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Fuchu He

Publications and source records attributed to Fuchu He.

At least 55 records · Page 3Linked to original sources
PubMed2004

Variants in TNFRSF5 locus and association analysis with Hepatitis B virus (HBV) infection.

Human TNFRSF5, a key signaling molecule expressed by antigen-presenting cells of the immune system, might have associations with autoimmune diseases and various infectious diseases. In the present study, we screened single-nucleotide polymorphisms (SNPs) in TNFRSF5 and examined whether they are risk factors for persistent HBV infection or disease severity. We resequenced all 9 exons, the promoter and splicing regions of all introns for 186 Chinese individuals, and identified 11 SNPs. Haplotypes and their frequencies were estimated. The linkage disequilibrium (LD) pattern was also evaluated. Neutrality tests indicated that the variation pattern at TNFRSF5 locus departs from neutrality and may be maintained by positive selection or demography factors such as population growth. Three SNPs (g.53031T>C, g.54068T>C and g.64493A>G) were determined as haplotype-tag SNPs (htSNPs). Furthermore, computer analyses indicated that sequences surrounding g.53031T>C and g.53824T>C were potential binding sites for transcription factors Sp1 and H4TF-2, respectively. We then genotyped these four SNPs for 603 persistent HBV infection patients and 384 spontaneously recovered subjects by PCR direct sequencing. No statistically significant associations were observed between any of the SNPs or haplotypes and persistent HBV infection or disease severity. The information from this study of the TNFRSF5 would be useful for genetic studies of other common diseases.

Adult↗
PubMed2004

Proteomic analysis on structural proteins of Severe Acute Respiratory Syndrome coronavirus.

Recently, a new coronavirus was isolated from the lung tissue of autopsy sample and nasal/throat swabs of the patients with Severe Acute Respiratory Syndrome (SARS) and the causative association with SARS was determined. To reveal further the characteristics of the virus and to provide insight about the molecular mechanism of SARS etiology, a proteomic strategy was utilized to identify the structural proteins of SARS coronavirus (SARS-CoV) isolated from Vero E6 cells infected with the BJ-01 strain of the virus. At first, Western blotting with the convalescent sera from SARS patients demonstrated that there were various structural proteins of SARS-CoV in the cultured supernatant of virus infected-Vero E6 cells and that nucleocaspid (N) protein had a prominent immunogenicity to the convalescent sera from the patients with SARS, while the immune response of spike (S) protein probably binding with membrane (M) glycoprotein was much weaker. Then, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to separate the complex protein constituents, and the strategy of continuous slicing from loading well to the bottom of the gels was utilized to search thoroughly the structural proteins of the virus. The proteins in sliced slots were trypsinized in-gel and identified by mass spectrometry. Three structural proteins named S, N and M proteins of SARS-CoV were uncovered with the sequence coverage of 38.9, 93.1 and 28.1% respectively. Glycosylation modification in S protein was also analyzed and four glycosylation sites were discovered by comparing the mass spectra before and after deglycosylation of the peptides with PNGase F digestion. Matrix-assisted laser desorption/ionization-mass spectrometry determination showed that relative molecular weight of intact N protein is 45 929 Da, which is very close to its theoretically calculated molecular weight 45 935 Da based on the amino acid sequence deduced from the genome with the first amino acid methionine at the N-terminus depleted and second, serine, acetylated, indicating that phosphorylation does not happen at all in the predicted phosphorylation sites within infected cells nor in virus particles. Intriguingly, a series of shorter isoforms of N protein was observed by SDS-PAGE and identified by mass spectrometry characterization. For further confirmation of this phenomenon and its related mechanism, recombinant N protein of SARS-CoV was cleaved in vitro by caspase-3 and -6 respectively. The results demonstrated that these shorter isoforms could be the products from cleavage of caspase-3 rather than that of caspase-6. Further, the relationship between the caspase cleavage and the viral infection to the host cell is discussed.

Amino Acid Sequence↗
PubMed2004

Applications of proteomics in hepatic diseases research.

Proteomics has become an important part in the leading research area and been widely used in the disease-associated study. In hepatic research field, proteomics could be applied in study of hepatic diseases including liver cancer, cirrhosis and hepatotoxicities, etc. Significant proteins could be identified as biomarkers, drug targets and clues for pathogenesis illumination.

