Publications by authors named "Scott A Oakes"

36 Publications

Cannabidiol Inhibits SARS-CoV-2 Replication and Promotes the Host Innate Immune Response.

bioRxiv 2021 Mar 10. Epub 2021 Mar 10.

The rapid spread of COVID-19 underscores the need for new treatments. Here we report that cannabidiol (CBD), a compound produced by the cannabis plant, inhibits SARS-CoV-2 infection. CBD and its metabolite, 7-OH-CBD, but not congeneric cannabinoids, potently block SARS-CoV-2 replication in lung epithelial cells. CBD acts after cellular infection, inhibiting viral gene expression and reversing many effects of SARS-CoV-2 on host gene transcription. CBD induces interferon expression and up-regulates its antiviral signaling pathway. A cohort of human patients previously taking CBD had significantly lower SARS-CoV-2 infection incidence of up to an order of magnitude relative to matched pairs or the general population. This study highlights CBD, and its active metabolite, 7-OH-CBD, as potential preventative agents and therapeutic treatments for SARS-CoV-2 at early stages of infection.
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http://dx.doi.org/10.1101/2021.03.10.432967DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7987002PMC
March 2021

Endoplasmic Reticulum Stress Signaling in Cancer Cells.

Authors:
Scott A Oakes

Am J Pathol 2020 05 27;190(5):934-946. Epub 2020 Feb 27.

Department of Pathology, Hellen Diller Family Comprehensive Cancer Center, University of California, San Francisco, California; Department of Pathology, Biological Sciences Division, Committee on Cancer Biology, Comprehensive Cancer Center, University of Chicago, Chicago, Illinois. Electronic address:

To survive, cancer cells must resist numerous internal and environmental insults associated with neoplasia that jeopardize proteostasis within the endoplasmic reticulum (ER). Solid and hematopoietic tumors often experience genomic instability, oncogene activation, increased protein secretion demands, and somatic mutations in proteins handled by the secretory pathway that impede their folding. Invasion or metastasis into foreign environments can expose tumor cells to hypoxia, oxidative stress, lack of growth signals, inadequate amino acid supplies, glucose deprivation, and lactic acidosis, all of which pose challenges for protein processing in the ER. Together, these conditions can promote the buildup of misfolded proteins in the ER to cause ER stress, which then activates the unfolded protein response (UPR). An intracellular signaling network largely initiated by three ER transmembrane proteins, the UPR constantly surveils protein folding conditions within the ER lumen and when necessary initiates counteractive measures to maintain ER homeostasis. Under mild or moderate levels of ER stress, the homeostatic UPR sets in motion transcriptional and translational changes that promote cell adaption and survival. However, if these processes are unsuccessful at resolving ER stress, a terminal UPR program dominates and actively signals cell suicide. This article summarizes the mounting evidence that cancer cells are predisposed to ER stress and vulnerable to targeted interventions against ongoing UPR signaling.
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http://dx.doi.org/10.1016/j.ajpath.2020.01.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7237829PMC
May 2020

Parallel Signaling through IRE1α and PERK Regulates Pancreatic Neuroendocrine Tumor Growth and Survival.

Cancer Res 2019 12 31;79(24):6190-6203. Epub 2019 Oct 31.

Department of Pathology, University of California, San Francisco, San Francisco, California.

Master regulators of the unfolded protein response (UPR), IRE1α and PERK, promote adaptation or apoptosis depending on the level of endoplasmic reticulum (ER) stress. Although the UPR is activated in many cancers, its effects on tumor growth remain unclear. Derived from endocrine cells, pancreatic neuroendocrine tumors (PanNET) universally hypersecrete one or more peptide hormones, likely sensitizing these cells to high ER protein-folding stress. To assess whether targeting the UPR is a viable therapeutic strategy, we analyzed human PanNET samples and found evidence of elevated ER stress and UPR activation. Genetic and pharmacologic modulation of IRE1α and PERK in cultured cells, xenograft, and spontaneous genetic (RIP-Tag2) mouse models of PanNETs revealed that UPR signaling was optimized for adaptation and that inhibiting either IRE1α or PERK led to hyperactivation and apoptotic signaling through the reciprocal arm, thereby halting tumor growth and survival. These results provide a strong rationale for therapeutically targeting the UPR in PanNETs and other cancers with elevated ER stress. SIGNIFICANCE: The UPR is upregulated in pancreatic neuroendocrine tumors and its inhibition significantly reduces tumor growth in preclinical models, providing strong rationale for targeting the UPR in these cancers.
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http://dx.doi.org/10.1158/0008-5472.CAN-19-1116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6911642PMC
December 2019

Elastase 3B mutation links to familial pancreatitis with diabetes and pancreatic adenocarcinoma.

J Clin Invest 2019 08 1;129(11):4676-4681. Epub 2019 Aug 1.

Department of Pathology.

