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Senftleben U, Cao Y, Xiao G, Greten FR, Krähn G, Bonizzi G, Chen Y, Hu Y, Fong A, Sun SC, Karin M. Activation by IKKalpha of a second, evolutionary conserved, NF-kappa B signaling pathway. Science 2001; 293:1495-9. [PMID: 11520989 DOI: 10.1126/science.1062677] [Citation(s) in RCA: 1073] [Impact Index Per Article: 44.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/18/2023]
Abstract
In mammals, the canonical nuclear factor kappaB (NF-kappaB) signaling pathway activated in response to infections is based on degradation of IkappaB inhibitors. This pathway depends on the IkappaB kinase (IKK), which contains two catalytic subunits, IKKalpha and IKKbeta. IKKbeta is essential for inducible IkappaB phosphorylation and degradation, whereas IKKalpha is not. Here we show that IKKalpha is required for B cell maturation, formation of secondary lymphoid organs, increased expression of certain NF-kappaB target genes, and processing of the NF-kappaB2 (p100) precursor. IKKalpha preferentially phosphorylates NF-kappaB2, and this activity requires its phosphorylation by upstream kinases, one of which may be NF-kappaB-inducing kinase (NIK). IKKalpha is therefore a pivotal component of a second NF-kappaB activation pathway based on regulated NF-kappaB2 processing rather than IkappaB degradation.
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Abstract
Apoptosis, a morphologically defined form of physiological cell death, is implemented by a death machinery whose executionary arm is a family of cysteine proteases called caspases. These death proteases are part of a proteolytic caspase cascade that is activated by diverse apoptotic stimuli from outside and inside of the cell. The cell death machinery is evolutionarily conserved and composed of caspases and their regulatory components that include activators and repressors. These key components of the death machinery are linked to signaling pathways that are activated by either ligation of death receptors expressed at the cell surface or intracellular death signals. Caspases are normally present in the cell as proenzymes that require limited proteolysis for activation of enzymatic activity. Recent studies suggest that the basic mechanism of caspase activation is conserved in evolution. Binding of initiator caspase precursors to activator molecules appears to promote procaspase oligomerization and autoactivation. Enzymatic activation of initiator caspases leads to proteolytic activation of downstream (effector) caspases and cleavage of a number of vital proteins, resulting in the orderly demise and removal of the cell.
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Review |
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Li ZW, Chu W, Hu Y, Delhase M, Deerinck T, Ellisman M, Johnson R, Karin M. The IKKbeta subunit of IkappaB kinase (IKK) is essential for nuclear factor kappaB activation and prevention of apoptosis. J Exp Med 1999; 189:1839-45. [PMID: 10359587 PMCID: PMC2193082 DOI: 10.1084/jem.189.11.1839] [Citation(s) in RCA: 753] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/25/2022] Open
Abstract
The IkappaB kinase (IKK) complex is composed of three subunits, IKKalpha, IKKbeta, and IKKgamma (NEMO). While IKKalpha and IKKbeta are highly similar catalytic subunits, both capable of IkappaB phosphorylation in vitro, IKKgamma is a regulatory subunit. Previous biochemical and genetic analyses have indicated that despite their similar structures and in vitro kinase activities, IKKalpha and IKKbeta have distinct functions. Surprisingly, disruption of the Ikkalpha locus did not abolish activation of IKK by proinflammatory stimuli and resulted in only a small decrease in nuclear factor (NF)-kappaB activation. Now we describe the pathophysiological consequence of disruption of the Ikkbeta locus. IKKbeta-deficient mice die at mid-gestation from uncontrolled liver apoptosis, a phenotype that is remarkably similar to that of mice deficient in both the RelA (p65) and NF-kappaB1 (p50/p105) subunits of NF-kappaB. Accordingly, IKKbeta-deficient cells are defective in activation of IKK and NF-kappaB in response to either tumor necrosis factor alpha or interleukin 1. Thus IKKbeta, but not IKKalpha, plays the major role in IKK activation and induction of NF-kappaB activity. In the absence of IKKbeta, IKKalpha is unresponsive to IKK activators.
