Altered lipid content in CHO cells overexpressing the P5-ATPase ATP13A2

MOLINARI, MA. FLORENCIA; ADAMO HUGO P.; CORRADI, GERARDO R.; MAZZITELLI, LUCIANA R.; DE TEZANOS PINTO, FELICITAS

San Miguel de Tucuman

Congreso; Reunión Conjunta que incluye el III Congreso de LAFeBS, el IX Congreso Iberoamericano de Biofísica y la XLV Reunión Anual de la Sociedad Argentina de Biofísica; 2016

Sociedad Argentina de Biofísica

The P-type ion pumps are membrane transporters energized by ATP-hydrolysis. They were classified into five subfamilies termed P1-P5; the substrate specificity of P5 subfamily is still unknown. Five genes named ATP13A1-ATP13A5 that belong to the P5-ATPases are present in humans. Mutations in the ATP13A2 gene (also known as PARK9 or CNL12) underlay a form of Parkinson (1) and a form of Neuronal Ceroid Lipofuscinosis (2). ATP13A2 is localized in lysosomes and late endosomes (LE). Dysfunction of this protein diminishes the lysosomal degradation, the autophagic flux (3) and the exosome externalization (4). We have recently shown that ATP13A2 expression caused a reduction of the iron-induced lysosome membrane permeabilization (5), which suggests that ATP13A2 overexpression improves the lysosome and LE membrane integrity. In this line, we analyzed the accumulation of fluorescent analogs like phosphatidylethanolamine (NBD-PE) and ceramide (NBD-ceramide) in ATP13A2-expressing CHO cells by fluorescence microscopy. We found that the expression of ATP13A2 increases the NBD-PE fluorescence intensity, reflecting an augmented lipidosis in these cells. Besides, the ceramide-fluorescence intensity was reduced, suggesting that the degradation of membrane components that take place in acidic compartments is being affected. The PE content measured by fluorescence quenching assay in the mitochondrial fraction containing lysosomes and LEs of ATP13A2-expressing CHO cells, was increased in the cytoplasmic leaflet of these acidic vesicles. These results suggest that ATP13A2 may be involved in the lipid homeostasis of these subcellular organelles.