Molecular hybrids of substituted phenylcarbamoylpiperidine and 1,2,4-triazole methylacetamide as potent 15-LOX inhibitors: Design, synthesis, DFT calculations and molecular docking studies

Inflammation is a multifaceted phenomenon triggered by potentially active mediators acutely released arachidonic acid metabolites partially in lipoxygenase (LOX) pathway which are primarily accountable for causing several diseases in humans. It is widely believed that an inhibitor of the LOX pathway represents a rational approach for designing more potent antiinflammatory leads with druggable super safety profiles. In our continual efforts in search for anti-LOX molecules, the present work was to design a new series of N-alkyl/aralkyl/aryl derivatives (7a-o) of 4-phenyl-5-(1-phenylcarbamoylpiperidine)-4H-1,2,4-triazole-3-thiol which was commenced in seriate formation of phenylcarbamoyl derivative (1), hydrazide (2), semicarbazide (3) and 4-phenyl-5-(1-phenylcarbamoylpiperidine)-4H-1,2,4-triazole-3-thiol (4). The aimed compounds were obtained by reacting 4-phenyl-5-(1-phenylcarbamoylpiperidine)-4H-1,2,4-triazole-3-thiol with assorted N-alkyl/aralkyl/aryl electrophiles. All compounds were characterized by FTIR, 1H-, 13C-NMR spectroscopy, EI-MS and HR-EI-MS spectrometry and screened against soybean 15-LOX for their inhibitory potential using chemiluminescence method. All the compounds except 7m and 7h inhibited the said enzyme remarkably. Compounds 7c,7l, 7j and 7a displayed potent inhibitions ranging from IC50 1.92 ± 0.13 µM to 7.65 ± 0.12 µM. Other analogues 7g, 7o, 7e, 7b, 7d, 7k and 7n revealed excellent inhibitory values ranging from IC50 12.45 ± 0.38 µM to 24.81 ± 0.47 µM. All these compounds did not reveal DPPH radical scavenging activity. Compounds 7i-o maintained > 90 % human blood mononuclear cells (MNCs) viability at 0.125 mM as assayed by MTT whilst others were found toxic. Pharmacokinetic profiles predicted good oral bioavailability and drug-likeness properties of the active scaffolds. SAR investigations showed that phenyl substituted analogue on amide side decreased inhibitory activity due to inductive and mesomeric effects while the mono-alkyl substituted analogues were more active than disubstituted ones and ortho substituted analogues were more potent than meta substituted ones. MD simulation predicted the stability of the 7c ligand and receptor complex as shown by their relative RMSD (root mean square deviation) values. Molecular docking studies displayed hydrogen bonding between the compounds and the enzyme with Arg378 which was common in 7n, 7g, 7h and baicalein. In 7a and quercetin, hydrogen bonding was established through Asn375. RMSD values exhibited good inhibitory profiles in the order quercetin (0.73 Å) < 7 g < baicalein < 7a < 7n < 7 h (1.81 Å) and the binding free energies followed similar pattern. Density functional theory (DFT) data established good correlation between the active compounds and significant activity was associated with more stabilized LUMO (lowest unoccupied molecular orbitals) orbitals. Nevertheless, the present studies declare active analogues like 7c, 7 l, 7a, 7j as leads. Work is ongoing in derivatizing active molecules to explore more effective leads as 15-LOX inhibitors as antiinflammatory agents.

A single-cell atlas identifies pretreatment features of primary imatinib resistance in chronic myeloid leukemia

