scholarly journals Cell-specific expression of X-linked inhibitor of apoptosis in the anterior pituitary of streptozotocin-induced diabetic rats

2007 ◽  
Vol 192 (1) ◽  
pp. 215-227 ◽  
Author(s):  
Ana I Arroba ◽  
Alfonso M Lechuga-Sancho ◽  
Laura M Frago ◽  
Jesús Argente ◽  
Julie A Chowen
Keyword(s):  
Cell Death ◽  
Anterior Pituitary ◽  
Cell Types ◽  
Diabetic Rats ◽  
Inhibitor Of Apoptosis ◽  
Specific Cell ◽  
Cell Protection ◽  
Specific Expression ◽  
Cell Death Pathway ◽  
Apoptosis Protein

Cell death is increased in the anterior pituitary of poorly controlled diabetic rats, but anti-apoptotic mechanisms are also activated. We hypothesized that specific cell types are selectively protected against diabetes-induced cell death. To determine when anti-apoptotic mechanisms are activated, streptozotocin-induced diabetic rats were killed after 1, 4, 6 and 8 weeks of evolution. Anterior pituitaries were processed for western blot analysis to determine changes in the intrinsic cell death pathway and upstream kinases involved in cell protection mechanisms. An increase in cell death was detected by ELISA at 4 weeks of diabetes. TUNEL labelling demonstrated that this corresponded to death of primarily lactotrophs, a few somatotrophs, and no thyrotrophs, corticotrophs or gonadotrophs. Levels of phosphorylated (p) Akt were increased at 1 week of diabetes, while pERK1/2 levels increased at 4 weeks and pJNK at 6 weeks. Activation of caspase 3 decreased and anti-apoptotic members of the Bcl-2 protein family increased as early as 1 week after diabetes onset. These changes were coincident with increased IGF-I receptor levels. Levels of X-linked inhibitor of apoptosis protein (XIAP) increased significantly after 6 weeks of diabetes, as did activation of nuclear factor (NF)κB. Double immunohistochemistry indicated that XIAP was expressed in less than 1% of lactotrophs and gonadotrophs, approximately 50% of somatotrophs and more than 90% of corticotrophs and thyrotrophs. These results suggest that some cell survival mechanisms are rapidly activated in the anterior pituitary, even before increased cell death can be detected, while others are more delayed. Furthermore, both pituitary cell death and expression of protective mechanisms such as XIAP are cell-type specific.

scholarly journals Increased apoptosis of lactotrophs in streptozotocin-induced diabetic rats is followed by increased proliferation

2006 ◽  
Vol 191 (1) ◽  
pp. 55-63 ◽  
Author(s):  
Ana I Arroba ◽  
Alfonso M Lechuga-Sancho ◽  
Laura M Frago ◽  
Jesús Argente ◽  
Julie A Chowen
Keyword(s):  
Cell Proliferation ◽  
Cell Death ◽  
Anterior Pituitary ◽  
Diabetic Rats ◽  
Brdu Incorporation ◽  
Caspase 8 ◽  
Cell Type ◽  
Diabetes Onset ◽  
Cell Death Pathway ◽  
Tnf Α

Poorly controlled diabetes mellitus can result in decreased prolactin production and thus problems with lactation, reproduction, and other physiological processes. This may be due to a loss of lactotrophs, as we have previously shown that long-term (8 weeks) poorly controlled streptozotocin-induced diabetes results in increased death of lactotrophs and that this most likely occurs through the activation of caspase-8 and the extrinsic cell death cascade. However, cell proliferation is also increased in the anterior pituitary at this time, although the cell type undergoing this proliferation and whether it is a response to the increased cell death remains unknown. In order to determine the time-course of increased cell death and proliferation in the anterior pituitary and if this is related to changes in tumor necrosis factor (TNF)-α, a cytokine involved in the activation of the extrinsic cell death pathway, rats were killed at 1, 4, 6, and 8 weeks after the induction of diabetes. Cell death was significantly increased after 4 weeks, as was caspase-8 activation, although circulating levels of TNF-α were increased as early as 1 week. Pituitary levels of TNF-α did not change significantly until 8 weeks after diabetes onset. Similarly, Western-blot analysis of proliferating cell nuclear antigen showed that anterior pituitary cell proliferation increased significantly 8 weeks after diabetes onset, with the majority of proliferating cells, as detected by BrdU incorporation, corresponding to lactotrophs. These results suggest that the increased death of lactotrophs in poorly controlled diabetic rats is followed by increased proliferation of this cell type, even when no treatment is given.

scholarly journals Activation of Caspase 8 in the Pituitaries of Streptozotocin-Induced Diabetic Rats: Implication in Increased Apoptosis of Lactotrophs

Endocrinology ◽  
2005 ◽  
Vol 146 (10) ◽  
pp. 4417-4424 ◽  
Author(s):  
Ana I. Arroba ◽  
Laura M. Frago ◽  
Jesús Argente ◽  
Julie A. Chowen
Keyword(s):  
Cell Death ◽  
Nuclear Factor Κb ◽  
Diabetic Rats ◽  
Male Rats ◽  
Diabetic Rat ◽  
Caspase 8 ◽  
Control Male ◽  
Cell Death Pathway ◽  
Xiap Expression ◽  
Apoptosis Protein