Animals↗
PubMed2003

Substantial reduction in risk of lung adenocarcinoma associated with genetic polymorphism in CYP2A13, the most active cytochrome P450 for the metabolic activation of tobacco-specific carcinogen NNK.

Cytochrome P450 2A13 (CYP2A13), an enzyme expressed predominantly in the human respiratory tract, exhibits high efficiency in the metabolic activation of tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). A C-->T transition in the CYP2A13 gene causes Arg257Cys amino acid substitution and, thus, results in a significantly reduced activity toward NNK and other substrates. In this case-control study, we genotyped 724 patients with lung cancer and 791 controls for this polymorphism to examine the hypothesis that the variant CYP2A13 may have impact on risk of lung cancer in relation to tobacco smoking. A gene deletion polymorphism (CYP2A6*4) in CYP2A6, another enzyme involved in the metabolic activation of tobacco nitrosamines, was also analyzed as a comparison. We found that, compared with the CC genotype, the variant CYP2A13 genotype (CT + TT) was associated with substantially reduced risk for lung adenocarcinoma [odds ratio (OR), 0.41; 95% confidence interval (CI), 0.23-0.71], but not squamous cell carcinoma (OR, 0.86; 95% CI, 0.57-1.29) or other types of lung cancer (OR, 0.58; 95% CI, 0.32-1.09). Stratification analysis shows that the reduced risk of lung adenocarcinoma related to the variant CYP2A13 genotype was limited to smokers, especially light smokers (OR, 0.23; 95% CI, 0.08-0.68) but not nonsmokers or heavy smokers. No association was observed between CYP2A6 genotype and risk of lung cancer. Our results demonstrate for the first time that the variant CYP2A13 allele is associated with reduced risk of lung adenocarcinoma, suggesting the role of NNK-CYP2A13 interaction as a causative factor for the cancer.

Adenocarcinoma↗
PubMed2003

LDA--a java-based linkage disequilibrium analyzer.

UNLABELLED: We describe an integrated java-based program that provides elaborate graphic and plain-text output of pairwise linkage disequilibrium (LD) analysis of single nucleotide polymorphisms genotypic data. It is most suitable for molecular geneticists, who are focusing on LD measures estimation, statistical significance test and extent prediction. AVAILABILITY: The software is available at: http://www.chgb.org.cn/lda/lda.htm. SUPPLEMENTARY INFORMATION: Detailed tutorials, LDA help system and examples are distributed within LDA software. For Macintosh OS X user, the Jre version 1.4 can be downloaded from http://connect.apple.com.

Algorithms↗
PubMed2003

The potentiation role of hepatopoietin on activator protein-1 is dependent on its sulfhydryl oxidase activity.

Hepatopoietin (HPO) is a novel hepatotrophic growth factor that stimulates hepatocyte proliferation by two pathways. In the first, intracellular HPO specifically modulates the activator protein-1 (AP-1) pathway through JAB1 (Jun activation domain-binding protein 1), whereas in the second, extracellular HPO triggers the mitogen-activated protein kinase pathway by binding its specific receptor on the cell surface. In this report we demonstrate that HPO is a flavin-linked sulfhydryl oxidase, and the invariant CXXC (Cys-Xaa-Xaa-Cys) motif in HPO is essential for the enzyme activity of HPO but not for its dimerization nor for its binding ability with JAB1. Two intramolecular disulfides were identified in HPO by mass spectrometry, one of which is formed by the redox CXXC cysteine residues. HPO site-directed mutants (Cys/Ser) at active sites, which lost sulfhydryl oxidase activity, could not increase c-Jun phosphorylation and failed to potentiate JAB1-mediated AP-1 activation. However, the mutants still have mitogenic stimulation and mitogen-activated protein kinase activation effects on HepG2 cells. Thus, it can be concluded that the potentiation role of HPO on AP-1 is dependent on its sulfhydryl oxidase activity.

Amino Acid Sequence↗
PubMed2003

Haplotype structure and evidence for positive selection at the human IL13 locus.

