Differential expression of 14-3-3 protein isoforms in developing rat hippocampus, cortex, rostral migratory stream, olfactory bulb, and white matter

We investigated the differential immunoexpression of 14-3-3 proteins according to their 7 isoforms during the postnatal development of rat brains, primarily in the hippocampus, cortex, rostral migratory stream (RMS), olfactory bulb, and white matter. Wistar rats at different developmental stages, on postnatal days 2 (P2), P7, P14, P21 and P100 were obtained, and were incubated with each type of anti-14-3-3 isoform antibody. 14-3-3 common (COM)-like immunoreactivity (IR) which represents an epitope shared among the 7 isoforms was initially expressed in the olfactory bulb on P2. This IR was partially expressed in the dentate granule cells and hippocampal pyramidal neurons from P7, and increased during development. These chronological changes were similar to those obtained with beta, gamma, and eta isoforms. Epsilon isoform-like IR was initially identified in the cell body of cortical neurons and glia-like cells on P2. After P7, the IR was more intense in the neuropil of the cortex. This epsilon isoform-like IR was markedly accentuated in the stratum lucidum of the hippocampus after P7, where hippocampal mossy fibers terminate, functioning as a giant synapse. This suggests that epsilon isoforms may be associated with synaptogenesis of the hippocampal mossy fibers. Sigma isoform-like IR was observed in the nuclei of external plexiform layer cells of the olfactory bulb from P2 to P21, in the nuclei of the hippocampal pyramidal and dentate granule cells after P7 and in the nuclei of RMS cells after P7. Zeta and tau isoform-like IRs were mainly identified in the white matter and in oligodendroglial cells from P7 to P21. Different immunolocalizations of the 7 isoforms suggest that 14-3-3 protein isoforms are individually associated with neuronal development and synaptogenesis during postnatal formation of the rat brain.

► We investigated IR of 14-3-3 protein 7 isoforms during postnatal development of rat brains.
► 14-3-3COM IR was expressed in hippocampal neurons from P7, and increased during development.
► Epsilon isoform IR was markedly accentuated in the stratum lucidum of the hippocampus after P7.
► Sigma isoform IR was observed in nuclei of the hippocampal neurons and RMS cells after P7.
► Tau isoform IR was identified in the white matter and in oligodendroglial cells from P7 to P21.