Cell culture

About: Cell culture is a research topic. Over the lifetime, 133361 publications have been published within this topic receiving 5364150 citations. The topic is also known as: cell culture techniques.

Expression of an erythroid transcription factor in megakaryocytic and mast cell lineages.

Abstract: The nuclear factor GF-1 (also known as NF-E1, Eryf-1; refs 1-3 respectively) is important in regulation of the transcription of globin and other genes that are specifically expressed in erythroid cells. We have previously shown that GF-1 of both mouse and human origin is a 413-amino-acid polypeptide with two novel zinc-finger domains whose expression is restricted to erythroid cells. Using in situ hybridization of mouse bone marrow cells and northern blot analysis of purified cell populations and permanent cell lines, we show here that GF-1 is expressed in two other hematopoietic lineages, megakaryocytes and bone marrow-derived mast cells. Our findings are consistent with results from hematopoietic progenitor culture which suggest a relationship between erythroid, megakaryocytic and mast cell lineages, and imply that GF-1 is expressed in committed multipotential cells and their progeny. Hence, the mere presence of this transcription factor is unlikely to be sufficient to programme differentiation of a single haematopoietic lineage. GF-1 may regulate the transcription of not only erythroid genes, but also many genes characteristic of megakaryocytes and mast cells, or genes shared among these lineages.

The metabolism of L-arginine and its significance for the biosynthesis of endothelium-derived relaxing factor: cultured endothelial cells recycle L-citrulline to L-arginine.

Abstract: We have investigated the mechanism by which cultured endothelial cells generate L-arginine (L-Arg), the substrate for the biosynthesis of endothelium-derived relaxing factor. When Arg-depleted endothelial cells were incubated in Krebs' solution for 60 min, L-Arg levels were significantly (9.7-fold) elevated. The generation of L-Arg coincided with a substantial decrease (90%) in intracellular L-glutamine (L-Gln), whereas all other amino acids were virtually unaffected. Changes in calcium, pH, or oxygen tension had no effect on L-Arg generation, which was, however, prevented when the cells were incubated in culture medium containing L-Gln. L-Arg generated by endothelial cells labeled with L-[14C]Arg was derived from an unlabeled intracellular source, for the specific activity of the intracellular L-Arg pool decreased substantially (8.8-fold) over 60 min. Arg-depleted endothelial cells did not form urea or metabolize L-ornithine but converted L-citrulline (L-Cit) to L-Arg possibly via formation of L-argininosuccinic acid. Nondepleted cells stimulated with the calcium ionophore A23187 showed only a transient accumulation of L-Cit, indicating that L-Cit is recycled to L-Arg during the biosynthesis of endothelium-derived relaxing factor. The generation of L-Arg by Arg-depleted endothelial cells was partially (45%) blocked by protease inhibitors, and various Arg-containing dipeptides were rapidly cleaved to yield L-Arg. Thus, cultured endothelial cells recycle L-Cit to L-Arg and possibly liberate peptidyl L-Arg. The Arg-Cit cycle appears to be the equivalent in the endothelial cell to the formation of urea by the liver. The biosynthesis of endothelium-derived relaxing factor may, therefore, not only produce a powerful vasodilator but also relieve the endothelial cell of excess nitrogen.

Genetic Instability Induced by the Tumor Microenvironment

Abstract: The tumor microenvironment is characterized by regions of fluctuating hypoxia, low pH, and nutrient deprivation. To determine the genetic consequences of growth under these conditions, we used a tumorigenic cell line carrying a recoverable, chromosomally based lambda phage shuttle vector designed to report mutations without the need for genetic selection of mutant cells. The cells were grown in parallel either in culture or as tumors in nude mice. The frequency of mutations arising in cells within the tumors was found to be 5-fold higher than that in otherwise identical cells grown in culture. A distinct pattern of mutation was also seen, with significantly more deletions and transversions in the tumors than in the cell cultures. Furthermore, exposure of the cultured cells to hypoxia produced an elevated mutation frequency and a mutation pattern similar to that seen in the tumors. These results indicate that the conditions within solid tumors are mutagenic and suggest that a fundamental mechanism of tumor progression in vivo is genetic instability induced by the tumor microenvironment.

Selective Targeting of Gold Nanorods at the Mitochondria of Cancer Cells: Implications for Cancer Therapy

Abstract: We have observed that Au nanorods (NRs) have distinct effects on cell viability via killing cancer cells while posing negligible impact on normal cells and mesenchymal stem cells. Obvious differences in cellular uptake, intracellular trafficking, and susceptibility of lysosome to Au NRs by different types of cells resulted in selective accumulation of Au NRs in the mitochondria of cancer cells. Their long-term retention decreased mitochondrial membrane potential and increased reactive oxygen species level that enhances the likelihood of cell death. These findings thus provide guidance for the design of organelle-targeted nanomaterials in tumor therapy.