Misregulation of ER-Golgi Vesicle Transport Induces ER Stress and Affects Seed Vigor and Stress Response

Post-translational modification with Ubiquitin-like proteins represents a complex signaling language regulating virtually every cellular process. Among these post-translational modifiers is Ubiquitin-fold modifier (UFM1), which is covalently attached to its substrates through the orchestrated action of a dedicated enzymatic cascade. Originally identified to be involved embryonic development, its biological function remains enigmatic. Recent research reveals that UFM1 regulates a variety of cellular events ranging from DNA repair to autophagy and ER stress response implicating its involvement in a variety of diseases. Given the contribution of UFM1 to numerous pathologies, the enzymes of the UFM1 cascade represent attractive targets for pharmacological inhibition. Here we discuss the current understanding of this cryptic post-translational modification especially its contribution to disease as well as expand on the unmet needs of developing chemical and biochemical tools to dissect its role.

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Activation of endoplasmic reticulum stress response during the development of ischemic heart disease

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01378.2005 ◽

2006 ◽

Vol 291 (3) ◽

pp. H1411-H1420 ◽

Cited By ~ 157

Author(s):

Asim Azfer ◽

Jianli Niu ◽

Linda M. Rogers ◽

Frances M. Adamski ◽

Pappachan E. Kolattukudy

Keyword(s):

Endoplasmic Reticulum ◽

Heart Disease ◽

Stress Response ◽

Transgenic Mice ◽

Ischemic Heart Disease ◽

Er Stress ◽

Stress Proteins ◽

Gene Array ◽

Ischemic Heart ◽

Endoplasmic Reticulum Stress Response

Endoplasmic reticulum (ER) stress has been found to be associated with neurodegenerative diseases and diabetes mellitus. Whether ER stress is involved in the development of heart disease is not known. Cardiac-specific expression of monocyte chemoattractant protein-1 (MCP-1) in mice causes the development of ischemic heart disease. Here we report that microarray analysis of gene expression changes in the heart of these transgenic mice revealed that a cluster of ER stress-related genes was transcriptionally activated in the heart during the development of ischemic heart disease. The gene array results were verified by quantitative real-time PCR that showed highly elevated transcript levels of genes involved in unfolded protein response such as ER and cytoplasmic chaperones, oxidoreductases, protein disulfide isomerase (PDI) family, and ER-associated degradation system such as ubiquitin. Immunoblot analysis confirmed the expression of chaperones, PDI, and ubiquitin. Immunohistochemical analyses showed that ER stress proteins were associated mainly with the degenerating cardiomyocytes. A novel ubiquitin fold modifier (Ufm1) that has not been previously associated with ER stress and not found to be induced under any condition was also found to be upregulated in the hearts of MCP mice (transgenic mice that express MCP-1 specifically in the heart). The present results strongly suggest that activation of ER stress response is involved in the development of ischemic heart disease in this murine model.

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12/15-Lipoxygenase signaling in the endoplasmic reticulum stress response

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00373.2011 ◽

2012 ◽

Vol 302 (6) ◽

pp. E654-E665 ◽

Cited By ~ 35

Author(s):

Banumathi K. Cole ◽

Norine S. Kuhn ◽

Shamina M. Green-Mitchell ◽

Kendall A. Leone ◽

Rebekah M. Raab ◽

...

Keyword(s):

Insulin Resistance ◽

Endoplasmic Reticulum ◽

Stress Response ◽

Er Stress ◽

Pancreatic Islets ◽

High Fat Diet ◽

Wild Type ◽

High Fat ◽

Stress Markers ◽

Deficient Mice

Central obesity is associated with chronic inflammation, insulin resistance, β-cell dysfunction, and endoplasmic reticulum (ER) stress. The 12/15-lipoxygenase enzyme (12/15-LO) promotes inflammation and insulin resistance in adipose and peripheral tissues. Given that obesity is associated with ER stress and 12/15-LO is expressed in adipose tissue, we determined whether 12/15-LO could mediate ER stress signals. Addition of 12/15-LO lipid products 12(S)-HETE and 12(S)-HPETE to differentiated 3T3-L1 adipocytes induced expression and activation of ER stress markers, including BiP, XBP-1, p-PERK, and p-IRE1α. The ER stress inducer, tunicamycin, upregulated ER stress markers in adipocytes with concomitant 12/15-LO activation. Addition of a 12/15-LO inhibitor, CDC, to tunicamycin-treated adipocytes attenuated the ER stress response. Furthermore, 12/15-LO-deficient adipocytes exhibited significantly decreased tunicamycin-induced ER stress. 12/15-LO action involves upregulation of interleukin-12 (IL-12) expression. Tunicamycin significantly upregulated IL-12p40 expression in adipocytes, and IL-12 addition increased ER stress gene expression; conversely, LSF, an IL-12 signaling inhibitor, and an IL-12p40-neutralizing antibody attenuated tunicamycin-induced ER stress. Isolated adipocytes and liver from 12/15-LO-deficient mice fed a high-fat diet revealed a decrease in spliced XBP-1 expression compared with wild-type C57BL/6 mice on a high-fat diet. Furthermore, pancreatic islets from 12/15-LO-deficient mice showed reduced high-fat diet-induced ER stress genes compared with wild-type mice. These data suggest that 12/15-LO activity participates in ER stress in adipocytes, pancreatic islets, and liver. Therefore, reduction of 12/15-LO activity or expression could provide a new therapeutic target to reduce ER stress and downstream inflammation linked to obesity.

