Mechanistic insights into the amelioration effects of lipopolysaccharide-induced acute lung injury by baicalein: An integrated systems pharmacology study and experimental validation.

BACKGROUND: Acute lung injury is an acute progressive respiratory failure caused by several of non-cardiogenic factors which involves in excessive amplification or uncontrolled inflammatory response. OBJECTIVES: In this study, we investigated the protective effect of baicalein against acute lung injury induced by LPS and explored the underlying mechanisms. METHODS: Forty-eight SPF male C57BL/6 mice were randomly divided into normal group, model group, dexamethasone group and baicalein low-dose, medium-dose and high-dose groups. After 5 days of adaptive feeding, the mice were intraperitoneally injected with LPS and dissected after 12 h. Hematoxylin-eosin staining, ELISA assay, immunofluorescence assay and Western-Blot were applied to appraise microstructural changes and protein expressions of lung tissues. Systems pharmacology study was used to evaluate the protection of baicalein on acute lung injury. FINDINGS: The results showed that baicalein administration could significantly inhibit LPS-induced lung morphological changes, inhibit inflammatory response and pyroptosis. A total of forty-three potential targets of baicalein and acute lung injury were obtained. And PI3K-Akt, TNF and NF-κB were mainly signaling pathways. It is worth mentioning that this experiment also confirmed that NLRP3, caspase-1 and other inflammasome are involved in pyroptosis. CONCLUSION: Baicalein has protected against LPS-induced lung tissues injury via inhibiting inflammatory response and pyroptosis.

The Effects of Lysimachia christinae Hance Extract Fractions on Endothelium-Dependent Vasodilatation.

BACKGROUND: Endothelium-dependent dilatation is a predictor for vascular function. NADPH oxidase-derived O2- can inactivate nitric oxide and induce vascular injury. METHOD: The crude ethanolic extract of Lysimachia christinae Hance were separated out 4 fractions of different olarities by petroleum ether, ethyl acetate, n-butanol (NB), and aqueous. The endothelial integrity was appraised by vascular tension measurement. Dihydroethidium was utilized to observe the vascular reactive oxygen species (ROS) production. Western-blot was adopted to detect protein expression. RESULTS: Among the 4 fractions of L. christinae Hance, the NB fraction showed the most potent capacity of promoting endothelium-dependent vascular relaxation and inhibiting ROS formation in aortic rings, which were likely attributed by suppressing the expression of NAD(P)H oxidase subunit (gp91phox, p47phox, and p67phox) and enhancing the phosphorylation of endothelial NOS in vascular tone. CONCLUSIONS: These results suggest that the NB fraction possess the strongest vascular pharmacological activities among the crude ethanolic extract of L. christinae Hance, which may help us for purifying bioactive constituents and discovering new drugs from this herb in future.

Evaluation of the antioxidant and endothelial protective effects of Lysimachia christinae Hance (Jin Qian Cao) extract fractions.

BACKGROUND: Lysimachia christinae Hance is a traditional Chinese medicine with diuretic, detumescent, and detoxifying effects. Our aimed to optimize the extraction protocol to maximize the yield of flavonoids from Lysimachia christinae Hance, and evaluate the pharmacological activities of four fractions, namely, petroleum ether (PE), ethyl acetate (EA), n-butanol (NB), and aqueous (AQ) fractions, of the ethanolic extract of Lysimachia christinae Hance. METHODS: The flavonoid monomers in the crude extract were characterized via high performance liquid chromatography (HPLC), were used as markers for extract quality control and standardization. The total flavonoid, total phenolic, and total polysaccharide contents of each fraction were determined by spectrophotometry. Further, the in vitro free radical (diphenylpicrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), superoxide, and hydroxyl radicals) scavenging activities, and antioxidant capacity in endothelial cells were evaluated for each fraction. RESULTS: After optimizing the extraction protocol to maximize the total flavonoid yield from L. christinae Hance, the NB fractions had the highest total flavonoid (39.4 ± 4.55 mg RE/g), total phenolic (41.1 ± 3.07 mg GAE/g) and total polysaccharide (168.1 ± 7.07 mg GE/g); In addition, the NB fraction of the ethanolic extract of L. christinae Hance reveal the strongest radical-scavenging activity, antioxidant activity and protective effects against H2O2-induced injury in HUVECs. CONCLUSIONS: Among the four fractions of L. christinae Hance, the NB fraction showed the most potent antioxidant and endothelial protective effects, which may be attributed to its high flavonoid, phenolic contents and optimal portfolio of different active ingredients of NB fractions of the ethanolic extract of L. christinae Hance. This study might improve our understanding of the pharmacological activities of L. christinae Hance, thereby facilitating its use in disease prevention and treatment.

