PT  - JOURNAL ARTICLE
AU  - Walter K. Nahm
AU  - Jeffrey L. Noebels
TI  - Nonobligate Role of Early or Sustained Expression of Immediate-Early Gene Proteins c-Fos, c-Jun, and Zif/268 in Hippocampal Mossy Fiber Sprouting
AID  - 10.1523/JNEUROSCI.18-22-09245.1998
DP  - 1998 Nov 15
TA  - The Journal of Neuroscience
PG  - 9245--9255
VI  - 18
IP  - 22
4099  - http://www.jneurosci.org/content/18/22/9245.short
4100  - http://www.jneurosci.org/content/18/22/9245.full
SO  - J. Neurosci.1998 Nov 15; 18
AB  - Axon sprouting in dentate granule cells is an important model of structural plasticity in the hippocampus. Although the process can be triggered by deafferentation, intense activation of glutamate receptors, and other convulsant stimuli, the specific molecular steps required to initiate and sustain mossy fiber (MF) reorganization are unknown. The cellular immediate early genes (IEGs)c-fos, c-jun, and zif/268are major candidates for the initial steps of this plasticity, because they encode transcription factors that may trigger cascades of activity-dependent neuronal gene expression and are strongly induced in all experimental models of MF sprouting. The mutant mouse stargazer offers an important opportunity to test the specific role of IEGs, because it displays generalized nonconvulsive epilepsy and intense MF sprouting in the absence of regional cell injury. Here we report that stargazer mice show no detectable elevations in c-Fos, c-Jun, or Zif/268 immediate early gene proteins (IEGPs) before or during MF growth. Experimental results in stargazer, including (1) a strong IEGP response to kainate-induced convulsive seizures, (2) no IEGP response after prolongation of spike-wave synchronization, (3) no IEGP increase at the developmental onset of seizures or after prolonged seizure suppression, and (4) unaltered levels of the intracellular Ca2+-buffering proteins calbindin-D28kor parvalbumin, exclude the possibility that absence of an IEGP response in stargazer is either gene-linked or suppressed by known refractory mechanisms. These data demonstrate that increased levels of these IEGPs are not an obligatory step in MF-reactive sprouting and differentiate the early downstream molecular cascades of two major seizure types.