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Wang T, Wang X, Zhang S, Song X, Zhang Y, Tan J, Ren Z, Xu Z, Che T, Yang Y, Nawaz Z. Extreme low air temperature and reduced moisture jointly inhibit respiration in alpine grassland on the Qinghai-Tibetan Plateau. Sci Total Environ 2024; 927:172039. [PMID: 38552977 DOI: 10.1016/j.scitotenv.2024.172039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 03/26/2024] [Accepted: 03/26/2024] [Indexed: 04/09/2024]
Abstract
Alpine grassland is the main vegetation on the Qinghai-Tibetan Plateau (QTP) and exhibits high sensitivity to extreme weather events. With global warming, extreme weather events are projected to become more frequent on the QTP. However, the impact of these extreme weather events on the carbon cycle of alpine grassland remains unclear. The long-term in-situ carbon fluxes data was collected from 2013 to 2022 at an alpine grassland site to examine the impact of extreme low air temperature (ELT) and reduced moisture (including air and soil) on carbon fluxes during the growing season. Our findings indicated that a significant increase in net ecosystem production (NEP) after 2019, with the average NEP increasing from 278.91 ± 43.27 g C m-2 year-1 during 2013-2018 to 415.45 ± 45.29 g C m-2 year-1 during 2019-2022. The ecosystem carbon use efficiency (CUE) increased from 0.38 ± 0.06 during 2013-2018 to 0.62 ± 0.11 during 2019-2022. By combining concurrently measured environmental factors and remote sensing data, we identified the factors responsible for the abrupt change in the NEP after 2019. This phenomenon was caused by an abrupt decrease in ecosystem respiration (Reco) after 2019, which resulted from the inhibition imposed by ELT and reduced moisture. In contrast, gross primary production (GPP) remained stable from 2013 to 2022, which was confirmed by the remotely sensed vegetation index. This study highlights that combined extreme weather events associated with climate change can significantly impact the NEP of alpine grassland, potentially affecting different carbon fluxes at different rates. These findings provide new insights into the mechanisms governing the carbon cycle of alpine grassland.
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Affiliation(s)
- Tonghong Wang
- School of Geography and Environmental Sciences, Northwest Normal University, Lanzhou 730000, China; Key Laboratory of Remote Sensing of Gansu Province, Heihe Remote Sensing Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Xufeng Wang
- Key Laboratory of Remote Sensing of Gansu Province, Heihe Remote Sensing Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Academy of Plateau Science and Sustainability, Qinghai Normal University, Xining 810016, China.
| | - Songlin Zhang
- School of Geography and Environmental Sciences, Northwest Normal University, Lanzhou 730000, China.
| | - Xiaoyu Song
- Key Laboratory of Remote Sensing of Gansu Province, Heihe Remote Sensing Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Yang Zhang
- Key Laboratory of Remote Sensing of Gansu Province, Heihe Remote Sensing Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Junlei Tan
- Key Laboratory of Remote Sensing of Gansu Province, Heihe Remote Sensing Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Zhiguo Ren
- Key Laboratory of Remote Sensing of Gansu Province, Heihe Remote Sensing Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Ziwei Xu
- State Key Laboratory of Remote Sensing Science, School of Geography, Beijing Normal University, Beijing, China
| | - Tao Che
- Key Laboratory of Remote Sensing of Gansu Province, Heihe Remote Sensing Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Yanpeng Yang
- Key Laboratory of Remote Sensing of Gansu Province, Heihe Remote Sensing Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Zain Nawaz
- Department of Geography, Government College University, Faisalabad, Pakistan
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Madni WA, Mohsin M, Nawaz Z, Muzammil S, Zahoor MA, Asif R. Molecular mechanism of antimicrobial co-resistance Colistin (mcr-1) and ESBLs genes among Escherichia coli isolates from commercial chickens in Pakistan. BRAZ J BIOL 2023; 84:e267494. [PMID: 36722678 DOI: 10.1590/1519-6984.267494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 11/30/2022] [Indexed: 02/02/2023] Open
Abstract
Emergence of plasmid mediated colistin and extended spectrum β-lactamases (ESBL) resistant genes has been impacted the efficacy of colistin and β-lactams drugs like 3rd, 4th generation cephalosporin. Current study was aimed to investigate antimicrobial resistance genes (ARGs) among Escherichia coli isolates from meat producing commercial broilers in Pakistan. Two hundred (n=200) fecal samples were collected during January-2018 to August-2019. For isolation of E. coli, pink colonies on MacConkey agar were transferred to EMB agar. Metallic sheen color colonies were tested biochemically using API-20E kit. The molecular identification of E. coli (n=153) was targeted by amplification of uid gene through polymerase chain reaction (PCR) and different ARGs i.e. gentamicin, streptomycin, tetracycline, colistin, β-lactams drugs, quinolone and ampicillin followed by sequence analysis. Genotypically, followed by phenotypically of resistant ARGs of isolated PCR-confirmed E. coli (153) shoed resistant against gentamicin (aac(3)-IV), streptomycin (aadA1), tetracycline (tetA), colistine (mcr-1), ampicillin (bla-TEM) and bla-CTX-M were 86%, 88%, 86%, 88%, 83% & 77% respectively. 33/38 (86%) of the isolate was positive for quinolone resistance. Colistine (mcr-1), ESBLs (bla-TEM) and (bla-CTX-M) resistance genes were 88%, 83% and 77% respectively. About 33 isolated E. coli harbored the both mcr-1 and ESBLs genes. All of E. coli isolates were found sensitive to ceftriaxone (CTX-30) and imipenem (IMP-10). The Isolated E. coli showed single or multi clade decadency. The E. coli and ARGs sequences showed single or multi clade decadency. This is first comprehensive study from Pakistan that described the molecular evidences of ARGs and their co-existence in single isolates originated from commercial poultry. Commercial chicken (Broilers) can act as melting pot of antibiotic resistance genes for human being. It is alarming situation for surveillance of antibiotic resistance program because of more regulated prescription of antimicrobial agents in Pakistan.
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Affiliation(s)
- W A Madni
- Government College University, Department of Microbiology, Faisalabad, Pakistan
| | - M Mohsin
- University of Agriculture, Institute of Microbiology, Faisalabad, Pakistan
| | - Z Nawaz
- Government College University, Department of Microbiology, Faisalabad, Pakistan
| | - S Muzammil
- Government College University, Department of Microbiology, Faisalabad, Pakistan
| | - M A Zahoor
- Government College University, Department of Microbiology, Faisalabad, Pakistan
| | - R Asif
- Qarshi University Lahore, Department of Eastern Medicine, Lahore, Pakistan
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Nawaz Z, Shafique M, Zahoor MA, Siddique AB, Ali S, Arshad R, Kausar S, Khan K, Asad M, Rehman AU, Masih I. Sero-epidemiology and risk factor analysis of human brucellosis in Punjab, Pakistan: a cross sectional study. Trop Biomed 2021; 38:413-419. [PMID: 34608115 DOI: 10.47665/tb.38.3.084] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Human brucellosis is a neglected zoonotic problem worldwide with a high degree of morbidity in humans and is mostly overlooked due to other febrile conditions. The aim of this study was to evaluate the sero-prevalence and risk factors of human brucellosis among subjects living in Punjab, Pakistan. In this cross-sectional study, human blood samples were collected from seven districts of Punjab, Pakistan. Information regarding personal data, demographic data and potential risk factors was collected through a structured questionnaire. Detection of anti-Brucella antibodies was done through Rose Bengal Plate Test (RBPT) and Enzyme Linked Immunosorbent Assay (ELISA). Descriptive analysis, Chi square test and Odds ratio was applied using STATA software version 12. The sero-prevalence of human brucellosis was 13.13% with significantly higher percentage in males 17.23% and age group 25-40 years 16.50% (P=< 0.001). The demographic factors positively associated with human brucellosis were lack of education (P = 0.003; OR = 1.85) and farming as an occupation (P =<0.001; OR = 2.50) Similarly, among the risk factors studied, keeping animals at home (P =<0.001; OR = 2.03), slaughtering of animals (P =<0.001; OR = 15.87) and consuming raw milk (P =<0.001; OR = 5.42) were the factors strongly connected with human brucellosis. A massive awareness should be given to livestock farmers and individuals directly linked to animals regarding risk factors and transmission of brucellosis. Consumption of unpasteurized milk and its products should be condemned to curtail this neglected disease.
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Affiliation(s)
- Z Nawaz
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
| | - M Shafique
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
| | - M A Zahoor
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
| | - A B Siddique
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
| | - S Ali
- Veterinary Research Institute, Lahore, Punjab, Pakistan
| | - R Arshad
- University College of Conventional Medicine, The Islamia University of Bahawalpur, Punjab, Pakistan
| | - S Kausar
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
| | - K Khan
- DHQ Hospital, Bhakkar, Punjab Pakistan
| | - M Asad
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
| | - A U Rehman
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
| | - I Masih
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
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Nawaz Z, Rasool MH, Siddique AB, Zahoor MA, Muzammil S, Shabbir MU, Javaid A, Chaudhry M. Prevalence and risk factors of Syphilis among blood donors of Punjab, Pakistan. Trop Biomed 2021; 38:106-110. [PMID: 33797532 DOI: 10.47665/tb.38.1.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Syphilis is a sexually transmitted disease and its actual prevalence among Pakistani blood donors is currently unknown. A cross sectional study was conducted at different district healthcare hospitals of Punjab, Pakistan with an aim to evaluate the prevalence and risk factors associated with syphilis in blood donors using immunochromatographic test (ICT) and enzyme linked immunosorbent assay (ELISA). A total (n=1200) blood samples were collected from donors aged 18-65 years. All the information regarding personal data, demographic data and risk factors was collected via structured questionnaire. On the basis of ICT and ELISA, the overall prevalence of syphilis was 3.91% among blood donors. The demographic factors positively linked with syphilis were age (P= 0.000; Odds ratio, OR= 7.18; 95% confidence interval CI= 2.816-18.295) and education status (P= 0.000; Odds ratio, OR= 12.33; 95% confidence interval CI= 3.469-43.849) of donors. Similarly among the risk factors analyzed, marital status (P= 0.012; Odds ratio OR= 2.251; 95% confidence interval CI= 1.206- 4.202) and blood transfusion history (P= 0.030; Odds ratio OR= 1.981; 95% confidence interval CI= 1.083-3.623) were also strongly associated with syphilis. We emphasized the importance of promoting preventive measures for syphilis. The syphilis diagnosis should not be based on a single test. The present study indicates that higher prevalence is alarming for blood donors in Pakistan. Stringent donor screening is highly recommended to ensure maximum safe blood transfusion.
