Low-molecular-weight protein (LMP)2/LMP7 abnormality underlies the downregulation of human leukocyte antigen class I antigen in a hepatocellular carcinoma cell line.

BACKGROUND: Tumor cells may alter the expression of numerous components involved in antigen-processing machinery to decrease human leukocyte antigen (HLA) class I expression, allowing the tumor cells to escape immune surveillance. The purpose of the present study was to investigate the involvement of these components in the downregulation of HLA class I expression in human hepatocellular carcinoma cell line BEL7,404. METHODS: Expression of HLA-I and antigen presentation-related genes were analyzed by flow cytometry and polymerase chain reaction. The HLA class I-deficient BEL7,404 cell was transfected with the low-molecular-weight protein (LMP) 2 and LMP7 gene and were analyzed by flow cytometry for restoration of surface HLA class I expression. RESULTS: The BEL7,404 cells downregulated the expression of HLA class I antigen and lacked expression of LMP2 and LMP7. Interferon (IFN)-gamma treatment increased the expression of LMP2 but not LMP7. The LMP2-transfected BEL7,404 cells or LMP2 and LMP7-cotransfected cells restored surface HLA class I expression while LMP7-transfected cells did not. However, in IFN-gamma-treated BEL7,404 cells, transfection with the LMP7 gene induced more HLA class I expression than mock transfection. CONCLUSIONS: The LMP2 gene was required for the expression of HLA class I molecules in BEL7,404. The LMP7 was not the major reason for loss of HLA class I in BEL7,404 cells, although the supply of exogenous LMP7 could increase surface expression of HLA class I antigen.

[Characterization of antigenic epitopes of ORF2 encoded proteins of hepatitis E virus genotype 4 identified in China].

To characterize antigenic epitopes of hepatitis E virus (HEV) genotype 4 that was first identified in China a few years ago, a recombinant protein, p166Chn, encoded by HEV genotype 4 ORF2 was used to prepare anti-p166Chn McAbs. Simultaneously, twenty N- or C-terminal truncated p166Chn proteins were generated. Immunoreactivity between the McAbs and the truncated proteins as well as seven p166 recombinant proteins derived from different HEV genotypes and subgenotypes was detected by indirect ELISA, Western blot and competition inhibition ELISA. Two reactive profiles were observed with different McAbs and different truncated proteins. The McAbs, represented by 1G10, reacted with those N-terminal truncated proteins beginning at upstream of aa477 and those C-terminal truncated proteins ending at down-stream of aa613, suggesting that the epitope recognized by 1G10 relied on the region of aa477aa613 and was conformation-dependent. While McAb 2F11 was reactive to those truncated p166Chn proteins beginning at upstream of aa474 or ending at downstream of aa617, indicating that the epitope recognized by 2F11 was also conformation-dependent and relied on a longer peptide of aa474aa617. However, the two groups of McAbs didn't inhibit each other when tested by a competition inhibition ELISA, which confirmed the different spatial positions of the two epitopes. Furthermore, when p166 proteins derived from different HEV genotypes and subtypes were applied, all of the McAbs prepared against pChn166 of genotype 4 identified in China could react with the proteins of genotype 1, 2 and 3 distributed worldwide. The data suggested that the two identified epitopes were HEV genotype-common and played significant effects on cross immunoreactivity between different HEV genotypes.

[Nuclear gene involves in phenotype of non-syndromic deafness associated with mitochondrial 12S rRNA mutation].

The human mitochondrial 12S rRNA gene mutation at position 1555 associated with non-syndromic deafness and aminoglycoside-induced deafness. Family of Huaiyin in Jiangsu is one of the biggest non-syndromic deafness family in the world. In this family, deafness is maternally inherited. After establishing immortal lymphoblastoid cell lines of the family by EB virus, we analysed 17 lymphoblastoid cell lines derived, respectively, from symptomatic, asymptomatic and controll members of the family. Compared with control members, symptomatic and asymptomatic members both exhibited significant decreases in the rate of growth as well as in the rates of mitochondrial protein synthesis. But the extent of decreases is different and the severity of mitochondrial defect is related with its clinical phenotype. These results supported that the nuclear factor involves in the phenotypic manifestation of the non-syndromic deafness associated with the A1555G mutation.

