AKAP350 knock down induces a decrease in NPM expression in leukemia cells.

MATTALONI, SM, GARCÍA, F, GOLDENRING, JR, LAROCCA, MC.

Carloz Paz, Argentina

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2008

AKAP350 is a Golgi and centrosomal scaffolding protein associated with the modulation of microtubule cytoskeleton. Among the proteins scaffolded by AKAP350 to the centrosomes, Ran GTPase and CDK2 modulate the recruitment and release of nucleophosmin (NPM), a key protein in centrosomal duplication. Interestingly, 60 % of normal karyotype acute myeloid leukemia (AML) present an isoform of NPM with changes in its centrosomal targeting domain (NPMc+), most of them as the unique mutation identified. Our aim was to study if AKAP350 modulates NPM expression, and to analyze if this has a differential impact on AML cells expressing NPMwt (THP1) and NPMc+ (OCI).We isolated centrosomes, and found that NPM centrosomal location did not differ between THP1 and OCI cells. We generated cells with decreased AKAP350 expression (A350-) by RNA interference. A350- cells exhibits a decrease in NPM levels in both cell lines (OCI -26%*; THP1 -34%*). In OCI, but not in THP1 cells, this decrease was associated with lost of cell viability (-9%*) and increase in the number of polynucleated cell-events (control: 0,95±0,58%; A350-: 3± 0,33%*). Our results indicate that AKAP350 down-expression induces a decrease in NPM levels that is specifically associated with a disorder in cell division in NPMc+ cells. These observations suggest alterations in centrosomal biology in NPMc+ AKAP350- cells. *p<0,05