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Hu Y, Baud V, Delhase M, Zhang P, Deerinck T, Ellisman M, Johnson R, Karin M. Abnormal morphogenesis but intact IKK activation in mice lacking the IKKalpha subunit of IkappaB kinase. Science 1999; 284:316-20. [PMID: 10195896 DOI: 10.1126/science.284.5412.316] [Citation(s) in RCA: 664] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/02/2022]
Abstract
The oligomeric IkappaB kinase (IKK) is composed of three polypeptides: IKKalpha and IKKbeta, the catalytic subunits, and IKKgamma, a regulatory subunit. IKKalpha and IKKbeta are similar in structure and thought to have similar function-phosphorylation of the IkappaB inhibitors in response to proinflammatory stimuli. Such phosphorylation leads to degradation of IkappaB and activation of nuclear factor kappaB transcription factors. The physiological function of these protein kinases was explored by analysis of IKKalpha-deficient mice. IKKalpha was not required for activation of IKK and degradation of IkappaB by proinflammatory stimuli. Instead, loss of IKKalpha interfered with multiple morphogenetic events, including limb and skeletal patterning and proliferation and differentiation of epidermal keratinocytes.
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Wei Z, Wang D, Kim S, Kim SY, Hu Y, Yakes MK, Laracuente AR, Dai Z, Marder SR, Berger C, King WP, de Heer WA, Sheehan PE, Riedo E. Nanoscale Tunable Reduction of Graphene Oxide for Graphene Electronics. Science 2010; 328:1373-6. [DOI: 10.1126/science.1188119] [Citation(s) in RCA: 601] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/02/2022]
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Inohara N, Koseki T, del Peso L, Hu Y, Yee C, Chen S, Carrio R, Merino J, Liu D, Ni J, Núñez G. Nod1, an Apaf-1-like activator of caspase-9 and nuclear factor-kappaB. J Biol Chem 1999; 274:14560-7. [PMID: 10329646 DOI: 10.1074/jbc.274.21.14560] [Citation(s) in RCA: 550] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/06/2022] Open
Abstract
Ced-4 and Apaf-1 belong to a major class of apoptosis regulators that contain caspase-recruitment (CARD) and nucleotide-binding oligomerization domains. Nod1, a protein with an NH2-terminal CARD-linked to a nucleotide-binding domain and a COOH-terminal segment with multiple leucine-rich repeats, was identified. Nod-1 was found to bind to multiple caspases with long prodomains, but specifically activated caspase-9 and promoted caspase-9-induced apoptosis. As reported for Apaf-1, Nod1 required both the CARD and P-loop for function. Unlike Apaf-1, Nod1 induced activation of nuclear factor-kappa-B (NF-kappaB) and bound RICK, a CARD-containing kinase that also induces NF-kappaB activation. Nod1 mutants inhibited NF-kappaB activity induced by RICK, but not that resulting from tumor necrosis factor-alpha stimulation. Thus, Nod1 is a leucine-rich repeat-containing Apaf-1-like molecule that can regulate both apoptosis and NF-kappaB activation pathways.
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Rampon C, Jiang CH, Dong H, Tang YP, Lockhart DJ, Schultz PG, Tsien JZ, Hu Y. Effects of environmental enrichment on gene expression in the brain. Proc Natl Acad Sci U S A 2000; 97:12880-4. [PMID: 11070096 PMCID: PMC18858 DOI: 10.1073/pnas.97.23.12880] [Citation(s) in RCA: 448] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/18/2022] Open
Abstract
An enriched environment is known to promote structural changes in the brain and to enhance learning and memory performance in rodents [Hebb, D. O. (1947) Am. Psychol. 2, 306-307]. To better understand the molecular mechanisms underlying these experience-dependent cognitive changes, we have used high-density oligonucleotide microarrays to analyze gene expression in the brain. Expression of a large number of genes changes in response to enrichment training, many of which can be linked to neuronal structure, synaptic plasticity, and transmission. A number of these genes may play important roles in modulating learning and memory capacity.
