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Methods in Molecular Biology (Clifton,... 2022Abnormal accumulation of very-long-chain fatty acids (VLCFAs), defined as molecules with greater than 22 carbons, and branched-chain fatty acids, pristanic and phytanic...
Abnormal accumulation of very-long-chain fatty acids (VLCFAs), defined as molecules with greater than 22 carbons, and branched-chain fatty acids, pristanic and phytanic acids, is characteristic of inborn errors of peroxisomal biogenesis or function. X-linked adrenoleukodystrophy, Zellweger spectrum disorders, rhizomelic chondrodysplasia punctata, and Refsum syndrome can be diagnosed biochemically by quantitation of these metabolites in plasma. Ratios of C24/C22 and C26/C22 can help improve detection of X-linked adrenoleukodystrophy. Analysis using gas-chromatography mass spectrometry (GC/MS) after acid/base hydrolysis, organic solvent extraction, and derivatization is an established method for clinical diagnostics. This chapter describes detailed steps to process plasma samples for GC/MS analysis.
Topics: Adrenoleukodystrophy; Fatty Acids; Gas Chromatography-Mass Spectrometry; Humans; Phytanic Acid; Solvents
PubMed: 36127617
DOI: 10.1007/978-1-0716-2565-1_45 -
Cells Jun 2022Zellweger spectrum disorder (ZSD) is a rare, debilitating genetic disorder of peroxisome biogenesis that affects multiple organ systems and presents with broad clinical... (Meta-Analysis)
Meta-Analysis Review
Zellweger spectrum disorder (ZSD) is a rare, debilitating genetic disorder of peroxisome biogenesis that affects multiple organ systems and presents with broad clinical heterogeneity. Although severe, intermediate, and mild forms of ZSD have been described, these designations are often arbitrary, presenting difficulty in understanding individual prognosis and treatment effectiveness. The purpose of this study is to conduct a scoping review and meta-analysis of existing literature and a medical chart review to determine if characterization of clinical findings can predict severity in ZSD. Our PubMed search for articles describing severity, clinical findings, and survival in ZSD resulted in 107 studies (representing 307 patients) that were included in the review and meta-analysis. We also collected and analyzed these same parameters from medical records of 136 ZSD individuals from our natural history study. Common clinical findings that were significantly different across severity categories included seizures, hypotonia, reduced mobility, feeding difficulties, renal cysts, adrenal insufficiency, hearing and vision loss, and a shortened lifespan. Our primary data analysis also revealed significant differences across severity categories in failure to thrive, gastroesophageal reflux, bone fractures, global developmental delay, verbal communication difficulties, and cardiac abnormalities. Univariable multinomial logistic modeling analysis of clinical findings and very long chain fatty acid (VLCFA) hexacosanoic acid (C26:0) levels showed that the number of clinical findings present among seizures, abnormal EEG, renal cysts, and cardiac abnormalities, as well as plasma C26:0 fatty acid levels could differentiate severity categories. We report the largest characterization of clinical findings in relation to overall disease severity in ZSD. This information will be useful in determining appropriate outcomes for specific subjects in clinical trials for ZSD.
Topics: Fatty Acids; Humans; Kidney Diseases, Cystic; Membrane Proteins; Seizures; Zellweger Syndrome
PubMed: 35741019
DOI: 10.3390/cells11121891 -
Mitochondrial changes and oxidative stress in a mouse model of Zellweger syndrome neuropathogenesis.Neuroscience Oct 2016Zellweger syndrome (ZS) is a peroxisome biogenesis disorder that involves significant neuropathology, the molecular basis of which is still poorly understood. Using a...
Zellweger syndrome (ZS) is a peroxisome biogenesis disorder that involves significant neuropathology, the molecular basis of which is still poorly understood. Using a mouse model of ZS with brain-restricted deficiency of the peroxisome biogenesis protein PEX13, we demonstrated an expanded and morphologically modified brain mitochondrial population. Cultured fibroblasts from PEX13-deficient mouse embryo displayed similar changes, as well as increased levels of mitochondrial superoxide and membrane depolarization; this phenotype was rescued by antioxidant treatment. Significant oxidative damage to neurons in brain was indicated by products of lipid and DNA oxidation. Similar overall changes were observed for glial cells. In toto, these findings suggest that mitochondrial oxidative stress and aberrant mitochondrial dynamics are associated with the neuropathology arising from PEX13 deficiency.
