内蛋白子及其功能

内蛋白子及其功能白玉明，袁静明（山西大学生命科学系，太原０３０００６）关键词内蛋白子，蛋白质剪接，内蛋白子归巢１．内蛋白子内蛋白子（ｉｎｔｅｉｎ）是由Ｐｅｒｌｅｒ等［１］于１９９４年正式提出的与蛋白质剪接（ｐｒｏｔｅｉｎｓｐｌｉｃｉｎｇ）有关的一个专...

利用内蛋白子剪切功能一步纯化重组人神经营养因子-3

将人神经营养因子 - 3(h NT3)基因插入含内蛋白子 -几丁质结合区 (Intein- CBD)片段的质粒p TXB1的多克隆位点 ,构建成重组子 p TXB- h NT3,随后转化入 E.coli 2 566并进行融合表达 .表达产物包涵体经 8mol/ L脲变性 ,并在 GSH,GSSG存在下复性 .复性后的融合蛋白经几丁质珠亲和柱吸附 .待洗涤杂蛋白后 ,加入 50 mmol/ L DTT在 4℃或 2 5℃进行剪切反应 48h,再用缓冲液洗脱 ,即得 h NT3.SDS- PAGE分析表明 ,h NT3达电泳纯 .其分子量约为 1 4 k

用温度诱导融合表达含内蛋白子的人神经营养因子-3

将重组质粒 pTXB NT3(6 9kb)与载体 pJLA50 3(4 9kb)分别用Nde 1/BamH 1双酶切 ,然后将前者的人神经营养因子 3 内蛋白子 几丁质结合区 (hNT3 in tein CBD)DNA片段插入后者载体中 ,构建成一个含内蛋白子的温度诱导型表达载体pLZY0 1。经转化后 ,工程菌E coliBL2 1/ pLZY0 1在LB培养基中培养 ,表达产物约为4 2kD的hNT3 intein CBD融合蛋白 ,经DTT不完全化学拆除后 ,可得约 15kD的hNT3,2 7kD的intein CBD及 4 2kD的融合蛋白 ,产物经鸡胚背根神经节测定其生物活性 ,融合蛋白在 80ng ,hNT3在 2 5ng时能较好地促进神经纤维的伸长。

Engineering The Neck Hinge Reshapes The Processive Movement of Kinesin-3

Objective In kinesin-3,the neck coil correlates with the following segments to form an extended neck that contains a characteristic hinge diverse from a proline in KIF13B to a long flexible linker in KIF1A.The function of this neck hinge for controlling processive movement,however,remains unclear.Methods We made a series of modifications to the neck hinges of KIF13B and KIF1A and tested their movement using a single-molecule motility assay.Results In KIF13B,the insertion of flexible residues before or after the proline differentially impacts the processivity or velocity,while the removal of this proline increases the both.In KIF1A,the deletion of entire flexible neck hinge merely enhances the processivity.The engineering of these hinge-truncated necks of kinesin-3 into kinesin-1 similarly boosts the processive movement of kinesin-1.Conclusion The neck hinge in kinesin-3 controls its processive movement and proper modifications tune the motor motility,which provides a novel strategy to reshape the processive movement of kinesin motors.

Reconstruction of HP Intein with Overlap-extension PCR

[Objective] This study aimed to reconstruct the HP intein by overlap-exten- sion PCR. [Method] Several primers were designed according to the principle of overlap-extension PCR that the repeat sequences were overlapped and served as the template to the other DNA strand in amplification. Then, several rounds of over- lap PCR reaction were conducted to mutate the four cysteines in the HP intein into serines, and introduce a linker sequence containing a tag for product detection and purification. [Result] DNA sequencing analysis proved that the four cysteines in the HP intein were successfully mutated into serines; the PCR precursor fragments were also rejoined into an intact HP gene fragment, without introducing any other unex- pected mutation; the DNA linker of 46 bp was successfully inserted into the de- signed HP gene sequences, without any mutation and base pair mismatch. [Conclu- sion] The HP intein was rapidly reconstructed by overlap-extension PCR in this study, which not only expands the application of overlap PCR in protein engineering, but also provides a simple, efficient and highly accurate tool for the reconstruction and modification of intein.

