Retinol dehydrogenase, RDH1l, is essential for the heart development and cardiac performance in zebrafish / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Retinoic acid (RA) is a potent signaling molecule that plays pleiotropic roles in patterning, morphogenesis, and organogenesis during embryonic development. The synthesis from retinol (vitamin A) to retinoic acid requires two sequential oxidative steps. The first step involves the oxidation of retinol to retinal through the action of retinol dehydrogenases. Retinol dehydrogenases1l (RDH1l) is a novel zebrafish retinol dehydrogenase. Herein we investigated the role of zebrafish RDH1l in heart development and cardiac performance in detail.</p><p><b>METHODS</b>RDH1l specific morpholino was used to reduce the function of RDH1l in zebrafish. The gene expressions were observed by using whole mount in situ hybridization. Heart rates were observed and recorded under the microscope from 24 to 72 hours post fertilization (hpf). The cardiac performance was analyzed by measuring ventricular shortening fraction (VSF).</p><p><b>RESULTS</b>The knock-down of RDH1l led to abnormal neural crest cells migration and reduced numbers of neural crest cells in RDH1l morphant embryos. The reduced numbers of cardiac neural crest cells also can be seen in RDH1l morphant embryos. Furthermore, the morpholino-mediated knock-down of RDH1l resulted in the abnormal heart loop. The left-right determining genes expression pattern was altered in RDH1l morphant embryos. The impaired cardiac performance was observed in RDH1l morphant embryos. Taken together, these data demonstrate that RDH1l is essential for the heart development and cardiac performance in zebrafish.</p><p><b>CONCLUSIONS</b>RDH1l plays a important role in the neural crest cells development, and then ultimately affects the heart loop and cardiac performance. These results show for the first time that an enzyme involved in the retinol to retinaldehyde conversion participate in the heart development and cardiac performance in zebrafish.</p>

Effect of Tbx1 knock-down on cardiac performance in zebrafish / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Tbx1 is the major candidate gene for DiGeorge syndrome (DGS). Similar to defects observed in DGS patients, the structures disrupted in Tbx1(-/-) animal models are derived from the neural crest cells during development. Although the morphological phenotypes of some Tbx1 knock-down animal models have been well described, analysis of the cardiac performance is limited. Therefore, myocardial performance was explored in Tbx1 morpholino injected zebrafish embryos.</p><p><b>METHODS</b>To elucidate these issues, Tbx1 specific morpholino was used to reduce the function of Tbx1 in zebrafish. The differentiation of the myocardial cells was observed using whole mount in situ hybridization. Heart rates were observed and recorded under the microscope from 24 to 72 hours post fertilization (hpf). The cardiac performance was analyzed by measuring ventricular shortening fraction and atrial shortening fraction.</p><p><b>RESULTS</b>Tbx1 morpholino injected embryos were characterized by defects in the pharyngeal arches, otic vesicle, aortic arches and thymus. In addition, Tbx1 knock down reduced the amount of pharyngeal neural crest cells in zebrafish. Abnormal cardiac morphology was visible in nearly 20% of the Tbx1 morpholino injected embryos. The hearts in these embryos did not loop or loop incompletely. Importantly, cardiac performance and heart rate were reduced in Tbx1 morpholino injected embryos.</p><p><b>CONCLUSIONS</b>Tbx1 might play an essential role in the development of pharyngeal neural crest cells in zebrafish. Cardiac performance is impaired by Tbx1 knock down in zebrafish.</p>

