ATF6alpha optimizes long-term endoplasmic reticulum function to protect cells from chronic stress.

In vertebrates, three proteins--PERK, IRE1alpha, and ATF6alpha--sense protein-misfolding stress in the ER and initiate ER-to-nucleus signaling cascades to improve cellular function. The mechanism by which this unfolded protein response (UPR) protects ER function during stress is not clear. To address this issue, we have deleted Atf6alpha in the mouse. ATF6alpha is neither essential for basal expression of ER protein chaperones nor for embryonic or postnatal development. However, ATF6alpha is required in both cells and tissues to optimize protein folding, secretion, and degradation during ER stress and thus to facilitate recovery from acute stress and tolerance to chronic stress. Challenge of Atf6alpha null animals in vivo compromises organ function and survival despite functional overlap between UPR sensors. These results suggest that the vertebrate ATF6alpha pathway evolved to maintain ER function when cells are challenged with chronic stress and provide a rationale for the overlap among the three UPR pathways.

Treatment of advanced or recurrent cervical cancer with Cisplatin or Cisplatin containing regimens: a cost effective analysis.

BACKGROUND: Trials have demonstrated improvements in survival with adding paclitaxel (P) or topotecan (T) to cisplatin (C) for the treatment of advanced cervical cancer. We sought to evaluate the cost effectiveness of these regimens. METHODS: A decision model was developed based on Gynecologic Oncology Group (GOG) protocols 169 and 179. Arm 1 is 6 cycles of cisplatin. Arm 2 is 6 cycles of CP while arm 3 is 6 cycles of CT. Parameters include overall survival (OS), cost and complications. Sensitivity analyses were performed. RESULTS: The incremental cost-effectiveness ratio (ICER) for C versus CP is $13,654/quality-adjusted life-year (QALY) gained. For CT compared to C, the ICER is $152,327/QALY. When compared simultaneously, CT is dominated. At a willingness to pay (WTP) threshold of $50,000/QALY, C is the preferred option but CP is acceptable. Sensitivity analyses suggest that CT would become the preferred option if it was to improve OS to 24 months (compared to 9.4 months). CONCLUSIONS: In this model, CP is an acceptable alternative to cisplatin for the treatment of these patients with an increase in cost of only $13,654/QALY. The addition of topotecan did not increase survival enough to justify the increased cost.

UPR pathways combine to prevent hepatic steatosis caused by ER stress-mediated suppression of transcriptional master regulators.

The unfolded protein response (UPR) is linked to metabolic dysfunction, yet it is not known how endoplasmic reticulum (ER) disruption might influence metabolic pathways. Using a multilayered genetic approach, we find that mice with genetic ablations of either ER stress-sensing pathways (ATF6alpha, eIF2alpha, IRE1alpha) or of ER quality control (p58(IPK)) share a common dysregulated response to ER stress that includes the development of hepatic microvesicular steatosis. Rescue of ER protein processing capacity by the combined action of UPR pathways during stress prevents the suppression of a subset of metabolic transcription factors that regulate lipid homeostasis. This suppression occurs in part by unresolved ER stress perpetuating expression of the transcriptional repressor CHOP. As a consequence, metabolic gene expression networks are directly responsive to ER homeostasis. These results reveal an unanticipated direct link between ER homeostasis and the transcriptional regulation of metabolism, and suggest mechanisms by which ER stress might underlie fatty liver disease.