Insulin inhibits glucagon gene transcription, and insulin deficiency is associated with hyperglucagonemia that contributes to hyperglycemia in diabetes mellitus. However, the insulin signaling ...pathway to the glucagon gene is unknown. Protein kinase B (PKB) is a key regulator of insulin signaling and glucose homeostasis. Impaired PKB function leads to insulin resistance and diabetes mellitus. Therefore, the role of PKB in the regulation of glucagon gene transcription was investigated. After transient transfections of glucagon promoter-reporter genes into a glucagon-producing islet cell line, the use of kinase inhibitors indicated that the inhibition of glucagon gene transcription by insulin depends on phosphatidylinositol (PI) 3-kinase. Furthermore, insulin caused a PI 3-kinase-dependent phosphorylation and activation of PKB in this cell line as revealed by phospho-immunoblotting and kinase assays. Overexpression of constitutively active PKB mimicked the effect of insulin on glucagon gene transcription. Both insulin and PKB responsiveness of the glucagon promoter were abolished when the binding sites for the transcription factor Pax6 within the G1 and G3 promoter elements were mutated. Recruitment of Pax6 or its potential coactivator, the CREB-binding protein (CBP), to G1 and G3 by using the GAL4 system restored both insulin and PKB responsiveness. These data suggest that insulin inhibits glucagon gene transcription by signaling via PI 3-kinase and PKB, with the transcription factor Pax6 and its potential coactivator CBP being critical components of the targeted promoter-specific nucleoprotein complex. The present data emphasize the importance of PKB in insulin signaling and glucose homeostasis by defining the glucagon gene as a novel target gene for PKB.
Regulation of gene transcription is an important aspect of insulin's action. However, the mechanisms involved are poorly understood. Insulin inhibits glucagon gene transcription, and insulin ...deficiency is associated with hyperglucagonemia that contributes to hyperglycemia in diabetes mellitus. Transfecting glucagon-reporter fusion genes into a glucagon-producing pancreatic islet cell line, a 5′-, 3′-, and internal deletion analysis, and oligonucleotide cassette insertions failed in the present study to identify a single insulin-responsive element in the glucagon gene. They rather indicate that insulin responsiveness depends on the presence of both proximal promoter elements and more distal enhancer-like elements. When the paired domain transcription factor Pax6 binding sites within the proximal promoter element G1 and the enhancer-like element G3 were mutated into GAL4 binding sites, the expression of GAL4-Pax6 and GAL4-VP16 restored basal activity, whereas only GAL4-Pax6 restored also insulin responsiveness. Likewise, GAL4-CBP activity was inhibited by insulin within the glucagon promoter context. The results suggest that insulin responsiveness is conferred to the glucagon gene by the synergistic interaction of proximal promoter and more distal enhancer-like elements, with Pax6 and its potential coactivator the CREB-binding protein being critical components. These data thereby support concepts of insulin-responsive element-independent mechanisms of insulin action to inhibit gene transcription.
To investigate the global changes accompanying human dilated cardiomyopathy (DCM) we performed a large-scale expression screen using myocardial biopsies from a group of DCM patients with moderate ...heart failure. By hierarchical clustering and functional annotation of the deregulated genes we examined extensive changes in the cellular and molecular processes associated to DCM.
The expression profiles were obtained using a whole genome covering library (UniGene RZPD1) comprising 30336 cDNA clones and amplified RNA from myocardiac biopsies from 10 DCM patients in comparison to tissue samples from four non-failing, healthy donors.
By setting stringent selection criteria 364 differentially expressed, sequence-verified non-redundant transcripts were identified with a false discovery rate of <0.001. Numerous genes and ESTs were identified representing previously recognised, as well as novel DCM-associated transcripts. Many of them were found to be upregulated and involved in cardiomyocyte energetics, muscle contraction or signalling. Two hundred and twenty-two deregulated transcripts were functionally annotated and hierarchically clustered providing an insight into the pathophysiology of DCM. Data was validated using the MLP-deficient mouse, in which several differentially expressed transcripts identified in the human DCM biopsies could be confirmed.
We report the first genome-wide expression profile analysis using cardiac biopsies from DCM patients at various stages of the disease. Although there is a diversity of links between the cytoskeleton and the initiation of DCM, we speculate that genes implicated in intracellular signalling and in muscle contraction are associated with early stages of the disease. Altogether this study represents the most comprehensive and inclusive molecular portrait of human cardiomyopathy to date.
A pancreatic islet cell-specific enhancer
sequence (PISCES) shared by the rat insulin-I, glucagon, and
somatostatin genes binds the paired domain-containing transcription
factor Pax6 and confers ...strong transcriptional activity in pancreatic
islet cell lines. It was found recently that Pax6 plays a major role in
islet development. In the present study, transgenic mice were used to
investigate PISCES-mediated transcription in normal adult islets
in vivo. In several independent mouse lines expressing a
PISCES-luciferase reporter transgene, the PISCES motif directed gene
expression in the adult eye, cerebellum, and discrete brain areas,
consistent with the tissue distribution of Pax6. These tissues contain
two Pax6 isoforms caused by alternative splicing, only one of which was
found to bind the PISCES motif in electrophoretic mobility shift
assays. No reporter gene expression was detected in adult pancreatic
islets or in any other peripheral organ tested. RT-PCR analysis
confirmed that Pax6 mRNA is present in adult islets. These results
demonstrate that the PISCES motif is sufficient to direct highly
tissue-specific gene expression in whole animals. The lack of
PISCES-mediated transcription in adult islets indicates that the Pax6
protein(s) expressed in adult pancreatic islets function differently
from the ones in the eye and cerebellum.
