Function of Steroidogenic Factor 1 Domains in Nuclear Localization, Transactivation, and Interaction with Transcription Factor TFIIB and c-Jun

Abstract

Normal endocrine development and function require nuclear hormone receptor SF-1 (steroidogenic factor 1). To understand the molecular mechanism of SF-1 action, we have investigated its domain function by mutagenesis and functional analyses. Our mutant studies show that the putative AF2 (activation function 2) helix located at the C-terminal end is indispensable for gene activation. SF-1 does not have an N-terminal AF1 domain. Instead, it contains a unique FP region, composed of the Ftz-F1 box and the proline cluster, after the zinc finger motif. The FP region interacts with transcription factor IIB (TFIIB) in vitro. This interaction requires residues 178-201 of TFIIB, a domain capable of binding several transcription factors. The FP region also mediates physical interaction with c-Jun, and this interaction greatly enhances SF-1 activity. The putative SF-1 ligand, 25-hydroxycholesterol, has no effects on these bindings. In addition, the Ftz-F1 box contains a bipartite nuclear localization signal (NLS). Removing the basic residues at either end of the key nuclear localization sequence NLS2.2 abolishes the nuclear transport. Expression of mutants containing only the FP region or lacking the AF2 domain blocks wild-type SF-1 activity in cells. By contrast, the mutant having a truncated nuclear localization signal lacks this dominant negative effect. These results delineate the importance of the FP and AF2 regions in nuclear localization, protein-protein interaction, and transcriptional activation.

Nuclear receptor BgFTZ‐F1 regulates molting and the timing of ecdysteroid production during nymphal development in the hemimetabolous insect Blattella germanica

“…In the case of BgFTZ-F1, the box is 100% conserved compared with those of other insect homologs, with the exception of that of B. mori (Table 1). The FTZ-F1 box extends the DNA binding site of the protein and hence increases the binding specificity (Ueda et al, 1992), and also contains putative nuclear localization signals (Li et al, 1999). Given the high conservation of the DBD and the FTZ-F1 box in BgFTZ-F1, it was not surprising that the cockroach nuclear receptor bound to the recognition element PyCAAGGPyCPu, as happens with other insect FTZ-F1 homologs (Li et al, 2000;Ueda et al, 1992).…”

A novel mutation in the accessory DNA-binding domain of human steroidogenic factor 1 causes XY gonadal dysgenesis without adrenal insufficiency

“…3B). Thus, although the p.R84C mutation is located immediately adjacent to the proposed nuclear localization sequence of SF1 (bases 89-101, (25)), it does not alter its trafficking or stability. Previous studies have confirmed the proper nuclear localization of p.G146A SF1 (20).…”

SUMO Modification of Repression Domains Modulates Function of Nuclear Receptor 5A1 (Steroidogenic Factor-1)

“…Plasmids, Recombinant Proteins, and Antibody-The following constructs have been described previously: pcDNA3.1-SF-1-HA (21), pGEX-TFIIB (8), and pS2.3H-Luc (22). Plasmids pCMV-tag2c-SUMO-1 and 5xGAL4-E1B-Luc were generously provided by Dr. H. M. Shih (National Health Research Institutes, Taiwan) and Dr. Y. S. Lin (Institute of Biomedical Sciences, Academia Sinica, Taiwan), respectively.…”

“…The C-terminal region of its DNA-binding domain is a conserved 30-amino acid basic Ftz-F1 (Fushi-tarazu factor 1) box shared by all members of the NR5 (FTZ-F1) subfamily (6,7). An FP domain (aa 78 -172), including the Ftz-F1 box and a prolinerich sequence, contains a nuclear localization signal and interacting regions for TFIIB and c-Jun and is important for the transactivation function of SF-1 (8). Unlike other nuclear receptors, SF-1 lacks the N-terminal A/B region, which usually contains the ligand-independent transactivation AF-1 domain.…”