T3 acutely increases GH mRNA translation rate and GH secretion in hypothyroid rats.
Cytoskeleton controls the stability of transcripts, by mechanisms that involve mRNAs and eEF1A attachment to it. Besides, it plays a key role in protein synthesis and secretion, which seems to be impaired in somatotrophs of hypothyroid rats, whose cytoskeleton is disarranged. This study investigated the: eEF1A and GH mRNA binding to cytoskeleton plus GH mRNA translation rate and GH secretion, in sham-operated and thyroidectomized rats treated with T3 or saline, and killed 30min thereafter. Thyroidectomy reduced: (a) pituitary F-actin content, and eEF1A plus GH mRNA binding to it; (b) GH mRNA recruitment to polysome; and (c) liver IGF-I mRNA expression, indicating that GH mRNA stability and translation rate, as well as GH secretion were impaired. T3 acutely reversed all these changes, which points toward a nongenomic action of T3 on cytoskeleton rearrangement, which might contribute to the increase on GH mRNA translation rate and GH secretion.
Silva
F Goulart da
FG
Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1524, 05508-900, São Paulo, SP, Brazil.
Giannocco
G
G
Luchessi
A D
AD
Curi
R
R
Nunes
M T
MT
D000199:Actins / Q000378:metabolism; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D013006:Growth Hormone / Q000235:genetics* / Q000378:metabolism*; D007037:Hypothyroidism / Q000235:genetics* / Q000473:pathology; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D009929:Organ Size / Q000187:drug effects; D020648:Peptide Elongation Factor 1 / Q000378:metabolism; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D011132:Polyribosomes / Q000187:drug effects / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D014176:Protein Biosynthesis / Q000187:drug effects*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014284:Triiodothyronine / Q000494:pharmacology*
D000199:Actins; D020648:Peptide Elongation Factor 1; D012333:RNA, Messenger; D014284:Triiodothyronine; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone