Involvement of a specificity proteins-binding element in regulation of basal and estrogen-induced transcription activity of the BRCA1 gene

INTRODUCTION:Increased estrogen level has been regarded to be a risk factor for breast cancer. However, estrogen has also been shown to induce the expression of the tumor suppressor gene, BRCA1. Upregulation of BRCA1 is thought to be a feedback mechanism for controlling DNA repair in proliferating cells. Estrogens enhance transcription of target genes by stimulating the association of the estrogen receptor (ER) and related coactivators to estrogen response elements or to transcription complexes formed at activator protein (AP)-1 or specificity protein (Sp)-binding sites. Interestingly, the BRCA1 gene lacks a consensus estrogen response element. We previously reported that estrogen stimulated BRCA1 transcription through the recruitment of a p300/ER-alpha complex to an AP-1 site harbored in the proximal BRCA1 promoter. The purpose of the study was to analyze the contribution of cis-acting sites flanking the AP-1 element to basal and estrogen-dependent regulation of BRCA1 transcription.METHODS:Using transfection studies with wild-type and mutated BRCA1 promoter constructs, electromobility binding and shift assays, and DNA-protein interaction and chromatin immunoprecipitation assays, we investigated the role of Sp-binding sites and cAMP response element (CRE)-binding sites harbored in the proximal BRCA1 promoter.RESULTS:We report that in the BRCA1 promoter the AP-1 site is flanked upstream by an element (5'-GGGGCGGAA-3') that recruits Sp1, Sp3, and Sp4 factors, and downstream by a half CRE-binding motif (5'-CGTAA-3') that binds CRE-binding protein. In ER-alpha-positive MCF-7 cells and ER-alpha-negative Hela cells expressing exogenous ER-alpha, mutation of the Sp-binding site interfered with basal and estrogen-induced BRCA1 transcription. Conversely, mutation of the CRE-binding element reduced basal BRCA1 promoter activity but did not prevent estrogen activation. In combination with the AP-1/CRE sites, the Sp-binding domain enhanced the recruitment of nuclear proteins to the BRCA1 promoter. Finally, we report that the MEK1 (mitogen-activated protein kinase kinase-1) inhibitor PD98059 attenuated the recruitment of Sp1 and phosphorylated ER-alpha, respectively, to the Sp and AP-1 binding element.CONCLUSION:These cumulative findings suggest that the proximal BRCA1 promoter segment comprises cis-acting elements that are targeted by Sp-binding and CRE-binding proteins that contribute to regulation of BRCA1 transcription.This item is part of the UA Faculty Publications collection. For more information this item or other items in the UA Campus Repository, contact the University of Arizona Libraries at [email protected]

Changes of cellular expression of mRNA for tropoelastin in the intraembryonic arterial vessels of developing chick revealed by in situ hybridization.

The pattern of expression of tropoelastin mRNA in the arterial tree of developing chick has been studied by in situ hybridization. Significant hybridization was noted in 5.5-day embryos in the region of the truncus arteriosus where aorta and pulmonary artery had newly separated. The activation of expression then propagated centrifugally and longitudinal gradients of mRNA decreasing from the heart to the periphery were established. For almost two-thirds of the embryonic period, the hybridization signal was rather uniform over the entire wall of the arterial vessels. Later, however, its distribution varied depending on the type of artery (elastic or muscular) and on the developmental stage. A radial gradient of tropoelastin mRNA expression decreasing in the in-out direction was formed in elastic arteries. This was first seen in the pulmonary artery (15-day chick embryos) and became detectable in the vessels of the general circulation only much later (2 weeks after hatching). The appearance of the radial gradient was followed by a general reduction of mRNA synthesis. In muscular arteries radial gradients were also established, but had, however, an opposite polarity; in small arteries a ring of hybridization was evident at the media-adventitia border. The results indicate that the expression of the tropoelastin gene in cells of the arterial wall is finely regulated, depending on the coordinates in the arterial tree, the type of artery and the organ supplied

