No abstract available.
eIF-2 Kinase* ; HIV-1* ; Phosphorylation

Detection of pathogen by pattern recognition receptors leads to activation of inflammasome which plays a crucial role in immune system. The inflammasome regulates the release of cytokines, such as interleukin (IL)-1beta, IL-18 and high-mobility group box 1 (HMGB1). Double-stranded RNA-dependent protein kinase (PKR) is a critical component of an inflammatory complex. Recently, the critical role of PKR was reported in regulation of multiple inflammasomes.
Cytokines ; eIF-2 Kinase ; Immune System ; Inflammasomes ; Interleukin-18 ; Interleukins ; Receptors, Pattern Recognition

The patient was a female infant aged 1 month and 29 days. She was admitted to the hospital due to convulsions for 6 days and increased blood glucose level for 5 days. She had unstable blood glucose levels. The level of glycosylated hemoglobin was too high to measure. Urine glucose was positive (+ - ++++). The levels of fasting C-peptide and insulin were 0.19 ng/mL and 11.68 μIU/mL respectively. High-throughput sequencing of the genetic endocrine disease gene Panel (412 detected genes, including 49 known diabetes-related genes) showed that the EIF2AK3 gene in the infant had two novel compound heterozygous mutations, c.2731_2732delAG and c.2980G>A, both of which were located in the kinase domain. The infant was diagnosed with Wolcott-Rallison syndrome (WRS). As a rare autosomal recessive disease, WRS is characterized by neonatal diabetes, multiple epiphyseal dysphasia and liver disease. Neonatal diabetes is a prerequisite for the diagnosis of WRS. The EIF2AK3 gene is the pathogenic gene of WRS.
Diabetes Mellitus, Type 1 ; Epiphyses ; abnormalities ; Female ; Humans ; Infant ; Mutation ; Osteochondrodysplasias ; eIF-2 Kinase

High mobility group box 1 (HMGB1) is an evolutionarily conserved non-histone chromatin-binding protein. During infection or injury, activated immune cells and damaged cells release HMGB1 into the extracellular space, where HMGB1 functions as a proinflammatory mediator and contributes importantly to the pathogenesis of inflammatory diseases. Recent studies reveal that inflammasomes, intracellular protein complexes, critically regulate HMGB1 release from activated immune cells in response to a variety of exogenous and endogenous danger signals. Double stranded RNA dependent kinase (PKR), an intracellular danger-sensing molecule, physically interacts with inflammasome components and is important for inflammasome activation and HMGB1 release. Together, these studies not only unravel novel mechanisms of HMGB1 release during inflammation, but also provide potential therapeutic targets to treat HMGB1-related inflammatory diseases.
HMGB1 Protein ; chemistry ; metabolism ; Humans ; Inflammasomes ; metabolism ; Macrophages ; immunology ; metabolism ; eIF-2 Kinase ; metabolism

To explore the protective effect and mechanism of ethyl acetate extract from Bidens bipinnata on hepatocyte damage induced by endoplasmic reticulum stress. Tunicamycin was used to establish the damage model in L02 cells. Methyl thiazolyl tetrazolium(MTT) colorimetric assay was used to investigate the survival rate of ethyl acetate extract from B. bipinnata in L02 cells injury induced by endoplasmic reticulum stress; the protein expressions of endoplasmic reticulum stress-related molecule glucose regulated protein 78(GRP78), PKR-like ER kinase(PERK), eukaryotic initiation factor-2(eIF2α), activating transcription factor 4(ATF4), C/EBP homologous protein(CHOP), B-cell CLL/lymphoma 2(Bcl-2), Bal-2 associated X apoptosis regulator(Bax) were examined by Wes-tern blot. The expressions of the above proteins were also detected after endoplasmic reticulum stress inhibitor(4-phenyl butyric acid) and CHOP shRNA-mediated knockdowns were added. The expressions of GRP78, PERK, CHOP in L02 cells were observed by immunofluorescence method. The results showed that ethyl acetate extract from B. bipinnata could significantly increase the survival rate of L02 cell injury caused by endoplasmic reticulum stress in a dose and time-dependent manner(P<0.05 or P<0.01). The expression levels of GRP78, PERK, eIF2α, ATF4, CHOP and Bax in the drug treatment groups were significantly down-regulated(P<0.05 or P<0.01), while Bcl-2 was significantly up-regulated(P<0.01). After endoplasmic reticulum stress inhibitor and CHOP shRNA-mediated knockdowns were added, the expression levels of GRP78, PERK, eIF2α, ATF4, CHOP, Bax in the drug treatment groups were significantly down-regulated(P<0.01), whereas Bcl-2 was significantly up-regulated(P<0.01). Immunofluorescence results showed that the expressions of GRP78, PERK, CHOP were consistent with the Western blot method. In conclusion, ethyl acetate extract from B. bipinnata has a significant protective effect on the damage of L02 cells caused by endoplasmic reticulum stress. The mechanism may be related to the inhibition of endoplasmic reticulum stress and the down-regulation of apoptosis in cells through the PERK/eIF2α/ATF4/CHOP signaling pathway.
Acetates ; Apoptosis ; Bidens ; Endoplasmic Reticulum Stress ; Hepatocytes ; Transcription Factor CHOP/genetics* ; eIF-2 Kinase/genetics*

