Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.108 (TAT)
 2,389 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The resounding success of a new immunosuppressive regimen known as the Edmonton protocol demonstrates that islet cell transplantation is becoming a therapeutic reality for diabetes. However, under the Edmonton protocol, a single donor does not provide enough islets to attain the insulin independence of a transplant recipient. This limitation is mainly caused by islet apoptosis triggered during isolation. In this study, we describe a highly efficient system of transiently transferring anti-apoptotic proteins into pancreatic islets, thus opening an exciting new therapeutic opportunity to improve the viability of transplantable islets. We fused beta-galactosidase to the 11-amino acid residues that constitute the protein transduction domain (PTD) of the HIV/TAT protein and transduced pancreatic islets ex vivo with this fusion protein in a dose-dependent manner with >80% efficiency. We observed that transduction of the anti-apoptotic proteins Bcl-X(L) and PEA-15 fused to TAT/PTD prevented apoptosis induced by tumor necrosis factor-alpha in a pancreatic beta-cell line, indicating that TAT/PTD anti-apoptotic proteins retained their biological activity. Finally, we demonstrated that TAT-fusion proteins did not affect the insulin secretion capability of islets, as determined by glucose static incubation and by reversion of hyperglycemia in diabetic immunodeficient mice.
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PMID:Proteins linked to a protein transduction domain efficiently transduce pancreatic islets. 1147 28

The HIV TAT protein contains an 11-amino-acid protein transduction domain which acts as a "Trojan peptide": Linked to other macromolecules, it carries them across cellular membranes. Here, we demonstrate for the first time that fusion of the TAT protein transduction domain to an antiapoptotic protein represents a feasible technique to rescue neurons from apoptotic degeneration in vitro and in vivo. When fused to the antiapoptotic protein Bcl-X(L), it mediated uptake of the fusion protein into neurons. Once inside the cells, TAT-Bcl-X(L) was stable for many days and maintained its antiapoptotic function. It completely blocked low-potassium-induced apoptosis of cerebellar granule cells in vitro. In vivo, 24% of mouse retinal ganglion cells were prevented from undergoing retrograde neuronal apoptosis caused by optic nerve lesion when TAT-Bcl-X(L) was intraocularly injected. The application of TAT fusion proteins may in the future greatly facilitate neuroprotective therapy strategies for neurological disorders.
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PMID:Inhibition of neuronal apoptosis in vitro and in vivo using TAT-mediated protein transduction. 1235 49

The delivery of proteins across the blood-brain barrier is severely limited by the proteins' size and biochemical properties. Eleven-amino acid human immunodeficiency virus TAT protein is able to cross cell membranes even when coupled with larger peptides. We evaluated whether TAT-Bcl-X(L) fusion protein is protective in focal ischemia. Mice underwent 30 or 90 minutes of intraluminal middle cerebral artery thread occlusion. TAT-Bcl-X(L), TAT-beta-galactosidase, or TAT-GFP (0.6 nmol each) were applied intravenously over 10 minutes either 1 hour before or immediately after ischemia. Additional animals received no TAT protein infusions. We show that the brain tissue is progressively transduced with TAT proteins within 3 to 4 hours after intravenous delivery. We provide evidence that TAT-Bcl-X(L) treatment reduces infarct volume and neurological deficits after long ischemic insults lasting 90 minutes, when applied both before and after ischemia. After short insults, lasting only 30 minutes, TAT-Bcl-X(L) further diminishes the number of caspase-3-reactive and DNA fragmented cells and increases the number of viable neurons in the striatum. Our results indicate that TAT fusion proteins are elegant and powerful tools that might be of clinical interest for stroke treatment, because factors may be intravenously applied. Thus, fusion proteins may open fascinating perspectives for future research.
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PMID:Intravenous TAT-Bcl-Xl is protective after middle cerebral artery occlusion in mice. 1240 59

