LIM domain protein Trip6 has a conserved nuclear export signal, nuclear targeting sequences, and multiple transactivation domains

Trip6 is a member of a subfamily of LIM domain proteins, including also zyx in, LPP, Ajuba, and Hic-5, which localize primarily to focal adhesion plaqu es. However, in this report, we demonstrate that Trip6 is largely in the nu cleus in cells treated with leptomycin B, suggesting that Trip6 shuttles be tween nuclear and cytoplasmic compartments and that nuclear export of Trip6 is dependent on Crm1. Consistent with this finding, we have identified a n uclear export signal (NES) in Trip6, and mutation of this NES also results in sequestration of Trip6 in the nucleus. Addition of the Trip6 NES to the nuclear v-Rel oncoprotein redirects v-Rel to the cytoplasm. Trip6 also has at least two sequences that can direct cytoplasmic beta -galactosidase to t he nucleus. Using GAL4 fusion proteins and reporter gene assays, we demonst rate that Trip6 has multiple transactivation domains, including one that ap pears to overlap with sequences of the NES. In vitro- or in vivo-synthesize d Trip6, however, does not bind to DNA-cellulose. Taken together, these res ults are consistent with Trip6, and other members of this LIM protein famil y, having a role in relaying signals between focal adhesion plaques and the nucleus. (C) 2001 Elsevier Science B.V. All rights reserved.