The multigene family of cytoplasmic intermediate filament (IF) proteins in C. elegans covers eleven members, of which four (IFA-1 to IFA-3, IFB-1), which form an obligate heteropolymeric IF system, are essential for development. The six other C. elegans IF proteins IFB-2, IFC-1, IFC-2, IFD-1, IFD-2 and IFP-1 are co-expressed in the intestinal terminal web during different developmental stages, reveal various differently penetrant RNAi phenotypes and form another heteropolymeric IFB-2/IFCDP-1 IF system in C. elegans. Interestingly, the alternatively spliced IFC-2 variant, called EXC-2, was recently found also to be needed for a normal excretory system maturation in C. elegans. In order to better understand the IFC-2 function in the nematode tissue, we retrieved from the WormBase its multiple predicted alternatively spliced transcripts and analysed them using the molecular, immunofluorescence and RNAi approaches. We found that the 21-exon long genomic fragment encodes, besides the two different intestinal IFC-2a and IFC-2b IF proteins, also the novel excretory cell/IF unrelated protein ECP-1 and probably also the large ECP-1/IFC-2 fusion protein EXC-2, which all seem to be tissue-specific regulated from different promoters. Our analyses provide a framework for investigating interactions between the novel ECP-1, EXC-2 and some other proteins, including IFs, which show a similar excretory canal phenotype and are essential for development of the C. elegans excretory cells.

秀丽隐杆线虫的胞质中间丝（IF）蛋白的多基因家族涵盖11个成员，其中四个（IFA-1至IFA-3，IFB-1）形成专性的杂聚IF系统，对开发至关重要。其他六个秀丽隐杆线虫IF蛋白IFB-2，IFC-1，IFC-2，IFD-1，IFD-2和IFP-1在不同的发育阶段共表达于肠末端网中，揭示了各种不同的渗透RNAi表型，并在秀丽隐线虫中形成另一个杂聚IFB-2 / IFCDP-1 IF系统。有趣的是，最近发现线虫的正常排泄系统成熟也需要选择性剪接的IFC-2变体EXC-2 。。为了更好地了解线虫组织中的IFC-2功能，我们从WormBase中检索了其多个预测的交替剪接转录本，并使用分子，免疫荧光和RNAi方法对其进行了分析。我们发现，这21个外显子的长基因组片段除了编码两种不同的肠道IFC-2a和IFC-2b IF蛋白外，还编码新型的分泌细胞/ IF无关蛋白ECP-1，也可能编码大的ECP-1 / IFC- 2个融合蛋白EXC-2，似乎都是由不同启动子调控的组织特异性蛋白。我们的分析为研究新型ECP-1，EXC-2与其他一些蛋白质（包括IF）之间的相互作用提供了框架，这些相互作用显示出相似的排泄管表型，对于秀丽隐杆线虫排泄细胞的发育至关重要。