Topic
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.
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TL;DR: It is demonstrated that hESCs cultured in unconditioned medium (UM) are subjected to high levels of B MP signaling activity, which is reduced in CM, and the BMP antagonist noggin synergizes with basic fibroblast growth factor (bFGF) to repress BMP signaling and sustain undifferentiated proliferation of hESC in the absence of fibroblasts or CM.
Abstract: Human embryonic stem cells (hESCs) are routinely cultured on fibroblast feeder layers or in fibroblast-conditioned medium (CM). Bone morphogenetic proteins (BMPs) have previously been shown to induce hESC differentiation, in apparent contrast to mouse embryonic stem (ES) cells, in which BMP4 synergizes with leukemia inhibitory factor (LIF) to maintain self-renewal. Here we demonstrate that hESCs cultured in unconditioned medium (UM) are subjected to high levels of BMP signaling activity, which is reduced in CM. The BMP antagonist noggin synergizes with basic fibroblast growth factor (bFGF) to repress BMP signaling and sustain undifferentiated proliferation of hESCs in the absence of fibroblasts or CM. These findings suggest a basic difference in the self-renewal mechanism between mouse and human ES cells and simplify the culture of hESCs.
1,097 citations
TL;DR: The properties of a proteinase K-like subtilase, neural apoptosis-regulated convertase 1 (NARC-1), representing the ninth member of the secretory subtilases family, are described, suggesting that NARC- 1 is implicated in the differentiation of cortical neurons.
Abstract: Seven secretory mammalian kexin-like subtilases have been identified that cleave a variety of precursor proteins at monobasic and dibasic residues. The recently characterized pyrolysin-like subtilase SKI-1 cleaves proproteins at nonbasic residues. In this work we describe the properties of a proteinase K-like subtilase, neural apoptosis-regulated convertase 1 (NARC-1), representing the ninth member of the secretory subtilase family. Biosynthetic and microsequencing analyses of WT and mutant enzyme revealed that human and mouse pro-NARC-1 are autocatalytically and intramolecularly processed into NARC-1 at the (Y,I)VV(V,L)(L,M)↓ motif, a site that is representative of its enzymic specificity. In vitro peptide processing studies and/or Ala substitutions of the P1–P5 sites suggested that hydrophobic/aliphatic residues are more critical at P1, P3, and P5 than at P2 or P4. NARC-1 expression is highest in neuroepithelioma SK-N-MCIXC, hepatic BRL-3A, and in colon carcinoma LoVo-C5 cell lines. In situ hybridization and Northern blot analyses of NARC-1 expression during development in the adult and after partial hepatectomy revealed that it is expressed in cells that have the capacity to proliferate and differentiate. These include hepatocytes, kidney mesenchymal cells, intestinal ileum, and colon epithelia as well as embryonic brain telencephalon neurons. Accordingly, transfection of NARC-1 in primary cultures of embryonic day 13.5 telencephalon cells led to enhanced recruitment of undifferentiated neural progenitor cells into the neuronal lineage, suggesting that NARC-1 is implicated in the differentiation of cortical neurons.
1,097 citations
TL;DR: It is concluded that both 70Z/3 and HeLa cells contain apparently cytosolic NF-kappa B in a form with no evident DNA-binding activity, and phorbol esters both release the inhibition of binding and cause a translocation to the nucleus.
1,095 citations
TL;DR: It is shown that HER-2/neu-mediated cell growth requires the activation of Akt, which associates with p 21Cip1/WAF1 and phosphorylates it at threonine 145, resulting in cytoplasmic localization of p21Cip 1/Waf1.
Abstract: Amplification or overexpression of HER-2/neu in cancer cells confers resistance to apoptosis and promotes cell growth. The cellular localization of p21Cip1/WAF1 has been proposed to be critical either in promoting cell survival or in inhibiting cell growth. Here we show that HER-2/neu-mediated cell growth requires the activation of Akt, which associates with p21Cip1/WAF1 and phosphorylates it at threonine 145, resulting in cytoplasmic localization of p21Cip1/WAF1. Furthermore, blocking the Akt pathway with a dominant-negative Akt mutant restores the nuclear localization and cell-growth-inhibiting activity of p21Cip1/WAF1. Our results indicate that HER-2/neu induces cytoplasmic localization of p21Cip1/WAF1 through activation of Akt to promote cell growth, which may have implications for the oncogenic activity of HER-2/neu and Akt.
1,093 citations
Journal Article•
TL;DR: The release of soluble IL 2R appears to be a characteristic marker of T lymphocyte activation and might serve an immunoregulatory function during both normal and abnormal cell growth and differentiation.
Abstract: With the use of an enzyme-linked immunoabsorbent assay to measure soluble human interleukin 2 receptors (IL 2R), certain human T cell leukemia virus I (HTLV I)-positive T cell lines were found to spontaneously release large quantities of IL 2R into culture supernatants This was not found with HTLV I-negative and IL 2 independent T cell lines, and only one of seven B cell-derived lines examined produced small amounts of IL 2R In addition to this constitutive production of soluble IL 2R by certain cell lines, normal human peripheral blood mononuclear cells (PBMC) could be induced to release soluble IL 2R by plant lectins, the murine monoclonal antibody OKT3, tetanus toxoid, and allogeneic cells Such activated cells also expressed cellular IL 2R measurable in detergent solubilized cell extracts The generation of cellular and supernatant IL 2R was: dependent on cellular activation, rapid, radioresistant (3000 rad), and inhibited by cycloheximide treatment NaDodSO4-polyacrylamide gel electrophoresis analysis of soluble IL 2R released from either the HTLV I-positive T cell line HUT 102B2 or normal phytohemagglutinin-activated PBMC demonstrated molecules of apparent Mr = 35,000 to 40,000, and 45,000 to 50,000, respectively, somewhat smaller than the mature surface receptor on these cells The release of soluble IL 2R appears to be a characteristic marker of T lymphocyte activation and might serve an immunoregulatory function during both normal and abnormal cell growth and differentiation
1,092 citations