Xiaohua Ni

Molecular cloning and characterization of a novel human cAMP response element-binding (CREB) gene (CREB4)

AbstractCyclic adenosine monophosphate (cAMP) response element-binding (CREB) proteins are a family of mammalian transcription activators. We identified a novel human CREB gene (CREB4) that was 1592bp long and encoded a protein of 395 amino acid residues. The protein shared high homology to mouse CREB3 (identity 62%, similarity 72%). The expression pattern of the human CREB4 gene showed transcripts in prostate, brain, pancreas, skeletal muscle, small intestine, testis, leukocyte, and thymus, whereas in heart, lung, liver, kidney, placenta, spleen, ovary, and colon, specific bands of the transcript could not be detected. The CREB4 gene consisted of ten exons and nine introns and was mapped to chromosome 1q21.3 by means of a bioinformatics analysis.

Isolation and characterization of a human novel RAB (RAB39B) gene

Rab proteins are small-molecular-weight GTPases that control vesicular trafficking in eukaryotic cells. During the large-scale sequencing analysis of a human fetal brain cDNA library, we isolated a cDNA clone encoding a novel Rab protein, which showed 74.2% identity with previously isolated Rab39A at the amino acid level. RAB39B was expressed in a variety of human tissues and located in human chromosome Xq28. It consisted of two exons spanning 3764 bp of human genomic DNA.

Molecular cloning and characterization of a novel human Rab (Rab2B) gene

AbstractRab proteins are small-molecular-weight guanosine triphosphatases (GTPases) that control vesicular traffic in eukaryotic cells. The small GTPase Rab2 is a resident of pre-Golgi intermediates and is required for protein transport from the endoplasmic reticulum to the Golgi complex. We identified a novel human Rab (Rab2B) gene that was 2312 bp in length and encoded a protein of 216 amino acid residues. The protein shared high homology with mouse Rab2 (identity 83%, similarity 91%). The expression pattern of the human Rab2B gene showed that there is a transcript in kidney, prostate, lung, liver, thymus, colon, pancreas, and skeletal muscle, and low levels in placenta, whereas specific bands of the transcript could not be detected in heart, brain, spleen, testis, ovary, small intestine, and leukocyte. Overexpression has been observed in colon adenocarcinoma CX-1. The Rab2B gene consists of nine exons and eight introns and is mapped to chromosome 14q11.1–14q11.2 by bioinformatics analysis.

Molecular cloning and characterization of the protein 4.1O gene, a novel member of the protein 4.1 family with focal expression in ovary

AbstractProtein 4.1 is an important structural protein that is expressed in erythroid and in a variety of nonerythroid tissues. In mammalian erythrocytes, it plays a key role in regulating the physical properties of mechanical stability and deformability in membranes by stabilizing the spectrin-actin interaction. The protein 4.1 family mainly comprises 4.1R, 4.1G (general type), 4.1B (brain type), and 4.1N (neuron type). We identified a novel human 4.1 (4.1O) gene that is 2312bp in length and encodes a protein of 553 amino acid residues. The protein shared homology with mouse protein 4.1B (identity 38%, similarity 55%) with a FERM domain. The expression pattern of the human 4.1O gene in 16 tissues showed that there was a transcript only in ovary, whereas in the remaining 15 tissues, specific bands of the transcript could not be detected. In eight human fetal tissues, the specific bands of the transcript could be detected in skeletal muscle, with lower levels detected in thymus and brain. The 4.1O gene consists of 14 exons and 13 introns and was mapped to Chromosome 9q21–9q22 by bioinformatics analysis.

SPP1 promoter polymorphisms and glioma risk in a Chinese Han population

SPP1 was found to be significantly upregulated in many kinds of malignant tumors, including gliomas. Considering that gene polymorphisms have been implicated in the development of gliomas, we performed an association study between SPP1 functional promoter region polymorphisms and glioma risk in a Chinese population. We found significant evidence of an association between SPP1 promoter polymorphisms and glioma risk. For the −155_156insG variant, the −155_156GG allele was found to be significantly associated with an increased risk of glioma (P=0.020, odds ratio (OR)=1.202, 95% confidence interval (CI): 1.028–1.408). Individuals with the genotype containing the GG allele had a 1.372-fold increased risk (P=0.006, OR=1.372, 95% CI: 1.095–1.719). Further stratified analyses suggested that a significant association existed in adult glioma patients, male subjects and in cases without a family history of cancer. Alternatively, the study of single-nucleotide polymorphism −443C/T in a recessive model revealed that the genotype CC + CT significantly decreased the risk of glioma when compared with TT (P=0.023, OR=0.774, 95% CI: 0.621–0.966). After the analysis of haplotypes, the haplotype −155_156GG/−443T was represented at a significantly higher frequency in cases (P=0.029, OR=1.192, 95% CI: 1.018–1.395). Cellular assay indicated that the transcriptional activity of the SPP1 promoter containing the −155_156GG allele significantly increased in glioma cells. Thus, variants of the SPP1 promoter might influence the risk of glioma by regulating promoter activity. Further analyses are necessary to validate our observation in larger samples or in other ethnic groups.

