Biomedical subjects

Dalong Ma

Publications and source records attributed to Dalong Ma.

At least 37 records · Page 2Linked to original sources

PubMed2004

Dysregulation of HSG triggers vascular proliferative disorders.

Vascular proliferative disorders, such as atherosclerosis and restenosis, are the most common causes of severe cardiovascular diseases, but a common molecular mechanism remains elusive. Here, we identify and characterize a novel hyperplasia suppressor gene, named HSG (later re-named rat mitofusin-2). HSG expression was markedly reduced in hyper-proliferative vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rat arteries, balloon-injured Wistar Kyoto rat arteries, or ApoE-knockout mouse atherosclerotic arteries. Overexpression of HSG overtly suppressed serum-evoked VSMC proliferation in culture, and blocked balloon injury induced neointimal VSMC proliferation and restenosis in rat carotid arteries. The HSG anti-proliferative effect was mediated by inhibition of ERK/MAPK signalling and subsequent cell-cycle arrest. Deletion of the p21(ras) signature motif, but not the mitochondrial targeting domain, abolished HSG-induced growth arrest, indicating that rHSG-induced anti-proliferation was independent of mitochondrial fusion. Thus, rHSG functions as a cell proliferation suppressor, whereas dysregulation of rHSG results in proliferative disorders.

Animals↗

PubMed2004

DLP, a novel Dim1 family protein implicated in pre-mRNA splicing and cell cycle progression.

In eukaryotes, primary transcripts undergo a splicing process that removes intronic sequences by a macromolecular enzyme known as the spliceosome. Both genetic and biochemical studies have revealed that essential components of the spliceosome include five small RNAs, U1, U2, U4, U5, and U6, and as many as 300 distinct proteins. Here we report the molecular cloning and functional analysis of a novel cDNA encoding for a protein of 149 amino acids. This protein has 38% amino acid sequence identity with and is evolutionally related to yeast Dim1 protein. Hence we named this protein DLP for Dim1-like protein. We showed that DLP is required for S/G(2) transition. We also demonstrated that DLP functions in cell nucleus and interacts with the U5-102-kDa protein subunit of the spliceosome, and blocking DLP protein activity led to an insufficient pre-mRNA splicing, suggesting that DLP is yet another protein component involved in pre-mRNA splicing. Collectively, our experiments indicated that DLP is implicated in not only cell cycle progression but also in a more specific molecular process such as pre-mRNA splicing.

Alternative Splicing↗

PubMed2004

The 5'-upstream region of human programmed cell death 5 gene contains a highly active TATA-less promoter that is up-regulated by etoposide.

The PDCD5 (programmed cell death 5), a novel apoptosis related gene, is functionally associated with cell apoptosis, exhibits a ubiquitous expression pattern and is up-regulated in some types of tumor cells undergoing apoptosis. To study the transcriptional regulation of the PDCD5 gene, we have cloned 1.1 kb of its 5'-upstream region. The DNA sequencing analysis revealed a major transcriptional start site at 72 base pairs in front of the ATG translational start codon. The upstream of the transcriptional start site lacks a canonical TATA box and CAAT box. Transient transfection and luciferase assay demonstrate that this region presents extremely strong promoter activity. The 5'-deleted sequences fused to a luciferase reporter gene demonstrated that the -555/-383 region from the transcription start site is crucial for transcriptional regulation, and the luciferase reporter gene's expression significantly increased in the early stage of cell apoptosis induced by etoposide. These results imply that the PDCD5 gene may be a target gene under the control of some important apoptosis-related transcriptional factors during the cell apoptosis.

5' Flanking Region↗

PubMed2004

An alternative form of paraptosis-like cell death, triggered by TAJ/TROY and enhanced by PDCD5 overexpression.

Accumulating reports demonstrate that apoptosis does not explain all the forms of programmed cell death (PCD), particularly in individual development and neurodegenerative disease. Recently, a novel type of PCD, designated 'paraptosis', was described. Here, we show that overexpression of TAJ/TROY, a member of the tumor necrosis factor receptor superfamily, induces non-apoptotic cell death with paraptosis-like morphology in 293T cells. Transmission electron microscopy studies reveal extensive cytoplasmic vacuolation and mitochondrial swelling in some dying cells and no condensation or fragmentation of the nuclei. Characteristically, cell death triggered by TAJ/TROY was accompanied by phosphatidylserine externalization, loss of the mitochondrial transmembrane potential and independent of caspase activation. In addition, TAJ/TROY suppressed clonogenic growth of HEK293 and HeLa cells. Interestingly, overexpression of Programmed cell death 5 (PDCD5), an apoptosis-promoting protein, enhanced TAJ/TROY-induced paraptotic cell death. Moreover, cellular endogenous PDCD5 protein was significantly upregulated in response to TAJ/TROY overexpression. These results provide novel evidence that TAJ/TROY activates a death pathway distinct from apoptosis and that PDCD5 is an important regulator in both apoptotic and non-apoptotic PCD.

