JAK/STAT inhibitor therapy partially rescues the lipodystrophic autoimmune phenotype in Clec16a KO mice

AbstractCLEC16A is implicated in multiple autoimmune diseases. We generated an inducible whole-body knockout (KO), Clec16aΔUBC mice to address the role of CLEC16A loss of function. KO mice exhibited loss of adipose tissue and severe weight loss in response to defective autophagic flux and exaggerated endoplasmic reticulum (ER) stress and robust cytokine storm. KO mice were glucose tolerant and displayed a state of systemic inflammation with elevated antibody levels, including IgM, IgA, Ig2b and IgG3, significantly reduced circulating insulin levels in the presence of normal food consumption. Metabolic analysis revealed disturbances in the lipid profile, white adipose decreasing concomitantly with enhanced inflammatory response, and energy wasting. Mechanistically, endoplasmic reticulum (ER) stress triggers excessive hormone sensitive lipases (HSL) mediated lipolysis which contributes to adipose inflammation via activation of JAK-STAT, stress kinases (ERK1/2, P38, JNK), and release of multiple proinflammatory mediators. Treatment with a JAK-STAT inhibitor (tofacitinib) partially rescued the inflammatory lipodystrophic phenotype and improved survival of Clec16aΔUBC mice by silencing cytokine release and modulating ER stress, lipolysis, mitophagy and autophagy. These results establish a mechanistic link between CLEC16A, lipid metabolism and the immune system perturbations. In summary, our Clec16aΔUBC mouse model highlights multifaceted roles of Clec16a in normal physiology, including a novel target for weight regulation and mutation-induced pathophysiology.

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Acute Tissue Injury Caused by Subcutaneous Fat Biopsies Produces Endoplasmic Reticulum Stress

Endocrine Reviews ◽

10.1210/edrv.30.7.9995 ◽

2009 ◽

Vol 30 (7) ◽

pp. 928-928

Author(s):

Guenther Boden ◽

Matthew Silviera ◽

Brian Smith ◽

Peter Cheung ◽

Carol Homko

Keyword(s):

Endoplasmic Reticulum ◽

Er Stress ◽

Tissue Injury ◽

Subcutaneous Fat ◽

Whole Body ◽

Monocyte Chemoattractant Protein 1 ◽

Homologous Protein ◽

Stress Markers ◽

Acute Tissue Injury ◽

Glucose Regulated Protein

Abstract Background It is not known whether acute tissue injury is associated with endoplasmic reticulum (ER) stress. Objective Our objective was to determine whether open, sc fat biopsies cause ER stress. Approach Five healthy subjects underwent three open sc fat biopsies. The first biopsy, taken from the lateral aspect of a thigh, was followed 4 h later by a second biopsy from the same incision site and a third biopsy from the contralateral leg. Expression markers of ER stress, inflammation, hypoxia, and adipokines were measured in these fat biopsies. In addition, we tested for signs of systemic ER stress and inflammation in plasma and in circulating monocytes. Results mRNA/18s ratios of IL-6, monocyte chemoattractant protein-1, CD-14, hypoxia-induced factor 1-α, the spliced form of Xbox protein-1, glucose-regulated protein 78, CEBP homologous protein, and activating factor-4 were all severalfold higher, whereas mRNA/18s ratios of adiponectin and leptin were lower in fat biopsies taken from the same site 4 h after the first biopsy but were unchanged in the second biopsy that was taken from the contralateral site. The biopsies were not associated with changes in plasma and monocyte IL-6 concentrations or in monocyte ER stress markers. Also, whole-body insulin-stimulated glucose uptake was the same in 15 subjects who had biopsies compared with 15 different subjects who did not. Conclusion Open, sc fat biopsies produced inflammation, hypoxia, ER stress, and decreased expression of adiponectin and leptin. These changes remained confined to the biopsy site for at least 4 h.

