Selective ablation of an astroglial subset by toxic gene expression driven by tenascin promoter

Objective: In vitro culture, one of the astroglia-derived extracellular matrix proteins, tenascin, expressed highly in fibrous astrocytes, whereas it expressed only low levels in protoplasmic astrocytes. We devised a method of selectively altering the population of astroglial subsets in primary culture of astrocytes derived from embryonic mouse brains using toxic gene expression driven by the tenascin promoter. Methods: We have identified that the segment of 512-bases of 5′-flanking plus 243-bases leader sequences of the mouse tenascin gene contains maximum promoter activity in primary culture of astrocytes by deletion analysis of 5′-upstream region. This promoter element was used to specifically express the herpes simplex virus thymidine kinase (HSV-TK) gene in tenascin-positive astrocytes. Results: This strategy allowed us to selectively decrease tenascin-positive astrocytes at the optimal concentration of ganciclovir, which is cytotoxic in HSV-TK-expressing cells. Discussion: This approach should be useful for examining the role of the tenascin-negative astroglial subset in the development and regeneration of the central nervous system.