A novel apidaecin Api-PR19 synergizes with the gut microbial community to maintain intestinal health and promote growth performance of broilers

Background: Antibiotic growth promoters(AGPs) have been used as growth promoters to maintain animal intestinal health and improve feed efficiency in broilers by inhibiting pathogen proliferation. In view of the growing emergence of antibiotic-resistant pathogen strains and drug residue issues, novel treatments are increasingly required. This study aimed to compare two antimicrobial approaches for managing pathogen infection and maintaining animal intestinal health in broilers by supplying Apidaecin Api-PR19 and AGPs over 42 d of a feeding trial.Results: Compared with the broilers that were only fed a corn-soybean basal diet(CON group), supplementation with Api-PR19 and AGP(respectively named the ABP and AGP groups) both increased the feed conversion efficiency. When compared with the AGP group, Api-PR19 supplementation could significantly increase the organ index of the bursa of fabricius and subtype H9 antibody level in broiler chickens. Moreover, when compared with the CON group, the intestinal villus height, intestinal nutrient transport, and intestinal s Ig A content were all increased in the Api-PR19 group, while AGP supplementation was harmful to the intestinal villus height and intestinal nutrient transport. By assessing the antibacterial effect of Api-PR19 and antibiotics in vitro and in vivo, we found that Api-PR19 and antibiotics both inhibited the growth of pathogens, including Escherichia coli and Campylobacter jejuni. Furthermore, by using 16 S r RNA gene sequencing, the beneficial bacteria and microbiota in broilers were not disturbed but improved by apidaecin Api-PR19, including the genera of Eubacterium and Christensenella and the species of uncultured_Eubacterium_sp, Clostridium_asparagiforme, and uncultured_Christensenella_sp, which were positively related to improved intestinal development, absorption, and immune function.Conclusion: Apidaecin Api-PR19 treatment could combat pathogen infection and had little negative impact on beneficial bacteria in the gut compared to antibiotic treatment, subsequently improving intestinal development,absorption, and immune function.

Cloning and Functional Analysis of the Porcine Growth Hormone Gene Promoter

[Objective] This study aimed to clone the porcine growth hormone gene promoter and determine the core promoter sequences and the cis-acting elements. [Method] Sequence of the 5＇flanking region of porcine growth hormone gene was searched out and downloaded from the NCBI website. According to the targeted se- quence, primers were designed and synthesized for the PCR amplification. The 1 882 bp （-1 821 bp-＋61 bp） fragment was amplified by PCR. Nine promoter frag- ments with different lengths were obtained by genome-walking deletion method and then cloned into luciferase reporter vectors. Relative transcriptional activities of these 5＇ terminal-deleted plasmids in pituitary and non-pituitary cells were determined by transient transfection of the rat pituitary adenoma cell （GH3）, porcine lilac endotheli- um cell （PIEC） and porcrne Kidney-15 （PK15） with the constructed dual-luciferase vectors. [Result] Result of DNA sequencing showed that the 1 882 bp fragment of GH 5＇ promoter was successfully cloned. Nine luciferase reporter gene plasmids were constructed. DuaI-Luciferase reporter assay indicated that the promoter inserted into reporter gene vector had very strong cell specificity. [Conclusion] Porcine growth hormone gene specifically expresses in pituitary cells. The minimal promoter of the porcine growth hormone gene is mapped at the region -110 bp-＋61 bp. Promoter regions 218 bp--110 bp and -429 bp--218 bp contain positive regulatory elements.

Semaphorin 3A: from growth cone repellent to promoter of neuronal regeneration

Highlight Semaphorin 3A is a classically known axonal guidance cue that mediates axonal growth cone repulsion and collapse.Recent works,however,suggest that it may have the apparently diametrically opposite activity of promoting neuronal regeneration.

Utilizing the γ-Irradiated Sodium Alginate as a Plant Growth Promoter for Enhancing the Growth,Physiological Activities,and Alkaloids Production in Catharanthus roseus L.