Primary resistance to tyrosine kinase inhibitors (TKIs) is a significant barrier to optimal outcomes in chronic myeloid leukemia (CML), but factors contributing to response heterogeneity remain unclear. Using single-cell RNA (scRNA) sequencing, we identified 8 statistically significant features in pretreatment bone marrow, which correlated with either sensitivity (major molecular response or MMR) or extreme resistance to imatinib (eventual blast crisis [BC] transformation). Employing machine-learning, we identified leukemic stem cell (LSC) and natural killer (NK) cell gene expression profiles predicting imatinib response with >80% accuracy, including no false positives for predicting BC. A canonical erythroid-specifying (TAL1/KLF1/GATA1) regulon was a hallmark of LSCs from patients with MMR and was associated with erythroid progenitor [ERP] expansion in vivo (P < .05), and a 2- to 10-fold (6.3-fold in group A vs 1.09-fold in group C) erythroid over myeloid bias in vitro. Notably, ERPs demonstrated exquisite TKI sensitivity compared with myeloid progenitors (P < .001). These LSC features were lost with progressive resistance, and MYC- and IRF1-driven inflammatory regulons were evident in patients who progressed to transformation. Patients with MMR also exhibited a 56-fold expansion (P < .01) of a normally rare subset of hyperfunctional adaptive-like NK cells, which diminished with progressive resistance, whereas patients destined for BC accumulated inhibitory NKG2A+ NK cells favoring NK cell tolerance. Finally, we developed antibody panels to validate our scRNA-seq findings. These panels may be useful for prospective studies of primary resistance, and in assessing the contribution of predetermined vs acquired factors in TKI response heterogeneity.

Molecular mechanism of antimicrobial co-resistance Colistin (mcr-1) and ESBLs genes among Escherichia coli isolates from commercial chickens in Pakistan

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.

Single-cell and bulk transcriptome sequencing identifies two epithelial tumor cell states and refines the consensus molecular classification of colorectal cancer

The consensus molecular subtype (CMS) classification of colorectal cancer is based on bulk transcriptomics. The underlying epithelial cell diversity remains unclear. We analyzed 373,058 single-cell transcriptomes from 63 patients, focusing on 49,155 epithelial cells. We identified a pervasive genetic and transcriptomic dichotomy of malignant cells, based on distinct gene expression, DNA copy number and gene regulatory network. We recapitulated these subtypes in bulk transcriptomes from 3,614 patients. The two intrinsic subtypes, iCMS2 and iCMS3, refine CMS. iCMS3 comprises microsatellite unstable (MSI-H) cancers and one-third of microsatellite-stable (MSS) tumors. iCMS3 MSS cancers are transcriptomically more similar to MSI-H cancers than to other MSS cancers. CMS4 cancers had either iCMS2 or iCMS3 epithelium; the latter had the worst prognosis. We defined the intrinsic epithelial axis of colorectal cancer and propose a refined ‘IMF’ classification with five subtypes, combining intrinsic epithelial subtype (I), microsatellite instability status (M) and fibrosis (F).

A single-cell transcriptomic analysis of 63 patients with colorectal cancer classifies tumor cells into two epithelial subtypes. An improved tumor classification based on epithelial subtype, microsatellite stability and fibrosis reveals differences in pathway activation and metastasis.

RCA2: a scalable supervised clustering algorithm that reduces batch effects in scRNA-seq data

The transcriptomic diversity of cell types in the human body can be analysed in unprecedented detail using single cell (SC) technologies. Unsupervised clustering of SC transcriptomes, which is the default technique for defining cell types, is prone to group cells by technical, rather than biological, variation. Compared to de-novo (unsupervised) clustering, we demonstrate using multiple benchmarks that supervised clustering, which uses reference transcriptomes as a guide, is robust to batch effects and data quality artifacts. Here, we present RCA2, the first algorithm to combine reference projection (batch effect robustness) with graph-based clustering (scalability). In addition, RCA2 provides a user-friendly framework incorporating multiple commonly used downstream analysis modules. RCA2 also provides new reference panels for human and mouse and supports generation of custom panels. Furthermore, RCA2 facilitates cell type-specific QC, which is essential for accurate clustering of data from heterogeneous tissues. We demonstrate the advantages of RCA2 on SC data from human bone marrow, healthy PBMCs and PBMCs from COVID-19 patients. Scalable supervised clustering methods such as RCA2 will facilitate unified analysis of cohort-scale SC datasets.

Sero-epidemiology and risk factor analysis of human brucellosis in Punjab, Pakistan: a cross sectional study

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.

