Search PubMed⌕ Search

Biomedical subjects

Kun Zou

Publications and source records attributed to Kun Zou.

At least 19 recordsLinked to original sources
PubMed2025

GATA2 promotes cervical cancer progression under the transcriptional activation of TRIP4.

The continued rise in recurrence and mortality rates of cervical cancer suggests the need to find novel therapeutic targets. Previous studies suggest that TRIP4 acts as a transcription factor to regulate cervical carcinogenesis and progression. Our aim was to explore whether the key downstream genes of TRIP4 functions same as TRIP4 in promoting cervical cancer development. We analyzed and confirmed the downstream targets of TRIP4 by RNA sequencing in cervical cancer cells with TRIP4 knockdown. The expression correlation between TRIP4 and GATA2 and the effect of GATA2 on cervical cancer cell growth were determined respectively by Western Blot, Scratch, Spheroid, and MTT analyses. Pulldown and ChIP experiments were performed to analyze the binding of TRIP4 to the promoter of GATA2. The clinical significance of GATA2 and TRIP4 expression in cervical cancer patients was analyzed by tissue microarray staining. GATA2 was highly expressed in cervical cancer tissues. Knockdown of GATA2 inhibited the growth, metastasis and stemness of cervical cancer cells and sensitized cervical cancer cells to radiation therapy. The inhibitory effect of TRIP4 knockdown on cervical cancer cells was rescued by GATA2 overexpression. Furthermore, TRIP4 could bind to the specific GATA2 promoter region, thereby activating its transcription. Clinical tissue microarray analysis indicated that the expression of TRIP4 and GATA2 was positively correlated, and high expression of both predicted a poor prognosis in cervical cancer patients. Our study demonstrated that GATA2 functions as the key downstream target of TRIP4 to promote cervical cancer progression and effective intervention of TRIP4/GATA2 signaling is expected to be developed as potential cervical cancer therapeutic strategy.

Humans↗
PubMed2006

Highly sensitive and specific bioassay for measuring bioactive TGF-beta.

BACKGROUND: Transforming Growth Factor-beta (TGF-beta) regulates key biological processes during development and in adult tissues and has been implicated in many diseases. To study the biological functions of TGF-beta, sensitive, specific, and convenient bioassays are necessary. Here we describe a new cell-based bioassay that fulfills these requirements. RESULTS: Embryonic fibroblasts from Tgfb1-/- mice were stably transfected with a reporter plasmid consisting of TGF-beta responsive Smad-binding elements coupled to a secreted alkaline phosphatase reporter gene (SBE-SEAP). Clone MFB-F11 showed more than 1000-fold induction after stimulation with 1 ng/ml TGF-beta1, and detected as little as 1 pg/ml TGF-beta1. MFB-F11 cells were highly induced by TGF-beta1, TGF-beta2 and TGF-beta3, but did not show induction with related family members activin, nodal, BMP-2 and BMP-6 or with trophic factors bFGF and BDNF. MFB-F11 cells can detect and quantify TGF-beta in biological samples without prior enrichment of TGF-betas, and can detect biologically activated TGF-beta in a cell co-culture system. CONCLUSION: MFB-F11 cells can be used to rapidly and specifically measure TGF-beta with high sensitivity.

Alkaline Phosphatase↗
PubMed2006

Deficiency in neuronal TGF-beta signaling promotes neurodegeneration and Alzheimer's pathology.

Alzheimer's disease (AD) is characterized by progressive neurodegeneration and cerebral accumulation of the beta-amyloid peptide (Abeta), but it is unknown what makes neurons susceptible to degeneration. We report that the TGF-beta type II receptor (TbetaRII) is mainly expressed by neurons, and that TbetaRII levels are reduced in human AD brain and correlate with pathological hallmarks of the disease. Reducing neuronal TGF-beta signaling in mice resulted in age-dependent neurodegeneration and promoted Abeta accumulation and dendritic loss in a mouse model of AD. In cultured cells, reduced TGF-beta signaling caused neuronal degeneration and resulted in increased levels of secreted Abeta and beta-secretase-cleaved soluble amyloid precursor protein. These results show that reduced neuronal TGF-beta signaling increases age-dependent neurodegeneration and AD-like disease in vivo. Increasing neuronal TGF-beta signaling may thus reduce neurodegeneration and be beneficial in AD.

Aging↗
PubMed2006

A cytotoxic saponin from Albizia julibrissin.

