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Zelton D Sharp

Bio: Zelton D Sharp is an academic researcher from University of Texas at Austin. The author has contributed to research in topics: Transcription (biology) & Cancer. The author has an hindex of 25, co-authored 54 publications receiving 5735 citations. Previous affiliations of Zelton D Sharp include University of Texas System & University of Texas Health Science Center at San Antonio.


Papers
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Journal ArticleDOI
16 Jul 2009-Nature
TL;DR: It is reported that rapamycin, an inhibitor of the mTOR pathway, extends median and maximal lifespan of both male and female mice when fed beginning at 600 days of age.
Abstract: Inhibition of the TOR signalling pathway by genetic or pharmacological intervention extends lifespan in invertebrates, including yeast, nematodes and fruitflies; however, whether inhibition of mTOR signalling can extend lifespan in a mammalian species was unknown. Here we report that rapamycin, an inhibitor of the mTOR pathway, extends median and maximal lifespan of both male and female mice when fed beginning at 600 days of age. On the basis of age at 90% mortality, rapamycin led to an increase of 14% for females and 9% for males. The effect was seen at three independent test sites in genetically heterogeneous mice, chosen to avoid genotype-specific effects on disease susceptibility. Disease patterns of rapamycin-treated mice did not differ from those of control mice. In a separate study, rapamycin fed to mice beginning at 270 days of age also increased survival in both males and females, based on an interim analysis conducted near the median survival point. Rapamycin may extend lifespan by postponing death from cancer, by retarding mechanisms of ageing, or both. To our knowledge, these are the first results to demonstrate a role for mTOR signalling in the regulation of mammalian lifespan, as well as pharmacological extension of lifespan in both genders. These findings have implications for further development of interventions targeting mTOR for the treatment and prevention of age-related diseases.

3,216 citations

Journal ArticleDOI
TL;DR: Evaluation of rapamycin's effects on mice is likely to help delineate the role of the mammalian target ofRapamycin complexes in the regulation of aging rate and age-dependent diseases and may help to guide a search for drugs that retard some or all of the diseases of aging.
Abstract: Rapamycin was administered in food to genetically heterogeneous mice from the age of 9 months and produced significant increases in life span, including maximum life span, at each of three test sites. Median survival was extended by an average of 10% in males and 18% in females. Rapamycin attenuated age-associated decline in spontaneous activity in males but not in females. Causes of death were similar in control and rapamycin-treated mice. Resveratrol (at 300 and 1200 ppm food) and simvastatin (12 and 120 ppm) did not have significant effects on survival in male or female mice. Further evaluation of rapamycin's effects on mice is likely to help delineate the role of the mammalian target of rapamycin complexes in the regulation of aging rate and age-dependent diseases and may help to guide a search for drugs that retard some or all of the diseases of aging.

805 citations

Journal ArticleDOI
TL;DR: Some of the endocrine and metabolic changes seen in diet‐restricted mice are not seen in mice exposed toRapamycin, and the pattern of expression of hepatic genes involved in xenobiotic metabolism is also quite distinct in rapamycin‐treated and diet‐ restricted mice, suggesting that these two interventions for extending mouse lifespan differ in many respects.
Abstract: Rapamycin, an inhibitor of mTOR kinase, increased median lifespan of genetically heterogeneous mice by 23% (males) to 26% (females) when tested at a dose threefold higher than that used in our previous studies; maximal longevity was also increased in both sexes. Rapamycin increased lifespan more in females than in males at each dose evaluated, perhaps reflecting sexual dimorphism in blood levels of this drug. Some of the endocrine and metabolic changes seen in diet-restricted mice are not seen in mice exposed to rapamycin, and the pattern of expression of hepatic genes involved in xenobiotic metabolism is also quite distinct in rapamycin-treated and diet-restricted mice, suggesting that these two interventions for extending mouse lifespan differ in many respects.

