Fig. 4

Sp1 upregulates the LRRK2 gene expression. a-d Sp1 overexpression increased LRRK2 mRNA expression level. Sp1 expression plasmid was transfected into HEK293 cells (a) or MN9D cells (c). Cell lysates were harvested 48 h after transfection and total RNA was isolated for RT-PCR. The products of amplified LRRK2 and β-actin genes were analyzed on a 1.5 % agarose gel. Quantification was performed by ImageJ software and endogenous LRRK2 mRNA level was normalized against β-actin. e HEK292 cells were transfected with scrambled siRNA or Sp1 siRNA, and endogenous LRRK2 mRNA level was measured by RT-PCR after 48 h and analyzed on a 1.5 % agarose gel. g HEK293 cells were transfected as mentioned before and cell lysates were harvested 48 h after transfection. Endogenous LRRK2 protein and overexpressed Sp1 were examined by immunoblotting. i HEK293 cells were transfected with negative control siRNA or Sp1 siRNA. After 48 h, cell lysate was harvested for determining LRRK2 and Sp1 protein level by immunoblotting. Quantification of the band intensity in (f), (h), and (j) was performed by ImageJ software. The values in this figure represent means ± SEM. n =3, *p < 0.05, analyzed by Student’s t-test