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1.
Foods ; 13(10)2024 May 13.
Article in English | MEDLINE | ID: mdl-38790815

ABSTRACT

This study evaluated the effect of free and nanoencapsulated rosemary essential oil (REO) as an antibiotic alternative in broiler diets on growth performance, nutrient digestibility, carcass traits, meat quality and gene expression. Four hundred twenty day-old commercial broiler chicks (VENCOBB) were randomly allocated to seven dietary treatments, each having four replicates of fifteen chicks. The dietary treatments comprised control (CON) fed a basal diet only, AB (basal diet + 10 mg enramycin/kg), CS (basal diet + 150 mg chitosan nanoparticles/kg), REOF100 and REOF200 (basal diet + 100 mg and 200 mg free REO/kg, respectively), and REON100 and REON200 (basal diet + 100 mg and 200 mg nanoencapsulated REO/kg, respectively). Overall (7-42 d), REON200 showed the highest (p < 0.001) body weight gain (1899 g/bird) and CON had the lowest gain (1742 g/bird), while the CS, REOF100 and REOF200 groups had a similar gain, but lower than that of the AB and REON100 groups. Feed intake was not affected by dietary treatments. Overall, the feed efficiency increased (p = 0.001) by 8.47% in the REON200 group and 6.21% in the AB and REON100 groups compared with the CON. Supplementation of REO improved (p < 0.05) dry matter and crude protein digestibility, with the highest values in REON100 and REON200. Ether extract, crude fiber, calcium and phosphorus digestibility values showed no difference among the groups. The dressing, breast, thigh % increased (p < 0.05) and abdominal fat % decreased (p < 0.001) more in the REON200 group than with other treatments and CON. In breast meat quality, water holding capacity and extract reserve volume increased (p < 0.05) while drip loss and cholesterol content decreased (p < 0.05) in REON100 and REON200. No change was observed in the breast meat color among dietary treatments and CON. The REON100 and REON200 groups had reduced (p < 0.05) meat lipid peroxidation as depicted by the decreased levels of TBARS, free fatty acids and peroxide value compared to other treatments and CON. The expression of the Mucin 2, PepT1 and IL-10 genes was upregulated (p < 0.001) and TNF-α downregulated (p < 0.001) by dietary addition of REO particularly in the nanoencapsulated form compared with the CON. In conclusion, nanoencapsulated REO, especially at 200 mg/kg diet, showed promising results as an antibiotic alternative in improving the performance, nutrient digestibility, carcass traits, meat quality and upregulation of growth and anti-inflammatory genes.

2.
Anim Biotechnol ; 33(7): 1620-1628, 2022 Dec.
Article in English | MEDLINE | ID: mdl-34057400

ABSTRACT

The objective of this study was to investigate the effects of feeding rice gluten meal (RGM) as an alternative protein source along with protease enzyme supplementation on growth performance, expression of nutrient transporter genes, nutrient digestibility, immune response and gut histomorphometry of broiler chicken. Proximate analysis of RGM revealed 923 g dry matter (DM), 500 g crude protein (CP), 69.2 g ether extract, 94.7 g crude fiber, 215.4 g nitrogen-free extract, 43.7 g ash, 6.20 g calcium, 7.80 g total phosphorus, 18.99 MJ gross energy and 12.68 MJ metabolizable energy per kg diet. Significant upregulation of nutrient transporter genes (PepT1, EAAT3 and mucin) and better growth performance was observed in the birds fed control diet which was statistically similar to the birds fed 150 g RGM compared to birds fed higher RGM levels. Histomorphometry of jejunum, nutrient digestibility, and immune response of birds did not reveal any significant effect of RGM or protease enzyme supplementation. However, the inclusion of RGM up to 150 g/kg diet resulted in significant decline of feed cost/kg live weight gain, dressed meat yield and eviscerated meat yield by 13.13%, 12.99% and 13.36%, respectively compared to control. Thus, it was concluded that the inclusion of 150 g RGM/kg diet in broiler chicken ration has no adverse effects on the growth pattern of birds and can be used for least-cost feed formulation for chicken.


