BMP4 knockdown of NCSCs leads to aganglionosis in the middle embryonic stage.

Transplacental bone morphogenetic protein (BMP)4 RNA interference (RNAi) is a technique used to knockdown genes in embryos. BMP4 are essential for the development of nervous system in the differentiation of neural crest stem cells (NCSCs). The failure of differentiation and migration of NCSCs may lead to aganglionosis. In the present study, pregnant mice were divided into three groups: Ringer's group, pSES group and RNAi­BMP4 group. In order to silence the BMP4 gene in the first generation (F1), 11.5 day pregnant mice were injected with the small interfering RNA BMP4 plasmid, pSES or Ringer's solution via the tail vein. Semi­quantitative reverse transcriptase­polymerase chain reaction (RT­PCR)and western blotting were employed to ensure the downregulation of BMP4. Finally, X­rays were performed following a barium enema. Aganglionosis was diagnosed by general anatomy and immunohistochemistry. Compared with the control group, transplacental RNAi was able to downregulate the BMP4­Smad4 of 11.5 day embryos, as determined by semi­quantitative RT­PCR and western blotting. The megacolons of the mice were demonstrated by X­ray and confirmed by general anatomy. Aganglionosis of colonic mucosa and submucosa were diagnosed by pathology, and immunohistochemistry. Knockdown of BMP4 in pregnant mice at the middle embryonic stage led to aganglionosis. It was therefore demonstrated that BMP­Smad was essential to the NCSCs of middle stage embryos. BMP­Smad served important roles in the generation of aganglionosis. This technique of knockdown BMP4 gene may be used to establish an aganglionosis mouse model.

[In silicon cloning of HV126, a novel human gene related to multi drug resistance in leukemia].

OBJECTIVE: To find the novel gene related to the multi-drug resistance in leukemia and explore the molecular mechanism of multi-drug resistance. METHODS: The subtracted HL-60/VCR cDNA library was generated through the suppression subtractive hybridization using the wild HL-60 cells' cDNA as target and HL-60/ ATRA cells' as driver. A novel expression sequence tag (EST) sequence, which differentially expressed in HL-60/ ATRA cell, was screened by cDNA chip. Then a novel human gene, HV126 was assembled by the EST assembly tools. Bioinformatical databases and softwares were used to analyze and predict its function. Reverse transcription-PCR (RT-PCR) was used to detect the expression of HV-126 gene in leukemia cells before and after chemotherapy. RESULTS: The full open reading frames (ORFs) of the novel EST assembled by overlapping dbEST sequences included a 1991 bp nucleic sequence, which was named HV126. The deduced amino acid sequence consisted of 365 amino acids. The sequence of the novel gene exhibited 43% homology to a known gene, which is a possible member of the death domain-flood family implicated in apoptosis and inflammation. The expression of HV126 was proved to be related to the drug sensitivity in leukemia cells by RT-PCR. CONCLUSION: HV126, the novel gene, might have roles in regulating multi-drug resistance in leukemia. Further laboratory research should be done on cloning and making clear the gene function.