Atrial natriuretic factor (ANF) binds to thyrotropin-regulated receptors in FRTL-5 cells and increases thyroglobulin mRNA.
Thyrotropin (TSH) regulation of atrial natriuretic factor (ANF) receptors was studied in the rat thyroid follicular cell line, FRTL-5. Exposure of FRTL-5 cells to 1 mU/ml TSH for 7 days resulted in a tenfold increase in ANF receptors (Bmax = 188 fmol/mg protein) compared with control (Bmax = 18 fmol/mg protein), without affecting binding affinity. An identical treatment of porcine thyrocytes with TSH resulted in a 50% decrease in ANF binding sites. Displacement binding studies indicated that > 80% of the ANF receptors in FRTL-5 cells belong to the ANF-R1 (guanylate cyclase-coupled) receptor subtype. By contrast, > 98% of the ANF receptors in porcine thyrocytes were of the ANF-R2, or clearance, receptor subtype. Intracellular cGMP content was increased thirty-sixfold in FRTL-5 cells by 1 microM ANF, but only 2.5-fold in porcine thyrocytes. cAMP levels were unaffected by ANF in either cell type. Northern blot analysis of poly A mRNA extracted from FRTL-5 cells incubated 2 days in the presence of 100 nM ANF indicated a twofold increase in thyroglobulin mRNA content compared with control. These findings suggest that the ANF-R1 receptor, preferentially expressed in FRTL-5 cells and regulated by TSH, might play a role in regulating thyroid hormone production.
Doi
S Q
SQ
Laboratory of Metabolic Diseases, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD.
Sellitti
D F
DF
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D002460:Cell Line; D012333:RNA, Messenger / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D017461:Receptors, Atrial Natriuretic Factor / Q000378:metabolism*; D013552:Swine; D013954:Thyroglobulin / Q000235:genetics*; D013961:Thyroid Gland / Q000166:cytology / Q000378:metabolism; D013972:Thyrotropin / Q000502:physiology*
D012333:RNA, Messenger; D009320:Atrial Natriuretic Factor; D013972:Thyrotropin; D013954:Thyroglobulin; D017461:Receptors, Atrial Natriuretic Factor