Sequence Analysis of Polymorphic Fragments in the Third Intron of Porcine H-FABP Gene

[ Objective] The aim of this study was to provide a theoretical basis for exploring the major genes affecting intramuscular fat （IMF） deposition. [Method] Taking 383 pigs from five breeds including Mashen Pig, Large White Pig, Landrace, Duroc and Shanxi White Pig as the experimental animals, polymorphisms of partial fragments in the third intron of porcine H-FABP gene were detected by PCR-SSCP method, and then the polymorphic fragments were sequenced. [ Result] Two alleles, designated as A and B, were found at the locus 346 in the third intron of porcine H-FABP gene, and the mutation was caused by a A→G substitution. [ Conclusion] A polymorphic locus was discovered in the third intron of porcine H-FABP gene in this experiment, laying a foundation for the further study on the relationship between H-FABP gene and IMF content.

Sustained Contraction of Isolated Rabbit Thoracic Aortic Rings in Endothelial-dependent Manner Induced by βγ-CAT

In vertebrates, non-lens βγ-crystallins are widely expressed in various tissues and their functions are not well known. The molecular mechanisms of trefoil factors （TFFs）, which involved in mucosal healing and tumorigenesis, have remained elusive. βγ-CAT is a novel multifunctional protein complex of non-lens βγ-crystallin and trefoil factor from frog skin secretions. Here we report that βγ-CAT could induce sustained contraction of isolated rabbit aortic rings in dosage （2-35nmol/L） and endothelium dependent manners （P〈0.01 ）. In addition, in situ immunofluorescence indicated that positive TNF-α signals were mainly detected at the endothelial cell layer of βγ-CAT （25nmol/L） treated rings. Furthermore, βγ-CAT induced primary cultured rabbit thoracic aortic endothelial cells （RAECs） rapidly to release TNF-α. After βγ-CAT （25nmol/L） treated for 10 and 30min, the levels of the endothelial cells released TNF-ct were 34.17±5.10 pg/mL and 98.01±4.67 pg/mL （P〈0.01）, respectively. In conclusion, βγ-CAT could induce sustained contraction of isolated aortic rings, and the contractile effect might be partially explained by the release of TNF-α. These findings will give new insight into understanding the functions and physiological roles of non-lens βγ-crystallins and trefoil factors.

Migration-associated secretion of melanoma inhibitory activity at the cell rear is supported by KCa3.1 potassium channels

Malignant melanoma, characterized by invasive local growth and early formation of metastases, is the most aggressive type of skin cancer. Melanoma inhibitory activity （MIA）, secreted by malignant melanoma cells, interacts with the cell adhesion receptors, integrins a4131 and 05131, facilitating cell detachment and promoting formation of me- tastases. In the present study, we demonstrate that MIA secretion is confined to the rear end of migrating cells, while in non-migrating cells MIA accumulates in the actin cortex. MIA protein takes a conventional secretory pathway including coat protein complex I （COPI）- and coat protein complex II （COPII）-dependent protein transport to the cell periphery, where its final release depends on intracellular Ca2＋ ions. Interestingly, the Ca2＋-activated K＋-channel, subfamily N, member 4 （KCa3.1）, known to be active at the rear end of migrating cells, was found to support MIA secretion. Secretion was diminished by the specific KCa3.1 channel inhibitor TRAM-34 and by expression of dominant- negative mutants of the channel. In summary, we have elucidated the migration-associated transport of MIA protein to the cell rear and also disclosed a new mechanism by which KCa3.1 potassium channels promote cell migration.

Molecular evidence suggests that the enigmatic Sulawesi endemic Geomalia heinrichi belongs in the genus Zoothera (Turdidae, Aves)

The taxonomic status of the Sulawesi endemic Geomalia heinrichi has long been debated, and it has variously been treated as a babbler (Timaliidae) or a turdid (Turdidae). We estimated the phylogeny of 43 taxa in the family Turdidae based on the mitochondrial cytochrome b gene and the nuclear myoglobin intron 2 and ornithine decarboxylase introns 6–7. Geomalia heinrichi was shown to be part of the Zoothera clade with high support. We propose that Geomalia is transferred to Zoothera under the name Zoothera heinrichi.

