Distinct LIM domains of Hic-5/ARA55 are required for nuclear matrix targeting and glucocorticoid receptor binding and coactivation.
Hydrogen peroxide-inducible clone-5 (Hic-5), belongs to the group III LIM domain protein family and contains four carboxyl-terminal LIM domains (LIM1-LIM4). In addition to its role in focal adhesion signaling, Hic-5 acts in the nucleus as a coactivator for some steroid hormone receptors such as the glucocorticoid receptor (GR) and androgen receptor (AR). Based upon its effect on AR transactivation, Hic-5 has also been designated as ARA55. Here, we report mapping studies of Hic-5/ARA55 functional domains and establish that LIM3 and LIM4 are necessary for maximal effects on GR transactivation. However, results from yeast two-hybrid assays demonstrated that these two LIM domains together, while necessary, are not sufficient to interact with the tau2 transactivation domain of GR. LIM4 also functions as a nuclear matrix targeting sequence (NMTS) for Hic-5/ARA55, as it is both necessary and sufficient to target a heterologous protein to the nuclear matrix. Thus, as suggested from previous analysis of LIM domain-containing proteins, separate but highly related LIM domains serve distinct functions.
Guerrero-Santoro
Jennifer
J
Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Yang
Lan
L
Stallcup
Michael R
MR
DeFranco
Donald B
DB
D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D060588:LIM Domain Proteins; D009124:Muscle Proteins; D015530:Nuclear Matrix / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D015533:Transcriptional Activation; D016212:Transforming Growth Factor beta / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D016335:Zinc Fingers; D016875:tau Proteins / Q000235:genetics / Q000378:metabolism
D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D060588:LIM Domain Proteins; D009124:Muscle Proteins; D011965:Receptors, Glucocorticoid; C490351:TGFB1I1 protein, human; D016212:Transforming Growth Factor beta; C090114:cysteine and glycine-rich protein 3; D016875:tau Proteins