Hiromi Hosoya

Interleukin-10 Inhibits Both Production of Cytokines and Expression of Cytokine Receptors in Microglia

Abstract: Microglia, macrophage‐like cells in the CNS, are multifunctional cells; they play an important role in removal of dead cells or their remnants by phagocytosis in the CNS degeneration and are one of important cells in the CNS cytokine network to produce and respond to a variety of cytokines. The functions of microglia are regulated by inhibitory cytokines. We have reported the expression of interleukin (IL)‐10, one of the inhibitory cytokines, and its receptor in mouse microglia; therefore, IL‐10 may affect microglial functions. In this study, we investigated the effects of IL‐10 on purified microglia in culture. IL‐10 inhibited lipopolysaccharide‐induced IL‐1β and tumor necrosis factor‐α production, lysosomal enzyme activity, and superoxide anion production in a dose‐dependent manner, but did not affect granulocyte/macrophage colony‐stimulating factor‐dependent proliferation of microglia. IL‐10 also decreased the expression of both IL‐6 receptor and lipopolysaccharide‐induced IL‐2 receptor but not IL‐4 receptor on microglia as measured by flow cytometric analysis with an indirect immunofluorescence technique. IL‐10 also decreased mRNA expression of IL‐2 and IL‐6 cytokine receptors. These results suggest that IL‐10 is a unique and potent inhibitory factor in the CNS cytokine network involved in decreasing the expression of cytokine receptors as well as cytokine production by microglia.

In addition to the ARS core, the ARS box is necessary for autonomously replicating sequences

SummaryAutonomously replicating sequences (ARSs) were cloned from nuclear and mitochondrial DNA of D. melanogaster using YIp5, which is composed of pBR322 and the yeast ura3 gene, as the cloning vector and YNN27, a Ura- yeast strain as the recipient. The nucleotide sequences of six ARSs, two from nuclear bulk, two from the nuclear 1.688 satellite, and two from mitochondorial DNA, were determined. The relationship between the transformation frequency and the inclusion of the ARS core, 5′TATT-TATAGTTTTA3′, of these fragments was analysed. All the ARSs contained an ARS core or a single base change of it. However, not all the fragments that contained a single base change of the ARS core were able to transform the recipient cells, suggesting that certain bases in the ARS core were not exchangeable. It is suggested by transformation experiments with subfragments that in addition to an ARS core, an ARS box which is located within 25 bp upstream of the ARS core and whose sequence is composed of 5′TNTGAAA 3′, is necessary for autonomous replication.

Transient expression of M-CSF is important for osteoclast-like cell differentiation in a monocytic leukemia cell line.

Cells of U937, a human monocytic leukemia cell line, differentiate into macrophages by treatment with 12‐o‐tetradecanoylphorbol‐13‐acetate (TPA), whereas cells treated with 1α,25‐dihydroxyvitamin D3 [1,25‐(OH)2D3] continue to grow without undergoing differentiation. When U937 cells were successively treated with TPA and 1,25‐(OH)2D3, tartrate‐resistant acid phosphatase‐positive multinucleated cells appeared at 5 days after the treatment. These osteoclast‐like cells released a soluble form of 45Ca from 45Ca‐labeled bone particles. These cells were not formed when the order of treatment with TPA and 1,25‐(OH)2D3 was reversed. Use of either dexamethasone or interferon‐γ (IFN‐γ) was effective in inhibiting the formation of these osteoclast‐like cells. The expression of c‐src, c‐fms, and macrophage colony stimulating factor (M‐CSF) was induced by TPA treatment; however, TPA‐induced M‐CSF gene transcription was attenuated by the subsequent addition of 1,25‐(OH)2D3. Furthermore, both dexamethasone and IFN‐γ impaired the attenuation of M‐CSF expression, suggesting that the transient expression of M‐CSF may be important for the formation of osteoclast‐like cells. J. Cell. Biochem. 64:67–76.

DETECTION OF POLYMORPHIC FGF RECEPTOR 1 MRNA IN BOVINE LENS EPITHELIUM BY PCR

The expression of FGFR 1, 2 and 3 but not FGFR 4 was detected in bovine lens epithelial cells. FGFR 1 expression of both the 2‐Ig and 3‐Ig forms was detected by a difference in the lengths of the PCR products. Furthermore, mRNA which included or excluded six nucleotides corresponding to two amino acids in the acid box region of FGFR 1 was detected by a difference in mobility of the homo‐ and hetero‐duplex strands formed in the PCR reaction.