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Development of a pH-responsive polymersome inducing endoplasmic reticulum stress and autophagy blockade

Science Advances ◽

10.1126/sciadv.abb8725 ◽

2020 ◽

Vol 6 (31) ◽

pp. eabb8725 ◽

Cited By ~ 2

Author(s):

Funeng Xu ◽

Xilin Li ◽

Xuehui Huang ◽

Jingmei Pan ◽

Yi Wang ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Er Stress ◽

Tumor Metastasis ◽

Focal Adhesions ◽

Matrix Metalloproteinase 2 ◽

Autophagic Flux ◽

Ph Responsive ◽

Ph Response ◽

Function Mechanism ◽

Inhibit Tumor Metastasis

Autophagy is involved in the occurrence and development of tumors. Here, a pH-responsive polymersome codelivering hydroxychloroquine (HCQ) and tunicamycin (Tuni) drugs is developed to simultaneously induce endoplasmic reticulum (ER) stress and autophagic flux blockade for achieving an antitumor effect and inhibiting tumor metastasis. The pH response of poly(β-amino ester) and HCQ synergistically deacidifies the lysosomes, thereby blocking the fusion of autophagosomes and lysosomes and lastly blocking autophagic flux. The function mechanism of regulating autophagy was systematically investigated on orthotopic luciferase gene–transfected, 4T1 tumor–bearing BALB/c mice through Western blot and immunohistochemistry analyses. The Tuni triggers ER stress to regulate the PERK/Akt signaling pathway to increase the autophagic level. The “autophagic stress” generated by triggering ER stress–induced autophagy and blocking autophagic flux is effective against tumors. The reduced expression of matrix metalloproteinase-2 due to ER stress and reduced focal adhesions turnover due to the blockade of autophagic flux synergistically inhibit tumor metastasis.

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Deficiency in the double-stranded RNA binding protein HYPONASTIC LEAVES1 increases sensitivity to the endoplasmic reticulum stress inducer tunicamycin in Arabidopsis

BMC Research Notes ◽

10.1186/s13104-019-4623-3 ◽

2019 ◽

Vol 12 (1) ◽

Author(s):

Rikako Hirata ◽

Kei-ichiro Mishiba ◽

Nozomu Koizumi ◽

Yuji Iwata

Keyword(s):

Endoplasmic Reticulum ◽

Er Stress ◽

Stress Responses ◽

Rna Binding ◽

Transcriptional Response ◽

Mirna Biogenesis ◽

Loss Of Function ◽

Wild Type ◽

Protein Coding ◽

And Function

Abstract Objective microRNA (miRNA) is a small non-coding RNA that regulates gene expression by sequence-dependent binding to protein-coding mRNA in eukaryotic cells. In plants, miRNA plays important roles in a plethora of physiological processes, including abiotic and biotic stress responses. The present study was conducted to investigate whether miRNA-mediated regulation is important for the endoplasmic reticulum (ER) stress response in Arabidopsis. Results We found that hyl1 mutant plants are more sensitive to tunicamycin, an inhibitor of N-linked glycosylation that causes ER stress than wild-type plants. Other miRNA-related mutants, se and ago1, exhibited similar sensitivity to the wild-type, indicating that the hypersensitive phenotype is attributable to the loss-of-function of HYL1, rather than deficiency in general miRNA biogenesis and function. However, the transcriptional response of select ER stress-responsive genes in hyl1 mutant plants was indistinguishable from that of wild-type plants, suggesting that the loss-of-function of HYL1 does not affect the ER stress signaling pathways.

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A crucial role for Jagunal homolog 1 in humoral immunity and antibody glycosylation in mice and humans

Journal of Experimental Medicine ◽

10.1084/jem.20200559 ◽

2020 ◽

Vol 218 (1) ◽

Author(s):

Astrid Hagelkruys ◽

Gerald Wirnsberger ◽

Johannes Stadlmann ◽

Miriam Wöhner ◽

Marion Horrer ◽

...