Sodium alginate is a polysaccharide that is largely obtained from the brown algae （Sargassum sp.）.It has been used as a wonderful growth promoting substance in its depolymerized form for various plants.The aim of this study was to find out the effects of various concentrations of γ-irradiated sodium alginate （ISA）,viz.,deionized water （control,T0）,20 （T1）,40 （T2）,60 （T3）,80 （T4）,and 100 ppm （T5） on the agricultural performance of Catharanthus roseus L.（Rosea） in terms of growth attributes,photosynthesis,physiological activities,and alkaloid production.The present work revealed that ISA applied as leaf-sprays at concentrations from 20 to 100 ppm might improve growth,photosynthesis,physiological activities,and alkaloid production in C.roseus L.significantly.Of the various ISA concentrations,80 ppm proved to be the best one compared to other concentrations applied.

Water Soluble Propolis and Royal Jelly Enhance the Antimicrobial Activity of Honeys and Promote the Growth of Human Macrophage Cell Line

Due to the overuse and misuse of antibiotic, an increase in antibiotic resistance of pathogenic bacteria is evolving. Attention should be focused on natural alternatives to antibiotics, like propolis, royal jelly （R J） and honeys. They all have strong antibacterial properties due to the active substances they contain. This study investigated the effect of combination of water soluble propolis （WSP） Greitl20 or fresh royal jelly （F-RJ） （MiZigoj） and Forest honeys as antibacterial against Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Acinetobacter baumanii, Staphylococcus aureus, methicillin resistant Staphylococcus aureus （MRSA）, Streptococcus pyogenes, Streptococcus agalactiae and Candida albicans. These substances are also cell growth promoters for human macrophage （TLT） cell line. WSP Greitl20, F-RJ （M） and different Forest honeys were prepared in saline as 10% solutions. The antimicrobial activity was expressed as the minimal inhibitory concentration （MIC） in mg/mL. The growth promotion activity was measured at optical density （OD） 595 nm. The combination ofWSP Greitl20 with different Forest honeys is better than F-RJ （M） in same combination with different Forest honeys. The best antibacterial/antifungal activity was found with the combination of 10% WSP Greit 120 in the Forest honey （1：10） from Italy or Spain. When measuring the growth promoting activity of TLT cell line, the best activity was detected at the combination of 10% WSP Greitl20 in the Forest honey from Italy （GI3 = 0.796 ± 0.014 and GI5 = 1.133± 0.022）. Antimicrobial and growth promoting activities are correlated and WSP-dependent.

Endophytic Bacteria Promote the Growth of Suaeda glauca in Saline-Alkali Stress:Regulation of Osmotic Pressure and Antioxidative Defense System

Endophytic bacteria are promising bacterial fertilizers to improve plant growth under adverse environment.For ecological remediation of coastal wetlands,it was necessary to investigate the effect and interaction of endophytes on halophytes under saline-alkali stress.In this study,an endophytic bacterium strain HK1 isolated from halophytes was selected to infect Suaeda glauca under pH(7 and 8)and salinity gradient(150,300 and 450mmolL^(-1)).Strain HK1 was identified as Pantoea ananatis and it had ability to fix nitrogen,dissolve inorganic phosphorus and produce indole-3-aceticacid(IAA).The results showed that strain HK1 could promote the growth of S.glauca seedings when the salinity was less than 300mmolL^(-1),in view of longer shoot length and heavier fresh weight.The infected plants could produce more proline to decrease the permeability of cells,which content increased by 26.2%–61.1%compared to the non-infected group.Moreover,the oxidative stress of infected plants was relieved with the malondialdehyde(MDA)content decreased by 16.8%–32.9%,and the peroxidase(POD)activity and catalase(CAT)activity increased by 100%–500%and 6.2%–71.4%,respectively.Statistical analysis revealed that increasing proline content and enhancing CAT and POD activities were the main pathways to alleviate saline-alkali stress by strain HK1 infection,and the latter might be more important.This study illustrated that endophytic bacteria could promote the growth of halophytes by regulation of osmotic substances and strengthening antioxidant activities.This finding would be helpful for the bioremediation of coastal soil.

