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The cytochrome P450 steroid hydroxylases are coordinately regulated by steroidogenic factor 1 (SF-1), a protein expressed selectively in steroidogenic cells. Based on its expression in steroidogenic tissues and DNA-binding specificity, we isolated a putative SF-1 cDNA from an adrenocortical cDNA library. As evidence that this cDNA encodes SF-1, we now show that it is selectively expressed in steroidogenic cells, that an antiserum against its protein product specifically abolishes the SF-1-related gel-shift complex, and that its coexpression increases promoter activity of the 21-hydroxylase 5'-flanking region in transfection experiments. Sequence analyses of the SF-1 cDNA revealed that it is the mouse homolog of fushi tarazu factor I (FTZ-F1), a nuclear receptor that regulates the fushi tarazu homeobox gene in Drosophila. A second FTZ-F1 homolog, embryonal long terminal repeat-binding protein (ELP), was recently isolated from embryonal carcinoma cells. SF-1 and ELP cDNAs are virtually identical for 1017 base pairs, including putative DNA-binding domains, but diverge at their 5'- and 3'-ends. One genomic clone contained both SF-1- and ELP-specific sequences, confirming their origin from a single gene. Characterization of this gene defined shared exons encoding common regions and alternative promoters and 3'-exons leading to differences between the two FTZ-F1 transcripts. We used in situ hybridization with transcript-specific probes to study the ontogeny of SF-1 and ELP expression. ELP transcripts were not detected from embryonic day 8 to adult, consistent with its previous isolation from embryonal carcinoma cells and its postulated role in early embryonic development.(ABSTRACT TRUNCATED AT 250 WORDS)

We report the effects of tetracycline analogues on cytosolic Ca2+ transients resulting from application of ionic nickel (Ni2+), a potent surrogate agonist of the osteoclast Ca2+ "receptor". Preincubation with minocycline (1 mg/l) or a chemically modified tetracycline, 4-dedimethyl-aminotetracycline (CMT-1) (1 or 10 mg/l), resulted in a significant attenuation of the magnitude of the cytosolic [Ca2+] response to an application of 5 mM-[Ni2+]. Preincubation with doxycycline (1 or 10 mg/l) failed to produce similar results. In addition, application of minocycline alone (0.1-100 mg/l) resulted in a 3.5-fold elevation of cytosolic [Ca2+]. The results suggest a novel action of tetracyclines on the osteoclast Ca2+ "receptor".

We report the effects of the tetracycline analogues 4-dedimethylaminotetracycline (CMT-1) and minocycline on osteoclast spreading and motility. Both agents influenced the morphometric descriptor of cell spread area, rho, producing cellular retraction or an R effect (half-times: 30 and 44 minutes for CMT-1 and minocycline, respectively). At the concentrations employed, the tetracycline-induced R effects were significantly slower than, but were qualitatively similar to, those resulting from Ca2+ "receptor" activation through the application of 15 mM-[Ca2+] (slopes: -1.25, -0.18, and -4.40/minute for 10 mg/l-[CMT-1], 10 mg/l-[minocycline] and 15 mM-[Ca2+], respectively). In contrast, the same tetracycline concentrations did not influence osteoclast margin ruffling activity as described by mu, a motility descriptor known to be influenced by elevations of cellular cyclic AMP. Thus, the tetracyclines exert morphometric effects comparable to changes selectively activated by occupancy of the osteoclast Ca2+ "receptor" which may act through an increase in cytosolic [Ca2+].