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Biochimica Et Biophysica Acta.... Aug 2024Peroxisome biogenesis disorders are caused by pathogenic variants in genes involved in biogenesis and maintenance of peroxisomes. However, mitochondria are also often...
Peroxisome biogenesis disorders are caused by pathogenic variants in genes involved in biogenesis and maintenance of peroxisomes. However, mitochondria are also often affected in these diseases. Peroxisomal membrane proteins, including PEX14, have been found to mislocalise to mitochondria in cells lacking peroxisomes. Recent studies indicated that this mislocalisation contributes to mitochondrial abnormalities in PEX3-deficient patient fibroblasts cells. Here, we studied whether mitochondrial morphology is also affected in PEX3-deficient HEK293 cells and whether PEX14 mislocalises to mitochondria in these cells. Using high-resolution imaging techniques, we show that although endogenous PEX14 mislocalises to mitochondria, mitochondrial morphology was normal in PEX3-KO HEK293 cells. However, we discovered that overexpression of tagged PEX14 in wild-type HEK293 cells resulted in its mitochondrial localisation, accompanied by altered mitochondrial morphology. Our data indicate that overexpression of tagged PEX14 alone directly or indirectly cause mitochondrial abnormalities in cells containing peroxisomes.
Topics: Humans; Mitochondria; Membrane Proteins; HEK293 Cells; Peroxisomes; Peroxins; Protein Transport; Lipoproteins; Repressor Proteins
PubMed: 38762172
DOI: 10.1016/j.bbamcr.2024.119754 -
Nature Communications May 2024The liver gene expression of the peroxisomal β-oxidation enzyme acyl-coenzyme A oxidase 1 (ACOX1), which catabolizes very long chain fatty acids (VLCFA), increases in...
The liver gene expression of the peroxisomal β-oxidation enzyme acyl-coenzyme A oxidase 1 (ACOX1), which catabolizes very long chain fatty acids (VLCFA), increases in the context of obesity, but how this pathway impacts systemic energy metabolism remains unknown. Here, we show that hepatic ACOX1-mediated β-oxidation regulates inter-organ communication involved in metabolic homeostasis. Liver-specific knockout of Acox1 (Acox1-LKO) protects mice from diet-induced obesity, adipose tissue inflammation, and systemic insulin resistance. Serum from Acox1-LKO mice promotes browning in cultured white adipocytes. Global serum lipidomics show increased circulating levels of several species of ω-3 VLCFAs (C24-C28) with previously uncharacterized physiological role that promote browning, mitochondrial biogenesis and Glut4 translocation through activation of the lipid sensor GPR120 in adipocytes. This work identifies hepatic peroxisomal β-oxidation as an important regulator of metabolic homeostasis and suggests that manipulation of ACOX1 or its substrates may treat obesity-associated metabolic disorders.
Topics: Animals; Liver; Mice, Knockout; Mice; Acyl-CoA Oxidase; Obesity; Male; Insulin Resistance; Mice, Inbred C57BL; Oxidation-Reduction; Lipid Metabolism; Adipose Tissue; Diet, High-Fat; Energy Metabolism; Fatty Acids; Receptors, G-Protein-Coupled
PubMed: 38760332
DOI: 10.1038/s41467-024-48471-2 -
BioRxiv : the Preprint Server For... Apr 2024Peroxisomal Biogenesis Disorders Zellweger Spectrum (PBD-ZSD) disorders are a group of autosomal recessive defects in peroxisome formation that produce a multi-systemic...
Peroxisomal Biogenesis Disorders Zellweger Spectrum (PBD-ZSD) disorders are a group of autosomal recessive defects in peroxisome formation that produce a multi-systemic disease presenting at birth or in childhood. Well documented clinical biomarkers such as elevated very long chain fatty acids (VLCFA) are key biochemical diagnostic findings in these conditions. Additional, secondary biochemical alterations such as elevated very long chain lysophosphatidylcholines are allowing newborn screening for peroxisomal disease. In addition, a more widespread impact on metabolism and lipids is increasingly being documented by metabolomic and lipidomic studies. Here we utilize models of and as well as human plasma from individuals with mutations. We identify phospholipid abnormalities in larvae and brain characterized by differences in the quantities of phosphatidylcholine (PC) and phosphatidylethanolamines (PE) with long chain lengths and reduced levels of intermediate chain lengths. For diacylglycerol (DAG) the precursor of PE and PC through the Kennedy pathway, the intermediate chain lengths are increased suggesting an imbalance between DAGs and PE and PC that suggests the two acyl chain pools are not in equilibrium. Altered acyl chain lengths are also observed in PE ceramides in the fly models. Interestingly, plasma from human subjects exhibit phospholipid alterations similar to the fly model. Moreover, human plasma shows reduced levels of sphingomyelin with 18 and 22 carbon lengths but normal levels of C24. Our results suggest that peroxisomal biogenesis defects alter shuttling of the acyl chains of multiple phospholipid and ceramide lipid classes, whereas DAG species with intermediate fatty acids are more abundant. These data suggest an imbalance between synthesis of PC and PE through the Kennedy pathway and remodeling of existing PC and PE through the Lands cycle. This imbalance is likely due to overabundance of very long and long acyl chains in PBD and a subsequent imbalance due to substrate channeling effects. Given the fundamental role of phospholipid and sphingolipids in nervous system functions, these observations suggest PBD-ZSD are diseases characterized by widespread cell membrane lipid abnormalities.