Apoptosis↗

PubMed2004

Last intron of the chemokine-like factor gene contains a putative promoter for the downstream CKLF super family member 1 gene.

The genes for chemokine-like factor (CKLF) and four chemokine-like factor super family members (CKLFSF1-4) are tightly linked on chromosome 16, with only 325 bp separating CKLF and CKLFSF1. We used Northern blotting and RT-PCR to show that these two genes are expressed independently of one another. We then used a novel computational promoter prediction method based on the interaction among transcription factor binding sites (TFBSs) to identify a putative promoter region for the CKLFSF1 gene. Our method predicted a promoter region in the last intron of the upstream gene, CKLF. We PCR amplified the predicted promoter region and used a luciferase assay to show that the region was able to drive the luciferase gene. DNA decoy experiments indicated that 214 bp fragment neighboring the TATA box markedly inhibited CKLFSF1 gene expression. Sequence analysis of the region revealed a typical TATA box (TATATAA) and multiple potential transcription factor binding sites, providing further evidence for this being a functional promoter for CKLFSF1. This work provides the first evidence of a promoter from one gene located in an intron of another.

Base Sequence↗

PubMed2004

Molecular cloning and characterization of chemokine-like factor super family member 1 (CKLFSF1), a novel human gene with at least 23 alternative splicing isoforms in testis tissue.

Chemokine-like factor (CKLF) was isolated from PHA-stimulated U937 cells. It is composed of 152 amino acids and located on chromosome 16q22. Utilizing bioinformatics, based on CKLF cDNA and protein sequences, in combination with experimental validation, we identified a novel gene designated chemokine-like factor super family member 1 (CKLFSF1). CKLFSF1 maps on chromosome 16q22, and the full-length gene comprises of seven exons and six introns. Using RACE-PCR, we identified two potential alternative transcription start sites, 1A and 1B. Northern blot and RT-PCR analysis demonstrated that CKLFSF1 is predominantly expressed in human testis tissue, with only lower levels of expression in many other human tissues. RT-PCR and cDNA sequencing identified 23 alternatively spliced isoforms of CKLFSF1 in the testis tissue, which encode protein variants ranging from 36 to 169 amino acids in length. Immunohistochemistry analysis demonstrated that CKLFSF1 proteins are highly expressed in spermatocyte and in tissue fluid of human testes tissue. In light of these findings, we propose that CKLFSF1 may play an important role in spermatogenesis or testicular development.

Alternative Splicing↗

PubMed2003

Association study of the human FZD3 locus with schizophrenia.

The FZD3 protein is a transmembrane receptor for secreted Wnt glycoproteins involved in the Wnt signal transduction cascades. The alteration of Wnt signal transduction cascades has been thought to be involved in producing the cytoarchitectural defects observed in schizophrenia. Because the human FZD3 gene is mapped to chromosome 8p21, which is a potential region containing a gene for schizophrenia, it may play a role in conferring susceptibility to the disease. This study was conducted with the detection of three single nucleotide polymorphisms (SNPs) located within the FZD3 locus by using the polymerase chain reaction-based restriction fragment length polymorphism (RFLP) analysis among 246 schizophrenic family trios of Chinese Han descent.The transmission disequilibrium test (TDT) demonstrated that the three SNPs all showed a preferential transmission with a p value ranging from.0003-.000007. The global chi-squared test for haplotype transmission also showed a strong association (chi(2) = 48.84, df = 7, p <.000001).The strong association between the FZD3 locus and schizophrenia suggests that the gene itself may play a role in underlying schizophrenia, although a nearby gene responsible for predisposing to the illness cannot be ruled out.

Chromosomes, Human, Pair 8↗

PubMed2003

Association study between interleukin-1beta gene (IL-1beta) and schizophrenia.

An increasing amount of evidence suggests that the pathophysiology of schizophrenia is associated with the abnormal immune system, and cytokines may be important in schizophrenia. Among these cytokines, interleukin-1beta may play a role in the pathogenesis of the disease. In the present study, we investigated the genetic association between a TaqI polymorphism in interleukin-1beta gene (IL-1beta) and schizophrenia by restriction fragment length polymorphism (RFLP) analysis among 132 Chinese families of Han descent. The transmission disequilibrium test (TDT) did not demonstrate an allelic association with schizophrenia. Our results suggested that the TaqI polymorphism in IL-1beta gene might not confer increased susceptibility for schizophrenia.