Keyword(s):

Immune Response ◽

Endoplasmic Reticulum ◽

B Cells ◽

Er Stress ◽

Rare Disease ◽

Humoral Immunity ◽

Viral Infections ◽

Loss Of Function ◽

Humoral Immune ◽

Specific Antigens

Jagunal homolog 1 (JAGN1) has been identified as a critical regulator of neutrophil biology in mutant mice and rare-disease patients carrying JAGN1 mutations. Here, we report that Jagn1 deficiency results in alterations in the endoplasmic reticulum (ER) of antibody-producing cells as well as decreased antibody production and secretion. Consequently, mice lacking Jagn1 in B cells exhibit reduced serum immunoglobulin (Ig) levels at steady state and fail to mount an efficient humoral immune response upon immunization with specific antigens or when challenged with viral infections. We also demonstrate that Jagn1 deficiency in B cells results in aberrant IgG N-glycosylation leading to enhanced Fc receptor binding. Jagn1 deficiency in particular affects fucosylation of IgG subtypes in mice as well as rare-disease patients with loss-of-function mutations in JAGN1. Moreover, we show that ER stress affects antibody glycosylation. Our data uncover a novel and key role for JAGN1 and ER stress in antibody glycosylation and humoral immunity in mice and humans.

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Deficiency of selenoprotein S, an endoplasmic reticulum resident oxidoreductase, impairs the contractile function of fast-twitch hindlimb muscles

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00244.2017 ◽

2018 ◽

Vol 315 (2) ◽

pp. R380-R396 ◽

Cited By ~ 5

Author(s):

Alex B. Addinsall ◽

Craig R. Wright ◽

Chris S. Shaw ◽

Natasha L. McRae ◽

Leonard G. Forgan ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Er Stress ◽

Knockout Mice ◽

Contractile Function ◽

Whole Body ◽

Force Frequency ◽

Wild Type ◽

Selenoprotein S ◽

Hindlimb Muscles ◽

Fast Twitch

Selenoprotein S (Seps1) is an endoplasmic reticulum (ER) resident antioxidant implicated in ER stress and inflammation. In human vastus lateralis and mouse hindlimb muscles, Seps1 localization and expression were fiber-type specific. In male Seps1+/− heterozygous mice, spontaneous physical activity was reduced compared with wild-type littermates ( d = 1.10, P = 0.029). A similar trend was also observed in Seps1−/− knockout mice ( d = 1.12, P = 0.051). Whole body metabolism, body composition, extensor digitorum longus (EDL), and soleus mass and myofiber diameter were unaffected by genotype. However, in isolated fast EDL muscles from Seps1−/− knockout mice, the force frequency curve (FFC; 1–120 Hz) was shifted downward versus EDL muscles from wild-type littermates ( d = 0.55, P = 0.002), suggestive of reduced strength. During 4 min of intermittent, submaximal (60 Hz) stimulation, the genetic deletion or reduction of Seps1 decreased EDL force production ( d = 0.52, P < 0.001). Furthermore, at the start of the intermittent stimulation protocol, when compared with the 60-Hz stimulation of the FFC, EDL muscles from Seps1−/− knockout or Seps1+/− heterozygous mice produced 10% less force than those from wild-type littermates ( d = 0.31, P < 0.001 and d = 0.39, P = 0.015). This functional impairment was associated with reduced mRNA transcript abundance of thioredoxin-1 ( Trx1), thioredoxin interacting protein ( Txnip), and the ER stress markers Chop and Grp94, whereas, in slow soleus muscles, Seps1 deletion did not compromise contractile function and Trx1 ( d = 1.38, P = 0.012) and Txnip ( d = 1.27, P = 0.025) gene expression was increased. Seps1 is a novel regulator of contractile function and cellular stress responses in fast-twitch muscles.