Effects of folic acid on the development of heart of zebrafish / 中华儿科杂志

<p><b>OBJECTIVE</b>To construct the folic acid deficient model in zebrafish and observe the abnormal cardiac phenotypes, to find the optimal period for supplementing folic acid that can most effectively prevent the heart malformation induced by folic acid deficiency, and to investigate the possible mechanisms by which folic acid deficiency induces malformations of heart.</p><p><b>METHOD</b>The folic acid deficient zebrafish model was constructed by using both the folic acid antagonist methotrexate (MTX) and knocking-down dhfr (dihydrofolate reductase gene). Exogenous tetrahydrofolic acid rescue experiment was performed. Folic acid was given to folic acid deficient groups in different periods. The percent of cardiac malformation, the cardiac phenotypes, the heart rate and the ventricular shortening fraction (VSF) were recorded. The out flow tract (OFT) was observed by using fluorescein micro-angiography. Whole-mount in situ hybridization and real-time PCR were performed to detect vmhc, amhc, tbx5 and nppa expressions.</p><p><b>RESULT</b>About (78.00 ± 3.74)% embryos in MTX treated group and (68.00 ± 6.32)% embryos in dhfr knocking-down group had heart malformations, including the abnormal cardiac shapes, the hypogenesis of OFT and the reduced heart rate and VSF. Giving exogenous tetrahydrofolic acid rescued the above abnormalities. Given the folic acid on 8 - 12 hours post-fertilization (hpf), both the MTX treated group (20.20% ± 3.77%) and dhfr knocking-down group (43.40% ± 4.51%) showed the most significantly reduced percent of cardiac malformation and the most obviously improved cardiac development. In folic acid deficient group, the expressions of tbx5 and nppa were reduced while the expressions of vmhc and amhc appeared normal. After being given folic acid to MTX treated group and dhfr knocking-down group, the expressions of tbx5 and nppa were increased.</p><p><b>CONCLUSIONS</b>The synthesis of tetrahydrofolic acid was decreased in our folic acid deficient model. Giving folic acid in the middle period, which is the early developmental stage, can best prevent the abnormal developments of hearts induced by folic acid deficiency. Folic acid deficiency did not disrupt the differentiations of myosins in ventricle and atrium. The cardiac malformations caused by folic acid deficiency were related with the reduced expressions of tbx5 and nppa.</p>

Progesterone promotes propagation and viability of mouse embryonic stem cells / 生理学报

It has been known that estrogen-17beta stimulates proliferation of mouse embryonic stem (mES) cells. To explore the function of another steroid hormone progesterone, we used MTT method and BrdU incorporation assay to obtain growth curves, clone forming assay to detect the propagation and viability of individual mES cells, Western blot to test the expression of ES cell marker gene Oct-4, fluorescence activated cell sorter (FACS) to test cell cycle, and real-time PCR to detect the expressions of cyclins, cyclin-dependent kinases and proto-oncogenes. The results showed that progesterone promoted proliferation of mES cells. The number of clones was more in progesterone-treated group than that in the control group. The expression of pluripotency-associated transcriptional factor Oct-4 changed little after progesterone treatment as shown by Western blot, indicating that most of mES cells were in undifferentiated state. The results of FACS proved that progesterone promoted DNA synthesis in mES cells. The proportion of mES cells in S+G(2)/M phase was higher in progesterone-treated group than that in the control group. Cyclins and cyclin-dependent kinases, as well as proto-oncogenes (c-myc, c-fos) were up-regulated when cells were treated with progesterone. The results obtained indicate that progesterone promotes propagation and viability of mES cells. The up-regulation of cell cycle-related factors might contribute to the function of progesterone.

Effect of external retinoic acid on Tbx1 gene during zebrafish embryogenesis / 中华儿科杂志