Adolescent↗

PubMed2003

Molecular cloning and characterization of rat chemokine-like factor 1 and 2.

Chemokine-like factor 1(CKLF1) is a newly cloned cytokine with three RNA splicing isoforms. It has chemotactic activities on leukocytes and plays an important role in skeletal muscle regeneration. Here we have isolated two rat homologues of human chemokine-like factors by expressed sequence tag assembly, which are designated as rat chemokine-like factor 1 and 2 (rat CKLF1, CKLF2). The full-length cDNAs of rat CKLF1 and -2 contain 523 and 682 nucleotides and the open reading frames encoding 98 and 151 amino acids, respectively. Rat CKLF1 and -2 share about 54.1 and 59.6% homologies with human CKLF1 and -2 at the amino acid level; both rat CKLF1 and -2 contain a CX3C motif at their C-terminal regions while human CKLFs have a CC motif at the same regions. Rat CKLFs are highly expressed in testis, while human CKLFs have a broad expression spectrum across multiple tissues. Recombinant rat CKLF1 can be secreted into the cell culture supernatants and has chemotactic effects on neutrophils, macrophages and lymphocytes, which is similar to human CKLF1, while recombinant rat CKLF2 has weaker chemotactic effects on these cells. These findings show that rat CKLFs have similar bioactivity with human CKLFs, although they are different in tissue distribution and contain different characteristic motifs.

Amino Acid Sequence↗

PubMed2003

Identification of eight genes encoding chemokine-like factor superfamily members 1-8 (CKLFSF1-8) by in silico cloning and experimental validation.

TM4SF11 is only 102 kb from the chemokine gene cluster composed of SCYA22, SCYD1, and SCYA17 on chromosome 16q13. CKLF maps on chromosome 16q22. CKLFs have some characteristics associated with the CCL22/MDC, CX3CL1/fractalkine, CCL17/TARC, and TM4SF proteins. Bioinformatics based on CKLF2 cDNA and protein sequences in combination with experimental validation identified eight novel genes designated chemokine-like factor superfamily members 1-8 (CKLFSF1-8). CKLFSF1-8 form gene clusters; the sequence identities between CKLF2 and CKLFSF1-8 are from 12.5 to 39.7%. Most of the CKLFSFs have alternative RNA splicing forms. CKLFSF1 has a CC motif and higher sequence similarity with chemokines than with any of the other CKLFSFs. CKLFSF8 shares 39.3% amino acid identity with TM4SF11. CKLFSF1 links the CKLFSF family with chemokines, and CKLFSF8 links it with TM4SF. The characteristics of CKLFSF2-7 are intermediate between CKLFSF1 and CKLFSF8. This indicates that CKLFSF represents a novel gene family between the SCY and the TM4SF gene families.

Alternative Splicing↗

PubMed2003

Molecular cloning and characterization of four isoforms of mCKLF, mouse homologues of human chemokine-like factor.

Chemokine-like factor1 (CKLF1), and its three isoforms (CKLF2, 3 and 4), are recently identified human cytokines. CKLF1 is a potent chemoattractant for human leukocytes and can stimulate inflammation and the regeneration of murine skeletal muscle. CKLF2 can promote proliferation and differentiation of C2C12 muscle cells directly by inducing expression of myogenin and activating transcription factors. In the present study, we cloned CKLF murine homologues, and based on their biological and structural features, named them murine chemokine-like factor 2, 4, 5 and 6 (mCKLF2, 4, 5 and 6). mCKLF2, 4, 5 and 6 encode 152, 120, 122 and 86 amino-acid proteins, respectively. mCKLFs map to mouse chromosome 8 and have high sequence similarity to human CKLFs. Compared to human CKLFs, which have a CC motif in the C-terminal region, mCKLF2 and 4 contain a CX3C motif. Using a PCR-based approach, it appeared mCKLF2 and 5 mRNA were highly expressed in adult testis, while mCKLF4 mRNA was detected only in differentiated C2C12 cells, a pattern different from human CKLFs. Conditioned media from COS-7 cells transfected with mCKLF2 and 4 was chemotactic for mouse neutrophils, macrophages and lymphocytes. Our results show that mCKLF2, 4, 5 and 6 are four splicing variants which are homologues of human CKLFs and murine CKLFs possess distinct features compared to their human counterparts.