Emerging Benefits: Pathophysiological Functions and Target Drugs of the Sigma-1 Receptor in Neurodegenerative Diseases.

The sigma-1 receptor (Sig-1R) is encoded by the SIGMAR1 gene and is a nonopioid transmembrane receptor located in the mitochondrial-associated endoplasmic reticulum membrane (MAM). It helps to locate endoplasmic reticulum calcium channels, regulates calcium homeostasis, and acts as a molecular chaperone to control cell fate and participate in signal transduction. It plays an important role in protecting neurons through a variety of signaling pathways and participates in the regulation of cognition and motor behavior closely related to neurodegenerative diseases. Based on its neuroprotective effects, Sig-1R has now become a breakthrough target for alleviating Alzheimer's disease and other neurodegenerative diseases. This article reviews the most cutting-edge research on the function of Sig-1R under normal or pathologic conditions and target drugs of the sigma-1 receptor in neurodegenerative diseases.

An inhibitory role of p53 via NF-kappaB element on the cyclin D1 gene under heat shock.

Little is known about the mechanisms underlying heat shock-mediated inhibition of cyclin D1 transcription. Here, we report that NF-kappaB site-mediated cyclin D1 transcription is inhibited by heat shock. The mRNA level of cyclin D1 decreased under heat shock (40-60%). This inhibition of transcription is promoter activity dependent and is mediated by the proximal NF-kappaB site. However, P65 overexpression did not influence the heat-inducible inhibitory pattern and heat shock did not significantly change the binding activity of p65. P53 can inhibit cyclin D1 promoter activity via an NF-kappaB site-dependent manner and its binding activity increased after heat shock. Importantly, p53 overexpression can prevent cyclin D1 promoter activation by p65. Therefore, we can deduce that p53 inhibits promoter activity under heat shock. These results reveal that the mechanism of heat shock-mediated inhibition of cyclin D1 transcription involves an NF-kappaB site. The data presented provide a new insight into the underlying heat shock inhibition of gene transcription.

CARM1 activates myogenin gene via PCAF in the early differentiation of TPA-induced rhabdomyosarcoma-derived cells.

CARM1/PRMT4 is a member of the protein arginine methyltransferase (PRMT) family. CARM1 as a transcriptional coactivator plays an active role on mammalian genes. Here, we show that CARM1 can be recruited to the promoter of myogenin gene to enhance its transcriptional activation via PCAF at the early stage of TPA-induced RD cell differentiation. By adding adenosine dialdehyde, AdOx, to inhibit the PRMT in RD cells, the TPA-induced recruiting of p300, PCAF and the Brg1 at the myogenin promoter is abolished and myogenic differentiation is blocked. More specifically, the expression of PCAF and its nucleation are prohibited when CARM1 is knockdown by its specific siRNA. We suggest that the physical interaction of CARM1 and PCAF is likely pivotal for the activation of PCAF in the downstream of CARM1 pathway for inducing myogenin under TPA-induced differentiation. The findings shed lights on novel therapeutic targets in the treatment of rhabdomyosarcoma patients.

Role of acetylated p53 in regulating the expression of map2 in retinoic acid-induced P19 cells.

OBJECTIVE: To investigate the regulatory mechanisms of acetylated p53 in the expression of microtubule-associated protein-2 (MAP2) in neuronal differentiation of P19 cells induced by all-trans retinoic acid (RA). METHODS: Neuronal differentiation of P19 cells was initiated with 4-day RA treatment. Immunofluorescence, real-time reverse transcription-polymerase chain reaction (RT-PCR) assay, and map2 promoter driven luciferase assay were performed to detect the expression and relative promoter activity of MAP2 in those RA-treated cells. Real-time PCR-based chromatin immunoprecipitation assay (ChIP) was carried out to reveal the specific recruitment of acetylated p53 onto its binding sites on map2 promoter. RESULTS: The expression of MAP2 was markedly increased in RA-induced P19 cells. The map2 mRNA increased 34-fold after 4 days of RA treatment and 730-fold 2 days after the treatment, compared with the cells without RA treatment (control). p53 was recruited to the promoter of map2 gene in acetylated form and thereby enhanced its promoter activity. p300/CBP associated factor (PCAF) was found induced in RA-treated cells and enriched in the nucleus, which might contribute to the acetylation of p53 in the regulation of map2 gene. CONCLUSIONS: Acetylated p53 may participate in regulating the expression of map2 in RA-induced differentiation of P19 cells. PCAF is possibly involved in this process by mediating the acetylation of p53.