<p><b>OBJECTIVE</b>DiGeorge/del22q11 syndrome is one of the most common genetic causes of outflow tract and aortic arch defects in human. DiGeorge/del22q11 is thought to involve an embryonic defect restricted to the pharyngeal arches and the corresponding pharyngeal pouches. Previous studies have evidenced that retinoic acid (RA) signaling is definitely indispensable for the development of the pharyngeal arches. Tbx1, one of the T-box containing genes, is proved to be the most attractive candidate gene for DiGeorge/del22q11 syndrome. However, the interaction between RA and Tbx1 has not been fully investigated. Exploring the interaction will contribute to discover the molecular pathways disrupted in DiGeorge/del22q11 syndrome, and will also be essential for understanding genetic basis for congenital heart disease. It now seems possible that genes and molecular pathways disrupted in DiGeorge syndrome will also account for some isolated cases of congenital heart disease. Accordingly, the present study aimed to extensively study the effects of external RA on the cardiac development and Tbx1 expression during zebrafish embryogenesis.</p><p><b>METHODS</b>The chemical genetics approach was applied by treating zebrafish embryos with 5 x 10(-8) mol/L RA and 10(-7) mol/L RA at 12.5 hour post fertilization (hpf). The expression patterns of Tbx1 were monitored by whole-mount in situ hybridization and quantitative real-time RT-PCR, respectively.</p><p><b>RESULTS</b>The zebrafish embryos treated with 5 x 10(-8) mol/L RA and 10(-7) mol/L RA for 1.5 h at 12.5 hpf exhibited selective defects of abnormal heart tube. The results of whole-mount in situ hybridization with Tbx1 RNA probe showed that Tbx1 was expressed in cardiac region, pharyngeal arches and otic vesicle during zebrafish embryogenesis. RA treatment led to a distinct spatio-temporal expression pattern for Tbx1 from that in wild type embryo. The real-time PCR analysis showed that Tbx1 expression levels were markedly reduced by RA treatment. Tbx1 expression in the pharyngeal arches and heart were obviously down regulated compared to the wild type embryos. In contrast to 5 x 10(-8) mol/L RA-treated groups, 10(-7) mol/L RA caused a more severe effect on the Tbx1 expression level.</p><p><b>CONCLUSION</b>These results suggested that there was a genetic link between RA and Tbx1 during development of zebrafish embryo. RA could produce an altered Tbx1 expression pattern in zebrafish. RA may regulate the Tbx1 expression in a dose-dependant manner. RA could represent a major epigenetic factor to cause abnormal expression of Tbx1, secondarily, disrupt the pharyngeal arch and heart development.</p>

Folic acid antagonist methotrexate causes the development malformation of heart and down-regulates the BMP2b and HAS2 expressions in zebrafish / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To study the effect of methotrexate (MTX), a folic acid antagonist which can lead to folic acid deficient, on the cardiac development and on the expressions of BMP2b and HAS2 in zebrafish.</p><p><b>METHODS</b>The zebrafish embryos at 6-48 hrs post fertilization (hpf) were treated with various concentrations of MTX (0.5 x 10(-3), 1.0 x 10(-3) and 2.0 x 10(-3) M). At 48 hpf, the percentage of cardiac malformation and heart rate were recorded. The zebrafish embryos at 6-10 hpf treated with 1.5 x 10(-3) M MTX were used as the MTX treatment group. At 24 and 48 hpf the cardiac morphology was observed under a microscope. The expressions of BMP2b and HAS2 in zebrafish were detected by in situ antisense RNA hybridization and real-time PCR.</p><p><b>RESULTS</b>6-12 hpf, the early embryonic developmental stage, was a sensitive period that MTX affected cardiac formation of zebrafish. The retardant cardiac development and the evidently abnormal cardiac morphology was found in the MTX treatment group. The results of in situ antisense RNA hybridization showed that the expressions of BMP2b and HAS2 in the zebrafish heart were reduced in the MTX treatment group at 36 and 48 hpf. The real-time PCR results demonstrated that the BMP2b expression decreased at 12, 24, 36 and 48 hpf, and that the HAS2 expression decreased at 24, 36 and 48 hpf in the treatment group compared with the control group without MTX treatment.</p><p><b>CONCLUSIONS</b>The inhibition of folic acid function may affect cardiac development of early embryos, resulting in a retardant development and a morphological abnormality of the heart in zebrafish, possibly by down-regulating the expressions of BMP2b and HAS2.</p>