A new triterpenoidal saponin (1: Julibroside J(21)) with a xylopyranosyl moiety located at its C-21 side chain was isolated from Albizia julibrissin DURAZZ. (Leguminosae), and its structure was determined on the basis of comprehensive spectroscopic analyses. Compound 1 showed marked inhibitory action against Bel-7402 cancer cell line at 10 microg/ml.

Albizzia↗
PubMed2006

A pair of diastereoisomeric steroidal saponins from cytotoxic extracts of Tupistra chinensis rhizomes.

A pair of diastereoisomeric steroidal saponins were obtained from the saponin fraction (SF) of methanol extracts from Tupistra chinensis rhizomes, collected in Shennongjia Forest District, China. Based on the chemical and spectroscopic evidences, their structures were determined as shown in Fig. 1. The sample SF displayed marked inhibitory action in vitro towards HeLa and HL-60 cancer cell lines at 10 microg/ml by MTT method.

Cell Line, Tumor↗
PubMed2005

Cholesterol-mediated neurite outgrowth is differently regulated between cortical and hippocampal neurons.

The acquisition of neuronal type-specific morphogenesis is a central feature of neuronal differentiation and has important consequences for region-specific nervous system functions. Here, we report that the cell type-specific cholesterol profile determines the differential modulation of axon and dendrite outgrowths in hippocampal and cerebral cortical neurons in culture. The extent of axon and dendrite outgrowths is greater and the polarity formation occurs earlier in cortical neurons than in hippocampal neurons. The cholesterol concentrations in total homogenate and the lipid rafts from hippocampal neurons are significantly higher than those from cortical neurons. Cholesterol depletion by beta-cyclodextrin markedly enhanced the neurite outgrowth and accelerated the establishment of neuronal polarity in hippocampal neurons, which were similarly observed in nontreated cortical neurons, whereas cholesterol loading had no effects. In contrast, both depletion and loading of cholesterol decreased the neurite outgrowths in cortical neurons. The stimulation of neurite outgrowth and polarity formation induced by cholesterol depletion was accompanied by an enhanced localization of Fyn, a Src kinase, in the lipid rafts of hippocampal neurons. A concomitant treatment with beta-cyclodextrin and a Src family kinase inhibitor, PP2, specifically blocked axon outgrowth but not dendrite outgrowth (both of which were enhanced by beta-cyclodextrin) in hippocampal neurons, suggesting that axon outgrowth modulated by cholesterol is induced in a Fyn-dependent manner. These results suggest that cellular cholesterol modulates axon and dendrite outgrowths and neuronal polarization under culture conditions and also that the difference in cholesterol profile between hippocampal and cortical neurons underlies the difference in neurite outgrowth between these two types of neurons.

Animals↗
PubMed2005

Diastereoisomeric saponins from Albizia julibrissin.

The structures of four new diastereoisomeric triterpenoidal saponins Julibroside J5, J8, J12 and J13 (1-4) isolated from Albizia julibrissin Durazz. (Leguminosae) have been determined on the basis of comprehensive spectroscopic analysis and chemical degradation. Julibroside, J8 and J13 showed marked cytotoxic activities against Bel-7402 cancer cell line at 100 microg/mL.

Albizzia↗
PubMed2005

Oligomerization of amyloid beta-protein occurs during the isolation of lipid rafts.

Cholesterol- and glycosphingolipid-rich microdomains, called "lipid rafts," are suggested to initiate and promote the pathophysiology of Alzheimer's disease by serving as a platform for generation, aggregation, or degradation of amyloid-beta protein (Abeta). However, methods for biochemical isolation of these microdomains may produce artifacts. In this study, when synthetic Abeta1- 40 monomers were added to the brain fragment at a final concentration of 2.1 microM, followed by homogenization and isolation of lipid rafts by an established method, Abeta1- 40 accumulated as oligomers in the lipid raft fraction. However, in the absence of a brain homogenate, synthetic Abeta1- 40 did not accumulate in the lipid raft fraction. When fractionation was performed in the absence of synthetic Abeta1-40 and synthetic Abeta1-40 was incubated in an aliquot of each fraction, a marked oligomerization of Abeta1- 40 was observed in the lipid raft aliquot. These results indicate that exogenous Abeta associates with lipid rafts, and Abeta bound to rafts forms oligomers during the isolation of lipid rafts. In addition, endogenous Abeta1-40 in a Triton X-100-insoluble fraction of a brain homogenate of the Tg2576 transgenic mouse model of Alzheimer's disease formed oligomers when the fraction was incubated at 4 degrees C for 20 hr. Thus, one should be careful when one discusses the role of lipid rafts in amyloid precursor protein processing and in the generation, aggregation, and degradation of Abeta.