Alternative Splicing↗

PubMed2003

[In silico data mining of the human programmed cell death 5 (PDCD5) sequences].

OBJECTIVE: To lay foundation for the functional studies of programmed cell death 5 (PDCD5) and develop new technical pathway for bioinformatics analysis of human functional genes. METHODS: Using PDCD5 as the target molecule, intensive bioinformatics analysis of the nucleic acid and protein sequences were conducted. Data mining and comprehensive analysis by sequence against database similarity searching, ortholog structure comparison, expression profile analysis and gene "neighbor" listing were performed. RESULTS: Two human putative pseudogenes on chromosomes 12 and 5, and one mouse putative pseudogene on chromosome 1 were identified. The methanobacterium thermoautotrophicum ortholog was classified as the same fold as ubiquitin and ribosomal protein S13. The C. elegans ortholog, ubiquitin and IAP (inhibitor of apoptosis proteins) belonged to the same expression profile cluster. This cluster was related to biosynthesis and protein synthesis. PDCD5 orthologs in various genomes were adjacent to various ribosomal proteins on the chromosome. CONCLUSION: The human genome contains at least two processed pseudogenes of PDCD5. Besides the relationship with cell apoptosis, PDCD5 is predicted to have functional relationship with ubiquitin and participate in the translation regulation.

Amino Acid Sequence↗

PubMed2003

[Effects of chemokine-like factor 1 (CKLF1) on proliferation and metabolism of chondrocytes].

OBJECTIVE: To investigate the effects of chemokine-like factor 1 (CKLF1) on proliferation and metabolism of chondrocytes. METHODS: Cell culture, 3H-TdR and 3H-Proline incorporation methods were used. Chondrocytes were harvested from rabbit articular cartilage. First passage cells were seeded on 96-well plates. After synchronization, the medium was replaced by DMEM containing 5% FCS with various concentration of CKLF1 conditioned medium. The synthesis of mucopolysaccharide was detected by Saffraan O staining. The transcription of inducible nitricoxide synthase (iNOS) was detected by semi-quantitative RT-PCR. RESULTS: CKLF1 inhibited the DNA, collagen and mucopolysaccharide synthesis significantly, meanwhile, stimulated the transcription of iNOS. CONCLUSION: CKLF1 inhibits the proliferation and matrix synthesis of chondrocytes, which might be an important factor resulting in cartilage destructive lesions. CKLF1 may exert its effects on chondrocytes through iNOS pathway.

Animals↗

PubMed2003

[Characterization of programmed cell death 5 (PDCD5) gene in human cartilage and its possible significance].

OBJECTIVE: To characterize the expression of programmed cell death 5 (PDCD5) in normal and osteoarthritic human cartilage. METHODS: Articular cartilage specimens were obtained from 20 patients with osteoarthritis and 10 with femoral neck (normal cartilage) at the time of arthroplasty. Expression of PDCD5 was detected by flow cytometry, immunofluorescence, RT-PCR and immunohistochemical analysis. RESULTS: PDCD5 expression in osteoarthritis cartilage was significantly higher than in normal cartilage especially in the nucleus. PDCD5-positive chondrocytes were mainly observed in the superficial and deep zone of osteoarthritis tissue sections, and in contrast, in the superficial and middle regions of normal controls. CONCLUSION: Since apoptotic chondrocyte death occurs more frequently in osteoarthritis compared to normal cartilage and PDCD5 is an apoptosis related protein, the different expression patterns of PDCD5 in osteoarthritis and normal cartilage suggest that it might be involved in the pathogenesis of osteoarthritis.

Apoptosis↗

PubMed2003

[Alteration of the expression of cartilage matrix molecule in the cartilage by the chondrocytes from rabbit temporomandibular joint with experimental osteoarthritis and its response to interleukin-1 beta].