Subject(s)
Chickens , Oryza , Animals , Jejunum , Glutens/metabolism , Diet/veterinary , Peptide Hydrolases/genetics , Peptide Hydrolases/metabolism , Peptide Hydrolases/pharmacology , Nutrients , Dietary Supplements , Animal Feed/analysis
3.
Environ Sci Pollut Res Int ; 29(12): 18271-18281, 2022 Mar.
Article in English | MEDLINE | ID: mdl-34687416

ABSTRACT

The coronavirus disease 2019 (COVID-19) is an ongoing pandemic with high morbidity and mortality rates. Current epidemiological studies urge the need of implementing sophisticated methods to appraise the evolution of COVID-19. In this study, we analysed the data for 228 days (1 May to 15 December 2020) of daily incidence of COVID-19 cases for a district level analysis in the region of Jammu and Kashmir in the northern Himalayan belt of India. We used a deep learning-based incremental learning technique to model the current trend of COVID-19 transmission and to predict the future trends with 60-day forecasting. The results not only indicate high rates of morbidity and mortality but also forecast high rise in the incidence of COVID-19 in different districts of the study region. We used geographic information system (GIS) for storing, analysing, and presenting the spread of COVID-19 which provides key insights in understanding, planning, and implementing mitigating measures to tackle the current spread of the pandemic and its possible future scenarios. The existing disparity in health care facilities at district level is shown in relation to the spread of disease. The study results also highlight the need to upgrade health care infrastructure in the study region to control the current and future pandemics. These results could be useful for administration and scientific community to develop efficient short-term and long-term strategies against such diseases.


Subject(s)
COVID-19 , Deep Learning , COVID-19/epidemiology , Humans , India/epidemiology , Pandemics , Risk Assessment , SARS-CoV-2
4.
Environ Sci Pollut Res Int ; 28(48): 68600-68614, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34275076

ABSTRACT

The studies related to air pollutants and their association with human health over the mountainous region are of utmost importance and are sparse especially over the Himalayan region of India. The linkages between various atmospheric variables and clinically validated data have been done using various datasets procured from satellite, model reanalysis, and surface observations during 2013-2017. Aerosol optical depth, air temperature, and wind speed are significantly related (p < 0.001) to the incidence of acute respiratory infections with its peak during winter. Model-derived particulate matter (PM2.5) shows high contributions of black carbon, organic carbon, and sulfate during winter. The wind roses show the passage of winds from the south-west and southern side of the region. Back trajectory density plot along with bivariate polar plot analyses have shown that most of the winds coming from the western side are taking a southward direction before reaching the study area and may be bringing pollutants from the Indo-Gangetic Plain and other surrounding regions. Our study shows that the accumulation of pollutants in the Himalayan valley is owing to the meteorological stability with significant local emissions from burning of biomass and biofuels along with long-range and mid-range transport during the winter season that significantly correlated with the incidence of acute respiratory infections in the region.


Subject(s)
Air Pollutants , Air Pollution , Respiratory Tract Infections , Aerosols/analysis , Air Pollutants/analysis , Air Pollution/analysis , Environmental Monitoring , Humans , India , Particulate Matter/analysis , Respiratory Tract Infections/epidemiology , Seasons
5.
J Clin Exp Hepatol ; 10(6): 590-598, 2020.
Article in English | MEDLINE | ID: mdl-33311896

