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Wiley, Hippocampus, 5(26), p. 658-667, 2015

DOI: 10.1002/hipo.22549

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Sprouty2 and -4 hypomorphism promotes neuronal survival and astrocytosis in a mouse model of kainic acid induced neuronal damage

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

Sprouty (Spry) proteins play a key role as negative feedback inhibitors of the Ras/Raf/MAPK/ERK pathway downstream of various receptor tyrosine kinases. Among the four Sprouty isoforms, Spry2 and Spry4 are expressed in the hippocampus. In this study, we analyzed possible effects of Spry2 and Spry4 hypomorphism on neurodegeneration and seizure thresholds in a mouse model of epileptogenesis. The Spry2/4 hypomorphs exhibited stronger ERK activation which was limited to the CA3 pyramidal cell layer and to the hilar region. The seizure threshold of Spry2/4(+/-) mice was significantly reduced at naive state but no difference to wildtype mice was observed one month following KA treatment. Histomorphological analysis revealed that dentate granule cell dispersion was diminished in Spry2/4(+/-) mice in the subchronic phase after KA injection. Neuronal degeneration was reduced in CA1 and CA3 principal neuron layers as well as in scattered neurons of the contralateral CA1 and hilar regions. Moreover, Spry2/4 reduction resulted in enhanced survival of somatostatin and neuropeptide Y expressing interneurons. GFAP staining intensity and number of reactive astrocytes markedly increased in lesioned areas of Spry2/4(+/-) mice as compared to wildtype mice. Taken together, although the seizure threshold is reduced in naive Spry2/4(+/-) mice, neurodegeneration and granule cell dispersion is mitigated following KA induced hippocampal lesions, identifying Spry proteins as possible pharmacological targets in brain injuries resulting in neurodegeneration. The present data are consistent with the established functions of the ERK pathway in astrocyte proliferation as well as protection from neuronal cell death and suggest a novel role of Spry proteins in the migration of differentiated neurons. This article is protected by copyright. All rights reserved.