Pluripotent stem cells secrete Activin A to improve their epiblast competency after injection into recipient embryos

It is not fully clear why there is a higher contribution of pluripotent stem cells (PSCs) to the chimera produced by injection of PSCs into 4-cell or 8-cell stage embryos compared with blastocyst injection. Here, we show that not only embryonic stem cells (ESCs) but also induced pluripotent stem cells (iPSCs) can generate F0 nearly 100% donor cell-derived mice by 4-cell stage embryo injection, and the approach has a "dose effect". Through an analysis of the PSC-secreted proteins, Activin A was found to impede epiblast (EPI) lineage development while promoting trophectoderm (TE) differentiation, resulting in replacement of the EPI lineage of host embryos with PSCs. Interestingly, the injection of ESCs into blastocysts cultured with Activin A (cultured from 4-cell stage to early blastocyst at E3.5) could increase the contribution of ESCs to the chimera. The results indicated that PSCs secrete protein Activin A to improve their EPI competency after injection into recipient embryos through influencing the development of mouse early embryos. This result is useful for optimizing the chimera production system and for a deep understanding of PSCs effects on early embryo development.

Analysis of the effect of human lymphatic endothelial cells on proteins secreted by epithelial ovarian cancer cells with lymph node-oriented metastasis / 中国肿瘤临床

Objective:This study aimed to investigate the effect of human lymphatic endothelial cells (HLECs) on proteins secreted by epithelial ovarian cancer (EOC) cells SKOV3-pm4 with highly directional lymphatic metastasis. Methods:The supernatants of the four groups of cultured cells (A, SKOV3;B, SKOV3+HLEC;C, SKOV3-PM4;and D, SKOV3-PM4+HLEC) were collected. The proteins of these cells were detected by antibody arrays and iTRAQ-2D-LC-MALDI-TOF/TOF/MS. The screened significantly differential proteins were further analyzed by bioinformatics and validated in the human serum and cell culture medium by ELISA. Results:Progranulin (GRN) and vascular endothelial growth factor A (VEGF-A) were upregulated between groups C and A. In addition, insulin-like growth factor binding protein-7 (IGFBP-7) and secreted protein acid rich in cysteine (SPARC) were downregulated between groups D and C. Comprehensive bioinformatics analysis revealed that IGFBP7 interacted with VEGFA. VEGF exhibited the highest expression in ovarian cancer and IGFBP7 exhibited the lowest expression compared with the serum of the normal control group. Statistically significant differences were observed between the two substances. Conclusion:The HLEC microenvironment is closely associated with directional metastasis in lymph nodes with differential proteins, including matricellular proteins and adhesion factors. In particular, the upregulation of VEGFA and GRN and the downregulation of SPARC and IGFBP7 were closely associated with the directional metastasis of EOC cells in lymph nodes.

Secreted proteins of normal and myc-ras oncogene transformed rat embryo fibroblasts.

Quiescent cultures of rat embryo fibroblasts synthesize and secrete several proteins in response to mitogenic stimulation. Two of these proteins have been characterized in this study and the effect of oncogenic transformation on these proteins was monitored. A serum induced 48,000 protein was shown to be related to plasminogen activator inhibitor while another serum-induced protein of Mr 45,000 was found to be an inhibitor of DNA synthesis. Transformation of rat embryo fibroblasts with oncogenes myc and ras resulted in drastic reduction in the level of these proteins. The reduced levels of protease inhibitor may be responsible for the loss of anchorage dependence of the transformed cells. The DNA synthesis inhibitor protein may act as a negative growth regulator and reduced levels of this protein in myc-ras transformed cells may accelerate the proliferation of these cells.

Secreted proteins of quiescent, serum-stimulated and over-confluent mouse embryo fibroblasts.

Quiescent and proliferating cultures of Swiss mouse embryo fibroblasts were pulse labelled with [14C]-amino acids and the newly synthesized proteins that were secreted into the medium were resolved by electrophoresis on Polyacrylafde gradient gels. Conditioned media obtained from quiescent cultures that were stimulated to grow by the addition of 20% fetal calf serum showed the presence of two unique polypeptides of molecular weights 48000 and 26000. A polypeptide of molecular weight 45000 was present in increased amounts in serum-stimulated cells than in quiescent cells. This protein was also superinduced in quiescent cells by cycloheximide treatment. Mouse embryo fibroblasts grown under over-crowded conditions secreted two proteins of molecular weights 35000 and 11000. The 35 Κ polypeptide was shown to be related to the major excreted protein of transformed cells, since it was immunoprecipitated by an antiserum to major excreted protein. These results indicate that the 48 Κ and 26 Κ proteins may be proliferation specific proteins, while the 35 Κ protein present in the conditioned media of over-confluent cells may be a marker of morphological transformation.