Interleukin-13 (IL13) is believed to play an important role in the pathogenesis of atopy and allergic asthma. To better understand genetic variation at the IL13 locus, we resequenced a 5.1-kb genomic region spanning the entire locus and identified 26 single-nucleotide polymorphisms (SNPs) in 74 individuals from three major populations-Chinese, Caucasian, and African. Our survey suggests exceptionally high and significant geographic structure at the IL13 locus between African and outside Africa populations. This unusual pattern suggests that positive selection that acts in some local populations may have played a role on the IL13 locus. In support of this suggestion, we found a significant excess of high frequency-derived SNPs in the Chinese population and Caucasian population, respectively, as expected after a recent episode of positive selection. Further, the unusual haplotype structure indicates that different scenarios of the action of positive selection on the IL13 locus in different populations may exist. In the Caucasian population, the skewed haplotype distribution dominated by one common haplotype supports the hypothesis of simple directional selection. Whereas, in the Chinese population, the two-round hitchhiking hypothesis may explain the skewed haplotype structure with three dominant ones. These findings may provide insight into the likely relative roles of selection and population history in establishing present-day variation at the IL13 locus, and, motivate further studies of this locus as an important candidate in common diseases association studies.

Asian People↗
PubMed2003

An initiator and its flanking elements function as a core promoter driving transcription of the Hepatopoietin gene.

Hepatopoietin (HPO)/ALR (augmenter of liver regeneration), as a versatile hepatotrophic growth factor and a cellular thiol oxidase, is involved in a wide variety of basic processes of various tissues, especially in liver and testis. Here, we studied the regulation of HPO gene expression. By sequential deletion of the HPO 5'-flanking region, the minimal promoter of the HPO gene was shown to span positions -22 to +42 relative to the transcriptional start point. Further transfection assay and mutation analysis showed that the core promoter contains a functional initiator. Interestingly, three tandem repeats of a CTGGAGGC element, surrounding the transcription start site and bound by specific nuclear factors, were found to be pivotal for the promoter activity. This initiator flanking element functions in an initiator-dependent fashion and is present in many initiator-containing genes. Taken together, our findings revealed that the initiator-like element and its flanking repeat sequence comprise a core promoter and drive the transcriptional initiation of the HPO gene in a combinatorial manner. The HPO gene promoter might represent a novel architecture for core promoters.

Base Sequence↗
PubMed2003

Identification of metastasis-associated proteins by proteomic analysis and functional exploration of interleukin-18 in metastasis.

Very little is currently known about mechanisms underlying cancer metastasis. In the present study, metastasis-associated proteomes were separated and identified by comparative proteomic analysis, and the metastasis-related function of candidate protein interleukin-18 (IL-18) was further elucidated. First, a pair of highly and poorly metastatic sublines (termed PLA801D and PLA801C, respectively), originating from the same parental PLA801 cell line, was identified by spontaneous tumorigenicity and metastasis in vivo and characterized by metastatic phenotypes analysis in vitro. Subsequently, a proteomic approach was used to compare the protein expression profiles between PLA801C and PLA801D sublines. Eleven proteins were identified and further verified by one-dimensional Western blotting, Northern blot and/or semiquantitative reverse transciptase polymerase chain reaction analysis. Compared with those in poorly metastatic PLA801C subline, cytokeratin 18, tissue transglutaminase, Rho GDP-dissociation inhibitor 1, tropomyosin, fibroblast type, IL-18 and annexin I were significantly up-regulated, while protein disulfide isomerase, heat shock protein 60, peroxiredoxin 1, chlorine intracellular channel protein 1 (CLI1) and creatine kinase, B chain were significantly down-regulated in the highly metastatic PLA801D subline. Intriguingly, all the identified candidate proteins except for CLI1 have been shown to be somehow associated with distinct aspects of tumor metastasis such as cell growth, motility, invasion, adhesion, apoptosis and tumor immunity, etc. Considering that IL-18 was present in highly metastatic PLA801D but absent in poorly metastatic PLA801C, the association of IL-18 with metastasis was further elucidated by introducing IL-18 sense/IL-18 antisense into PLA801C/PLA801D sublines simultaneously. The results demonstrated that ectopically expressed IL-18 promoted cell motility in vitro and down-regulated E-cadherin expression of PLA801C transfectants, while IL-18 antisense remarkably decreased cell invasion potency in vitro and notably increased E-cadherin expression of PLA801D transfectants, indicating that IL-18 might play a role in metastasis by inhibiting E-cadherin expression.

Animals↗
PubMed2003

Phylogeny of a growth hormone-like cytokine superfamily based upon 3D structure.