<i>Tithonia diversifolia</i>Leaves and Stems Use as Substrate Amendment Promote the Growth of Plantain Vivoplants in the Nursery

Tithonia diversifolia is a year-round weed that decomposes rapidly after application as a soil amendment and it is more and more used in agriculture due to its numerous properties. The use of Tithonia diversifolia in the production of plantain vivoplants is a great opportunity for small holders’ farmers that cannot easily buy chemical inputs for yield improvement. All plant parts are used because of their richness in nutrients, mineral elements and phytochemicals without knowing which part is the most efficient. Tithonia diversifolia used as substrate amendment for plantain vivoplants production in nursery could promote their growth. This study aims to evaluate the effect of T. diversifolia leaves and stems as substrate amendment on plantain vivoplants growth promotion. The vivoplants were produced in substrates amended with T. diversifolia leaves, stems, combination of leaves and stems, and control without amendment. The vegetative growth parameters (number of shoots, height and diameter of shoots, area of shoots leaves) were assessed in sterilized substrate and unsterilized substrate conditions. T. diversifolia leaves and stems treatment increases the number of shoots, the height and the diameter of shoots as well as the area of shoots leaves compared to the control. T. diversifolia stems are the more efficient treatment, followed by the combination of T. diversifolia leaves and stems and finally the T. diversifolia leaves. They act as a biofertilizer promoting thus, the growth of plantain vivoplants in the nursery. All parts of Tithonia diversifolia can therefore be used by poor small holder farmers, as green manure for soil amendment in a green agriculture context.

Magnetic nanotechnology to study and promote axon growth

After injury of the central and peripheral nervous systems,functional recovery is impaired by axon regeneration failure.Various approaches for promoting axon growth have been attempted but their low efficacy has prevented them from being clinically applicable.

Research Progress on the Growth-Promoting Effect of Plant Biostimulants on Crops

A Plant Biostimulant is any substance or microorganism applied to plants to enhance nutrition efficiency,abioticstress tolerance,and/or crop quality traits,regardless of its nutrient content.The application of Plant biostimulants(PBs)in production can reduce the application of traditional pesticides and chemical fertilizers and improvethe quality and yield of crops,which is conducive to the sustainable development of agriculture.An in-depthunderstanding of the mechanism and effect of various PBs is very important for how to apply PBs reasonablyand effectively in the practice of crop production.This paper summarizes the main classification of PBs;Thegrowth promotion mechanism of PBs was analyzed from four aspects:improving soil physical and chemical properties,enhancing crop nutrient absorption capacity,photosynthesis capacity,and abiotic stress tolerance;At thesame time,the effects of PBs application on seed germination,seedling vigor,crop yield,and quality were summarized;Finally,how to continue to explore and study the use and mechanism of PBs in the future is analyzedand prospected,to better guide the application of PBs in crop production in the future.

Promotion of biomass, photosynthesis, and root growth of seedling biomass, photosynthesis, and root growth of Populus davidiana × P. bolleana by two species of ectomycorrhizal fungi

The addition of ectomycorrhizal fungi(ECMF),beneficial rhizosphere microorganisms,to the soil can pro-mote plant growth and resistance.Here,Populus davidi-ana×Populus bolleana tissue culture seedlings were grown for 3 months in soils inoculated with one of the species,then seedlings were assessed for mycorrhizal colonization rate and growth,physiological and root traits.Suillus luteus and Populus involutus each formed ectomycorrhizal associa-tions with the seedlings.Seedling height,ground diameter,biomass,and leaf area were significantly greater after treat-ment with ECMF than in the non-inoculated controls.Treat-ment improved all physiological and root variables assessed(chlorophylls and carotenoids,cellulose,and soluble sugars and proteins;root length,surface area,projected area,mean diameter,volume,number of root tips).Seedlings inocu-lated with S.luteus outperformed those inoculated with P.involutus.