Histone marks and chromatin remodelers on the regulation of neurogenin1 gene in RA induced neuronal differentiation of P19 cells.

Neurogenin1 is an important bHLH protein that plays crucial role in neurogenesis. We first show that the expression of ngn1 increases drastically in RA induced neuronal differentiation. During which, a three successive stages of the epigenetic changes surrounding the ngn1 gene are found correlated with a repression to activation of the gene in P19 cells. Recruiting of a repressive histone code H3K27me3 on the ngn1 gene is the dominant change in first repression stage, which is followed by the binding of the active codes of H3K9ac, H3K14ac, and the H3K4me3 in the second and third stages of RA treatment. Additionally, BRM but not BRG1 is specifically recruited to ngn1 gene at the third stage and is positively involved in the RA induced ngn1 expression. We propose that histone modifiers and chromatin remodelers are pivotal in the activation of the ngn1 gene in RA induced differentiation of P19 cells.

Resistance to geldanamycin-induced apoptosis in differentiated neuroblastoma SH-SY5Y cells.

Geldanamycin (GA) is a specific inhibitor of the 90 kDs heat shock protein (Hsp90) in the cytoplasm of mammalian cells, which binds directly to Hsp90 and promotes proteolytic degradation of its client proteins. As an antitumor drug, GA antagonizes the protecting effects of Hsp90 on cell survival, while its mechanisms remain unclear. Here, we show that GA induces apoptosis in a human neuroblastoma cell line, SH-SY5Y. Treatment of the cells with all trans retinoic acid (RA) generates a neuron-like, morphological change of differentiation, and results in the activation of ERK and Akt pathways, an inhibition of the nuclear translocation of p53 induced by GA, and induces higher resistance to the GA-induced apoptosis. These results provide the first evidence for the requirement of p53 nucleation in SH-SY5Y cells to counteract GA in neuron survival.

Differential hypersensitivity to DNase I in the regulatory region of human hsp90 beta gene in heat shock and constitutive expression.

DNase I hypersensitivity analysis is a useful tool to investigate impact of structure changes in chromatin on the expression of a gene. In order to unravel chromatin regulation on human hsp90 beta gene, differential sensitivity to DNase I in non-treated and heat-shocked Jurkat cells are examined. Four major hypersensitive sites at -120/-20 bp (HS1), +360 bp (HS2), +630/+780 bp (HS4) and around +1020 bp (HS5) with respect to the transcription start site of hsp90 beta gene have been identified. The HS1 is shared by both constitutive and heat shock, while the intronic sites of HS4 and HS5 are elicited by heat shock and HS2 is illustrated only in constitutive expression. In addition, distal HSs at around 8.7 kb upstream and 6.8 kb downstream are found in both constitutive and heat shock expression, which indicate that the boundaries of the hsp90 beta gene extend for some 16 kb. The HS patterns confirm chromatin regulation in the expression of hsp90 beta gene under various treatments.

[Chromatin immunoprecipitation and its preliminary application for gene regulation].

OBJECTIVE: To verify the binding of p53 to p21WAF1/CIP1 gene promoter and detect its binding to hsp90 beta gene promoter in vivo. METHODS: Chromatin immunoprecipitation and PCR analysis were used to measure specific gene regulation sequence and Western blot analysis to investigate p53 protein. RESULTS: The p53 binding sequences on the promoters of p21WAF1/CIP1 and hsp90 beta gene were found in the p53 antibody immunoprecipitated DNA fragments and p53 was detected in the immunoprecipitated samples. CONCLUSIONS: p53 binds to promoters of p21WAF1/CIP1 and hsp90 beta gene in vivo, and regulates the expression of the two genes.

[Heat shock activated Rac-MEKK-JNK pathway and hsp90 beta gene expression].