While improvements in genetic analysis have greatly enhanced our understanding of the mechanisms behind pancreatitis, it continues to afflict many families for whom the hereditary factors remain unknown. Recent evaluation of a patient with a strong family history of pancreatitis sparked us to reexamine a large kindred originally reported over 50 years ago with an autosomal dominant inheritance pattern of chronic pancreatitis, diabetes and pancreatic adenocarcinoma. Whole exome sequencing analysis identified a rare missense mutation in the gene encoding pancreas-specific protease Elastase 3B (CELA3B) that cosegregates with disease. Studies of the mutant protein in vitro, in cell lines and in CRISPR-Cas9 engineered mice indicate that this mutation causes translational upregulation of CELA3B, which upon secretion and activation by trypsin leads to uncontrolled proteolysis and recurrent pancreatitis. Although lesions in several other pancreatitic proteases have been previously linked to hereditary pancreatitis, this is the first known instance of a mutation in CELA3B and a defect in translational control contributing to this disease.
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http://dx.doi.org/10.1172/JCI129961DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6819098PMC
August 2019

A Medical Student Inquiry Behavior Assessment Tool: Development and Validity Evidence.

Acad Med 2019 04;94(4):586-594

S. Brondfield was internal medicine chief resident at the time of the study and is currently chief hematology/oncology fellow, Department of Medicine, University of California, San Francisco, San Francisco, California. C. Boscardin is associate professor, Department of Medicine, University of California, San Francisco, San Francisco, California. G. Strewler is professor, Department of Medicine, University of California, San Francisco, San Francisco, California. K. Hyland is professor, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California. S.A. Oakes is professor, Department of Pathology, University of California, San Francisco, San Francisco, California. H. Nishimura was research analyst, Office of Research and Development in Medical Education, University of California, San Francisco, San Francisco, California, at the time of the study. J. Crawford was curriculum manager, Office of the Dean, University of California, San Francisco, San Francisco, California, at the time of the study. K.E. Hauer is professor, Department of Medicine, University of California, San Francisco, San Francisco, California.

Purpose: The University of California, San Francisco (UCSF) School of Medicine's Bridges curriculum is designed to teach inquiry: the process of approaching problems with curiosity, challenging current concepts, and creating new knowledge. The authors aimed to develop and gather validity evidence for a tool to guide development of medical student inquiry behaviors in small groups.

Method: The authors reviewed the literature to identify inquiry behaviors, verified findings with an expert focus group, and synthesized the results into 40 behaviors. In a modified two-round Delphi survey in 2016, faculty and students rated the behaviors for inclusion in the tool. Feedback from cognitive interviews and a pilot helped refine the tool. In 2016-2017, the authors implemented the final tool for 152 first-year UCSF medical students in inquiry small groups as a faculty assessment and a student self-assessment each quarter.

Results: The two-round response rate was 77% (36/47). Five behaviors were selected for inclusion in the tool: select relevant questions to pursue; justify explanations with evidence; critically evaluate his/her explanation in light of alternative possibilities; allow for the possibility that his/her own knowledge may not be completely correct; and collaborate well with peers. During implementation, faculty and student scores increased on most items, indicating skills development over time. Content, response process, internal structure, and consequential validity evidence is presented.

Conclusions: The tool's five items are observable, measurable core inquiry behaviors. The tool is ready for use by small-group facilitators within inquiry-based curricula to promote student self-assessment and guide feedback to students.
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http://dx.doi.org/10.1097/ACM.0000000000002520DOI Listing
April 2019

Bilateral Choroidal Metastases from Pancreatic Adenocarcinoma.

Ophthalmology 2017 12;124(12):1825

Departments of Ophthalmology & Visual Sciences and Pathology, University of Michigan, Ann Arbor, Michigan.

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http://dx.doi.org/10.1016/j.ophtha.2017.08.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5821071PMC
December 2017

CPEB4 links the clock and the UPR to protect the liver.

Nat Cell Biol 2017 01;19(2):79-81

Department of Pathology, Diabetes Center, and Helen Diller Family Comprehensive Cancer Center at the University of California, San Francisco, California 94143, USA.

Under misfolded protein stress, the endoplasmic reticulum (ER) activates the unfolded protein response (UPR) to restore homeostasis, or commits the cell to apoptosis. A study now uncovers how the UPR is governed by the circadian clock to adjust ER protein-folding capacity to metabolic demand and protect against liver damage.
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http://dx.doi.org/10.1038/ncb3460DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5555618PMC
January 2017

Endoplasmic reticulum proteostasis: a key checkpoint in cancer.

Authors:
Scott A Oakes

Am J Physiol Cell Physiol 2017 Feb 16;312(2):C93-C102. Epub 2016 Nov 16.