Research Progress of Mechanism of Action of Plant Growth Promoting Rhizobacteria

The paper first introduces the definition and classification of plant growth promoting rhizobacteria （PGPR）, then reviews the research achievements on the mechanism of action of plant growth promoting rhizobacteria, including growth pro-moting mechanism and bio-control mechanism, subsequently lists the use of excel-lent plant growth promoting rhizobacteria strains in recent years, especial y Pseu-domonas and Bacil us strains, and final y discusses problems existing in this area and points out issues requiring further exploration, including PGPR screening meth-ods, preservation methods, mechanism of action, in order to commercialize PGPR as soon as possible and practical y realize its application to production.

Multiphasic characterization of a plant growth promoting bacterial strain, Burkholderia sp.7016 and its effect on tomato growth in the field

Aiming at searching for plant growth promoting rhizobacteria (PGPR), a bacterium strain coded as 7016 was isolated from soybean rhizosphere and was characterized in the present study. It was identiifed as Burkholderia sp. based on 16S rDNA sequence analysis, as wel as phenotypic and biochemical characterizations. This bacterium presented nitrogenase activity, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity and phosphate solubilizing ability;inhibited the growth of Sclerotinia sclerotiorum, Gibberel a zeae and Verticil ium dahliae;and produced smal quantities of indole acetic acid (IAA). In green house experiments, signiifcant increases in shoot height and weight, root length and weight, and stem diameter were observed on tomato plants in 30 d after inoculation with strain 7016. Result of 16S rDNA PCR-DGGE showed that 7016 survived in the rhizosphere of tomato seedlings. In the ifeld experiments, Burkholderia sp. 7016 enhanced the tomato yield and signiifcantly promoted activities of soil urease, phosphatase, sucrase, and catalase. Al these results demonstrated Burkholderia sp. 7016 as a valuable PGPR and a candidate of biofertilizer.

Promoting hepatic growth factor in the treatment of heavy type hepatitis and severe chronic hepatitis: a multicenter clinical study

BACKGROUND: The mortality rate of heavy type hepatitisis high. No special treatment is available except generaltreatment. This multicenter clinical study was designed toobserve the safety and efficacy of promoting hepatic growthfactor (PHGF) in the treatment of heavy type hepatitis andsevere chronic hepatitis.METHODS: 347 patients with heavy type hepatitis and 324with severe chronic hepatitis were subjected to administra-tion of 120 μg of PHGF per day for 4 weeks on the basis ofgeneral treatment. Those who were being effectively treat-ed would last additional 2 to 4 weeks. Blood routine, urineroutine, blood urea nitrogen (BUN), blood creatinine(Cr), blood ammonia, alpha fetoprotein (AFP), electro-lyte, alanine transaminase (ALT), aspartate transaminase(AST), serum total bilirubin (TBIL), serum direct biliru-bin (DBIL), prothrombin time activity (PTA), total pro-tein (TP) and albumin (ALB) were detected in the pa-tients before treatment, 2 weeks after treatment, and at theend of the treatment. Any side-effect would be recorded.RESULTS: In the patients with severe chronic hepatitis, thetotal effective rate of the treatment was 88. 9% The levelsof ALT, AST and TBIL decreased significantly (P<0.001),whereas those of PTA and ALB increased significantly (P <0.001), and the level of AFP increased slightly. In patientswith heavy type hepatitis, the total effective rate of thistreatment was 78.4%, and patients at different stage showeddifferent results. The total effective rates of patients withearly, medium and terminal stage heavy type hepatitis were89.9%, 84.8% and 27.5%, respectively. No severe side-effect was shown.CONCLUSION: PHGF is effective and safe in the treat-ment of patients with heavy type hepatitis and severe chro-nic hepatitis. But it should be administered early in patientswith heavy type hepatitis so as to get better curative effects.