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Hu Y, Benedict MA, Wu D, Inohara N, Núñez G. Bcl-XL interacts with Apaf-1 and inhibits Apaf-1-dependent caspase-9 activation. Proc Natl Acad Sci U S A 1998; 95:4386-91. [PMID: 9539746 PMCID: PMC22498 DOI: 10.1073/pnas.95.8.4386] [Citation(s) in RCA: 397] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 02/07/2023] Open
Abstract
Recent studies indicate that Caenorhabditis elegans CED-4 interacts with and promotes the activation of the death protease CED-3, and that this activation is inhibited by CED-9. Here we show that a mammalian homolog of CED-4, Apaf-1, can associate with several death proteases, including caspase-4, caspase-8, caspase-9, and nematode CED-3 in mammalian cells. The interaction with caspase-9 was mediated by the N-terminal CED-4-like domain of Apaf-1. Expression of Apaf-1 enhanced the killing activity of caspase-9 that required the CED-4-like domain of Apaf-1. Furthermore, Apaf-1 promoted the processing and activation of caspase-9 in vivo. Bcl-XL, an antiapoptotic member of the Bcl-2 family, was shown to physically interact with Apaf-1 and caspase-9 in mammalian cells. The association of Apaf-1 with Bcl-XL was mediated through both its CED-4-like domain and the C-terminal domain containing WD-40 repeats. Expression of Bcl-XL inhibited the association of Apaf-1 with caspase-9 in mammalian cells. Significantly, recombinant Bcl-XL purified from Escherichia coli or insect cells inhibited Apaf-1-dependent processing of caspase-9. Furthermore, Bcl-XL failed to inhibit caspase-9 processing mediated by a constitutively active Apaf-1 mutant, suggesting that Bcl-XL regulates caspase-9 through Apaf-1. These experiments demonstrate that Bcl-XL associates with caspase-9 and Apaf-1, and show that Bcl-XL inhibits the maturation of caspase-9 mediated by Apaf-1, a process that is evolutionarily conserved from nematodes to humans.
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Zhuo M, Hu Y, Schultz C, Kandel ER, Hawkins RD. Role of guanylyl cyclase and cGMP-dependent protein kinase in long-term potentiation. Nature 1994; 368:635-9. [PMID: 7908417 DOI: 10.1038/368635a0] [Citation(s) in RCA: 366] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/27/2023]
Abstract
Several lines of evidence suggest that cyclic GMP might be involved in long-term potentiation (LTP) in the hippocampus. Arachidonic acid, nitric oxide and carbon monoxide, three molecules that have been proposed to act as retrograde messengers in LTP, all activate soluble guanylyl cyclase. We report here that an inhibitor of guanylyl cyclase blocks the induction of LTP in the CA1 region of hippocampal slices. Conversely, cGMP analogues produce long-lasting enhancement of the excitatory postsynaptic potential if they are applied at the same time as weak tetanic stimulation of the presynaptic fibres. The enhancement is spatially restricted, is not blocked by valeric acid (APV), nifedipine, or picrotoxin, and partially occludes LTP. This synaptic enhancement may be mediated by the cGMP-dependent protein kinase (PKG). Inhibitors of PKG block the induction of LTP, and activators of PKG produce activity-dependent long-lasting enhancement. These results suggest that guanylyl cyclase and PKG contribute to LTP, possibly as activity-dependent presynaptic effectors of retrograde messengers.
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Hu Y, Benedict MA, Ding L, Núñez G. Role of cytochrome c and dATP/ATP hydrolysis in Apaf-1-mediated caspase-9 activation and apoptosis. EMBO J 1999; 18:3586-95. [PMID: 10393175 PMCID: PMC1171437 DOI: 10.1093/emboj/18.13.3586] [Citation(s) in RCA: 354] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/13/2022] Open
Abstract
Apaf-1 plays a critical role in apoptosis by binding to and activating procaspase-9. We have identified a novel Apaf-1 cDNA encoding a protein of 1248 amino acids containing an insertion of 11 residues between the CARD and ATPase domains, and another 43 amino acid insertion creating an additional WD-40 repeat. The product of this Apaf-1 cDNA activated procaspase-9 in a cytochrome c and dATP/ATP-dependent manner. We used this Apaf-1 to show that Apaf-1 requires dATP/ATP hydrolysis to interact with cytochrome c, self-associate and bind to procaspase-9. A P-loop mutant (Apaf-1K160R) was unable to associate with Apaf-1 or bind to procaspase-9. Mutation of Met368 to Leu enabled Apaf-1 to self-associate and bind procaspase-9 independent of cytochrome c, though still requiring dATP/ATP for these activities. The Apaf-1M368L mutant exhibited greater ability to induce apoptosis compared with the wild-type Apaf-1. We also show that procaspase-9 can recruit procaspase-3 to the Apaf-1-procaspase-9 complex. Apaf-1(1-570), a mutant lacking the WD-40 repeats, associated with and activated procaspase-9, but failed to recruit procaspase-3 and induce apoptosis. These results suggest that the WD-40 repeats may be involved in procaspase-9-mediated procaspase-3 recruitment. These studies elucidate biochemical steps required for Apaf-1 to activate procaspase-9 and induce apoptosis.