Cloning and characterization of a novel human pantothenate kinase gene

Pantothenate kinase (PanK) is a key regulatory enzyme in the CoA biosynthetic pathway in bacteria and mammalian cells. It catalyzes the first committed step in the universal biosynthetic pathway leading to CoA. Here we report the molecular cloning and characterization of a new human PanK gene. The gene encoded a protein of 314 amino acid residues, which share high homology to mouse pantothenate kinase (mPanK) 1 beta. Northern blot analysis revealed a transcript of the gene of 2.6 kb in human liver and kidney. The human PanK gene was located to human chromosome between 10q22.3 and 10q23.2 by bioinformatics analysis.

Molecular cloning and characterization of a novel human protein phosphatase, LMW-DSP3☆

Reversible phosphorylation is recognized to be a major mechanism for the control of intracellular events in eukaryotic cells. From a human fetal brain cDNA library, we isolated a cDNA clone encoding a novel dual specificity protein phosphatase, which showed 88% identity with previously reported mouse LMW-DSP3 at the amino acid level. The deduced protein had a single dual-specificity phosphatase catalytic domain, and lacked a cdc25 homology domain. LMW-DSP3 was expressed in the heart, lung, liver, and pancreas, and the expression level in the pancreas was highest. The LMW-DSP3 gene was located in human chromosome 2q32, and consisted of five exons spanning 21kb of human genomic DNA. LMW-DSP3 fused to GST showed phosphatase activity towards p-nitrophenyl phosphate which was optimal at pH 7.0 and 40 degrees C, and the activity was enhanced by Ca(2+) and Mn(2+). The phosphatase activity of LMW-DSP3 was inhibited by orthovanate. LMW-DSP3 showed phosphatase activity toward oligopeptides containing pSer/Thr and pTyr, indicating that LMW-DSP3 is a protein phosphatase with dual substrate specificity.

Isolation and characterization of a novel human NM23-H1B gene, a different transcript of NM23-H1

AbstractThe NM23 gene is a conspicuous metastasis-suppressor gene. Eight human genes of the NM23/nucleoside diphosphate kinase family have been discovered. From our large cDNA cloning and sequencing project, we cloned a different transcript (NM23-H1B) of human NM23-H1 from 18-week-old human fetal brain. The 987-bp cDNA encodes a protein of 177 amino acid residues. Compared with NM23H1, the cDNA contained an additional NH2-terminal region (25 amino acid residues). It was mapped to chromosome 17q21.3 using bioinformatics analysis, which shows that the second exon does not exist in NM23-H1. The expression pattern of NM23-H1B showed that it was ubiquitously expressed in normal tissues (15 tissues except colon) at different levels. Our data also indicated that the expression of the transcript in tumors related to tumor differentiation: in poorly differentiated breast carcinoma GI-101, pancreatic adenocarcinoma GI-103, and undifferentiated ovarian carcinoma GI-102, there was no expression. In poorly differentiated lung carcinoma LX-1, lung carcinoma GI-117, the expression level was very low. The transcript band in well-differentiated colon adenocarcinoma CX-1 was significantly higher than that in poorly differentiated colon adenocarcinoma GI-112. A high transcription level was also found in grade IV prostatic adenocarcinoma PC3.

Molecular cloning and characterization of a novel human J-domain protein gene (HDJ3) from the fetal brain

AbstractThe J-domain is believed to be part of a chaperone involved in protein folding. From a fetal brain cDNA library, we isolated a cDNA of 3249 bp encoding a novel human J-domain protein, which was named as HDJ3. The expression pattern of HDJ3 was examined by reverse transcription/polymerase chain reaction, which suggested that the transcripts were highly expressed in human pancreas and selectively expressed in human brain, lung, liver, skeletal muscle and kidney. The results also showed that a probable splice variant of HDJ3 gene might exist. The HDJ3 gene was located on human chromosome 12q13.1-12q13.2 and consisted of seven exons spanning 8593 bp of the human genome. PSORT analysis indicated that the HDJ3 gene contained a transmembrane domain. The putative protein of the HDJ3 gene was highly homologous to rat dopamine-receptor-interacting protein, suggesting that it was a novel member of the molecular chaperone family and functionally related to dopamine signal transduction.

Cloning, mapping, and characterization of the human Rab3C gene.

Rab proteins are small molecular weight GTPases that control vesicular traffic in eukaryotic cells. A subset of Rab proteins, the Rab3 proteins are thought to play an important role in regulated exocytosis of vesicles. During the large-scale sequencing analysis of a human fetal brain cDNA library, we isolated a cDNA clone encoding a novel Rab protein, which showed 99% identity with previously isolated bovine Rab3C at the amino acid level. It contained four conserved motifs characteristic of the Rab3 family. RT-PCR analysis indicated that human Rab3C was expressed in the human brain, placenta, and lung. By mapping, we localized the Rab3C gene to human chromosome 5q13. The Rab3C gene consisted of 6 exons spanning more than 310 kb of human genomic DNA. Rab3A, Rab3B, and Rab3D have been mapped to three different chromosomes, suggesting that they are not transcripts of the same gene.