Figure 2. GKN1 negatively regulates expression of telomere-related proteins.

(A) AGS and MKN1 cells transiently transfected with GKN1 showed increased TRF1 and decreased hTERT expression levels. (B) GKN1 stable transfectants, AGS^GKN1 and MKN1^GKN1, induced TRF1 expression and down-regulated hTERT and c-myc protein expression in whole cell lysates (WCL). (C) In the cytoplasmic fraction of stable transfectants, GKN1 down-regulated c-myc expression. (D) GKN1 completely reduced TRF1 and c-myc protein expression detected in the nucleus of mock stable cells. (E) Increased expression of TRF1 and decreased expression of the c-myc and hTERT proteins were observed in the chromatin fraction of GKN1 stable transfectants. The accuracy of fractionation was confirmed with a cytoplasmic marker (α-tubulin) and a chromatin marker (histone H4).