Department of Pathology, Diabetes Center, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California

The unfolded protein response (UPR) is an intracellular signaling network largely controlled by three endoplasmic reticulum (ER) transmembrane proteins, inositol-requiring enzyme 1α, PRK-like ER kinase, and activating transcription factor 6, that monitor the protein-folding status of the ER and initiate corrective measures to maintain ER homeostasis. Hypoxia, nutrient deprivation, proteasome dysfunction, sustained demands on the secretory pathway or somatic mutations in its client proteins, conditions often encountered by cancer cells, can lead to the accumulation of misfolded proteins in the ER and cause "ER stress." Under remediable levels of ER stress, the homeostatic UPR outputs activate transcriptional and translational changes that promote cellular adaptation. However, if the ER stress is irreversible despite these measures, a terminal UPR program supersedes that actively signals cell destruction. In addition to its prosurvival and prodeath outputs, the UPR is now recognized to play a major role in the differentiation and activation of specific immune cells, as well as proinflammatory cytokine production in many cell types. Given the numerous intrinsic and extrinsic factors that threaten the fidelity of the secretory pathway in cancer cells, it is not surprising that ER stress is documented in many solid and hematopoietic malignancies, but whether ongoing UPR signaling is beneficial or detrimental to tumor growth remains hotly debated. Here I review recent evidence that cancer cells are prone to loss of proteostasis within the ER, and hence may be susceptible to targeted interventions that either reduce homeostatic UPR outputs or alternatively trigger the terminal UPR.
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http://dx.doi.org/10.1152/ajpcell.00266.2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5336598PMC
February 2017

Fas-Activated Mitochondrial Apoptosis Culls Stalled Embryonic Stem Cells to Promote Differentiation.

Curr Biol 2015 Dec 12;25(23):3110-8. Epub 2015 Nov 12.

Department of Pathology, University of California, San Francisco, San Francisco, CA 94143, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA; Diabetes Center, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address:

The intrinsic (mitochondrial) apoptotic pathway is a conserved cell death program crucial for eliminating superfluous, damaged, or incorrectly specified cells, and the multi-domain pro-death BCL-2 family proteins BAX and BAK are required for its activation. In response to internal damage or developmental signals, BAX and/or BAK permeabilize the mitochondrial outer membrane, resulting in cytochrome c release and activation of effector caspases such as Caspase-3 (Casp3). While the mitochondrial apoptotic pathway plays a critical role during late embryonic development in mammals, its role during early development remains controversial. Here, we show that Bax(-/-)Bak(-/-) murine embryonic stem cells (ESCs) display defects during the exit from pluripotency, both in culture and during teratoma formation. Specifically, we find that when ESCs are stimulated to differentiate, a subpopulation fails to do so and instead upregulates FAS in a p53-dependent manner to trigger Bax/Bak-dependent apoptosis. Blocking this apoptotic pathway prevents the removal of these poorly differentiated cells, resulting in the retention of cells that have not exited pluripotency. Taken together, our results provide further evidence for heterogeneity in the potential of ESCs to successfully differentiate and reveal a novel role for apoptosis in promoting efficient ESC differentiation by culling cells that are slow to exit pluripotency.
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http://dx.doi.org/10.1016/j.cub.2015.10.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4703423PMC
December 2015

Proteostasis control by the unfolded protein response.

Nat Cell Biol 2015 Jul;17(7):829-38

Department of Pathology, Diabetes Center, and Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, California 94143, USA.

Stress induced by accumulation of misfolded proteins in the endoplasmic reticulum is observed in many physiological and pathological conditions. To cope with endoplasmic reticulum stress, cells activate the unfolded protein response, a dynamic signalling network that orchestrates the recovery of homeostasis or triggers apoptosis, depending on the level of damage. Here we provide an overview of recent insights into the mechanisms that cells employ to maintain proteostasis and how the unfolded protein response determines cell fate under endoplasmic reticulum stress.
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http://dx.doi.org/10.1038/ncb3184DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5546321PMC
July 2015

CDK1 inhibition targets the p53-NOXA-MCL1 axis, selectively kills embryonic stem cells, and prevents teratoma formation.

Stem Cell Reports 2015 Mar 26;4(3):374-89. Epub 2015 Feb 26.

Department of Cell and Tissue Biology and Medicine, University of California, San Francisco, San Francisco, CA 94143, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address:

Embryonic stem cells (ESCs) have adopted an accelerated cell-cycle program with shortened gap phases and precocious expression of cell-cycle regulatory proteins, including cyclins and cyclin-dependent kinases (CDKs). We examined the effect of CDK inhibition on the pathways regulating proliferation and survival of ESCs. We found that inhibiting cyclin-dependent kinase 1 (CDK1) leads to activation of the DNA damage response, nuclear p53 stabilization, activation of a subset of p53 target genes including NOXA, and negative regulation of the anti-apoptotic protein MCL1 in human and mouse ESCs, but not differentiated cells. We demonstrate that MCL1 is highly expressed in ESCs and loss of MCL1 leads to ESC death. Finally, we show that clinically relevant CDK1 inhibitors prevent formation of ESC-derived tumors and induce necrosis in established ESC-derived tumors. Our data demonstrate that ES cells are uniquely sensitive to CDK1 inhibition via a p53/NOXA/MCL1 pathway.
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http://dx.doi.org/10.1016/j.stemcr.2015.01.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4375943PMC
March 2015

The role of endoplasmic reticulum stress in human pathology.