Expression and correlation of CD44v6, vascular endothelial growth factor, matrix metalloproteinase-2, and matrix metalloproteinase-9 in Krukenberg tumor

AIM： To explore the expression and correlation of CD44v6, vascular endothelial growth factor （VEGF）, matrix metalloproteinase （MMP）-2 and matrix metalloproteinase （MMP）-9 in Krukenberg and primary epithelial ovarian carcinoma. METHODS： The expressions of CD44v6, VEGF, MMP-2 and MMP-9 were detected by immunohistochemical method in 20 cases of normal ovarian tissues, 38 cases of Krukenberg tumor and 45 cases of primary epithelial ovarian carcinoma. RESULTS： The expression of CD44v6 （primary epithelial ovarian carcinoma tissue vs normal ovarian tissue： χ^2= 4.516, P= 0.034; Krukenberg tumor tissue vsnormal ovarian tissue： χ^2 = 19.537, P = 0.001） and VEGF （primary epithelial ovarian carcinoma tissue vs normal ovarian tissue： P = 0.026; Krukenberg tumor tissue vs normal ovarian tissue： χ^2 = 22.895, P = 0.001） was significantly higher in primary epithelial ovarian carcinoma tissue and Krukenberg tumor tissue than in normal ovarian tissue. The positive expression rate of MMP-2 and MMP-9 was 0% in the normal ovarian tissue. The positive expression rate of CD44v6 （ χ^2= 10.398, P= 0.001）, VEGF （ χ^2= 13.149, P = 0.001）, MMP-2 （ χ^2 = 33.668, P = 0.001） and MMP-9 （ χ^2= 38.839, P = 0.001） was remarkably higher in Krukenberg tumor than in primary epithelial ovarian carcinoma. The correlation of CD44v6, VEGF, MMP-2, and MMP-9 was observed in primary epithelial ovarian carcinoma and Krukenberg tumor. CONCLUSION： CD44v6, VEGF, MMP-2, and MMP-9 are involved in ovarian carcinoma, gastric cancer and Krukenberg tumor. Detection of CD44v6, VEGF, MMP-2 and MMP-9 may contribute to the diagnosis of ovarian carcinoma, gastric cancer, and Krukenberg tumor.

The Life of a Protein Molecule——Protein Quality Control

The research progress in molecular chaperones, unfolded protein response （UPR） and ER-associated degradation （ERAD） involved in the protein quality control was summarized in this paper, and then the existing problems and the future devel- opment prospect were also discussed. It was pointed out that the life process of protein experienced four stages including synthesizing, folding, assembling and degradation, while each stage required strict quality control. In endoplasmic reticulum （ER）, a variety of proteins had been synthesized, folded and modified to form func- tional proteins with certain conformation. When the folding was blocked in ER, the unfolded proteins would aggregate and induce the UPR, which up-regulated the level of modification enzymes folded by a series of molecular chaperones and proteins to help them accomplish folding and assembling. If these proteins were still folded incorrectly, they would enter into ERAD for being degraded.

Zinc Finger Protein-activating Transcription Factor Up-regulates Vascular Endothelial Growth Factor-A Expression in Vitro

Objective To construct the zinc finger protein-activating transcription factor (ZFP-ATF) plasmid and evaluate its efficacy in inducing vascular endothelial growth factor (VEGF) expression in EY.HY926 endothelial cells. Methods Firstly, we constructed the ZFP-ATF plasmid, then testified the quantity of VEGF protein in EY.HY926 endothelial cells after transfected with ZFP-ATP plasmid by Western blot, finally, we used the RT-PCR to testify whether the ZFP-ATF can stimulate expression of VEGF splice variants. Results The ZFP-ATF DNA sequences were located the multiclone sites of PVAX1 vector between the site of BamH Ⅰ and Xhol. Western blot result showed VEGF expression in EY.HY926 endothelial cells transfected with ZFP-ATF plasmid was significantly higher than that in cells transfected with VEGF165 (19.95±3.95 vs. 12.15±1.55 μg/μL, P<0.01). RT-PCR result showed VEGF-A mRNA expression level induced by ZFP-ATF was high than that induced by VEGF165. Conclusion ZFP-ATF can up-regulate the VEGF-A expression in comparison with VEGF165, which might have beneficial effects in angiogenesis process.

