scholarly journals Eukaryotic translation initiation factor 5A inhibition alters physiopathology and immune responses in a “humanized” transgenic mouse model of type 1 diabetes

2014 ◽  
Vol 306 (7) ◽  
pp. E791-E798 ◽  
Author(s):  
Shahnawaz Imam ◽  
Raghavendra G. Mirmira ◽  
Juan C. Jaume
Keyword(s):  
T Cells ◽  
Type 1 Diabetes ◽  
Translation Initiation ◽  
Immune Modulation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
T Regulatory Cell ◽  
Deoxyhypusine Synthase ◽  
Diabetes Outcome

Therapeutic options for treatment of type 1 diabetes (T1D) are still missing. New avenues for immune modulation need to be developed. Here we attempted at altering the diabetes outcome of our humanized model of T1D by inhibiting translation-initiation factor eIF5A hypusination in vivo. Double-transgenic (DQ8-GAD65) mice were immunized with adenoviral vectors carrying GAD65 for diabetes induction. Animals were subsequently treated with deoxyhypusine synthase (DHS) inhibitor GC7 and monitored for diabetes development over time. On one hand, helper CD4+ T cells were clearly affected by the downregulation of the eIF5A not just at the pancreas level but overall. On the other hand, the T regulatory cell component of CD4 responded with activation and proliferation significantly higher than in the non-GC7-treated controls. Female mice seemed to be more susceptible to these effects. All together, our results show for the first time that downregulation of eIF5A through inhibition of DHS altered the physiopathology and observed immune outcome of diabetes in an animal model that closely resembles human T1D. Although the development of diabetes could not be abrogated by DHS inhibition, the immunomodulatory capacity of this approach may supplement other interventions directed at increasing regulation of autoreactive T cells in T1D.

scholarly journals Human deoxyhypusine synthase: interrelationship between binding of NAD and substrates

2000 ◽  
Vol 352 (3) ◽  
pp. 851-857 ◽  
Author(s):  
Chang Hoon LEE ◽  
Myung Hee PARK
Keyword(s):  
Reaction Mechanism ◽  
Conformational Change ◽  
Translation Initiation ◽  
Binding Sites ◽  
Cellular Protein ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Deoxyhypusine Synthase ◽  
Eukaryotic Translation ◽  
Eukaryotic Translation Initiation

Deoxyhypusine synthase catalyses the NAD-dependent transfer of the butylamine moiety from the polyamine, spermidine, to a specific lysine residue of a single cellular protein, eukaryotic translation-initiation factor 5A (eIF5A) precursor. The native enzyme exists as a tetramer of four identical subunits and contains four binding sites for NAD. The binding of spermidine and NAD was studied by a filtration assay. [3H]Spermidine binding to the enzyme was not detectable alone or in the presence of the eIF5A precursor, but was detected only in the presence of NAD or NADH, suggesting that a NAD/NADH-induced conformational change is required for the binding of spermidine. A strong NAD-dependent binding was also observed with a spermidine analogue, N1-guanyl-1,7-diamino[3H]heptane (GC7), but not with [14C]putrescine or [14C]spermine. Although [3H]NAD binding to the enzyme occurred in the absence of spermidine, its affinity for the enzyme was markedly enhanced by spermidine, GC7 and also by the eIF5A precursor. The maximum binding for NAD and spermidine was estimated to be ≈ 4 molecules each/enzyme tetramer. The dependence of spermidine binding on NAD and the modulation of binding of NAD by spermidine and the eIF5A precursor suggest intricate relationships between the binding of cofactor and the substrates, and provide new insights into the reaction mechanism.

scholarly journals Independent roles of eIF5A and polyamines in cell proliferation

2005 ◽  
Vol 385 (3) ◽  
pp. 779-785 ◽  
Author(s):  
Kazuhiro NISHIMURA ◽  
Kaori MUROZUMI ◽  
Akira SHIRAHATA ◽  
Myung Hee PARK ◽  
Keiko KASHIWAGI ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Growth ◽  
Translation Initiation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Deoxyhypusine Synthase ◽  
Eukaryotic Translation ◽  
Spermine Synthase ◽  
Polyamine Content ◽  
Eukaryotic Translation Initiation

To examine the roles of active hypusinated eIF5A (eukaryotic translation initiation factor 5A) and polyamines in cell proliferation, mouse mammary carcinoma FM3A cells were treated with an inhibitor of deoxyhypusine synthase, GC7 (N1-guanyl-1, 7-diaminoheptane), or with an inhibitor of ornithine decarboxylase, DFMO (α-difluoromethylornithine), or with DFMO plus an inhibitor of spermine synthase, APCHA [N1-(3-aminopropyl)-cyclohexylamine]. Treatment with GC7 decreased the level of active eIF5A on day 1 without affecting cellular polyamine content, and inhibition of cell growth occurred from day 2. This delay reflects the fact that eIF5A was present in excess and was very stable in these cells. Treatment with DFMO or with DFMO plus APCHA inhibited cell growth on day 1. DFMO considerably decreased the levels of putrescine and spermidine, and the formation of active eIF5A began to decrease when the level of spermidine fell below 8 nmol/mg of protein after 12 h of incubation with DFMO. The combination of DFMO and APCHA markedly decreased the levels of putrescine and spermine and significantly decreased the level of spermidine, but did not affect the level of active eIF5A until day 3 when spermidine level decreased to 7 nmol/mg of protein. The results show that a decrease in either active eIF5A or polyamines inhibits cell growth, indicating that eIF5A and polyamines are independently involved in cell growth.

