Evidence for distinct leptomeningeal cell-dependent paracrine and EGF-linked autocrine regulatory pathways for suppression of fibrillar collagens in astrocytes

Mol Cell Neurosci. 2007 Sep;36(1):71-85. doi: 10.1016/j.mcn.2007.06.002. Epub 2007 Jun 27.


A unique and unresolved property of the central nervous system is that its extracellular matrix lacks fibrillar elements. In the present report, we show that astrocytes secrete triple helices of fibrillar collagens type I, III and V in culture, while no astroglial collagen expression could be detected in vivo. We discovered two inhibitory mechanisms that could underlie this apparent discrepancy. Thus, we uncover a strong inhibitory effect of meningeal cells on astrocytic collagen expression in coculture assays. Furthermore, we present evidence that EGF-receptor activation downregulates collagen expression in astrocytes via an autocrine loop. These investigations provide a rational framework to explain why the brain is devoid of collagen fibers, which is a unique feature that characterizes the structure of the neural extracellular matrix. Moreover, fibrillar collagens were found transiently upregulated in a laser-induced cortical lesion, suggesting that these could contribute to the glial scar that inhibits axonal regeneration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Astrocytes / drug effects*
  • Astrocytes / metabolism
  • Astrocytes / radiation effects
  • Autocrine Communication / physiology*
  • Cells, Cultured
  • Cerebral Cortex / cytology
  • Coculture Techniques / methods
  • Culture Media, Conditioned / pharmacology
  • Cytokines / pharmacology
  • Epidermal Growth Factor / pharmacology*
  • Fibrillar Collagens / metabolism*
  • Gene Expression Regulation / drug effects*
  • Gene Expression Regulation / physiology
  • Lasers / adverse effects
  • Meninges / cytology*
  • RNA, Messenger / biosynthesis
  • Rats
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tyrphostins / pharmacology


  • Culture Media, Conditioned
  • Cytokines
  • Fibrillar Collagens
  • RNA, Messenger
  • Tyrphostins
  • tyrphostin A46
  • Epidermal Growth Factor