Alzheimer Disease↗
PubMed2005

Small molecule tgf-beta mimetics as potential neuroprotective factors.

Neurodegenerative and dementing illnesses are becoming an increasing social and economical burden as the number of older people continues to grow in industrialized countries. Current knowledge of the processes leading to these diseases is still limited, and very few effective treatments are available. Because neurodegeneration is associated with an activation of injury and innate immune responses in the brain, drugs that could mimic the beneficial aspects of this response are potential therapeutic candidates. The cytokine transforming growth factor (TGF)-beta1 is an organizer of the brain's response to injury and is known to be neuroprotective. Previous studies from our lab also showed that TGF-beta1 can reduce accumulation of beta-amyloid peptide (Abeta), which appears to be central to Alzheimer's disease (AD) pathogenesis, and we therefore initiated a search for small molecule chemical compounds that could mimic this effect. We report here the identification of several such TGF-beta mimetics detected in an in vitro screen of a library with 5000 chemically diverse compounds. If active in vivo, these mimetics could be developed into candidates for the treatment of neurodegeneration.

Alzheimer Disease↗
PubMed2004

Modulation of amyloid precursor protein cleavage by cellular sphingolipids.

Lipid rafts and their component, cholesterol, modulate the processing of beta-amyloid precursor protein (APP). However, the role of sphingolipids, another major component of lipid rafts, in APP processing remains undetermined. Here we report the effect of sphingolipid deficiency on APP processing in Chinese hamster ovary cells treated with a specific inhibitor of serine palmitoyltransferase, which catalyzes the first step of sphingolipid biosynthesis, and in a mutant LY-B strain defective in the LCB1 subunit of serine palmitoyltransferase. We found that in sphingolipid-deficient cells, the secretion of soluble APPalpha (sAPPalpha) and the generation of C-terminal fragment cleaved at alpha-site dramatically increased, whereas beta-cleavage activity remained unchanged, and the epsilon-cleavage activity decreased without alteration of the total APP level. The secretion of amyloid beta-protein 42 increased in sphingolipid-deficient cells, whereas that of amyloid beta-protein 40 did not. All of these alterations were restored in sphingolipid-deficient cells by adding exogenous sphingosine and in LY-B cells by transfection with cLCB1. Sphingolipid deficiency increased MAPK/ERK activity and a specific inhibitor of MAPK kinase, PD98059, restored sAPPalpha level, indicating that sphingolipid deficiency enhances sAPPalpha secretion via activation of MAPK/ERK pathway. These results suggest that not only the cellular level of cholesterol but also that of sphingolipids may be involved in the pathological process of Alzheimer's disease by modulating APP cleavage.

Amyloid beta-Protein Precursor↗
PubMed2004

Abeta(25-35)-induced memory impairment, axonal atrophy, and synaptic loss are ameliorated by M1, A metabolite of protopanaxadiol-type saponins.

We previously screened neurite outgrowth activities of several Ginseng drugs in human neuroblastoma, and demonstrated that protopanaxadiol (ppd)-type saponins were active constituents. Since ppd-type saponins are known to be completely metabolized to 20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol (M1) by intestinal bacteria when taken orally, M1 and ginsenoside Rb1, as a representative of ppd-type saponins, were examined for cognitive disorder. In a mouse model of Alzheimer's disease (AD) by Abeta(25-35) i.c.v. injection, impaired spatial memory was recovered by p.o. administration of ginsenoside Rb1 or M1. Although the expression levels of phosphorylated NF-H and synaptophysin were reduced in the cerebral cortex and the hippocampus of Abeta(25-35)-injected mice, their levels in ginsenoside Rb1- and M1-treated mice were almost completely recovered up to control levels. Potencies of the effects were not different between ginsenoside Rb1 and M1 when given orally, suggesting that most of the ginsenoside Rb1 may be metabolized to M1, and M1 is an active principal of ppd-type saponins for the memory improvement. In cultured rat cortical neurons, M1 showed extension activity of axons, but not dendrites. The axon-specific outgrowth was seen even when neuritic atrophy had already progressed in response to administration of Abeta(25-35) as well as in the normal condition. These results suggest that M1 has axonal extension activity in degenerated neurons, and improve memory disorder and synaptic loss induced by Abeta(25-35). M1 was shown to be effective in vitro and in vivo, indicating that Ginseng drugs containing ppd-type saponins may reactivate neuronal function in AD by p.o. administration.

Amyloid beta-Peptides↗
PubMed2004

Comparative study on triterpene saponins of Ginseng drugs.

