Biomedical subjects

Yihong Ye

Publications and source records attributed to Yihong Ye.

3 recordsLinked to original sources

PubMed2026

Cellular modifiers of TDP-43 phase transition and cytoplasmic aggregation.

RNA-binding protein TAR DNA-binding protein 43 (TDP-43) can form liquid-like nuclear assemblies whose phase behavior is thought to influence its aggregation propensity and neurotoxic activity. The mechanisms that govern the liquid-to-solid phase transition of TDP-43 remain poorly defined. Here, we combined chemical and genome-wide genetic screens to identify cellular factors that modulate the phase behavior of an RNA-binding-defective TDP-43 mutant. Our screens uncovered multiple cellular processes, including RNA splicing, protein translation, proteostasis imbalance, and nuclear export as TDP-43 phase regulators. We also developed a semi-permeabilized cell system that partially recapitulates the TDP-43 phase transition in vitro, and showed that nuclear export inhibition reshapes the nuclear environment to favor RNA-dependent liquid-liquid phase separation (LLPS) of TDP-43, which mitigates its aggregation. Nuclear export inhibition in a brain organoid model bearing an ALS-associated mutation reduces pathogenic phospho-TDP-43 accumulation. These findings identify multiple modulators of TDP-43 phase transitions in a sensitized model system and establish a framework for further dissecting the link between nuclear transport and TDP-43 phase dynamics.

DNA-Binding Proteins↗

PubMed2026

Nuclear export modulates TDP-43 phase transition and cytoplasmic aggregation.

RNA-binding protein TAR DNA-binding protein 43 (TDP-43) can form liquid-like, nuclear assemblies whose phase behavior may influence its aggregation propensity and neurotoxic activity. The mechanism(s) that modulates the transition of TDP-43 from a liquid to solid phase is poorly defined. Here we combine chemical and genome-wide genetic screenings to identify cellular factors that modulate the phase behavior of an RNA-binding defective TDP-43 mutant that mimics an Amyotrophic Lateral Sclerosis (ALS)-associated variant. Our screens uncover multiple cellular processes including RNA splicing, protein translation, proteostasis imbalance and nuclear export as TDP-43 phase regulators. Importantly, TDP-43 phase transition can be dynamically recapitulated in vitro in a semi-permeabilized cell system, which reveals that the inhibition of nuclear export reshapes the nuclear environment in favor of an RNA-dependent TDP-43 liquid-liquid phase separation (LLPS) state, which mitigates cytoplasmic TDP-43 aggregation. We validated this mechanism in a brain organoid model bearing an ALS-associated mutation, showing that nuclear export deficiency can limit pathogenic phospho-TDP-43 accumulation. These findings establish nuclear export as a key regulator of TDP-43 phase transitions and define a mechanistic framework that links altered nuclear transport and phase dynamics to TDP-43 aggregation potential.

Amyotrophic Lateral Sclerosis (ALS)↗

PubMed2024

Proteomic Characterization of Ubiquitin Carboxyl-Terminal Hydrolase 19 Deficient Cells Reveals a Role for USP19 in the Secretion of Lysosomal Proteins.

Ubiquitin carboxyl-terminal hydrolase 19 (USP19) is a unique deubiquitinase, characterized by multiple variants generated by alternative splicing. Several variants bear a C-terminal transmembrane domain that anchors them to the endoplasmic reticulum. Other than regulating protein stability by preventing proteasome degradation, USP19 has been reported to rescue substrates from endoplasmic reticulum-associated protein degradation in a catalytic-independent manner, promote autophagy, and address proteins to lysosomal degradation via endosomal microautophagy. USP19 has recently emerged as the protein responsible for the unconventional secretion of misfolded proteins including Parkinson's disease-associated protein α-synuclein. Despite mounting evidence that USP19 plays crucial roles in several biological processes, the underlying mechanisms are unclear due to lack of information on the physiological substrates of USP19. Herein, we used high-resolution quantitative proteomics to analyze changes in the secretome and cell proteome induced by the loss of USP19 to identify proteins whose secretion or turnover is regulated by USP19. We found that ablation of USP19 induced significant proteomic alterations both in and out of the cell. Loss of USP19 impaired the release of several lysosomal proteins, including legumain (LGMN) and several cathepsins. In order to understand the underlaying mechanism, we dissected the USP19-regulated secretion of LGMN in several cell types. We found that LGMN was not a deubiquitinase substrate of USP19 and that its USP19-dependent release did not require their direct interaction. LGMN secretion occurred by a mechanism that involved the Golgi apparatus, autophagosome formation, and lysosome function. This mechanism resembled the recently described "lysosomal exocytosis," by which lysosomal hydrolases are secreted, when ubiquitination of p62 is increased in cells lacking deubiquitinases such as USP15 and USP17. In conclusion, our proteomic characterization of USP19 has identified a collection of proteins in the secretome and within the cell that are regulated by USP19, which link USP19 to the secretion of lysosomal proteins, including LGMN.

Humans↗