Annu Rev Pathol 2015 27;10:173-94. Epub 2014 Oct 27.

Department of Pathology.

Numerous genetic and environmental insults impede the ability of cells to properly fold and posttranslationally modify secretory and transmembrane proteins in the endoplasmic reticulum (ER), leading to a buildup of misfolded proteins in this organelle--a condition called ER stress. ER-stressed cells must rapidly restore protein-folding capacity to match protein-folding demand if they are to survive. In the presence of high levels of misfolded proteins in the ER, an intracellular signaling pathway called the unfolded protein response (UPR) induces a set of transcriptional and translational events that restore ER homeostasis. However, if ER stress persists chronically at high levels, a terminal UPR program ensures that cells commit to self-destruction. Chronic ER stress and defects in UPR signaling are emerging as key contributors to a growing list of human diseases, including diabetes, neurodegeneration, and cancer. Hence, there is much interest in targeting components of the UPR as a therapeutic strategy to combat these ER stress-associated pathologies.
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http://dx.doi.org/10.1146/annurev-pathol-012513-104649DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5568783PMC
June 2015

Immune evasion mediated by tumor-derived lactate dehydrogenase induction of NKG2D ligands on myeloid cells in glioblastoma patients.

Proc Natl Acad Sci U S A 2014 Sep 18;111(35):12823-8. Epub 2014 Aug 18.

Microbiology, University of California, San Francisco, CA 94143;

Myeloid cells are key regulators of the tumor microenvironment, governing local immune responses. Here we report that tumor-infiltrating myeloid cells and circulating monocytes in patients with glioblastoma multiforme (GBM) express ligands for activating the Natural killer group 2, member D (NKG2D) receptor, which cause down-regulation of NKG2D on natural killer (NK) cells. Tumor-infiltrating NK cells isolated from GBM patients fail to lyse NKG2D ligand-expressing tumor cells. We demonstrate that lactate dehydrogenase (LDH) isoform 5 secreted by glioblastoma cells induces NKG2D ligands on monocytes isolated from healthy individuals. Furthermore, sera from GBM patients contain elevated amounts of LDH, which correlate with expression of NKG2D ligands on their autologous circulating monocytes. NKG2D ligands also are present on circulating monocytes isolated from patients with breast, prostate, and hepatitis C virus-induced hepatocellular carcinomas. Together, these findings reveal a previously unidentified immune evasion strategy whereby tumors produce soluble factors that induce NKG2D ligands on myeloid cells, subverting antitumor immune responses.
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http://dx.doi.org/10.1073/pnas.1413933111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4156766PMC
September 2014

Allosteric inhibition of the IRE1α RNase preserves cell viability and function during endoplasmic reticulum stress.

Cell 2014 Jul 10;158(3):534-48. Epub 2014 Jul 10.

Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA; Diabetes Center, University of California, San Francisco, San Francisco, CA 94143, USA; Lung Biology Center, University of California, San Francisco, San Francisco, CA 94143, USA; California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address:

Depending on endoplasmic reticulum (ER) stress levels, the ER transmembrane multidomain protein IRE1α promotes either adaptation or apoptosis. Unfolded ER proteins cause IRE1α lumenal domain homo-oligomerization, inducing trans autophosphorylation that further drives homo-oligomerization of its cytosolic kinase/endoribonuclease (RNase) domains to activate mRNA splicing of adaptive XBP1 transcription factor. However, under high/chronic ER stress, IRE1α surpasses an oligomerization threshold that expands RNase substrate repertoire to many ER-localized mRNAs, leading to apoptosis. To modulate these effects, we developed ATP-competitive IRE1α Kinase-Inhibiting RNase Attenuators-KIRAs-that allosterically inhibit IRE1α's RNase by breaking oligomers. One optimized KIRA, KIRA6, inhibits IRE1α in vivo and promotes cell survival under ER stress. Intravitreally, KIRA6 preserves photoreceptor functional viability in rat models of ER stress-induced retinal degeneration. Systemically, KIRA6 preserves pancreatic β cells, increases insulin, and reduces hyperglycemia in Akita diabetic mice. Thus, IRE1α powerfully controls cell fate but can itself be controlled with small molecules to reduce cell degeneration.
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http://dx.doi.org/10.1016/j.cell.2014.07.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4244221PMC
July 2014

Golgi fragmentation precedes neuromuscular denervation and is associated with endosome abnormalities in SOD1-ALS mouse motor neurons.

Acta Neuropathol Commun 2014 Apr 7;2:38. Epub 2014 Apr 7.

Department of Neuroscience, Erasmus Medical Center, P,O,Box 2040, 3000 CA Rotterdam, The Netherlands.