Effect of dihydrofolate reductase gene knock-down on the expression of heart and neural crest derivatives expressed transcript 2 in zebrafish cardiac development / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Folic acid is very important for embryonic development and dihydrofolate reductase is one of the key enzymes in the process of folic acid performing its biological function. Therefore, the dysfunction of dihydrofolate reductase can inhibit the function of folic acid and finally cause the developmental malformations. In this study, we observed the abnormal cardiac phenotypes in dihydrofolate reductase (DHFR) gene knock-down zebrafish embryos, investigated the effect of DHFR on the expression of heart and neural crest derivatives expressed transcript 2 (HAND2) and explored the possible mechanism of DHFR knock-down inducing zebrafish cardiac malformations.</p><p><b>METHODS</b>Morpholino oligonucleotides were microinjected into fertilized eggs to knock down the functions of DHFR or HAND2. Full length of HAND2 mRNA which was transcribed in vitro was microinjected into fertilized eggs to overexpress HAND2. The cardiac morphologies, the heart rates and the ventricular shortening fraction were observed and recorded under the microscope at 48 hours post fertilization. Whole-mount in situ hybridization and real-time PCR were performed to detect HAND2 expression.</p><p><b>RESULTS</b>DHFR or HAND2 knock-down caused the cardiac malformation in zebrafish. The expression of HAND2 was obviously reduced in DHFR knock-down embryos (P < 0.05). Microinjecting HAND2 mRNA into fertilized eggs can induce HAND2 overexpression. HAND2 overexpression rescued the cardiac malformation phenotypes of DHFR knock-down embryos.</p><p><b>CONCLUSIONS</b>DHFR plays a crucial role in cardiac development. The down-regulation of HAND2 caused by DHFR knock-down is the possible mechanism of DHFR knock-down inducing the cardiac malformation.</p>

Preparation and characterization of PLGA microspheres containing a staphylokinase variant (K35R) / 药学学报

<p><b>AIM</b>To produce poly (lactic-co-glycolic acid) (PLGA) microspheres, containing a staphylokinase variant (K35R, DGR) with reduced immunogenecity and antiplatelet aggregation activities, which allowed the preservation of protein stability during both particle processing and drug release.</p><p><b>METHODS</b>DGR-loaded microspheres were fabricated using a double emulsion-solvent evaporation technique. The effects of preparative parameters, such as stirring rate, polymer concentration, and the excipients of both internal and external aqueous phase (W2), on DGR encapsulation efficiency and microsphere characteristics were investigated. In vitro and in vivo release of DGR were conducted and the cause for instability of DGR during release was also investigated.</p><p><b>RESULTS</b>Moderate ultrasonic treatment of aqueous DGR/dichloromethane mixtures caused approximately. Eighty four per cent DGR denaturation. However, the activity recovery of DGR almost amounted to 100% when 2% polyvinyl alcohol (PVA) was addled into the aqueous phase. It was found that NaCl in the external water phase significantly increased DGR encapsulation efficiency. Furthermore, NaCl in the external water phase played a role in determining size and surface morphology of microsphere. In vitro release test showed a burst release of DGR from microspheres, followed by sustained release of 50% total activity over 15 days. In vivo experiments showed that DGR released from microspheres sustained 5 days. Denaturation of DGR within microspheres might be resulted from acidic microclimate.</p><p><b>CONCLUSION</b>The stability of DGR was effectively protected during microencapsulation and a relatively high encapsulation efficiency of DGR was obtained. PLGA microspheres could be an effective carrier for DGR.</p>

Cloning, expression and biological characterization of hTFPI-2 gene / 中华血液学杂志

<p><b>OBJECTIVE</b>To clone the human tissue factor pathway inhibitor-2 (hTFPI-2) gene and express it by using prokaryotic expression system.</p><p><b>METHODS</b>The hTFPI-2 coding region was obtained by RT-PCR from human placenta total RNA. The coding fragment was then inserted into prokaryotic expression vector pET19b and expressed in E. coli BL21 by IPTG induction. The produced inclusion bodies were dissolved by denaturalizing chemicals, purified by ion exchange chromatograph, and refolded in air to form proper disulfide bonds. Chromogenic and gelatin zymography methods were used to evaluate the inhibiting effects of hTFPI-2 on trypsin, plasmin and MMPs individually. The inhibitory activity of hTFPI-2 on fabrisarcoma was investigated by matrigel.</p><p><b>RESULTS</b>The coding fragment of hTFPI-2 was cloned successfully and the protein was expressed as inclusion bodies which account for 20% - 30% of total host protein. The refolded hTFPI-2 could inhibit the invasive ability of fibrisarcoma HT-1080 as well as activity of plasmin, trypsin and MMPs.</p><p><b>CONCLUSIONS</b>The activated hTFPI-2 is obtained by using prokaryotic expressed system effectively.</p>

