Research advances of LINE-1 in tumor / 国际肿瘤学杂志

The abnormality of long interspersed nuclear element-1 (LINE-1) is closely related to the occurrence and development of tumor.Overexpression of LINE-1 can promote cell proliferation and affect the prognosis and metastasis of tumor.The retrotransposition and methylation status of LINE-1 have potential application value in clinical diagnosis,prognosis,disease monitoring and treatment.

Foldback Intercoil DNA and the Mechanism of DNA Transposition

Foldback intercoil (FBI) DNA is formed by the folding back at one point of a non-helical parallel track of double-stranded DNA at as sharp as 180degrees and the intertwining of two double helixes within each other's major groove to form an intercoil with a diameter of 2.2 nm. FBI DNA has been suggested to mediate intra-molecular homologous recombination of a deletion and inversion. Inter-molecular homologous recombination, known as site-specific insertion, on the other hand, is mediated by the direct perpendicular approach of the FBI DNA tip, as the attP site, onto the target DNA, as the attB site. Transposition of DNA transposons involves the pairing of terminal inverted repeats and 5-7-bp tandem target duplication. FBI DNA configuration effectively explains simple as well as replicative transposition, along with the involvement of an enhancer element. The majority of diverse retrotransposable elements that employ a target site duplication mechanism is also suggested to follow the FBI DNA-mediated perpendicular insertion of the paired intercoil ends by non-homologous end-joining, together with gap filling. A genome-wide perspective of transposable elements in light of FBI DNA is discussed.

Preliminary study on K562 cells' proliferation inhibition induced by ionizing radiation / 肿瘤研究与临床

Objective To investigate the dose response relationship for K562 cells' loss of proliferation ability induced by 60Co γ ray irradiation. K562 cell morphological change and Egr-1 expression level are also investigated. Methods 3H-TdR incoporation assay, Giemsa Staining, RT-PCR were used in this study.Results It was noted that the proliferation inhibition is positively dose-dependent. K562 cells showed extensive changes in both morphology and Giemsa staining characteristics after radiation exposure. The irradiated cells acquired characteristics which the high differentiated cells had only. In the early stage after exposure to 5 Gy 60Co γ ray irradiation. A transient transcriptional upregulation of Egr-1 gene which was related to apoptosis and differentiation was observed.The transcriptional level reached its top on time point of 0.5 ～1 hours after exposure. Eight hours after exposure, the transcriptional level was below normal.Conclusions The proliferation inhibition of K562 cell is positively dose dependent. Egr-1 gene can be rapidly activated after exposure to 5 Gy 60Coγ ray. After exposure to 60Co γ ray irradiation, K562 cells entered into a more mature stage on differentiation of morphological

Choice of viral vector for gene therapy on hematological malignancies / 白血病·淋巴瘤

Gene therapy,a target therapy with biological markers,can be used as an alternative choice for refractory and relapsed hematologic malignancies. Reasonable choice of viral vectors is the key to treatment.This article will be reviewed on five aspects,which are the characteristics of the carrier,gene insertion mutation,the immune barrier,improvement the targeting of the vector and maintenance and expression of the transgene.

Distribution of a Ty3/gypsy-like retroelement on the A and B-chromosomes of Cestrum strigilatum Ruiz & Pav. and Cestrum intermedium Sendtn. (Solanaceae)

Retroelements are a diversified fraction of eukaryotic genomes, with the Ty1/copia and Ty3/gypsy groups being very common in a large number of plant genomes. We isolated an internal segment of the Ty3/gypsy retroelement of Cestrum strigilatum (Solanaceae) using PCR amplification with degenerate primers for a conserved region of reverse transcriptase. The isolated segment (pCs12) was sequenced and showed similarity with Ty3/gypsy retroelements of monocotyledons and dicotyledons. This segment was used as probe in chromosomes of C. strigilatum and Cestrum intermedium. Diffuse hybridization signals were observed along the chromosomes and more accentuated terminal signals in some chromosome pairs, always associated with nucleolus organizer regions (NORs). The physical relationship between the hybridization sites of pCs12 and pTa71 ribosomal probes was assessed after sequential fluorescence in situ hybridization (FISH). Hybridization signals were also detected in the B chromosomes of these species, indicating an entail among the chromosomes of A complement and B-chromosomes.

PrimateDB: Development of Primate Genome DB and Web Service

The comparative analysis of the human and primate genomes including the chimpanzee can reveal unique types of information impossible to obtain from comparing the human genome with the genomes of other vertebrates. PrimateDB is an open depository server that provides primate genome information for the comparative genome research. The database also provides an easy access to variable information within/between the primate genomes and supports analyzed information, such as annotation and retroelements and phylogeny. The comparative analyses of more primate genomes are also being included as the long-term objective.

Periodic Explosive Expansion of Human Retroelements Associated with the Evolution of the Hominoid Primate

Five retroelement families, L1 and L2 (long interspersed nuclear element, LINE), Alu and MIR (short interspersed nuclear element, SINE), and LTR (long terminal repeat), comprise almost half of the human genome. This genome-wide analysis on the time-scaled expansion of retroelements sheds light on the chronologically synchronous amplification peaks of each retroelement family in variable heights across human chromosomes. Especially, L1s and LTRs in the highest density on sex chromosomes Xq and Y, respectively, disclose peak activities that are obscured in autosomes. The periods of young L1, Alu, LTR, and old L1 peak activities calibrated based on sequence divergence coincide with the divergence of the three major hominoid divergence as well as early eutherian radiation while the amplification peaks of old MIR and L2 account for the marsupial-placental split. Overall, the peaks of autonomous LINE (young and old L1s and L2s) peaks and non-autonomous SINE (Alus and MIRs) have alternated repeatedly for 150 million years. In addition, a single burst of LTR parallels the Cretaceous-Tertiary (K-T) boundary, an exceptional global event. These findings suggest that the periodic explosive expansions of LINEs and SINEs and an exceptional burst of LTR comprise the genome dynamics underlying the macroevolution of the hominoid primate lineage.