Background: Fragmentation of stacked cisterns of the Golgi apparatus into dispersed smaller elements is a feature associated with degeneration of neurons in amyotrophic lateral sclerosis (ALS) and some other neurodegenerative disorders. However, the role of Golgi fragmentation in motor neuron degeneration is not well understood.

Results: Here we use a SOD1-ALS mouse model (low-copy Gurney G93A-SOD1 mouse) to show that motor neurons with Golgi fragmentation are retrogradely labeled by intramuscularly injected CTB (beta subunit of cholera toxin), indicating that Golgi fragmentation precedes neuromuscular denervation and axon retraction. We further show that Golgi fragmentation may occur in the absence of and precede two other pathological markers, i.e. somatodendritic SOD1 inclusions, and the induction of ATF3 expression. In addition, we show that Golgi fragmentation is associated with an altered dendritic organization of the Golgi apparatus, does not depend on intact apoptotic machinery, and is facilitated in transgenic mice with impaired retrograde dynein-dependent transport (BICD2-N mice). A connection to altered dynein-dependent transport also is suggested by reduced expression of endosomal markers in neurons with Golgi fragmentation, which also occurs in neurons with impaired dynein function.

Conclusions: Together the data indicate that Golgi fragmentation is a very early event in the pathological cascade in ALS that is associated with altered organization of intracellular trafficking.
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http://dx.doi.org/10.1186/2051-5960-2-38DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4023628PMC
April 2014

Divergent allosteric control of the IRE1α endoribonuclease using kinase inhibitors.

Nat Chem Biol 2012 Dec 21;8(12):982-9. Epub 2012 Oct 21.

Department of Medicine, University of California-San Francisco, San Francisco, California, USA.

Under endoplasmic reticulum stress, unfolded protein accumulation leads to activation of the endoplasmic reticulum transmembrane kinase/endoRNase (RNase) IRE1α. IRE1α oligomerizes, autophosphorylates and initiates splicing of XBP1 mRNA, thus triggering the unfolded protein response (UPR). Here we show that IRE1α's kinase-controlled RNase can be regulated in two distinct modes with kinase inhibitors: one class of ligands occupies IRE1α's kinase ATP-binding site to activate RNase-mediated XBP1 mRNA splicing even without upstream endoplasmic reticulum stress, whereas a second class can inhibit the RNase through the same ATP-binding site, even under endoplasmic reticulum stress. Thus, alternative kinase conformations stabilized by distinct classes of ATP-competitive inhibitors can cause allosteric switching of IRE1α's RNase--either on or off. As dysregulation of the UPR has been implicated in a variety of cell degenerative and neoplastic disorders, small-molecule control over IRE1α should advance efforts to understand the UPR's role in pathophysiology and to develop drugs for endoplasmic reticulum stress-related diseases.
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http://dx.doi.org/10.1038/nchembio.1094DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3508346PMC
December 2012

IRE1α cleaves select microRNAs during ER stress to derepress translation of proapoptotic Caspase-2.

Science 2012 Nov 4;338(6108):818-22. Epub 2012 Oct 4.

Department of Pathology, University of California, San Francisco, San Francisco, CA 94143, USA.

The endoplasmic reticulum (ER) is the primary organelle for folding and maturation of secretory and transmembrane proteins. Inability to meet protein-folding demand leads to "ER stress," and activates IRE1α, an ER transmembrane kinase-endoribonuclease (RNase). IRE1α promotes adaptation through splicing Xbp1 mRNA or apoptosis through incompletely understood mechanisms. Here, we found that sustained IRE1α RNase activation caused rapid decay of select microRNAs (miRs -17, -34a, -96, and -125b) that normally repress translation of Caspase-2 mRNA, and thus sharply elevates protein levels of this initiator protease of the mitochondrial apoptotic pathway. In cell-free systems, recombinant IRE1α endonucleolytically cleaved microRNA precursors at sites distinct from DICER. Thus, IRE1α regulates translation of a proapoptotic protein through terminating microRNA biogenesis, and noncoding RNAs are part of the ER stress response.
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http://dx.doi.org/10.1126/science.1226191DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3742121PMC
November 2012

IRE1α induces thioredoxin-interacting protein to activate the NLRP3 inflammasome and promote programmed cell death under irremediable ER stress.

Cell Metab 2012 Aug;16(2):250-64

Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.

When unfolded proteins accumulate to irremediably high levels within the endoplasmic reticulum (ER), intracellular signaling pathways called the unfolded protein response (UPR) become hyperactivated to cause programmed cell death. We discovered that thioredoxin-interacting protein (TXNIP) is a critical node in this "terminal UPR." TXNIP becomes rapidly induced by IRE1α, an ER bifunctional kinase/endoribonuclease (RNase). Hyperactivated IRE1α increases TXNIP mRNA stability by reducing levels of a TXNIP destabilizing microRNA, miR-17. In turn, elevated TXNIP protein activates the NLRP3 inflammasome, causing procaspase-1 cleavage and interleukin 1β (IL-1β) secretion. Txnip gene deletion reduces pancreatic β cell death during ER stress and suppresses diabetes caused by proinsulin misfolding in the Akita mouse. Finally, small molecule IRE1α RNase inhibitors suppress TXNIP production to block IL-1β secretion. In summary, the IRE1α-TXNIP pathway is used in the terminal UPR to promote sterile inflammation and programmed cell death and may be targeted to develop effective treatments for cell degenerative diseases.
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http://dx.doi.org/10.1016/j.cmet.2012.07.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4014071PMC
August 2012

Dual blockade of lipid and cyclin-dependent kinases induces synthetic lethality in malignant glioma.