Cytokines are of central importance in the regulation of hematopoiesis, immunity, inflammation, tissue remodeling, and embryonic development. Cytokine research is expected to provide the key to pharmacological manipulation of the immune response and commands the attention of a massive and highly focused biotechnology industry. Based upon the hypothetical secondary and tertiary structures, a superfamily of growth hormone (GH)-like cytokine was identified previously. Here, we report the phylogeny of this superfamily based upon 3D structural data from the Protein Data Bank. First, a retrieving program is designed to abstract their secondary structures and associated atomic coordinates. Helices, digitized as vectors in the Cartesian coordinate system, are collected from the retrieved atomic coordinates at the alpha carbons of the protein backbone. Then the scalar value and vector angle against the reference vector, usually the first vector, are calculated. Furthermore, cluster analysis among various cytokines is performed on their helical scales and helical angles. As a result, GH is close to the cluster formed by ciliary neurotrophic factor and granulocyte colony-stimulating factor (CSF); leptin and erythropoietin are in descending order close to the cluster formed by interleukin (IL)-6 and IL-10; the former seven members in the two subgroups above join together and form one group with leukemia inhibitory factor; granulocyte-macrophage CSF, IL-2, IL-4, and IL-5 are in descending order close to the cluster formed by IL-3 and macrophage CSF; and the latter six members form another group. Finally, it is demonstrated that the phylogeny of GH-like cytokines above is consistent with the evolutionary relationship of their gene organization, gene localization, receptor module composition, and receptor module compatibility.

Animals↗
PubMed2003

Advances in the study of SR protein family.

The name of SR proteins is derived from their typical RS domain that is rich in serine (Ser, S) and arginine (Arg, R). They are conserved in evolution. Up to now, 10 members of the SR protein family have been identified in humans. SR proteins contain one or two RNA binding motifs aside from the RS domain, and also possess special biochemical and immunological features. As to the functions of SR proteins, they facilitate the recruitment of the components of splicesome via protein-protein interaction to prompt the assembly of early splicesome; while in alternative splicing, tissue-specifically expressed SR protein along with the relative ratio of SR protein and heterogeneous nuclear ribonucleoprotein (hnRNP) is composed of two main regulative mechanisms to alternative splicing. Almost all of the biochemical functions are regulated by reversible phosphorylation.

Alternative Splicing↗
PubMed2003

Histamine N-methyltransferase gene polymorphisms in Chinese and their relationship with enzyme activity in erythrocytes.

The aim of this study was to identify polymorphisms in the histamine N-methyltransferase (HNMT) gene in Chinese and to assess their relationship with HNMT activity. One hundred and ninety-two unrelated subjects were recruited. HNMT polymorphisms were screened by direct sequencing with purified polymerase chain reaction products comprising all six exons, plus splice junctions, as well as approximately 2 kb of the 5'-flanking region (5'-FR). Erythrocyte HNMT activity was previously measured by radiochemical microassay. A total of 11 single nucleotide polymorphisms (SNPs) were identified, among which six SNPs had variant allele frequencies greater than 5%. Of the six common SNPs, three (-1637T>C, -463T>C and -411C>T) were located in 5'-FR, one (314C>T) in coding exons, and two (939A>G and 1097A>T) in the 3'-untranslated region (3'-UTR). Most of these common SNPs were in linkage disequilibrium. Genotype-phenotype correlation analyses were performed for those common SNPs in 5'-FR and 3'-UTR. In males, no significant association was found between HNMT activity and these non-coding SNPs. However, in females, the -1637T>C or -463T>C tended to be associated with decreased HNMT activity, whereas the 939A>G or 1097A>T appeared to be correlated with increased enzymatic activity. HNMT polymorphisms differ considerably between Chinese and American. The common SNPs in 5'-FR (-1637T>C and -463T>C) and 3'-UTR (939A>G and 1097A>T) might conditionally regulate the activity of HNMT, or might be genetically linked to unknown mutation(s) underlying the HNMT phenotypic variance.

3' Untranslated Regions↗
PubMed2002

Identification, characterization, and functional study of the two novel human members of the semaphorin gene family.