Prevalence and risk factors of Syphilis among blood donors of Punjab, Pakistan

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.

Thirty-day mortality following surgical management of hip fractures during the COVID-19 pandemic: findings from a prospective multi-centre UK study

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.

Modalities for conversion of waste to energy - Challenges and perspectives

The United Nation is achieving its sustainable development objectives by focusing on the greener technologies for waste to energy (WTE) conversion. This necessitates the exploration of every conceivable sustainable route in different sectors. Among these, sustainable bio-economy, electricity, and waste management are the most dynamic areas. However, till now sustainability judgments for the generation of electricity from waste-to-energy supply chain (WTE-SC) technologies have been restricted in scale with respect to the three-dimensional sustainability structure (social, environmental, and economic). In most of the cases, the assessments were controlled by various environmental factors/indicators, via overlooking the economic and social indicators. In this review, we have tried to summarize a variety of state-of-the-art WTE technologies including biological and thermal treatment, landfill gas utilization and biorefineries technologies etc. These technologies can be implemented by various policy makers and agencies to deal with the communities fear before spreading and executing the relevant rules and regulations. The implementation of these rules and regulations for WTE-SC were scheduled to decide the barriers and challenges from the perspective of finance, institution, technology, and regulation.

The Role and Welfare of Cart Donkeys Used in Waste Management in Karachi, Pakistan

Simple Summary

In low and middle-income countries, equids (donkeys, horses, and mules) play a critical role in supporting people’s livelihoods. In Karachi, donkey carts are used to transport building materials, commercial produce and garbage. However, to date the role of donkeys in waste management has received little attention. This study therefore aimed to articulate the role and welfare of donkeys used in waste management. Interviews were conducted with donkey owners, households that use donkey carts to collect their waste and key informants. We found that the collection of waste was the primary source of income for 89% of donkey owners interviewed; of those working in waste management, 62% were under 18 years of age. Households reported removal of waste by donkey cart as their preferred waste management option, and reported that there would be a huge garbage build-up if donkey carts became unavailable. A number of animal welfare concerns were documented; 52.9% of donkeys had a body condition score of two. Muzzle mutilation was extremely high (78.4%) and 66.7% of donkeys had superficial knee lesions. We recommend that appropriate public resources are allocated to improve the welfare of both donkeys and people working in waste management in Pakistan.

Abstract

Equine ownership is a common income-generating strategy in Pakistan. In Karachi, donkey carts are used to transport building materials, commercial produce and garbage. This study aimed to articulate the role and welfare of donkeys used in waste management. We conducted interviews with donkey owners (n = 200), households which use donkey carts for waste collection (n = 50) and key informants (n = 14). To assess the welfare of donkeys, the Standardised Equine-Based Welfare Assessment Tool (SEBWAT) was used (n = 204). Collection of waste was the primary source of income for 89% of owners interviewed. Of those directly involved in waste collection, 62% were found to be under 18 years of age. During interviews with donkey cart customers the majority reported that there would be a huge garbage build-up if donkey carts were not available. Welfare assessments demonstrated that 52.9% of donkeys had a body condition score of two. Muzzle mutilation was extremely high (78.4%) and 66.7% of donkeys had superficial knee lesions. This is the first study that has explored the role of donkey carts in waste management in Pakistan. The data demonstrate the sizable role that donkey-owning communities play in waste management and the important livelihood option this offers, as well as considerable animal welfare concerns.

Rhizosphere-associated Alcaligenes and Bacillus strains that induce resistance against blast and sheath blight diseases, enhance plant growth and improve mineral content in rice

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.