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Affiliation(s)
- Z Nawaz
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
| | - M H Rasool
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
| | - A B Siddique
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
| | - M A Zahoor
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
| | - S Muzammil
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
| | - M U Shabbir
- Medical Laboratory Technician, DHQ Hospital, Mandi Bahauddin, Punjab, Pakistan
| | - A Javaid
- Department of Microbiology, Government College University Faisalabad, Punjab, Pakistan
| | - M Chaudhry
- Medical Laboratory Technician, DHQ Hospital, Okara, Punjab, Pakistan
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Narang A, Chan G, Aframian A, Ali Z, Carr A, Goodier H, Morgan C, Park C, Sugand K, Walton T, Wilson M, Belgaumkar A, Gallagher K, Ghosh K, Gibbons C, Keightley A, Nawaz Z, Wakeling C, Sarraf K, Rogers BA, Kieffer WKM. Thirty-day mortality following surgical management of hip fractures during the COVID-19 pandemic: findings from a prospective multi-centre UK study. Int Orthop 2021. [PMID: 32862265 DOI: 10.1007/s00264-020-04739-y/figures/2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
Abstract
PURPOSE Thirty-day mortality of patients with hip fracture is well researched and predictive; validated scoring tools have been developed (Nottingham Hip Fracture Score, NHFS). COVID-19 has significantly greater mortality in the elderly and comorbid patients which includes hip fracture patients. Non-operative treatment is not appropriate due to significantly higher mortality, and therefore, these patients are often exposed to COVID-19 in the peri-operative period. What is unclear is the effect of concomitant COVID-19 infection in these patients. METHODS A multicentre prospective study across ten sites in the United Kingdom (responsible for 7% of hip fracture patients per annum in the UK). Demographic and background information were collected by independent chart review. Data on surgical factors included American Society of Anesthesiologists (ASA) score, time to theatre, Nottingham Hip fracture score (NHFS) and classification of fracture were also collected between 1st March 2020 and 30th April 2020 with a matched cohort from the same period in 2019. RESULTS Actual and expected 30-day mortality was found to be significantly higher than expected for 2020 COVID-19 positive patients (RR 3.00 95% CI 1.57-5.75, p < 0.001), with 30 observed deaths compared against the 10 expected from NHFS risk stratification. CONCLUSION COVID-19 infection appears to be an independent risk factor for increased mortality in hip fracture patients. Whilst non-operative management of these fractures is not suggested due to the documented increased risks and mortality, this study provides evidence to the emerging literature of the severity of COVID-19 infection in surgical patients and the potential impact of COVID-19 on elective surgical patients in the peri-operative period.
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Affiliation(s)
- A Narang
- Surrey and Sussex Healthcare NHS Trust, East Surrey Hospital, Canada Avenue, Redhill, Surrey, RH1 5RH, UK
| | - G Chan
- Western Sussex Hospitals NHS Foundation Trust, Chichester, UK
| | - A Aframian
- Chelsea and Westminster Hospital NHS Foundation Trust, London, UK
| | - Z Ali
- Surrey and Sussex Healthcare NHS Trust, East Surrey Hospital, Canada Avenue, Redhill, Surrey, RH1 5RH, UK
| | - A Carr
- Surrey and Sussex Healthcare NHS Trust, East Surrey Hospital, Canada Avenue, Redhill, Surrey, RH1 5RH, UK
| | - H Goodier
- Poole General Hospital & the Royal Bournemouth Hospital, Poole, UK
| | - C Morgan
- Chelsea and Westminster Hospital NHS Foundation Trust, London, UK
| | - C Park
- St Mary's Hospital, London, London, UK
| | - K Sugand
- St Mary's Hospital, London, London, UK
| | - T Walton
- Brighton and Sussex University Hospitals, Brighton, UK
| | - M Wilson
- Poole General Hospital & the Royal Bournemouth Hospital, Poole, UK
| | - A Belgaumkar
- Surrey and Sussex Healthcare NHS Trust, East Surrey Hospital, Canada Avenue, Redhill, Surrey, RH1 5RH, UK
| | - K Gallagher
- Poole General Hospital & the Royal Bournemouth Hospital, Poole, UK
| | - K Ghosh
- Western Sussex Hospitals NHS Foundation Trust, Chichester, UK
| | - C Gibbons
- Chelsea and Westminster Hospital NHS Foundation Trust, London, UK
| | - A Keightley
- Royal Surrey Hospital NHS Foundation Trust, Guildford, UK
| | - Z Nawaz
- Frimley Park Hospital, Camberley, UK
| | - C Wakeling
- Western Sussex Hospitals NHS Foundation Trust, Chichester, UK
| | - K Sarraf
- St Mary's Hospital, London, London, UK
| | - B A Rogers
- Brighton and Sussex University Hospitals, Brighton, UK
| | - W K M Kieffer
- Surrey and Sussex Healthcare NHS Trust, East Surrey Hospital, Canada Avenue, Redhill, Surrey, RH1 5RH, UK.
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Guo Y, Li X, Zhao Z, Nawaz Z. Predicting the impacts of climate change, soils and vegetation types on the geographic distribution of Polyporus umbellatus in China. Sci Total Environ 2019; 648:1-11. [PMID: 30103037 DOI: 10.1016/j.scitotenv.2018.07.465] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 07/31/2018] [Accepted: 07/31/2018] [Indexed: 06/08/2023]
Abstract
Polyporus umbellatus is a fungus that has been used medically as a diuretic for thousands of years in China. To evaluate the impacts of climatic change on the distribution of P. umbellatus, we selected the annual mean air temperature, isothermality, minimum temperature of the coldest month, annual temperature range, annual precipitation and precipitation seasonality and used observations from the 2000s and simulated values from two future periods (2041 to 2060 and 2061 to 2080) to build an ensemble model (EM); then, we developed a comprehensive habitat suitability model by integrating soil and vegetation conditions into the EM to assess the distribution of suitable P. umbellatus habitats across China in the 2000s and the two future periods. Our results show that annual precipitation and annual mean air temperature together largely determine the distribution of P. umbellatus and those suitable P. umbellatus habitats generally occur in areas with an optimal annual precipitation of approximately 1000 mm and an optimal annual mean air temperature of approximately 13 °C. In other words, P. umbellatus requires a humid and cool environment for growth. In addition, brown soils with a granular structure and low acidity are more suitable for P. umbellatus. Furthermore, we have observed that the distribution of P. umbellatus is usually associated with the presence of coniferous, mixed coniferous, and broad-leaved forests, suggesting that these vegetation types are suitable habitats for P. umbellatus. In the future, annual precipitation and annual mean air temperature will continue to increase, consequently increasing the availability of habitats suitable for P. umbellatus in northeastern and southwestern China but likely leading to a degradation of suitable P. umbellatus habitats in central China.
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Affiliation(s)
- Yanlong Guo
- Northwest Institute of the Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of the Chinese Academy of Sciences, Beijing 100049, China.
| | - Xin Li
- University of the Chinese Academy of Sciences, Beijing 100049, China; Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China.
| | - Zefang Zhao
- College of Tourism and Environment, Shaanxi Normal University, Xian 710119, China.
| | - Zain Nawaz
- Northwest Institute of the Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of the Chinese Academy of Sciences, Beijing 100049, China.
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Kakar KU, Nawaz Z, Cui Z, Almoneafy AA, Ullah R, Shu QY. Rhizosphere-associated Alcaligenes and Bacillus strains that induce resistance against blast and sheath blight diseases, enhance plant growth and improve mineral content in rice. J Appl Microbiol 2018; 124:779-796. [PMID: 29280555 DOI: 10.1111/jam.13678] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 11/21/2017] [Accepted: 12/19/2017] [Indexed: 11/30/2022]
Abstract
AIMS To examine the biocontrol activities of five rhizobacterial strains (i.e. Alcaligenes faecalis strains Bk1 and P1, Bacillus amyloliquefaciens strain Bk7 and Brevibacillus laterosporus stains B4 and S5), to control the rice blast and sheath blight diseases in greenhouse and to study their possible modes of action. METHODS AND RESULTS Five potential plant growth-promoting rhizobacterial (PGPR) strains isolated from rice rhizospheres were tested for in vitro antifungal activities against Magnaporthe oryzae, Rhizoctonia solani, Botrytis cinerea and Fusarium graminearum. In vitro trials showed that three strains, Bk1, P1 and Bk7, were able to unanimously suppress the mycelial growth of the target pathogens. In greenhouse, the application of these three PGPR strains significantly suppressed the incidences of rice blast and sheath blight diseases. At 2 weeks after pathogen inoculation, the highest percentages of disease suppression were noted for Alc. faecalis strain Bk1 (72%) for rice blast, Alc. faecalis strain P1 (71%) for sheath blight, followed by B. amyloliquefaciens strain Bk7. Moreover, these strains significantly improved the plant growth, enriched the content of mineral nutrients in seedlings and increased the expression of major defence-related rice genes. All three strains were marked positive for phosphate solubilization, the production of indoleacetic acid, ammonia and siderophores and catalase activity. In addition, these strains were able to form biofilms and carried multiple lipopeptide biosynthetic genes as revealed by multiplex PCR. CONCLUSION This study reports new potential biocontrol agents for blast and sheath blight diseases of rice. SIGNIFICANCE AND IMPACT OF THE STUDY This study contributes to better understanding of the mechanisms involved in interaction between beneficial rhizobacteria, fungal pathogens and host plants.
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Affiliation(s)
- K U Kakar
- State Key Laboratory of Rice Biology, Institution of Crop Science, Zhejiang University, Hangzhou, China.,Molecular Genetics Key Laboratory of China Tobacco, Guizhou Academy of Tobacco Science, Guiyang, China
| | - Z Nawaz
- Molecular Genetics Key Laboratory of China Tobacco, Guizhou Academy of Tobacco Science, Guiyang, China
| | - Z Cui
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experimental Station, New Haven, CT, USA.,Department of Biological Sciences, University of Wisconsin, Milwaukee, WI, USA
| | - A A Almoneafy
- Department of Biological Sciences, College of Education and Science, Albaydaa University, Rada'a, Yemen
| | - R Ullah
- Department of Environmental Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Q-Y Shu
- State Key Laboratory of Rice Biology, Institution of Crop Science, Zhejiang University, Hangzhou, China
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Kakar KU, Ren XL, Nawaz Z, Cui ZQ, Li B, Xie GL, Hassan MA, Ali E, Sun GC. A consortium of rhizobacterial strains and biochemical growth elicitors improve cold and drought stress tolerance in rice (Oryza sativa L.). Plant Biol (Stuttg) 2016; 18:471-83. [PMID: 26681628 DOI: 10.1111/plb.12427] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 12/11/2015] [Indexed: 05/20/2023]
Abstract
In the present study, a consortium of two rhizobacteria Bacillus amyloliquefaciens Bk7 and Brevibacillus laterosporus B4, termed 'BB', biochemical elicitors salicylic acid and β-aminobutyric acid (SB) and their mixture (BBSB) were investigated for cold and drought stress tolerance in rice plants. After withholding water for 16 days, rice plants treated with BBSB showed 100% survival, improved seedling height (35.4 cm), shoot number (6.12), and showed minimum symptoms of chlorosis (19%), wilting (4%), necrosis (6%) and rolling of leaves. Similarly, BB inoculation enhanced plant growth and reduced overall symptoms in rice seedlings subjected to 0 ± 5 °C for 24 h. Our results imply several mechanisms underlying BB- and BBSB-elicited stress tolerance. In contrast to the control, both treatments significantly decreased leaf monodehydroascorbate (MDA) content and electrolyte leakage, and increased leaf proline and cholorophyll content. Moreover, activities of antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT) increased 3.0- and 3.6-fold, respectively. Moreover, expression of OsMYB3R-2, OsDIL, OsDREB1A and OsCDPK13 genes was significantly up-regulated, suggesting that these genes play important roles in abiotic stress tolerance of rice. In addition, bacterial strains Bk7 and B4 were able to produce high amounts of IAA and siderophores, and colonise the plant roots, while only strain Bk7 exhibited the capability to form biofilms and solubilise inorganic phosphate. This study indicates that the BB and BBSB bio-formulations can be used to confer induced systematic tolerance and improve the health of rice plants subject to chilling and drought stress.
