Figure 3.
β1 integrins differentially regulate mRNA steady-state levels of β3 and β5 integrin subunits. Total RNA was isolated from 1 × 107 cultured GD25 (−/−) and GD25-β1A cells, and β3 and β5 mRNAs were evaluated by RT-PCR and Northern blot analyses as described in MATERIALS AND METHODS. (A) Duplex RT-PCR assay for the simultaneous detection of β3 and β5 mRNAs. (B) RT-PCR for β1 mRNA performed as control. Molecular size standards (123-bp DNA ladder) are shown on the left. (C) Northern blot: equal amounts of total RNA (25 μg/lane) were probed sequentially by 32P-labeled mouse integrin β3 and β5 cDNA fragments, and by a 32P-labeled β-actin probe as a control for RNA loading. Notice that the presence of β1 integrins causes a marked down-regulation of β3 and a little up-regulation of β5 mRNA expression levels.