[Sequence analysis of the connexin 26 genes from a deafness family with A1555G mutation in Huaiyin].

OBJECTIVE: To ascertain whether connexin 26 (Cx26) gene was a nuclear modifier gene in an extensive family with matrilineal nonsyndromic deafness associated with A1555G mutation in Huaiyin, China. METHODS: Following PCR-restriction fragment length polymorphism (PCR-RFLP) with ApaI restriction enzyme, Cx26 genes from 26 cases, with A1555G mitochondrial mutations in this family, and 62 controls (including 2 patrilineal relatives, 10 spouse controls and 50 unrelated controls), were sequenced. RESULTS: Compared with the reference sequence of Cx26 gene, totally four kinds of nucleotide changes,79G -->A, 109G-->A, 341G-->A and 235delC, were detected in a heterozygous form. However, the former three were previously reported polymorphisms, and only the 235delC was a previously described recessive mutation associated with most autosomal nonsyndromic sensorineural hearing loss in Japan and China. Further study showed that the heterozygous 235delC mutation existed in both one individual with mild hearing loss and two individuals with normal hearing. Clinical characterization showed that 235delC mutation did not seem to modify the deafness phenotype due to the A1555G mutation. Moreover, this 235delC mutation was deduced to derive from a married-in control. Finally, there were no co-segregation between the phenotypes of hearing loss and the genotypes for Cx26 genes based on the four kinds of nucleotide changes. CONCLUSIONS: The heterozygous 235delC mutation of the Cx26 gene may not modulate the severity of hearing loss associated with A1555G mutation and Cx26 gene is unlikely to be a modifier gene for hearing loss due to A1555G mitochondrial mutation in this Chinese family.

[Detection of germline mutations in the APC gene with the protein truncation test].

The protein truncation test was established for analyzing mutations in the adenomatous polyposis coli (APC) gene which plays an important role in familial adenomatous polyposis (FAP). The sites of APC mutations and the clinic features of FAP patients were examined to find the relationship between them. Genomic DNA, which was extracted from peripheral blood lymphocytes of 22 FAP patients and the normal colon tissues of 43 sporadic colorectal cancers, were examined for mutations in exon15 of the APC gene by using PCR-TNT T7 Quick Coupled Tanscription/Translation System. The subsequent sequencing was used to confirm the mutation sites. Germline mutations were found in 5 of 22 FAP patients. All of the five mutations showed base pair deletions and led to produce truncated protein. No truncating germline mutation was found in normal tissues of 43 sporadic colorectal cancers. The protein truncation test is a sensitive and accurate technique to detect truncated mutations especially in the large exons of APC gene. It can be used as an routine method for assisting the early diagnosis of the FAP patients.

Sequence analysis of the mitochondrial genome from a large family with maternally inherited nonsyndromic deafness.

OBJECTIVE: To ascertain whether other variations coexist with 1555(A--> G) mutation in the mitochondrial DNA and may aggravate the severity of hearing loss or increase the penetrance of 1555(A--> G) mutation in a large family with maternally inherited nonsyndromic deafness in Huaiyin, Jiangsu province. METHODS: PCR-restriction fragment length polymorphism (PCR-RFLP) was used to screen both the nt1555 and the nt7445 of the mitochondrial DNA from 27 maternal members in the core family; and then the mitochondrial genomes from two maternal members, and the 12S rRNA genes MTRNR1 and tRNA-Ser(UCN) gene MTTS1 from the others, were amplified by PCR-RFLP and were sequenced. RESULTS: 1555(A--> G) mutation in the mitochondrial DNA was reverified to be one of the major factors which cause maternally inherited nonsyndromic deafness and the cosegregation of 955-960(insC) and 1555(A--> G) was present in this family. Moreover, 7449 (insG), a novel homoplasmic mutation in the tRNA-Ser(UCN) gene, was found to co-exist with 1555(A--> G) mutation in two maternal members. CONCLUSION: The cosegregation of 955-960(insC) and 1555(A--> G) implies that 955-960(insC) may synergistically cause hearing loss in the presence of an 1555(A--> G) mutation, serving as an aggravating factor to enhance the sensitivity to aminoglycosides, and may sometimes increase the penetrance of 1555(A--> G) mutation.