OBJECTIVE: To study the effect of Rac-MEKK-JNK (Rac-mitogen activated protein kinase kinase kinase-C-jun N-terminal protein kinase) signal pathway on heat shock-induced hsp90 beta gene expression and the impact of Hsp90 on the regulation of the pathway. METHODS: DN-Rac, DN-MEKK or DN-JNK were cotransfected with hsp90 beta CAT reporter plasmid beta 3.1 into Jurkat or LETPa-2 cells individually, the CAT mRNA expression was then determined quantitatively by competitive RT-PCR based system. Western blot was carried out to detect the expression level and phosphorylation of c-Jun in Jurkat and LETPa-2 cells that were transfected with DN-Rac, DN-MEKK or DN-JNK. By in vitro kinase activity assay and Western blot, the effect of geldnamycin (GA) on heat induced JNK activity were evaluated. RESULTS: In Jurkat cell transfected with DN-Rac, DN-MEKK or DN-JNK, heat shock induced relative CAT mRNA expression level was decreased to (72.8 +/- 5)%, (60 +/- 13.2)% and (47.7 +/- 12.1)% of the control respectively; while in LETPa-2 cell hsp90 beta 3.1 reporter gene expression was accordingly suppressed to (16.17 +/- 5.1)%, (50.2 +/- 8.7)% and (47.5 +/- 10)% of control. C-Jun expression and phosphorylation were inhibited by the transfection of either one of DN-Rac, DN-MEKK or DN-JNK. With GA treatment, heat shock induced JNK activity was repressed, while the expression level of JNK or c-Jun was not obviously changed. CONCLUSIONS: Rac-MEKK-JNK pathway promotes heat shock induced hsp90 beta gene expression and hsp90 may participate in the regulation of heat shock activated Rac-MEKK-JNK signal pathway in both Jurkat and LETPa-2 cells.

[Screening, cloning, and analyzing for hSNF5 binding proteins in human fetal brain].

OBJECTIVE: To identify novel binding proteins of hSNF5, a subunit of chromatin remodeling complex in human fetal brain. METHODS: The yeast two-hybrid system was used for this study. Positive cDNA clones were sequenced. Sequence homology and putative functional domains were analyzed and compared with databank. RESULTS: Nine positive clones obtained were analyzed, among which the sequence of one clone was 97% homologous to the 3' mRNA of a hypothetical protein FLJ20643, while other four clones were related to protein coding sequences existed in the GenBank. The rest four clones were not in frame with any known protein coding sequence. CONCLUSIONS: Clones encoding for hSNF5 binding protein exists in cDNA library of human brain. These proteins may recruit chromatin remodeling complex via hSNF5 to modulate the transcription of their target gene and the related cell functions.

[Cloning cDNA encoding for GAGA-like element binding proteins in human Jurkat cells].

OBJECTIVE: To explore GAGA-like element binding protein in human cells. METHODS: Yeast one-hybrid system was used to screen the GAGA-like element binding proteins in HTLV-1 transformed Jurkat cell cDNA fusion library. Total RNA extracted from Jurkat cells was first labeled by reverse transcription, and was taken as cDNA probe to hybridize with the candidate positive clones. RESULTS: 9 positive clones were obtained, and 6 out of the 9 clones were positively hybridized with the cDNA probe. CONCLUSIONS: 6 candidate clones encoding for GAGA-like element binding proteins were obtained from Jurkat cells for further investigation.

[The role of p53 binding site on the trans binding of p53 to Hsp90 beta gene].

OBJECTIVE: To investigate the effect of p53 binding site (+31/+60) of hsp90 beta gene on its transcriptional regulation. METHODS: The binding site was first inserted into pBS-SK. After the plasmid annealing and elongation with mutagenic and selective primers, nuclease digestion and bacteria transformation was performed twice to select the positive mutated plasmid. Electrophoretic mobility shift assays (EMSA) was employed to detect the binding of hsp90 beta gene fragment containing mutated p53 binding site and Jurkat cell nuclear extract transfected by p53 expression vector. RESULTS: The sequence analysis profile confirmed a successful mutation of two bases on the core sequence of the second half binding site. EMSA results showed the specific DNA-protein complex band disappeared after the mutation. CONCLUSIONS: The core sequence of p53 binding site plays a key role in the trans binding of p53 to hsp90 beta gene.

[Establishment and application of a RT-PCR system for quantifying mRNA of 4 hsp genes in human cells].

OBJECTIVE: To establish a RT-PCR system for detecting mRNA expression level of 4 hsp genes in human cells. METHODS: RT-PCR system was established with gene cloning, gene recombination, in vitro transcription and RT-PCR techniques; The detection of expression level of 4 hsp genes in SW13 cell was carried out with this system. RESULTS: In SW13 cell, hsp70 and hsp90 alpha were typical heat shock induced genes, while hsp60 and hsp90 beta were efficiently expressed and further induced by heat-shock to various extent. CONCLUSIONS: In our hands novel RT-PCR system can be used to detect mRNA expression level of 4 human hsp genes.