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Liu J, Stevens J, Rote CA, Yost HJ, Hu Y, Neufeld KL, White RL, Matsunami N. Siah-1 mediates a novel beta-catenin degradation pathway linking p53 to the adenomatous polyposis coli protein. Mol Cell 2001; 7:927-36. [PMID: 11389840 DOI: 10.1016/s1097-2765(01)00241-6] [Citation(s) in RCA: 333] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/27/2023]
Abstract
The adenomatous polyposis coli (APC) tumor-suppressor protein, together with Axin and GSK3beta, forms a Wnt-regulated signaling complex that mediates phosphorylation-dependent degradation of beta-catenin by the proteasome. Siah-1, the human homolog of Drosophila seven in absentia, is a p53-inducible mediator of cell cycle arrest, tumor suppression, and apoptosis. We have now found that Siah-1 interacts with the carboxyl terminus of APC and promotes degradation of beta-catenin in mammalian cells. The ability of Siah-1 to downregulate beta-catenin signaling was also demonstrated by hypodorsalization of Xenopus embryos. Unexpectedly, degradation of beta-catenin by Siah-1 was independent of GSK3beta-mediated phosphorylation and did not require the F box protein beta-TrCP. These results indicate that APC and Siah-1 mediate a novel beta-catenin degradation pathway linking p53 activation to cell cycle control.
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Chu WM, Ostertag D, Li ZW, Chang L, Chen Y, Hu Y, Williams B, Perrault J, Karin M. JNK2 and IKKbeta are required for activating the innate response to viral infection. Immunity 1999; 11:721-31. [PMID: 10626894 DOI: 10.1016/s1074-7613(00)80146-6] [Citation(s) in RCA: 325] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 12/17/2022]
Abstract
Viral infection or double-stranded (ds) RNA induce interferons (IFN) and other cytokines. Transcription factors mediating IFN induction are known, but the signaling pathways that regulate them are less clear. We now describe two such pathways. The first pathway leading to NF-kappaB depends on the dsRNA-responsive protein kinase (PKR), which in turn activates IKB kinase (IKK) through the IKKbeta subunit. The second viral-and dsRNA-responsive pathway is PKR independent and involves Jun kinase (JNK) activation leading to stimulation of AP-1. Both IKKbeta and JNK2 are essential for efficient induction of type I IFN and other cytokines in response to viral infection or dsRNA. This study establishes a general role for these kinases in activation of innate immune responses.
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Hu Y, Baud V, Oga T, Kim KI, Yoshida K, Karin M. IKKalpha controls formation of the epidermis independently of NF-kappaB. Nature 2001; 410:710-4. [PMID: 11287960 DOI: 10.1038/35070605] [Citation(s) in RCA: 294] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/11/2023]
Abstract
The IKKalpha and IKKbeta catalytic subunits of IkappaB kinase (IKK) share 51% amino-acid identity and similar biochemical activities: they both phosphorylate IkappaB proteins at serines that trigger their degradation. IKKalpha and IKKbeta differ, however, in their physiological functions. IKKbeta and the IKKgamma/NEMO regulatory subunit are required for activating NF-kappaB by pro-inflammatory stimuli and preventing apoptosis induced by tumour necrosis factor-alpha (refs 5,6,7,8,9,10,11). IKKalpha is dispensable for these functions, but is essential for developing the epidermis and its derivatives. The mammalian epidermis is composed of the basal, spinous, granular and cornified layers. Only basal keratinocytes can proliferate and give rise to differentiated derivatives, which on full maturation undergo enucleation to generate the cornified layer. Curiously, keratinocyte-specific inhibition of NF-kappaB, as in Ikkalpha-/- mice, results in epidermal thickening but does not block terminal differentiation. It has been proposed that the epidermal defect in Ikkalpha-/- mice may be due to the failed activation of NF-kappaB. Here we show that the unique function of IKKalpha in control of keratinocyte differentiation is not exerted through its IkappaB kinase activity or through NF-kappaB. Instead, IKKalpha controls production of a soluble factor that induces keratinocyte differentiation.