PubMed: 38746221
DOI: 10.1101/2024.04.26.591192 -
International Journal of Rheumatic... May 2024
Topics: Humans; Antibodies, Monoclonal, Humanized; Mevalonate Kinase Deficiency; Treatment Outcome; Female; Male; Time Factors; Adolescent; Child; Interleukin-1beta; Genetic Predisposition to Disease
PubMed: 38736276
DOI: 10.1111/1756-185X.15192 -
International Journal of Molecular... Apr 2024D-bifunctional protein deficiency (D-BPD) is a rare, autosomal recessive peroxisomal disorder that affects the breakdown of long-chain fatty acids. Patients with D-BPD... (Review)
Review
D-bifunctional protein deficiency (D-BPD) is a rare, autosomal recessive peroxisomal disorder that affects the breakdown of long-chain fatty acids. Patients with D-BPD typically present during the neonatal period with hypotonia, seizures, and facial dysmorphism, followed by severe developmental delay and early mortality. While some patients have survived past two years of age, the detectable enzyme activity in these rare cases was likely a contributing factor. We report a D-BPD case and comment on challenges faced in diagnosis based on a narrative literature review. An overview of Romania's first patient diagnosed with D-BPD is provided, including clinical presentation, imaging, biochemical, molecular data, and clinical course. Establishing a diagnosis can be challenging, as the clinical picture is often incomplete or similar to many other conditions. Our patient was diagnosed with type I D-BPD based on whole-exome sequencing (WES) results revealing a pathogenic frameshift variant of the gene, , , previously identified in another D-BPD patient. WES also identified a variant of the gene with unclear significance. We advocate for using molecular diagnosis in critically ill newborns and infants to improve care, reduce healthcare costs, and allow for familial counseling.
Topics: Humans; Peroxisomal Multifunctional Protein-2; Lipid Metabolism, Inborn Errors; Infant, Newborn; Infant; Male; Female; Exome Sequencing; Frameshift Mutation; 17-Hydroxysteroid Dehydrogenases; Resource-Limited Settings; Mitochondrial Myopathies; Cardiomyopathies; Nervous System Diseases; Mitochondrial Trifunctional Protein; Rhabdomyolysis
PubMed: 38732138
DOI: 10.3390/ijms25094924 -
Journal of Inherited Metabolic Disease May 2024Humans derive fatty acids (FA) from exogenous dietary sources and/or endogenous synthesis from acetyl-CoA, although some FA are solely derived from exogenous sources... (Review)
Review
Humans derive fatty acids (FA) from exogenous dietary sources and/or endogenous synthesis from acetyl-CoA, although some FA are solely derived from exogenous sources ("essential FA"). Once inside cells, FA may undergo a wide variety of different modifications, which include their activation to their corresponding CoA ester, the introduction of double bonds, the 2- and ω-hydroxylation and chain elongation, thereby generating a cellular FA pool which can be used for the synthesis of more complex lipids. The biological properties of complex lipids are very much determined by their molecular composition in terms of the FA incorporated into these lipid species. This immediately explains the existence of a range of genetic diseases in man, often with severe clinical consequences caused by variants in one of the many genes coding for enzymes responsible for these FA modifications. It is the purpose of this review to describe the current state of knowledge about FA homeostasis and the genetic diseases involved. This includes the disorders of FA activation, desaturation, 2- and ω-hydroxylation, and chain elongation, but also the disorders of FA breakdown, including disorders of peroxisomal and mitochondrial α- and β-oxidation.
PubMed: 38693715
DOI: 10.1002/jimd.12734 -
The Journal of Clinical Investigation Apr 2024Dicarboxylic fatty acids are generated in the liver and kidney in a minor pathway called fatty acid ω-oxidation. The effects of consuming dicarboxylic fatty acids as an...
Dicarboxylic fatty acids are generated in the liver and kidney in a minor pathway called fatty acid ω-oxidation. The effects of consuming dicarboxylic fatty acids as an alternative source of dietary fat have not been explored. Here, we fed dodecanedioic acid, a 12-carbon dicarboxylic (DC12), to mice at 20% of daily caloric intake for nine weeks. DC12 increased metabolic rate, reduced body fat, reduced liver fat, and improved glucose tolerance. We observed DC12-specific breakdown products in liver, kidney, muscle, heart, and brain, indicating that oral DC12 escaped first-pass liver metabolism and was utilized by many tissues. In tissues expressing the "a" isoform of acyl-CoA oxidase-1 (ACOX1), a key peroxisomal fatty acid oxidation enzyme, DC12 was chain shortened to the TCA cycle intermediate succinyl-CoA. In tissues with low peroxisomal fatty acid oxidation capacity, DC12 was oxidized by mitochondria. In vitro, DC12 was catabolized even by adipose tissue and was not stored intracellularly. We conclude that DC12 and other dicarboxylic acids may be useful for combatting obesity and for treating metabolic disorders.
PubMed: 38687608
DOI: 10.1172/JCI174186 -
Ophthalmic Genetics Apr 2024This cross-sectional study describes the ophthalmological and general phenotype of 10 patients from six different families with a comparatively mild form of Zellweger...
PURPOSE
This cross-sectional study describes the ophthalmological and general phenotype of 10 patients from six different families with a comparatively mild form of Zellweger spectrum disorder (ZSD), a rare peroxisomal disorder.
METHODS
Ophthalmological assessment included best-corrected visual acuity (BCVA), perimetry, microperimetry, ophthalmoscopy, fundus photography, spectral-domain optical coherence tomography (SD-OCT), and fundus autofluorescence (FAF) imaging. Medical records were reviewed for medical history and systemic manifestations of ZSD.
RESULTS
Nine patients were homozygous for c.2528 G > A (p.Gly843Asp) variants in and one patient was compound heterozygous for c.2528 G>A (p.Gly843Asp) and c.2097_2098insT (p.Ile700TyrfsTer42) in . Median age was 22.6 years (interquartile range (IQR): 15.9 - 29.9 years) at the most recent examination, with a median symptom duration of 22.1 years. Symptom onset was variable with presentations of hearing loss ( = 7) or nyctalopia/reduced visual acuity ( = 3) at a median age of 6 months (IQR: 1.9-8.3 months). BCVA (median of 0.8 logMAR; IQR: 0.6-0.9 logMAR) remained stable over 10.8 years and all patients were hyperopic. Fundus examination revealed a variable retinitis pigmentosa (RP)-like phenotype with rounded hyperpigmentations as most prominent feature in six out of nine patients. Electroretinography, visual field measurements, and microperimetry further established the RP-like phenotype. Multimodal imaging revealed significant intraretinal fluid cavities on SD-OCT and a remarkable pattern of hyperautofluorescent abnormalities on FAF in all patients.
CONCLUSION
This study highlights the ophthalmological phenotype resembling RP with moderate to severe visual impairment in patients with mild ZSD. These findings can aid ophthalmologists in diagnosing, counselling, and managing patients with mild ZSD.
PubMed: 38664000
DOI: 10.1080/13816810.2024.2330389 -
BMJ Case Reports Apr 2024Heimler Syndrome 2 (HS-2) is a rare, autosomal recessive mild form of a peroxisomal biogenesis disorder. Though knowledge regarding the disorder is limited, emerging...
Heimler Syndrome 2 (HS-2) is a rare, autosomal recessive mild form of a peroxisomal biogenesis disorder. Though knowledge regarding the disorder is limited, emerging research has found that sensorineural hearing loss, occasional or late onset pigmentation, amelogenesis imperfecta and nail abnormalities are clinical characteristics representative of HS-2.A school-aged male presented to the dental department with a chief complaint of a lack of enamel on multiple teeth. The patient's medical history was significant for patent ductus arteriosus, bilateral sensorineural hearing loss and biallelic mutation of the PEX6 gene. The clinical exam revealed dental crowding, hypoplasia, hypo-calcification of multiple teeth and enlarged pulp chambers of maxillary molars. This case report details the clinical findings associated with HS-2, the comprehensive dental treatment to be rendered to the patient, and critical information to paediatric dentists and general dentists so that they can make proper referrals to medical specialties.
Topics: Humans; Male; Child; Hearing Loss, Sensorineural
PubMed: 38663901
DOI: 10.1136/bcr-2023-257354