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Ganoderma lucidum polysaccharides in human monocytic leukemia cells: from gene expression to network construction.

Cheng KC, Huang HC, Chen JH, Hsu JW, Cheng HC, Ou CH, Yang WB, Chen ST, Wong CH, Juan HF - BMC Genomics (2007)

Bottom Line: In previous studies, F3, the active component of the polysaccharide extract, was found to activate various cytokines such as IL-1, IL-6, IL-12, and TNF-alpha.The apoptosis induction through the DR3 and DR4/5 death receptors was found to be one of the most significant pathways and play a key role in THP-1 cells after F3 treatment.Our results showed that F3 may induce death receptor ligands to initiate signaling via receptor oligomerization, recruitment of specialized adaptor proteins and activation of caspase cascades.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Life Science, National Taiwan University, Taipei 106, Taiwan. jerekcheng@gmail.com

ABSTRACT

Background: Ganoderma lucidum has been widely used as a herbal medicine for promoting health and longevity in China and other Asian countries. Polysaccharide extracts from Ganoderma lucidum have been reported to exhibit immuno-modulating and anti-tumor activities. In previous studies, F3, the active component of the polysaccharide extract, was found to activate various cytokines such as IL-1, IL-6, IL-12, and TNF-alpha. This gave rise to our investigation on how F3 stimulates immuno-modulating or anti-tumor effects in human leukemia THP-1 cells.

Results: Here, we integrated time-course DNA microarray analysis, quantitative PCR assays, and bioinformatics methods to study the F3-induced effects in THP-1 cells. Significantly disturbed pathways induced by F3 were identified with statistical analysis on microarray data. The apoptosis induction through the DR3 and DR4/5 death receptors was found to be one of the most significant pathways and play a key role in THP-1 cells after F3 treatment. Based on time-course gene expression measurements of the identified pathway, we reconstructed a plausible regulatory network of the involved genes using reverse-engineering computational approach.

Conclusion: Our results showed that F3 may induce death receptor ligands to initiate signaling via receptor oligomerization, recruitment of specialized adaptor proteins and activation of caspase cascades.

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Related in: MedlinePlus

Proposed F3-induced cell death pathways in THP-1 cells. Based on our self-developed software for the reconstruction of gene networks in addition to literature research, we proposed plausible cell death pathways induced by F3 in THP-1 cells. F3 may induce death receptor ligands (TNF-α and TRAIL) to initiate signaling via receptor oligomerization, recruitment of specialized adaptor proteins and activation of caspase cascades. Lastly, cell shrinkage and apoptosis occur.
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Figure 10: Proposed F3-induced cell death pathways in THP-1 cells. Based on our self-developed software for the reconstruction of gene networks in addition to literature research, we proposed plausible cell death pathways induced by F3 in THP-1 cells. F3 may induce death receptor ligands (TNF-α and TRAIL) to initiate signaling via receptor oligomerization, recruitment of specialized adaptor proteins and activation of caspase cascades. Lastly, cell shrinkage and apoptosis occur.

Mentions: Based on our time-course Q-PCR data, we constructed the cell death gene network in F3-treated THP-1 cells by our self-developed software tool, BSIP [55]. Assuming that gene regulatory network follows the S-system mathematical model [56], we used BSIP to estimate the modeling parameters, identify the optimized structure, compare the concordance, and infer a plausible regulatory network. Moreover, we established the interrelated apoptosis pathways initiated by F3 in THP-1 cells using our concurrent findings, as illustrated in Figure 10. Death receptors, which belong to tumor necrosis factor (TNF) gene superfamily, are cell surface receptors that transmit apoptosis signals and play a crucial role in apoptosis and cell survival. Our characterized death receptors are TNFR1 (tumor necrosis factor receptor-1), TNFR2 (tumor necrosis factor receptor-2), and DR4/5 (also called TRAIL-R1/2) [31]. TNF-α and TNFSF10, also called TRAIL, exhibit an increase in gene expression in F3-treated THP-1 cells. When TNF-α binds to TNFR1, adaptor protein TRADD recruitment follows, and then it interacts with another death domain-containing molecule FADD, leading to the subsequent cleavage of pro-caspase-8 [57]. The binding of TRAIL to DR4/5 also induces the recruitment of FADD and pro-caspase-8 of auto-proteolytic activation [37]. Interactions between pro-caspase-8 and FADD result in further activation of caspase-3 and caspase-7, and also the initiation of apoptosis [58]. In addition to apoptotic signals, recruitment of TRAF2 through TNFR2 binding TNF-α activates NF-κB, thus producing anti-apoptotic signals [59]. TNFR1 also activates anti-apoptotic NF-κB. NF-κB-dependent activation of TRAF2, RIPK1, and BIRC2 gene expressions seemed to support this because TRAF2 and RIP interacting with TRADD prevented caspase-8 activation, while c-IAPs inhibited caspase-3 and caspase-7 activation [60]. When NF-κB is activated, IκB is phosphorylated by protein kinase IKK and this phosphorylation serves as a signal for the ubiquitination and degradation of IκB. Free NF-κB dimers are released and translocated to the nucleus, where they enhance the transcription of target genes. NF-κB activation and IκB degradation prompt cell survival signals and mediate immune responses [61]. In contract, NF-κB is a transcription factor that regulates expression of a large number of genes critical for the regulation of apoptosis, and many reports have showed that Apo2L/TRAIL can activate NF-κB [29,49]. All in all, NF-κB activation can promote apoptosis or survival, depending on the cellular contents [49].


