAH, results in cell death under short day. Phenylalanine (Phe) could be converted to Tyr and then degraded in both animals and plants. Phe ingestion in animals worsens the disease caused by FAH defect. However, in this study we found that Phe represses cell death caused by FAH defect in plants. Phe treatment promoted chlorophyll biosynthesis and suppressed the up-regulation of reactive oxygen species marker genes in the sscd1 mutant. Furthermore, the repression of sscd1 cell death by Phe could be reduced by α-aminooxi-β-phenylpropionic acid but increased by methyl jasmonate, which inhibits or activates Phe ammonia-lyase catalyzing the first step of phenylpropanoid pathway, respectively. In addition, we found that jasmonate signaling up-regulates Phe ammonia-lyase 1 and mediates the methyl jasmonate enhanced repression of sscd1 cell death by Phe. These results uncovered the relation between chlorophyll biosynthesis, phenylpropanoid pathway and jasmonate signaling in regulating the cell death resulting from loss of FAH in plants.

Patch grafting of organoids of stem/progenitors into solid organs can correct genetic-based disease states

Patch grafting, a novel strategy for transplantation of stem/progenitor organoids into porcine livers, has been found successful also for organoid transplantation into other normal or diseased solid organs in pigs and mice. Each organoid contained ∼100 cells comprised of biliary tree stem cells (BTSCs), co-hepato/pancreatic stem/progenitors, and partnered with early lineage stage mesenchymal cells (ELSMCs), angioblasts and precursors to endothelia and stellate cells. Patch grafting enabled transplantation into livers or pancreases of ≥108th (pigs) or ≥106th−7th (mice) organoids/patch. Graft conditions fostered expression of multiple matrix-metalloproteinases (MMPs), especially secretory isoforms, resulting in transient loss of the organ's matrix-dictated histological features, including organ capsules, and correlated with rapid integration within a week of organoids throughout the organs and without emboli or ectopic cell distribution. Secondarily, within another week, there was clearance of graft biomaterials, followed by muted expression of MMPs, restoration of matrix-dictated histology, and maturation of donor cells to functional adult fates.The ability of patch grafts of organoids to rescue hosts from genetic-based disease states was demonstrated with grafts of BTSC/ELSMC organoids on livers, able to rescue NRG/FAH-KO mice from type I tyrosinemia, a disease caused by absence of fumaryl acetoacetate hydrolase. With the same grafts, if on pancreas, they were able to rescue NRG/Akita mice from type I diabetes, caused by a mutation in the insulin 2 gene. The potential of patch grafting for cell therapies for solid organs now requires translational studies to enable its adaptation and uses for clinical programs.

MRNA-based therapy proves superior to the standard of care for treating hereditary tyrosinemia 1 in a mouse model

Hereditary tyrosinemia type 1 is an inborn error of amino acid metabolism characterized by deficiency of fumarylacetoacetate hydrolase (FAH). Only limited treatment options (e.g., oral nitisinone) are available. Patients must adhere to a strict diet and face a life-long risk of complications, including liver cancer and progressive neurocognitive decline. There is a tremendous need for innovative therapies that standardize metabolite levels and promise normal development. Here, we describe an mRNA-based therapeutic approach that rescues Fah-deficient mice, a well-established tyrosinemia model. Repeated intravenous or intramuscular administration of lipid nanoparticle-formulated human FAH mRNA resulted in FAH protein synthesis in deficient mouse livers, stabilized body weight, normalized pathologic increases in metabolites after nitisinone withdrawal, and prevented early death. Dose reduction and extended injection intervals proved therapeutically effective. These results provide proof of concept for an mRNA-based therapeutic approach to treating hereditary tyrosinemia type 1 that is superior to the standard of care.

Тирозинемія типу І у дитини: з досвіду гематолога

Tyrosinemia is a rare metabolic disease resulting from a metabolic disorder of amino acids, which can occur under the «masks» of various diseases, debut as a hemorrhagic syndrome in children of all age groups, hepatolienal syndrome, hypoglycemia, rickets-like disease, peripheral neuropathy. Clinical case. In our publication, we report on a girl at the age of 1 year 7 months who had recurrent nosebleeds, which led to a referral to a hematologist. Examination revealed hepatomegaly with impaired liver function (hypoproteinemia, long-term resistant hypoglycemia, coagulopathy) with the development of chronic liver failure, ascites and splenomegaly with signs of hypersplenism, ascites, and nephromegaly. Differential diagnostics was carried out between oncohematological process, myelodysplastic syndrome (MDS) and metabolic disease. Type 1 tyrosinemia (hereditary infantile tyrosinemia (HT-1)) was verified by a combination of clinical and biochemical, molecular genetic studies. Verification of the disease came from the spectrometry of amino acids, acylcarnitines, succinal acetates and molecular genetic studies. Molecular genetic studies in the INVITAE laboratory, USA revealed two pathogenic variants identified in the FAH gene c.1069G>T (p.Glu357*) and c.554-1G>T, which are associated with autosomal recessive tyrosinemia. The emphasis in the publication is on the differential diagnosis, the effectiveness of the treatment of this orphan disease. The method of pathogenetic therapy of HT-1 is described in detail, both with the use of the drug nitisinone (orphadin) registered in Ukraine, a special diet with a low content of phenylalanine / tyrosine, which have a pronounced positive clinical effect and prevent the formation of irreversible disabling disorders. We emphasize the need for early diagnosis of HT-1 and support the Ministry of Health of Ukraine in the initiative of routine neonatal screening for orphan diseases, which include HT-1, since timely treatment improves the quality of life in these patients. The research was carried out in accordance with the principles of the Helsinki declaration. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors. Key words: hepatosplenomegaly, nephromegaly, tyrosinemia type 1, children.