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FoxO suppresses endoplasmic reticulum stress to inhibit growth of Tsc1-deficient tissues under nutrient restriction

eLife ◽

10.7554/elife.53159 ◽

2020 ◽

Vol 9 ◽

Author(s):

Avantika Gupta ◽

Hugo Stocker

Keyword(s):

Endoplasmic Reticulum ◽

Er Stress ◽

Target Genes ◽

Degradation Pathway ◽

Nutrient Restriction ◽

Loss Of Function ◽

Er Stress Response ◽

Stress Markers ◽

Stress Response Pathway ◽

Elevated Expression

The transcription factor FoxO has been shown to block proliferation and progression in mTORC1-driven tumorigenesis but the picture of the relevant FoxO target genes remains incomplete. Here, we employed RNA-seq profiling on single clones isolated using laser capture microdissection from Drosophila larval eye imaginal discs to identify FoxO targets that restrict the proliferation of Tsc1-deficient cells under nutrient restriction (NR). Transcriptomics analysis revealed downregulation of endoplasmic reticulum-associated protein degradation pathway components upon foxo knockdown. Induction of ER stress pharmacologically or by suppression of other ER stress response pathway components led to an enhanced overgrowth of Tsc1 knockdown tissue. Increase of ER stress in Tsc1 loss-of-function cells upon foxo knockdown was also confirmed by elevated expression levels of known ER stress markers. These results highlight the role of FoxO in limiting ER stress to regulate Tsc1 mutant overgrowth.

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Reticulon proteins modulate autophagy of the endoplasmic reticulum in maize endosperm

eLife ◽

10.7554/elife.51918 ◽

2020 ◽

Vol 9 ◽

Cited By ~ 7

Author(s):

Xiaoguo Zhang ◽

Xinxin Ding ◽

Richard Scott Marshall ◽

Julio Paez-Valencia ◽

Patrick Lacey ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Er Stress ◽

Lipid Droplets ◽

Autophagic Flux ◽

Dependent Manner ◽

Maize Endosperm ◽

Transmembrane Segments ◽

C Terminus ◽

Er Homeostasis ◽

Dose Dependent

Reticulon (Rtn) proteins shape tubular domains of the endoplasmic reticulum (ER), and in some cases are autophagy receptors for selective ER turnover. We have found that maize Rtn1 and Rtn2 control ER homeostasis and autophagic flux in endosperm aleurone cells, where the ER accumulates lipid droplets and synthesizes storage protein accretions metabolized during germination. Maize Rtn1 and Rtn2 are expressed in the endosperm, localize to the ER, and re-model ER architecture in a dose-dependent manner. Rtn1 and Rtn2 interact with Atg8a using four Atg8-interacting motifs (AIMs) located at the C-terminus, cytoplasmic loop, and within the transmembrane segments. Binding between Rtn2 and Atg8 is elevated upon ER stress. Maize rtn2 mutants display increased autophagy and up-regulation of an ER stress-responsive chaperone. We propose that maize Rtn1 and Rtn2 act as receptors for autophagy-mediated ER turnover, and thus are critical for ER homeostasis and suppression of ER stress.

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Role of ERO1-α–mediated stimulation of inositol 1,4,5-triphosphate receptor activity in endoplasmic reticulum stress–induced apoptosis

The Journal of Cell Biology ◽

10.1083/jcb.200904060 ◽

2009 ◽

Vol 186 (6) ◽

pp. 783-792 ◽

Cited By ~ 326

Author(s):

Gang Li ◽

Marco Mongillo ◽

King-Tung Chin ◽

Heather Harding ◽

David Ron ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Er Stress ◽

Calcium Release ◽

Loss Of Function ◽

Ip3 Receptor ◽

Calcium Dependent ◽

Insulin Resistant ◽

Stressed Cells ◽

Induced Apoptosis

Endoplasmic reticulum (ER) stress–induced apoptosis is involved in many diseases, but the mechanisms linking ER stress to apoptosis are incompletely understood. Based on roles for C/EPB homologous protein (CHOP) and ER calcium release in apoptosis, we hypothesized that apoptosis involves the activation of inositol 1,4,5-triphosphate (IP3) receptor (IP3R) via CHOP-induced ERO1-α (ER oxidase 1 α). In ER-stressed cells, ERO1-α is induced by CHOP, and small interfering RNA (siRNA) knockdown of ERO1-α suppresses apoptosis. IP3-induced calcium release (IICR) is increased during ER stress, and this response is blocked by siRNA-mediated silencing of ERO1-α or IP3R1 and by loss-of-function mutations in Ero1a or Chop. Reconstitution of ERO1-α in Chop−/− macrophages restores ER stress–induced IICR and apoptosis. In vivo, macrophages from wild-type mice but not Chop−/− mice have elevated IICR when the animals are challenged with the ER stressor tunicamycin. Macrophages from insulin-resistant ob/ob mice, another model of ER stress, also have elevated IICR. These data shed new light on how the CHOP pathway of apoptosis triggers calcium-dependent apoptosis through an ERO1-α–IP3R pathway.