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Affiliation(s)
- K U Kakar
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China
- Guizhou Academy of Tobacco Science, Guiyang, China
| | - X-L Ren
- Guizhou Academy of Tobacco Science, Guiyang, China
| | - Z Nawaz
- Guizhou Academy of Tobacco Science, Guiyang, China
| | - Z-Q Cui
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China
| | - B Li
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China
| | - G-L Xie
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China
| | - M A Hassan
- University of Maiduguri, Maiduguri, Nigeria
| | - E Ali
- College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China
| | - G-C Sun
- State Key Laboratory Breeding Base for Zhejiang Sustainable Plant Pest and Disease Control, Key Laboratory of Detection for Pesticide Residues, Ministry of Agriculture, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
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Bener A, Zirie M, Al-Hamaq AOAA, Nawaz Z, Samson N, Mohammad R. Impact of the Pro12Ala polymorphism of the PPARγ2 gene on diabetes and obesity in a highly consanguineous population. Indian J Endocrinol Metab 2015; 19:77-83. [PMID: 25593831 PMCID: PMC4287785 DOI: 10.4103/2230-8210.131766] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND The peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor subfamily of transcription factors. It has been reported that they play important roles in obesity and the development of type 2 diabetes mellitus (T2DM). MATERIALS AND METHODS This case-control study was carried out among 764 Qatari patients with diabetes and 764 healthy subjects above 20 years of age at Primary Healthcare Clinics (PHCs) from January 2011 to December 2012. Face-to-face interviews were based on a questionnaire that included variables such as age, sex, sociodemographic status, body mass index (BMI) and other clinical parameters. The Pro12Ala in the PPARγ2 gene was detected on the LightCycler using two specific probes. Univariate and multivariate statistical analysis were performed. RESULTS The study revealed that in the diabetes group, Pro/(10.2% vs 9.4%; P = 0.606) and Ala/Ala (1.4% vs 0.9%; P = 0.343) were higher than in controls, whereas Pro/Pro (88.4% vs 89.7%;P = 0.413) was lower in diabetes patients, but no significant difference was observed among the genotype groups. In obese patients with diabetes, Pro/Pro (89% vs 89.9%;P = 0.792) and Pro/Ala (8.9% vs 10.1%;P = 0.671) were lower than in obese healthy subjects. No homozygous Ala/Ala was found in obese healthy subjects, whereas 6 Ala/Ala homozygotes were in obese diabetes group. But in diabetes group, obese patients had higher homozygous of Pro/Pro (89.3% vs 87.8%;P = 0.523) and Ala/Ala (1.8% vs 1.2%;P = 0.771) compared to non-obese patients. CONCLUSION The current study did not reveal an association between the Pro12Ala polymorphism of the PPAR γ2 gene and type 2 diabetes (T2D) in Qatari's population.
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Affiliation(s)
- Abdulbari Bener
- Department of Medical Statistics and Epidemiology, Hamad Medical Corporation, Doha, Qatar
- Department of Evidence for Population Health Unit, School of Epidemiology and Health Sciences, The University of Manchester, Manchester, UK
| | - M Zirie
- Department of Endocrinology, Hamad Medical Corporation, Hamad General Hospital, Qatar
| | - AOAA Al-Hamaq
- Qatar Diabetic Association and Qatar Foundation, Doha, Qatar
| | - Z Nawaz
- Department of Laboratory Medicine and Pathology, Cytogenetics and Molecular Cytogenetics Laboratory, Hamad Medical Corporation, Qatar
| | - N Samson
- Department of Medical Statistics and Epidemiology, Hamad Medical Corporation, Doha, Qatar
| | - R Mohammad
- Department of Oncology, Wayne State University, School of medicine, Michigan, USA, and Department of Medicine, Hamad Medical Corporation, State of Qatar
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10
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Nawaz Z, Mushtaq F, Mousa D, Rehman E, Sulaiman M, Aslam N, Khawaja N. Pattern of glomerular disease in the Saudi population: a single-center, five-year retrospective study. Saudi J Kidney Dis Transpl 2014; 24:1265-70. [PMID: 24231502 DOI: 10.4103/1319-2442.121288] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Glomerular diseases continue to be the leading cause of end-stage renal disease (ESRD) globally. Hence, it is important to recognize the pattern of glomerular diseases in different geographical areas in order to understand the patho-biology, incidence and progression of the disorder. Published studies from different centers in Saudi Arabia have reported contradicting results. In this retrospective study, we report our experience at the Armed Forces Hospital, Riyadh, Saudi Arabia. A total of 348 native renal biopsies performed at our center on patients with proteinuria >1 g, hematuria and/or renal impairment during a period of 5 years (between January 2005 and December 2009) were studied by a histopathologist using light microscopy, immunofluorescence and electron microscopy, and were categorized. Results showed that primary glomerular disease accounted for 55.1% of all renal biopsies. The most common histological lesion was focal and segmental glomerulosclerosis (FSGS) (27.6%), followed by minimal change disease (MCD) (17.7%) and membrano-proliferative glomerulonephritis (MPGN) (13.0%). Secondary glomerular disease accounted for 37.9% of the glomerular diseases, with lupus nephritis (LN) being the most common lesion (54.5%), followed by hypertensive nephrosclerosis (22%), post-infectious glomerulonephritis (7.5%), diabetic nephropathy (DN) (6.8%) and vasculitides (4.5%). Four percent of all biopsies turned out to be ESRD while biopsy was inadequate in 2.8% of the cases. In conclusion, our study showed that FSGS was the most common primary GN encountered, while LN was the most common secondary GN. We encountered 14 cases of crescentic glomerulonephritis. Also, the prevalence of MPGN, MCD, IgA nephropathy and membranous GN was many folds higher in males when compared with the Western data. We believe that it is mandatory to maintain a Saudi Arabian Renal Biopsy Registry to understand better the pattern of glomerular disease in the Saudi population and to follow any change in trend.
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Affiliation(s)
- Z Nawaz
- Department of Nephrology, Armed Forces Hospital, Riyadh, Saudi Arabia
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11
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Fahiminiya S, Almuriekhi M, Nawaz Z, Staffa A, Lepage P, Ali R, Hashim L, Schwartzentruber J, Abu Khadija K, Zaineddin S, Gamal H, Majewski J, Ben-Omran T. Whole exome sequencing unravels disease-causing genes in consanguineous families in Qatar. Clin Genet 2013; 86:134-41. [PMID: 24102521 DOI: 10.1111/cge.12280] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 08/16/2013] [Accepted: 09/12/2013] [Indexed: 01/02/2023]
Abstract
Whole exome sequencing (WES) has greatly facilitated the identification of causal mutations for diverse human genetic disorders. We applied WES as a molecular diagnostic tool to identify disease-causing genes in consanguineous families in Qatar. Seventeen consanguineous families with diverse disorders were recruited. Initial mutation screening of known genes related to the clinical diagnoses did not reveal the causative mutations. Using WES approach, we identified the definitive disease-causing mutations in four families: (i) a novel nonsense homozygous (c.1034C>G) in PHKG2 causing glycogen storage disease type 9C (GSD9C) in a male with initial diagnosis of GSD3; (ii) a novel homozygous 1-bp deletion (c.915del) in NSUN2 in a male proband with Noonan-like syndrome; (iii) a homozygous SNV (c.1598C>G) in exon 11 of IDUA causing Hurler syndrome in a female proband with unknown clinical diagnosis; (iv) a de novo known splicing mutation (c.1645+1G>A) in PHEX in a female proband with initial diagnosis of autosomal recessive hypophosphatemic rickets. Applying WES as a diagnostic tool led to the unambiguous identification of disease-causing mutations in phenotypically complex disorders or correction of the initial clinical diagnosis in ˜25% of our cases.
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Affiliation(s)
- S Fahiminiya
- Department of Human Genetics, Faculty of Medicine, McGill University and Genome Quebec Innovation Center, Montreal, Quebec, Canada
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12
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Matthies A, Underwood R, Cann P, Ilo K, Nawaz Z, Skinner J, Hart AJ. Retrieval analysis of 240 metal-on-metal hip components, comparing modular total hip replacement with hip resurfacing. ACTA ACUST UNITED AC 2011; 93:307-14. [DOI: 10.1302/0301-620x.93b3.25551] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This study compared component wear rates and pre-revision blood metal ions levels in two groups of failed metal-on-metal hip arthroplasties: hip resurfacing and modular total hip replacement (THR). There was no significant difference in the median rate of linear wear between the groups for both acetabular (p = 0.4633) and femoral (p = 0.0872) components. There was also no significant difference in the median linear wear rates when failed hip resurfacing and modular THR hips of the same type (ASR and Birmingham hip resurfacing (BHR)) were compared. Unlike other studies of well-functioning hips, there was no significant difference in pre-revision blood metal ion levels between hip resurfacing and modular THR. Edge loading was common in both groups, but more common in the resurfacing group (67%) than in the modular group (57%). However, this was not significant (p = 0.3479). We attribute this difference to retention of the neck in resurfacing of the hip, leading to impingement-type edge loading. This was supported by visual evidence of impingement on the femur. These findings show that failed metal-on-metal hip resurfacing and modular THRs have similar component wear rates and are both associated with raised pre-revision blood levels of metal ions.