α-fetoprotein,vascular endothelial growth factor receptor-1 and early recurrence of hepatoma

AIM:To investigate whether α-fetoprotein (AFP) and vascular endothelial growth factor receptor (VEGFR)-1 correlate with early recurrence of hepatoma/hepatocel-lular carcinoma (HCC).METHODS:From 2000 to 2005,114 consecutive pa-tients with HCC underwent primary curative hepatecto-my.The mean age was 60.7 (8.7) years and 94 patients were male.The median follow-up period was 71.2 mo (range:43-100 mo).Immediately prior to commencing laparotomy,5 mL bone marrow was aspirated from thesternum and collected in citrate-coated test tubes.The initial 2 mL of bone marrow aspirate was discarded in each case.AFP mRNA and VEGFR-1 mRNA in the bone marrow and peripheral blood (BM-and PH-AFP mRNA and BM-and PH-VEGFR-1 mRNA,respectively) were measured by real-time quantitative reverse transcription polymerase chain reaction.As normal controls,VEGFR-1 mRNA in the bone marrow and peripheral blood was also measured in 11 living liver donors.These data were evaluated for any correlation with early recurrence,comparing clinical and pathological outcomes.RESULTS:The cut-off value of the BM-AFP mRNA and PH-AFP mRNA level in patients with HCC was set at 1.92 × 10-7 and zero,respectively,based on data from the controls.A total of 34 (29.8%) and six (5.4%) patients were positive for BM-AFP mRNA and PH-AFP mRNA,respectively.The BM-VEGFR-1 mRNA levels in all HCC patients were higher than those in the normal con-trols,and this was the case also for PH-VEGFR-1mRNA.The 25-percentile values for the BM-and PH-VEGFR-1 mRNA in HCC patients were used as the cut-off values for assigning the patients into two groups based on these transcript levels.The High group for BM-VEG-FR-1 mRNA contained 81 (71.1%) HCC cases and the Low group was assigned 33 (28.9%) patients.These numbers for PH-VEGFR-1mRNA were 78 (75.0%) and 26 (25.0%),respectively.HCC recurred in 80 patients;in the remnant liver in 48 cases,in the remnant liver and remote tissue in 20,and in the remote tissue alone in 12.BM-AFP mRNA-positive cases showed a signifi-cantly higher rate of early recurrence (within 1 year of surgical treatment) compared with BM-AFP mRNA-negative patients (P=0.0091).Patients were classified into four groups according to the level/status of their BM-VEGFR-1 and BM-AFP mRNA as follows:group A (n=23),BM-VEGFR-1/BM-AFP mRNA=low/negative;group B (n=57) high/negative;group C (n=10) low/positive;group D (n=24),high/positive.This classifi-cation was found to correlate with a recurrence of thisdisease within 1 year (P=0.0228).The disease-free survival curve of group A was significantly better than that of groups B,C or D (P=0.0437,P=0.0325,P=0.0225).No other classification (i.e.,PH-VEGF-R1/BM-AFP,BM-VEGF-R1/PH-AFP,and PH-VEGF-R1/PH-AFP mRNA) showed such a correlation.CONCLUSION:The evaluation of BM-AFP and BM-VEG-FR-1 mRNA in patients with HCC may be a valuable pre-dictor of disease recurrence following curative resection.

The diagnostic value of tumor abnormal protein and high sensitivity C reactive protein in screening for endometrial cancer with endometrial thickness less than 8 mm

