proTRH gene expression by fetal pancreatic islets in culture.
The hypothalamic tripeptide, thyrotropin-releasing hormone (TRH), has been detected in neonatal pancreatic tissue and localized by immunocytochemistry in the islets of Langerhans. To determine whether the TRH gene is expressed in islets, we have extracted RNA from cultured rat islets and probed for proTRH mRNA using a [32P]-labeled antisense RNA. Islet proTRH mRNA comigrated with the 1.6 kilobase proTRH mRNA present in the rat hypothalamus. Normalized to total RNA, islets cultured for 7 days contained at least 10 times more proTRH mRNA than day 1 whole pancreas. We conclude that pancreatic TRH is synthesized in situ in the islets of Langerhans. This is the first attempt to characterize and quantify proTRH mRNA using neoformed foetal islets. We propose that quantitative analysis of proTRH mRNA concentrations in this culture system will enable study of the direct regulation of TRH biosynthesis in the pancreas.
Aratan-Spire
S
S
Laboratory of Toxicology, Harvard School of Public Health, Boston, Massachusetts 02115.
Scharfmann
R
R
Lechan
R M
RM
Tashjian
A H
AH
D000818:Animals; D015152:Blotting, Northern; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005333:Fetus; D005786:Gene Expression Regulation; D007031:Hypothalamus / Q000378:metabolism; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism*; D010179:Pancreas / Q000378:metabolism; D011247:Pregnancy; D011498:Protein Precursors / Q000235:genetics*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D013973:Thyrotropin-Releasing Hormone / Q000235:genetics*
D011498:Protein Precursors; D012333:RNA, Messenger; D013973:Thyrotropin-Releasing Hormone; C046418:pro-thyrotropin releasing hormone; D011761:Pyrrolidonecarboxylic Acid