ABSTRACT

BACKGROUND/PURPOSE: Hepatitis B virus reactivation (HBVR) is common in patients withcancer. The aim of the present study was to find out clinical profile of patients with cancer receiving chemotherapy with HBVR and to study the efficacy of entecavir (ETV) and tenofovir in the treatment of HBVR. METHODS: This is a prospective study in which all consecutive patients with cancer with evidence of HBVR were included. HBVR was defined as: New onset transaminitis with alanine aminotransferase (ALT) >3 times upper limit of normal and >10 fold increase in HBV DNA levels from baseline levels or detection of HBV DNA ≥100,000 IU/ml in patients with no baseline HBV DNA. Patients with HBVR were put on ETV or tenofovir and were closely monitored for efficacy and safety for minimum of 1 year. RESULTS: Of 204 Hepatitis B surface antigen (HBsAg)-positive patients with different cancers, 92 met the inclusion criteria. Of 92, 46 received ETV 0.5 mg/day and 46 received tenofovir disoproxil fumarate (TDF) 300 mg/day. At 6 months, there was 4.7 log reduction in HBV DNA level in the ETV group and 5.2 log reduction in the TDF group (P = 0.029). Proportion of patients with undetectable HBV DNA (75.7% vs 87.5%), ALT normalization (89.2% Vs 87.5%), HBsAg negativity (25% vs 28.1%), and seroconversion (2.8% vs 3.1%) at 1 year were almost similar in both groups with P value > 0.05 for all efficacy end points. There was no HBVR-related mortality in any group. CONCLUSION: Both ETV and tenofovir are very effective in the treatment of HBVR and reduce the liver-related mortality and morbidity in such patients.

6.
J Clin Exp Hepatol ; 10(2): 150-154, 2020.
Article in English | MEDLINE | ID: mdl-32189930

ABSTRACT

OBJECTIVE: Hepatitis B infection is common in patients with cancer, and prompt treatment is necessary; otherwise, it can result in life-threatening complications. The objective of this study was to assess the long-term safety and efficacy of entecavir in immunocompromised children with hepatitis B. METHODS: This single-center prospective study was conducted on children with different malignancies referred to our department with evidence of hepatitis B infection. Only those children were included in the study who had HBsAg positive and alanine aminotransferase (ALT) more than 2 times the upper limit of normal and whose hepatitis B virus (HBV) DNA was more than 20,000IU/ml. These children were put on entecavir and prospectively observed upto 192 weeks. Primary efficacy end point was the proportion of patients who achieved undetectable HBV DNA at 48 weeks of treatment. Other efficacy end points were the proportion of patients with HBeAg seroconversion, undetectable HBV DNA, and ALT normalization at weeks 48 and 96 weeks. RESULTS: A total of 41 children met the inclusion criteria, of which 5 children died because of malignancy and 5 were lost to follow-up. Mean log DNA was 7.67 at the start which after starting entecavir reduced to 4.1, 2.8, 1.19, 1.09, and 0.84 at 12, 24, 48, 72, and 96 weeks, respectively (P value < 0.0001). Mean ALT decreased from 332.5 which reduced to 190, 115, 63, and 46 at 4, 12, 24, and 48 weeks, respectively (P < 0.0001). 67.7% achieved the primary outcome and had undetectable DNA at 48 weeks which increased to 26 (83.9%) at 96 weeks. At 48 weeks, 80.6% patients achieved ALT normalization. Thirty percent developed HBeAg seroconversion. Two patients developed virological breakthrough, one at 96 weeks and another at 192 weeks. No significant adverse effects were observed. CONCLUSION: Entecavir is safe and effective in long term for the treatment of hepatitis B in immunocompromised children.

7.
Exp Biol Med (Maywood) ; 233(5): 603-9, 2008 May.
Article in English | MEDLINE | ID: mdl-18375831

ABSTRACT

FcRn, a nonclassical MHC-I protein bound to beta 2-microglobulin (beta 2m), diverts IgG and albumin from an intracellular degradative fate, prolonging the half-lives of both. While knockout mouse strains lacking either FcRn-alpha-chain (AK) or beta 2m (BK) show much shorter half-lives of IgG and albumin than normal mice, the plasma IgG half-life in the BK and AK strains is different, being shorter in the BK strain. Since beta 2m does not affect the IgG production rate, we tested whether an additional beta 2m-associated mechanism protects IgG from catabolism. First, we compared the fractional disappearance rate in plasma of an intravenous dose of radioiodinated IgG in a mouse strain deficient in both FcRn-alpha-chain and beta 2m (ABK), in the two parental knockout strains (AK and BK), and in the background wild-type (WT) strain. We found that IgG survived longer in the beta 2m-expressing AK strain than in the beta 2m-lacking ABK and BK strains, whereas the IgG half-lives between the ABK and BK strains were identical. Then we compared endogenous concentrations of four typical plasma proteins among the four strains and found that steady-state plasma concentrations of both IgG and albumin were higher in the AK strain than in either the BK or the ABK strain. These results suggest that a beta 2m-associated effect other than FcRn prolongs the survival of both IgG and albumin, although leaky gene transcription in the AK strain cannot be ruled out.


Subject(s)
Histocompatibility Antigens Class I/metabolism , Immunoglobulin G/immunology , Immunoglobulin G/metabolism , Receptors, Fc/deficiency , Receptors, Fc/metabolism , beta 2-Microglobulin/deficiency , beta 2-Microglobulin/metabolism , Animals , Histocompatibility Antigens Class I/genetics , Histocompatibility Antigens Class I/immunology , Immunoglobulin A/blood , Immunoglobulin A/immunology , Mice , Mice, Inbred C57BL , Mice, Knockout , Receptors, Fc/genetics , Receptors, Fc/immunology , Time Factors , beta 2-Microglobulin/genetics
8.
J Nutr ; 136(12): 2993-8, 2006 Dec.
Article in English | MEDLINE | ID: mdl-17116709

ABSTRACT

HFE, a major histocompatibility complex class I-related protein, is implicated in the iron overload disease, hereditary hemochromatosis. Whereas patients with hereditary hemochromatosis have low serum transferrin levels, little is known about transferrin turnover in HFE deficiency states. We injected mice intravenously with radioiodinated transferrin and compared plasma transferrin decay and steady-state endogenous transferrin concentration in the plasma between HFE-deficient and wild-type C57BL/6 mouse strains. HFE-deficient mice degraded transferrin faster than normal (P < 0.001) and had lower plasma transferrin concentrations (P < 0.001). Both HFE-deficient and wild-type mice were then fed diets with 3 different iron concentrations that we designated deficient (2-5 mg/kg of iron), control (0.2 g/kg), and overload (20 g/kg) for 6 wk immediately after weaning to create a range of serum iron concentrations and resultant transferrin saturations ranging from 16 to 78%. We found an inverse correlation between transferrin saturation and transferrin half-life (P < 0.0001, r = -0.839) for both HFE-deficient and wild-type mice, which suggests that HFE does not have a direct effect on transferrin catabolism; rather, HFE may influence transferrin half-life indirectly through its effect on transferrin saturation, which in turn enhances transferrin decay in HFE-deficient mice.


Subject(s)
Membrane Proteins/deficiency , Transferrin/metabolism , Animal Feed , Animals , Hemochromatosis Protein , Histocompatibility Antigens Class I , Immunoglobulin A/metabolism , Kinetics , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Proteinuria , Reference Values , Transferrin/pharmacokinetics
9.
Trends Immunol ; 27(7): 343-8, 2006 Jul.
Article in English | MEDLINE | ID: mdl-16731041

ABSTRACT

Recent evidence validates a forgotten 40-year-old hypothesis: the MHC-related Fc receptor for IgG (FcRn) protects albumin from intracellular catabolic degradation, as it does for IgG, accounting for the uniquely long half-lives of both molecules and explaining their direct concentration-catabolism relationships. Albumin and IgG bind to FcRn at low pH but not at physiological pH. These two ligands bind independently of one another by distinctive mechanisms and to different surfaces of the receptor. Kinetic studies of FcRn-deficient mice indicate that, at steady-state, FcRn salvages from the degradative pathway a similar amount of albumin as is produced by mice and almost four-times more IgG than is produced. Thirty-fivefold more albumin than IgG molecules are protected from degradation by FcRn per unit time. It can be inferred that FcRn is expressed in nearly all cells. This receptor, originally described as transporting IgG from the mother to the fetus or neonate, now has a wider role central to the homeostatic regulation and conservation of both albumin and IgG throughout life.


Subject(s)
Receptors, IgG/metabolism , Serum Albumin/metabolism , Animals , Biological Transport, Active , Humans , Immunoglobulin G/metabolism
10.
Proc Natl Acad Sci U S A ; 103(13): 5084-9, 2006 Mar 28.
Article in English | MEDLINE | ID: mdl-16549777

ABSTRACT

Two siblings, products of a consanguineous marriage, were markedly deficient in both albumin and IgG because of rapid degradation of these proteins, suggesting a lack of the neonatal Fc receptor, FcRn. FcRn is a heterodimeric receptor composed of a nonclassical MHC class I alpha-chain and beta(2)-microglobulin (beta(2)m) that binds two ligands, IgG and albumin, and extends the catabolic half-lives of both. Eight relatives of the siblings were moderately IgG-deficient. From sera archived for 35 years, we sequenced the two siblings' genes for the heterodimeric FcRn. We found that, although the alpha-chain gene sequences of the siblings were normal, the beta(2)m genes contained a single nucleotide transversion that would mutate a conserved alanine to proline at the midpoint of the signal sequence. Concentrations of soluble beta(2)m and HLA in the siblings' sera were <1% of normal. Transfection assays of beta(2)m-deficient cultured cells with beta(2)m cDNA indicated that the mutant beta(2)m supported <20% of normal expression of beta(2)m, MHC class I, and FcRn proteins. We concluded that a beta(2)m gene mutation underlies the hypercatabolism and reduced serum levels of albumin and IgG in the two siblings with familial hypercatabolic hypoproteinemia. This experiment of nature affirms our hypothesis that FcRn binds IgG and albumin, salvages both from a degradative fate, and maintains their physiologic concentrations.


Subject(s)
Histocompatibility Antigens Class I/metabolism , Hypoproteinemia/genetics , Hypoproteinemia/metabolism , Receptors, Fc/deficiency , Receptors, Fc/metabolism , beta 2-Microglobulin/genetics , beta 2-Microglobulin/metabolism , Amino Acid Sequence , Base Sequence , Cell Line, Tumor , Disease Susceptibility , Gene Expression Regulation , Histocompatibility Antigens Class I/genetics , Humans , Hypoproteinemia/pathology , Molecular Sequence Data , Mutation/genetics , Receptors, Fc/genetics , beta 2-Microglobulin/chemistry
11.
Mol Carcinog ; 42(1): 53-64, 2005 Jan.
Article in English | MEDLINE | ID: mdl-15547920

ABSTRACT

The ubiquitin-proteasome pathway is fundamental to synchronized continuation of many cellular processes, for example, cell-cycle progression, stress response, and cell differentiation. Recent studies have shown that the ubiquitin-proteasome pathway functions in the regulation of nucleotide excision repair (NER) in yeast. In order to investigate the role of the ubiquitin-proteasome pathway in the NER of mammalian cells, global genomic repair (GGR), and transcription-coupled repair (TCR) were examined in a mouse ts20 cell line that harbors a temperature-sensitive ubiquitin-activating enzyme (E1). We found that E1 inactivation-induced ubiquitination deficiency decreased both GGR and TCR, indicating that the ubiquitination system is involved in the optimization of entire NER machinery in mammalian cells. We specifically inhibited the function of 19S proteasome subunit by overexpressing 19S regulatory complex hSug1 or its mutant protein hSug1mk in repair competent human fibroblast, OSU-2, cells and compared their capacity for NER. The results showed that 19S regulatory complex positively modulates NER in cells. In addition, we treated OSU-2 cells with the inhibitors of 20S subunit function, MG132 and lactacystin, and demonstrated that the catalytic activity of 20S subunit is also required for efficient NER. Moreover, the UV-induced recruitment of repair factor xeroderma pigmentosum protein C (XPC) to damage sites was negatively affected by treatment of repair competent cells with MG132. Taken together, we conclude that the ubiquitin-proteasome pathway has a positive regulatory role for optimal NER capacity in mammalian cells and appears to act through facilitating the recruitment of repair factors to DNA damage sites.


