EXPRESSION OF DA11, A NEURONAL-INJURY-INDUCED FATTY-ACID-BINDING PROTEIN, COINCIDES WITH AXON GROWTH AND NEURONAL DIFFERENTIATION DURING CENTRAL-NERVOUS-SYSTEM DEVELOPMENT

DA11 is the first fatty acid binding protein (FABP) for which gene exp ression has been shown to be upregulated following neuronal injury in the adult peripheral nervous system. To understand better the potentia l regulatory role(s) of this unique FABP in axonal growth and neuronal differentiation, we undertook a temporal and spatial study of DA11 ge ne expression in the developing rat central nervous system (CNS:). Tra nsient upregulation of DA11 mRNA and protein levels in CNS tissues wer e quantified by Northern blot hybridization and Western immunoblot ana lyses at different developmental ages. Homogenates of embryonic and ne onatal cerebral cortex, cerebellum, brainstem, and hippocampal tissues contained 100-fold more DA11 mRNA and protein than corresponding adul t tissues. Significant increase in DA11 mRNA was observed as early as embryonic day (E) 14 in cerebral cortex and cerebellum and E19 in brai n stem and hippocampus. Postnatal levels of DA11 remained elevated thr ough postnatal day (P) 10 in cerebral cortex, P14 in brain stem and hi ppocampus, and P20 in cerebellum. Localization of DA11-like immunoreac tivity to specific CNS tissues, cell types, and intracellular compartm ents at P9 revealed a spatial pattern of neuronal expression different than that reported for other FABPs. DA11 protein was detected in the nucleus, cytoplasm, axons, and dendrites of differentiating neurons in cerebral cortex, hippocampus, cerebellum, brain stem, spinal cord, an d olfactory bulb. The strong association of DA11 gene expression with development throughout the CNS suggests that this unique FABP plays an important role in axonal growth and neuronal differentiation in many different neuronal populations. (C) 1997 Wiley-Liss, Inc.