Cell death–associated lipid droplet protein CIDE-A is a noncanonical marker of endoplasmic reticulum stress
Yoshiaki Morishita, Aaron P. Kellogg, Dennis Larkin, Wei Chen, Suryakiran Vadrevu, Leslie Satin, Ming Liu, Peter Arvan
Yoshiaki Morishita, Aaron P. Kellogg, Dennis Larkin, Wei Chen, Suryakiran Vadrevu, Leslie Satin, Ming Liu, Peter Arvan
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Research Article Endocrinology

Cell death–associated lipid droplet protein CIDE-A is a noncanonical marker of endoplasmic reticulum stress

Abstract

Secretory protein misfolding has been linked to ER stress and cell death. We expressed a TGrdw transgene encoding TG-G(2298)R, a misfolded mutant thyroglobulin reported to be linked to thyroid cell death. When the TGrdw transgene was expressed at low level in thyrocytes of TGcog/cog mice that experienced severe ER stress, we observed increased thyrocyte cell death and increased expression of CIDE-A (cell death-inducing DFFA-like effector-A, a protein of lipid droplets) in whole thyroid gland. Here we demonstrate that acute ER stress in cultured PCCL3 thyrocytes increases Cidea mRNA levels, maintained at least in part by increased mRNA stability, while being negatively regulated by activating transcription factor 6 — with similar observations that ER stress increases Cidea mRNA levels in other cell types. CIDE-A protein is sensitive to proteasomal degradation yet is stabilized by ER stress, and elevated expression levels accompany increased cell death. Unlike acute ER stress, PCCL3 cells adapted and surviving chronic ER stress maintained a disproportionately lower relative mRNA level of Cidea compared with that of other, classical ER stress markers, as well as a blunted Cidea mRNA response to a new, unrelated acute ER stress challenge. We suggest that CIDE-A is a novel marker linked to a noncanonical ER stress response program, with implications for cell death and survival.

Authors

Yoshiaki Morishita, Aaron P. Kellogg, Dennis Larkin, Wei Chen, Suryakiran Vadrevu, Leslie Satin, Ming Liu, Peter Arvan

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Figure 5

In response to acute ER stress, Cidea mRNA elevation is maintained, at least, in part, by enhanced mRNA stability.

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In response to acute ER stress, Cidea mRNA elevation is maintained, at l...
Replicate wells of PCCL3 cells were either untreated or treated with tunicamycin (TUN 0.1 μg/mL) at time = –12 hours or –24 hours. One set of wells were cotreated with a low dose of the transcription blocker, actinomycin D (5 ng/mL), as indicated. At time 0, the cells were lysed, and mRNA levels were measured by qRT-PCR for BiP (A), Chop (B), or Cidea (C). The data show the mean ± SD (from 3 independent experiments in which each sample had 3 biological replicates); *P < 0.05 TUN + actinomycin D treatment versus TUN only. (D) Replicate wells of PCCL3 cells were either untreated or treated with tunicamycin (TUN 0.1 μg/mL) for 24 hours. During the last 12 hours, the cells were also either untreated or treated with a high dose of actinomycin D (5 μg/mL), as indicated. The ER stress–induced rise of BiP and Chop mRNA levels was almost completely blocked by actinomycin D treatment in the last 12 hours, whereas the increased Cidea mRNA level was completely unaffected; error bars represent mean ± SD from 3 independent experiments in which each sample had 3 independent biological replicates; *P < 0.05 versus TUN-treated cells without actinomycin D treatment (1-way ANOVA).