THE ALPHA-6-BETA-1 INTEGRIN IS A LAMININ RECEPTOR FOR DEVELOPING RETINAL NEURONS

Cultured embryionic day 6 (E6) retinal neurons respond to laminin by making use of integrin receptors. We have recently shown that the laminin binding integrin receptor alpha6beta1 is expressed in the chick retina on both retinal ganglion cells and other retinal neurons. Antibodies raised against a fusion protein containing a large fragment of the extracellular portion of the chick alpha6 integrin subunit dramatically inhibit the interactions between E6 retinal neurons and laminin. These data show that alpha6beta1 functions as a laminin receptor in these cells. In previous work we have also shown that the levels of the mRNA for alpha6 decreases dramatically in retinal ganglion cells between E6 and E12. Data presented in this paper show that the decrease in alpha6 mRNA is not prevented by ablation of the optic tectum, indicating that contact with the target is not a major cause for this decrease.