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- Wiessner, M., et al.
(author)
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Biallelic variants in HPDL cause pure and complicated hereditary spastic paraplegia
- 2021
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In: Brain : a journal of neurology. - : Oxford University Press (OUP). - 0006-8950 .- 1460-2156. ; 144:5, s. 1422-1434
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Journal article (peer-reviewed)abstract
- Human 4-hydroxyphenylpyruvate dioxygenase-like (HPDL) is a putative iron-containing non-heme oxygenase of unknown specificity and biological significance. We report 25 families containing 34 individuals with neurological disease associated with biallelic HPDL variants. Phenotypes ranged from juvenile-onset pure hereditary spastic paraplegia to infantile-onset spasticity and global developmental delays, sometimes complicated by episodes of neurological and respiratory decompensation. Variants included bona fide pathogenic truncating changes, although most were missense substitutions. Functionality of variants could not be determined directly as the enzymatic specificity of HPDL is unknown; however, when HPDL missense substitutions were introduced into 4-hydroxyphenylpyruvate dioxygenase (HPPD, an HPDL orthologue), they impaired the ability of HPPD to convert 4-hydroxyphenylpyruvate into homogentisate. Moreover, three additional sets of experiments provided evidence for a role of HPDL in the nervous system and further supported its link to neurological disease: (i) HPDL was expressed in the nervous system and expression increased during neural differentiation; (ii) knockdown of zebrafish hpdl led to abnormal motor behaviour, replicating aspects of the human disease; and (iii) HPDL localized to mitochondria, consistent with mitochondrial disease that is often associated with neurological manifestations. Our findings suggest that biallelic HPDL variants cause a syndrome varying from juvenile-onset pure hereditary spastic paraplegia to infantile-onset spastic tetraplegia associated with global developmental delays. © 2021 The Author(s).
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- Ma, Haixia, et al.
(author)
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The transcription factor Foxp1 regulates aerobic glycolysis in adipocytes and myocytes
- 2023
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In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 299:6
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Journal article (peer-reviewed)abstract
- In recent years, lactate has been recognized as an important circulating energy substrate rather than only a dead-end metabolic waste product generated during glucose oxidation at low levels of oxygen. The term "aerobic glycolysis" has been coined to denote increased glucose uptake and lactate pro-duction despite normal oxygen levels and functional mito-chondria. Hence, in "aerobic glycolysis," lactate production is a metabolic choice, whereas in "anaerobic glycolysis," it is a metabolic necessity based on inadequate levels of oxygen. Interestingly, lactate can be taken up by cells and oxidized to pyruvate and thus constitutes a source of pyruvate that is in-dependent of insulin. Here, we show that the transcription factor Foxp1 regulates glucose uptake and lactate production in adipocytes and myocytes. Overexpression of Foxp1 leads to increased glucose uptake and lactate production. In addition, protein levels of several enzymes in the glycolytic pathway are upregulated, such as hexokinase 2, phosphofructokinase, aldolase, and lactate dehydrogenase. Using chromatin immu-noprecipitation and real-time quantitative PCR assays, we demonstrate that Foxp1 directly interacts with promoter consensus cis-elements that regulate expression of several of these target genes. Conversely, knockdown of Foxp1 suppresses these enzyme levels and lowers glucose uptake and lactate production. Moreover, mice with a targeted deletion of Foxp1 in muscle display systemic glucose intolerance with decreased muscle glucose uptake. In primary human adipocytes with induced expression of Foxp1, we find increased glycolysis and glycolytic capacity. Our results indicate Foxp1 may play an important role as a regulator of aerobic glycolysis in adipose tissue and muscle.
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- Bartesaghi, S, et al.
(author)
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Inhibition of oxidative metabolism leads to p53 genetic inactivation and transformation in neural stem cells
- 2015
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 112:4, s. 1059-1064
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Journal article (peer-reviewed)abstract
- Brain cancer is one of the deadliest human tumors and is characterized by several genetic changes leading to impairment of tumor suppressive pathways and oncogene activation. These genetic alterations promote subsequent molecular changes, including modifications of cellular metabolism, which are believed to contribute to cancer pathogenesis. Conversely, the role of metabolic changes in regulation of genomic stability in brain cancer has not been investigated. Our work shows that alterations of mitochondrial metabolism promote genetic loss of the p53 tumor suppressor and transformation via a mechanism involving reactive oxygen species. Overall, our findings suggest a causative link between metabolic alterations and loss of tumor suppressive control in the central nervous system, with implications for our understanding of brain cancer pathogenesis.
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