Ganoderma lucidum polysaccharides in human monocytic leukemia cells: from gene expression to network construction.

Cheng KC, Huang HC, Chen JH, Hsu JW, Cheng HC, Ou CH, Yang WB, Chen ST, Wong CH, Juan HF - BMC Genomics (2007)

Proposed F3-induced cell death pathways in THP-1 cells. Based on our self-developed software for the reconstruction of gene networks in addition to literature research, we proposed plausible cell death pathways induced by F3 in THP-1 cells. F3 may induce death receptor ligands (TNF-α and TRAIL) to initiate signaling via receptor oligomerization, recruitment of specialized adaptor proteins and activation of caspase cascades. Lastly, cell shrinkage and apoptosis occur.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2211495&req=5

Figure 10: Proposed F3-induced cell death pathways in THP-1 cells. Based on our self-developed software for the reconstruction of gene networks in addition to literature research, we proposed plausible cell death pathways induced by F3 in THP-1 cells. F3 may induce death receptor ligands (TNF-α and TRAIL) to initiate signaling via receptor oligomerization, recruitment of specialized adaptor proteins and activation of caspase cascades. Lastly, cell shrinkage and apoptosis occur.
Mentions: Based on our time-course Q-PCR data, we constructed the cell death gene network in F3-treated THP-1 cells by our self-developed software tool, BSIP [55]. Assuming that gene regulatory network follows the S-system mathematical model [56], we used BSIP to estimate the modeling parameters, identify the optimized structure, compare the concordance, and infer a plausible regulatory network. Moreover, we established the interrelated apoptosis pathways initiated by F3 in THP-1 cells using our concurrent findings, as illustrated in Figure 10. Death receptors, which belong to tumor necrosis factor (TNF) gene superfamily, are cell surface receptors that transmit apoptosis signals and play a crucial role in apoptosis and cell survival. Our characterized death receptors are TNFR1 (tumor necrosis factor receptor-1), TNFR2 (tumor necrosis factor receptor-2), and DR4/5 (also called TRAIL-R1/2) [31]. TNF-α and TNFSF10, also called TRAIL, exhibit an increase in gene expression in F3-treated THP-1 cells. When TNF-α binds to TNFR1, adaptor protein TRADD recruitment follows, and then it interacts with another death domain-containing molecule FADD, leading to the subsequent cleavage of pro-caspase-8 [57]. The binding of TRAIL to DR4/5 also induces the recruitment of FADD and pro-caspase-8 of auto-proteolytic activation [37]. Interactions between pro-caspase-8 and FADD result in further activation of caspase-3 and caspase-7, and also the initiation of apoptosis [58]. In addition to apoptotic signals, recruitment of TRAF2 through TNFR2 binding TNF-α activates NF-κB, thus producing anti-apoptotic signals [59]. TNFR1 also activates anti-apoptotic NF-κB. NF-κB-dependent activation of TRAF2, RIPK1, and BIRC2 gene expressions seemed to support this because TRAF2 and RIP interacting with TRADD prevented caspase-8 activation, while c-IAPs inhibited caspase-3 and caspase-7 activation [60]. When NF-κB is activated, IκB is phosphorylated by protein kinase IKK and this phosphorylation serves as a signal for the ubiquitination and degradation of IκB. Free NF-κB dimers are released and translocated to the nucleus, where they enhance the transcription of target genes. NF-κB activation and IκB degradation prompt cell survival signals and mediate immune responses [61]. In contract, NF-κB is a transcription factor that regulates expression of a large number of genes critical for the regulation of apoptosis, and many reports have showed that Apo2L/TRAIL can activate NF-κB [29,49]. All in all, NF-κB activation can promote apoptosis or survival, depending on the cellular contents [49].

Bottom Line: In previous studies, F3, the active component of the polysaccharide extract, was found to activate various cytokines such as IL-1, IL-6, IL-12, and TNF-alpha.The apoptosis induction through the DR3 and DR4/5 death receptors was found to be one of the most significant pathways and play a key role in THP-1 cells after F3 treatment.Our results showed that F3 may induce death receptor ligands to initiate signaling via receptor oligomerization, recruitment of specialized adaptor proteins and activation of caspase cascades.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Life Science, National Taiwan University, Taipei 106, Taiwan. jerekcheng@gmail.com

ABSTRACT

Background: Ganoderma lucidum has been widely used as a herbal medicine for promoting health and longevity in China and other Asian countries. Polysaccharide extracts from Ganoderma lucidum have been reported to exhibit immuno-modulating and anti-tumor activities. In previous studies, F3, the active component of the polysaccharide extract, was found to activate various cytokines such as IL-1, IL-6, IL-12, and TNF-alpha. This gave rise to our investigation on how F3 stimulates immuno-modulating or anti-tumor effects in human leukemia THP-1 cells.

Results: Here, we integrated time-course DNA microarray analysis, quantitative PCR assays, and bioinformatics methods to study the F3-induced effects in THP-1 cells. Significantly disturbed pathways induced by F3 were identified with statistical analysis on microarray data. The apoptosis induction through the DR3 and DR4/5 death receptors was found to be one of the most significant pathways and play a key role in THP-1 cells after F3 treatment. Based on time-course gene expression measurements of the identified pathway, we reconstructed a plausible regulatory network of the involved genes using reverse-engineering computational approach.

Conclusion: Our results showed that F3 may induce death receptor ligands to initiate signaling via receptor oligomerization, recruitment of specialized adaptor proteins and activation of caspase cascades.

Show MeSH
Related in: MedlinePlus