Transcriptional up-regulation of the protooncogenes c-fos and c-jun following vitreous removal and short-term in vitro culture of bovine lenses

Chemical (mainly oxidative) and mechanical (anterior capsule injury) stress es have been reported to upregulate the expression of the protooncogenes c- fos and c-jun in the lens. Another potentially stressful, yet largely unexp lored condition, inherent to all experiments requiring the in vitro culturi ng of isolated lenses, is vitreous removal, Based on the results of an exte nsive RNA gel blot analysis conducted on epithelial/capsule preparations is olated from calf lenses dissected and cultured under different conditions, we show here, that lens isolation and short-term culture (1-2.5 hr, without any significant GSH depletion) result in a strong and time-dependent up-re gulation of the c-jun and c-fos mRNAs. This response, which relies on trans criptional protooncogene activation and is more intense for c-fos than for c-jun, is in part prevented by the preservation of the lens-vitreous contac t, but not by the culture of vitreous-stripped lenses on a vitreous bed. Su pplementation of the culture medium with the antioxidant N-acelyl-cysleine slightly reduced the c-jun, but not the c-fos response. Protooncogene up-re gulation thus appears to be mainly determined by the disruption of critical lens-vitreous interactions. Since this response takes place in the epithel ial cells, these data also point to the existence of a communication mechan ism whereby a posteriorly applied mechanical stress is transmitted to, and perceived by, the anterior lens surface. (C) 2001 Academic Press.