A comparative study on the triterpene saponins of 47 samples of Ginseng drugs derived from 12 Panax taxa was conducted using a reverse-phase high-performance liquid chromatography (HPLC)method. Eleven ginsenosides, which represent 4 types of typical sapogenins, were chosen as standards for quantitative determination in order to characterize the chemical constituent pattern of each Ginseng drug and investigate the relationship between genetic varieties and chemical constituent pattern. The results showed that the ginsenoside compositions in Ginseng drugs of different origins were of considerable variability. Total saponin contents varied by 10-fold from the highest drug to the lowest one. Chikusetsu-ninjin derived from P. japonicus (Japan) was found to have the highest content (192.80 - 296.18 mg/g) and Ginseng from P. ginseng to be the lowest (5.78 - 15.63 mg/g). Two main groups (I and II) suggested by phytochemical data were clearly observed; group I mainly containing dammarane saponins consisted of P. ginseng, P. quinquefolius, P. notoginseng, P. vietnamensis and P. vietnamensis var. fuscidiscus; and group II containing a large amount of oleanolic acid saponins was com-posed of P.japonicus (apan), P. zingiberensis, P.japonicus (China),P. japonicus var. angustifolius, P. japonicus var. major, P. japonicus var. bipinnatifidus and P. stipuleanatus. The ratios of the subtotal of dammarane saponins to that of oleanolic acid saponins (D/0) were found to be > 1.9 and < 0.25 for groups I and II, respectively. The drug samples derived from the same botanical origin revealed similar constituent patterns, in other words, each Panaxtaxon showed its own characteristic chromatographic profile,which appeared in the specific shape of an 11-direction radar graph constructed on the basis of the result of quantitative analysis. Similarities of chemical constitution were seen among the closely phylogenetically-related taxa, including P. ginseng and P.quinquefolius, P. vietnamensis and P. vietnamensis var.fuscidiscus,P. japonicus (China) and its varieties were demonstrated, except P. japonicus (Japan) and P. zingiberensis.

Chromatography, High Pressure Liquid↗
PubMed2004

Simultaneous determination of triterpene saponins in ginseng drugs by high-performance liquid chromatography.

A HPLC method for the simultaneous determination of 11 triterpene saponins with four-type aglycones (protopanaxadiol, protopanaxatriol, ocotillol and oleanolic acid types) in Ginseng drugs was developed and validated. Using a gradient of acetonitrile and 10 mM K-phosphate buffer (pH 5.80) as the mobile phase and UV detection at 196 nm, more than 18 ginsenosides with different aglycones were separated satisfactorily within 60 min. The detection limits (signal/noise> or =3) were 0.1 microg for ginsenosides Rb1, Rc, Rd, Re and Rg1, chikusetsusaponin III, and notoginsenoside R2, 0.2 microg for gisenoside Ro and chikusetsusaponin IVa, 0.3 microg for chikusetsusaponin IV, and 3 microg for majonoside R2. The calibration curve of each saponin had a correlation coefficient close to 1. Intra- and interday precisions were less than 2.1% (n=5) and 3.3% (n=15), respectively. The recovery rates of extraction were in the range of 96.4-102.7% for all ginsenosides. By adopting this method, the determinations of 11 ginsenosides in three Ginseng drugs derived from Panax ginseng, Panax vietnamensis var. fuscidiscus and Panax japonicus (Japan) were achieved.

Calibration↗
PubMed2004

[A new triterpenoid saponin julibroside J24 from the stem bark of Albiza julibrissin].

OBJECTIVE: To separate chemical and active constituents from the stem bark of Albiza julibrissin. METHODS: Chromatography and spectral methods were used. RESULTS: 3-O-beta-D-xylopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->6)-beta-D-glucopyranosyl-21-O-[(6S)-2-trans-2-hydroxymethyl-6-methyl-6-O-[3-O-(6S)-2-trans-2-hydroxymethyl-6-methyl-6-hydroxy-2,7-octadienoyl)-beta-D-xylopyranosyl]-2,7-octadienoyl]-acacic acid-28-O-beta-D-glucopyranosyl-(1-->3)-[alpha-L-arabinofuranosyl-(1-->4)]-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl ester (1) was separated and identified. CONCLUSION: Compound 1 is a new saponin named as Julibroside J(24).

Albizzia↗
PubMed2004

[Research of ginsenosides in kou zi qi using HPLC-MS-MS].

