LRRC25 plays a key role in all-trans retinoic acid-induced granulocytic differentiation as a novel potential leukocyte differentiation antigen

Leukocyte differentiation antigens (LDAs) play important roles in the immune system, by serving as surface markers and participating in multiple biological activities, such as recognizing pathogens, mediating membrane signals, interacting with other cells or systems, and regulating cell differentiation and activation. Data mining is a powerful tool used to identify novel LDAs from whole genome. LRRC25 (leucine rich repeat-containing 25) was predicted to have a role in the function of myeloid cells by a large-scale "omics" data analysis. Further experimental validation showed that LRRC25 is highly expressed in primary myeloid cells, such as granulocytes and monocytes, and lowly/intermediately expressed in B cells, but not in T cells and almost all NK cells. It was down-regulated in multiple acute myeloid leukemia (AML) cell lines and bone marrow cells of AML patients and up-regulated after all-trans retinoic acid (ATRA)-mediated granulocytic differentiation in AML cell lines and acute promyelocytic leukemia (APL; AML-M3, FAB classification) cells. Localization analysis showed that LRRC25 is a type I transmembrane molecule. Although ectopic LRRC25 did not promote spontaneous differentiation of NB4 cells, knockdown of LRRC25 by siRNA or shRNA and knockout of LRRC25 by the CRISPR-Cas9 system attenuated ATRA-induced terminal granulocytic differentiation, and restoration of LRRC25 in knockout cells could rescue ATRA-induced granulocytic differentiation. Therefore, LRRC25, a potential leukocyte differentiation antigen, is a key regulator of ATRA-induced granulocytic differentiation.

Purification and stability studies of prokaryotic PDCD5 protein / 北京大学学报(医学版)

Objective:To set up an effective and simple purification method to obtain highly purified prokaryotic protein of PDCD5 and study its stability. Methods:Recombinant PDCD5 protein expressed in E. coli was accumulated as an inclusion body. After washing, the inclusion body was denatured, renatured, digested with thrombine and then purified by two steps of chromatography. The purity of the products was analyzed by capillary electrophoresis and the stability was identified by SDS-PAGE. Results:Capillary electrophoresis showed that the purity of protein was 100%, and molecular weight was 15 800 with pI 5.9. Further bioactivity assay indicated that the purified PDCD5 could enhance the apoptosis of HL 60 cells withdrawing cytokine, which was in a dose dependent manner. Stability analysis showed that the PDCD5 protein was sensitive to temperature and easy to degrade at 4 ℃ and 25 ℃. However, it was relatively stable at -20 ℃ or lyophilized. Conclusion:Highly purified and stable recombinant PDCD5 protein was obtained, which lays a foundation for the functional study and application investigation of PDCD5 .

Expression and purification of truncated human recombinant nuclear apoptosis-inducing factor 1 in E.coli / 中国免疫学杂志

Objective:Nuclear apoptosis-inducing factor 1(NAIF1) is a novel apoptosis gene cloned in laboratory. To analyze the binding proteins of NAIF1 by pulldown method, the fusion expression vector of truncated human nuclear apoptosis-inducing factor 1〔NAIF1(73-327)〕 was constructed, were expressed and purified the recombinant GST-NAIF1(73-327) fusion protein in E.coli.Methods:The cDNA encoding human NAIF1(73-327) was amplified by PCR and cloned into pGEX-KG vector. The GST-NAIF1(73-327) fusion protein was expressed in E.coli and purified by affinity chromatography. The purified protein was detected by SDS-PAGE, Western blot and ESI-Q-TOF-MS/MS.Results:A prokaryotic expression vector of GST-NAIF1(73-327) was constructed and the GST-NAIF1(73-327) fusion protein was expressed in E.coli at high level. SDS-PAGE analyses indicated that the purified protein was about 53 kD. Western blot and MS/MS analyses verified the recombinant fusion protein.Conclusion:An efficient method for obtaining recombinant GST-NAIF1(73-327) fusion protein had been established and it could be used for further studies on the structure and function of NAIF1.