SV-40 promoter

[Matthias Zeiner]

 In article <6321.lyc at ibms.sinica.edu.tw_POPMail.PC_3.2.2>,
 lyc at IBMS.SINICA.EDU.TW ("L.Y.Chau") wrote:
 
 > Hi,
 > I am doing transfection exp. on undifferentiated and DMSO-induced 
 > differentiated HL-60 cells.  The B-gal activity driven by SV-40 promoter is 
 > always 3-fold lower in differentiated HL-60.  Here comes the question!  Is 
 > SV-40 promoter down-regulated in differentiated cells?  If I need to 
 > normalize my transfection data, is there any other promoter I can use which 
 > is not regulated during differentiation?
 > 
 > Jonghwei

I've seen a similar phenomenon with HL60 cells some time ago. In cells 
that remained in the same culture medium for more than 2-3 days expression 
levels of several genes were reduced (in undifferentiated as well as in 
DMSO-differentiated cells). This is because the medium is depleted of 
essential growth factors, esp. insulin and transferrin and maybe 
accumulation of toxic products. The decrease of gene expression could be 
completely avoided by supplying the cells with fresh culture medium every 
2 days.
Hope this helps.

Matthias