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Affiliation(s)
| | | | - P. Cann
- Department of Mechanical Engineering
| | - K. Ilo
- Department of Musculoskeletal Surgery
| | - Z. Nawaz
- Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex HA7 4LP, UK
| | - J. Skinner
- Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex HA7 4LP, UK
| | - A. J. Hart
- Department of Orthopaedic Surgery, Imperial College London (Charing Cross Hospital Campus), Fulham Palace Road, London W6 8RF, UK
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13
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Nawaz Z, Tang X, Wei F. Hexene catalytic cracking over 30% sapo-34 catalyst for propylene maximization: influence of reaction conditions and reaction pathway exploration. Braz J Chem Eng 2009. [DOI: 10.1590/s0104-66322009000400009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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14
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Nawaz Z, Shu Q, Naveed S, Wei F. Light alkane (mixed feed) selective dehydrogenation using bi-metallic zeolite supported catalyst. B CHEM SOC ETHIOPIA 2009. [DOI: 10.4314/bcse.v23i3.47667] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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15
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Moore SJ, Buckley DJ, MacMillan A, Marshall HD, Steele L, Ray PN, Nawaz Z, Baskin B, Frecker M, Carr SM, Ives E, Parfrey PS. The clinical and genetic epidemiology of neuronal ceroid lipofuscinosis in Newfoundland. Clin Genet 2008; 74:213-22. [PMID: 18684116 DOI: 10.1111/j.1399-0004.2008.01054.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The neuronal ceroid lipofuscinoses (NCLs) are the commonest neurodegenerative disorders of children. The aims of this study were to determine the incidence of NCL in Newfoundland, identify the causative genes, and analyze the relationship between phenotype and genotype. Patients with NCL diagnosed between 1960 and 2005 were ascertained through the provincial genetics and pediatric neurology clinics. Fifty-two patients from 34 families were identified. DNA was obtained from 28/34 (82%) families; 18 families had mutations in the CLN2 gene, comprising five different mutations of which two were novel. One family had a CLN3 mutation, another had a novel mutation in CLN5, and five families shared the same mutation in CLN6. One family was misdiagnosed, and in two, molecular testing was inconclusive. Disease from CLN2 mutations had an earlier presentation (p = 0.003) and seizure onset (p < 0.001) compared with CLN6 mutation. There was a slower clinical course for those with CLN5 mutation compared with CLN2 mutation. NCL in Newfoundland has a high incidence, 1 in 7353 live births, and shows extensive genetic heterogeneity. The incidence of late infantile NCL, 9.0 per 100,000 (or 1 in 11,161) live births, is the highest reported in the world.
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Affiliation(s)
- S J Moore
- Department of Pediatrics, Memorial University of Newfoundland, St John's, Newfoundland, Canada.
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16
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Burjonrappa SC, Reddimasu S, Nawaz Z, Gao X, Sharma P, Loggie B. Mucin expression profile in Barrett's, dysplasia, adenocarcinoma sequence in the esophagus. Indian J Cancer 2007; 44:1-5. [PMID: 17401217 DOI: 10.4103/0019-509x.31160] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND The molecular events that accompany the progression to adenocarcinoma (ADC) of the esophagus are poorly understood. Aberrant mucin receptor expression can contribute to increased cell growth and metastatic ability. AIM The aim of this study was to establish a pattern for mucin (MUC) gene expression in the esophageal mucosa under normal and pathological conditions. SETTING University Hospital Cancer Center Laboratory. Archived tissue samples studied in a retrospective fashion. MATERIALS AND METHODS Tissue samples were obtained from the archives of patients with histological evidence of Barrett's esophagus (BE) progressing to ADC. Immunohistochemical analysis was performed using mouse monoclonal antibodies for MUC1, MUC2, MUC5AC, MUC6. Semiquantitative scoring of histological staining was performed using a linear scoring system: 0-staining absent; 1-staining in 0-25%; 2-staining in 25-50%; and 3-staining in 50-75% of the epithelium. The Binomial test was used to explore trends and differences in frequency of mucin expression along the pathological sequence. RESULTS Only mild superficial staining of MUC1 was seen in normal squamous epithelium. MUC1 and MUC2 were uniformly expressed in all samples (7/7) of BE and dysplasia (P=0.008). MUC1 expression was upregulated (7/7) in progression to adenocarcinoma (P=0.008). The secretory mucins, MUC5AC and MUC6 showed a decrease in expression with progression from BE to dysplasia to ADC (P< 0.05). CONCLUSIONS Downregulation of MUC5AC and MUC6 decreases mucosal protection against gastric acid. Increasing MUC1 expression is associated with progression from dysplasia to ADC. Upregulation of MUC2 reflects intestinal metaplasia in BE.
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Affiliation(s)
- S C Burjonrappa
- Department of Surgical Oncology, Creighton University, Omaha, NE 68131, USA.
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17
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Silva E, Loggie BW, Nawaz Z, Gatalica Z, El-Ella GA. Inhibition of mucin 2 production: Implications for treatment of pseudomyxoma peritonei. Ann Surg Oncol 2004. [DOI: 10.1007/bf02524018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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18
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Abstract
Nuclear hormone receptors (NHRs) represent a superfamily of structurally related ligand-activated transcription factors, which regulate diverse biological activities like growth, development, and homeostasis. Recently, it has been demonstrated that certain members of the NHR superfamily are degraded through the ubiquitin-proteasome pathway in a ligand-dependent manner. Though the signal for the down-regulation via the ubiquitin-proteasome pathway is not yet known, phosphorylation at specific amino acid residues or coactivator binding to receptors could lead to their degradation by the 26S proteasome. Activation and degradation seems to be an engineered cyclic mechanism, which provides tight control over diverse cellular processes. The degradation process involves extensive loss of proteins and requires expenditure of cellular ATP. That seems to be inevitable for a more important aim, that is efficient and appropriate regulation of transcription. Down-regulation of receptors would lead to an attenuated transcriptional response because the number of receptor molecules available to activate transcription would decrease over time. One of the obvious reasons for down-regulating NHRs thus seems to be to prevent the cell from overstimulation by the hormones or other activating signals. Nuclear receptor turnover may also reset the transcriptional apparatus in preparation for a subsequent response. Since inhibition of the ubiquitin-proteasome degradation pathway disturbs the transcriptional activitity of some of the nuclear receptors such as estrogen (ER) and progesterone (PR) receptors, it is also possible that the degradation of NHRs may enable recycling of components of receptor-cofactor complexes and general transcriptional machinary. Understanding the mechanism of nuclear hormone receptor degradation and its relation to transcription may lead to novel insights of therapuetic intervention.
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Affiliation(s)
- A P Dennis
- Baylor College of Medicine, Houston, TX 77030, USA
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19
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Zhao HH, Herrera RE, Coronado-Heinsohn E, Yang MC, Ludes-Meyers JH, Seybold-Tilson KJ, Nawaz Z, Yee D, Barr FG, Diab SG, Brown PH, Fuqua SA, Osborne CK. Forkhead homologue in rhabdomyosarcoma functions as a bifunctional nuclear receptor-interacting protein with both coactivator and corepressor functions. J Biol Chem 2001; 276:27907-12. [PMID: 11353774 DOI: 10.1074/jbc.m104278200] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In a search for novel transcriptional intermediary factors for the estrogen receptor (ER), we used the ligand-binding domain and hinge region of ER as bait in a yeast two-hybrid screen of a cDNA library derived from tamoxifen-resistant MCF-7 human breast tumors from an in vivo athymic nude mouse model. Here we report the isolation and characterization of the forkhead homologue in rhabdomyosarcoma (FKHR), a recently described member of the hepatocyte nuclear factor 3/forkhead homeotic gene family, as a nuclear hormone receptor (NR) intermediary protein. FKHR interacts with both steroid and nonsteroid NRs, although the effect of ligand on this interaction varies by receptor type. The interaction of FKHR with ER is enhanced by estrogen, whereas its interaction with thyroid hormone receptor and retinoic acid receptor is ligand-independent. In addition, FKHR differentially regulates the transactivation mediated by different NRs. Transient transfection of FKHR into mammalian cells dramatically represses transcription mediated by the ER, glucocorticoid receptor, and progesterone receptor. In contrast, FKHR stimulates rather than represses retinoic acid receptor- and thyroid hormone receptor-mediated transactivation. Most intriguingly, overexpression of FKHR dramatically inhibits the proliferation of ER-dependent MCF-7 breast cancer cells. Therefore, FKHR represents a bifunctional NR intermediary protein that can act as either a coactivator or corepressor, depending on the receptor type.
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Affiliation(s)
- H H Zhao
- Division of Oncology, Department of Medicine, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, Texas 78284, USA
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20
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Hyder SM, Huang JC, Nawaz Z, Boettger-Tong H, Mäkelä S, Chiappetta C, Stancel GM. Regulation of vascular endothelial growth factor expression by estrogens and progestins. Environ Health Perspect 2000; 108 Suppl 5:785-790. [PMID: 11035983 DOI: 10.1289/ehp.00108s5785] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Estrogens increase the expression of vascular endothelial growth factor (VEGF) mRNA in the rodent uterus. This regulatory effect is rapid, beginning within 1 hr after hormone treatment, dose dependent, and blocked by the pure antiestrogen ICI 182,780. The induction of the transcript is blocked by inhibitors of RNA but not of protein synthesis, and we have recently identified estrogen response elements in the VEGF gene. Collectively, these findings indicate that estrogens regulate uterine VEGF expression at the transcriptional level via the classical nuclear estrogen receptor pathway. Estrogen induction of VEGF occurs in the stromal layer of the rodent uterus, and estradiol induces expression of VEGF transcript levels in cultured human uterine stromal cells. Progestins also induce VEGF expression in the rodent uterus, although the effect is less marked and slower in onset than estrogenic effects. The effect of progestins is blocked by the antiprogestin mifepristone (RU-486), suggesting that it is also mediated by a classical nuclear receptor pathway. In addition, progestins regulate expression of VEGF mRNA and protein in cultured human T47-D breast cancer cells. The development of uterine leiomyomas is associated with exposure to ovarian sex steroids, abnormal uterine bleeding is commonly seen in patients with leiomyomas, and fibroids require an increased vascular supply for their growth. These observations suggest that VEGF and other angiogenic factors may represent potential targets for the treatment and prevention of uterine fibroids.
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Affiliation(s)
- S M Hyder
- Department of Integrative Biology and Pharmacology, University of Texas-Houston Medical School, Houston, Texas 77225, USA.
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21
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Li J, Wang J, Wang J, Nawaz Z, Liu JM, Qin J, Wong J. Both corepressor proteins SMRT and N-CoR exist in large protein complexes containing HDAC3. EMBO J 2000; 19:4342-50. [PMID: 10944117 PMCID: PMC302030 DOI: 10.1093/emboj/19.16.4342] [Citation(s) in RCA: 487] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2000] [Revised: 06/21/2000] [Accepted: 06/26/2000] [Indexed: 11/13/2022] Open
Abstract
We present evidence that both corepressors SMRT and N-CoR exist in large protein complexes with estimated sizes of 1.5-2 MDa in HeLa nuclear extracts. Using a combination of conventional and immunoaffinity chromatography, we have successfully isolated a SMRT complex and identified histone deacetylase 3 (HDAC3) and transducin (beta)-like I (TBL1), a WD-40 repeat-containing protein, as the subunits of the purified SMRT complex. We show that the HDAC3-containing SMRT and N-CoR complexes can bind to unliganded thyroid hormone receptors (TRs) in vitro. We demonstrate further that in Xenopus oocytes, both SMRT and N-CoR also associate with HDAC3 in large protein complexes and that injection of antibodies against HDAC3 or SMRT/N-CoR led to a partial relief of repression by unliganded TR/RXR. These findings thus establish both SMRT and N-CoR complexes as bona fide HDAC-containing complexes and shed new light on the molecular pathways by which N-CoR and SMRT function in transcriptional repression.
