Nuclear LIM interactor, a rhombotin and LIM homeodomain interacting protein, is expressed early in neuronal development.

LIM domain-containing transcription factors, including the LIM-only rhombotins and LIM-homeodomain proteins, are crucial for cell fate determination of erythroid and neuronal lineages. The zinc-binding LIM domains mediate protein-protein interactions, and interactions between nuclear LIM proteins and transcription factors with restricted expression patterns have been demonstrated. We have isolated a novel protein, nuclear LIM interactor (NLI), that specifically associates with a single LIM domain in all nuclear LIM proteins tested. NLI is expressed in the nuclei of diverse neuronal cell types and is coexpressed with a target interactor islet-1 (Isl1) during the initial stages of motor neuron differentiation, suggesting the mutual involvement of these proteins in the differentiation process. The broad range of interactions between NLI and LIM-containing transcription factors suggests the utilization of a common mechanism to impart unique cell fate instructions. IMAGES:

含LIM结构域（LIM domain）的转录因子，包括仅含LIM结构域的菱纹蛋白（LIM-only rhombotins）以及LIM同源结构域（LIM-homeodomain）蛋白，对于红系与神经元谱系的细胞命运决定至关重要。具备锌结合能力的LIM结构域可介导蛋白质-蛋白质相互作用，目前已有研究证实核内LIM蛋白与表达模式受限的转录因子之间存在相互作用。本研究分离得到一种新型蛋白——核LIM互作蛋白（nuclear LIM interactor, NLI），它可与所有已检测的核LIM蛋白中的单个LIM结构域特异性结合。NLI在多种神经元细胞的细胞核中均有表达，并在运动神经元分化的初始阶段与其靶标互作蛋白Islet-1（Isl1）共表达，提示这两类蛋白共同参与了分化进程。NLI与含LIM结构域的转录因子之间存在广泛的相互作用，这表明该蛋白可能通过一种通用机制来传递独特的细胞命运调控指令。图像：