In eukaryotic cells, the endoplasmic reticulum (ER) is the key quality control organelle for cellular protein synthesis and processing. It also serves as an important site for Ca
Adipose Tissue ; Diabetes Mellitus, Type 2 ; Endoplasmic Reticulum Stress ; Endoribonucleases ; Humans ; Protein-Serine-Threonine Kinases ; eIF-2 Kinase

OBJECTIVEWolcott-Rallison syndrome (WRS) is a rare autosomal recessive disorder characterized by the association of permanent neonatal or early-infancy insulin-dependent diabetes, multiple epiphyseal dysplasia and growth retardation, and other variable multisystem clinical manifestations. Here we describe a Chinese boy affected by WRS. Genetic testing of his EIF2AK3 gene was performed in order to elucidate molecular variations and subsequently to provide credible genetic counseling for prenatal diagnosis in his family.

METHODBased on analysis of a nine-year-old boy's clinical symptoms associated with biochemical examination and imaging, the diagnosis of WRS was therefore made. Genomic DNAs were extracted from peripheral blood leukocytes from the boy and his parents with their informed consent for genetic studies. All EIF2AK3 exons and intron-exon boundaries were amplified by Touch-down polymerase chain reaction (Touch-down PCR) and sequenced.

RESULTDirect sequencing of PCR products revealed the presence of a heterozygous T insertion (c.1408_1409insT) in exon 8 of the EIF2AK3 gene leading to frameshifting and termination, and another heterozygous T to A exchange (c.1596T > A) in exon 9 of the EIF2AK3 gene resulting in nonsense C532X mutation.

CONCLUSIONCombining mutation screening of EIF2AK3 gene with clinical manifestations and effective examination may provide a reliable diagnostic method for patients. In this research, two novel mutations identified in the Chinese boy locate in the catalytic domain of the EIF2AK3 gene, disrupting the ability of autophosphorylation, leading to the truncated proteins that are unable to phosphorylate the natural substrate, which are responsible for the phenotype of Wolcott-Rallison syndrome.

Child ; Diabetes Mellitus, Type 1 ; genetics ; Epiphyses ; abnormalities ; Humans ; Male ; Mutation ; Osteochondrodysplasias ; genetics ; eIF-2 Kinase ; genetics

OBJECTIVETo investigate the role of PERK/eIF2alpha signaling pathway in hepatocyte apoptosis of alcoholic liver injury rats.

METHODSRat models with ethanol-induced liver injury were successfully developed by gastric gavage with ethanol-corn oil mixtures for 12 weeks. At different time points (4, 6, 10, 12 week), liver pathology was dynamically observed. The hepatocyte apoptosis was quantitatively analyzed by Annexin V-FITC/PI double-labeled flow cytometry, the serum total homocysteine (tHCY) level was detected by ELISA and the expressions of eIF2a, p-eIF2a, GRP78/Bip, GRP94, caspase-3 and caspase-12 in liver were examined using Real-time PCR and Western blot.