Topics: Animals; Blotting, Western; Brain; Cells, Cultured; Disease Models, Animal; Fibroblasts; Fluorescent Antibody Technique; Glial Fibrillary Acidic Protein; Membrane Proteins; Mice, Inbred C57BL; Mice, Knockout; Microscopy, Fluorescence; Mitochondria; Neuroglia; Oxidative Stress; Superoxide Dismutase; Tryptophan Hydroxylase; Zellweger Syndrome
PubMed: 27514574
DOI: 10.1016/j.neuroscience.2016.08.001 -
Frontiers in Cell and Developmental... 2020Ketohexokinase (KHK) is the first and rate-limiting enzyme of fructose metabolism. Expression of the two alternatively spliced KHK isoforms, KHK-A and KHK-C, is...
Ketohexokinase (KHK) is the first and rate-limiting enzyme of fructose metabolism. Expression of the two alternatively spliced KHK isoforms, KHK-A and KHK-C, is tissue-specific and KHK-C is predominantly expressed in liver, kidney and intestine and responsible for the fructose-catabolizing function. While KHK isoform choice has been linked to the development of disorders such as obesity, diabetes, cardiovascular disease and cancer, little is known about the regulation of total KHK expression. In the present study, we investigated how hypoxic signaling influences fructose metabolism in the liver. Hypoxia or von Hippel-Lindau (VHL) tumor suppressor loss leads to the stabilization of hypoxia-inducible factors alpha (HIF-1α and HIF-2α) and the activation of their signaling to mediate adaptive responses. By studying liver-specific , /, and / knockout mice, we found that KHK expression is suppressed by HIF-2α (encoded by ) but not by HIF-1α signaling on mRNA and protein levels. Reduced KHK levels were accompanied by downregulation of aldolase B (ALDOB) in the livers of and knockout mice, further indicating inhibited fructose metabolism. HIF-1α and HIF-2α have both overlapping and distinct target genes but are differentially regulated depending on the cell type and physiologic or pathologic conditions. HIF-2α activation augments peroxisome degradation in mammalian cells by pexophagy and thereby changes lipid composition reminiscent of peroxisomal disorders. We further demonstrated that fructose metabolism is negatively regulated by peroxisome-deficiency in a knockout Zellweger mouse model, which lacks functional peroxisomes and is characterized by widespread metabolic dysfunction. Repression of fructolytic genes in knockout mice appeared to be independent of PPARα signaling and nutritional status. Interestingly, our results demonstrate that both HIF-2α and peroxisome-deficiency result in downregulation of independent of splicing as both isoforms, as well as , are significantly downregulated. Hence, our study offers new and unexpected insights into the general regulation of KHK, and therefore fructolysis. We revealed a novel regulatory function of HIF-2α, suggesting that HIF-1α and HIF-2α have tissue-specific opposing roles in the regulation of expression, isoform choice and fructolysis. In addition, we discovered a previously unknown function of peroxisomes in the regulation of fructose metabolism.
PubMed: 32733884
DOI: 10.3389/fcell.2020.00566 -
Biochemical and Biophysical Research... Mar 2021Peroxisomes play an essential role in cellular homeostasis by regulating lipid metabolism and the conversion of reactive oxygen species (ROS). Several peroxisomal...
Peroxisomes play an essential role in cellular homeostasis by regulating lipid metabolism and the conversion of reactive oxygen species (ROS). Several peroxisomal proteins, known as peroxins (PEXs), control peroxisome biogenesis and degradation. Various mutations in the PEX genes are genetic causes for the development of inheritable peroxisomal-biogenesis disorders, such as Zellweger syndrome. Among the peroxins, PEX1 defects are the most common mutations in Zellweger syndrome. PEX1 is an AAA-ATPase that regulates the recycling of PEX5, which is essential for importing peroxisome matrix proteins. However, the post-transcriptional regulation of PEX1 is largely unknown. Here, we showed that heterogeneous nuclear ribonucleoprotein A1 (HNRNPA1) controls PEX1 expression. In addition, we found that depletion of HNRNPA1 induces autophagic degradation of peroxisome, which is blocked in ATG5-knockout cells. In addition, depletion of HNRNPA1 increased peroxisomal ROS levels. Inhibition of the generation of peroxisomal ROS by treatment with NAC significantly suppressed pexophagy in HNRNPA1-deficient cells. Taken together, our results suggest that depletion of HNRNPA1 increases peroxisomal ROS and pexophagy by downregulating PEX1 expression.
