Gene expression analysis of murine cells producing amphotropic mouse leukaemia virus at a cultivation temperature of 32 and 37 °C

Cultivation of retrovirus packaging cells at 32 degreesC represents a common procedure to achieve high tifres in mouse retrovirus production. Gene expression profiling of mouse NIH 3T3 cells producing amphotropic mouse leukaemia virus 4070A revealed that 10% of the 1176 cellular genes investigated were regulated by temperature shift (37/32 degreesC), while 5% were affected by retrovirus infection. Strikingly, retrovirus production at 32 degreesC activated the cholesterol biosynthesis/transport pathway and caused an increase in plasma membrane cholesterol levels. Furthermore, these conditions resulted in transcriptional activation of smoothened (smo), patched (ptc) and gli-1; Smo, Ptc and Gli-1, as well as cholesterol, are components of the Sonic hedgehog (Shh) signalling pathway, which directs pattern formation, diversification and tumourigenesis in mammalian cells. These findings suggest a link between cultivation at 32 degreesC, production of MLV-A and the Shin signalling pathway.