Rockefeller University

About: Rockefeller University is a education organization based out in New York, New York, United States. It is known for research contribution in the topics: Population & Gene. The organization has 15867 authors who have published 32938 publications receiving 2940261 citations. The organization is also known as: Rockefeller University & Rockefeller Institute.

Claudin-1 is a hepatitis C virus co-receptor required for a late step in entry.

Abstract: Hepatitis C virus (HCV) is a leading cause of cirrhosis and liver cancer worldwide. A better understanding of the viral life cycle, including the mechanisms of entry into host cells, is needed to identify novel therapeutic targets. Although HCV entry requires the CD81 co-receptor, and other host molecules have been implicated, at least one factor critical to this process remains unknown (reviewed in refs 1-3). Using an iterative expression cloning approach we identified claudin-1 (CLDN1), a tight junction component that is highly expressed in the liver, as essential for HCV entry. CLDN1 is required for HCV infection of human hepatoma cell lines and is the first factor to confer susceptibility to HCV when ectopically expressed in non-hepatic cells. Discrete residues within the first extracellular loop (EL1) of CLDN1, but not protein interaction motifs in intracellular domains, are critical for HCV entry. Moreover, antibodies directed against an epitope inserted in the CLDN1 EL1 block HCV infection. The kinetics of this inhibition indicate that CLDN1 acts late in the entry process, after virus binding and interaction with the HCV co-receptor CD81. With CLDN1 we have identified a novel key factor for HCV entry and a new target for antiviral drug development.

Correlation of Glucose Regulation and Hemoglobin AIc in Diabetes Mellitus

Abstract: We studied the increased levels of hemoglobins AIa+Ib and AIc in five hospitalized diabetic patients to determine whether changes in diabetic control would cause parallel changes in the levels of these hemoglobins. Before control of diabetes the mean fasting blood sugar for all patients was 343 mg per deciliter (range, 280 to 450), and hemoglobin AIc concentration 9.8 per cent (range, 6.8 to 12.1). During optimal diabetic control the blood sugar concentration was 84 mg per deciliter (range, 70 to 100), and hemoglobin AIc concentration 5.8 per cent (range, 4.2 to 7.6). Hemoglobin AIc concentration appears to reflect the mean blood sugar concentration best over previous weeks to months. The periodic monitoring of hemoglobin AIc levels provides a useful way of documenting the degree of control of glucose metabolism in diabetic patients and provides a means whereby the relation of carbohydrate control to the development of sequelae can be assessed.

Control of telomere length by the human telomeric protein TRF1.

Abstract: Human telomeres, the nucleoprotein complexes at chromosome ends, consist of tandem arrays of TTAGGG repeats bound to specific proteins. In normal human cells, telomeres shorten with successive cell divisions, probably due to the terminal sequence loss that accompanies DNA replication. In tumours and immortalized cells, this decline is halted through the activation of telomerase, a reverse transcriptase that extends the telomeric TTAGGG-repeat arrays. Telomere length is stable in several immortal human-cell lines, suggesting that a regulatory mechanism exists for limiting telomere elongation by telomerase. Here we show that the human telomeric-repeat binding factor TRF1 (ref. 8) is involved in this regulation. Long-term overexpression of TRF1 in the telomerase-positive tumour-cell line HT1080 resulted in a gradual and progressive telomere shortening. Conversely, telomere elongation was induced by expression of a dominant-negative TRF1 mutant that inhibited binding of endogenous TRF1 to telomeres. Our results identify TRF1 as a suppressor of telomere elongation and indicate that TRF1 is involved in the negative feedback mechanism that stabilizes telomere length. As TRF1 does not detectably affect the expression of telomerase, we propose that the binding of TRF1 controls telomere length in cis by inhibiting the action of telomerase at the ends of individual telomeres.

Estradiol mediates fluctuation in hippocampal synapse density during the estrous cycle in the adult rat.

Abstract: We have found that the density of synapses in the stratum radiatum of the hippocampal CA1 region in the adult female rat is sensitive to estradiol manipulation and fluctuates naturally as the levels of ovarian steroids vary during the 5 d estrous cycle. In both cases, low levels of estradiol are correlated with lower synapse density, while high estradiol levels are correlated with a higher density of synapses. These synaptic changes occur very rapidly in that within approximately 24 hr between the proestrus and estrus stages of the estrous cycle, we observe a 32% decrease in the density of hippocampal synapses. Synapse density then appears to cycle back to proestrus values over a period of several days. To our knowledge, this is the first demonstration of such short-term steroid-mediated synaptic plasticity occurring naturally in the adult mammalian brain.

Co-crystal structure of the HNF-3/ fork head DNA-recognition motif resembles histone H5

Abstract: The three-dimensional structure of an HNF-3/fork head DNA-recognition motif complexed with DNA has been determined by X-ray crystallography at 2.5 A resolution. This alpha/beta protein binds B-DNA as a monomer, through interactions with the DNA backbone and through both direct and water-mediated major and minor groove base contacts, inducing a 13 degrees bend. The transcription factor fold is very similar to the structure of histone H5. In its amino-terminal half, three alpha-helices adopt a compact structure that presents the third helix to the major groove. The remainder of the protein includes a twisted, antiparallel beta-structure and random coil that interacts with the minor groove.