QUANTITATION OF MUCIN RNA BY PCR REVEALS INDUCTION OF BOTH MUC2 AND MUC5AC MESSENGER-RNA LEVELS BY RETINOIDS

The polydispersity of most human secretory mucin messages has made the m difficult to detect specifically and quantitatively, impeding the ev aluation of the relative expression of the various mucin genes and the ir role in normal and pathological conditions. For this reason, we dev eloped competitive reverse transcriptase-polymerase chain reaction (PC R) methods to measure the airway mucins MUC2 and MUC5AC. Oligonucleoti de pairs were designed that specifically detect MUC2 and MUC5AC, as de monstrated by the size and sequence of the PCR product and the expecte d tissue distribution. The mucin oligonucleotide primers were used to synthesize internal competitive standards, called MIMIC. Using this as say, the relative expression of these messages was analyzed in retinoi d-replete or -deprived cultures of normal human tracheobronchial epith elial (NHTBE) cells. Retinoid deficiency induces squamous metaplasia i n vivo and in vitro. Consistent with these observations and in contras t to a previous report, retinoid-deprived cultures produced at least a n order of magnitude less MUC2 and MUC5AC message than retinoid-replet e cultures. In summary, this paper describes methodology that can be a pplied to the specific and quantitative measurement of mucin messages and demonstrates that, in NHTBE cells, the level of MUC2 and MUC5AC mR NA is increased by retinoids.