RESULTSTypical acute liver injury and chronic liver injury were observed at week 4 and week 12 respectively. The hepatocyte apoptosis rates in 6-week model rats significantly increased compared with normal rats (P value less than 0.05), and the degree of hepatocyte apoptosis continued to increase with the modeling time, and the percentages of early and total apoptosis reached 26% and 29% at week 12. From week 6 to week 12, the serum tHCY levels in model rats were obviously higher than in normal rats (P value less than 0.01). Since week 4, eIF2a protein phosphorylation in model rat livers remarkably elevated compared with that in normal rat livers (P value less than 0.01), and at week 12 the peIF2a protein expression in model rat livers increased by 2.81-fold. Since week 4 the expressions of GRP78/Bip, GRP94, caspase-12 and caspase-3 mRNA and protein in model rat livers showed a significant increase as compared to normal rat livers, and at week 12, these gene and protein levels increased 4.70, 12.95, 3.83, 4.05 fold and 3.93, 6.93, 9.88, 3.31 fold, respectively (P value less than 0.01).

CONCLUSIONActivation of PERK/eIF2a signaling pathway contributes to the occurrence and development of hepatocyte apoptosis in alcoholic liver injury rats and it might be as a potential target for therapeutic applications in alcoholic liver diseases.

Animals ; Apoptosis ; Eukaryotic Initiation Factor-2 ; metabolism ; Hepatocytes ; cytology ; pathology ; Liver Diseases, Alcoholic ; metabolism ; pathology ; Male ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; eIF-2 Kinase ; metabolism

OBJECTIVEPERK/eIF2α/CHOP is a major signaling pathway mediating endoplasmic reticulum (ER) stress related with atherosclerosis. Oxidized LDL (ox-LDL) also induces endothelial apoptosis and plays a vital role in the initiation and progression of atherosclerosis. The present study was conducted to explore the regulatory effect of ox-LDL on PERK/eIF2α/CHOP signaling pathway in vascular endothelial cells.

METHODSThe effects of ox-LDL on PERK and p-eIF2α protein expression of primary human umbilical vein endothelial cells (HUVECs) were investigated by Western blot analysis. PERK gene silencing and selective eIF2α phosphatase inhibitor, salubrinal were used to inhibit the process of ox-LDL induced endothelial cell apoptosis, caspase-3 activity, and CHOP mRNA level.

RESULTSOx-LDL treatment significantly increased the expression of PERK, PERK-mediated inactivation of eIF2α phosphorylation, and the expression of CHOP, as well as the caspase-3 activity and apoptosis. The effects of ox-LDL were markedly decreased by knocking down PERK with stable transduction of lentiviral shRNA or by selective eIF2α phosphatase inhibitor, salubrinal.

CONCLUSIONThis study provides the first evidence that ox-LDL induces apoptosis in vascular endothelial cells mediated largely via the PERK/eIF2α/CHOP ER-stress pathway. It adds new insights into the molecular mechanisms underlying the pathogenesis and progression of atherosclerosis.

Apoptosis ; Endoplasmic Reticulum Stress ; Eukaryotic Initiation Factor-2 ; genetics ; metabolism ; Human Umbilical Vein Endothelial Cells ; metabolism ; Humans ; Lipoproteins, LDL ; genetics ; metabolism ; Signal Transduction ; Transcription Factor CHOP ; genetics ; metabolism ; eIF-2 Kinase ; genetics ; metabolism

Intrinsic cellular defenses are non-specific antiviral activities by recognizing pathogen-associated molecular patterns (PAMPs). Toll-like receptors (TLRs), one of the pathogen recognize receptor (PRR), sense various microbial ligands. Especially, TLR2, TLR3, TLR4, TLR7, TLR8 and TLR9 recognize viral ligands such as glycoprotein, single- or double-stranded RNA and CpG nucleotides. The binding of viral ligands to TLRs transmits its signal to Toll/interleukin-1 receptor (TIR) to activate transcription factors via signal transduction pathway. Through activation of transcription factors, such as interferon regulatory factor-3, 5, and 7 (IRF-3, 5, 7) or nuclear factor-kappaB (NF-kappaB), type I interferons are induced, and antiviral proteins such as myxovirus-resistance protein (Mx) GTPase, RNA-dependent Protein Kinase (PKR), ribonuclease L (RNase L), Oligo-adenylate Synthetase (OAS) and Interferon Stimulated Gene (ISG) are further expressed. These antiviral proteins play an important role of antiviral resistancy against several viral pathogens in infected cells and further activate innate immune responses.
Animals ; GTP-Binding Proteins/metabolism ; Humans ; Interferon Regulatory Factors/metabolism ; Interferon Type I/*metabolism/physiology ; Models, Biological ; NF-kappa B/metabolism ; Toll-Like Receptors/metabolism ; Virus Diseases/*immunology/*metabolism/virology ; eIF-2 Kinase/metabolism