Subject(s)
DNA Repair/physiology , Proteasome Endopeptidase Complex/metabolism , Ubiquitin/metabolism , ATPases Associated with Diverse Cellular Activities , Adaptor Proteins, Signal Transducing/metabolism , Animals , LIM Domain Proteins , Mice , Proteasome Inhibitors , Time Factors , Transcription Factors/metabolism , Ubiquitin-Activating Enzymes/metabolism
12.
DNA Repair (Amst) ; 2(5): 483-99, 2003 May 13.
Article in English | MEDLINE | ID: mdl-12713809

ABSTRACT

Functional tumor suppressor p53 is mainly required for efficient global genomic repair (GGR), a subpathway of nucleotide excisions repair (NER). In this study, the regulatory effect of p53, on the spaciotemporal recruitment of XPC and TFIIH to DNA damage sites, was investigated in repair-proficient and -deficient human cells in situ. Photoproducts were induced through micropore UV irradiation of discrete subnuclear areas of intact cells and the specific lesions, as well as recruited repair factors, were detected by immunofluorescent intensity and density of the damaged DNA subnuclear spots (SNS). Both cyclobutane pyrimidine dimers (CPD) and 6-4 photoproducts (6-4PP) were visualized in situ at SNS within irradiated nuclear foci. The in situ repair kinetics revealed that p53-WT normal fibroblasts are proficient for the repair of both CPD and 6-4PP, whereas, p53-Null Li-Fraumeni syndrome (LFS) fibroblasts fail to efficiently repair CPD but not 6-4PP. Colocalization experiments of the NER factors showed that in normal human cells, XPC and TFIIH are rapidly and efficiently recruited to DNA damage within SNS. By contrast, recruitment of both XPC and TFIIH to DNA damage in SNS occurred much less efficiently in p53-Null or p53-compromised cells. The total cellular levels of XPC and XPB were similar in both p53-WT and -Null cells and remained unchanged up to 24h following UV irradiation. The results also showed that dispersal of recruited XPC and TFIIH from DNA damage SNS occurs within a short period after DNA damage. Such dispersal requires functional XPA, XPF and XPG proteins. Taken together, the results demonstrated that p53 plays a pronounced role in the damage recognition and subsequent assembly of repair machinery during GGR and the recruitment of XPC and TFIIH to CPD is p53-dependent. Most likely mechanism of this p53 action is through its downstream effector protein, DDB2.


Subject(s)
DNA Damage , DNA Repair , DNA-Binding Proteins/metabolism , Transcription Factors, TFII/metabolism , Tumor Suppressor Protein p53/metabolism , Blotting, Western , Cell Line , Cell Nucleus/metabolism , Chromatin/metabolism , DNA/metabolism , Dimerization , Fibroblasts/metabolism , Humans , Kinetics , Microscopy, Fluorescence , Time Factors , Transcription Factor TFIIH , Ultraviolet Rays
13.
Mutat Res ; 505(1-2): 13-25, 2002 Aug 29.
Article in English | MEDLINE | ID: mdl-12175902

ABSTRACT

Wild-type p53 protein is known to regulate the global genomic repair (GGR), removing bulky chemical DNA adducts as well as cyclobutane pyrimidine dimers from the genome overall and from non-transcribed strands (NTS) in DNA. To investigate the role of cellular factor(s) relevant to p53 regulated DNA repair processes, we examined the repair kinetics of chemical carcinogen, anti-benzo[a]pyrene-diol epoxide (anti-BPDE), induced bulky DNA adducts in normal human mammary epithelial cells (HMECs) and HMEC transformed by human papillomavirus (HPV)-16E6 or -16E7 oncoproteins, which, respectively targets p53 or pRb proteins for degradation. The results show that the removal of anti-BPDE DNA adducts from the genome overall and NTS by GGR was significantly reduced in HPV-16E6 protein expressing cells as compared to that in normal and HPV-16E7 protein expressing cells, indicating the role of p53 and not pRb in nucleotide excision repair (NER). We further determined the potential effects of the p53-regulated p21(waf1/cip1) gene product in NER in human colon carcinoma, HCT116 cells expressing wild-type p53 but different p21(waf1/cip1) genotypes (p21+/+, p21+/-, p21-/-). The results donot show a discernible difference in the removal of anti-BPDE DNA adducts from the genome overall and the transcribed strand (TS) and NTS irrespective of the presence or absence of p21(waf1/cip1) expression. Based on these results, we suggest that: (i) the wild-type p53 function but not p21(waf1/cip1) expression is necessary for GGR of chemical induced bulky DNA adducts; (ii) the Rb gene product does not play a significant role in NER; and (iii) the modulation of NER by p53 may be independent of its function in the regulation of cell cycle arrest upon chemically induced DNA damage.