We cloned two novel human transmembrane semaphorins, (HSA)SEMA6C and (HSA)SEMA6D, that belong to the class VI subgroup of the semaphorin family. The genes for SEMA6C and SEMA6D are mapped on chromosome 1q12-21.1 and 15q21.1, respectively. Among the adult tissues, SEMA6C is expressed only in skeletal muscle, whereas SEMA6D is expressed abundantly in kidney, brain, and placenta and moderately in the heart and skeletal muscles. During murine development, neither SEMA6C nor SEMA6D was expressed in embryonic day 10.5 (E10.5) embryos, but both were highly expressed in the areas of the lateral ventricle, the striatum, the wall of the midbrain, the pons/midbrain junction, and the choroid plexus of E13 embryos. Were neurons, neither axons nor astrocytes, highly expressed both semaphorins. Three isoforms of SEMA6C and five isoforms of SEMA6D derived from alternative splicing were identified, and their expression was regulated in a tissue- and development-dependent manner. Deletion analysis indicated that a sema domain and a PSI domain are integrally necessary for correct post-translation modification and subcellular localization. The extracellular domain of SEMA6C inhibited axonal extension of nerve growth factor-differentiated PC12 cells and induced the growth cone collapse of chicken dorsal root ganglion, rat hippocampal neurons, and rat cortical neurons in a dose-responsive manner. SEMA6D acted like SEMA6C except it had no significant effect on the growth cones of rat cortical neurons.

Alternative Splicing↗
PubMed2002

[Effect of recombinant human augmenter of liver regeneration on gene expression of tissue inhibitor of metalloproteinase-1 in rat with experimental liver fibrosis].

OBJECTIVE: To investigate the influence of recombinant human augmenter of liver regeneration (hALR) on gene expression of tissue inhibitor of metalloproteinase-1 (TIMP1) in rat with experimental liver fibrosis. METHODS: Carbon tetrachloride was injected into the peritoneal cavities of 150 rats twice a week for 8 weeks. Albumin sensitization and caudal vein attack were conducted to another 136 rats for the duration of 3.5 months, so as to establish two kinds of animal model of experimental liver fibrosis. Recombinant hALR at different doses was given during the process of model making. Specimens of liver were taken at different time-points, then the total RNA of liver tissues was isolated and TIMP1 gene expression levels were measured by reverse transcription polymerase chain reaction. RESULTS: In both rat models, TIMP(1) gene expression levels increased gradually during the process of model making. The TIMP(1) gene expression level in CCl4 model treated with low dose hALR was 0.86 +/- 0.13, 1.77 +/- 0.23, 2.78 +/- 0.36, and 3.76 +/- 0.50 respectively 2, 4, 6, and 8 weeks after the beginning of model making, all lower than those in the model group, however, without significant difference. The TIMP(1) gene expression level in CCl4 model treated with high dose hALR was 0.63 +/- 0.10, 1.18 +/- 0.20, 1.89 +/- 0.30, 2.63 +/- 0.33 respectively 2, 4, 6, and 8 weeks after the beginning of model making, significantly lower than those in CCl4 model treated with low dose hALR. In the albumin model group the TIMP(1) gene expression level showed no change during albumin sensitization, significantly increased during caudal vein attack, and reached the peak after medel making. The TIMP(1) gene expression level was lower in albumin model treated with low dose hALR during and after caudal vein attack than in the model group and negative control group, however, without significant difference (both P > 0.05). The TIMP(1) gene expression level in albumin model treated with high dose hALR was 2.33 +/- 0.36 and 4.02 +/- 0.53 during and after caudal vein attack respectively, significantly lower than those in CCl4 model group (0.99 +/- 0.14, 2.03 +/- 0.30, 2.99 +/- 0.43, and 4.13 +/- 0.44 respectively 2, 4, 6, and 8 weeks after beginning of model making respectively) and those in albumin model without hALR treatment and that with low dose hALR (4.13 +/- 0.60 and 5.99 +/- 0.83, and 3.70 +/- 0.82 and 5.63 +/- 0.89 during and after caudal vein attack respectively), and negative control group. CONCLUSION: High dose recombinant human augmenter of liver regeneration is effective in inhibiting gene expression of TIMP(1) in experimental liver fibrosis.

Animals↗
PubMed2002

Full-length cDNA cloning of human neuroglobin and tissue expression of rat neuroglobin.