Topics: ATPases Associated with Diverse Cellular Activities; Autophagy-Related Protein 5; Cells, Cultured; Down-Regulation; Gene Knockout Techniques; HCT116 Cells; HeLa Cells; Heterogeneous Nuclear Ribonucleoprotein A1; Humans; Macroautophagy; Membrane Proteins; Peroxisomes; RNA Processing, Post-Transcriptional; RNA, Messenger; Reactive Oxygen Species; Zellweger Syndrome
PubMed: 33545634
DOI: 10.1016/j.bbrc.2021.01.083 -
BMJ Case Reports Apr 2016Peroxisome biogenesis disorders are related to a spectrum of genetic diseases that range from severe Zellweger syndrome to milder infantile Refsum disease. Zellweger...
Peroxisome biogenesis disorders are related to a spectrum of genetic diseases that range from severe Zellweger syndrome to milder infantile Refsum disease. Zellweger syndrome is characterised by dysmorphic features, severe hypotonia, seizures, failure to thrive, liver dysfunction and skeletal defects. Increased levels of very long chain fatty acids are the biochemical hallmark and the most common mutations found in the PEX1 gene. We report an unusual presentation of Zellweger syndrome in a 2-month-old female infant with severe malnutrition, opportunistic infections, lymphopaenia and a small thymic shadow on chest radiography. With this clinical picture, an initial hypothesis of primary immunodeficiency was considered. It was later confirmed to not be the case. On follow-up, global developmental delay, bilateral optic nerve atrophy and moderate bilateral sensorineural deafness grade II were documented. There were no further infectious complications and we concluded malnutrition was the cause of the infant's immunocompromised state.
Topics: Female; Humans; Immunocompromised Host; Infant; Infant Nutrition Disorders; Lymphopenia; Opportunistic Infections; Zellweger Syndrome
PubMed: 27090541
DOI: 10.1136/bcr-2015-214283 -
Molecular and Cellular Neurosciences Apr 2018Zellweger syndrome (ZS), a neonatal lethal disorder arising from defective peroxisome biogenesis, features profound neuroanatomical abnormalities and brain dysfunction....
Zellweger syndrome (ZS), a neonatal lethal disorder arising from defective peroxisome biogenesis, features profound neuroanatomical abnormalities and brain dysfunction. Here we used mice with brain-restricted inactivation of the peroxisome biogenesis gene PEX13 to model the pathophysiological features of ZS, and determine the impact of peroxisome dysfunction on neurogenesis and cell maturation in ZS. In the embryonic and postnatal PEX13 mutant brain, we demonstrate key regions with altered brain anatomy, including enlarged lateral ventricles and aberrant cortical, hippocampal and hypothalamic organization. To characterize the underlying mechanisms, we show a significant reduction in proliferation, migration, differentiation, and maturation of neural progenitors in embryonic E12.5 through to P3 animals. An increasing reactive gliosis in the PEX13 mutant brain started at E14.5 in association with the pathology. Together with impaired neurogenesis and associated gliosis, our data demonstrate increased cell death contributing to the hallmark brain anatomy of ZS. We provide unique data where impaired neurogenesis and migration are shown as critical events underlying the neuropathology and altered brain function of mice with peroxisome deficiency.
Topics: Animals; Brain; Cell Differentiation; Disease Models, Animal; Fibroblasts; Gliosis; Membrane Proteins; Mice; Mutation; Neurogenesis; Peroxisomes; Zellweger Syndrome
PubMed: 29187321
DOI: 10.1016/j.mcn.2017.11.015 -
Metabolites May 2021Peroxisomes are central hubs for cell metabolism and their dysfunction is linked to devastating human disorders, such as peroxisomal biogenesis disorders and single...
