bims-unfpre 2022-02-20 papers

Issue of 2022–02–20
four papers selected by
Susan Logue, University of Manitoba

Aging Cell. 2022 Feb 16. e13558

Aging alters the metabolic flux signature of the ER-unfolded protein response in vivo in mice.

Catherine P Ward, Lucy Peng, Samuel Yuen, John Halstead, Hector Palacios, Edna Nyangau, Hussein Mohammed, Naveed Ziari, Mohamad Dandan, Ashley E Frakes, Holly K Gildea, Andrew Dillin, Marc K Hellerstein.

Age is a risk factor for numerous diseases, including neurodegenerative diseases, cancers, and diabetes. Loss of protein homeostasis is a central hallmark of aging. Activation of the endoplasmic reticulum unfolded protein response (UPRER ) includes changes in protein translation and membrane lipid synthesis. Using stable isotope labeling, a flux "signature" of the UPRER in vivo in mouse liver was developed by inducing ER stress with tunicamycin and measuring rates of both proteome-wide translation and de novo lipogenesis. Several changes in protein synthesis across ontologies were noted with age, including a more dramatic suppression of translation under ER stress in aged mice as compared with young mice. Binding immunoglobulin protein (BiP) synthesis rates and mRNA levels were increased more in aged than young mice. De novo lipogenesis rates decreased under ER stress conditions in aged mice, including both triglyceride and phospholipid fractions. In young mice, a significant reduction was seen only in the triglyceride fraction. These data indicate that aged mice have an exaggerated metabolic flux response to ER stress, which may indicate that aging renders the UPRER less effective in resolving proteotoxic stress.

Keywords: aging; de novo lipogenesis; endoplasmic reticulum; proteome dynamics; proteomics; unfolded protein response

DOI: https://doi.org/10.1111/acel.13558

Cells. 2022 Feb 05. pii: 555. [Epub ahead of print]11(3):

C53 Interacting with UFM1-Protein Ligase 1 Regulates Microtubule Nucleation in Response to ER Stress.

Anastasiya Klebanovych, Stanislav Vinopal, Eduarda Dráberová, Vladimíra Sládková, Tetyana Sulimenko, Vadym Sulimenko, Věra Vosecká, Libor Macůrek, Agustin Legido, Pavel Dráber.

ER distribution depends on microtubules, and ER homeostasis disturbance activates the unfolded protein response resulting in ER remodeling. CDK5RAP3 (C53) implicated in various signaling pathways interacts with UFM1-protein ligase 1 (UFL1), which mediates the ufmylation of proteins in response to ER stress. Here we find that UFL1 and C53 associate with γ-tubulin ring complex proteins. Knockout of UFL1 or C53 in human osteosarcoma cells induces ER stress and boosts centrosomal microtubule nucleation accompanied by γ-tubulin accumulation, microtubule formation, and ER expansion. C53, which is stabilized by UFL1, associates with the centrosome and rescues microtubule nucleation in cells lacking UFL1. Pharmacological induction of ER stress by tunicamycin also leads to increased microtubule nucleation and ER expansion. Furthermore, tunicamycin suppresses the association of C53 with the centrosome. These findings point to a novel mechanism for the relief of ER stress by stimulation of centrosomal microtubule nucleation.

Keywords: CDK5RAP3; ER stress; UFL1; microtubule nucleation; γ-tubulin

DOI: https://doi.org/10.3390/cells11030555

JCI Insight. 2022 Feb 15. pii: e157203. [Epub ahead of print]

Targeting IRE1 endoribonuclease activity alleviates cardiovascular lesions in a murine model of Kawasaki disease vasculitis.

Stefanie Marek-Iannucci, Asli D Yildirim, Syed M Hamid, Asli B Ozdemir, Angela C Gomez, Begüm Kocatürk, Rebecca A Porritt, Michael C Fishbein, Takao Iwawaki, Magali Noval Rivas, Ebru Erbay, Moshe Arditi.

Kawasaki disease (KD) is the leading cause of non-congenital heart disease in children. Studies in mice and humans propound the NLRP3-IL-1β pathway as the principal driver of KD pathophysiology. Endoplasmic reticulum (ER) stress can activate the NLRP3 inflammasome, but the potential implication of ER stress in KD pathophysiology has not been investigated. We used human patient data and the Lactobacillus casei cell wall extract (LCWE) murine model of KD vasculitis to characterize the impact of ER stress on the development of cardiovascular lesions. KD patient transcriptomics and single-cell RNA sequencing of the abdominal aorta from LCWE-injected mice revealed changes in the expression of ER stress genes. Alleviating ER stress genetically, by conditional deletion of Inositol Requiring Enzyme-1 (IRE1) in myeloid cells, or pharmacologically, by inhibition of IRE1 endoribonuclease (RNase) activity, led to significant reduction of LCWE-induced cardiovascular lesion formation as well as reduced caspase-1 activity and IL-1β secretion. These results demonstrate the causal relationship of ER stress to KD pathogenesis, and highlight IRE1 RNase activity as a potential new therapeutic target.

Keywords: Cell stress; Immunology; Mouse models; Vascular Biology; Vasculitis

DOI: https://doi.org/10.1172/jci.insight.157203

Cells. 2022 Jan 27. pii: 433. [Epub ahead of print]11(3):

Mitochondria Fusion upon SERCA Inhibition Prevents Activation of the NLRP3 Inflammasome in Human Monocytes.

Ana Catarina Pereira, Nuno Madeira, Sofia Morais, António Macedo, Maria Teresa Cruz, Cláudia M F Pereira.

Sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) is a crucial component of the cellular machinery responsible for Ca2+ homeostasis. The selective inhibition of SERCA by thapsigargin (TG) leads to perturbations in Ca2+ signaling, which can trigger endoplasmic reticulum (ER) stress. The unfolded protein response (UPR) pathway is activated in response to ER stress and induces an adaptive response to preserve cell survival or committee cells to programmed death, depending on stress duration and/or level. Early stages of ER stress stimulate mitochondrial metabolism to preserve survival but under chronic ER stress conditions, mitochondrial dysfunction is induced, which, in turn, can enhance inflammation through NLRP3 inflammasome activation. This study was aimed at investigating the role of SERCA inhibition on NLRP3 inflammasome activation in human monocytes, which was evaluated in primary monocytes isolated from healthy individuals and in the THP-1 human monocytic cell line. Findings obtained in both THP-1 and primary monocytes demonstrate that SERCA inhibition triggered by TG does not activate the NLRP3 inflammasome in these innate immune cells since IL-1β secretion was not affected. Results from THP-1 monocytes showing that SERCA inhibition increases mitochondrial Ca2+ content and fusion, in the absence of changes in ROS levels and membrane potential, support the view that human monocytes counteract ER stress that arises from inhibition of SERCA through modulation of mitochondrial morphology towards mitochondria fusion, thus preventing NLRP3 inflammasome activation. Overall, this work contributes to a better understanding of the molecular mechanisms that modulate the activity of the NLRP3 inflammasome leading to sterile inflammation, which are still poorly understood.

Keywords: calcium homeostasis; endoplasmic reticulum (ER) stress; immune system; mitochondria dynamics; sterile inflammation

DOI: https://doi.org/10.3390/cells11030433