Figure 4. Transient transfection assays of wild-type and mutant prSMN-pGL3 constructs.

Mutations in the +11Sp1, +37AhR, +56Sp1, +79Ets, +86IL-6 and +105Ets were created singly or in combination as shown schematically to the left of the bar graphs. The × indicates the presence of a given mutation within the constructs shown along the Y-axis. SMN promoter activity is expressed as RLU×10⁶ normalized against β-galactosidase activity as a measure of transfection efficiency (X-axis). Each construct was transiently transfected into undifferentiated (A) and differentiated (B) P19 cells. Note the different scale in (A, B) underscoring the lower SMN promoter activity in differentiated P19 cells. (C) The wild-type (m46p125) and mutant (+70Sp1, +97IL-6 and +115Ets cis-elements) mouse Smn promoter constructs schematically shown to the left of the bar graphs were transiently transfected into undifferentiated P19 cells. Asterisks identify those constructs that displayed SMN (A, B) or Smn promoter (C) activity significantly different from the corresponding wild-type minimal proximal SMN/Smn promoter constructs (m15p117 for A and B; or m46p125 for C) as determined using the Mann–Whitney U test. Asterisks identify statistically significant differences between mutant constructs (P≤0.05).