Endophytic bacteria associated with endangered plant Ferula sinkiangensis K. M. Shen in an arid land： diversity and plant growth-promoting traits

Ferula spp. are traditional medicinal plants found in arid land. Large-scale excavation for extracting bioactive compounds from the plants in arid regions of Xinjiang over the last few years has, however, significandy decreased their distributions. Due to the urgent need for preservation of these plant resources, along with the need of searching for alternative source of the useful metabolites, it is important to screen the endophytic microbial resources associated with the plant Ferula sinkiangensis K. M. Shen. In the study, a total of 125 endophytic bacteria belonging to 3 phyla, 13 orders, 23 families, and 29 genera were isolated based on 16S rRNA gene sequencing data. Among the different isolates, three strains isolated from roots were potential novel species of the genera Porphyrobacter, Paracoccus and draycofatopsis. In this study, 79.4% and 57.1% of the total isolates were capable of producing indole-3-acetic acid （IAA） and siderophore, respectively. And, 40.6% of the strains inhibit the growth of fungal pathogen Afternaria alternata, 17.2% and 20.2% strains were positive for antagonism against Vertidllium dahlia 991 and V. dahlia 7, respectively. These results demonstrated that E sinkiangensis is a rich reservoir of endophytic bacterial resources with potential for production of biologically important functions such as plant growth-promoting factors.

Transcriptomic insights into growth promotion effect of Trichoderma afroharzianum TM2-4 microbial agent on tomato plants

Plant growth promoting fungi are receiving increased attention as valuable beneficial microorganisms in crop cultivation due to their capacity to produce bioactive substances,promote plant growth and enhance immune defense functions.In this study,a novel Trichoderma isolate,designated as TM2-4,was screened from healthy tomato rhizosphere soil and identified as Trichoderma afroharzianum.Culture filtrate of the isolate TM2-4 displayed obvious bioactive substance production and an evident effect in promoting tomato seed germination,with hypocotyl length,radical length and vigor index increased by 28.7,19.4 and 62.1%,respectively,after a 100-fold dilution treatment.To assess the promotion effect and related mechanism of isolate TM2-4,the plant biological indexes and gene expression profiles of tomato plants treated with or without T.afroharzianum TM2-4 microbial agent were investigated by greenhouse pot experiment and RNA sequencing.The results demonstrated that T.afroharzianum TM2-4 significantly promoted tomato plant growth in terms of plant height,dry weight,number of leaves per plant and root activity,through efficient colonization in the rhizosphere and root system of the plants.Transcriptome analyses identified a total of 984 differentially expressed genes in T.afroharzianum microbial agent inoculated tomato roots,which were mainly engaged in the biological process of phytohormone homeostasis,antioxidant activity,as well as metabolic pathways including phenylpropanoid biosynthesis and glutathione metabolism.These findings provide useful information for understanding the mechanism of isolate TM2-4 for tomato plant growth promotion,which would facilitate further development of T.afroharzianum TM2-4 microbial agent for use in vegetable crop production.

Efficiency of potassium-solubilizing Paenibacillus mucilaginosus for the growth of apple seedling

Chemical potassium(K)fertilizer is commonly used in apple(Malus domestica L.Borkh)production but K is easily fixed by soil,resulting in reduced K ferilizer utilization and wasted resources.K-solubilizing bacteria(KSB)can cost-effectively increase the soluble K content in rhizosphere soil.Therefore,the objectives were to select high-efficiency KSB from apple orchards under various soil management models and evaluate their effects on apple seedling growth.Maize(Zea maysL.)straw mulching(MSM)increased the total carbon(TC),total nitrogen(TN)and available potassium(AK)in the rhizosphere and improved fruit quality.The number of KSB in the rhizosphere soil of MSM was 9.5×10×CFU g1 soil,which was considerably higher than that in the other mulching models.Fourteen KSB strains were isolated with relative K solubilizing ability ranging from 17 to 30%,and five strains increased the dry weight per apple seedling.The most eficient strain was identified as Paenibacillus mucilaginosus through morphological observation and sequence analysis of 16S rDNA,named JGK.After inoculation,the colonization of JGK in soil decreased from 4.0 to 1.5×10×CFU g^-1 soil within 28 d.The growth of the apple seedlings and the K accumulation in apple plants were promoted by irigation with 50 mL JGK bacterial solution(1×10^9 CFU mL^-1),but there was no significant increase in the AK content of rhizosphere soil.High-performance liquid phase analysis(HPLC)data showed that the JGK metabolites contained phytohormones and organic acids.Hence,the JGK strain promoted the growth of two-month-old apple seedlings by stimulating function of the produced phytohormones and enhanced K solubility by acidification for apple seedling uptake.This study enriches the understanding of KSB and provides an effective means to increase the K utilization efficiency of apple production.