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Abstract 292: The Role of the ATF6 Branch of the ER Stress Response in the Endocrine Heart

Circulation Research ◽

10.1161/res.119.suppl_1.292 ◽

2016 ◽

Vol 119 (suppl_1) ◽

Author(s):

Erik A Blackwood ◽

Christopher C Glembotski

Keyword(s):

Stress Response ◽

Er Stress ◽

Knockout Mice ◽

Ex Vivo ◽

Proteolytic Cleavage ◽

Isolated Perfused Heart ◽

Wild Type ◽

Atrial Myocytes ◽

Perfused Heart ◽

Er Stress Response

Rationale: Atrial natriuretic peptide (ANP) is stored in the heart in large dense core granules of atrial myocytes as a biologically inactive precursor, pro-ANP. Hemodynamic stress and atrial stretch stimulate coordinate secretion and proteolytic cleavage of pro-ANP to its bioactive form, ANP, which promotes renal salt excretion and vasodilation, which, together contribute to decreasing blood pressure. While the ATF6 branch of the ER stress response has been studied in ventricular tissue mouse models of myocardial ischemia and pathological hypertrophy, roles for ATF6 and ER stress on the endocrine function of atrial myocytes have not been studied. Objective/Methods: To address this gap in our knowledge, we knocked down ATF6 in primary cultured neonatal rat atrial myocytes (NRAMs) using a chemical inhibitor of the proteolytic cleavage site enabling ATF6 activation and siRNA and measured ANP expression and secretion basally and in response to alpha- adrenergic agonist stimulation using phenylephrine. We also compared the ANP secretion from wild- type mice and ATF6 knockout mice in an ex vivo Langendorff model of the isolated perfused heart. Results: ATF6 knockdown in NRAMs significantly impaired basal and phenylephrine-stimulated ANP secretion. ATF6 knockout mice displayed lower levels of ANP in atrial tissue at baseline as well as after phenylephrine treatment. Similarly, in the ex vivo isolated perfused heart model, less ANP was detected in effluent of ATF6 knockout hearts compared to wild-type hearts. Conclusions: The ATF6 branch of the ER stress response is necessary for efficient co-secretional processing of pro-ANP to ANP and for agonist-stimulated ANP secretion from atrial myocytes. As ANP is secreted in a regulated manner in response to a stimulus and pro-ANP is synthesized and packaged through the classical secretory pathway, we posit that ATF6 is required for adequate expression, folding, trafficking, processing and secretion of biologically active ANP from the endocrine heart.

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Abstract 415: Cardioprotective Effects of Interleukin-15 in Immortalized Human Ventricular Cardiomyocytes

Circulation Research ◽

10.1161/res.117.suppl_1.415 ◽

2015 ◽

Vol 117 (suppl_1) ◽

Author(s):

Marin Jane McBride ◽

Kristina Durham ◽

Bernardo L Trigatti

Keyword(s):

Stress Response ◽

Er Stress ◽

Interleukin 2 ◽

Cell Types ◽

Human Cardiomyocytes ◽

Er Stress Response ◽

Distinct Cell ◽

Receptor Chain ◽

Interleukin 15 ◽

Receptor Beta

Interleukin-15 (IL-15) is a pleotropic cytokine that has a profound effect on the proliferation, survival and differentiation of many distinct cell types. The IL-15 receptor complex has 3 subunits: the unique receptor chain IL-15 receptor alpha (IL-15Rα), and two receptor chains shared with interleukin-2 (IL-2) and/or other cytokines, referred to as IL-2 receptor beta (IL-2Rβ) and IL-2 receptor gamma/gamma common chain (IL-2Rγ/γc), respectively. To our knowledge, this is the first study to examine the effects of IL-15 in immortalized human cardiomyocytes. Data collected by RT-PCR shows mRNA expression of IL-15Rα, IL-2Rβ and IL-2 Rγ/γc in these cells. Additionally, western blotting for IL-15Rα, IL-2Rβ and IL-2 Rγ/γc confirms the presence of all three IL-15 receptors. Early experiments examining the effect of IL-15 on cardiomyocyte cell survival show a statistically significant protective effect of IL-15 on the survival of cells exposed to tunicamycin, a pharamacological endoplasmic reticulum (ER) stress inducing agent. These findings suggest that IL-15 signaling may be an important cardioprotective pathway that is involved in the cardiac ER stress response. As ER stress is a major component of multiple different cardiac pathologies, such as myocardial infarction, heart failure and diabetes, uncovering the molecular mechanism by which IL-15 protects the heart will allow for deeper understanding of the cardiac ER stress response.

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