461 citations

Journal ArticleDOI
TL;DR: In this article, specific antibodies were prepared that identified the gene product of BRCA2 as a 390-kDa nuclear protein, and direct binding of human RAD51 to each of the four single 30-amino acid BRC repeats located at the 5′ portion of exon 11 of bRCa2 was demonstrated.
Abstract: The BRCA2 gene was identified based on its involvement in familial breast cancer. The analysis of its sequence predicts that the gene encodes a protein with 3,418 amino acids but provides very few clues pointing to its biological function. In an attempt to address this question, specific antibodies were prepared that identified the gene product of BRCA2 as a 390-kDa nuclear protein. Furthermore, direct binding of human RAD51 to each of the four single 30-amino acid BRC repeats located at the 5′ portion of exon 11 of BRCA2 was demonstrated. Such an interaction is significant, as BRCA2 and RAD51 can be reciprocally coimmunoprecipitated by each of the individual, specific antibodies and form complexes in vivo. Inferring from the function of RAD51 in DNA repair, human pancreatic cancer cells, Capan-1, expressing truncated BRCA2 were shown to be hypersensitive to methyl methanesulfonate (MMS) treatment. Exogenous expression of wild-type BRCA2, but not BRC-deleted mutants, in Capan-1 cells confers resistance to MMS treatment. These results suggest that the interaction between the BRC repeats of BRCA2 and RAD51 is critical for cellular response to DNA damage caused by MMS.

385 citations

Journal ArticleDOI
TL;DR: A link between GH signaling and translation control in a model of extended longevity is suggested and significantly less phosphorylation of 4E-BP1 was documented in dwarf liver.
Abstract: How growth hormone (GH) stimulates protein synthesis is unknown. Phosphoinositide 3-kinase/ Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathways balance anabolic and catabolic activities in response to nutrients and growth factor signaling. As a test of GH signaling, immunoassays of two downstream translation regulatory proteins were compared in ad libitum-fed 2-month-old normal and Ames (Prop1df) dwarf mice. Phosphorylation of the p70 and p85 isoforms of S6 kinase 1 in liver and the p70 isoform in gastrocnemius muscle were significantly decreased in dwarfs. Messenger RNA (mRNA) Cap-binding demonstrated significantly higher levels of translation repressor 4E-BPl/eukaryotic initiation factor 4E (eIF4E) (coprecipitates) from dwarf livers, but not muscle. Consistent with these binding data, significantly less phosphorylation of 4E-BP1 was documented in dwarf liver. These data suggest a link between GH signaling and translation control in a model of extended longevity.

134 citations


Cited by
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Journal ArticleDOI
06 Jun 2013-Cell
TL;DR: Nine tentative hallmarks that represent common denominators of aging in different organisms are enumerated, with special emphasis on mammalian aging, to identify pharmaceutical targets to improve human health during aging, with minimal side effects.

9,980 citations

01 Apr 2012
TL;DR: The mechanistic target of rapamycin (mTOR) signaling pathway senses and integrates a variety of environmental cues to regulate organismal growth and homeostasis as mentioned in this paper, and is implicated in an increasing number of pathological conditions, including cancer, obesity, type 2 diabetes, and neurodegeneration.
Abstract: The mechanistic target of rapamycin (mTOR) signaling pathway senses and integrates a variety of environmental cues to regulate organismal growth and homeostasis. The pathway regulates many major cellular processes and is implicated in an increasing number of pathological conditions, including cancer, obesity, type 2 diabetes, and neurodegeneration. Here, we review recent advances in our understanding of the mTOR pathway and its role in health, disease, and aging. We further discuss pharmacological approaches to treat human pathologies linked to mTOR deregulation.

6,268 citations

Journal ArticleDOI
13 Apr 2012-Cell
TL;DR: Recent advances in understanding of the mTOR pathway are reviewed and pharmacological approaches to treat human pathologies linked to mTOR deregulation are discussed.

5,792 citations

Journal ArticleDOI
09 Mar 2017-Cell
TL;DR: Recent advances in understanding of mTOR function, regulation, and importance in mammalian physiology are reviewed and how the mTOR signaling network contributes to human disease is highlighted.

4,719 citations

Journal ArticleDOI
TL;DR: It is clear now that degradation of cellular proteins is a highly complex, temporally controlled, and tightly regulated process that plays major roles in a variety of basic pathways during cell life and death as well as in health and disease.
Abstract: Between the 1960s and 1980s, most life scientists focused their attention on studies of nucleic acids and the translation of the coded information. Protein degradation was a neglected area, conside...

3,990 citations