Proc Natl Acad Sci U S A 2012 Jul 16;109(31):12722-7. Epub 2012 Jul 16.

Department of Neurology, Dana Farber Cancer Institute, Boston, MA 02115, USA.

Malignant glioma, the most common primary brain tumor, is generally incurable. Although phosphatidylinositol-3-kinase (PI3K) signaling features prominently in glioma, inhibitors generally block proliferation rather than induce apoptosis. Starting with an inhibitor of both lipid and protein kinases that induced prominent apoptosis and that failed early clinical development because of its broad target profile and overall toxicity, we identified protein kinase targets, the blockade of which showed selective synthetic lethality when combined with PI3K inhibitors. Prioritizing protein kinase targets for which there are clinical inhibitors, we demonstrate that cyclin-dependent kinase (CDK)1/2 inhibitors, siRNAs against CDK1/2, and the clinical CDK1/2 inhibitor roscovitine all cooperated with the PI3K inhibitor PIK-90, blocking the antiapoptotic protein Survivin and driving cell death. In addition, overexpression of CDKs partially blocked some of the apoptosis caused by PIK-75. Roscovitine and PIK-90, in combination, were well tolerated in vivo and acted in a synthetic-lethal manner to induce apoptosis in human glioblastoma xenografts. We also tested clinical Akt and CDK inhibitors, demonstrating induction of apoptosis in vitro and providing a preclinical rationale to test this combination therapy in patients.
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http://dx.doi.org/10.1073/pnas.1202492109DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3411950PMC
July 2012

The adaptor protein CRK is a pro-apoptotic transducer of endoplasmic reticulum stress.

Nat Cell Biol 2011 Dec 18;14(1):87-92. Epub 2011 Dec 18.

Department of Pathology, University of California-San Francisco, San Francisco, California 94143-0511, USA.

Excessive demands on the protein-folding capacity of the endoplasmic reticulum (ER) cause irremediable ER stress and contribute to cell loss in a number of cell degenerative diseases, including type 2 diabetes and neurodegeneration. The signals communicating catastrophic ER damage to the mitochondrial apoptotic machinery remain poorly understood. We used a biochemical approach to purify a cytosolic activity induced by ER stress that causes release of cytochrome c from isolated mitochondria. We discovered that the principal component of the purified pro-apoptotic activity is the proto-oncoprotein CRK (CT10-regulated kinase), an adaptor protein with no known catalytic activity. Crk(-/-) cells are strongly resistant to ER-stress-induced apoptosis. Moreover, CRK is cleaved in response to ER stress to generate an amino-terminal M(r)~14K fragment with greatly enhanced cytotoxic potential. We identified a putative BH3 (BCL2 homology 3) domain within this N-terminal CRK fragment, which sensitizes isolated mitochondria to cytochrome c release and when mutated significantly reduces the apoptotic activity of CRK in vivo. Together these results identify CRK as a pro-apoptotic protein that signals irremediable ER stress to the mitochondrial execution machinery.
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http://dx.doi.org/10.1038/ncb2395DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3245775PMC
December 2011

Multiple defects, including premature apoptosis, prevent Kaposi's sarcoma-associated herpesvirus replication in murine cells.

J Virol 2012 Feb 30;86(3):1877-82. Epub 2011 Nov 30.

Howard Hughes Medical Institute and G. W. Hooper Foundation, Departments of Microbiology and Medicine, University of California, San Francisco, California, USA.

The development of a mouse model for Kaposi's sarcoma-associated herpesvirus (KSHV) infection has been impeded by the limited host range of the virus. Here, we have examined the molecular basis of this host range restriction. KSHV efficiently enters murine cells and establishes latency. However, ectopic expression of the lytic switch protein RTA (replication and transcription activator) in these cells induces little viral gene expression and no virus production. Upon treatment with histone deacetylase inhibitors, KSHV-infected murine cells display more extensive but aberrant viral transcription and do not support either viral DNA synthesis or the production of infectious virions. These aberrantly infected cells also display markedly enhanced apoptosis. Genetic ablation of the mitochondrial apoptotic pathway in these cells prolongs their survival and permits viral DNA replication but does not rescue the generation of virions. We conclude that multiple defects, both prior to and following DNA synthesis, restrict lytic KSHV infection in murine cells.
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http://dx.doi.org/10.1128/JVI.06600-11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3264352PMC
February 2012

Signaling cell death from the endoplasmic reticulum stress response.