The arginase structural gene (agaA) from Aspergillus nidulans has been cloned and characterised. Depending on the growth conditions of the mycelium, transcripts of this gene have different 5'ends. ...These differences could result either from the presence of multiple transcription initiation sites or from differential processing of mRNA. The agaA mRNA has a long 5'UTR with a potentially complex secondary structure. Putative arginine binding aptamers were found in this UTR suggesting interesting possibilities for regulation of the agaA expression.
Endoscopic sinus surgery can lead to crusting or synechiae formation, which can affect the healing process.
The aim of our study was to compare the influence of steroid versus antibiotic versus ...saline solution impregnated absorbable nasal spacers on postoperative wound healing and patient satisfaction.
Eighty patients, 33 women and 47 men, were enrolled in this study. At the end of the surgery, two pieces of 4cm biodegradable material were applied in each ethmoid cavity. One of them was impregnated with saline solution, while the second one with steroid, or with antibiotic.
We observed statistically significant differences in the Lund–Kennedy score between the control and both treatment groups: for the Antibiotic-group on days 10 and 30 (p=0.009; p=0.009) and for the Steroid-group on day 90 (p=0.008). The extended endoscopic appearance of nasal mucosa indicated statistically significant differences in crust formation on day 10 comparing the steroid and control dressing (p=0.025), in secretion type on days 10 and 30 comparing the antibiotic and control dressing (p=0.003; p=0.016) and additionally for steroid and control on day 90 (p=0.046). On Day 90 we observed statistically significant differences in the absence of mucosal edema in the S-group compared to controls (p=0.007).
The results of this study reveal the significant positive influence of steroid- and antibiotic-impregnated biodegradable nasal packing on the postoperative healing process and patient satisfaction compared to the saline soaked dressing.
A cirurgia endoscópica nasossinusal pode levar à formação de crostas e sinéquias, o que pode afetar o processo de cicatrização.
O objetivo do nosso estudo foi comparar a influência do espaçador nasal absorvível embebido em esteroide versus antibiótico versus solução salina na cicatrização de ferida pós-operatória e na satisfação do paciente.
Oitenta pacientes, 33 mulheres e 47 homens, foram incluídos neste estudo. Ao final da cirurgia, dois tampões de material biodegradável de 4cm foram aplicados em cada cavidade etmoidal. Um deles foi embebido em solução salina, enquanto no segundo foi utilizado esteroide, ou antibiótico.
Observamos diferenças estatisticamente significantes no escore de Lund-Kennedy entre os grupos controle e ambos os grupos tratamentos: para o grupo antibiótico nos dias 10 e 30 (p = 0,009; p = 0,009) e para o grupo esteroide no dia 90 (p = 0,008). O aspecto endoscópico da mucosa nasal indicou diferenças estatisticamente significantes na formação de crostas no dia 10, na comparação do esteroide com o curativo controle (p = 0,025), no tipo de secreção nos dias 10 e 30, na comparação do antibiótico com o curativo controle (p = 0,003; p = 0,016) e adicionalmente para esteroide e controle no dia 90 (p = 0,046). No dia 90, observamos diferenças estatisticamente significantes na ausência de edema da mucosa no grupo E (esteroide) em relação aos controles (p = 0,007).
Os resultados deste estudo revelam uma influência positiva significante no uso de tampão nasal biodegradável embebido em esteroides e antibióticos no processo de cicatrização pós-operatória e satisfação do paciente em comparação com o curativo embebido em solução salina.
Display omitted
•Photocatalysts based on phthalocyanines and TiO2 were prepared.•More efficient photoremediation of naproxen and ibuprofen was achieved.•The zinc(II) phthalocyanine containing ...material was reusable up to 3 times.•The materials were proven safe for use.
Titanium dioxide is extensively researched due to its interesting photoactive properties. One of such is photocatalysis and potential use in photoremediation. New photocatalysts based on titania and metallated phthalocyanines potentially suitable for photodecomposition of environmental pollutants were developed in the presented work. The obtained materials were characterized using various techniques, such as thermogravimetric analysis, X-ray powder diffraction, particle size analysis, electron spin resonance, BET surface area measurements, and scanning electron microscopy. In addition, the photoremediation potential of hybrid materials was studied in ibuprofen and naproxen solutions. During the photocatalytic experiments, it was found that the use of copper(II) phthalocyanine resulted in 92% removal of ibuprofen within six hours, whereas zinc(II) phthalocyanine deposited on titania was able to decompose 94% of naproxen within two hours. Post-reaction solutions were subjected to acute toxicity assay using Microtox. The photocatalysts were found to be non-mutagenic in the Ames test, proving their usefulness and safety in photoremediation.
PDF