[Establishment of Immortal Lymphoblastoid Cell Lines of Non-syndromic Deafness Family and Several Methods fro Transforming Human B Lyphocyte by EB virus.].

Reservation of rare family materials is the base for us to do further research. Family of Jiang-Su Huai-Yin is one of the biggest non-syndromic deafness families in the world. In this family,deafness is maternally inherited and all the sufferers have the mitochondrial DNA 12s RNA A1555G mutation. Four methods are used in the experiments for establishing immortal lymphoblastoid cell lines of the family with non-syndromic deafness. Results were as follows: 1 cell line was from small amout of whole blood method, 1 cell line from frozen whole blood method, 14 cell lines from frozen leukocyte method, and 36 cell lines from cyclosporin A method. In this paper, we will discuss these four methods through our experiments of establishing cell lines.

Analysis of germline mutations in the APC gene in familial adenomatous polyposis patients.

OBJECTIVE: This study was aimed at establishing an efficient mutation analysis technique system to screen the germline mutations in the adenomatous polyposis coli (APC) gene that predisposes the disease susceptibility in familial adenomatous polyposis (FAP) and to investigate the relationship between genotype and phenotype of APC gene. METHODS: Genomic DNA was extracted from the peripheral blood lymphocytes of 22 patients with clinically diagnosed FAP and was forwarded to screening for germline mutations by using denaturing high-performance liquid chromatography(DHPLC), protein truncation test (PTT) and DNA sequencing in APC gene. Analysis of genotype-phenotype was also performed on the clinical data of the FAP patients. RESULTS: Thirteen APC germline mutations were identified in 22 FAP patients. All of the mutations were nonsense or framshift mutations. Analysis of genotype-phenotype demonstrated that the FAP patients with mutations in the 5'or 3'extreme parts of the APC gene showed mild clinical symptoms. However, the FAP patients with mutations in the middle of the APC gene displayed typical or severe clinical symptoms. CONCLUSION: The technique system established in this study can efficiently and sensitively detect the mutations in APC gene. It is useful in the molecular diagnosis of pre-symptomatic FAP cases in FAP family. The clinical features of FAP patients may be related to their genotypes of APC gene.

Relationship between the downregulation of HLA class I antigen and clinicopathological significance in gastric cancer.

AIM: To discuss the expression of human leukocyte antigen (HLA) class I antigens in gastric cancer and correlate these with pathologic type and TNM stage. METHODS: The expression of HLA class I antigen was detected by immunohistochemistry in 185 specimens of gastric cancer, 20 gastric cancer specimens with lymphatic metastasis and 22 controls of normal gastric mucosa using four monoclonal antibodies. RESULTS: The expression of HLA class I antigen (B/C locus) was significantly downregulated in gastric cancer and in lymphatic metastasis than that in normal gastric mucosa (chi2=7.712, P<0.05). The expression of other HLA class I antigens was also downregulated, but the change was slight. There was no relationship between the downregulation of HLA class I antigen and that of beta2m and LMP2. The expression of HLA class I (B/C locus) was statistically correlated with pathologic stage in gastric adenocarcinoma (chi2=4.164, P<0.05). CONCLUSION: The expression of HLA class I antigen (B/C locus) was obviously downregulated in gastric cancer and in lymphatic metastasis. This abnormal expression would provide the tumor cells with a way to avoid immunological recognition.

Sequence analysis and phylogeny of deer (Cervidae) MtDNA control regions.

