SENSE AND ANTISENSE TRANSCRIPTS OF THE DEVELOPMENTALLY-REGULATED MURINE HSP70.2 GENE ARE EXPRESSED IN DISTINCT AND ONLY PARTIALLY OVERLAPPING AREAS IN THE ADULT BRAIN

We have examined the spatial pattern of expression of a member of the hsp70 gene family, hsp70.2, in the mouse central nervous system. Surpr isingly, RNA blot analysis and in situ hybridization revealed abundant expression of an 'antisense' hsp70.2 transcript in several areas of a dult mouse brain. Two different transcripts recognized by sense and an tisense riboprobes for the hsp70.2 gene were expressed in distinct and only partially overlapping neuronal populations. RNA blot analysis re vealed low levels of the 2.7 kb transcript of hsp70.2 in several areas of the brain, with highest signal in the hippocampus. Abundant expres sion of a slightly larger (similar to 2.8 kb) 'antisense' transcript w as detected in several brain regions, notably in the brainstem, cerebe llum, mesencephalic tectum, thalamus, cortex, and hippocampus. In situ hybridization revealed that the sense and antisense transcripts were both predominantly neuronal and localized to the same cell types in th e granular layer of the cerebellum, trapezoid nucleus of the superior olivary complex, locus coeruleus and hippocampus. The hsp70.2 antisens e transcripts were particularly abundant in the frontal cortex, dentat e gyrus, subthalamic nucleus, zona incerta, superior and inferior coll iculi, central gray, brainstem, and cerebellar Purkinje cells. Our fin dings have revealed a distinct cellular and spatial localization of bo th sense and antisense transcripts, demonstrating a new level of compl exity in the function of the heat shock genes.