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. 2010 Jan;24(1):296–308. doi: 10.1096/fj.09-135087

Figure 5.

Figure 5.

Down-regulation of CerS6 specifically activates the ATF6/CHOP arm of ER-stress response pathways. A) Left panels: specific knockdown of ATF4, ATF6, and IRE1 using siRNAs was confirmed using RT-PCR (top panel) and by Western blotting (bottom panel). Right panel: functional down-regulation of ATF4 in response to siRNA transfection was confirmed by analysis of REDD1 mRNA levels by Q-RT-PCR in the absence and presence of tunicamycin (Tm). B, C) Roles of ATF4, ATF6, and IRE1 in the regulation of caspase 3 activation (B) or CHOP mRNA (C) in response to down-regulation of CerS6 were examined. D) Roles of down-regulation of CerS6 in the regulation of ATF6 activation in UM-SCC-22A cells were examined, following transfections with N-terminal FLAG-tagged ATF6 and/or CerS6 siRNA. Cleaved and uncleaved ATF6 were detected by anti-FLAG immunoprecipitation followed by immunoblotting (left panel). Data represent 3 independent experiments. Band intensities were quantified and plotted as cleaved to full-length ATF6 ratio (right panel). Bars represent means ± sd from at least 2 experiments. *P < 0.05.