title: Expression of granulocyte colony stimulating factor and its receptor by retinal pigment epithelial cells: a role in maintaining differentiation-competent state.
abstract: OBJECTIVE
  Granulocyte colony stimulating factor (GCSF) is a potent hematopoietic factor that stimulates the growth of neutrophil granulocyte precursors, and also regulates the differentiation and survival of neutrophils by inhibiting apoptosis. Incidentally, GCSF is also known to act as an endogenous ligand for brain cells, counteracting acute neuronal degeneration and contributing to long-term plasticity of progenitor cells after cerebral ischemia. Since GCSF was recently reported to be present in retinal ganglions, we examined its expression in retinal pigment epithelial (RPE) cells, which, together with retinal neurons, arise from the same underlying precursor cells.
  
  
  METHODS
  We used reverse transcriptase polymerase chain reaction (PCR) to assay expression of GCSF and GCSF receptor (GCSFR) genes; immunostaining and flow cytometry to assay the presence of GCSFR on cell surfaces; bromodeoxyuridine (BrdU) incorporation measurement to monitor DNA synthesis; and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to monitor cell proliferation. The effect of GCSF on differentiation of RPE cells was assessed by immunocytochemistry to detect the presence of various marker proteins.
  
  
  RESULTS
  The D407 RPE cells, as well as RPE derived from cadaver eyes, were found to express both GCSF and GCSFR. Despite the presence of the GCSF receptor, exogenously added GCSF did not result in any proliferation of these cells. We found that GCSF acts like a de-differentiating factor, maintaining RPE cells in the rounded form, and in a transdifferentiation-competent state.
  
  
  CONCLUSIONS
  The expression of GCSF and GCSFR by D407 RPE may be an important factor in RPE cell maintenance.
authors: Department of Immunopathology, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
authors: Shagun
authors: S
authors: Khera
authors: Anil
authors: A
authors: Tiwari
authors: Radhika
authors: R
authors: Srinivasan
authors: Amod
authors: A
authors: Gupta
authors: Manni
authors: M
authors: Luthra-Guptasarma
mesh_terms: D000328:Adult; D000368:Aged; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival; D004247:DNA / Q000096:biosynthesis; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000502:physiology*; D016179:Granulocyte Colony-Stimulating Factor / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D008875:Middle Aged; D012333:RNA, Messenger / Q000378:metabolism; D016188:Receptors, Granulocyte Colony-Stimulating Factor / Q000235:genetics* / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014019:Tissue Donors
chemical_list: D012333:RNA, Messenger; D016188:Receptors, Granulocyte Colony-Stimulating Factor; D016179:Granulocyte Colony-Stimulating Factor; D004247:DNA