Pseudomonas sp.TK35-L enhances tobacco root development and growth by inducing HRGPnt3 expression in plant lateral root formation

Rhizosphere colonization is a key requirement for the application of plant growth-promoting rhizobacteria(PGPR)as a bioferilizer.Signaling molecules are often exchanged between PGPR and plants,and genes in plants may respond to the action of PGPR.Here,the luciferase luxAB gene was electrotransformed into Pseudomonas sp.strain TK35,a PGPR with an afinity for tobacco,and the labelled TK35(TK35-L)was used to monitor colonization dynamics in the tobacco rhizosphere and evaluate the effects of colonization on tobacco growth and root development.The transcript levels of the hydroxyproline rich glycoprotein HRGPnt3 gene,a lateral root induction indicator,in tobacco roots were examined by qPCR.The results showed that TK35-L could survive for long periods in the tobacco rhizosphere and colonize new spaces in the tobacco rhizosphere following tobacco root extension,exhibiting significant increases in root development,seedling growth and potassium accumulation in tobacco plants.The upregulation of HRGPnt3 transcription in the inoculated tobacco suggested that TK35-L can promote tobacco root development by upregulating the transcript levels of the HRGPnt3 gene,which promotes tobacco seedling growth.These findings lay a foundation for future studies on the molecular mechanism underlying the plant growth-promoting activities of PGPR.Futhermore,this work provided an ideal potential strain for biofertilizer production.

Selection,Identification and Growth Promotion of Inorganic Phosphorus-dissolving Bacterial Strains in Rhizosphere of Trifolium repens

[Objective] The aim was to select and identify inorganic phosphorus-dissolving bacteria in rhizosphere of Trifolium repens,and to research related effects of growth promotion.[Method] Phosphate solubilizing bacteria in rhizosphere of Trifolium repens in Guizhou Province were separated and selected to determine its ability of phosphate solubilizing and IAA secretion,and growth promotion effect.[Result] Phosphate solubilizing bacteria were multiple and varied in rhizosphere of Trifolium repens;solubilizing quantities of phosphorus from calcium phosphate by RW2,RW6 and RW18 were 337.39,447.45 and 462.03 μg/ml;solubilizing quantity was none of linear relation with organic acid;RW2 proved the one secreted most IAA at 12.69 μg/ml,followed by RW18 at 12.34 μg/ml;the three strains were all of Leclercia sp.,but were of none pathogenicity for seedlings of Trifolium repens,instead,a kind of growth promotion was found.Detailedly,RW18 was most effective in growth promotion for Trifolium repens and plant height,root length and weight,and aboveground biomass increased by 110.98%,9.17%,46.17% and 2% respectively.Hence,RW18 is of great potential.[Conclusion] The research provides scientific references for developing phosphate solubilizing bacteria and compound inoculation and develops a novel way to relieve barren soils,save phosphorus resource,reduce environment pollution,and guarantee sustainable development of agriculture and animal husbandry.