Fermentation, purification and identification of recombinant RGD-Hirudin / 生物工程学报

Recombinant RGD-Hirudin ( r-RGD-Hirudin ) has double functions: anti-thrombin activity and anti-platelet aggregation activity. To identify these functions, the expression plasmid, RGD-Hirudin-pPIC9K, was constructed by inserting cDNA of RGD-hirudin in yeast expression vector pPIC9K. The high expression clone was gained after screening. This clone was fermented for 3 days. The r-RGD-hirudin was secreted into the culture. It was ultra-filtrated from culture supernatant, then after gel filtration chromatography and anion exchange chromatography, the purified r-RGD-hirudin was gained. Its purity was larger than 97% and its specific activity was 12 000 ATU/mg. The yield per liter culture of purified r-RGD-hirudin was 1 g and overall recovery yield was more than 75% . The purified r-RGD-hirudin was identified by reductive SDS-PAGE, anti-thrombin activity assay, anti-platelet aggregation assay, LC/MS and isoelectrofocusing assay. It is proved that r-RGD-Hirudin is ramification of wt-Hirudin and it has anti-thrombin activity and anti-platelet aggregation activity.

Preparation and functional study of an adenovirus vector expressing human plasminogen kringle 5 gene / 生物工程学报

Tumor angiogenesis plays a pivotal role in the progress of tumor. Among the various endogenous angiogenic inhibitors discovered, the human plasminogen kringle 5 (K5) has been demonstrated to be a potential inhibitor of the proliferation and migration of vascular endothelial cells in vitro. The replication-incompetent adenovirus (Ad) vector Adeno-X-CMV-K5 (Ad-K5) (where CMV is cytomegalovirus) was constructed and its antiangiogenic effect was tested on vascular endothelial cell and tumor cell. For the construction, the K5 cDNA was fused in-frame with human plasminogen signal sequence and inserted into the eukaryotic expression vector pcDNA3 to form pcDNA3K5. The recombinant plasmid was subcloned into the shuttle plasmid pShuttle under the control of the constitutive CMV immediate-early promoter. The plasmid carrying the cDNA for K5 (pShuttleKS) was then recombined with the Adeno-X viral DNA and transformed into E. coli DH5alpha. The resultant recombinant plasmid pAd-K5 was transfected into human embryonic kidney (HEK) 293 cells with liposome. The adenovirus expressing human plasminogen kringle 5 (Ad-K5) was successfully packaged and propagated in 293 cells, as detected by the cytopathic effect (CPE) on the cells, and the viral titer in the supernatant was 5 x 10(8) pfu/mL by plaque assay. Both human umbilical vein endothelial cell line ECV304 and human breast carcinoma cell line MDA-MB-231 were infected with Ad-K5 and Ad-LacZ, which was used the negative control, and assayed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Compared with uninfected control and Ad-LacZ infected control, Ad-K5 infected group at 80 MOI (multiplicity of infection) significantly inhibited ECV304 proliferation; the difference between uninfected control and Ad-LacZ infected control was not significant. In contrast, there was no significant difference in the proliferation of MDA-MB-231 among all the treatments. In addition, the Ad-K5 at 100 MOI inhibited the differentiation and tube formation of ECV304 on ECMatrix gel. These results suggested that the recombinant replication-defective Adenovirus expressing human plasminogen kringle 5 inhibited the proliferation, differentiation and tube formation of ECV304 and had no effect on the proliferation of MDA-MB-231. Adenovirus mediated human plasminogen kringle 5 gene therapy may be a potential treatment of cancer through angiogenesis inhibition.