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Drossman DA, Patrick DL, Whitehead WE, Toner BB, Diamant NE, Hu Y, Jia H, Bangdiwala SI. Further validation of the IBS-QOL: a disease-specific quality-of-life questionnaire. Am J Gastroenterol 2000; 95:999-1007. [PMID: 10763950 DOI: 10.1111/j.1572-0241.2000.01941.x] [Citation(s) in RCA: 293] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE There has been growing interest in the investigation of health-related quality of life (HRQOL) among patients with gastrointestinal (GI) disorders. We recently reported on the development and preliminary validation of the IBS-QOL, a specific quality-of-life measure for irritable bowel syndrome (IBS). The aim of this study was to determine the longitudinal construct validity (responsiveness) of the IBS-QOL. METHODS Female patients enrolled in a multicenter treatment trial for functional bowel disorders were studied pre- and posttreatment with the IBS-QOL and other health status measures. Based on the response to treatment for several variables (pain/14-day score, daily function, and days in bed/3 months), patients were stratified into Responders, Partial Responders, and Nonresponders. Change scores in the IBS-QOL were then statistically compared with changes in the other variables to determine their correlation and whether Responders were significantly different from non- and Partial Responders on the IBS-QOL. RESULTS There was a significant correlation between change scores on the IBS-QOL and the other measures of treatment effect (Pain/14 days, r = 0.25, p < 0.002; Sickness Impact Profile [SIP] Total Score, r = 0.28, p < 0.0004). In addition, the IBS-QOL scores significantly differentiated Responders from Nonresponders for most of the variables tested (regression trend test for Pain/14 days, p < 0.04; SIP Total, p < 0.0001; SIP Physical, p < 0.0001; SIP Psychosocial, p < 0.002, and SIP Eating, p < 0.04). CONCLUSION The IBS-QOL is responsive to treatment in a referral-based clinical population of patients with functional bowel disorders.
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Clinical Trial |
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Tsai KY, Hu Y, Macleod KF, Crowley D, Yamasaki L, Jacks T. Mutation of E2f-1 suppresses apoptosis and inappropriate S phase entry and extends survival of Rb-deficient mouse embryos. Mol Cell 1998; 2:293-304. [PMID: 9774968 DOI: 10.1016/s1097-2765(00)80274-9] [Citation(s) in RCA: 276] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 10/26/2022]
Abstract
Mice mutant for the Rb tumor suppressor gene die in mid-gestation with defects in erythropoiesis, cell cycle control, and apoptosis. We show here that embryos mutant for both Rb and its downstream target E2f-1 demonstrate significant suppression of apoptosis and S phase entry in certain tissues compared to Rb mutants, implicating E2f-1 as a critical mediator of these effects. Up-regulation of the p53 pathway, required for cell death in these cells in Rb mutants, is also suppressed in the Rb/E2f-1 double mutants. However, double mutants have defects in cell cycle regulation and apoptosis in some tissues and die at approximately E17.0 with anemia and defective skeletal muscle and lung development, demonstrating that E2F-1 regulation is not the sole function of pRB in development.
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Xi B, Liang Y, He T, Reilly KH, Hu Y, Wang Q, Yan Y, Mi J. Secular trends in the prevalence of general and abdominal obesity among Chinese adults, 1993-2009. Obes Rev 2012; 13:287-96. [PMID: 22034908 PMCID: PMC3276709 DOI: 10.1111/j.1467-789x.2011.00944.x] [Citation(s) in RCA: 276] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Indexed: 12/31/2022]
Abstract
The objective of this study is to examine the trends in body mass index (BMI), waist circumference (WC) and prevalence of overweight (BMI 25-27.49 kg m(-2) ), general obesity (BMI ≥ 27.5 kg m(-2) ) and abdominal obesity (WC ≥ 90 cm for men and ≥80 cm for women) among Chinese adults from 1993 to 2009. Data were obtained from the China Health and Nutrition Survey, which was conducted from 1993 to 2009 and included a total of 52,621 Chinese adults. During the period of 1993-2009, mean BMI values increased by 1.6 kg m(-2) among men and 0.8 kg m(-2) among women; mean WC values increased by 7.0 cm among men and 4.7 cm among women. The prevalence of overweight increased from 8.0 to 17.1% among men (P < 0.001) and from 10.7 to 14.4% among women (P < 0.001); the prevalence of general obesity increased from 2.9 to 11.4% among men (P < 0.001) and from 5.0 to 10.1% among women (P < 0.001); the prevalence of abdominal obesity increased from 8.5 to 27.8% among men (P < 0.001) and from 27.8 to 45.9% among women (P < 0.001). Similar significant trends were observed in nearly all age groups and regions for both men and women. The prevalence of overweight, general obesity and abdominal obesity among Chinese adults has increased greatly during the past 17 years.
