Lysosomal membrane protein Sidt2 knockout induces apoptosis of human hepatocytes in vitro independent of the autophagy-lysosomal pathway / 南方医科大学学报

OBJECTIVE@#To explore the regulatory mechanism of human hepatocyte apoptosis induced by lysosomal membrane protein Sidt2 knockout.@*METHODS@#The Sidt2 knockout (Sidt2-/-) cell model was constructed in human hepatocyte HL7702 cells using Crispr-Cas9 technology.The protein levels of Sidt2 and key autophagy proteins LC3-II/I and P62 in the cell model were detected using Western blotting, and the formation of autophagosomes was observed with MDC staining.EdU incorporation assay and flow cytometry were performed to observe the effect of Sidt2 knockout on cell proliferation and apoptosis.The effect of chloroquine at the saturating concentration on autophagic flux, proliferation and apoptosis of Sidt2 knockout cells were observed.@*RESULTS@#Sidt2-/- HL7702 cells were successfully constructed.Sidt2 knockout significantly inhibited the proliferation and increased apoptosis of the cells, causing also increased protein expressions of LC3-II/I and P62(P < 0.05) and increased number of autophagosomes.Autophagy of the cells reached a saturated state following treatment with 50 μmol/L chloroquine, and at this concentration, chloroquine significantly increased the expressions of LC3B and P62 in Sidt2-/- HL7702 cells.@*CONCLUSION@#Sidt2 gene knockout causes dysregulation of the autophagy pathway and induces apoptosis of HL7702 cells, and the latter effect is not mediated by inhibiting the autophagy-lysosomal pathway.

Recombinant lentivirus-mediated gene transfer of NT4-p53(N15)-Ant inhibits the growth of hepatocellular carcinoma cells in vitro / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To construct a recombinant lentivirus vector containing fusion gene NT4-p53(N15)-Ant and transfer it into HepG2 cancer cells for gene therapy.</p><p><b>METHODS</b>The gene of p53(N15)-Ant was obtained by T-vector method. After restriction enzyme digestion, the interest gene of p53(N15)-Ant was inserted in pBV220/NT4 vector and fusion gene of NT4-p53(N15)-Ant was subcloned into the plasmid of lentivirus and cotransferred into HEK-293 cells with helper plasmid. The recombinant lentivirus was produced by homologous recombination of the above mentioned two plasmids in HEK-293 cells and its titer was measured by plaque-forming. The expression of LV. NT4-p53-Ant in transfected HepG2 cells was finally confirmed by reverse transcription polymerase chain reaction (RT-PCR) procedure. The effect of LV. NT4-p53(N15)-Ant on HepG2 cells was measured by a colorimetric 3-[4,5-dimethyl thiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. The inhibition effect on HepG2 cells of LV. NT4-p53(N15)-Ant and its potential mechanism was detected by light microscopy, electron microscopy, MTT, LDH-release assay and annexin V-PI double staining.</p><p><b>RESULTS</b>The gene of p53(N15)-Ant was confirmed by restriction enzyme digestion and DNA sequencing. High titer of the recombinant lentivirus was obtained by homologous recombination in HEK-293 cell lines (1 x 10(11) pfu/ml), and the expression of NT4-p53(N15)-Ant gene in HepG2 cells was confirmed by RT-PCR. The viability of HepG2 cells was decreased to 83.4%, 46.9% and 33.9%, at 24 h, 48 h and 72 h, respectively, after infection by LV. NT4-p53(N15)-Ant. Compared with the LV. EGFP control group, there were significant differences (P < 0.01). The LDH level in HepG2 cells infected by LV. NT4-p53(N15)-Ant at 48 h, 72 h and 96 h after infection was 682 IU/L, 815 IU/L and 979 IU/L, respectively, significantly increased than that in the LV. EGFP group (P < 0.01), indicating the cell membrane destruction.</p><p><b>CONCLUSION</b>The recombinant lentivirus vector encoding gene NT4-p53(N15)-Ant is successfully constructed in this experiment by molecular cloning and recombination in vitro techniques, and the results suggested that this fusion gene has an anti-tumor effect, which provides the basis for further research on recombinant adenovirus for cancer gene therapy.</p>

Nucleotide-sugar transporters: structure, function and roles in vivo

The glycosylation of glycoconjugates and the biosynthesis of polysaccharides depend on nucleotide-sugars which are the substrates for glycosyltransferases. A large proportion of these enzymes are located within the lumen of the Golgi apparatus as well as the endoplasmic reticulum, while many of the nucleotide-sugars are synthesized in the cytosol. Thus, nucleotide-sugars are translocated from the cytosol to the lumen of the Golgi apparatus and endoplasmic reticulum by multiple spanning domain proteins known as nucleotide-sugar transporters (NSTs). These proteins were first identified biochemically and some of them were cloned by complementation of mutants. Genome and expressed sequence tag sequencing allowed the identification of a number of sequences that may encode for NSTs in different organisms. The functional characterization of some of these genes has shown that some of them can be highly specific in their substrate specificity while others can utilize up to three different nucleotide-sugars containing the same nucleotide. Mutations in genes encoding for NSTs can lead to changes in development in Drosophila melanogaster or Caenorhabditis elegans, as well as alterations in the infectivity of Leishmania donovani. In humans, the mutation of a GDP-fucose transporter is responsible for an impaired immune response as well as retarded growth. These results suggest that, even though there appear to be a fair number of genes encoding for NSTs, they are not functionally redundant and seem to play specific roles in glycosylation.