Neuroglobin is a recently discovered respiratory, porphyrin-containing protein that is expressed in the brain of mouse and human. However, the full-length cDNA sequence and genomic organization of human neuroglobin have not been reported. In this paper, the full-length cDNA sequence of human neuroglobin was cloned following bioinformatic analysis and the rapid amplification of cDNA ends (RACE) technique. It was shown that the full-length cDNA sequence (GenBank Accession No. AF422796) of human neuroglobin is 1909 bp in size, and the genomic sequence is 8041 bp in size (GenBank Accession No. AF422797). To further study the characterization of this gene, the coding region of rat neuroglobin (GenBank Accession No. AF333245) was cloned by using degeneracy PCR. The result showed high conservation among human, rat, and mouse neuroglobin. Furthermore, it was demonstrated that NGB was extensively expressed in rat brain by using in situ hybridization and the immunohistochemical technique. Transcription of NGB mRNA was shown to be widely distributed throughout the adult rat brain, including cerebral cortex, hippocampus, thalamus, hypothalamus, olfactory bulb, and cerebellum. NGB protein immunoreactive cells were also widely distributed throughout normal adult rat brain, including cerebral cortex, hippocampus, thalamus, hypothalamus, pons, and cerebellum. It could be seen that the NGB-immunopositive signals were in the cytoplasma and processes of the neuron. These data strongly support the notion that neuroglobin is a highly conserved gene in evolution and is very important in the nervous system, possibly related to the oxygen supply of the neuron.

Aging↗
PubMed2002

Characterization and expression of three novel differentiation-related genes belong to the human NDRG gene family.

NDRG1 (N-Myc downstream regulated) is upregulated during cell differentiation, repressed by N-myc and c-myc in embryonic cells, and suppressed in several tumor cells. A nonsense mutation in the NDRG1 gene has been reported to be causative for hereditary motor and sensory neuropathy-Lom (HMSNL), indicating that NDRG1 functions in the peripheral nervous system necessary for axonal survival. Here, we cloned three human cDNAs encoding NDRG2 (371aa), NDRG3 (375aa) and NDRG4 (339aa), which are homologous to NDRG1. These three genes, together with NDRG1, constitute the NDRG gene family. The phylogenetic analysis of the family demonstrated that human NDRG1 and NDRG3 belong to a subfamily, and NDRG2 and NDRG4 to another. At amino acid (aa) level, the four members share 53-65% identity. Each of the four proteins contains an alpha/beta hydrolase fold as in human lysosomal acid lipase. Expression of the fusion proteins NDRG2/GFP, NDRG3/GFP and NDRG4/GFP in COS-7 cells showed that all of them are cytosolic proteins. Based on UniGene cluster analysis, the genes NDRG2, NDRG3 and NDRG4 are located at chromosome 14q11.1-11.2, 20q12-11.23 and 16q21-22.1, respectively. Northern and dot blot analysis shows that all of the three genes are highly expressed in adult brain and almost not detected in the eight human cancer lines. In addition, in contrast to the relatively ubiquitous expression of NDRG1, NDRG2 is highly expressed in adult skeletal muscle and brain, NDRG3 highly expressed in brain and testis, and NDRG4 specifically expressed in brain and heart, suggesting that they might display different specific functions in distinct tissues.

Amino Acid Sequence↗
PubMed2002

Identification of hepatopoietin dimerization, its interacting regions and alternative splicing of its transcription.

Hepatopoietin (HPO) is a novel human hepatotrophic growth factor. Recently, we demonstrated that the extracellular ligand form of HPO can stimulate proliferation of hepatic cells via its specific receptor, which is on the surface of these cells. Also, the intracellular form of HPO potentiates the transcriptional factor AP-1. Intriguingly, a variety of HPO complexes with different molecular masses were detected in hepatocytes. In this study, we screened a human fetal liver cDNA library using the yeast two hybrid system with HPO as bait, hoping to find an HPO-binding protein. Surprisingly, HPO, itself, and a previously unidentified alternatively spliced form of HPO (named HPO23) were identified as interacting with HPO, indicating that HPO may exist as a homodimer or heterodimer. These results were further confirmed in vitro and in vivo. First, mass spectrometry analysis demonstrated that recombinant human HPO exist as a homodimer and that disulfide bonds were involved in the formation of rhHPO dimer. Secondly, a pull-down experiment confirmed that GST-HPO and HA-HPO, could bind together in vitro. Using HPO and various HPO deletion mutants, we identified the extreme 30 amino acids at both N- and C-termini are essential for HPO dimerization. Finally, Western blotting analysis demonstrated that HPO exists as two isoforms at 15 kDa and 23 kDa (HPO23) in liver cells, the 15 kDa species is located in nucleus, and the 23 kDa species mainly in the cytoplasm. These results implicated that the capacity of HPO to form both homodimers and heterodimers with the alternatively spliced forms might contribute to the existence of various HPO complexes in hepatic cells.

Alternative Splicing↗