Impact of somatic copy number alterations on the glioblastoma miRNome: miR-4484 is a genomically deleted tumour suppressor

Glioblastoma (GBM) is the most frequent and most malignant primary brain tumour in adults. GBMs have a unique landscape of somatic copy number alterations (SCNAs), with the concomitant appearance of numerous driver amplifications and deletions. Here, we examined the genomic regions harbouring SCNAs and their impact on the GBM miRNome. We found that 40% of SCNA events covering 70–88% of the genomically altered regions, as identified by GISTIC and RAE algorithms, carried miRNA genes. Of 1426 annotated mature miRNAs analysed, ~ 14% (n = 198) were mapped to such fragile loci. Further, we identified an intragenic miRNA, miR‐4484 located on chromosome‐10, as a deleted and downregulated miRNA in GBM. miR‐4484 exhibited a strong positive correlation with the expression of its host gene uroporphyrinogen III synthase (UROS), thereby indicating that the loss of miR‐4484 is a codeletion event in GBM. Overexpression of miR‐4484 reduced the colony‐forming ability and suppressed the migratory capacity of glioma cells. Analysis of the RNA‐seq‐derived transcriptome upon exogenous miR‐4484 overexpression in conjunction with an integrative bioinformatics approach revealed several putative targets of miR‐4484. Unbiased functional enrichment of these targets through DAVID identified a cohort of important gene ontology terms, which possibly explain the functional role of miR‐4484 in gliomagenesis. Selected targets were validated and, importantly, were found to be upregulated in GBM. In brief, our study identified a panel of miRNAs that are likely to be regulated by genomic deletions and amplifications. Further, miR‐4484 was found to be deleted and acts as a tumour suppressor miRNA in GBM.

PI3 kinase pathway regulated miRNome in glioblastoma: identification of miR-326 as a tumour suppressor miRNA

Background

Glioblastomas (GBM) continue to remain one of the most dreaded tumours that are highly infiltrative in nature and easily preclude comprehensive surgical resection. GBMs pose an intricate etiology as they are being associated with a plethora of genetic and epigenetic lesions. Misregulation of the PI3 kinase pathway is one of the most familiar events in GBM. While the PI3 kinase signalling regulated pathways and genes have been comprehensively studied, its impact on the miRNome is yet to be explored. The objective of this study was to elucidate the PI3 kinase pathway regulated miRNAs in GBM.

Methods

miRNA expression profiling was conducted to monitor the differentially regulated miRNAs upon PI3 kinase pathway abrogation. qRT-PCR was used to measure the abundance of miR-326 and its host gene encoded transcript. Proliferation assay, colony suppression assay and wound healing assay were carried out in pre-miR transfected cells to investigate its role in malignant transformation. Potential targets of miR-326 were identified by transcriptome analysis of miR-326 overexpressing cells by whole RNA sequencing and selected targets were validated. Several publically available data sets were used for various investigations described above.

Results

We identified several miRNA that were regulated by PI3 kinase pathway. miR-326, a GBM downregulated miRNA, was validated as one of the miRNAs whose expression was alleviated upon abrogation of the PI3 kinase pathway. Overexpression of miR-326 resulted in reduced proliferation, colony suppression and hindered the migration capacity of glioma cells. Arrestin, Beta 1 (ARRB1), the host gene of miR-326, was also downregulated in GBM and interestingly, the expression of ARRB1 was also alleviated upon inhibition of the PI3 kinase pathway, indicating similar regulation pattern. More importantly, miR-326 exhibited a significant positive correlation with ARRB1 in terms of its expression. Transcriptome analysis upon miR-326 overexpression coupled with integrative bioinformatics approach identified several putative targets of miR-326. Selected targets were validated and interestingly found to be upregulated in GBM.

Conclusions

Taken together, our study uncovered the PI3 kinase regulated miRNome in GBM. miR-326, a PI3 kinase pathway inhibited miRNA, was demonstrated as a tumour suppressor miRNA in GBM.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-016-0557-8) contains supplementary material, which is available to authorized users.

A consortium of rhizobacterial strains and biochemical growth elicitors improve cold and drought stress tolerance in rice (Oryza sativa L.)

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.

Impact of the Pro12Ala polymorphism of the PPARγ2 gene on diabetes and obesity in a highly consanguineous population

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.

Pattern of glomerular disease in the Saudi population: a single-center, five-year retrospective study

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.

Whole exome sequencing unravels disease-causing genes in consanguineous families in Qatar

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.