OBJECTIVE: To study the effect of interleukin-1 (IL-1 beta) on the metabolism of osteoarthritic and normal mature condylar chondrocytes in temporomandibular joints, and investigate the role of IL-1 beta in the pathogenesis of temporomandibular joint osteoarthritis. METHODS: The primary generation of osteoarthritic and normal condylar chondrocytes cultured in the monolayer condition was treated with 20 micrograms.L-1 recombined human interleukin-1 beta (rhIL-1 beta), and then collected to be detected with RT-PCR method for the cellular metabolism including mRNA expression of type II collagen, aggrecan, collagenase, insulin-like growth factor 1 (IGF-1), and transforming growth factor beta 1 (TGF beta 1). RESULTS: The normal mature condylar chondrocytes showed the obviously decreased mRNA expression of type II collagen and aggrecan after the intervention of exogenous IL-1 beta, but less influence could be found for the collagenase expression. The osteoarthritic condylar chondrocytes exhibited the decreased mRNA expression of type II collagen and collagenase under the effect of IL-1 beta, while the cellular mRNA expression of aggrecan didn't change obviously. The intervention of exogenous IL-1 beta didn't show an obvious influence on the cellular expression of endogenous growth factors such as IGF-1 or TGF-beta 1 for both the normal and osteoarthritic condylar chondrocytes cultured in vitro. CONCLUSION: IL-1 beta could not only disturb the expression of cartilage matrix molecules by the normal condylar chondrocytes, which lead to the lesion of condylar cartilage, but also worsen the abnormal cartilage matrix environment within the osteoarthritic condylar cartilage.

Animals↗

PubMed2002

Genome sequence of Shigella flexneri 2a: insights into pathogenicity through comparison with genomes of Escherichia coli K12 and O157.

We have sequenced the genome of Shigella flexneri serotype 2a, the most prevalent species and serotype that causes bacillary dysentery or shigellosis in man. The whole genome is composed of a 4 607 203 bp chromosome and a 221 618 bp virulence plasmid, designated pCP301. While the plasmid shows minor divergence from that sequenced in serotype 5a, striking characteristics of the chromosome have been revealed. The S.flexneri chromosome has, astonishingly, 314 IS elements, more than 7-fold over those possessed by its close relatives, the non-pathogenic K12 strain and enterohemorrhagic O157:H7 strain of Escherichia coli. There are 13 translocations and inversions compared with the E.coli sequences, all involve a segment larger than 5 kb, and most are associated with deletions or acquired DNA sequences, of which several are likely to be bacteriophage-transmitted pathogenicity islands. Furthermore, S.flexneri, resembling another human-restricted enteric pathogen, Salmonella typhi, also has hundreds of pseudogenes compared with the E.coli strains. All of these could be subjected to investigations towards novel preventative and treatment strategies against shigellosis.

Amino Acid Sequence↗

PubMed2002

Transfer of anti-TFAR19 monoclonal antibody into HeLa cells by in situ electroporation can inhibit the apoptosis.

Electroporation has been successfully used for the introduction of DNA, RNA, oligonucleotide and protein into eukaryotic and prokaryotic cells for the transformation and expression of various gene products. TFAR19 (TF-1 apoptosis-related gene 19), also designated PDCD5 (Programmed Cell Death 5), is cloned as an increased expression gene during the apoptotic process of TF-1 cell induced by cytokine withdrawal. It facilitates rather than induces apoptosis in different cell lines. To explore its molecular mechanism, we successfully transferred the anti-TFAR19 monoclonal antibody into HeLa cells by in situ electroporation and observed the apoptosis process of HeLa cells induced by etoposide with flow cytometry. We demonstrate that the introduction of anti-TFAR19 antibody can suppress the apoptosis accelerating effect of TFAR19 in its natural environment. This study shows that TFAR19 may be a critical factor for apoptosis; and transfer of monoclonal antibody into mammalian cells by in situ electroporation is a useful method to study the function of endogenous factors.

Antibodies, Blocking↗

PubMed2002

Overexpression of chemokine-like factor 2 promotes the proliferation and survival of C2C12 skeletal muscle cells.

Chemokine-like factor 1 (CKLF1) is a novel cytokine first cloned from U937 cells. It contains different splicing forms and has chemotactic effects on a wide spectrum of cells both in vitro and in vivo; it can also stimulate the regeneration of skeletal muscle cells in vivo, but the mechanism remains unclear. To probe the myogenesis function of CKLF2, which is the largest isoform of CKLFs, C2C12 murine myoblasts were stably transfected with human CKLF2 eukaryotic expression vector. Compared with control vector transfected C2C12 cells, CKLF2 overexpression causes accelerated myoblast proliferation as determined by cell counting and [(3)H]TdR incorporation assays. In addition, CKLF2 overexpression also promotes cell differentiation, which was determined by higher expression levels of myogenin, creatine kinase, myosin and the accelerated myoblast fusion. Further analysis also indicates that CKLF2 could activate the transcription activity of the bHLH/MyoD and MEF2 families. Finally, DNA synthesis and myotube formation could also be promoted by growing C2C12 cells in conditioned media from CKLF2-transfected cells. These findings strongly suggest a role for human CKLF2 in regulation of skeletal muscle myogenesis.

Animals↗