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Specific inhibition of mTOR pathway induces anti-proliferative effect and decreases the hormone secretion in cultured pituitary adenoma cells. J Neurooncol 2015; 125:79-89. [DOI: 10.1007/s11060-015-1895-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Accepted: 08/14/2015] [Indexed: 02/02/2023]
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Xiong X, Xie R, Zhang H, Gu L, Xie W, Cheng M, Jian Z, Kovacina K, Zhao H. PRAS40 plays a pivotal role in protecting against stroke by linking the Akt and mTOR pathways. Neurobiol Dis 2014; 66:43-52. [PMID: 24583056 DOI: 10.1016/j.nbd.2014.02.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 01/08/2014] [Accepted: 02/19/2014] [Indexed: 11/16/2022] Open
Abstract
The proline-rich Akt substrate of 40kDa (PRAS40) protein is not only a substrate of the protein kinase Akt but also a component of the mTOR complex 1 (mTORC1), thus it links the Akt and the mTOR pathways. We investigated the potential protective role of PRAS40 in cerebral ischemia and its underlying mechanisms by using rats with lentiviral over-expression of PRAS40 and mice with PRAS40 gene knockout (PRAS40 KO). Our results show that gene transfer of PRAS40 reduced infarction size in rats by promoting phosphorylation of Akt, FKHR (FOXO1), PRAS40, and mTOR. In contrast, PRAS40 KO increased infarction size. Although the PRAS40 KO under normal condition did not alter baseline levels of phosphorylated proteins in the Akt and mTOR pathways, PRAS40 KO that underwent stroke exhibited reduced protein levels of p-S6K and p-S6 in the mTOR pathway but not p-Akt, or p-PTEN in the Akt pathway. Furthermore, co-immunoprecipitation suggests that there were less interactive effects between Akt and mTOR in the PRAS40 KO. In conclusion, PRAS40 appears to reduce brain injury by converting cell signaling from Akt to mTOR.
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Affiliation(s)
- Xiaoxing Xiong
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA
| | - Rong Xie
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA; Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Hongfei Zhang
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA
| | - Lijuan Gu
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA
| | - Weiying Xie
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA
| | - Michelle Cheng
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA
| | - Zhihong Jian
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA
| | - Kristina Kovacina
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Heng Zhao
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA.
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Lose dose genistein inhibits glucocorticoid receptor and ischemic brain injury in female rats. Neurochem Int 2014; 65:14-22. [DOI: 10.1016/j.neuint.2013.12.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 11/23/2013] [Accepted: 12/04/2013] [Indexed: 11/19/2022]
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Akt isoforms differentially protect against stroke-induced neuronal injury by regulating mTOR activities. J Cereb Blood Flow Metab 2013; 33:1875-85. [PMID: 23942361 PMCID: PMC3851893 DOI: 10.1038/jcbfm.2013.132] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 06/14/2013] [Accepted: 07/09/2013] [Indexed: 01/25/2023]
Abstract
Protein kinases Akt1 and Akt3 are considered to be more crucial to brain function than Akt2. We investigated the roles of Akt1 and Akt3 in stroke-induced brain injury and examined their interactions with the Akt/mTOR pathways. Focal ischemia was induced in rats. Lentiviral vectors expressing constitutively active Akt1 and Akt3 (cAkt1 and cAkt3) were injected into the ischemic cortex. Infarct sizes and gene and protein expressions in the Akt/mTOR pathways were evaluated. The results show that Akt1 and Akt3 proteins were degraded as early as 1 hour after stroke, whereas Akt2 proteins remained unchanged until 24 hours after stroke. Lentiviral-mediated overexpression of cAkt1 or cAkt3 reduced neuronal death after in vitro and in vivo ischemia. Interestingly, cAkt3 overexpression resulted in stronger protection than cAkt1 overexpression. Western blot analyses further showed that cAkt3 promoted significantly higher levels of phosphorylated Akt and phosphorylated mTOR than cAkt1. The mTOR inhibitor rapamycin blocked the protective effects of both cAkt1 and cAkt3. In conclusion, Akt isoforms are differentially regulated after stroke and Akt3 offers stronger protection than cAkt1 by maintaining Akt levels and promoting mTOR activity.
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Glucocorticoids and preterm hypoxic-ischemic brain injury: the good and the bad. J Pregnancy 2012; 2012:751694. [PMID: 22970371 PMCID: PMC3431094 DOI: 10.1155/2012/751694] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 07/13/2012] [Indexed: 12/20/2022] Open
Abstract
Fetuses at risk of premature delivery are now routinely exposed to maternal treatment with synthetic glucocorticoids. In randomized clinical trials, these substantially reduce acute neonatal systemic morbidity, and mortality, after premature birth and reduce intraventricular hemorrhage. However, the overall neurodevelopmental impact is surprisingly unclear; worryingly, postnatal glucocorticoids are consistently associated with impaired brain development. We review the clinical and experimental evidence on how glucocorticoids may affect the developing brain and highlight the need for systematic research.