AIM: To analyze the ginsenosides in Kou zi qi (rhizomes of Panax japonicus C. A. Mey. var. major (Burkill) C. Y. Wu et K. M. Feng), and to supply evidences for chemotaxanology of Panax species and clinical uses of Kou zi qi. METHODS: The ginsenosides were isolated by HPLC, then the positive- and negative-ion API-MS/MS of constituents collected from HPLC were measured. RESULTS: Eight ginsenosides were identified as ginsenoside Re, ginsenoside Ro, chikuseksusaponins IV, IVa, notoginsenoside R2, ginsenosides Rb1, Rc and Rd, respectively, based on comparison of retention time with those of standards by HPLC, and analysis on their API-MS/MS data. Ginsenoside Ro and chikuseksusaponin IVa are the major components of Kou zi qi. CONCLUSION: This plant had a close relationship to P. stipuleanatus, P. zinginensis and P. japonicus var major; a relatively remote relationship to P. ginseng and P. quinquefolius, in a view of chemotaxanology. Ginsenoside Ro and chikuseksusaponin IVa might be the anti-inflammatory constituents of Kou zi qi.

Chromatography, High Pressure Liquid↗
PubMed2003

Amyloid beta-protein (Abeta)1-40 protects neurons from damage induced by Abeta1-42 in culture and in rat brain.

Previously, we found that amyloid beta-protein (Abeta)1-42 exhibits neurotoxicity, while Abeta1-40 serves as an antioxidant molecule by quenching metal ions and inhibiting metal-mediated oxygen radical generation. Here, we show another neuroprotective action of nonamyloidogenic Abeta1-40 against Abeta1-42-induced neurotoxicity in culture and in vivo. Neuronal death was induced by Abeta1-42 at concentrations higher than 2 microm, which was prevented by concurrent treatment with Abeta1-40 in a dose-dependent manner. However, metal chelators did not prevent Abeta1-42-induced neuronal death. Circular dichroism spectroscopy showed that Abeta1-40 inhibited the beta-sheet transformation of Abeta1-42. Thioflavin-T assay and electron microscopy analysis revealed that Abeta1-40 inhibited the fibril formation of Abeta1-42. In contrast, Abeta1-16, Abeta25-35, and Abeta40-1 did not inhibit the fibril formation of Abeta1-42 nor prevent Abeta1-42-induced neuronal death. Abeta1-42 injection into the rat entorhinal cortex (EC) caused the hyperphosphorylation of tau on both sides of EC and hippocampus and increased the number of glial fibrillary acidic protein (GFAP)-positive astrocytes in the ipsilateral EC, which were prevented by the concurrent injection of Abeta1-40. These results indicate that Abeta1-40 protects neurons from Abeta1-42-induced neuronal damage in vitro and in vivo, not by sequestrating metals, but by inhibiting the beta-sheet transformation and fibril formation of Abeta1-42. Our data suggest a mechanism by which elevated Abeta1-42/Abeta1-40 ratio accelerates the development of Alzheimer's disease (AD) in familial AD.

Amyloid beta-Peptides↗
PubMed2002

Amyloid beta-protein affects cholesterol metabolism in cultured neurons: implications for pivotal role of cholesterol in the amyloid cascade.

Recently, we have found that alterations in cellular cholesterol metabolism are involved in promotion of tau phosphorylation (Fan et al. [2001] J. Neurochem. 76: 391-400; Sawamura et al. [2001] J. Biol. Chem. 276:10314-10319). In addition, we have shown that amyloid beta-protein (A beta) promotes cholesterol release to form A beta-lipid particles (Michikawa et al. [2001] J. Neurosci. 21:7226-7235). These lines of evidence inspired us to conduct further studies on whether A beta affects cholesterol metabolism in neurons, which might lead to tau phosphorylation. Here, we report the effect of A beta1-40 on cholesterol metabolism in cultured neurons prepared from rat cerebral cortex. Oligomeric A beta1-40 inhibited cholesterol synthesis and reduced cellular cholesterol levels in a dose- and time-dependent manner, while freshly dissolved A beta had no effect on cholesterol metabolism. However, oligomeric A beta had no effect on the proteolysis of sterol regulatory element binding protein-2 (SREBP-2) or protein synthesis in cultured neurons. Oligomeric A beta did not enhance lactate dehydrogenase (LDH) release from neuronal cells or decrease signals in the cultures reactive to 3,3'-Bis[N,N-bis(carboxymethyl)aminomethyl]fluorescein, hexaacetoxymethyl ester (calcein AM) staining, indicating that A beta used in this experiment did not cause neuronal death during the time course of our experiments. Since alterations in cholesterol metabolism induce tau phosphorylation, our findings that oligomeric A beta alters cellular cholesterol homeostasis may provide new insight into the mechanism underlying the amyloid cascade hypothesis.

Alzheimer Disease↗