Curr Opin Cell Biol 2011 Apr 9;23(2):143-9. Epub 2010 Dec 9.

Department of Biochemistry and Goodman Cancer Center, McGill University, Montreal, Quebec, H3G 1Y6, Canada.

Inability to meet protein folding demands within the endoplasmic reticulum (ER) activates the unfolded protein response (UPR), a signaling pathway with both adaptive and apoptotic outputs. While some secretory cell types have a remarkable ability to increase protein folding capacity, their upper limits can be reached when pathological conditions overwhelm the fidelity and/or output of the secretory pathway. Irremediable 'ER stress' induces apoptosis and contributes to cell loss in several common human diseases, including type 2 diabetes and neurodegeneration. Researchers have begun to elucidate the molecular switches that determine when ER stress is too great to repair and the signals that are then sent from the UPR to execute the cell.
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http://dx.doi.org/10.1016/j.ceb.2010.11.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3078187PMC
April 2011

Akt and autophagy cooperate to promote survival of drug-resistant glioma.

Sci Signal 2010 Nov 9;3(147):ra81. Epub 2010 Nov 9.

Department of Neurology, University of California, 1450 Third Street, MC0520, San Francisco, CA 94158-9001, USA.

Although the phosphatidylinositol 3-kinase to Akt to mammalian target of rapamycin (PI3K-Akt-mTOR) pathway promotes survival signaling, inhibitors of PI3K and mTOR induce minimal cell death in PTEN (phosphatase and tensin homolog deleted from chromosome 10) mutant glioma. Here, we show that the dual PI3K-mTOR inhibitor PI-103 induces autophagy in a form of glioma that is resistant to therapy. Inhibitors of autophagosome maturation cooperated with PI-103 to induce apoptosis through the mitochondrial pathway, indicating that the cellular self-digestion process of autophagy acted as a survival signal in this setting. Not all inhibitors of mTOR synergized with inhibitors of autophagy. Rapamycin delivered alone induced autophagy, yet cells survived inhibition of autophagosome maturation because of rapamycin-mediated activation of Akt. In contrast, adenosine 5'-triphosphate-competitive inhibitors of mTOR stimulated autophagy more potently than did rapamycin, with inhibition of mTOR complexes 1 and 2 contributing independently to induction of autophagy. We show that combined inhibition of PI3K and mTOR, which activates autophagy without activating Akt, cooperated with inhibition of autophagy to cause glioma cells to undergo apoptosis. Moreover, the PI3K-mTOR inhibitor NVP-BEZ235, which is in clinical use, synergized with the lysosomotropic inhibitor of autophagy, chloroquine, another agent in clinical use, to induce apoptosis in glioma xenografts in vivo, providing a therapeutic approach potentially translatable to humans.
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http://dx.doi.org/10.1126/scisignal.2001017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3001107PMC
November 2010

Blocking the mitochondrial apoptotic pathway preserves motor neuron viability and function in a mouse model of amyotrophic lateral sclerosis.

J Clin Invest 2010 Oct 20;120(10):3673-9. Epub 2010 Sep 20.

Department of Pathology, University of California, San Francisco, San Francisco, California 94143-0511, USA.

Apoptosis of motor neurons is a well-documented feature in amyotrophic lateral sclerosis (ALS) and related motor neuron diseases (MNDs). However, the role of apoptosis in the pathogenesis of these diseases remains unresolved. One possibility is that the affected motor neurons only succumb to apoptosis once they have exhausted functional capacity. If true, blocking apoptosis should confer no therapeutic benefit. To directly investigate this idea, we tested whether tissue-specific deletion in the mouse CNS of BCL2-associated X protein (BAX) and BCL2-homologous antagonist/killer (BAK), 2 proapoptotic BCL-2 family proteins that together represent an essential gateway to the mitochondrial apoptotic pathway, would protect against motor neuron degeneration. We found that neuronal deletion of Bax and Bak in a mouse model of familial ALS not only halted neuronal loss, but prevented axonal degeneration, symptom onset, weight loss, and paralysis and extended survival. These results show that motor neurons damaged in ALS activate the mitochondrial apoptotic pathway early in the disease process and that apoptotic signaling directly contributes to neuromuscular degeneration and neuronal dysfunction. Hence, inhibiting apoptosis upstream of mitochondrial permeabilization represents a possible therapeutic strategy for preserving functional motor neurons in ALS and other MNDs.
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http://dx.doi.org/10.1172/JCI42986DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2947232PMC
October 2010

IRE1alpha kinase activation modes control alternate endoribonuclease outputs to determine divergent cell fates.

Cell 2009 Aug;138(3):562-75

Department of Medicine, University of California, San Francisco, San Francisco, CA 94143-2520, USA.