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Whitehouse MW. Anti-inflammatory glucocorticoid drugs: reflections after 60 years. Inflammopharmacology 2010; 19:1-19. [PMID: 21072600 DOI: 10.1007/s10787-010-0056-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Accepted: 09/19/2010] [Indexed: 12/14/2022]
Abstract
This review considers the problem of the serious concomitant side effects of powerful anti-inflammatory drugs modelled upon the principal human glucocorticoid hormone, cortisol. The very nature of the original bio-assays to validate their cortisol-like hormonal and anti-inflammatory activities ensured that pleiotropic toxins were selected for clinical studies. Other complicating factors have been (1) considerable reliance on bio-assays conducted in laboratory animals that primarily secrete corticosterone, not cortisol, as their principal anti-inflammatory adrenal hormone; (2) some differences in the binding of xenobiotic cortisol analogues (vis á vis cortisol) to transport proteins, detoxifying enzymes and even some intra-cellular receptors; (3) the "rogue" properties of these hormonal xenobiotics, acting independently of--but still able to suppress--hormonal mechanisms regulating endogenous cortisol; and (4) problems of intrinsic/acquired "steroid resistance", diminishing their clinical efficacy, but not necessarily all their toxicities. The rather gloomy conclusion is that devising new drugs to reproduce the effect of multi-potent hormones may be a recipe for disaster, in contexts other than simply remedying an endocrine deficiency. Promising new developments include "designed" combination therapies that allow some reduction in total steroid doses (and hopefully their side effects); sharpening strategies to limit the actual duration of steroid administration; and resurgent interest in searching for more selective analogues (both steroidal and non-steroid) with less harmful side effects. Some oversights and neglected areas of research are also considered. Overall, it now seems timely to engage in some drastic rethinking about (retaining?) these "licensed toxins" as fundamental therapies for chronic inflammation.
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Siddiqui MA, Kashyap MP, Al-Khedhairy AA, Musarrat J, Khanna VK, Yadav S, Pant AB. Protective potential of 17β-estradiol against co-exposure of 4-hydroxynonenal and 6-hydroxydopamine in PC12 cells. Hum Exp Toxicol 2010; 30:860-9. [DOI: 10.1177/0960327110382130] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
4-hydroxynonenal (4-HNE) and 6-hydroxydopamine (6-OHDA)-mediated damage in dopaminergic neurons is well documented. Protective potential of steroidal hormone (17β-estradiol) has also been suggested. However, therapeutic potential of such promising hormone is hampered due to complex brain anatomy and physiology. Thus, the present investigations were studied to suggest the applicability of dopamine expressing PC12 cells as in vitro tool to screen the pharmacological potential of 17β-estradiol against 4-HNE and 6-OHDA. MTT assay was conducted for cytotoxicity assessment of both 4-HNE (1 μM to 50 μM) and 6-OHDA (10-4 to 10-7 M). Non-cytotoxic concentrations, that is, 4-HNE (1 μM) and 6-OHDA (10-6 M) were selected to study the synergetic/additive responses. PC12 cells were found to be more vulnerable towards co-exposure of individual exposure of 4-HNE and 6-OHDA, even at non-cytotoxic concentrations. Then, cells were subjected to pre-treatment (24 hours) of 17β-estradiol (1 μM), followed by a permutation of combinations of both 4-HNE and 6-OHDA. Pretreatment of 17β-estradiol was found to be significantly effective against the cytotoxic responses of 4-HNE and 6-OHDA, when the damage was at lower level. However, 17β-estradiol was found to be ineffective against higher concentrations. Physiological-specific responses of PC12 cells against 4-HNE/6-OHDA and 17β-estradiol suggest its applicability as first tier of screening tool.
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Affiliation(s)
- MA Siddiqui
- Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - MP Kashyap
- In Vitro Toxicology Laboratory, Indian Institute of Toxicology Research, Lucknow, India
| | - AA Al-Khedhairy
- Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - J. Musarrat
- Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - VK Khanna
- In Vitro Toxicology Laboratory, Indian Institute of Toxicology Research, Lucknow, India
| | - S. Yadav
- In Vitro Toxicology Laboratory, Indian Institute of Toxicology Research, Lucknow, India
| | - AB Pant
- In Vitro Toxicology Laboratory, Indian Institute of Toxicology Research, Lucknow, India,
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Craft TKS, Devries AC. Vulnerability to stroke: implications of perinatal programming of the hypothalamic-pituitary-adrenal axis. Front Behav Neurosci 2009; 3:54. [PMID: 20057937 PMCID: PMC2802556 DOI: 10.3389/neuro.08.054.2009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Accepted: 11/23/2009] [Indexed: 12/11/2022] Open
Abstract
Chronic stress is capable of exacerbating each major, modifiable, endogenous risk factor for cerebrovascular and cardiovascular disease. Indeed, exposure to stress can increase both the incidence and severity of stroke, presumably through activation of the hypothalamic-pituitary-adrenal (HPA) axis. Now that characterization of the mechanisms underlying epigenetic programming of the HPA axis is well underway, there has been renewed interest in examining the role of early environment on the evolution of health conditions across the entire lifespan. Indeed, neonatal manipulations in rodents that reduce stress responsivity, and subsequent life-time exposure to glucocorticoids, are associated with a reduction in the development of neuroendocrine, neuroanatomical, and cognitive dysfunctions that typically progress with age. Although improved day to day regulation of the HPA axis also may be accompanied by a decrease in stroke risk, evidence from rodent studies suggest that an associated cost could be increased susceptibility to inflammation and neuronal death in the event that a stroke does occur and the individual is exposed to persistently elevated corticosteroids. Given its importance in regulation of health and disease states, any long-term modulation of the HPA axis is likely to be associated with both benefits and potential risks. The goals of this review article are to examine (1) the clinical and experimental data suggesting that neonatal experiences can shape HPA axis regulation, (2) the influence of stress and the HPA axis on stroke incidence and severity, and (3) the potential for neonatal programming of the HPA axis to impact adult cerebrovascular health.
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Affiliation(s)
- Tara K S Craft
- Departments of Psychology, The Ohio State University Columbus, OH, USA
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