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Affiliation(s)
- J Li
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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22
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Sivaraman L, Nawaz Z, Medina D, Conneely OM, O'Malley BW. The dual function steroid receptor coactivator/ubiquitin protein-ligase integrator E6-AP is overexpressed in mouse mammary tumorigenesis. Breast Cancer Res Treat 2000; 62:185-95. [PMID: 11072783 DOI: 10.1023/a:1006410111706] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Steroid receptor coactivator and corepressor proteins are important mediators of steroid receptor function. Changes in the expression or activity of these limiting cofactors can contribute to the etiology of steroidal cancers. Using a mouse mammary model of multistage tumorigenesis we have examined whether the expression of select steroid receptor coactivators is altered. The 10 kb transcript of the novel dual function steroid receptor coactivator/ubiquitin protein-ligase integrator E6-AP is overexpressed 2.5-4.5 fold in the mammary tumors but not in the precursor steps of tumorigenesis; that is, immortal ductal and alveolar hyperplastic outgrowths. The over expression is striking because the 10 kb transcript is expressed to variable levels in other wild type tissues like the uterus, ovary, testis, kidney and brain but is undetectable in normal virgin mammary gland and the prostate gland. The E6-AP overexpression in the mammary tumors is substantiated by western blot analysis and immunohistochemical analysis. Absence of ER and PR in these tumors in the presence of high levels of E6-AP could contribute to steroid receptor-independent function and tumorigenesis. There is no obvious correlation between p53 (a well-characterized substrate of E6-AP) status (wt vs. mutant) and levels of E6-AP in the mouse mammary tumors.
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Affiliation(s)
- L Sivaraman
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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23
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Hyder SM, Nawaz Z, Chiappetta C, Stancel GM. Identification of functional estrogen response elements in the gene coding for the potent angiogenic factor vascular endothelial growth factor. Cancer Res 2000; 60:3183-90. [PMID: 10866309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Vascular endothelial growth factor (VEGF) is a potent stimulator of angiogenesis and a prognostic factor for many tumors including those of endocrine-responsive tissues such as the breast and uterus. We and others have previously shown that VEGF is regulated by estradiol and tamoxifen in the uterus and by estradiol in human breast cancer cells, and pharmacological evidence has suggested that this regulation was mediated by transcriptional activation of the estrogen receptor (ER). This prompted us to investigate whether the VEGF gene contains sequences that bind the ER and confer hormonal inducibility to reporter constructs in the presence of the two ER subtypes. These studies identified two sequences homologous to the consensus estrogen response element, GGTCAnnnTGACC, which bind both ER-alpha and ER-beta. One of these elements is located in the 5'-untranslated region of the VEGF gene (GGGCAaagTGACT), and the other is located in the 3'-untranslated region (GAGCAcccTGCCC). Competition with excess unlabeled oligonucleotides indicates that these two elements bind both ERs specifically, mutations in either half-site of the two elements abolish receptor binding, and ER-alpha- and ER-beta-specific antibodies interact with complexes formed with the corresponding receptor subtypes. In cells containing either ER-alpha or ER-beta, the 3'-element behaves as a traditional enhancer that confers hormone inducibility to reporter constructs in an orientation-independent manner, and transcriptional activity is blocked by the pure antiestrogen ICI 182,780. The pattern of transcriptional activity of the element located in the 5'-flanking region is more complex. In the orientation found in the endogenous gene, this element is nonresponsive to ER-beta but confers estrogen-dependent inhibition of transcription with ER-alpha that is blunted by ICI 182,780. In the opposite orientation, the 5'-element confers hormone inducibility with either ER-alpha or -beta, and ICI 182,780 blocks activation by ER-alpha but not by ER-beta. These findings support the hypotheses that estrogens directly regulate VEGF transcription in target tissues and tumors, although such regulation appears likely to involve a complex interplay of cis- and trans-acting elements not previously observed for other hormone-responsive genes.
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Affiliation(s)
- S M Hyder
- Department of Integrative Biology and Pharmacology, University of Texas Health Sciences Center, Houston 77030, USA.
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24
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Lonard DM, Nawaz Z, Smith CL, O'Malley BW. The 26S proteasome is required for estrogen receptor-alpha and coactivator turnover and for efficient estrogen receptor-alpha transactivation. Mol Cell 2000; 5:939-48. [PMID: 10911988 DOI: 10.1016/s1097-2765(00)80259-2] [Citation(s) in RCA: 433] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Estrogen receptor-alpha (ER alpha) is downregulated in the presence of its cognate ligand, estradiol (E2), through the ubiquitin proteasome pathway. Here, we show that ubiquitin proteasome function is required for ER alpha to serve as a transcriptional activator. Deletion of the last 61 amino acids of ER alpha, including residues that form helix 12, abolishes ligand-mediated downregulation of the receptor as do point mutations in the ligand binding domain that impair coactivator binding. In addition, coactivators also are subject to degradation by the 26S proteasome, but their intrinsic transcriptional activity is not affected. These data provide evidence that protein interactions with ER alpha coactivator binding surfaces are important for ligand-mediated receptor down-regulation and suggest that receptor and coactivator turnover contributes to ER alpha transcriptional activity.
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Affiliation(s)
- D M Lonard
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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Shah BH, Nawaz Z, Pertani SA, Roomi A, Mahmood H, Saeed SA, Gilani AH. Inhibitory effect of curcumin, a food spice from turmeric, on platelet-activating factor- and arachidonic acid-mediated platelet aggregation through inhibition of thromboxane formation and Ca2+ signaling. Biochem Pharmacol 1999; 58:1167-72. [PMID: 10484074 DOI: 10.1016/s0006-2952(99)00206-3] [Citation(s) in RCA: 145] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Curcumin, a dietary spice from turmeric, is known to be anti-inflammatory, anticarcinogenic, and antithrombotic. Here, we studied the mechanism of the antiplatelet action of curcumin. We show that curcumin inhibited platelet aggregation mediated by the platelet agonists epinephrine (200 microM), ADP (4 microM), platelet-activating factor (PAF; 800 nM), collagen (20 microg/mL), and arachidonic acid (AA: 0.75 mM). Curcumin preferentially inhibited PAF- and AA-induced aggregation (IC50; 25-20 microM), whereas much higher concentrations of curcumin were required to inhibit aggregation induced by other platelet agonists. Pretreatment of platelets with curcumin resulted in inhibition of platelet aggregation induced by calcium ionophore A-23187 (IC50; 100 microM), but curcumin up to 250 microM had no inhibitory effect on aggregation induced by the protein kinase C (PKC) activator phorbol myrsitate acetate (1 microM). Curcumin (100 microM) inhibited the A-23187-induced mobilization of intracellular Ca2+ as determined by using fura-2 acetoxymethyl ester. Curcumin also inhibited the formation of thromboxane A2 (TXA2) by platelets (IC50; 70 microM). These results suggest that the curcumin-mediated preferential inhibition of PAF- and AA-induced platelet aggregation involves inhibitory effects on TXA2 synthesis and Ca2+ signaling, but without the involvement of PKC.
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Affiliation(s)
- B H Shah
- Department of Physiology and Pharmacology, The Aga Khan University, Karachi, Pakistan.
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26
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Robinson CE, Wu X, Nawaz Z, Onãte SA, Gimble JM. A corepressor and chicken ovalbumin upstream promoter transcriptional factor proteins modulate peroxisome proliferator-activated receptor-gamma2/retinoid X receptor alpha-activated transcription from the murine lipoprotein lipase promoter. Endocrinology 1999; 140:1586-93. [PMID: 10098492 DOI: 10.1210/endo.140.4.6653] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Complex physiological stimuli differentially regulate the tissue-specific transcription of the lipoprotein lipase (LPL) gene. A conserved DNA recognition element (-171 to -149 bp) within the promoter functions as a transcriptional enhancer when bound by the peroxisome proliferator-activated receptor-gamma2 (PPARgamma2)/retinoid X receptor alpha (RXRalpha) heterodimer, but serves as a transcriptional silencer in the presence of unidentified double and single stranded DNA-binding proteins. To address this apparent paradox, the current study examined the effect of two classes of candidate comodulatory proteins, COUP-TF (chicken ovalbumin upstream promoter transcriptional factor) and the corepressor SMRT (silencing mediator of retinoic acid receptor and thyroid receptor). The expression of COUP-TF was detected by Western and Northern blots in a preadipocyte 3T3-L1 cell model during periods corresponding to increased LPL transcription. Cotransfection of COUP-TF expression constructs in the renal epithelial 293T cell line significantly increased transcription from the LPL promoter in synergy with PPARgamma2/RXRalpha heterodimers. The COUP-TFII (ARP-1) protein specifically bound the LPL PPAR recognition element inelectromobility shift assays and interacted directly with the ligand-binding domain of PPARgamma in pull-down experiments. In contrast, cotransfection of SMRT repressed PPARgamma2/ RXRalpha-mediated LPL transcription in the absence or presence of COUP-TFII (ARP-1). The interaction between PPARgamma2 and SMRT localized to the receptor-interactive domain 2 (amino acids 1260-1495) of the SMRT protein based on cotransfection and pull-down assays. These in vitro data indicate that COUP-TF proteins and SMRT modulate PPARgamma-mediated LPL transcription in the 293T cell line.
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Affiliation(s)
- C E Robinson
- Zoology Department, University of Oklahoma, Norman 73019, USA
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Abstract
Nuclear receptors are ligand-inducible transcription factors which mediate the physiological effects of steroid, thyroid and retinoid hormones. By regulating the assembly of a transcriptional preinitiation complex at the promoter of target genes, they enhance the expression of these genes in response to hormone. Recent evidence suggests that nuclear receptors act in part by recruiting multiple coregulator proteins which may have specific functions during transcriptional initiation. Liganded receptors recruit members of the SRC family, a group of structurally and functionally related transcriptional coactivators. Receptors also interact with the transcriptional cointegrators p300 and CBP, which are proposed to integrate diverse afferent signals at hormone-regulated promoters. p300/CBP and members of the SRC coactivator family have intrinsic histone acetyltransferase activity which is believed to disrupt the nucleosomal structure at these promoters. Other nuclear receptor coactivators include a member of the SWI/SNF complex, BRG-1, which couples ATP hydrolysis to chromatin remodelling, and the E3 ubiquitin-protein ligases E6-AP and RPF-1. Finally, nuclear receptor coactivators appear to be organized into preformed subcomplexes, an arrangement that may facilitate their efficient assembly into diverse higher order configurations.