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Research Support, N.I.H., Extramural |
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Jones CM, Henry ER, Hu Y, Chan CK, Luck SD, Bhuyan A, Roder H, Hofrichter J, Eaton WA. Fast events in protein folding initiated by nanosecond laser photolysis. Proc Natl Acad Sci U S A 1993; 90:11860-4. [PMID: 8265638 PMCID: PMC48084 DOI: 10.1073/pnas.90.24.11860] [Citation(s) in RCA: 261] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/29/2023] Open
Abstract
Initiation of protein folding by light can dramatically improve the time resolution of kinetic studies. Here we present an example of an optically triggered folding reaction by using nanosecond photodissociation of the heme-carbon monoxide complex of reduced cytochrome c. The optical trigger is based on the observation that under destabilizing conditions cytochrome c can be unfolded by preferential binding of carbon monoxide to the covalently attached heme group in the unfolded state. Photodissociation of the carbon monoxide thus triggers the folding reaction. We used time-resolved absorption spectroscopy to monitor binding at the heme. Before folding begins we observe transient binding of both nonnative and native ligands from the unfolded polypeptide on a microsecond time scale. Kinetic modeling suggests that the intramolecular binding of methionine-65 and -80 is faster than that of histidine-26 and -33, even though the histidines are closer to the heme. This optical trigger should provide a powerful method for studying chain collapse and secondary structure formation in cytochrome c without any limitations in time resolution.
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Dunbar JC, Hu Y, Lu H. Intracerebroventricular leptin increases lumbar and renal sympathetic nerve activity and blood pressure in normal rats. Diabetes 1997; 46:2040-3. [PMID: 9392493 DOI: 10.2337/diab.46.12.2040] [Citation(s) in RCA: 258] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Indexed: 02/05/2023]
Abstract
Obesity and hyperinsulinism are known to be major stimuli of leptin production by adipose tissue, leading to increased leptin levels in the circulation. It has also been demonstrated that increased leptin production leads to satiety, possibly by decreasing the levels of neuropeptide Y (NPY) in the central nervous system (CNS). Because obesity and hyperinsulinism are also frequently associated with hypertension, we studied the effect of the intracerebroventricular (ICV) administration of leptin on mean arterial pressure (MAP), heart rate, vascular flows, and lumbar and renal sympathetic nerve activity (SNA). Normal Wistar rats were implanted with an ICV cannula and allowed to recover. On the day of the study, the animals were fasted and anesthetized with chloralose/urethane. Catheters were placed in a femoral artery and vein, and Doppler flow probes were placed around the iliac, renal, and superior mesenteric arteries for measurement of MAP, heart rate, and blood flows. In other experiments, lumbar SNA and renal SNA were recorded. ICV leptin administration resulted in an MAP that was slowly but progressively increasing. Blood flows decreased in the iliac and superior mesenteric arteries, but not in the renal artery. Leptin injection increased the lumbar SNA and renal SNA. The plasma glucose and insulin levels were not changed. We concluded that ICV leptin increases MAP by decreasing arterial blood flow to the skeletal muscle and the splanchnic vascular bed. This increased peripheral resistance is the result of an increased activity of the sympathetic nerves. We suggest that increased leptin may serve as a link in the triad of obesity and hyperinsulinism and hypertension.
