Biology subjects

Barnhoorn, S.

Publications and source records attributed to Barnhoorn, S..

4 recordsLinked to original sources

bioRxiv2023

Orthogonal analysis of mitochondrial function in Parkinson's disease patients

The etiopathology of Parkinsons disease has been associated with mitochondrial defects at genetic, laboratory, epidemiological, and clinical level. These converging lines of evidence suggest that mitochondrial defects are systemic and causative factors in the pathophysiology of PD, rather than being mere correlates. Understanding mitochondrial biology in PD at granular level is therefore crucial from both basic science and translational perspectives. In a recent study, we investigated mitochondrial alterations in fibroblasts obtained from PD patients assessing mitochondrial function in relation to clinical measures. Our findings demonstrated that the magnitude of mitochondrial alterations parallels disease severity. In this study, we extend these investigations to blood cells and dopamine neurons derived from induced pluripotent stem cells reprogrammed from PD patients. To overcome the inherent metabolic heterogeneity of blood cells, we focused our analyses on metabolically homogeneous, accessible, and expandable erythroblasts. Our results confirm the presence of mitochondrial anomalies in erythroblasts and induced dopamine neurons. Consistent with our previous findings in fibroblasts, we observed that mitochondrial alterations are reversible, as evidenced by enhanced mitochondrial respiration when PD erythroblasts were cultured in a galactose medium that restricts glycolysis. This observation indicates that suppression of mitochondrial respiration may constitute a protective, adaptive response in PD pathogenesis. Notably, this effect was not observed in induced dopamine neurons, suggesting their distinct bioenergetic behavior. In summary, we provide additional evidence for the involvement of mitochondria in the disease process by demonstrating mitochondrial abnormalities in additional cell types relevant to PD. These findings contribute to our understanding of PD pathophysiology and may have implications for the development of novel biomarkers and therapeutic strategies.

neuroscience↗

bioRxiv2021

Generation, characterization and drug sensitivities of twelve patient-derived IDH1 mutant glioma cell cultures

BackgroundMutations of the isocitrate dehydrogenase (IDH) gene occur in over 80% of low-grade gliomas and secondary glioblastomas. Despite considerable efforts, endogenous in vitro IDH-mutated glioma models remain scarce. Availability of these models is key for the development of new therapeutic interventions. MethodsCell cultures were established from fresh tumor material and expanded in serum-free culture media. D-2-Hydroxyglutarate levels were determined by mass-spectrometry. Genomic and transcriptomic profiling were carried out on the Illumina Novaseq platform, methylation profiling was performed with the Infinium MethylationEpic BeadChip array. Mitochondrial respiration was measured with the Seahorse XF24 Analyzer. Drug screens were performed with an NIH FDA-approved anti-cancer drug set and two IDH-mutant specific inhibitors. ResultsA set of twelve patient-derived IDHmt cell cultures was established. We confirmed high concordance in driver mutations, copy number and methylation profiles between the tumors and derived cultures. Homozygous deletion of CDKN2A/B was observed in all cultures. IDH-mutant cultures had lower mitochondrial reserve capacity. IDH-mutant specific inhibitors did not affect cell viability or global gene expression. Screening of 107 FDA-approved anti-cancer drugs identified nine compounds with potent activity against IDHmt gliomas, including three compounds with favorable pharmacokinetic characteristics for CNS penetration: teniposide, omacetaxine mepesuccinate, and marizomib. ConclusionsOur twelve IDH-mutant cell cultures show high similarity to the parental tissues and offer a unique tool to study the biology and drug sensitivities of high-grade IDHmt gliomas in vitro. Our drug screening studies reveal lack of sensitivity to IDHmt inhibitors, but sensitivity to a set of nine available anti-cancer agents. Key pointsO_LIIDHmt glioma cultures closely resemble their parental tumors C_LIO_LIMicroscopic monitoring of early passages and colony isolation increases IDH1mt culture success C_LIO_LIDrug screening identified nine candidate repurposed drugs for IDHmt glioma C_LI Importance of the studyIDH-mutations are highly prevalent in low grade and secondary high-grade gliomas. Despite this high frequency however, very few in vitro models have been reported for IDH-mutated gliomas. In this manuscript we describe and characterize in detail twelve primary cultures from IDH-mutant astrocytomas. We show that these cultures retain most of the genetic, epigenetic and metabolic features of their respective parental tumors. Because of these similarities, these independent model systems will not only help understand the molecular defects driven by the mutation, but are also vital to identify means to target these tumors. Screening of 107 FDA-approved anti-cancer agents on these cultures identified a set of highly effective agents that may offer candidates for either systemic or assisted delivery treatment of this tumor subtype.

cancer biology↗

bioRxiv2020

TWIST1 controls cellular senescence and energy metabolism in mesenchymal stem cells

Mesenchymal stem cells (MSC) are promising cells for regenerative medicine therapies, because they can differentiate towards multiple cell lineages. However, heterogeneity in differentiation capacity is one of the main drawbacks that limit their use clinically. Differences in the occurrence of cellular senescence and in the expression of the senescence associated secretory phenotype (SASP) in MSC populations contribute to their heterogeneity. Here, we show the involvement of TWIST1 expression in the regulation of MSC senescence, demonstrating that silencing of TWIST1 in MSCs increased the occurrence of senescence. These senescent MSCs had a SASP that was different from irradiation-induced senescent MSCs. In addition, metabolic evaluation performed by the Seahorse XF apparatus showed that both TWIST1 silencing-induced and irradiation-induced senescent MSCs had a higher oxygen consumption compared to control MSCs, while TWIST1 silencing-induced senescent MSCs had a low extracellular acidification rate compared to the irradiation-induced senescent MSCs. Overall, our data indicate how TWIST1 regulation influences senescence in human MSCs and that TWIST1 silencing-induced senescence is characterized by a specific expression of the SASP and the metabolic state.

cell biology↗

bioRxiv2019

SLC2A knockout mice deficient in ascorbic acid synthesis recapitulate aspects of arterial tortuosity syndrome and display mitochondrial respiration defects

Arterial tortuosity syndrome (ATS) is a recessively inherited connective tissue disorder, mainly characterized by tortuosity and aneurysm formation of the major arteries. ATS is caused by loss-of-function mutations in SLC2A10, encoding the facilitative glucose transporter GLUT10. Former studies implicate GLUT10 in transport of dehydroascorbic acid, the oxidized form of ascorbic acid (AA). Mouse models carrying homozygous Slc2a10 missense mutations do not recapitulate the human phenotype. Since mice, in contrast to humans, are able to intracellularly synthesize AA, we generated a novel ATS mouse model, deficient for Slc2a10 as well as Gulo, which encodes for L-gulonolactone oxidase, an enzyme catalyzing the final step in AA biosynthesis in rodents. Gulo;Slc2a10 knock-out mice show mild phenotypic anomalies, which were absent in single knock-out controls. While Gulo;Slc2a10 knock-out mice do not fully phenocopy human ATS, histological and immunocytochemical analysis revealed compromised extracellular matrix formation. TGF{beta} signaling remained unaltered, while mitochondrial function was compromised in smooth muscle cells derived from Gulo;Slc2a10 knock-out mice. Altogether, our data add evidence that ATS is an ascorbate compartmentalization disorder, but additional factors underlying the observed phenotype in humans remain to be determined.

genetics↗