Lactotroph cell death is increased in streptozotocin-induced diabetic rats. To determine the mechanism involved, cell death proteins were accessed in pituitaries of diabetic (streptozotocin at 65 mg/kg, 2 months evolution) and control male rats by Western blot analysis and double immunohistochemistry. The intact and cleaved forms of caspase 9 were increased in diabetic rat pituitaries compared with controls. Although the proforms of caspases 3, 6, and 7 were increased in diabetic rat pituitaries, their activated forms were either unchanged or decreased. Activation of these effector caspases may be blocked by the increased expression of X-chromosome-linked inhibitor of apoptosis protein (XIAP) in diabetic rat pituitaries. However, in diabetic rats, XIAP expression in lactotrophs was decreased, suggesting that this cell type is not protected. Caspase 8, p53, and nuclear factor κB were more highly activated in diabetic rat pituitaries, with caspase 8 colocalization in lactotrophs being increased. These results suggest that, in the pituitaries of diabetic rats, the cascades of normal cell turnover are partially inhibited, possibly via XIAP, and this may be cell specific. Furthermore, activation of the extrinsic cell-death pathway, including activation of caspase 8, may underlie the diabetes-associated increase in lactotroph death.

scholarly journals Pseudomonas aeruginosaDelays Kupffer Cell Death via Stabilization of the X-Chromosome-Linked Inhibitor of Apoptosis Protein

2007 ◽  
Vol 179 (1) ◽  
pp. 505-513 ◽  
Author(s):  
Alix Ashare ◽  
Martha M. Monick ◽  
Amanda B. Nymon ◽  
John M. Morrison ◽  
Matthew Noble ◽  
...  
Keyword(s):  
Cell Death ◽  
X Chromosome ◽  
Kupffer Cell ◽  
Inhibitor Of Apoptosis ◽  
Inhibitor Of Apoptosis Protein ◽  
Apoptosis Protein

scholarly journals The Immuno-Modulatory Effects of Inhibitor of Apoptosis Protein Antagonists in Cancer Immunotherapy

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 207 ◽  
Author(s):  
Jessica Michie ◽  
Conor J. Kearney ◽  
Edwin D. Hawkins ◽  
John Silke ◽  
Jane Oliaro
Keyword(s):  
Cell Death ◽  
Cancer Cells ◽  
Tumour Progression ◽  
Mitochondrial Protein ◽  
Immune Checkpoint Blockade ◽  
Oncolytic Viruses ◽  
Inhibitor Of Apoptosis ◽  
T Cell Therapy ◽  
Apoptosis Protein ◽  
Smac Mimetics

One of the hallmarks of cancer cells is their ability to evade cell death via apoptosis. The inhibitor of apoptosis proteins (IAPs) are a family of proteins that act to promote cell survival. For this reason, upregulation of IAPs is associated with a number of cancer types as a mechanism of resistance to cell death and chemotherapy. As such, IAPs are considered a promising therapeutic target for cancer treatment, based on the role of IAPs in resistance to apoptosis, tumour progression and poor patient prognosis. The mitochondrial protein smac (second mitochondrial activator of caspases), is an endogenous inhibitor of IAPs, and several small molecule mimetics of smac (smac-mimetics) have been developed in order to antagonise IAPs in cancer cells and restore sensitivity to apoptotic stimuli. However, recent studies have revealed that smac-mimetics have broader effects than was first attributed. It is now understood that they are key regulators of innate immune signalling and have wide reaching immuno-modulatory properties. As such, they are ideal candidates for immunotherapy combinations. Pre-clinically, successful combination therapies incorporating smac-mimetics and oncolytic viruses, as with chimeric antigen receptor (CAR) T cell therapy, have been reported, and clinical trials incorporating smac-mimetics and immune checkpoint blockade are ongoing. Here, the potential of IAP antagonism to enhance immunotherapy strategies for the treatment of cancer will be discussed.

scholarly journals Diablo Promotes Apoptosis by Removing Miha/Xiap from Processed Caspase 9

2001 ◽  
Vol 152 (3) ◽  
pp. 483-490 ◽  
Author(s):  
Paul G. Ekert ◽  
John Silke ◽  
Christine J. Hawkins ◽  
Anne M. Verhagen ◽  
David L. Vaux
Keyword(s):  
Cell Death ◽  
Cytochrome C ◽  
Caspase 3 ◽  
Direct Interaction ◽  
Inhibitor Of Apoptosis ◽  
Caspase 9 ◽  
Inhibitor Of Apoptosis Protein ◽  
Grim Reaper ◽  
Apoptosis Protein ◽  
Mammalian Protein

