DECREASED CYCLIN-DEPENDENT KINASE IN BRAIN OF PATIENTS WITH DOWN-SYNDROME

In order to study whether phosphokinases might be involved in the neur opathology of Down Syndrome (DS) and Alzheimer disease (AD), cyclin de pendent kinase (CDK) activity and protein, phosphokinase C (PKC) and p hosphokinase A (PKA) activities have been determined in frontal lobes of DS, AD and control brains. An enzyme linked immunosorbent assay (EL ISA) technique for CDK protein, and commercially available enzyme assa ys for CDK, PKC and PKA activities have been used. The major finding o f our study was the remarkable and significant decrease of CDK protein and activity in DS brains in comparison to AD and controls. PKC and P KA were unaffected in both, AD and DS. As CDK controls cell division a nd differentiation, lowered CDK levels could reflect impaired prolifer ation and differentiation in DS.