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Institution

Howard Hughes Medical Institute

NonprofitChevy Chase, Maryland, United States
About: Howard Hughes Medical Institute is a nonprofit organization based out in Chevy Chase, Maryland, United States. It is known for research contribution in the topics: Gene & RNA. The organization has 20371 authors who have published 34677 publications receiving 5247143 citations. The organization is also known as: HHMI & hhmi.org.


Papers
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Journal ArticleDOI
TL;DR: It is shown that Arf binds to the product of the Mdm2 gene and sequesters it into the nucleolus, thereby preventing negative-feedback regulation of p53 by MDM2 and leading to the activation of p 53 in the nucleoplasm.
Abstract: The Ink4/Arf locus encodes two tumour-suppressor proteins, p16Ink4a and p19Arf, that govern the antiproliferative functions of the retinoblastoma and p53 proteins, respectively. Here we show that Arf binds to the product of the Mdm2 gene and sequesters it into the nucleolus, thereby preventing negative-feedback regulation of p53 by Mdm2 and leading to the activation of p53 in the nucleoplasm. Arf and Mdm2 co-localize in the nucleolus in response to activation of the oncoprotein Myc and as mouse fibroblasts undergo replicative senescence. These topological interactions of Arf and Mdm2 point towards a new mechanism for p53 activation.

965 citations

Journal ArticleDOI
TL;DR: It is proposed that senescence is a multistep process requiring the expression of both p21 and p16, which may explain why p16 but not p21 is commonly mutated in immortal cells and human tumors.
Abstract: Human diploid fibroblasts (HDFs) can be grown in culture for a finite number of population doublings before they cease proliferation and enter a growth-arrest state termed replicative senescence. The retinoblastoma gene product, Rb, expressed in these cells is hypophosphorylated. To determine a possible mechanism by which senescent human fibroblasts maintain a hypophosphorylated Rb, we examined the expression levels and interaction of the Rb kinases, CDK4 and CDK6, and the cyclin-dependent kinase inhibitors p21 and p16 in senescent HDFs. Cellular p21 protein expression increased dramatically during the final two to three passages when the majority of cells lost their growth potential and neared senescence but p21 levels declined in senescent HDFs. During this period, p16 mRNA and cellular protein levels gradually rose with the protein levels in senescent HDFs reaching nearly 40-fold higher than early passage cells. In senescent HDFs, p16 was shown to be complexed to both CDK4 and CDK6. Immunodepletion analysis of p21 and p16 from the senescent cell extracts revealed that p16 is the major CDK inhibitor for both CDK4 and CDK6 kinases. Immunoprecipitation of CDK4 and CDK6 and their associated proteins from radiolabeled extracts from senescent HDFs showed no other CDK inhibitors. Based upon these results, we propose that senescence is a multistep process requiring the expression of both p21 and p16. p16 up-regulation is a key event in the terminal stages of growth arrest in senescence, which may explain why p16 but not p21 is commonly mutated in immortal cells and human tumors.

964 citations

Journal ArticleDOI
06 Feb 2003-Nature
TL;DR: It is reported that a loss-of-function (E1425G) mutation in ankyrin-B, a member of a family of versatile membrane adapters, causes dominantly inherited type 4 long-QT cardiac arrhythmia in humans.
Abstract: Mutations in ion channels involved in the generation and termination of action potentials constitute a family of molecular defects that underlie fatal cardiac arrhythmias in inherited long-QT syndrome. We report here that a loss-of-function (E1425G) mutation in ankyrin-B (also known as ankyrin 2), a member of a family of versatile membrane adapters, causes dominantly inherited type 4 long-QT cardiac arrhythmia in humans. Mice heterozygous for a null mutation in ankyrin-B are haploinsufficient and display arrhythmia similar to humans. Mutation of ankyrin-B results in disruption in the cellular organization of the sodium pump, the sodium/calcium exchanger, and inositol-1,4,5-trisphosphate receptors (all ankyrin-B-binding proteins), which reduces the targeting of these proteins to the transverse tubules as well as reducing overall protein level. Ankyrin-B mutation also leads to altered Ca2+ signalling in adult cardiomyocytes that results in extrasystoles, and provides a rationale for the arrhythmia. Thus, we identify a new mechanism for cardiac arrhythmia due to abnormal coordination of multiple functionally related ion channels and transporters.

962 citations

Journal ArticleDOI
19 Jan 1996-Science
TL;DR: Overexpression of β-arrestins in human embryonic kidney cells rescued the sequestration of β2-adrenergic receptor (β2AR) mutants defective in their ability to sequester, an effect enhanced by simultaneous overexpressionof β-adenergic receptor kinase 1 and two β-Arrestin mutants.
Abstract: β-Arrestins are proteins that bind phosphorylated heterotrimeric GTP-binding protein (G protein)-coupled receptors (GPCRs) and contribute to the desensitization of GPCRs by uncoupling the signal transduction process Resensitization of GPCR responsiveness involves agonist-mediated receptor sequestration Overexpression of β-arrestins in human embryonic kidney cells rescued the sequestration of β 2 -adrenergic receptor (β 2 AR) mutants defective in their ability to sequester, an effect enhanced by simultaneous overexpression of β-adrenergic receptor kinase 1 Wild-type β 2 AR sequestration was inhibited by the overexpression of two β-arrestin mutants These findings suggest that β-arrestins play an integral role in GPCR internalization and thus serve a dual role in the regulation of GPCR function

962 citations

Journal ArticleDOI
TL;DR: In 32D myeloid progenitor cells, phosphorylation of Ser307 inhibited insulin stimulation of the phosphatidylinositol 3-kinase and MAPK cascades, suggesting that inhibition of PTB domain function in IRS-1 by phosphorylated Ser307 might be a general mechanism to regulate insulin signaling.

961 citations


Authors

Showing all 20486 results

NameH-indexPapersCitations
Bert Vogelstein247757332094
Richard A. Flavell2311328205119
Steven A. Rosenberg2181204199262
Kenneth W. Kinzler215640243944
Robert J. Lefkowitz214860147995
Rob Knight2011061253207
Irving L. Weissman2011141172504
Ronald M. Evans199708166722
Francis S. Collins196743250787
Craig B. Thompson195557173172
Thomas C. Südhof191653118007
Joan Massagué189408149951
Stuart H. Orkin186715112182
John P. A. Ioannidis1851311193612
Eric R. Kandel184603113560
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202330
2022228
20211,583
20201,587
20191,591
20181,394