Subject(s)
7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide/metabolism , Cyclins/physiology , DNA Adducts/metabolism , DNA Repair/physiology , Repressor Proteins , Retinoblastoma Protein/physiology , Tumor Suppressor Protein p53/physiology , Adenocarcinoma/pathology , Breast/cytology , Cell Line, Transformed/drug effects , Cell Transformation, Viral , Colonic Neoplasms/pathology , Cyclin-Dependent Kinase Inhibitor p21 , DNA Adducts/genetics , DNA, Neoplasm/drug effects , Endodeoxyribonucleases/pharmacology , Epithelial Cells/drug effects , Escherichia coli Proteins/pharmacology , Female , Humans , Oncogene Proteins, Viral/physiology , Papillomavirus E7 Proteins , Retinoblastoma Protein/antagonists & inhibitors , Transcription, Genetic/physiology , Tumor Cells, Cultured/drug effects , Tumor Suppressor Protein p53/antagonists & inhibitors
14.
Carcinogenesis ; 23(3): 403-10, 2002 Mar.
Article in English | MEDLINE | ID: mdl-11895854

ABSTRACT

Cancer development requires the accumulation of numerous genetic changes, which are believed to initiate through the presence of unrepaired lesions in the genome. In the absence of proficient repair, genotoxic agents can lead to crucial mutations of vital cellular genes via replication of damaged DNA. Many cell cycle regulatory proteins are known to modulate the repair capacity and consequently the fate of cells. We and others have recently shown that p53 tumor suppressor gene product is required for efficient global genomic repair (GGR) but not the transcription coupled repair (TCR) of the nucleotide excision repair (NER) sub-pathways. In order to discern the nature of the p53 modulation to be direct or indirect through a downstream mediator, we have investigated the processing of UV radiation induced lesions in human colon carcinoma, HCT116 cells expressing wild-type p53 but having different p21(waf1cip1) (hereafter p21) genotypes (p21+/+, p21+/-, p21-/-). Following 20 J/m(2) UV, all the three cell lines showed rapid increase in p53 protein but the accompanying increase in the expression of its downstream target protein p21 could only be seen in p21+/+ and p21+/- cells and not in p21-/- cells. Nevertheless, an absence of detectable p21 protein in deficient cells had no demonstrable effect on DNA repair response to UV irradiation, as measured by an immunoassay to detect removal of UV photoproducts from genomic DNA (GGR) and by individual strand specific removal of endonuclease-sensitive CPD from a target gene fragment (TCR). Introduction of cytomegalovirus (CMV)-driven luciferase reporter plasmid, UV damaged in vitro, into the un-irradiated cells of varying p21 background, revealed a relatively small but statistically significant decrease in the reporter expression in the host p21-/- as compared with p21+/+ and p21+/- HCT116 cells. Super-expression of p21 protein upon reintroduction of p21 expression construct, showed an enhanced recovery of UV damaged reporter activity that was not greatly different from a similar enhancement observed with undamaged plasmid reporter DNA. Taken together, the results indicate that (i) the p21 protein does not have a significant role in the repair of genomic DNA at chromosomal level; (ii) the well-established p53 dependent modulation of NER is distinct and independent of its cell cycle checkpoint function; and (iii) the reproducible enhancing effect of p21 expression observed through host cell reactivation (HCR) of extrachromosomal DNA is mainly attributable to an effect exerted on transcription rather than repair.


Subject(s)
Cyclins/deficiency , Cyclins/metabolism , DNA Damage/radiation effects , DNA Repair/genetics , Tumor Suppressor Protein p53/deficiency , Tumor Suppressor Protein p53/metabolism , Ultraviolet Rays/adverse effects , Cyclin-Dependent Kinase Inhibitor p21 , DNA/analysis , DNA/genetics , DNA Repair/radiation effects , Humans , Pyrimidine Dimers/genetics , Pyrimidine Dimers/radiation effects , Time Factors , Transfection , Tumor Cells, Cultured
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