The complete control regions of three Muntiacinae species of Cervidae (M. reevesi, M. muntjak and M. crinifrons) were located after their complete mtDNA genomes were sequenced. In addition the control region sequences of nine species of other three Cervidae subfamilies were obtained from the Genbank. Base compositions, genetic distances and percent similarities among these regions were calculated and the homologous sequences were compared. Based on their control region sequences, the molecular phylogenetic tree was constructed by Neighbor-Joining method and rooted using the mtDNA control region sequence of O. aries. Furthermore, the phylogenetic relationship among the twelve species was discussed. The lengths of their control regions ranged from 909 bp to 1 049 bp and A + T content is 62.06%. The sequence alignment revealed considerable variation in 363 nucleotide sites (about 34%). According to the phylogenetic tree, we suggest: (1) As a whole, the phylogenetic taxon of the twelve Cervidae species based on their control region sequences is consistent with that made by the NCBI; (2) A. alces, a species of Alces (subfamily: Odocoileinae) is most antique one among the twelve Cervidae species; (3) M. reevesi is more antique than M. muntjak and M. crinifrons; (4) H. inermis, belonging to the subfamily Hydropotinae, is merged into the branch which includes C. capreolus and C. pygargus, two species of Capreolus (subfamily: Odocoileinae).

[The detection of microsatellite instability by ion-pair reversed-phase high performance liquid chromatography].

OBJECTIVE: To set up a sensitive and stable technique which has high throughout to detect the instability of microsatellite DNA. METHODS: Genomic DNA extracted from the cancer tissues and their normal tissues were subjected to microsatellite instability(MSI) analysis on five of DNA markers in 115 sporadic colorectal cancers by means of PCR and ion-pair reversed-phase high performance liquid chromatography. Genomic DNA extracted from lymphocytes in blood of 20 normal persons were analysed and used as the standard control. RESULTS: Seventeen (14.8%) MSI-H and 23(20.0%) MSI-L were found in 115 sporadic colorectal cancers. The rates of MSI in the young patients and old patients were much higher than that in the middle-age patients (P<0.05). And the rate of MSI in low differentiation group was also much higher than that in high or middle differentiation groups (P<0.05). CONCLUSION: The method the authors developed is a sensitive and accurate technique to detect MSI and has a high throughput.

[Sequence and organization of Muntiacus reevesi mitochondrial genome].

A shot-gun DNA sequence strategy was employed,in which the mitochondrial genome library of Muntiacus reevesi has been constructed to obtain the complete mitochondrial genome sequence. The Chinese Muntjac's mitochondrial genome, consisting of 16354 base pairs which encode genes for 13 proteins, 2 rRNAs, and 22 tRNAs, is similar to those mammals in both order and orientation. The sequence of rRNA gene, some of the protein-coding regions and tRNAs are highly homologous in mammals. Differences existing in the length and sequence of the D-loop regions account for the variations in mammals mitochondrial genomes.

[Cloning and sequencing of Sry gene of muntiacus].

Using the primers from SRY gene--HMG Box for PCR amplification in genomic DNA of Muntiacus reevesi cell strains, a 220bp fragment was obtained in the male but not in the female. The 220bp fragment was cloned into the pGEM-T vector using T/A clone method. The identified positive clone was sequenced. The result shows that 82.6% nucleotides(152bp/184bp) are homologous between Muntiacus Sry and human SRY gene. It suggests that SRY is highly conserved during evolution.

[12S rRNA, cytochrome b and MDR1 gene DNA sequence and phylogenetic evolution of Muntiacus (M. muntjak, M. reevesi, M. crinifros)].

In the paper, 784 bp-DNA fragmensts of 12S rRNA and cytochrome b gene on Mitochondrial DNA and 728 bp-DNA fragments of MDR1 (multidrug resistance) gene from Muntiacus (M. muntjak, M. reevesi, M. crinifrons) were amplified and sequenced, while their phylogenetic relationships and classification were analysed. The molecular phylogenetic trees were constructed based on these combined DNA sequences, the results suggested that DIST is 0.042 between M. crinifrons and M. muntjak; DIST is 0.047 between M. crinifrons and M. reevesi; DIST is 0.055 between M. muntjak and M. reevesi, counted according to the evolution speed of 2.5% per million year, the divergent time between M. crinifrons and M. muntjak is 1.68 million year; the divergent time between M. crinifrons and M. reevesi is 1.88 million year; the divergent time between M. muntjak and M. reevesi is 2.2 million year; The conclusion is that the M. crinifrons and M. reevesi were diverged from an ancestor analogied with M. muntjak, M. nuntjak is the oldest species, M. crinifrons and M. reevesi are newer ones.