Expression of the gene encoding the extracellular matrix glycoprotein SPARC in the developing and adult mouse brain.
The pattern of expression of the SPARC gene was examined during postnatal development of the mouse brain using in situ hybridization. At postnatal day 3 (P3), a strong signal representing SPARC mRNA was apparent in boundary layers such as the pia mater and the lining of the ventricles. By P12, increased levels of SPARC mRNA were noted in the cerebellum, midbrain and brain stem with a lower signal in more frontal areas, a pattern which was retained in the adult. This pronounced caudal versus frontal difference in SPARC mRNA levels was confirmed by Northern blot analysis. At P3, SPARC mRNA was detected in developing blood vessels in the cerebral cortex, suggesting a role for SPARC in angiogenesis. During development of the cerebellum, expression of SPARC mRNA became highly restricted to the Purkinje cellular layer and in the adult was localized to Bergmann glial cells rather than Purkinje neurons.