Insulin growth factor-2 binding protein 3 (IGF2BP3) is a glioblastoma-specific marker that activates phosphatidylinositol 3-kinase/mitogen-activated protein kinase (PI3K/MAPK) pathways by modulating IGF-2

Glioblastoma is the most common and malignant form of primary astrocytoma. Upon investigation of the insulin-like growth factor (IGF) pathway, we found the IGF2BP3/IMP3 transcript and protein to be up-regulated in GBMs but not in lower grade astrocytomas (p < 0.0001). IMP3 is an RNA binding protein known to bind to the 5′-untranslated region of IGF-2 mRNA, thereby activating its translation. Overexpression- and knockdown-based studies establish a role for IMP3 in promoting proliferation, anchorage-independent growth, invasion, and chemoresistance. IMP3 overexpressing B16F10 cells also showed increased tumor growth, angiogenesis, and metastasis, resulting in poor survival in a mouse model. Additionally, the infiltrating front, perivascular, and subpial regions in a majority of the GBMs stained positive for IMP3. Furthermore, two different murine glioma models were used to substantiate the above findings. In agreement with the translation activation functions of IMP3, we also found increased IGF-2 protein in the GBM tumor samples without a corresponding increase in its transcript levels. Also, in vitro IMP3 overexpression/knockdown modulated the IGF-2 protein levels without altering its transcript levels. Additionally, IGF-2 neutralization and supplementation studies established that the proproliferative effects of IMP3 were indeed mediated through IGF-2. Concordantly, PI3K and MAPK, the downstream effectors of IGF-2, are activated by IMP3 and are found to be essential for IMP3-induced cell proliferation. Thus, we have identified IMP3 as a GBM-specific proproliferative and proinvasive marker acting through IGF-2 resulting in the activation of oncogenic PI3K and MAPK pathways.

Retrieval analysis of 240 metal-on-metal hip components, comparing modular total hip replacement with hip resurfacing

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.

The clinical and genetic epidemiology of neuronal ceroid lipofuscinosis in Newfoundland

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.

Mucin expression profile in Barrett's, dysplasia, adenocarcinoma sequence in the esophagus

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.

Importance of the regulation of nuclear receptor degradation

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.

Forkhead homologue in rhabdomyosarcoma functions as a bifunctional nuclear receptor-interacting protein with both coactivator and corepressor functions

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.

Regulation of vascular endothelial growth factor expression by estrogens and progestins

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.

Both corepressor proteins SMRT and N-CoR exist in large protein complexes containing HDAC3

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.

The dual function steroid receptor coactivator/ubiquitin protein-ligase integrator E6-AP is overexpressed in mouse mammary tumorigenesis

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.

Identification of functional estrogen response elements in the gene coding for the potent angiogenic factor vascular endothelial growth factor

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.

The 26S proteasome is required for estrogen receptor-alpha and coactivator turnover and for efficient estrogen receptor-alpha transactivation

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.

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

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.

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

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.

Nuclear receptor coactivators: multiple enzymes, multiple complexes, multiple functions

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.

Proteasome-dependent degradation of the human estrogen receptor

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.

The Angelman syndrome-associated protein, E6-AP, is a coactivator for the nuclear hormone receptor superfamily

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.

The pure antiestrogen ICI 182,780 inhibits progestin-induced transcription

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.

The inhibitory effect of cinchonine on human platelet aggregation due to blockade of calcium influx

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.

Distinct steady-state nuclear receptor coregulator complexes exist in vivo

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.

The antiplatelet aggregatory activity of Acacia nilotica is due to blockade of calcium influx through membrane calcium channels

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.

Coactivator and corepressor regulation of the agonist/antagonist activity of the mixed antiestrogen, 4-hydroxytamoxifen

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.

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)

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.

The extreme C terminus of progesterone receptor contains a transcriptional repressor domain that functions through a putative corepressor

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.

Specific mutations in the ligand binding domain selectively abolish the silencing function of human thyroid hormone receptor beta

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.

A nuclear hormone receptor-associated protein that inhibits transactivation by the thyroid hormone and retinoic acid receptors

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.