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Sabapathy K, Hu Y, Kallunki T, Schreiber M, David JP, Jochum W, Wagner EF, Karin M. JNK2 is required for efficient T-cell activation and apoptosis but not for normal lymphocyte development. Curr Biol 1999; 9:116-25. [PMID: 10021384 DOI: 10.1016/s0960-9822(99)80065-7] [Citation(s) in RCA: 252] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND The Jun N-terminal kinase (JNK) signaling pathway has been implicated in cell proliferation and apoptosis, but its function seems to depend on the cell type and inducing signal. In T cells, JNK has been implicated in both antigen-induced activation and apoptosis. RESULTS We generated mice lacking the JNK2 isozymes. The mutant mice were healthy and fertile but defective in peripheral T-cell activation induced by antibody to the CD3 component of the T-cell receptor (TCR) complex - proliferation and production of interleukin-2 (IL-2), IL-4 and interferon-gamma (IFN-gamma) were reduced. The proliferation defect was restored by exogenous IL-2. B-cell activation was normal in the absence of JNK2. Activation-induced peripheral T-cell apoptosis was comparable between mutant and wild-type mice, but immature (CD4(+) CD8(+)) thymocytes lacking JNK2 were resistant to apoptosis induced by administration of anti-CD3 antibody in vivo. The lack of JNK2 also resulted in partial resistance of thymocytes to anti-CD3 antibody in vitro, but had little or no effect on apoptosis induced by anti-Fas antibody, dexamethasone or ultraviolet-C (UVC) radiation. CONCLUSIONS JNK2 is essential for efficient activation of peripheral T cells but not B cells. Peripheral T-cell activation is probably required indirectly for induction of thymocyte apoptosis resulting from administration of anti-CD3 antibody in vivo. JNK2 functions in a cell-type-specific and stimulus-dependent manner, being required for apoptosis of immature thymocytes induced by anti-CD3 antibody but not for apoptosis induced by anti-Fas antibody, UVC or dexamethasone. JNK2 is not required for activation-induced cell death of mature T cells.
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Li X, Du N, Zhang Q, Li J, Chen X, Liu X, Hu Y, Qin W, Shen N, Xu C, Fang Z, Wei Y, Wang R, Du Z, Zhang Y, Lu Y. MicroRNA-30d regulates cardiomyocyte pyroptosis by directly targeting foxo3a in diabetic cardiomyopathy. Cell Death Dis 2014; 5:e1479. [PMID: 25341033 PMCID: PMC4237254 DOI: 10.1038/cddis.2014.430] [Citation(s) in RCA: 251] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 06/22/2014] [Revised: 08/27/2014] [Accepted: 09/04/2014] [Indexed: 12/15/2022]
Abstract
Diabetic cardiomyopathy is a common cardiac condition in patients with diabetes mellitus, which can result in cardiac hypertrophy and subsequent heart failure, associated with pyroptosis, the pro-inflammatory programmed cell death. MicroRNAs (miRNAs), small endogenous non-coding RNAs, have been shown to be involved in diabetic cardiomyopathy. However, whether miRNAs regulate pyroptosis in diabetic cardiomyopathy remains unknown. Our study revealed that mir-30d expression was substantially increased in streptozotocin (STZ)-induced diabetic rats and in high-glucose-treated cardiomyocytes as well. Upregulation of mir-30d promoted cardiomyocyte pyroptosis in diabetic cardiomyopathy; conversely, knockdown of mir-30d attenuated it. In an effort to understand the signaling mechanisms underlying the pro-pyroptotic property of mir-30d, we found that forced expression of mir-30d upregulated caspase-1 and pro-inflammatory cytokines IL-1β and IL-18. Moreover, mir-30d directly repressed foxo3a expression and its downstream protein, apoptosis repressor with caspase recruitment domain (ARC). Furthermore, silencing ARC by siRNA mimicked the action of mir-30d: upregulating caspase-1 and inducing pyroptosis. These findings promoted us to propose a new signaling pathway leading to cardiomyocyte pyroptosis under hyperglycemic conditions: mir-30d↑→foxo3a↓→ ARC↓→caspase-1↑→IL-1β, IL-18↑→pyroptosis↑. Therefore, mir-30d may be a promising therapeutic target for the management of diabetic cardiomyopathy.