Peroxisomes are central hubs for cell metabolism and their dysfunction is linked to devastating human disorders, such as peroxisomal biogenesis disorders and single peroxisomal enzyme/protein deficiencies. For decades, biochemical diagnostics have been carried out using classical markers such as very long-chain fatty acids (VLCFA), which can be inconspicuous in milder and atypical cases. Holistic metabolomics studies revealed several potentially new biomarkers for peroxisomal disorders for advanced laboratory diagnostics including atypical cases. However, establishing these new markers is a major challenge in routine diagnostic laboratories. We therefore investigated whether the commercially available AbsoluteIDQ p180 kit (Biocrates Lifesciences), which utilizes flow injection and liquid chromatography mass spectrometry, may be used to reproduce some key results from previous global metabolomics studies. We applied it to serum samples from patients with mutations in peroxisomal target genes , , and the gene. Here we found various changes in sphingomyelins and lysophosphatidylcholines. In conclusion, this kit can be used to carry out extended diagnostics for peroxisomal disorders in routine laboratories, even without access to a metabolomics unit.
PubMed: 34072483
DOI: 10.3390/metabo11060347 -
Scientific Reports May 2018Peroxisomes are ubiquitous cell organelles involved in many metabolic and signaling functions. Their assembly requires peroxins, encoded by PEX genes. Mutations in PEX...
Peroxisomes are ubiquitous cell organelles involved in many metabolic and signaling functions. Their assembly requires peroxins, encoded by PEX genes. Mutations in PEX genes are the cause of Zellweger Syndrome spectrum (ZSS), a heterogeneous group of peroxisomal biogenesis disorders (PBD). The size and morphological features of peroxisomes are below the diffraction limit of light, which makes them attractive for super-resolution imaging. We applied Stimulated Emission Depletion (STED) microscopy to study the morphology of human peroxisomes and peroxisomal protein localization in human controls and ZSS patients. We defined the peroxisome morphology in healthy skin fibroblasts and the sub-diffraction phenotype of residual peroxisomal structures ('ghosts') in ZSS patients that revealed a relation between mutation severity and clinical phenotype. Further, we investigated the 70 kDa peroxisomal membrane protein (PMP70) abundance in relationship to the ZSS sub-diffraction phenotype. This work improves the morphological definition of peroxisomes. It expands current knowledge about peroxisome biogenesis and ZSS pathoethiology to the sub-diffraction phenotype including key peroxins and the characteristics of ghost peroxisomes.
Topics: ATP-Binding Cassette Transporters; Fibroblasts; Humans; PHEX Phosphate Regulating Neutral Endopeptidase; Peroxisomes; Zellweger Syndrome
PubMed: 29773809
DOI: 10.1038/s41598-018-24119-2 -
Blenderized Tube Feeding: Health Outcomes and Review of Homemade and Commercially Prepared Products.Nutrition in Clinical Practice :... Jun 2020The popularity of homemade blenderized tube feeding (HBTF) continues to increase among enteral nutrition (EN) consumers and healthcare providers alike, citing improved... (Review)
Review
The popularity of homemade blenderized tube feeding (HBTF) continues to increase among enteral nutrition (EN) consumers and healthcare providers alike, citing improved feeding tolerance over standard commercial enteral formulas, among other health outcomes. Within the past 5-10 years, there has been a surge in the development of commercial blenderized tube feeding (CBTF) products. CBTF products promote similar benefits from whole foods like those used in HBTF while being a nutritionally-consistent, easy to use, and shelf-stable option for EN consumers. Research is improving but is still limited for HBTF and virtually nonexistent for CBTF products. This review aims to summarize current health outcomes of HBTF, compare HBTF with CBTF, evaluate CBTF products, and provide considerations for future research and practices.
Topics: Humans; Infant; Male; Attitude of Health Personnel; Costs and Cost Analysis; Enteral Nutrition; Food Handling; Food Storage; Food, Formulated; Gastrointestinal Microbiome; History, 20th Century; History, 21st Century; Nutritive Value; Treatment Outcome; Zellweger Syndrome
PubMed: 32362020
DOI: 10.1002/ncp.10493