Objective This study aimed to combine tumor abnormal protein(TAP) and high-sensitivity C-reactive protein(hs-CRP) level detection to diagnose endometrial cancer in patients with endometrial thickness less than 8 mm, and to provide a reference for clinical screening and diagnosis. Methods Clinical data from 19 cases of endometrial cancer, diagnosed on the basis of pathological findings, were collected from September 2014 to December 2015. The inclusion criteria were as follows: the patients were first diagnosed with endometrial thickness less than 8 mm and were all in menopause. Perimenopausal patients(n = 26) with uterine fibroids seen during the same period were selected as a control group. Serum TAP and hs-CRP levels of the patients in the two groups were simultaneously determined on admission. Results We found that both TAP and hs-CRP levels in the experimental group were higher than those in the control group [(182.95 ± 72.14) μm^2 vs.(133.19 ± 55.18) μm^2, P = 0.019;(7.52 ± 19.03) mg/L vs.(1.66 ± 2.31) mg/L, P = 0.136]. The sensitivity of TAP for the diagnosis of endometrial cancer was 73.68%, the specificity was 69.23%, and the Youden index was 0.4291. The diagnostic sensitivity and specificity of hs-CRP was 15.79% and 100%, respectively, and the Youden index was 0.1579. After plotting the receiver operating characteristics curves, the optimal cut-off value for TAP in diagnosing endometrial cancer was found to be 160.662 μm^2 and that for hs-CRP was 1.07 mg/L. Conclusion For patients suspected of having endometrial cancer with endometrial thickness less than 8 mm, combined detection of TAP and hs-CRP levels can be used as a screening tool and can provide new ideas regarding clinical diagnosis and treatment.

Effects of carbon dioxide pneumoperitoneum on metastasis of ovarian carcinoma cell line SKOV_3

The long suspicion of the potential harm of carbon dioxide （CO2） pneumoperitoneum exists in laparoscopic cancer surgery. For better understanding of this problem, we targeted this study at the effects of CO2 pneumoperitoneum on the invasive ability of ovarian carcinoma cell line and the possible mechanism within it. To study the effects of CO2 pneumoperitoneum on carcinoma cell, SKOV3 cells were divided into 2 groups, respectively exposed to pneumoperitoneal CO2-insuffiation and normal conditions. To study the possible mechanism, SKOV3 cells were divided into 3 groups, one was exposed to CO2 pneumoperitoneum, one to N2 and the other to normal conditions served as control. The in vitro adhesive and invasive ability of the cells was analyzed through 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl tetrazolium bromide （MTT） assay and Boyden filters metastasis model; the expressions of vascular endothelial growth factor C （VEGF-C） and matrix metalloproteinase 9 （MMP9） were determined by reverse transcription polymerase chain reaction（RT-PCR）, and Western blot. We found that the adhesive ratio of SKOV3 cells exposed to CO2 was significantly higher than that of the control group; cells exposed to CO2 invaded the matrigel with a greater number （P〈0.01）; the expression of VEGF-C exposed to both CO2 and N2 was significantly increased compared with control group （P〈0.05）; the MMP9 expression level of CO2 group was higher than that of N2 group, P〈0.05. We concluded that carbon dioxide pneumoperitoneum may improve the adhesive and invasive ability of ovarian carcinoma cell line in vitro and CO2 can also be an independent factor to stimulate the expression of MMP9.

EFFECTS OF EARLY NUTRITION INTERVENTION ON IGF1, IGFBP3,INTESTINAL DEVELOPMENT, AND CATCH-UP GROWTH OF INTRAUTERINE GROWTH RETARDATION RATS

To investigate the effects of early nutritional intervention on the serum insulin-like growth factor-1 (IGF1),insulin-like growth factor binding protein 3 (IGFBP3), intestinal development, and catch-up growth of intrauterine growth retardation (IUGR) rats by giving the IUGR new born rats different protein level diet. Methods IUGR rat model was built by starvation of pregnant female rats. Twenty-four IUGR pups and 8 normal pups were divided randomly into 4 groups: normal control group (C group); IUGR control group(S group), IUGR low-protein diet group (SL group), and IUGR high-protein diet group (SH group). Detected the serum IGF1, IGFBP3, body weight, body length, intestinal weight length, intestinal villi height (VH), crypt depth (CD), villi absorbing area (VSA), mucous thickness (MT), and disaccharidase at the 4th week. Results (1) The SH group showed the fastest catch-up growth, serum IGF1, IGFBP3, VH, and VSA were significantly higher than those of normal control group and IUGR control group. The intestinal weight and length, and the activities of lactase and saccharase of the SH group also reached the normal control group level. (2) The SL group kept on small size, the serum IGF1, IGFBP3, and most of intestinal histological indexes were all significantly lower than other groups. (3) IGF-1, IGFBP3 were positively correlated to intestinal VH, VSA, saccharase, body weight and length. Conclusions The serum IGF1 was a sensitive index to the catch-up growth. The early nutritional intervention of high-protein diet after birth is helpful for the catch-up growth of IUGR through promoting the intestinal development and the ab-sorption of nutrition