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Affiliation(s)
- N J McKenna
- Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030, USA
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Abstract
In eukaryotic cells, the ubiquitin-proteasome pathway is the major mechanism for the targeted degradation of proteins with short half-lives. The covalent attachment of ubiquitin to lysine residues of targeted proteins is a signal for the recognition and rapid degradation by the proteasome, a large multi-subunit protease. In this report, we demonstrate that the human estrogen receptor (ER) protein is rapidly degraded in mammalian cells in an estradiol-dependent manner. The treatment of mammalian cells with the proteasome inhibitor MG132 inhibits activity of the proteasome and blocks ER degradation, suggesting that ER protein is turned over through the ubiquitin-proteasome pathway. In addition, we show that in vitro ER degradation depends on ubiquitin-activating E1 enzyme (UBA) and ubiquitin-conjugating E2 enzymes (UBCs), and the proteasome inhibitors MG132 and lactacystin block ER protein degradation in vitro. Furthermore, the UBA/UBCs and proteasome inhibitors promote the accumulation of higher molecular weight forms of ER. The UBA and UBCs, which promote ER degradation in vitro, have no significant effect on human progesterone receptor and human thyroid hormone receptor beta proteins.
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Affiliation(s)
- Z Nawaz
- Department of Cell Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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Nawaz Z, Lonard DM, Smith CL, Lev-Lehman E, Tsai SY, Tsai MJ, O'Malley BW. The Angelman syndrome-associated protein, E6-AP, is a coactivator for the nuclear hormone receptor superfamily. Mol Cell Biol 1999; 19:1182-9. [PMID: 9891052 PMCID: PMC116047 DOI: 10.1128/mcb.19.2.1182] [Citation(s) in RCA: 321] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/1998] [Accepted: 10/27/1998] [Indexed: 12/16/2022] Open
Abstract
In this study, we found that the E6-associated protein (E6-AP/UBE3A) directly interacts with and coactivates the transcriptional activity of the human progesterone receptor (PR) in a hormone-dependent manner. E6-AP also coactivates the hormone-dependent transcriptional activities of the other members of the nuclear hormone receptor superfamily. Previously, it was shown that E6-AP serves the role of a ubiquitin-protein ligase (E3) in the presence of the E6 protein from human papillomavirus types 16 and 18. Our data show that the ubiquitin-protein ligase function of E6-AP is dispensable for its ability to coactivate nuclear hormone receptors, showing that E6-AP possesses two separable independent functions, as both a coactivator and a ubiquitin-protein ligase. Disruption of the maternal copy of E6-AP is correlated with Angelman syndrome (AS), a genetic neurological disorder characterized by severe mental retardation, seizures, speech impairment, and other symptoms. However, the exact mechanism by which the defective E6-AP gene causes AS remains unknown. To correlate the E6-AP coactivator function and ubiquitin-protein ligase functions with the AS phenotype, we expressed mutant forms of E6-AP isolated from AS patients and assessed the ability of each of these mutant proteins to coactivate PR or provide ubiquitin-protein ligase activity. This analysis revealed that in the majority of the AS patients examined, the ubiquitin-protein ligase function of E6-AP was defective whereas the coactivator function was intact. This finding suggests that the AS phenotype results from a defect in the ubiquitin-proteosome protein degradation pathway.
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Affiliation(s)
- Z Nawaz
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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Nawaz Z, Stancel GM, Hyder SM. The pure antiestrogen ICI 182,780 inhibits progestin-induced transcription. Cancer Res 1999; 59:372-6. [PMID: 9927049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
The pure antiestrogen ICI 182,780 binds to the estrogen receptor with high affinity and is currently in clinical trials for the treatment of human breast cancer. We now show for the first time that ICI 182,780 also exhibits potent antiprogestin activity at doses frequently used in laboratory investigations. The antiprogestin activity of ICI 182,780 was detected in HeLa, HepG2, and CV1 cells transiently transfected with either the A or B forms of the human progesterone receptor and a luciferase construct driven by a progesterone-response element. ICI 182,780 inhibited progesterone-induced gene transcription in a dose-dependent fashion with maximum inhibition obtained at 10(-6) M and an IC50 of approximately 2 x 10(-7) M. The ICI compound produced the same degree of inhibition as that obtained with the antiprogestin RU-486. The antiestrogen tamoxifen did not display antiprogestin activity in this test system, and ICI 182,780 did not inhibit the activity of transfected androgen or glucocorticoid receptors. These results clearly establish that ICI 182,780 has significant antiprogestin activity in addition to its well-documented antiestrogenic activity and raises the possibility that both antihormonal properties of this compound are exhibited in laboratory studies and in the course of treatment of human breast tumors.
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Affiliation(s)
- Z Nawaz
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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Shah BH, Nawaz Z, Virani SS, Ali IQ, Saeed SA, Gilani AH. The inhibitory effect of cinchonine on human platelet aggregation due to blockade of calcium influx. Biochem Pharmacol 1998; 56:955-60. [PMID: 9776305 DOI: 10.1016/s0006-2952(98)00094-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The Cinchona bark contains alkaloids like quinine, quinidine, cinchonine and cinchonidine. These agents are effective antimalarial drugs and have been used clinically in malaria caused by Plasmodium falciparum. Previous studies show that quinine and quinidine exert effects on cardiovascular system. This study was conducted to examine the effect of cinchonine on human platelet aggregation. The results show that cinchonine inhibited platelet aggregation mediated by platelet agonists, epinephrine (200 microM), ADP (4.3 microM), platelet activating factor (PAF; 800 nM) and collagen (638 nM) but had no effect on arachidonic acid (AA; 0.75 mM). Cinchonine was most effective in inhibiting aggregation induced by platelet activating factor and epinephrine with IC50 values of 125 and 180 microM respectively, however, higher concentrations of cinchonine were required to inhibit aggregation mediated by ADP or collagen (IC50; 300 microM). Pretreatment of platelets with cinchonine inhibited aggregation caused by Ca2+ ionophore, A-23187 (6 microM), in a dose-dependent manner (IC50; 300 microM) indicating an inhibitory effect on Ca2+-signaling cascade. This was supported by measuring [Ca2+]i in platelets loaded with Fura-2AM where cinchonine inhibited the rise in cytosolic Ca2+ mediated by A-23187 (6 microM) or collagen (638 nM). Results show that cinchonine (20 microM) also inhibited aggregation when platelets were pretreated with protein kinase C (PKC) activator, phorbol myristate acetate (PMA; 0.1 microM) in combination with low doses of platelet activating factor (80 nM). Cinchonine, however, had no effect on AA-induced platelet aggregation and thromboxane A2 (TXA2) synthesis in platelets. These results suggest that antiplatelet effects of cinchonine are mediated mainly through inhibition of Ca2+-influx and protein kinase C pathways in platelets.
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Affiliation(s)
- B H Shah
- Department of Physiology and Pharmacology, The Aga Khan University, Karachi, Pakistan.
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32
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Abstract
Transcriptional regulation by members of the nuclear hormone receptor superfamily is a modular process requiring the mediation of distinct subclasses of coregulators. These subclasses include members of the steroid receptor coactivator-1 (SRC-1) coactivator family, p300/CBP and their associated proteins, such as p300/CBP-associated factor, human homologs of SWI/SNF proteins such as BRG-1, and the less well-characterized E3 ubiquitin-protein ligases E6 papillomavirus protein-associated protein and receptor-potentiating factor-1. Because functional studies indicate that these coregulators may form higher order complexes, we analyzed steady-state complexes of different coregulator subclasses in vivo. T47D and HeLa cell lysates were subjected to biochemical fractionation and screened by immunoblotting using coregulator-specific antibodies. We show that different subclasses of nuclear receptor coregulators exhibit distinct fractionation profiles. Furthermore, evidence is provided that SRC-1 family members may exist in vivo in heteromultimeric forms with each other. In addition, we demonstrate that liganded PR is present in stable complexes containing SRC-1 and transcription intermediary factor 2 (TIF2) in vivo. Our results suggest that the assembly of large, modular transcriptional complexes by recruitment of distinct subclasses of preformed coregulator subcomplexes may be involved in transcriptional regulation by activated nuclear receptors.
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Affiliation(s)
- N J McKenna
- Department of Cell Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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34
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Affiliation(s)
- B H Shah
- Department of Physiology and Pharmacology, Aga Khan University, Karachi, Pakistan
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Shah BH, Safdar B, Virani SS, Nawaz Z, Saeed SA, Gilani AH. The antiplatelet aggregatory activity of Acacia nilotica is due to blockade of calcium influx through membrane calcium channels. Gen Pharmacol 1997; 29:251-5. [PMID: 9251908 DOI: 10.1016/s0306-3623(96)00413-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
1. The extract of Acacia nilotica (A. nilotica) blocked platelet aggregation mediated by platelet agonists, arachidonic acid (0.75 mM), ADP (4.3 microM), platelet activating factor (800 nM) and collagen (638 nM) in a dose-dependent manner. 2. The extract (0.21-1.4 mg/ml) blocked the platelet aggregation induced by Ca2+ ionophore, A-23187 (6 microM), in a dose-dependent manner, indicating that the Ca2+ influx is involved in aggregation. 3. The plant extract also inhibited aggregation in platelets pretreated with phorbol, 12-myristate, 13-acetate (196 nM) alone or in combination with ADP (4.3 microM), indicating an effect on protein kinase C. 4. These results indicate that the antiplatelet aggregatory activity of the extract of A. nilotica is mainly due to blockade of Ca2+ channels, although evidence also suggests the involvement of protein kinase C.
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Affiliation(s)
- B H Shah
- Department of Physiology and Pharmacology, Aga Khan University, Karachi, Pakistan.
