EXPRESSION OF MESSENGER-RNAS ENCODING ARPP-16 19, ARPP-21, AND DARPP-32 IN HUMAN BRAIN-TISSUE/

In this study we have isolated and sequenced human cDNAs for the phosp hoproteins DARPP-32, ARPP-21, and ARPP-16/19, and have compared these sequences to previously characterized bovine and rat cDNAs. In situ hy bridization and Northern blot analysis with the human cDNA probes were used to study the expression of mRNAs encoding ARPP-16/19, ARPP-21, a nd DARPP-32 in human postmortem brain tissue. In situ hybridization wa s performed using horizontal whole hemisphere sections. Five represent ative levels of the brain ranging from 71 mm to 104 mm ventral to vert ex were examined. All three probes showed distinct hybridization patte rns in the caudate nucleus, putamen, nucleus accumbens, and the amygda loid complex. For ARPP-16/19 mRNA, a hybridization signal comparable t o the signal in caudate nucleus, putamen, and nucleus accumbens was al so detected in the neocortex. ARPP-21 and DARPP-32 mRNA, on the other hand, were present in lower levels in neocortical regions. DARPP-32 mR NA was abundant in the cerebellar cortex at the level of the Purkinje cell layer. High levels of ARPP-16/19 and ARPP-21 mRNA were also found in the cerebellar cortex, where they were confined to deeper layers. The present result demonstrate that mRNAs for the three phosphoprotein s are expressed in overlapping, but also distinct, areas of the human brain that in many cases coincide with previously described distributi on of the dopamine D-1 receptor.