Octreotide inhibits proliferation and invasion of MHCC97-H cells in vitro and in vivo

Objective: To figure out the effect of somatostatin analogue Octreotide on proliferation and invasion of human hepatocellular carcinoma cell MHCC97-H and the underlying mechanism in vitro and in vivo. Methods: MHCC97-H cells were treated with Octreotide at the concentration of 0.2 ug/mL in vitro, proliferation related to time was evaluated. After treated with Octreotide at the concentration of 0.2 ug/mL for 48 h, MHCC97-H cells were observed by transmission electron microscope. Cell proliferation was detected by MTT assay after MHCC97-H cells were treated with Octreotide at different concentrations including 0.05, 0.1, 0.2, 0.4, 0.6 and 0.8 ug/mL for 36 h in vitro. 27 nude mice, in which MHCC97-H tumor mass was planted orthotopically, were divided into 3 groups randomly including control group (intraperitoneal injection with equal volume normal saline; n=8), low dose treated group (intraperitoneal injection with Octreotide at 50 ug/kg?d; n=9) and large dose treated group (intraperitoneal injection with Octreotide at 200 ug/kg?d; n=10). All mice were raised for 35 d and sacrificed. The information about survival time, the weight at death point and the pathology change of liver and lung was collected. The expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinases-2 (MMP-2) in mouse HCC tissues were detected by immunohistochemistry finally. Results: MTT assays showed that Octreotide inhibited the proliferation of MHCC97-H cells significantly. Apoptosis cells were found by transmission electron microscope after treatment with Octreotide at 0.2 ug/mL for 48 h in vitro. The proliferation was inhibited significantly by Octreotide in a dose-dependant manner (r=0.86, P<0.01). Compared with control group, the treated group had the heavier weight at death point and lower intrahepatic metastasis ratio (P<0.05), meanwhile, there was not significant difference in treated groups (P>0.05). The positive expression ratios of VEGF and MMP-2 in treated groups were lower than those in control group (P<0.05), while there was no apparent difference in treated groups (P>0.05). Conclusion: Octreotide could inhibit the proliferation of MHCC97-H cells in vitro via inducing apoptosis and the inhibitory function acts in a dose-dependant manner. Octreotide could improve survival of mice with MHCC97-H cells and inhibit the metastasis of MHCC97-H cells in vivo. Regulation of VEGF and MMP-2 expression by Octreotide would be involved in its inhibition in vivo.

hVEGF165 Expression in Escherichia coli Conserves Its Biological Function

The paper describes the expression of human protein VEGF165 in Escherichia coli and its purification. This growth factor isoform contains exon 7, which is essential for binding to extracellular domain of VEGF receptor 2, located on endothelial cells lining the surface of blood vessels. This binding stimulates the cascade of downstream signalling events leading to process known as angiogenesis, hVEGF165 overexpressed with His-tag in BL21 E. coli cells forms inclusion bodies （insoluble protein）, so the research found the procedure for its solubilization and purification on a Nickel based affinity chromatography. Although this eukaryotic signal protein needs posttranslational processing for its full function as a homodimer, author verified the biological activity of our hVEGF165 protein, obtained as monomer, by wound healing test.

Theoretical study on formation of thioesters via O-to-S acyl transfer

Peptide thioester preparation via intramolecular O-to-S acyl transfer is a recently developed method for protein chemical synthesis through Fmoc chemistry. Theoretical calculations have been carried out to study the mechanism for the formation of thioesters via O-to-S acyl transfer. It is found that the O-to-S acyl transfer occurs via an anionic stepwise mechanism in which the cleavage of the C-O bond is the rate-limiting step. The side reaction of hydrolysis also proceeds through an anionic stepwise process, and its rate-limiting step is the attack of the hydroxide ion on the carbonyl carbon. Increase of the chain length between the ester O atom and the S atom can increase the energy barrier of the O-to-S acyl transfer. On the other hand, substituents at the α-position of the ester can reduce the energy barrier.