Presenilins (PS) are the catalytic components of γ-secretase complexes that mediate intramembrane proteolysis. Mutations in the PS genes are a major cause of familial early-onset Alzheimer disease and affect the cleavage of the amyloid precursor protein, thereby altering the production of the amyloid β-peptide. However, multiple additional protein substrates have been identified, suggesting pleiotropic functions of γ-secretase. Here, we demonstrate that inhibition of γ-secretase causes dysregulation of cellular lipid homeostasis, including up-regulation of liver X receptors, and complex changes in the cellular lipid composition. Genetic and pharmacological inhibition of γsecretase leads to strong accumulation of cytoplasmic lipid droplets, associated with increased levels of acylglycerols, but lowered cholesteryl esters. Furthermore, accumulation of lipid droplets was augmented by increasing levels of amyloid precursor protein C-terminal fragments, indicating a critical involvement of this γ-secretase substrate. Together, these data provide a mechanism that functionally connects γ-secretase activity to cellular lipid metabolism. These effects were also observed in human astrocytic cells, indicating an important function of γ-secretase in cells critical for lipid homeostasis in the brain.
Se describen seis especies nuevas del género de cucarachas Eurycotis Stål para la República Dominicana (Hispaniola). Se brindan diagnosis diferenciales, ilustraciones y comentarios para los táxones nuevos y las dos especies previamente conocidas de la Hispaniola.
Se describen siete especies nuevas del género de cucarachas Eurycotis Stål para la República Dominicana (Hispaniola). Se brindan diagnosis diferenciales, ilustraciones y comentarios para los táxones nuevos, y fotografías de los ejemplares tipos macho y hembra de E. tibialis Hebard, 1916.
Few scientists have dedicated themselves to the study of Colombia’s cockroach diversity. As a result, there are large gaps in the taxonomic knowledge of Colombian cockroach fauna that make species identification difficult and little information is available on their geographic distribution. Therefore, a taxonomic study of the suborder Blattaria was undertaken by examining the literature and studying specimens available in the country’s main entomological collections. A list of genera with their respective distribution in the various biogeographic regions was obtained. Two thousand, one hundred and forty six adult specimens, distributed in 4 families, 15 subfamilies, and 47 genera were examined and identified. The material examined comes from localities belonging to 31 of the Colombian territory’s 32 departments. Distribution data were obtained for 50 genera in seven biogeographic provinces, mainly in the North Andean and Chocó-Magdalena provinces. Seven genera are presented as new records for Colombia: Buboblatta, Cahita, Cariblatta, Euthlastoblatta, Litopeltis, Macrophyllodromia and Nahublattella. The total number of cockroach genera in Colombia is raised to 61.
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