Fig. 6

Knockdown of CCAT1 promotes PTBP1 degradation through the ubiquitin / proteasome pathway. A, B Knockdown or ectopic expression of CCAT1 altered protein levels but not mRNA levels of PTBP1 in GC cells. C PTBP1 locations in GC cells with CCAT1 knockdown or overexpression were determined by IF and FISH (Scale bars = 50 µm). D Western blot analyses confirmed that silencing or ectopic expressing of CCAT1 led to an obvious decrease or increase in PTBP1 levels within the nuclear fraction (C: cytoplasm, N: nucleus). E The half-life of PTBP1 was decreased in CCAT1-knockdown GC cells treated with CHX. F Protein band intensity was analyzed by Image J. G Treatment of GC cells with MG132 restored the degradation of PTBP1 protein due to CCAT1 downregulation. H The ubiquitination level of PTBP1 was significantly elevated when knockdown of CCAT1 in GC cells, and that phenomenon was more obvious in the presence of MG132. The data are presented as the mean values ± SD from three independent experiments. Data were statistically evaluated using the Multiple unpaired t-tests (A) and 2-way ANOVA with Sídák's multiple comparisons test (F). ^ns p > 0.05, ^*p < 0.05, ^**p < 0.01