scholarly journals Immune interventions to preserve β cell function in type 1 diabetes

2016 ◽  
Vol 64 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Mario R Ehlers
Keyword(s):  
T Cells ◽  
Type 1 Diabetes ◽  
Regulatory T Cells ◽  
Immune Modulation ◽  
Cell Function ◽  
Cell Mass ◽  
Β Cells ◽  
Β Cell

Type 1 diabetes (T1D) is a chronic autoimmune disease that leads to destruction of pancreatic β cells, lifelong dependence on insulin, and increased morbidity and mortality from diabetes-related complications. Preservation of residual β cells at diagnosis is a major goal because higher levels of endogenous insulin secretion are associated with better short- and long-term outcomes. For the past 3 decades, a variety of immune interventions have been evaluated in the setting of new-onset T1D, including nonspecific immunosuppression, pathway-specific immune modulation, antigen-specific therapies, and cellular therapies. To date, no single intervention has produced durable remission off therapy in most treated patients, but the field has gained valuable insights into disease mechanisms and potential immunologic correlates of success. In particular, T-cell–directed therapies, including therapies that lead to partial depletion or modulation of effector T cells and preservation or augmentation of regulatory T cells, have shown the most success and will likely form the backbone of future approaches. The next phase will see evaluation of rational combinations, comprising one or more of the following: an effector T-depleting or -modulating drug, a cytokine-based tolerogenic (regulatory T-cells–promoting) agent, and an antigen-specific component. The long term goal is to reestablish immunologic tolerance to β cells, thereby preserving residual β cells early after diagnosis or enabling restoration of β-cell mass from autologous stem cells or induced neogenesis in patients with established T1D.

scholarly journals Robust T cell activation requires an eIF3-driven burst in T cell receptor translation

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Dasmanthie DeSilva ◽  
Lucas Ferguson ◽  
Grant H Chin ◽  
Benjamin E Smith ◽  
Ryan A Apathy ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Translation Initiation ◽  
Cell Activation ◽  
Cell Receptor ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Translation Control

Activation of T cells requires a rapid surge in cellular protein synthesis. However, the role of translation initiation in the early induction of specific genes remains unclear. Here we show human translation initiation factor eIF3 interacts with select immune system related mRNAs including those encoding the T cell receptor (TCR) subunits TCRA and TCRB. Binding of eIF3 to the TCRA and TCRB mRNA 3'-untranslated regions (3'-UTRs) depends on CD28 coreceptor signaling and regulates a burst in TCR translation required for robust T cell activation. Use of the TCRA or TCRB 3'-UTRs to control expression of an anti-CD19 chimeric antigen receptor (CAR) improves the ability of CAR-T cells to kill tumor cells in vitro. These results identify a new mechanism of eIF3-mediated translation control that can aid T cell engineering for immunotherapy applications.

scholarly journals Robust T cell activation requires an eIF3-driven burst in T cell receptor translation

2021 ◽  
Author(s):  
Dasmanthie DeSilva ◽  
Lucas Ferguson ◽  
Grant Chin ◽  
Benjamin Smith ◽  
Ryan Apathy ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Translation Initiation ◽  
Cell Activation ◽  
Cell Receptor ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Translation Control

Activation of T cells requires a rapid surge in cellular protein synthesis. However, the role of translation initiation in the early induction of specific genes remains unclear. Here we show human translation initiation factor eIF3 interacts with select immune system related mRNAs including those encoding the T cell receptor (TCR) subunits TCRA and TCRB. Binding of eIF3 to the TCRA and TCRB mRNA 3’-untranslated regions (3’-UTRs) depends on CD28 coreceptor signaling and regulates a burst in TCR translation required for robust T cell activation. Use of the TCRA or TCRB 3’-UTRs to control expression of an anti-CD19 chimeric antigen receptor (CAR) improves the ability of CAR-T cells to kill tumor cells in vitro. These results identify a new mechanism of eIF3-mediated translation control that can aid T cell engineering for immunotherapy applications.

scholarly journals Metabolic and immune effects of immunotherapy with proinsulin peptide in human new-onset type 1 diabetes

2017 ◽  
Vol 9 (402) ◽  
pp. eaaf7779 ◽  
Author(s):  
Mohammad Alhadj Ali ◽  
Yuk-Fun Liu ◽  
Sefina Arif ◽  
Danijela Tatovic ◽  
Hina Shariff ◽  
...  
Keyword(s):  
T Cells ◽  
Type 1 Diabetes ◽  
Immune Modulation ◽  
Cell Function ◽  
Human Leukocyte ◽  
Foxp3 Expression ◽  
Interleukin 10 ◽  
Β Cell ◽  
C Peptide

