1,25-Dihydroxyvitamin D3 regulates tubulin expression in chick intestine.
As in many other cell types, autoregulation of tubulin synthesis is evident in the intestinal epithelium of normal (vitamin D-replete) chicks: Suppression of protein (tubulin) synthesis by cycloheximide administration in vivo resulted within 30 min in a two-fold increase in RNA hybridizing with an alpha-tubulin probe. Vitamin D status revealed an additional regulatory component. alpha-Tubulin mRNA was elevated in vitamin D-deficient (-D) chicks and those treated with 1,25(OH)2D3 for 1-10 h prior to sacrifice, but declined precipitously 15-20 h after hormone, and in normal birds. These results suggested hormonally increased tubulin levels which in turn suppressed cellular alpha-tubulin mRNA. Analyses of total tubulin levels by [3H]-colchicine binding revealed low levels of the protein(s) in -D chicks, increased levels at 1-15 h after 1,25(OH)2D3, and maximum binding at 20 h after hormone and in normal birds.
Nemere
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Division of Biomedical Sciences, University of California, Riverside 92521.
Theofan
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Norman
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D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D003078:Colchicine / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004386:Duodenum; D005786:Gene Expression Regulation / Q000187:drug effects; D007413:Intestinal Mucosa / Q000502:physiology*; D008870:Microtubules / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D013997:Time Factors; D014404:Tubulin / Q000235:genetics*
D012333:RNA, Messenger; D014404:Tubulin; D003513:Cycloheximide; D002117:Calcitriol; D003078:Colchicine