Fernandes Nikita, Nero Luke, Lyons Shawn M, Ivanov Pavel, Mittelmeier Telsa M, Bolger Timothy A, Buchan J Ross
Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA.
Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
Biomolecules. 2020 Sep 25;10(10):1367. doi: 10.3390/biom10101367.
Stress granules (SGs) are hypothesized to facilitate TAR DNA-binding protein 43 (TDP-43) cytoplasmic mislocalization and aggregation, which may underly amyotrophic lateral sclerosis pathology. However, much data for this hypothesis is indirect. Additionally, whether P-bodies (PBs; related mRNA-protein granules) affect TDP-43 phenotypes is unclear. Here, we determine that induction of TDP-43 expression in yeast results in the accumulation of SG-like foci that in >90% of cases become the sites where TDP-43 cytoplasmic foci first appear. Later, TDP-43 foci associate less with SGs and more with PBs, though independent TDP-43 foci also accumulate. However, depleting or over-expressing yeast SG and PB proteins reveals no consistent trend between SG or PB assembly and TDP-43 foci formation, toxicity or protein abundance. In human cells, immunostaining endogenous TDP-43 with different TDP-43 antibodies reveals distinct localization and aggregation behaviors. Following acute arsenite stress, all phospho-TDP-43 foci colocalize with SGs. Finally, formation of TDP-43 cytoplasmic foci following low-dose chronic arsenite stress is impaired, but not completely blocked, in cells. Collectively, our data suggest that SG and PB assembly may facilitate TDP-43 cytoplasmic localization and aggregation but are likely not essential for these events.
应激颗粒（SGs）被认为会促进TAR DNA结合蛋白43（TDP - 43）在细胞质中的错误定位和聚集，这可能是肌萎缩侧索硬化症病理的基础。然而，支持这一假说的许多数据都是间接的。此外，P小体（PBs；相关的mRNA - 蛋白质颗粒）是否影响TDP - 43的表型尚不清楚。在这里，我们确定在酵母中诱导TDP - 43表达会导致类似SG的病灶积累，在超过90%的情况下，这些病灶会成为TDP - 43细胞质病灶首次出现的部位。后来，TDP - 43病灶与SGs的关联减少，与PBs的关联增加，尽管独立的TDP - 43病灶也会积累。然而，耗尽或过表达酵母SG和PB蛋白后，SG或PB组装与TDP - 43病灶形成、毒性或蛋白质丰度之间没有一致的趋势。在人类细胞中，用不同的TDP - 43抗体对内源性TDP - 43进行免疫染色，显示出不同的定位和聚集行为。急性亚砷酸盐应激后，所有磷酸化TDP - 43病灶都与SGs共定位。最后，在低剂量慢性亚砷酸盐应激后，TDP - 43细胞质病灶的形成在细胞中受到损害，但并未完全阻断。总的来说，我们的数据表明，SG和PB组装可能促进TDP - 43在细胞质中的定位和聚集，但这些事件可能并非必需。
