CHMP2B regulates TDP-43 phosphorylation and cytotoxicity independent of autophagy via CK1

Abstract

The ESCRT protein CHMP2B and the RNA-binding protein TDP-43 are both associated with ALS and FTD. The pathogenicity of CHMP2B has mainly been considered a consequence of autophagy–endolysosomal dysfunction, whereas protein inclusions containing phosphorylated TDP-43 are a pathological hallmark of ALS and FTD. Intriguingly, TDP-43 pathology has not been associated with the FTD-causing CHMP2BIntron5 mutation. In this study, we identify CHMP2B as a modifier of TDP-43–mediated neurodegeneration in a Drosophila screen. Down-regulation of CHMP2B reduces TDP-43 phosphorylation and toxicity in flies and mammalian cells. Surprisingly, although CHMP2BIntron5 causes dramatic autophagy dysfunction, disturbance of autophagy does not alter TDP-43 phosphorylation levels. Instead, we find that inhibition of CK1, but not TTBK1/2 (all of which are kinases phosphorylating TDP-43), abolishes the modifying effect of CHMP2B on TDP-43 phosphorylation. Finally, we uncover that CHMP2B modulates CK1 protein levels by negatively regulating ubiquitination and the proteasome-mediated turnover of CK1. Together, our findings propose an autophagy-independent role and mechanism of CHMP2B in regulating CK1 abundance and TDP-43 phosphorylation.

Inhibition of the MEK/ERK pathway suppresses immune overactivation and mitigates TDP-43 toxicity in a Drosophila model of ALS

“…1 a-b’). Since TDP-43 pathology is often associated with hyperphosphorylation [ 38 , 39 ] and the phosphorylation state of TDP-43 protein is positively correlated with its toxicity [ 40 – 42 ], we focused on the fly genes encoding protein kinases and phosphatases in one set of the transgenic RNAi screen. Among them, we found that two independent RNAi lines (#28,685 and #31,184) of the gene Dsor1 , the Drosophila homologue of mammalian MEK ( dMEK ), showed dramatic suppression of the age-dependent eye degeneration of the TDP-43 flies (Fig.…”

“…To our surprise, neither the phosphorylation levels (ratio of pTDP-43 to total TDP-43) nor the abundance of pTDP-43 proteins (normalized to GAPDH) was significantly altered by RNAi- Dsor1 (Figure S 3 c, d) or RNAi- rl (Figure S 3 g, h). In addition, transgenically expressed wild-type (WT) hTDP-43 was soluble and did not result in insoluble aggregation in fly models (Figure S 3 i; and [ 42 , 44 , 45 ]), which excluded the possibility that the mitigating effect by downregulation of Dsor1 or rl was due to reducing hTDP-43 protein aggregates.…”

Roles of Pyroptosis-Related Genes in the Diagnosis and Subtype Classification of Periodontitis

“…Our study is the first to establish a PRG-based predictive nomogram model to predict the risk of periodontitis from a molecular perspective. CHMP2B, a nuclear member of the endosomal sorting required for transport complex III, is integral to endolysosomal trafficking, vesicle fusion, and autophagic degradation [ 30 ]. It resides in chromosome 3p11-12 region near VGLL3 gene, which shows amplification in diverse sarcomas [ 31 ].…”

Nuclear pore complex and nucleocytoplasmic transport disruption in neurodegeneration

“…Interestingly, CHMP2B has recently been demonstrated to regulate the phosphorylation of TDP‐43 via CK1. Moreover, knockdown of CHMP2B prevented toxicity associated with TDP‐43 overexpression in both Drosophila and mammalian cell models [167]. This observation may challenge initial documentation that TDP‐43 pathology is not a defining feature of CHMP2B FTD [159,160,163,168,169].…”