Activated monocytes produce a variety of cytokines that are involved in inflammation, such as IL-1, TNF, chemotactic factors, transforming growth factor R, platelet-derived growth factor, and IFN-a and -Q (1). Chemotactic factors released at foci of injury or bacterial invasion are thought to mediate directed migration of leukocytes into inflammatory sites. Since the leukocyte composition of the inflammatory infiltrate depends on the temporal stage of the lesion (2) and the nature of the stimulus (3), it follows that some chemoattractants should be specific for a given type of leukocyte. We recently showed that LPS-stimulated monocytes produce a chemotactic factor that attracts neutrophils, but not monocytes (4). We purified this factor to homogeneity and described the N1-12-terminal sequence of the first 42 amino acids (5). We now report molecular cloning and sequencing ofthe full-length cDNA for this monocyte-derived neutrophil chemotactic factor (MDNCF)' and the deduced amino acid sequence of the entire molecule. Specific cDNA probes also enabled us to test the capacity of a number of cytokines to induce MDNCF mRNA expression in human PBMC. The stimulation of MDNCF mRNA expression by IL-1 and TNF suggests that the local pro-inflammatory action of these cytokines may be mediated by induction of chemotactic factor secretion. Volume 167 June 1988 1883-1893 Materials and Methods cDNA Cloning of MDNCF and Nucleotide Sequence . Normal human PBMC were first fractionated by Ficoll-Hypaque and plastic adherent cells (> 90% nonspecific esterase-positive monocytes), were cultured in RPMI-1640 medium supplemented with 1% FCS and 10 ug/ml LPS (Serotype 055:1155; Difco Laboratories Inc., Detroit, MI) for 6 h at 37°C . Total RNA
We report the cloning of a human homolog of the yeast OGGC1 gene, which encodes a DNA glycosylase that excises an oxidatively damaged form of guanine, 8-hydroxyguanine (also known as 7,8-dihydro-8-oxoguanine). Since the deduced amino acid sequence (68 amino acids) of a human expressed sequence tag, N55394, matched a short stretch of yeast OGG1 protein with greater than 40% amino acid identity, a full length cDNA clone was isolated from a HeLa cell cDNA library with the N55394 clone as a probe. The cDNA clone encodes a predicted protein of 345 amino acids which is homologous to yeast OGG1 protein throughout the entire polypeptide sequence and shares 38% amino acid identity with yeast OGG1 protein. Moreover, we found that both a human homolog and yeast OGG1 protein possess two distinct DNA binding motifs, a helix-hairpin-helix (HhH) motif and a C2H2 zinc finger like motif, and a domain homologous to human and E. coli MutY proteins. Expression of a human homolog suppressed spontaneous mutagenesis of an E. coli (mutM mutY) mutant as in the case of yeast OGG1 protein. The gene was ubiquitously expressed in a variety of human organs and mapped to chromosome 3p26.2. These results strongly suggest that the gene isolated here is a human counterpart of the yeast OGGI gene and is involved in the repair of oxidative DNA damage in human cells.
Cells are under threat of osmotic perturbation; cell volume maintenance is critical in cerebral edema, inflammation and aging, in which prominent changes in intracellular or extracellular osmolality emerge. After osmotic stress-enforced cell swelling or shrinkage, the cells regulate intracellular osmolality to recover their volume. However, the mechanisms recognizing osmotic stress remain obscured. We previously clarified that apoptosis signal-regulating kinase 3 (ASK3) bidirectionally responds to osmotic stress and regulates cell volume recovery. Here, we show that macromolecular crowding induces liquid-demixing condensates of ASK3 under hyperosmotic stress, which transduce osmosensing signal into ASK3 inactivation. A genome-wide small interfering RNA (siRNA) screen identifies an ASK3 inactivation regulator, nicotinamide phosphoribosyltransferase (NAMPT), related to poly(ADP-ribose) signaling. Furthermore, we clarify that poly(ADP-ribose) keeps ASK3 condensates in the liquid phase and enables ASK3 to become inactivated under hyperosmotic stress. Our findings demonstrate that cells rationally incorporate physicochemical phase separation into their osmosensing systems.
Cancer metastasis is the most frequent cause of death for patients with cancer. The main current treatment for cancer metastasis is chemotherapy targeting cancer cells’ ability to proliferate. However, some types of cancer cells show resistance to chemotherapy. Recently, cancer cell migration has become the subject of interest as a novel target of cancer therapy. Cell migration requires many factors, such as the cytoskeleton, cell‐matrix adhesion and cell volume regulation. Here, we focus on cell volume regulation and the role of ion/water transport systems in cell migration. Transport proteins, such as ion channels, ion carriers, and aquaporins, are indispensable for cell volume regulation under steady‐state conditions and during exposure to osmotic stress. Studies from the last ~25 years have revealed that cell volume regulation also plays an important role in the process of cell migration. Water flow in accordance with localized osmotic gradients generated by ion transport contributes to the driving force for cell migration. Moreover, it has been reported that metastatic cancer cells have higher expression of these transport proteins than nonmetastatic cancer cells. Thus, ion/water transport proteins involved in cell volume regulation and cell migration could be novel therapeutic targets for cancer metastasis. In this review, after presenting the importance of ion/water transport systems in cell volume regulation, we discuss the roles of transport proteins in a pathophysiological context, especially in the context of cancer cell migration.
21Cells are under threat of osmotic perturbation; and cell volume maintenance is critical in 22 cerebral edema, inflammation and aging, in which prominent changes in intracellular or 23 extracellular osmolality emerge. After osmotic stress-enforced cell swelling or shrinkage, 24 the cells regulate intracellular osmolality to recover their volume. However, the 25 mechanisms recognizing osmotic stress remain obscured. We previously clarified that 26 apoptosis signal-regulating kinase 3 (ASK3) bidirectionally responds to osmotic stress 27 and regulates cell volume recovery. Here, we report that macromolecular crowding 28 induces liquid-demixing condensates of ASK3 under hyperosmotic stress, which 29 transduce osmosensing signal into ASK3 inactivation. A genome-wide small interfering 30 RNA (siRNA) screen identified an ASK3 inactivation regulator, nicotinamide 31 phosphoribosyltransferase (NAMPT), related to poly(ADP-ribose) signaling. 32 Furthermore, we clarify that poly(ADP-ribose) keeps ASK3 condensates in the liquid 33 phase and enables ASK3 to become inactivated under hyperosmotic stress. Our findings 34 demonstrate that cells rationally incorporate physicochemical phase separation into their 35 osmosensing systems. 36 37 38
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