Analysis of steroid resistance in lymphoid cell hybrids

Abstract

In an attempt to obtain a more detailed understanding of the action of the glucocorticoid-receptor complex in mouse lymphoid cell lines, steroid sensitivity has been investigated in hybrids. Hybrids between dexamethasone (dex)-sensitive and dexamethasone-resistant (Dex^r) variants, and hybrids between different Dex^r variants were investigated. In the case of Dex^r x Dex^s hybrids, the possibility of negative complementation was tested; in the case of Dex^r x Dex^r hybrids, positive complementation was investigated. Neither positive nor negative complementation could be detected; dex sensitivity was always dominant over dex resistance. However, hybrids which contain positive receptor allele(s) segregated out Dex^r clones at higher frequencies than expected from studies of pseudodiploid cell lines. This study suggests that different mechanisms give rise to the dex-resistant phenotype in pseudodiploid lymphoid cell lines and in pseudotetraploid hybrids of these cell lines.