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Elena Vecino, Janosch Heller, Patricia Veiga, Keith R Martin, James Fawcett, www.ehu.es/GOBE; Influence of different extracellular matrix components on the expression of integrins and regeneration of adult retinal ganglion cells. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4971.
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© ARVO (1962-2015); The Authors (2016-present)
Retinal ganglion cells (RGCs) are exposed to injury in a variety of optic nerve diseases including glaucoma. However, not all cells respond in the same way to damage and the capacity of individual RGCs to survive or regenerate is variable. In order to elucidate factors that may be important for RGC survival and regeneration we have focussed on the extracellular matrix (ECM) and RGC integrin expression. Our specific questions were: (1) Do adult RGCs express particular sets of integrins in vitro and in vivo? (2) Can the ECM influence the expression of different integrins? (3) Can the ECM affect the survival of the cells and the length or branching complexity of their neurites?
Methods Primary RGC cultures from adult rat retina were placed on glass coverslips treated with different substrates: Poly-L-Lysine (PLL), or PLL plus laminin (L), collagen I (CI), collagen IV (CIV) or fibronectin (F). After 10 days in culture, we performed double immunostaining with an antibody against bIII-Tubulin to identify the RGCs, and antibodies against the integrin subunits: αV, α1, α3, α5, β1 or β3. The number of adhering and surviving cells, the number and length of the neurites and the expression of the integrin subunits on the different substrates were analysed.
PLL and L favoured the survival of RGCs while CI provided the least favourable conditions. The type of substrate affected the number and length of neurites, L stimulated the longest growth. We found at least three different types of RGCs in terms of their capacity to regenerate and extend neurites. The expression and activity of the integrins in adult RGCs were preserved in vitro independently of the substrate in which they grew. However, the different combinations of integrins expressed within the cells growing in different substrata suggest that RGCs expressed predominantly α1β1 or α3β1 on L, α1β1 on CI and CIV, and α5β3 on F. The activity of the integrins was demonstrated by the phosphorylation of focal adhesion kinase (FAK).
In the present study we were able to show that adult rat RGCs can survive and grow in the presence of different ECM environments tested (collagen I, collagen IV, fibronectin and laminin). All RGC types expressed all integrins tested in the cell body but not with the same intensity.
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