Biology subjects

Cascalho, A.

Publications and source records attributed to Cascalho, A..

3 recordsLinked to original sources

bioRxiv2024

Loss of the lysosomal lipid flippase ATP10B leads to progressive dopaminergic neurodegeneration and Parkinsonian motor deficits

BackgroundATP10B, a transmembrane lipid flippase located in late endosomes and lysosomes, facilitates the export of glucosylceramide and phosphatidylcholine by coupling this process to ATP hydrolysis. Recently, loss-of-function mutations in the ATP10B gene have been identified in Parkinsons disease patients, pointing to ATP10B as a candidate genetic risk factor. Previous studies have shown compromised lysosomal functionality upon ATP10B knockdown in human cell lines and primary cortical neurons. However, its role in vivo and specifically in the nigrostriatal dopaminergic system remains poorly understood. MethodsTo investigate the role ATP10B in PD neuropathology, we induced ATP10B knockdown specifically in substantia nigra pars compacta neurons of rats using viral vector technology. Two different microRNA-based shRNA constructs targeting distinct regions of the ATP10B mRNA were used to cross-validate the findings. Behavioral evaluation, dopamine transporter 18F-FE-PE2I positron emission tomography imaging and neuropathological examination of the nigrostriatal pathway at one year post-injection were conducted. Additionally, midbrain neuronal cultures derived from ATP10B knock-out human induced pluripotent stem cells clones were used to study the impact of ATP10B loss in dopaminergic neurons in a more translational model. ResultsATP10B knockdown in rat brain induced Parkinsonian motor deficits, and longitudinal striatal dopamine transporter 18F-FE-PE2I PET imaging revealed a progressive decrease in binding potential. Immunohistochemical analysis conducted one year post-injection confirmed the loss of dopaminergic terminals in the striatum, alongside a loss of dopaminergic neurons in the substantia nigra pars compacta. The expression of LAMP1, LAMP2a, cathepsin B and glucocerebrosidase was studied by immunofluorescence in the surviving dopaminergic neurons. A decrease in lysosomal numbers and an increase in lysosomal volume were observed more consistently in one of the knockdown constructs. The vulnerability of dopaminergic neurons to ATP10B loss-of-function was also observed in midbrain neuronal cultures derived from ATP10B knock-out human induced pluripotent stem cells clones, which showed a significant reduction in TH-positive neurons. ConclusionTaken together, our findings demonstrate that ATP10B depletion detrimentally impacts the viability of dopaminergic neurons both in vivo and in vitro. Moreover, a broader impact on the functionality of the nigrostriatal pathway was evidenced as rats with ATP10B knockdown exhibited motor impairments similar to those observed in PD patients.

neuroscience↗

bioRxiv2020

Lipid metabolic stress in development defines which genetically-susceptible DYT-TOR1A mice develop disease

There has been enormous progress defining the genetic landscape of disease. However, genotypes rarely fully predict neurological phenotypes, and we rarely understand why. TOR1A +/{Delta}gag that causes dystonia with ~30% penetrance is a classic case. Here we show, in inbred mice, that +/{Delta}gag affects embryonic brain lipid metabolism with sex-skewed reduced penetrance. Penetrance is affected by environmental context, including maternal diet. The lipid metabolic defect resolves during post-natal development. Nevertheless, we discover dystonia-like symptoms in ~30% of juvenile female Tor1a+/{Delta}gag mice, and prevent these symptoms by genetically suppressing abnormal lipid metabolism. We conclude that Tor1a+/{Delta}gag embryos poorly buffer metabolic stress in utero, resulting in a period of abnormal metabolism that hardwires the brain for dystonia in later life. The data show unexpected and profound impacts of sex, and thus highlight the importance of examining male and female animal models of disease. Significance StatementThe genetic landscape of neurological disease is relatively well mapped. However, we typically cannot explain why some mutations only cause disease in a subset of individuals. A classic case is DYT-TOR1A dystonia that only develops in 30% of TOR1A+/{Delta}gag carriers. We now find that ~30% of inbred female Tor1a+/{Delta}gag mice develop abnormal brain lipid metabolism as embryos, while males are spared. The percentage is affected by maternal diet. Further, this period of abnormal lipid metabolism causes dystonia-like symptoms in juvenile mice. These data show how an environmentally-sensitive event of development defines which genetically-susceptible individuals develop disease in later life. They also highlight the importance of examining male and female animal models of disease.

neuroscience↗

bioRxiv2019

Inhibition of Lipin lipid phosphatase hyperactivity rescues TorsinA neurological disease

TOR1A/TorsinA mutations cause poorly explained neurological diseases. A dominantly inherited mutation causes isolated dystonia, while biallelic mutations cause a recessive infant-onset syndrome with cases of lethality. Here we report an unexpected connection between lipid metabolism and these diseases. Lipin phosphatidic acid phosphatase activity was abnormally regulated in TorsinA dystonia patient cells, and in the brains of three different TorsinA disease model mice. Lipin activity was causative to symptoms given that lowering Lipin1 in vivo strongly intervened against lethality in disease mice. Furthermore, Lipin hyperactivity caused cell death in vitro, and Lipin1 deficiency suppressed neurodegeneration in vivo. In addition, it protected the striatal cholinergic interneurons that are implicated in TorsinA movement disorders, and concomitantly suppressed abnormal motor behaviors of TorsinA mice. These data establish the central role of Lipin lipid enzyme hyperactivity in TorsinA disease and show that Lipin inhibition is a therapeutic target for these incurable conditions.\n\nOne Sentence SummaryLipin inhibition rescues TorsinA neurological disease

genetics↗