LMO4 Background Information
The LIM-only (LMO) proteins, LMO1 and LMO2, are nuclear factors that are characterized by a conserved LIM domain (1). The LIM domain consists of a cysteine-rich zinc-binding motif that is present in a variety of transcription factors, including the LIM homeobox (LHX) proteins of the central nervous system that contribute to cell differentiation (2). LMO1 and LMO2 are also expressed in the adult CNS in a cell type-specific manner, where they are differentially regulated by neuronal activity and are involved in regulating the differentiated phenotype of neurons (3). LMO2 is implicated in blocking the cellular commitment towards terminal differentiation, and since it lacks a specific DNA-binding homeobox domain, LMO2 rather assembles into transcriptional regulatory complexes to mediate gene expression. (4). LIM proteins form functional heteromeric LIM complexes by interacting with the widely expressed CLIM-2 (also designated nuclear LIM interactor or LIM binding domain 1), which serves to associate LIM proteins with other transcriptional regulatory components and also enhance the nuclear retention of LIM proteins (5,8). LMO2 and a related protein LMO4 are expressed in thymic precursor cells and LMO4 is also detected in mature T cells, cranial neural crest cells, dorsal limb bud mesenchyme, motor neurons, and Schwann cell progenitors (6,7).
