Morphine treatment affects the regulation of high mobility group I-type chromosomal phosphoproteins in C6 glioma cells

High mobility group (HMG) I-type chromosomal phosphoproteins HMG I/Y and HM G I-C were investigated following morphine treatment of C6BU-1 glioma. Cell s were labelled with [P-32]-orthophosphoric acid. Electrophoretic profiles and autoradiograms of the control cells revealed the presence of HMG I and HMG I-C proteins. HMG Y was not detected. Northern blot analysis showed a s ingle HMG I/Y transcript. Treatment with morphine lowered the [P-32]-incorp oration in HMG I and HMGI-C proteins and the level of the HMG I/Y transcrip t. However, it did not change the protein ratios on the Coomassie stained g els. These results suggest that morphine may trigger independent reaction p athways affecting either transcription regulation and/or postsynthetic phos phorylation of the preexisting HMG I-type proteins. In addition, opposing c hanges in the postsynthetic phosphorylation of HMG 14 and histones H1AB wer e also noticed.