[Enhanced action of a BTB/POZ domain protein on the expression of hsp90alpha gene in heat shock].

OBJECTIVE: To study the role of a BTB/POZ domain protein in the expression of hsp90alpha gene. METHODS: The eukaryotic expression plasmids of sense- and antisense-GAGA related protein (GRP) or empty vector were transfected into Jurkat cells with pREP4 episomal vector plasmids carrying the hsp90alpha promoter sequence from -1756 to +37 and control plasmids pMCAT. Total RNA was extracted. The relative promoter activity of hsp90alpha-CAT reporter gene was determined by competitive RT-PCR assay. RESULTS: GRP markly increased the relative promoter activity of hsp90alpha-CAT reporter gene during heat shock. CONCLUSION: GRP may promote the expression of hsp90alpha gene by participating in chromatin remolding.

[Heat shock induced transcription of hsp90alpha gene on chromatin template].

OBJECTIVE: A CAT reporter plasmid (pBLCAT3alpha1) driven by the promoter of hsp90alpha was in vitro assembled into chromatin to investigate the transcription activity of the reporter gene upon heat shock. METHODS: A competitive RT-PCR-based technique was used to quantify the promoter activity of hsp90alpha gene on chromatin or naked DNA templates in vitro. RESULTS: The in vitro transcription efficiency was first optimized by using different amounts of whole cell extracts from heat shock-treated HeLa cells. In vitro chromatin assembly was carried out with purified components of chromatin assembly associated factors, core histones and CAT reporter gene driven by the promoter of hsp90alpha gene. Results showed that chromatin formation repressed the in vitro transcription of the gene. CONCLUSION: The heat shock induced transcription of hsp90alpha gene on chromatin template is more efficient than that on naked DNA in vitro.

HDAC3 augments the autoregulation of neuroD gene in P19 cells.

NeuroD, a basic helix-loop-helix transcription factor, is capable of converting embryonic epidermal cells into neuronal cells. However, whether histone deacetylases (HDACs) are involved in the autoregulation of neuroD or not is unclear. In this study, neuroD expression was found to be significantly increased in the all-trans retinoid acid-treated P19 cells. Meanwhile, neuroD could itself enhance its promoter activity and mRNA expression. By using specific inhibitors to histone modification enzymes, HDAC3 was identified to specifically augment the autoactivation of neuroD in P19 cells. The data suggest that the elevation of HDAC3 and neuroD in all-trans retinoid acid-treated cells exponentially increases the neuroD expression and mediates an early commitment of P19 cells for neuronal differentiation.

A switch from hBrm to Brg1 at IFNγ-activated sequences mediates the activation of human genes.

The SWI/SNF chromatin-remodeling complexes utilize energy from ATP hydrolysis to reposition nucleosomes and regulate the expression of human genes. Here, we studied the roles of human Brahma (hBrm) and Brahma-related gene 1 (Brg1), the ATPase subunits of the SWI/SNF complexes, in regulating human genes. Our results indicate that both hBrm and Brg1 interact with Signal transducer and activator of transcription (Stat) 1 in vitro. However, Stat1 in its native form only recruits hBrm to IFNγ-activated sequences (GAS) of individual genes; by contrast, in a stress-induced phosphorylated form, Stat1 mainly binds to Brg1. Under basal conditions, hBrm is recruited by native Stat1 to the GAS and exists in a mSin3/HDAC co-repressor complex on the hsp90α gene, which shows a compact chromatin structure. Upon heat-shock, hBrm is acetylated by p300 and dissociates from the co-repressor complex, which the phosphorylated Stat1 is increased, and binds and recruits Brg1 to the GAS, leading to elevated induction of the gene. This hBrm/Brg1 switch also occurs at the GAS of all of the three examined immune genes in heat-shocked cells; however, this switch only occurs in specific cell types upon exposure to IFNγ. Regardless of the stimulus, the hBrm/Brg1 switch at the GAS elicits an increase in gene activity. Our data are consistent with the hypothesis that the hBrm/Brg1 switch is an indicator of the responsiveness of a gene to heat-shock or IFNγ stimulation and may represent an "on-off switch" of gene expression in vivo.