Biomedical subjects

C Kohchi

Publications and source records attributed to C Kohchi.

22 records · Page 2Linked to original sources

PubMedDate not supplied

Expression of tumor necrosis factor-alpha and -beta transcripts in embryonal carcinoma and trophoblast cell lines: inflammation-like state as possible regulatory mechanism for ontogenesis.

TNF-alpha and TNF-beta are both involved in inflammation which regulates homeostasis in adults. We examined the mRNA expression of TNF-alpha and TNF-beta in murine embryonal carcinoma (EC) cell lines (PCC3, PCC4, ECA2 and F9) and trophoblast cell line (PL/B6) using a combined system of reverse transcription and polymerase chain reaction. Four lines of EC cells and PL/B6 expressed mRNA of both TNFs. Moreover, mRNA expression of two types of TNF-receptor and transcription factor NF-kappa B, both of which mediate a part of the biological function of TNFs, were also detected in EC and trophoblast cells. In order to clarify whether other cytokines may form a network during embryonal development, we also examined the expression of transcripts of inflammatory cytokines produced by activated macrophages (IL-1 alpha, IL-1 beta and G-CSF) or by T lymphocytes (IL-3 and IFN-gamma) in adult. We found that no IL-1 alpha transcript was expressed in any of the cell lines examined whether differentiated or not. Contrary to this, the transcript of G-CSF was continuously expressed in all cell lines, and those of IL-1 beta, IL-3 and IFN-gamma were slightly expressed in some cell lines.

Animals↗

PubMedDate not supplied

Early embryonic cells activate the alternative complement system.

Murine embryonic stem cells, embryonic carcinoma cells and pre-implantation embryos were found to be extremely sensitive to cytolysis by normal human serum as compared to matured cells. The cytolytic activity to embryonic cells was not removed by pre-absorption of serum with spleen lymphocytes. Conditions which block both complement activation pathways or, selectively, the alternative pathway completely abrogated the activity of human serum against embryonic cells whereas the activity was retained under conditions which block the classical complement pathway, indicating that embryonic cells activate the alternative complement system (ACS). The cytotoxic effect to murine embryonic cells was reproduced using syngeneic murine serum. Concerning the mechanism of ACS-activation, the expression of regulators of complement activation and of membrane bound sialic acid was analysed. Embryonic cells express mRNA for Crry similarly to other cells but additionally express Cr2-transcripts not found in most adult cells. Embryonic cells have strikingly low levels of membrane-bound sialic acid compared to adult cells.

Animals↗

PubMedDate not supplied

Induction of differentiation in embryonic stem cells by 26-kD membrane-bound tumor necrosis factor (TNF) and 17-kD free TNF.

The biological activity of 26-kD membrane-bound tumor necrosis factor (TNF)-a in embryonal development was examined in an in vitro system using embryonic stem (ES) cells. ES cells were seeded on NIH3T3 feeder cells transformed with mouse precursor TNF-a gene to express membrane-bound TNF-a on their cell surface. The proliferation of the ES cells was reduced and differentiation was accelerated. The same effects were also observed when 17-kD free TNF-a was added to the culture medium of the ES cells. Since free TNF-a is not present during embryogenesis, these results suggest that membrane-bound TNF-a may play an important role in embryonal development through cell-cell contact.

3T3 Cells↗

PubMedDate not supplied

Selective lysis of early embryonic cells by the alternative pathway of complement--a possible mechanism for programmed cell death in embryogenesis.

Early embryonic cells and early mouse embryos were shown to activate the alternative pathway of complement, and to be highly sensitive to complement-mediated cytolysis (Kircheis et al, In Vivo 9: 85-98, 1995). Under further development embryonic cells become resistant. The induction of resistance to the alternative pathway of complement correlates with: a) altered splicing of Cr2-transcript and b) changes in the acidic glycolipids under differentiation. Early embryonic cells have low amounts of sialic acid-containing glycolipids or express mainly GM3. The induction of differentiation changes the glycolipid pattern leading to an increase in membrane-bound sialic acid. The importance of membrane-bound sialic acid in the restriction of complement activation is demonstrated by increased sensitivity to complement after pre-treatment of cells with neuraminidase. The results indicate that there is target-specific lysis of early embryonic cells by the alternative pathway of complement. Early embryonic cells activate the alternative pathway of complement by expressing activators and low levels of membrane-bound sialic acid. Induction of differentiation changes the glycolipid pattern, leading to an increase in membrane-bound sialic acid sufficient to restrict complement-activation on the cell surface.

Animals↗