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36
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Smith CL, Nawaz Z, O'Malley BW. Coactivator and corepressor regulation of the agonist/antagonist activity of the mixed antiestrogen, 4-hydroxytamoxifen. Mol Endocrinol 1997; 11:657-66. [PMID: 9171229 DOI: 10.1210/mend.11.6.0009] [Citation(s) in RCA: 399] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Mixed antiestrogens, such as 4-hydroxytamoxifen (4HT), act as either partial agonists or antagonists of estrogen receptor (ER) function in a tissue-, cell-, and promoter-specific manner, suggesting that intracellular factors modulate their ability to regulate transcription. To determine whether coactivators and corepressors have the capacity to modulate the relative agonist/antagonist activity of 4HT, ER-dependent gene expression was measured in the absence or presence of expression vectors for SRC-1 (steroid receptor coactivator-1) or SMRT (silencing mediator of retinoic acid and thyroid hormone receptors). In Hep G2 cells in which 4HT is an agonist, exogenous SRC-1 enhanced estradiol (E2)- and 4HT-stimulated transcription in a dose-dependent manner, while SMRT overexpression strongly reduced basal and 4HT-stimulated gene expression with no effect on E2 activity. These observations were not cell- or promoter-specific inasmuch as similar results were obtained in HeLa cells under conditions in which 4HT is an antagonist. A protein-protein interaction assay indicated that the full-length ER binds to SMRT in vitro. To assess whether relative coactivator and corepressor expression within a given cell could modulate the balance of 4HT agonist/antagonist activity, SRC-1 and SMRT were coexpressed. SMRT overexpression blocked SRC-1 coactivation of 4HT-stimulated gene expression and preferentially inhibited 4HT agonist activity whether or not exogenous SRC-1 was present. The cumulative data in this model system indicate that the relative expression of coactivators and corepressors can modulate 4HT regulation of ER transcriptional activity and suggest they could contribute to the tissue-specific ability of mixed antiestrogens to activate or inhibit ER-mediated gene expression.
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Affiliation(s)
- C L Smith
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030-3498, USA
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Shibata H, Nawaz Z, Tsai SY, O'Malley BW, Tsai MJ. Gene silencing by chicken ovalbumin upstream promoter-transcription factor I (COUP-TFI) is mediated by transcriptional corepressors, nuclear receptor-corepressor (N-CoR) and silencing mediator for retinoic acid receptor and thyroid hormone receptor (SMRT). Mol Endocrinol 1997; 11:714-24. [PMID: 9171235 DOI: 10.1210/mend.11.6.0002] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Chicken ovalbumin upstream promoter-transcription factors (COUP-TFs) are orphan receptors that belong to the steroid/thyroid hormone receptor (TR) superfamily and can repress the transcriptional activity of several target genes; however, the precise mechanism of this repression is unknown. Transfection of a Gal4 DNA-binding domain fused to the putative ligand-binding domain of COUP-TFI (Gal4-COUP-TFI) significantly represses the basal transcriptional activity of a reporter gene containing Gal4-binding sites. Cotransfection of COUP-TFI can relieve the Gal4-COUP-TFI repression in a dose-dependent manner. In contrast, COUP-TFI delta35, which lacks the repressor domain (the C-terminal 35 amino acids), fails to relieve this repression. This finding suggests that the repressor domain of COUP-TFI may squelch a limiting amount of corepressor in HeLa cells. In addition, increasing concentrations of TRbeta also can relieve the COUP-TFI repression in a hormone-sensitive manner. Similarly, overexpression of increasing concentration of COUP-TFI, but not COUP-TFI delta35, can squelch the silencing activity of the unliganded TRbeta. Collectively, these results indicate that COUP-TFI and TRbeta share a common corepressor(s) for their silencing activity. To determine which corepressor is involved in the COUP-TF-silencing activity, we used a yeast two-hybrid and in vitro GST pull-down assays to demonstrate that COUP-TFI can interact with the fragment of N-CoR (nuclear receptor-corepressor) encoding amino acids 921-2453 and the fragments of SMRT (silencing mediator for retinoic acid receptor and TR) encoding amino acids 29-564 and 565-1289, respectively. Interestingly, the fragment of SMRT encoding amino acids 1192-1495, which strongly interacts with TRbeta, interacts very weakly with COUP-TFI. Furthermore, overexpression of N-CoR or SMRT potentiates the silencing activity of COUP-TFI and can relieve the COUP-TFI-mediated squelching of Gal4-COUP-TFI activity. Therefore, our studies indicate that N-CoR and SMRT act as corepressors for the COUP-TFI silencing activity.
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Affiliation(s)
- H Shibata
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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Xu J, Nawaz Z, Tsai SY, Tsai MJ, O'Malley BW. The extreme C terminus of progesterone receptor contains a transcriptional repressor domain that functions through a putative corepressor. Proc Natl Acad Sci U S A 1996; 93:12195-9. [PMID: 8901556 PMCID: PMC37966 DOI: 10.1073/pnas.93.22.12195] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Binding of a hormone agonist to a steroid receptor leads to the dissociation of heat shock proteins, dimerization, specific DNA binding, and target gene activation. Although the progesterone antagonist RU486 can induce most of these events, it fails to activate human progesterone receptor (hPR)-dependent transcription. We have previously demonstrated that a conformational change is a key event leading to receptor activation. The major conformational distinction between hormone- and antihormone-bound receptors occurs within the C-terminal portion of the molecule. Furthermore, hPR mutants lacking the C terminus become transcriptionally active in the presence of RU486. These results suggest that the C terminus contains a repressor domain that inhibits the transcriptional activity of the RU486-bound hPR. In this study, we have defined a 12 amino acid (12AA) region in the C terminus of hPR that is necessary and sufficient for the repressor function when fused to the C-terminal truncated hPR or to the GAL4 DNA-binding domain. Mutations in the 12AA domain (aa 917-928) generate an hPR that is active in the presence of RU486. Furthermore, overexpression of the 12AA peptide activates the RU486-bound wild-type hPR without affecting progesterone-dependent activation. These results suggest that association of the 12AA repressor region with a corepressor might inactivate hPR activity when it is bound to RU486. We propose that binding of a hormone agonist to the receptor changes its conformation in the ligand-binding domain so that association with coactivator is promoted and activation of target gene occurs.
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Affiliation(s)
- J Xu
- Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030, USA
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39
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Nawaz Z, Tsai MJ, O'Malley BW. Specific mutations in the ligand binding domain selectively abolish the silencing function of human thyroid hormone receptor beta. Proc Natl Acad Sci U S A 1995; 92:11691-5. [PMID: 8524830 PMCID: PMC40468 DOI: 10.1073/pnas.92.25.11691] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Although most nuclear hormone receptors are ligand-dependent transcriptional activators, certain members of this superfamily, such as thyroid hormone receptor (TR) and retinoic acid receptor (RAR), are involved in transcriptional repression. The silencing function of these receptors has been localized to the ligand binding domain (LBD). Previously, we demonstrated that overexpression of either the entire LBD or only the N-terminal region of the LBD (amino acids 168-259) is able to inhibit the silencing activity of TR. From this result we postulated the existence of a limiting factor (corepressor) that is necessary for TR silencing activity. To support this hypothesis, we identified amino acids in the N-terminal region of the LBD of TR that are important for the corepressor interaction and for the silencing function of TR. The silencing activity of TR was unaffected by overexpression of the LBD of mutant TR (V174A/D177A), suggesting that valine at position 174 and/or aspartic acid at position 177 are important for corepressor interaction. This mutant receptor protein, V174/D177, also lost the ability to silence target genes, suggesting that these amino acids are important for silencing function. Control experiments indicate that this mutant TR maintains its wild-type hormone binding and transactivation functions. These findings further strengthen the idea that the N-terminal region of the LBD of TR interacts with a putative corepressor protein(s) to achieve silencing of basal gene transcription.
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Affiliation(s)
- Z Nawaz
- Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030, USA
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40
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Burris TP, Nawaz Z, Tsai MJ, O'Malley BW. A nuclear hormone receptor-associated protein that inhibits transactivation by the thyroid hormone and retinoic acid receptors. Proc Natl Acad Sci U S A 1995; 92:9525-9. [PMID: 7568167 PMCID: PMC40834 DOI: 10.1073/pnas.92.21.9525] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Nuclear hormone receptors are transcription factors that require multiple protein-protein interactions to regulate the expression of their target genes. Using the yeast two-hybrid system, we identified a protein, thyroid hormone receptor uncoupling protein (TRUP), that specifically interacts with a region of the human thyroid hormone receptor (TR) consisting of the hinge region and the N-terminal portion of the ligand binding domain in a hormone-independent manner. Interestingly, TRUP inhibits transactivation by TR and the retinoic acid receptor but has no effect on the estrogen receptor or the retinoid X receptor in mammalian cells. We also demonstrate that TRUP exerts its action on TR and retinoic acid receptor by interfering with their abilities to interact with their DNA. TRUP represents a type of regulatory protein that modulates the transcriptional activity of a subclass of the nuclear hormone receptor superfamily by preventing interaction with their genomic response elements.
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Affiliation(s)
- T P Burris
- Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030, USA
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41
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Hyder SM, Nawaz Z, Chiappetta C, Yokoyama K, Stancel GM. The protooncogene c-jun contains an unusual estrogen-inducible enhancer within the coding sequence. J Biol Chem 1995; 270:8506-13. [PMID: 7721748 DOI: 10.1074/jbc.270.15.8506] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Estrogens have previously been shown to induce c-jun mRNA levels in target cells during hormone induced proliferation, and this appears to be a primary hormonal response involving transcriptional activation. In this report we have now identified an estrogen dependent enhancer within the coding sequence of c-jun. This element has the sequence GCAGAnnnTGACC which is identical to the consensus estrogen response element GGTCAnnnTGACC in the second half site, but varies considerably in the first half site. Synthetic oligodeoxynucleotides containing this jun sequence bind the estrogen receptor in cell-free studies using a competitive band shift assay with the consensus element. The jun element also confers hormone inducibility to reporter plasmids in yeast and mammalian based transcriptional systems. Structure-function studies illustrate that the TGACC half-site and its immediate flanking dinucleotides, but not the GCAGA half-site, are required for estrogen receptor binding. In contrast, both the GCAGA and TGACC half-sites are obligatory for hormone-inducible transcriptional activation. These results suggest a model in which the estrogen receptor functions as a heterodimer to regulate transcription of the c-jun protooncogene. Coupled with reports of estrogen response elements in c-fos and estrogenic induction of c-fos and c-jun in vivo, these findings also support a role for AP-1 components as early response genes in estrogen-induced proliferation.
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Affiliation(s)
- S M Hyder
- Department of Pharmacology, University of Texas Medical School, Houston 77225, USA
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42
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Baniahmad C, Nawaz Z, Baniahmad A, Gleeson MA, Tsai MJ, O'Malley BW. Enhancement of human estrogen receptor activity by SPT6: a potential coactivator. Mol Endocrinol 1995; 9:34-43. [PMID: 7760849 DOI: 10.1210/mend.9.1.7760849] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The conserved nature of the transcriptional machinery between yeast and higher eukaryotes makes the yeast system suitable to genetically dissect the signal transduction pathway of steroid hormone receptors. This report describes the yeast protein, SPT6, which modulates the transcriptional activity of the human estrogen receptor (hER) by affecting the C-terminal activation domain. It is demonstrated that SPT6 is able to potentiate hER activity in yeast and also in mammalian cells in vivo. SPT6 interacts specifically with the hormone-binding domain of hER in vivo. The in vivo studies are substantiated by specific protein-protein interactions between SPT6 and the hormone-binding domain of hER in vitro. Therefore, the data suggest that the SPT6 protein may be involved in signal transmission of ER by acting as a coactivator.
