Central and peripheral neurite outgrowth differs in preference for heparin-binding versus integrin-binding sequences.

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• Neurons in the central nervous system (CNS) and peripheral nervous system (PNS) exhibit differential responses to fibronectin (FN) and its fragments.
• The 33 kDa C-terminal fragment of FN is a potent promoter of CNS neurite outgrowth.

Purpose of the Study:

• To further elucidate the neurite-promoting activity of the 33 kDa FN fragment.
• To investigate the distinct mechanisms underlying CNS and PNS neuronal responses to FN fragments.

Main Methods:

• Contrasted neurite outgrowth of CNS (spinal cord) and PNS (dorsal root ganglion) neurons on synthetic peptides representing FN sequences.
• Utilized heparin-binding peptides (FN-C/H I, FN-C/H II) and an integrin-binding peptide (CS1).
• Assessed the role of integrin-mediated and proteoglycan-mediated interactions using anti-beta 1 integrin antibodies and soluble heparin.

Main Results:

• Spinal cord neurons showed maximal outgrowth on the heparin-binding peptide FN-C/H II.
• Dorsal root ganglion neurons exhibited greatest outgrowth on the integrin-binding peptide CS1.
• CNS neurite outgrowth was more sensitive to heparin than anti-beta 1 integrin, suggesting a heparin-sensitive mechanism.

Conclusions:

• CNS and PNS neurons display differing substratum preferences for FN-derived peptides.
• Neuronal interactions with the 33 kDa FN fragment involve distinct molecular mechanisms between CNS and PNS neurons.
• Heparin-sensitive pathways play a significant role in CNS neurite outgrowth on specific FN fragments.