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Endoplasmic Reticulum Stress-Related Inflammation and Cardiovascular Diseases

International Journal of Inflammation ◽

10.4061/2011/259462 ◽

2011 ◽

Vol 2011 ◽

pp. 1-8 ◽

Cited By ~ 57

Author(s):

Tomomi Gotoh ◽

Motoyoshi Endo ◽

Yuichi Oike

Keyword(s):

Endoplasmic Reticulum ◽

Stress Response ◽

Cardiovascular Diseases ◽

Inflammatory Response ◽

Er Stress ◽

Er Stress Response ◽

Stress Response Pathway ◽

Apoptosis Pathways ◽

Novel Target ◽

Stress Pathway

The endoplasmic reticulum (ER) is the site of synthesis and maturation of proteins designed for secretion or for localization on the cell membrane. Various types of stress from both inside and outside cells disturb ER function, thus causing unfolded or misfolded proteins to accumulate in the ER. To improve and maintain the ER functions against such stresses, the ER stress response pathway is activated. However, when the stress is prolonged or severe, apoptosis pathways are activated to remove damaged cells. It was recently reported that the ER stress pathway is also involved in the inflammatory response, whereby inflammation induces ER stress, and ER stress induces an inflammatory response. Therefore, the ER stress response pathway is involved in various diseases, including cardiovascular diseases such as atherosclerosis and ischemic diseases, in various ways. The ER stress pathway may represent a novel target for the treatment of these diseases.

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Endoplasmic Reticulum Stress Disturbs Lipid Homeostasis and Augments Inflammation in the Intestine and Isolated Intestinal Cells of Large Yellow Croaker (Larimichthys crocea)

Frontiers in Immunology ◽

10.3389/fimmu.2021.738143 ◽

2021 ◽

Vol 12 ◽

Author(s):

Wei Fang ◽

Qiuchi Chen ◽

Jiamin Li ◽

Yongtao Liu ◽

Zengqi Zhao ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Lipid Metabolism ◽

Er Stress ◽

Lipid Synthesis ◽

Whole Body ◽

Lipid Homeostasis ◽

Intestinal Cells ◽

Large Yellow Croaker ◽

Human Beings ◽

Larimichthys Crocea

The small intestine is crucial for lipid homeostasis and immune regulation of the whole body. Endoplasmic reticulum (ER) stress may affect lipid metabolism and inflammation in the intestine, but the potential mechanism is not completely understood. In the present study, intraperitoneal injection of tunicamycin (TM) induced ER stress in the intestine of large yellow croaker (Larimichthys crocea). ER stress induced excessive accumulation of triglyceride (TG) in the intestine by promoting lipid synthesis. However, it also enhanced lipid secretion and fatty acid β-oxidation. In addition, ER stress augmented inflammation in the intestine by promoting p65 into the nucleus and increasing proinflammatory genes expression. In the isolated intestinal cells, the obtained results showed that TM treatment significantly upregulated the mRNA expression of lipid synthesis and inflammatory response genes, which were consistent with those in vivo. Moreover, overexpression of unfolded protein response (UPR) sensors significantly upregulated promoter activities of lipid synthesis and proinflammatory genes. In conclusion, the results suggested that ER stress disturbed lipid metabolism and augmented inflammation in the intestine and isolated intestinal cells of large yellow croaker, which may contribute to finding novel therapies to tackle lipid dysregulation and inflammation in the intestine of fish and human beings.

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