University of SaskatchewanHARVEST
  • Login
  • Submit Your Work
  • About
    • About HARVEST
    • Guidelines
    • Browse
      • All of HARVEST
      • Communities & Collections
      • By Issue Date
      • Authors
      • Titles
      • Subjects
      • This Collection
      • By Issue Date
      • Authors
      • Titles
      • Subjects
    • My Account
      • Login
      JavaScript is disabled for your browser. Some features of this site may not work without it.
      View Item 
      • HARVEST
      • Electronic Theses and Dissertations
      • Graduate Theses and Dissertations
      • View Item
      • HARVEST
      • Electronic Theses and Dissertations
      • Graduate Theses and Dissertations
      • View Item

      Signaling of stem cell factor/c-kit receptor in the regulation of microglia

      Thumbnail
      View/Open
      nq24023.pdf (5.952Mb)
      Date
      1996-01-01
      Author
      Zhang, S.-C. (Su-Chun)
      Type
      Thesis
      Degree Level
      Doctoral
      Metadata
      Show full item record
      Abstract
      Signaling between sum cell factor (SCF) produced by stroma cells and its receptor, encoded by c-kit, expressed by stem cells or progenitor cells, is required for the normal development of hematopoietic, melanogenic, and gametogenic cell lineages. SCF and c-kit are also expressed in the nervous system, but their role in the nervous system is unknown. Using immunocytochemistry, I found that SCF was produced mainly by neurons, whereas the c-kit receptor was expressed by some neurons that often make synapses with the SCF-producing neurons and by glial cells, suggesting that SCF/c-kit receptor plays a role in neuron-neuron interaction and in a paracrine interaction between the SCF-producing neurons and the c-kit-expressing glia. Microglia, isolated from neopallial cell cultures, expressed c-kit mRNA, as shown by Northern blot analysis, and protein, shown by Western blot and immunocytochemistry. The expression of c-kit receptor in microglia in culture was found to be subject to regulation by cytokines such as SCF, colony-stimulating factor-1 (CSF-1) and interferon ã (IFN-ã). Microglia in culture also expressed SCF, as demonstrated by Northern blot and immunocytochemistry. Stimulation of microglia by IFN-ã or CSF-1 upregulated SCF expression. Thus, an autocrine action through SCF and its c-kit receptor may occur in microglia, especially when microglia are stimulated by IFN-ã or CSF-1. Microglia in culture require CSF-1 for survival. Withdrawal of CSF-1 from culture medium causes microglial cell death, whereas I found that microglia were partially rescued by the addition of SCF. Moreover, at a high dosage, SCF maintained microglia in a bipolar or tripolar shape, a relatively quiescent state. Addition of SCF to microglia in culture increased the expression of mRNAs of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and ciliary neurotrophic factor (CNTF), whereas it did not affect mRNA expression of inflammatory cytokines, interleukin 1 (IL-1), tumor necrosis factor á (TNFá), and IL-6. Using a neuron-microglia co-culture system, I demonstrated that SCF-treated microglia supported cerebral cortical neuron survival and neurite outgrowth. These observations suggest that SCF maintains microglia in a quiescent state and that microglia in this state are trophic to neurons. Stimulation of microglia in culture by CSF-1 results in microglial proliferation. I found that SCF suppressed CSF-1-induced microglial proliferation in a dose-dependent manner. Stimulation of microglia by lipopolysaccharide (LPS) or IFN-ã induced significant mRNA expression of the inflammatory cytokines IL-1, TNFá, and IL-6. Addition of SCF together with IFN-ã suppressed the induction of IL-1 and TNFá mRNAs, but addition of SCF to microglia cultures increased the production of lipocortin-1 (LC-1), an anti-inflammatory cytokine. Hence, SCF in cultures of microglia suppresses the production of inflammatory cytokines and at the same time increases the production of anti-infammmatory cytokine. (Abstract shortened by UMI.)
      Degree
      Doctor of Philosophy (Ph.D.)
      Department
      Anatomy and Cell Biology
      Program
      Anatomy and Cell Biology
      Committee
      Fedoroff, Sergey
      Copyright Date
      January 1996
      URI
      http://hdl.handle.net/10388/etd-10212004-000810
      Collections
      • Graduate Theses and Dissertations
      University of Saskatchewan

      University Library

      © University of Saskatchewan
      Contact Us | Disclaimer | Privacy