MIHA is an inhibitor of apoptosis protein (IAP) that can inhibit cell death by direct interaction with caspases, the effector proteases of apoptosis. DIABLO is a mammalian protein that can bind to IAPs and antagonize their antiapoptotic effect, a function analogous to that of the proapoptotic Drosophila molecules, Grim, Reaper, and HID. Here, we show that after UV radiation, MIHA prevented apoptosis by inhibiting caspase 9 and caspase 3 activation. Unlike Bcl-2, MIHA functioned after release of cytochrome c and DIABLO from the mitochondria and was able to bind to both processed caspase 9 and processed caspase 3 to prevent feedback activation of their zymogen forms. Once released into the cytosol, DIABLO bound to MIHA and disrupted its association with processed caspase 9, thereby allowing caspase 9 to activate caspase 3, resulting in apoptosis.

scholarly journals Distinct cell death pathways triggered by the adenovirus early region 4 ORF 4 protein

2002 ◽  
Vol 158 (3) ◽  
pp. 519-528 ◽  
Author(s):  
Amélie Robert ◽  
Marie-Joëlle Miron ◽  
Claudia Champagne ◽  
Marie-Claude Gingras ◽  
Philip E. Branton ◽  
...  
Keyword(s):  
Cell Death ◽  
Critical Role ◽  
Adenovirus Type ◽  
Cell Types ◽  
Specific Cell ◽  
Nuclear Targeting ◽  
Early Region ◽  
Delayed Cell Death ◽  
Distinct Cell ◽  
Early Region 4

In transformed cells, induction of apoptosis by adenovirus type 2 (Ad2) early region 4 ORF 4 (E4orf4) correlates with accumulation of E4orf4 in the cell membrane–cytoskeleton fraction. However, E4orf4 is largely expressed in nuclear regions before the onset of apoptosis. To determine the relative contribution of nuclear E4orf4 versus membrane-associated E4orf4 to cell death signaling, we engineered green fluorescent fusion proteins to target E4orf4 to specific cell compartments. The targeting of Ad2 E4orf4 to cell membranes through a CAAX-box or a myristylation consensus signal sufficed to mimic the fast Src-dependent apoptotic program induced by wild-type E4orf4. In marked contrast, the nuclear targeting of E4orf4 abolished the early induction of extranuclear apoptosis. However, nuclear E4orf4 still induced a delayed cell death response independent of Src-like activity and of E4orf4 tyrosine phosphorylation. The zVAD.fmk-inhibitable caspases were dispensable for execution of both cell death programs. Nevertheless, both pathways led to caspase activation in some cell types through the mitochondrial pathway. Finally, our data support a critical role for calpains upstream in the death effector pathway triggered by the Src-mediated cytoplasmic death signal. We conclude that Ad2 E4orf4 induces two distinct cell death responses, whose relative contributions to cell killing may be determined by the genetic background.

Missing mitochondrial Mpv17 gene function induces tissue-specific cell-death pathway in the degenerating inner ear

2012 ◽  
Vol 347 (2) ◽  
pp. 343-356 ◽  
Author(s):  
Angela-Maria Meyer zum Gottesberge ◽  
Thomas Massing ◽  
Stefan Hansen
Keyword(s):  
Cell Death ◽  
Inner Ear ◽  
Gene Function ◽  
Specific Cell ◽  
Tissue Specific ◽  
Cell Death Pathway

scholarly journals Identification of a Cell Death Pathway in Candida albicans during the Response to Pheromone

2010 ◽  
Vol 9 (11) ◽  
pp. 1690-1701 ◽  
Author(s):  
Kevin Alby ◽  
Dana Schaefer ◽  
Racquel Kim Sherwood ◽  
Stephen K. Jones ◽  
Richard J. Bennett
Keyword(s):  
Cell Death ◽  
Candida Albicans ◽  
Laboratory Strain ◽  
Opportunistic Pathogen ◽  
Cell Types ◽  
Yeast Cells ◽  
Phenotypic Switching ◽  
Morphological Response ◽  
Content Type ◽  
Cell Death Pathway

ABSTRACT Mating in hemiascomycete yeasts involves the secretion of pheromones that induce sexual differentiation in cells of the opposite mating type. Studies in Saccharomyces cerevisiae have revealed that a subpopulation of cells experiences cell death during exposure to pheromone. In this work, we tested whether the phenomenon of pheromone-induced death (PID) also occurs in the opportunistic pathogen Candida albicans. Mating in C. albicans is uniquely regulated by white-opaque phenotypic switching; both cell types respond to pheromone, but only opaque cells undergo the morphological transition and cell conjugation. We show that approximately 20% of opaque cells, but not white cells, of laboratory strain SC5314 experience pheromone-induced death. Furthermore, analysis of mutant strains revealed that PID was significantly reduced in strains lacking Fig1 or Fus1 transmembrane proteins that are induced during the mating process and, we now show, are necessary for efficient mating in C. albicans. The level of PID was also Ca2+ dependent, as chelation of Ca2+ ions increased cell death to almost 50% of the population. However, in contrast to S. cerevisiae PID, pheromone-induced killing of C. albicans cells was largely independent of signaling via the Ca2+-dependent protein phosphatase calcineurin, even when combined with the loss of Cmk1 and Cmk2 proteins. Finally, we demonstrate that levels of PID vary widely between clinical isolates of C. albicans, with some strains experiencing close to 70% cell death. We discuss these findings in light of the role of prodeath and prosurvival pathways operating in yeast cells undergoing the morphological response to pheromone.

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