MATRIGEL INDUCES THYMOSIN BETA-4 GENE IN DIFFERENTIATING ENDOTHELIAL-CELLS

We performed differential cDNA hybridization using RNA from endothelia l cells cultured for 4 hours on either plastic or basement membrane ma trix (Matrigel), and identified early genes induced during the morphol ogical differentiation into capillary-like tubes, The mRNA for one clo ne, thymosin beta 4, was increased 5-fold. Immunostaining localized th ymosin beta 4 in vivo in both growing and mature vessels as well as in other tissues. Endothelial cells transfected with thymosin beta 4 sho wed an increased rate of attachment and spreading on matrix components , and an accelerated rate of tube formation on Matrigel. An antisense oligo to thymosin beta 4 inhibited tube formation on Matrigel, The res ults suggest that thymosin beta 4 is induced and likely involved in di fferentiating endothelial cells. Thymosin beta 4 may play a role in ve ssel formation in vivo.