During endoplasmic reticulum (ER) stress, homeostatic signaling through the unfolded protein response (UPR) augments ER protein-folding capacity. If homeostasis is not restored, the UPR triggers apoptosis. We found that the ER transmembrane kinase/endoribonuclease (RNase) IRE1alpha is a key component of this apoptotic switch. ER stress induces IRE1alpha kinase autophosphorylation, activating the RNase to splice XBP1 mRNA and produce the homeostatic transcription factor XBP1s. Under ER stress--or forced autophosphorylation--IRE1alpha's RNase also causes endonucleolytic decay of many ER-localized mRNAs, including those encoding chaperones, as early events culminating in apoptosis. Using chemical genetics, we show that kinase inhibitors bypass autophosphorylation to activate the RNase by an alternate mode that enforces XBP1 splicing and averts mRNA decay and apoptosis. Alternate RNase activation by kinase-inhibited IRE1alpha can be reconstituted in vitro. We propose that divergent cell fates during ER stress hinge on a balance between IRE1alpha RNase outputs that can be tilted with kinase inhibitors to favor survival.
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http://dx.doi.org/10.1016/j.cell.2009.07.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2762408PMC
August 2009

Caspase-2 cleavage of BID is a critical apoptotic signal downstream of endoplasmic reticulum stress.

Mol Cell Biol 2008 Jun 21;28(12):3943-51. Epub 2008 Apr 21.

Department of Pathology, Medicine, University of California, San Francisco, California 94143, USA.

The accumulation of misfolded proteins stresses the endoplasmic reticulum (ER) and triggers cell death through activation of the multidomain proapoptotic BCL-2 proteins BAX and BAK at the outer mitochondrial membrane. The signaling events that connect ER stress with the mitochondrial apoptotic machinery remain unclear, despite evidence that deregulation of this pathway contributes to cell loss in many human degenerative diseases. In order to "trap" and identify the apoptotic signals upstream of mitochondrial permeabilization, we challenged Bax-/- Bak-/- mouse embryonic fibroblasts with pharmacological inducers of ER stress. We found that ER stress induces proteolytic activation of the BH3-only protein BID as a critical apoptotic switch. Moreover, we identified caspase-2 as the premitochondrial protease that cleaves BID in response to ER stress and showed that resistance to ER stress-induced apoptosis can be conferred by inhibiting caspase-2 activity. Our work defines a novel signaling pathway that couples the ER and mitochondria and establishes a principal apoptotic effector downstream of ER stress.
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http://dx.doi.org/10.1128/MCB.00013-08DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2423129PMC
June 2008

A kinase inhibitor activates the IRE1alpha RNase to confer cytoprotection against ER stress.

Biochem Biophys Res Commun 2008 Jan 21;365(4):777-83. Epub 2007 Nov 21.

Department of Medicine, University of California, San Francisco, San Francisco, CA 94143-2520, USA.

Unfolded proteins in the endoplasmic reticulum (ER) cause trans-autophosphorylation of the bifunctional transmembrane kinase IRE1alpha, inducing its RNase activity to splice XBP1 mRNA, in turn triggering a transcriptional program in the unfolded protein response (UPR). As we previously showed with the yeast IRE1 kinase ortholog, a single missense mutation in the ATP-binding pocket of murine IRE1alpha kinase sensitizes it to the ATP-competitive inhibitor 1NM-PP1, and subordinates RNase activity to the drug. This highly unusual mechanism of kinase signaling requiring kinase domain ligand occupancy-even through an inhibitor-to activate a nearby RNase has therefore been completely conserved through evolution. We also demonstrate that engagement of the drug-sensitized IRE1alpha kinase through this maneuver affords murine cells cytoprotection under ER stress. Thus kinase inhibitors of IRE1alpha are useful for altering the apoptotic outcome to ER stress, and could possibly be developed into drugs to treat ER stress-related diseases.
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http://dx.doi.org/10.1016/j.bbrc.2007.11.040DOI Listing
January 2008

Mitochondria control calcium entry at the immunological synapse.

Authors:
Scott A Oakes

Proc Natl Acad Sci U S A 2007 Sep 19;104(39):15171-2. Epub 2007 Sep 19.

Department of Pathology, University of California, San Francisco, CA 94143-0511, USA.

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http://dx.doi.org/10.1073/pnas.0707798104DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2000514PMC
September 2007

The control of endoplasmic reticulum-initiated apoptosis by the BCL-2 family of proteins.

Curr Mol Med 2006 Feb;6(1):99-109

Department of Pathology, University of California, San Francisco, 94143, USA.

Irreversible perturbations in the homeostasis of the endoplasmic reticulum (ER) are thought to lead to apoptosis and cell loss in a number of important human diseases, including Alzheimer disease, Parkinson disease, and type 2 diabetes. However, the exact mechanisms that lead from ER stress to cell death remain incompletely understood. Recent work has shown that the BCL-2 family of proteins plays a central role in regulating this form of cell death, both locally at the ER and from a distance at the mitochondrial membrane.
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http://dx.doi.org/10.2174/156652406775574587DOI Listing
February 2006