Opposite effects of nuclear factor-kappaB (NF-kappaB) on neuron survival rely on activation of diverse NF-kappaB factors. While p65 is necessary for glutamate-induced cell death, c-Rel mediates prosurvival effects of interleukin-1beta. However, it is unknown whether activation of c-Rel-dependent pathways reduces neuron vulnerability to amyloid-beta (Abeta), a peptide implicated in Alzheimer's disease pathogenesis. We show that neuroprotection elicited by activation of metabotropic glutamate receptors type 5 (mGlu5) against Abeta toxicity depends on c-Rel activation. Abeta peptide induced NF-kappaB factors p50 and p65. The mGlu5 agonists activated c-Rel, besides p50 and p65, and the expression of manganese superoxide dismutase (MnSOD) and Bcl-X(L). Targeting c-Rel expression by RNA interference suppressed the induction of both antiapoptotic genes. Targeting c-Rel or Bcl-X(L) prevented the prosurvival effect of mGlu5 agonists. Conversely, c-Rel overexpression or TAT-Bcl-X(L) addition rescued neurons from Abeta toxicity. These data demonstrate that mGlu5 receptor activation promotes a c-Rel-dependent antiapoptotic pathway responsible for neuroprotection against Abeta peptide.
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PMID:NF-kappaB factor c-Rel mediates neuroprotection elicited by mGlu5 receptor agonists against amyloid beta-peptide toxicity. 1581 10

Severe brain damage in patients with pneumococcal meningitis is in part caused by the cytosolic pneumococcal protein pneumolysin. The devastating effect of this neurotoxin might be alleviated by interfering with the cell death pathways that it sets in motion. An important player in these pathways is Bcl-X(L), an antiapoptotic protein of the Bcl-2 family, which is neuroprotective in various in vitro and in vivo models of cell death. We investigated whether its membrane-permeable form, the TAT-Bcl-X(L) fusion protein, is capable of protecting human SH-SY5Y neuroblastoma cells against pneumolysin-induced cell death. Under mild pneumolysin-induced neuronal injury, TAT-Bcl-X(L) increased cell viability significantly by approximately 40% (82.7 +/- 16.1% versus 70.0+/-8.2%; p = 0.04). When the cells were exposed to a more rigorous pneumolysin treatment, TAT-Bcl-X(L) had no protective effects. This suggests the involvement of additional neuronal death pathways in pneumolysin-induced cell death, which are not controlled by Bcl-X(L). Therefore, Bcl-X(L), a promising therapeutic candidate for ischemia and neurodegenerative diseases, is only of partial efficacy in preventing the direct neurotoxicity of pneumolysin.
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PMID:Limited protection of TAT-Bcl-X(L) against pneumolysin-induced neuronal cell death. 1596 Dec 28

When fused with the protein transduction domain (PTD) derived from the human immunodeficiency virus TAT protein, proteins can cross the blood-brain barrier and cell membrane and transfer into several tissues, including the brain, making protein therapy feasible for various neurological disorders. We have constructed a powerful antiapoptotic modified Bcl-X(L) protein (originally constructed from Bcl-X(L)) fused with PTD derived from TAT (TAT-modified Bcl-X(L)), and, to examine its clinical effectiveness in a mouse model of familial amyotrophic lateral sclerosis (ALS), transgenic mice expressing human Cu/Zn superoxide dismutase (SOD1) bearing a G93A mutation were treated by intrathecal infusion of TAT-modified Bcl-X(L). We demonstrate that intrathecally infused TAT-fused protein was effectively transferred into spinal cord neurons, including motor neurons, and that intrathecal infusion of TAT-modified Bcl-X(L) delayed disease onset, prolonged survival, and improved motor performance. Histological studies show an attenuation of motor neuron loss and a decrease in the number of cleaved caspase 9-, cleaved caspase 3-, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells in the lumbar cords of TAT-modified Bcl-X(L)-treated G93A mice. Our results indicate that intrathecal protein therapy using a TAT-fused protein is an effective clinical tool for the treatment of ALS.
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PMID:Therapeutic benefits of intrathecal protein therapy in a mouse model of amyotrophic lateral sclerosis. 1854 36