MEK AND p38 MAPK-DEPENDANT PATHWAYS ARE INVOLOVED IN THE POSITIVE EFFECT OF INTERLEUKIN-6 ON HUMAN GROWTH HORMONE GENE EXPRESSION IN RAT MtT/S SOMATOTROPH CELLS

Objective To investigate the effect of interleukin-6(IL-6)on the human growth hormone(hGH)gene expression in a rat somatotropic pituitary cell line MtT/S.Methods The plasmids containing various lengths of hGH gene 5'-promoter fragments were constructed.Stably transfected MtT/S cells were created by cotransfecting the above plasmids and pcDNA3.1(+)with DMRIE-C transfection reagent.After the administration of these cells with IL-6 and/or various inhibitors of signaling transduction pathways,the luciferase activities in MtT/S cells lysis were assayed to demonstrate the effects of IL-6 on hGH gene promoter activity and possibly involved mechanism.Results The 103 U/mL IL-6 stimulated GH secretion and synthesis,and promoted the 5'-promoter activity of GH gene in stably transfected MtT/SGL cells with the action of 1.69 times above the control.Among inhibitors of signaling transduction pathways,mitogen-activated protein kinase kinase(MAPKK/MEK)inhibitor PD98059(40 μmol/L)and p38 mitogen-activated protein kinase(MAPK)inhibitor SB203580(5 μmol/L)completely blocked the stimulatory effect of IL-6.Western blot analysis further confirmed the activation of phosphorylated MEK and p38 MAPK in MtT/SGL cells.Neither over-expression of Pit-1 nor inhibition of Pit-1 expression affected IL-6 induction of hGH promoter activity.A series of deletion constructs of hGH promoter were created to identify the DNA sequence that mediated the effect of IL-6.The results showed that the stimulatory effect of IL-6 was abolished following deletion of the-196 to-132 bp fragment.Conclusions IL-6 promotes GH secretion and synthesis by rat MtT/S somatotroph cells.The stimulatory effect of IL-6 on hGH gene promoter appears to require the activation of MEK and p38 MAPK,and a fragment of promoter sequence that spans the-196 to-132 bp of the gene,but may be unlinked with Pit-1 protein.

EFFECT OF INTERLEUKIN-1β ON GROWTH HORMONE GENE EXPRESSION AND ITS POSSIBLE MOLECULAR MECHANISM IN RAT MtT/S SOMATOTROPH CELLS

Objective To elucidate the effect of interleukin-1β （IL- 1β） on human growth hormone （hGH） gene expression in a rat somatotropic pituitary cell line MtT/S. Methods Stably transfected MtT/S cells were firstly established by transfecting 484-Lucl plasmid which contained hGH gene promoter --484 to ＋30 bp and luciferase reporter gene. The effect of IL-1β on hGH gene expression was determined by assaying the luciferase activities. RT-PCR method was also used to determine whether IL-1 recepor mRNA was expressed in MtT/S cells. Results The 10^3 U/mL IL-1β stimulated secretion and synthesis of GH, and promoted the 5＇-promoter activity of GH gene in stably transfected MtT/SGL cells with the action of 1.38 times above the control. Among inhibitors of signaling transduction pathways, mitogen-activated protein kinase kinase （MAPKK/MEK） inhibitor PD98059 （40 μmol/L） and p38 mitogen-activated protein kinase （MAPK） inhibitor SB203580 （5 μmol/L） completely blocked the stimulatory effect of IL-1μ, and phosphatidylinositol-3-kinase （PI3-K） inhibitor LY294002 partly abolished the effect of IL-1μ. Western blot analysis further confirmed the activation of phosphorylated MEK and p38 MAPK in MtT/SGL cells. Neither over-expression of Pit- 1 nor inhibition of Pit- 1 expression affected induction of hGH promoter activity by IL-1μ. A series of deletion constructs of hGH promoter were created to identify the DNA sequence that mediated the effect of IL-1β, and results showed that the stimulatory effect of IL-1β was abolished following deletion of the --196 to -- 132 bp fragment. Conclusions IL-1β promotes GH secretion and synthesis in rat MtT/S somatotroph cells. The stimulatory effect of IL-1β on hGH gene promoter appears to require the activation of MEK, p38 MAPK, PI3-K, and a fragment of promoter sequence that spans the -196 to -132 bp of the gene, but it may be unlinked with Pit-1 protein.