Activation by thyroid stimulating hormone of nerve growth factor-induced gene-B expression in thyrocytes in culture: relation with proliferation and specific gene expression.
Nerve growth factor-induced gene-B (NGFI-B) is an immediate early gene first found as a part of the PC12 cell response to NGF (Milbrandt, J., Science 238 (1987) 797-799). We have previously reported that NGFI-B mRNA is strongly upregulated by thyroid-stimulating hormone (TSH) in dog thyrocytes in culture (Pichon et al., Endocrinology 137 (1996) 4691-4698). In this study, we have analyzed the regulation of NGFI-B mRNA expression by a variety of agents acting on thyrocytes proliferation and/or differentiation. We show that: (1) the induction of NGFI-B mRNA is stronger after stimulation of the cAMP cascade, but it is not restricted to this signaling pathway; (2) the powerful mitogens for thyroid cells EGF and HGF have little or no effect on NGFI-B mRNA induction; (3) NGFI-B mRNA is induced by anisomycin at a subinhibitory concentration for protein synthesis, and is superinduced by the combination of TSH and anisomycin; this treatment decreases the TSH-induced proliferation levels, but does not inhibit the induction of some differentiation markers; and (4) both in dog and in pig thyrocytes, NGFI-B mRNA induction is observed after a variety of treatments stimulating differentiation, but without proliferative effects. Our results therefore suggest that NGFI-B mRNA induction might not be related to TSH-induced thyrocyte proliferation, but could participate in the differentiation program triggered by TSH.
Jiménez-Cervantes
C
C
Institut de Recherche Interdisciplinaire en Biologie Humaine et Nucléaire, Faculté de Médecine, Université Libre de Bruxelles, Brussels, Belgium.
Pichon
B
B
Dumont
J E
JE
Maenhaut
C
C
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D004285:Dogs; D005786:Gene Expression Regulation; D007328:Insulin / Q000172:deficiency; D008934:Mitogens / Q000494:pharmacology; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D013552:Swine; D013961:Thyroid Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013972:Thyrotropin / Q000494:pharmacology / Q000502:physiology*; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics
D004268:DNA-Binding Proteins; D007328:Insulin; D008934:Mitogens; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D014157:Transcription Factors; D013972:Thyrotropin