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Research Support, Non-U.S. Gov't |
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Jiang CH, Tsien JZ, Schultz PG, Hu Y. The effects of aging on gene expression in the hypothalamus and cortex of mice. Proc Natl Acad Sci U S A 2001; 98:1930-4. [PMID: 11172053 PMCID: PMC29359 DOI: 10.1073/pnas.98.4.1930] [Citation(s) in RCA: 239] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/18/2022] Open
Abstract
A better understanding of the molecular effects of aging in the brain may help to reveal important aspects of organismal aging, as well as processes that lead to age-related brain dysfunction. In this study, we have examined differences in gene expression in the hypothalamus and cortex of young and aged mice by using high-density oligonucleotide arrays. A number of key genes involved in neuronal structure and signaling are differentially expressed in both the aged hypothalamus and cortex, including synaptotagmin I, cAMP-dependent protein kinase C beta, apolipoprotein E, protein phosphatase 2A, and prostaglandin D. Misregulation of these proteins may contribute to age-related memory deficits and neurodegenerative diseases. In addition, many proteases that play essential roles in regulating neuropeptide metabolism, amyloid precursor protein processing, and neuronal apoptosis are up-regulated in the aged brain and likely contribute significantly to brain aging. Finally, a subset of these genes whose expression is affected by aging are oppositely affected by exposure of mice to an enriched environment, suggesting that these genes may play important roles in learning and memory.
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Macleod KF, Hu Y, Jacks T. Loss of Rb activates both p53-dependent and independent cell death pathways in the developing mouse nervous system. EMBO J 1996. [DOI: 10.1002/j.1460-2075.1996.tb01006.x] [Citation(s) in RCA: 237] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/07/2022] Open
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Liu WJ, Zhu YG, Hu Y, Williams PN, Gault AG, Meharg AA, Charnock JM, Smith FA. Arsenic sequestration in iron plaque, its accumulation and speciation in mature rice plants (Oryza sativa L.). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2006; 40:5730-6. [PMID: 17007133 DOI: 10.1021/es060800v] [Citation(s) in RCA: 236] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Academic Contribution Register] [Indexed: 05/12/2023]
Abstract
A compartmented soil-glass bead culture system was used to investigate characteristics of iron plaque and arsenic accumulation and speciation in mature rice plants with different capacities of forming iron plaque on their roots. X-ray absorption near-edge structure spectra and extended X-ray absorption fine structure were utilized to identify the mineralogical characteristics of iron plaque and arsenic sequestration in plaque on the rice roots. Iron plaque was dominated by (oxyhydr)oxides, which were composed of ferrihydrite (81-100%), with a minor amount of goethite (19%) fitted in one of the samples. Sequential extraction and XANES data showed that arsenic in iron plaque was sequestered mainly with amorphous and crystalline iron (oxyhydr)oxides, and that arsenate was the predominant species. There was significant variation in iron plaque formation between genotypes, and the distribution of arsenic in different components of mature rice plants followed the following order: iron plaque > root > straw > husk > grain for all genotypes. Arsenic accumulation in grain differed significantly among genotypes. Inorganic arsenic and dimethylarsinic acid (DMA) were the main arsenic species in rice grain for six genotypes, and there were large genotypic differences in levels of DMA and inorganic arsenic in grain.
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Tian Z, Li L, Wang L, Hu Y, Li J. Salivary gland neoplasms in oral and maxillofacial regions: a 23-year retrospective study of 6982 cases in an eastern Chinese population. Int J Oral Maxillofac Surg 2009; 39:235-42. [PMID: 19951834 DOI: 10.1016/j.ijom.2009.10.016] [Citation(s) in RCA: 234] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 01/09/2009] [Revised: 07/06/2009] [Accepted: 10/27/2009] [Indexed: 12/13/2022]
Abstract
There is little information in the English-language literature about the epidemiology of salivary gland neoplasms in the eastern Chinese population. A large retrospective study (6982 primary salivary tumors during 23 years) was carried out to investigate the clinicopathological features (tumor location, patient sex and age) of these tumors in this population. 3593 tumors were in males and 3389 in females. Pleomorphic adenoma (69%) was the most common tumor and 20% were located in minor glands. 92% of Warthin's tumors occurred in males. Malignant tumors were predominantly adenoid cystic carcinoma (30%) and mucoepidermoid carcinoma (30%). Incidences of lymphoepithelial carcinomas (5%) and polymorphous low-grade adenocarcinoma (1%) of malignant tumors were identified. 28% of tumors originated from minor glands. Most findings were similar to those in the literature, with some variations. The salivary tumors slightly predominated in males. Relatively higher incidences of minor gland tumors and specifically of pleomorphic adenoma in minor glands were noted. Adenoid cystic carcinoma and mucoepidermoid carcinoma constituted the most common malignancies. There was a high incidence of lymphoepithelial carcinomas but a low incidence of polymorphous low-grade adenocarcinoma. The historical significant male predominance of Warthin's tumor was confirmed.
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Research Support, Non-U.S. Gov't |
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