Stability of alternatively spliced IGF-I mRNA in growth plate chondrocytes.
Insulin-like growth factor-I (IGF-I) enhances the proliferation and hypertrophy of growth plate chondrocytes leading to increased growth plate width thus promoting bone elongation. Differing quantities of the multiple IGF-I transcripts within the growth plate suggest differential regulation of IGF-I. To assess this, the relative stabilities of the 1Ea, 1Eb, and 2Ea IGF-I mRNA classes in 2-6 week old rat growth plates were evaluated. The mean estimated half-life of class 1Ea was 3.7+/-0.05 h, while classes 1Eb and 2Ea decayed gradually over the course of the experiment. Estimated half-lives for each IGF-I mRNA species were unchanged at all ages examined. Incubation with Act D enhanced the transcription of class 1Ea, 1Eb, and 2Ea mRNAs to varying degrees. This implies that the differential stability of alternative IGF-I mRNA classes may be an inherent regulatory component that is not influenced by an animal's developmental state, and the differential abundance of alternative IGF-I mRNA species in the growth plate throughout development is due to transcriptional differences.
Laugero
L A
LA
Department of Animal Science, University of California, One Shields Avenue, Davis, CA 95616, USA.
Oberbauer
A M
AM
D017398:Alternative Splicing; D000818:Animals; D001846:Bone Development; D019902:Chondrocytes / Q000737:chemistry*; D004355:Drug Stability; D005456:Fluorescent Dyes; D006132:Growth Plate / Q000737:chemistry* / Q000166:cytology; D006207:Half-Life; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D016014:Linear Models; D008297:Male; D012333:RNA, Messenger / Q000032:analysis* / Q000145:classification; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
D005456:Fluorescent Dyes; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I