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Affiliation(s)
- C Baniahmad
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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Nawaz Z, Baniahmad C, Burris TP, Stillman DJ, O'Malley BW, Tsai MJ. The yeast SIN3 gene product negatively regulates the activity of the human progesterone receptor and positively regulates the activities of GAL4 and the HAP1 activator. Mol Gen Genet 1994; 245:724-33. [PMID: 7830720 DOI: 10.1007/bf00297279] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The activation of gene transcription in eukaryotic organisms is regulated by sequence-specific DNA-binding proteins as well as by non-DNA-binding proteins. In this report we describe the modulatory functions of a non-DNA-binding protein, SIN3 (also known as SDI1, UME4, RPD1, and GAM2) on the transactivation properties of the human progesterone receptor (hPR), GAL4, and the HAP1 activator in yeast. Our data suggest that SIN3 is a dual function protein. It negatively regulates the transcriptional activities of hPR-A and hPR-B by affecting the N-terminal activation domain (AF1). SIN3 positively regulates the transcriptional activities of GAL4 and the HAP1 activator. However, it has no effect on the transcriptional activities of the human glucocorticoid receptor (hGR) and GCN4. The SIN3 protein contains four copies of a paired amphipathic helix (PAH) motif. Deletion analysis of the SIN3 PAH motifs shows that the PAH3 motif is essential for SIN3-mediated regulation of hPR, GAL4, and the HAP1 activator. In contrast, the PAH1, PAH2, and PAH4 motifs are not required for SIN3-mediated regulation of these activators. Additionally, we examined the mechanism(s) by which the SIN3 protein modulate the activities of various activators. We are unable to demonstrate the direct interaction of SIN3 protein with these activators using the yeast two-hybrid system or co-immunoprecipitation. These data suggest that SIN3 regulates the transactivation functions of hPR, GAL4, and the HAP1 activator by an indirect mechanism.
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Affiliation(s)
- Z Nawaz
- Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030
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Nawaz Z, Stancel GM, McDonnell DP, Hyder SM. Creation of an active estrogen-responsive element by a single base change in the flanking sequence of a cellular oncogene: a possible mechanism for hormonal carcinogenesis? Mol Carcinog 1993; 7:76-82. [PMID: 8457291 DOI: 10.1002/mc.2940070204] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Estrogens are considered to act as promoters in a multistep process of hormonal carcinogenesis, although the molecular mechanisms by which these hormones act in tumorigenesis are unclear at present. Estradiol is known to induce expression of certain proto-oncogenes, and this led us to examine potential regulatory regions of the cellular c-fos oncogene. The 5'-flanking region of the murine c-fos contains a 13-bp palindromic sequence (GGTCTnnnAGACC) with striking homology to the consensus estrogen-responsive element (ERE) GGTCAnnnTGACC. However, the c-fos sequence did not bind the human estrogen receptor or confer hormonal responsiveness in a yeast-based transcriptional test system. Importantly, a single base change in the fifth position of the c-fos sequence (GGTCTnnnAGACC to GGTCA/GnnnAGACC) produced an element that bound the estrogen receptor and conferred estrogen-dependent transcriptional activation of a reporter gene. This suggests a specific hypothesis by which estrogens could act as tumor promoters. In this paradigm, the regulatory region of the cellular oncogenes, tumor suppressor genes, and growth-factor genes contain inactive sequences with close homologies to hormone-responsive elements. Initiation occurs when some agent (e.g., a chemical carcinogen) causes a mutation in such a sequence to create a functional hormone-responsive element. Estrogens, acting through their receptors and the mutated element, can then activate the target gene to stimulate cell proliferation and increase the population of initiated cells.
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Affiliation(s)
- Z Nawaz
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas
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Fuqua SA, Allred DC, Elledge RM, Krieg SL, Benedix MG, Nawaz Z, O'Malley BW, Greene GL, McGuire WL. The ER-positive/PgR-negative breast cancer phenotype is not associated with mutations within the DNA binding domain. Breast Cancer Res Treat 1993; 26:191-202. [PMID: 8219256 DOI: 10.1007/bf00689692] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have used in vitro DNA binding assays as a measure of estrogen receptor (ER) function in human breast tumors. We found that the majority of ER+ (25 ER+/progesterone receptor [PgR]+, and 25 ER+/PgR-) tumors we examined were capable of binding consensus estrogen response element (ERE) oligonucleotides in this assay system. We found significant proteolytic activity in many of the tumors such that protease inhibitors were found to be essential during the preparation of tumor extracts. We next applied direct sequence analysis of the ER DNA binding domain of several of these tumors, and determined that the ER+/PgR- breast tumors did not contain mutations within the DNA binding domain which might explain their apparent discordant receptor phenotype. We did identify an alternatively spliced ER variant missing exon 3 of the DNA binding domain. This variant was unable to function as a transcriptional inducer of an estrogen-responsive reporter in a yeast assay system. Furthermore, the exon 3 ER deletion variant was expressed at equivalent levels in all of the ER+ breast tumors, so that it does not appear to be involved in the evolution of the ER+/PgR- breast cancer phenotype.
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Affiliation(s)
- S A Fuqua
- University of Texas Health Science Center, Department of Medicine/Oncology, San Antonio 78284-7884
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Hyder SM, Stancel GM, Nawaz Z, McDonnell DP, Loose-Mitchell DS. Identification of an estrogen response element in the 3'-flanking region of the murine c-fos protooncogene. J Biol Chem 1992; 267:18047-54. [PMID: 1517237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We have used transient transfection assays with reporter plasmids expressing chloramphenicol acetyltransferase, linked to regions of mouse c-fos, to identify a specific estrogen response element (ERE) in this protooncogene. This element is located in the untranslated 3'-flanking region of the c-fos gene, 5 kilobases (kb) downstream from the c-fos promoter and 1.5 kb downstream of the poly(A) signal. This element confers estrogen responsiveness to chloramphenicol acetyltransferase reporters linked to both the herpes simplex virus thymidine kinase promoter and the homologous c-fos promoter. Deletion analysis localized the response element to a 200-base pair fragment which contains the element GGTCACCACAGCC that resembles the consensus ERE sequence GGTCACAGTGACC originally identified in Xenopus vitellogenin A2 gene. A synthetic 36-base pair oligodeoxynucleotide containing this c-fos sequence conferred estrogen inducibility to the thymidine kinase promoter. The corresponding sequence also induced reporter activity when present in the c-fos gene fragment 3 kb from the thymidine kinase promoter. Gel-shift experiments demonstrated that synthetic oligonucleotides containing either the consensus ERE or the c-fos element bind human estrogen receptor obtained from a yeast expression system. However, the mobility of the shifted band is faster for the fos-ERE-complex than the consensus ERE complex suggesting that the three-dimensional structure of the protein-DNA complexes is different or that other factors are differentially involved in the two reactions. When the 5'-GGTCA sequence present in the c-fos ERE is mutated to 5'-TTTCA, transcriptional activation and receptor binding activities are both lost. Mutation of the CAGCC-3' element corresponding to the second half-site of the c-fos sequence also led to the loss of receptor binding activity, suggesting that both half-sites of this element are involved in this function. The estrogen induction mediated by either the c-fos or the consensus ERE was blunted by the antiestrogen tamoxifen. Based on these studies, we believe the 3'-fos ERE sequence we have identified may be a major cis-acting element involved in the physiological regulation of the gene by estrogens in vivo.
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Affiliation(s)
- S M Hyder
- Department of Pharmacology, University of Texas Medical School, Houston 77225
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Hyder S, Stancel G, Nawaz Z, McDonnell D, Loose-Mitchell D. Identification of an estrogen response element in the 3'-flanking region of the murine c-fos protooncogene. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)37150-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Fuqua SA, Fitzgerald SD, Allred DC, Elledge RM, Nawaz Z, McDonnell DP, O'Malley BW, Greene GL, McGuire WL. Inhibition of estrogen receptor action by a naturally occurring variant in human breast tumors. Cancer Res 1992; 52:483-6. [PMID: 1728420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
It is fairly well accepted that the presence of estrogen receptor (ER) and progesterone receptor (PgR) identifies breast cancer patients with a lower risk of relapse and better overall survival. But patients with discordant receptors, the ER+/PgR- phenotype, are often intermediate in clinical response. We focused upon this group of patients and have identified a truncated ER which is abundant in some ER+/PgR- breast tumors and which inhibits the binding of wild-type ER to its cognate response element. This variant interferes in a dominant negative manner with wild-type ER function and may represent a mechanism for modulation of estrogen responsiveness.
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Affiliation(s)
- S A Fuqua
- Department of Medical Oncology, University of Texas Health Science Center, San Antonio 78284-7884
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Nawaz Z, Tsai MJ, McDonnell DP, O'Malley BW. Identification of novel steroid-response elements. Gene Expr 1992; 2:39-47. [PMID: 1617301 PMCID: PMC6057364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/1991] [Accepted: 12/18/1991] [Indexed: 12/27/2022]
Abstract
A rapid method for defining novel steroid-responsive elements has been developed. Large libraries of degenerate oligonucleotides were analyzed using a yeast-based screen to identify estrogen-responsive DNA sequences. From a library of 40,000 recombinants, seven estrogen-responsive clones were identified. When sequenced, these elements showed remarkable diversity and were different from the consensus vitellogenin A2 ERE. One surprising result was the presence of the two half sites as direct repeats in some of the clones. This implies that in vivo estrogen receptor can bind and transactivate yeast genes through response elements in which the two half sites align as direct repeats. This protocol requires no purified protein and specifically selects for functional response elements. It has a wide application in the study of any transcription factor/DNA interaction.
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Affiliation(s)
- Z Nawaz
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030
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Abstract
We have developed a DNA interference assay in the yeast Saccharomyces cerevisiae that is designed to indicate the intracellular DNA-binding status of the estrogen receptor. The assay utilizes a promoter containing multiple copies of a GAL4-estrogen receptor binding sequence. This element is designed so that either an estrogen receptor or a GAL4 molecule, but not both, can occupy it simultaneously. The assay is extremely sensitive, and at concentrations of estrogen receptor below that required for maximal transcriptional activation of its target estrogen response element, a quantitative inhibition of GAL4-mediated transcription is seen. Inhibition occurs thought the disruption of complex cooperative interactions among the GAL4 molecules in this reporter. The data obtained from our experiments show that at low concentrations of receptor, hormone is required to promote DNA binding. Overexpression of receptor leads to occupation of the estrogen receptor element in the absence of ligand. In contrast, this latter receptor form will not activate transcription. Our results are consistent with a two-step process for receptor activation. Ligand first causes dissociation of receptor from an inhibitory complex within the cell and produces a DNA-binding form. Second, it converts receptor to a transcriptionally competent form. With use of this yeast model system, these two steps can be distinguished in situ.
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Affiliation(s)
- D P McDonnell
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030
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