Technological advances over the past ten years have generated powerful
tools for parallel analysis of complex biological problems. Among
these new technologies, DNA arrays have proven to be powerful tools for
identifying changes in the levels of individual mRNA molecules during important
cellular transitions. However, cellular behavior is dictated, not
by mRNA levels, but by the proteins translated from the individual mRNA
species. We report a high-throughput method for simultaneously monitoring
the translation state and level of individual mRNA species. Messenger
RNAs from resting and mitogenically activated fibroblasts were separated,
according to degree of ribosome loading, into well-translated and under-translated
pools. cDNA probes generated from these fractions were used to interrogate
cDNA arrays. Among approximately 1200 genes analyzed, less than 1%
were found to be translationally regulated in response to mitogenic activation,
demonstrating the strong selectivity of this regulatory mechanism.
This high-throughput approach is shown to be an effective tool for superimposing
translation profile on mRNA level for large numbers of genes, as well as
for identifying translationally regulated genes for further study.