Human brain glial cells synthesize thrombospondin

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• Thrombospondin is a glycoprotein found in various human cells, known to interact with several extracellular matrix proteins.
• Platelet-derived growth factor (PDGF) has been shown to augment thrombospondin synthesis in smooth muscle cells.

Purpose of the Study:

• To investigate the presence and synthesis of thrombospondin in astrocytic neuroglial cells.
• To determine the effect of platelet-derived growth factor on thrombospondin production by glial cells.

Main Methods:

• Heparin-Sepharose affinity chromatography and SDS-PAGE were used to isolate and characterize thrombospondin from human brain homogenates.
• Immunoblot analysis and indirect immunofluorescence were employed to detect thrombospondin in cultured human glial cells.
• Metabolic labeling and immunoprecipitation assays confirmed the synthesis of thrombospondin by glial cells.
• Enzyme-linked immunosorbent assay (ELISA) quantified the release of thrombospondin in response to PDGF stimulation.

Main Results:

• A 180-kDa polypeptide, identified as thrombospondin, was found in human brain homogenates and synthesized by cultured glial cells.
• Immunoreactive thrombospondin was detected within cultured human glial cells using immunofluorescence.
• Platelet-derived growth factor significantly stimulated the release of thrombospondin into the culture medium by up to 10-fold.
• The synthesized glial thrombospondin comigrated with platelet thrombospondin on SDS-PAGE.

Conclusions:

• Thrombospondin is present within and synthesized by astrocytic neuroglial cells in the central nervous system.
• Platelet-derived growth factor enhances thrombospondin synthesis and release from glial cells.
• Thrombospondin may play a crucial role in regulating cell-cell and cell-matrix interactions during CNS development and repair.