Upregulation of the HLH Id gene family in neural progenitors and glial cells of the rat spinal cord following contusion injury

作者：Tzeng SF; Bresnahan JC; Beattie MS; de Vellis J^*

来源：Journal of Neuroscience Research, 2001, 66(6): 1161-1172.

• inhibitors of DNA binding
• ID
• HLH transcription factor
• spinal cord injury
• neural progenitor
• nestin
• astrocytes

Spinal cord injury (SCI) leads to a complex sequence of cellular responses, including astrocyte activation, oligodendrocyte death, and ependymal cell proliferation. Inhibitors of DNA binding (Id1, Id2, ld3) belong to a helix-loop-helix (HLH) gene family. ld genes have been implicated in playing a vital role in the proliferation of many cell types, including astrocytes and myoblasts. In the present study, the expression of Id family members in spinal cord after contusion injury was investigated by in situ hybridization. Id1, Id2, and ld3 mRNA expression was upregulated 5 mm rostral and caudal to the lesion center, and reached maximal levels 3 days after SCI. In addition, cell populations expressing Id1, Id2, and ld3 mRNA were maximally increased 3 days after SCI. The increase in Id2 and ld3 mRNA expression and Id2 and ld3 mRNA+ cells was still observed at 8 days. The Id mRNA expressing cells were phenotyped by combining immunostaining of cell-specific markers with in situ hybridization. Glial fibrillary acidic protein (GFAP)+ astrocytes were found to express all three ld mRNA, whereas S-100 alpha+ astrocytes only expressed high levels of Id2 and ld3 mRNA. Cells having a neural progenitor morphology and the marker nestin appeared after SCI and they expressed Id1, Id2, and Id3 mRNA. Interestingly, some Rip+ oligodendrocytes located in the areas close to the central canal expressed Id3 mRNA after injury. In conclusion, Id genes are upregulated in a time-dependent manner in astrocytes, oligodendrocytes, and neural progenitor subpopulations after SCl, suggesting that they play major roles in cellular responses following SCI.

• 出版日期2001-12-15