Preliminary study of ALK3 downstream genes related to ventricular septum defect / 生物工程学报

To investigate the function of ALK3 gene, the gene regulation and the signaling pathway related to ventricular septum defect during heart development. The model mice with ALK3 gene knock-out via alpha-MHC-Cre/lox P system were bred. The mRNA expression level of control group was compared with that of experiment group and ALK3 downstream genes were screened using PCR-select cDNA subtraction microarray. The mRNA of control group was extracted from E11.5 normal mouse hearts, and that of experiment group, from E11.5 hearts of mice with alpha-MHC Cre(+/-) ALK3(F/+) genotype. It was found that the mice with ALK3 gene knock-out produced heart defects involving the interventricular septum. The platelet-activating factors acetylhydrolase and the transcription factor Pax-8 and so on, were down-regulated. However, the Protein Tyrosine Kinase (PTK) of Focal Adhesion Kinase (FAK) subfamily and beta subtype protein 14-3-3 were up-regulated in the alpha-MHC Cre(+/-) ALK3(F/-) mice. These data provide support that ALK3 gene played an important role during heart development. The platelet-activating factors acetylhydrolase and Pax-8 genes could be important ALK3 downstream genes in the BMP signaling pathway during interventricular septum development. PTK and beta subtype protein 14-3-3 might be regulatory factors in this pathway.

A study on myocardial Pax-8 gene / 中华儿科杂志

<p><b>OBJECTIVE</b>Conventional deletion of ALK3, also termed as bone morphogenetic protein (BMP) receptor IA, in mice might result in early embryonic lethality. To investigate the function of ALK3 in cardiac development, the cardiac-specific deletion of ALK3 in mice was made by Dr. Schneider, using Cre recombinase driven by the alpha-MHC promoter that Dr. Fukushipe worked out. Such specific deletion of ALK3 caused death in mid-gestation with defects in the trabeculae, interventricular septum, and endocardial cushion. Since ALK3 is not a cardiac-specific gene, it is extremely important to identify ALK3 downstream genes.</p><p><b>METHODS</b>Alpha-MHC Cre+/-, ALK3 F/- and alpha-MHC Cre+/-, ALK3 F/+ embryos were obtained after 20 alpha-MHC Cre+/-, ALK3 +/- mice and 20 ALK3 F/F mice were mating. The ALK3 downstream genes were screened using microarray made in Germany that could identify 25000 genes in mouse. Two populations of mRNA, one derived from the embryonic heart (11.5 days) of alpha-MHC Cre+/-, ALK3 F/- mice, and the other derived from the alpha-MHC Cre+/-, ALK3 F/+ mice, were compared. Cardiac-specific ALK3 downstream genes were identified using real time quantitative RT-PCR and in situ hybridization.</p><p><b>RESULTS</b>The expression of 12 genes, such as Pax-8 and Hox-3.5 were down-regulated in alpha-MHC Cre+/-, ALK3 F/- mouse heart. The expression of 16 genes including Ras-related protein Rab-5b and EPS-8 protein was up-regulated in the group of alpha-MHC Cre+/-, ALK3 F/-. It was found that the Box protein Pax-8 gene was down-regulated by 7.1 fold (P < 0.001) in the alpha-MHC Cre+/-, ALK3 F/- mice by real time quantitative RT-PCR. It was also revealed that the Box protein Pax-8 gene was expressed stronger in alpha-MHC Cre+/-, ALK3 F/+ than alpha-MHC Cre+/-, ALK3 F/- E11.5 days mouse heart by means of in situ hybridization.</p><p><b>CONCLUSION</b>The Box protein Pax-8 gene is an important and cardiac-specific ALK3 downstream gene in the BMP signaling pathway during inter-ventricular septum development.</p>

The renaturation and purification of RGD-staphylokinase by gel filtration / 生物工程学报

A recombinant RGD-Staphylokinase(RGD-Sak) with thrombolytic and anti-thrombolytic bifunction was expressed in E. coli. The expression product accumulates as inclusion bodies. In order to obtain active molecule, the RGD-Sak in the inclusion body should be denatured and then renatured. The renaturation of RGD-Sak was performed by gel filtration. Comparing with the traditional way of dilution renaturation, gel filtration way is better than the traditional one, since there are some advantages, such as simple processing, high recovery, low cost and higher purity after renaturation, After renaturation, RGD-Sak was purified by Q-Sepharose FF, and the purity was more than 95%. Analysis of CD spectra showed that the final product from the two renaturation ways have similar CD spectra. It was demonstrated that RGD-Sak molecules proceeded correct refolding through gel filtration or dilution renaturation process.