Endosomal transport of septin mRNAs and encoded proteins in the phytopathogen Ustilago maydis

内小体运输细胞大分子，如脂类和蛋白质。这些分子载体主要从其他膜舱接收货物。尤其是在神经元和真菌菌丝等高度极化的细胞中，内小体沿着微管穿梭，在长距离运输中执行复杂的功能。越来越多的证据表明，这些膜载体也将mRNA作为非常规货物运输。然而，对这种内体mRNA转运的确切分子功能知之甚少。在植物病原菌Ustilago maydis中，我们最近发现内体上的Septin mRNA和蛋白质运输对于菌丝生长极的Septin细丝的正确形成是重要的。我们提出了一种新的细胞生物学机制，即内小体偶联翻译，这对于内小体装载间隔素来正确组装和运输内小体是重要的。在这里，我们通过研究体内的局部翻译来挑战这一假设。此外，我们将解决是否所有四个间隔蛋白共定位内体以及细丝，并测试这是否依赖于mRNA的运输。因此，我们将在mRNA转运、膜转运和Septin生物学的分子联系方面获得新的见解。

Endosomes transport cellular macromolecules such as lipids and proteins. These molecular carriers mainly receive their cargo from other membrane compartments. Particularly in highly polarised cells like neurons and fungal hyphae, endosomes shuttle along microtubules and carry out sophisticated functions in long-distance transport. Evidence is accumulating that these membranous carriers also transport mRNAs as unconventional cargo. However, little is known about the precise molecular function of this endosomal mRNA transport. In the phytopathogen Ustilago maydis we recently discovered that septin mRNA and protein transport on endosomes is important for correct formation of septin filaments at the hyphal growth pole. We propose a novel cell biological mechanism, namely endosome-coupled translation, which is important for loading of endosomes with septins for their correct assembly and transport. Here, we challenge this hypothesis by investigating local translation in vivo. Moreover, we will address whether all four septins co-localise on endosomes as well as in filaments and test whether this is dependent of mRNA transport. Thus, we will gain new insights in the molecular connection of mRNA transport, membrane trafficking and septin biology.