Ablation of mouse occipital cortex induces precisely timed and uniform p53-modulated and Bax-dependent apoptosis of thalamocortical projection neurons in the dorsal lateral geniculate nucleus (LGN) by 7 d after lesion. We tested the hypothesis that this neuronal apoptosis is initiated by oxidative stress and the mitochondrial permeability transition pore (mPTP). Preapoptotic LGN neurons accumulate mitochondria, Zn(2+) and Ca(2+), and generate higher levels of reactive oxygen species (ROS), including superoxide, nitric oxide (NO), and peroxynitrite, than LGN neurons with an intact cortical target. Preapoptosis of LGN neurons is associated with increased formation of protein carbonyls, protein nitration, and protein S-nitrosylation. Genetic deletion of nitric oxide synthase 1 (nos1) and inhibition of NOS1 with nitroindazole protected LGN neurons from apoptosis, revealing NO as a mediator. Putative components of the mPTP are expressed in mouse LGN, including the voltage-dependent anion channel (VDAC), adenine nucleotide translocator (ANT), and cyclophilin D (CyPD). Nitration of CyPD and ANT in LGN mitochondria occurs by 2 d after cortical injury. Chemical cross-linking showed that LGN neuron preapoptosis is associated with formation of CyPD and VDAC oligomers, consistent with mPTP formation. Mice without CyPD are rescued from neuron apoptosis as are mice treated with the mPTP inhibitors TRO-19622 (cholest-4-en-3-one oxime) and TAT-Bcl-X(L)-BH4. Manipulation of the mPTP markedly attenuated the early preapoptotic production of reactive oxygen/nitrogen species in target-deprived neurons. Our results demonstrate in adult mouse brain neurons that the mPTP functions to enhance ROS production and the mPTP and NO trigger apoptosis; thus, the mPTP is a target for neuroprotection in vivo.
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PMID:The mitochondrial permeability transition pore regulates nitric oxide-mediated apoptosis of neurons induced by target deprivation. 2120 22

Collective evidence indicates that motor neuron degeneration in amyotrophic lateral sclerosis (ALS) is non-cell-autonomous and requires the interaction with the neighboring astrocytes. Recently, we reported that a subpopulation of spinal cord astrocytes degenerates in the microenvironment of motor neurons in the hSOD1(G93A) mouse model of ALS. Mechanistic studies in vitro identified a role for the excitatory amino acid glutamate in the gliodegenerative process via the activation of its inositol 1,4,5-triphosphate (IP(3))-generating metabotropic receptor 5 (mGluR5). Since non-physiological formation of IP(3) can prompt IP(3) receptor (IP(3)R)-mediated Ca(2+) release from the intracellular stores and trigger various forms of cell death, here we investigated the intracellular Ca(2+) signaling that occurs downstream of mGluR5 in hSOD1(G93A)-expressing astrocytes. Contrary to wild-type cells, stimulation of mGluR5 causes aberrant and persistent elevations of intracellular Ca(2+) concentrations ([Ca(2+)](i)) in the absence of spontaneous oscillations. The interaction of IP(3)Rs with the anti-apoptotic protein Bcl-X(L) was previously described to prevent cell death by modulating intracellular Ca(2+) signals. In mutant SOD1-expressing astrocytes, we found that the sole BH4 domain of Bcl-X(L), fused to the protein transduction domain of the HIV-1 TAT protein (TAT-BH4), is sufficient to restore sustained Ca(2+) oscillations and cell death resistance. Furthermore, chronic treatment of hSOD1(G93A) mice with the TAT-BH4 peptide reduces focal degeneration of astrocytes, slightly delays the onset of the disease and improves both motor performance and animal lifespan. Our results point at TAT-BH4 as a novel glioprotective agent with a therapeutic potential for ALS.
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PMID:The BH4 domain of Bcl-X(L) rescues astrocyte degeneration in amyotrophic lateral sclerosis by modulating intracellular calcium signals. 2207 91