Neuronal expression of mint1 and mint2, novel multimodular proteins, in adult murine brain

Mints are multimodular adapter proteins in functioning membrane transport a nd organization. Mint1 and mint2 are neuron-specific. We localized these is oforms in mouse brain. By in situ hybridization, mRNA encoding mint1 or min t2 was expressed in neurons throughout the brain. Mint1 mRNA expression was greatest in the limbic system including cingulate cortex, hippocampus, ant erior thalamic nuclei, medial habenular nucleus, and mammillary body, Mint2 mRNA was rich in cerebral cortex, entorhinal cortex, and hippocampus, but less prominent in other limbic structures. Mint1 mRNA and mint2 mRNA were d istributed among hippocampal pyramidal neurons, while mint2 mRNA was especi ally abundant in CA3. Mint1, but not Mint2 mRNA was abundant in the substan tia nigra pars compacta. Immunohistochemistry visualized mint proteins in a xon terminals and neuronal somata, generally following mRNA distribution. I n the hippocampus, mint1 was rich in the entorhinal projections and mossy f ibers of the dentate gyrus, while mint2 was rich in commisural fibers from the contralateral hippocampus and in CAI. Mint1 intensely stained catechola mine-containing neurons such as the substantia nigra pars compacta, ventral tegmental area, and locus ceruleus. Mint2 protein was ubiquitous in these regions. Mint1 and mint2 distribution also differed elsewhere in the brains tem and in the cerebellum. Central nervous system neurons, then, predominan tly express either mint1 or mint2. Mints may be involved in synaptic vesicl e transport toward the active zone, also participating in transport of cert ain membrane proteins toward the postsynaptic density. Mint1 and mint2 may divide roles either regionally or depending on neuronal functional characte ristics. (C) 2001 Elsevier Science BY All rights reserved.