MYOD modified mRNA drives direct on-chip programming of human pluripotent stem cells into skeletal myocytes

Drug screening and disease modelling for skeletal muscle related pathologies would strongly benefit from the integration of myogenic cells derived from human pluripotent stem cells within miniaturized cell culture devices, such as microfluidic platform. Here, we identified the optimal culture conditions that allow direct differentiation of human pluripotent stem cells in myogenic cells within microfluidic devices. Myogenic cells are efficiently derived from both human embryonic (hESC) or induced pluripotent stem cells (hiPSC) in eleven days by combining small molecules and non-integrating modified mRNA (mmRNA) encoding for the master myogenic transcription factor MYOD. Our work opens new perspective for the development of patient-specific platforms in which a one-step myogenic differentiation could be used to generate skeletal muscle on-a-chip

The droopy shoulder syndrome

Droopy shoulder syndrome (DSS) is characterized by a depression of the shoulders that stretches the brachial plexus, thus causing pain without any signs of neurological impairment. We describe ten patients with DSS; all had been treated for different diagnoses before. Contrary to previous reports, three patients had unilateral involvement, and five had accompanying disease of the cervical-shoulder region. All patients responded well to conservative treatment in 2-10 weeks. DSS must be kept in mind in the differential diagnosis of pain in the cervical-shoulder region, to prevent unnecessary medication

Treatment of carpal tunnel syndrome with nerve and tendon gliding exercises

Objective: To assess the effect of nerve and tendon gliding exercises in carpal tunnel syndrome

An atypical psoriatic spondylitis case, successfully treated with methotrexate

We present a 45 - year-old male patient who was hospitalized with lumbar disc herniation and whose control magnetic resonance imaging (MRI) findings initially suggested brucella spondylitis. Definitive diagnosis, however, indicated psoriatic spondylitis and the patient was succesfully treated with methotrexate. A diagnosis of lumbar disc herniation was made in May 1991, during his psoriasis vulgaris treatment. He was hospitalized in August 1994 with a complaint of low-back pain persisting over the last six months despite treatment with analgesics. He was evaluated by clinical, radiological, laboratory and scintigraphic methods, following control MRI findings suggesting infection of vertebral bodies, particularly pointing to brucellosis in addition to disc herniation. A diagnosis of psoriatic spondylitis was finally established and 7.5 mg methotrexate weekly was administered. Significant improvement was obtained of psoriatic skin lesions, low-back pain and MRI findings through a six-month treatment period

Bone mineral density in asthmatic patients using low dose inhaled gluclocorticosteroids

Inhaled glucocorticosteroids are clearly beneficial in subjects with moderate or severe asthma since they are well tolerated, reduce symptoms, and improve quality of life. Some studies suggest that inhaled glucocorticosteroids can adversely affect bone mineral density. The aim of this study is to determine the effects of inhaled glucocorticosteroid therapy on bone mineral density in female patients. Forty-five asthmatic female patients (36 premenopousal and 9 postmenopausal) and forty-six healthy control subjects were included in the study. Bone mineral density was measured from lumbar spine (L1-4) and femur (neck, trochanter, and Ward's triangle) by dual energy X-Ray absorptiometry. Age, occupation, menopause and smoking status, alcohol consumption, body mass index, previous fractures, family history of fractures, menstrual history, ooferectomy, number of pregnancies, the duration of lactation, physical activity and calcium intake were questioned according to the European Vertebral Osteoporosis Study Group (EVOS) form. Cumulative inhaled glucocorticosteroid dose was calculated. T score of femoral neck and T score and bone mineral density of Ward's triangle were significantly lower in asthmatic patients compared to control group but no statistically significant correlation was found between the disease duration, inhaled steroid treatment duration, cumulative inhaled dose and annual inhaled steroid dose and bone mineral density measurement. These results suggest that in asthmatic patients using low dose inhaled corticosteroids bone mineral density is lower than in healthy controls but it is still unclear if asthma by itself is a risk factor for osteoporosis