Immunotherapy using short immunogenic peptides of disease-related autoantigens restores immune tolerance in preclinical disease models. We studied safety and mechanistic effects of injecting human leukocyte antigen–DR4(DRB1*0401)–restricted immunodominant proinsulin peptide intradermally every 2 or 4 weeks for 6 months in newly diagnosed type 1 diabetes patients. Treatment was well tolerated with no systemic or local hypersensitivity. Placebo subjects showed a significant decline in stimulated C-peptide (measuring insulin reserve) at 3, 6, 9, and 12 months versus baseline, whereas no significant change was seen in the 4-weekly peptide group at these time points or the 2-weekly group at 3, 6, and 9 months. The placebo group’s daily insulin use increased by 50% over 12 months but remained unchanged in the intervention groups. C-peptide retention in treated subjects was associated with proinsulin-stimulated interleukin-10 production, increased FoxP3 expression by regulatory T cells, low baseline levels of activated β cell–specific CD8 T cells, and favorable β cell stress markers (proinsulin/C-peptide ratio). Thus, proinsulin peptide immunotherapy is safe, does not accelerate decline in β cell function, and is associated with antigen-specific and nonspecific immune modulation.

scholarly journals Deciphering the Translation Initiation Factor 5A Modification Pathway in Halophilic Archaea

Archaea ◽  
2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Laurence Prunetti ◽  
Michael Graf ◽  
Ian K. Blaby ◽  
Lauri Peil ◽  
Andrea M. Makkay ◽  
...  
Keyword(s):  
Translation Initiation ◽  
Halophilic Archaea ◽  
Arginine Decarboxylase ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Polyamine Metabolism ◽  
Metabolic Reconstruction ◽  
Deoxyhypusine Synthase

Translation initiation factor 5A (IF5A) is essential and highly conserved in Eukarya (eIF5A) and Archaea (aIF5A). The activity of IF5A requires hypusine, a posttranslational modification synthesized in Eukarya from the polyamine precursor spermidine. Intracellular polyamine analyses revealed that agmatine and cadaverine were the main polyamines produced inHaloferax volcaniiin minimal medium, raising the question of how hypusine is synthesized in this halophilic Archaea. Metabolic reconstruction led to a tentative picture of polyamine metabolism and aIF5A modification inHfx. volcaniithat was experimentally tested. Analysis of aIF5A fromHfx. volcaniiby LC-MS/MS revealed it was exclusively deoxyhypusinylated. Genetic studies confirmed the role of the predicted arginine decarboxylase gene(HVO_1958)in agmatine synthesis. The agmatinase-like gene(HVO_2299)was found to be essential, consistent with a role in aIF5A modification predicted by physical clustering evidence. Recombinant deoxyhypusine synthase (DHS) fromS. cerevisiaewas shown to transfer 4-aminobutyl moiety from spermidine to aIF5A fromHfx. volcanii in vitro.However, at least under conditions tested, this transfer was not observed with theHfx. volcaniiDHS. Furthermore, the growth ofHfx. volcaniiwas not inhibited by the classical DHS inhibitor GC7. We propose a model of deoxyhypusine synthesis inHfx. volcaniithat differs from the canonical eukaryotic pathway, paving the way for further studies.

Inhibition of cell growth through inactivation of eukaryotic translation initiation factor 5A (eIF5A) by deoxyspergualin

2002 ◽  
Vol 363 (3) ◽  
pp. 761-768 ◽  
Author(s):  
Kazuhiro NISHIMURA ◽  
Yuji OHKI ◽  
Tomomi FUKUCHI-SHIMOGORI ◽  
Kaori SAKATA ◽  
Kan SAIGA ◽  
...  
Keyword(s):  
Cell Growth ◽  
Translation Initiation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Deoxyhypusine Synthase ◽  
Eukaryotic Translation Initiation Factor ◽  
Free System ◽  
Eukaryotic Translation ◽  
Mechanism Of Inhibition ◽  
Eukaryotic Translation Initiation

The mechanism of inhibition of cell growth by deoxyspergualin was studied using mouse mammary carcinoma FM3A cells. Results of studies using deoxyspergualin analogues showed that both the guanidinoheptanate amide and glyoxyspermidine moieties of deoxyspergualin were necessary to cause inhibition of cell growth. When deoxyspergualin was added to the medium, there was a strong inhibition of cell growth and formation of active eukaryotic translation initiation factor 5A (eIF5A) at the third day of culture. There was also a marked decrease in cellular putrescine content and a small decrease in spermidine content. Accumulation of decapped mRNA, which is typically associated with eIF5A deficiency in yeast, was also observed. The inhibition of cell growth and the formation of active eIF5A was not reversed by addition of spermidine. The activity of deoxyhypusine synthase, the first enzyme in the formation of active eIF5A, was inhibited by deoxyspergualin in a cell-free system. These results, taken together, indicate that inhibition of active eIF5A formation is strongly involved in the inhibition of cell growth by deoxyspergualin.

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