The role of CHMP2B mutations in astrocytic dysfunction: implications for neurodegeneration

Abstract

The ESCRT machinery is a group of cytosolic protein complexes whose main function is to form intraluminal vesicles. CHMP2B is a protein subunit of the ESCRT III complex which, when mutated, has been seen to cause a rare familial form of frontotemporal dementia. These mutations produce aberrant endocytic and autophagic activity within cells. Astrocytes have been implicated in virtually all neuropathologies and are responsible for a variety of key functions in the brain, one of which is glutamate regulation. CHMP2B has been reported to be ubiquitously expressed however no research has specifically investigated it in astrocytes despite their emerging role in these neuropathologies including frontotemporal dementia. This project aimed to determine CHMP2B expression in astrocytes and elucidate whether the FTD associated mutation CHMP2BIntron5 affected basic astrocyte biology. Western blotting and immunofluorescence staining of cell lines was conducted to confirm expression of CHMP2B in astrocytes and revealed that CHMP2B is expressed in astrocytes. Following confirmation of expression transient transfection of cells was used to create an expression model of CHMP2BIntron5 in order to analyse the effects of this mutation on cell morphology and localisation of the glutamate transporters EAAT1 and EAAT2. Morphological analysis showed no difference in cells when comparing CHMP2BWT and CHMP2BIntron5 nor was any difference in glutamate transporter localisation observed. This project did not find any alterations to basic astrocyte biology when exposed to mutations in CHMP2B.