In response to proteasome dysfunction, mammalian cells upregulate gene expression by activating Nrf1. Nrf1 is an endoplasmic reticulum-resident transcription factor that continually retrotranslocated and degraded the proteasome. Upon inhibition, escapes degradation cleaved become active. However, processing enzyme for remains obscure. Here we show aspartyl protease DNA-damage inducible 1 homolog 2 (DDI2) required cleave activate Deletion of DDI2 reduced form increased full-length cytosolic...

Abstract The proteasome plays a pivotal role in protein degradation, and its impairment is associated with various pathological conditions, including neurodegenerative diseases. It well understood that Nrf1 coordinates the induction of all genes response to dysfunction. However, molecular mechanism regulating basal expression remains unclear. Here we identify transcription factor THAP1, causative gene DYT6 dystonia, as regulator activity through genome-wide genetic screen. We demonstrated...

Intracellular proteins tagged with ubiquitin chains are targeted to the 26S proteasome for degradation. The two subunits, Rpn10 and Rpn13, function as receptors of proteasome. However, differences in roles between Rpn13 mammals remains be understood. We analyzed mice deficient Rpn10. Liver-specific deletion either or showed only modest impairment, but simultaneous loss both caused severe liver injury accompanied by massive accumulation conjugates, which was recovered re-expression Rpn13....

The proteasome plays a central role in intracellular protein degradation. Age-dependent decline activity is associated with cellular senescence and organismal aging; however, the mechanism by which senescent cells remains elusive. Here, we show that nuclear foci contain exhibit liquid-like properties are formed cells. formation of senescence-associated (SANPs) dependent on ubiquitination RAD23B, similar to previously known foci, but also requires activity. RAD23B knockdown suppresses SANP...

Abstract Protein aggregation is a hallmark of neurodegenerative diseases and also observed in the brains elderly individuals without such conditions, suggesting that aging drives accumulation protein aggregates. However, comprehensive understanding age-dependent aggregates involved brain remains unclear. Here, we investigated proteins become sarkosyl-insoluble with age identified hyaluronan proteoglycan link 2 (HAPLN2), hyaluronic acid-binding extracellular matrix at nodes Ranvier, as an...

ABSTRACT The proteasome is a large multicatalytic complex conserved across eukaryotes that regulates multiple cellular processes through the degradation of ubiquitinated proteins. predominantly localized to nucleus in proliferating cells and translocates cytoplasm stationary phase. Sts1 reportedly plays vital role nuclear import during proliferation yeast Saccharomyces cerevisiae . However, mechanisms underlying cytoplasmic translocation phase remain unknown. Here, we showed ubiquitin ligase...

Protein aggregates are degraded by both the autophagy–lysosomal and ubiquitin–proteasome pathways. Macroautophagy microautophagy, two forms of pathway, widely conserved across eukaryotes. While macroautophagy has been extensively studied in context degradation protein aggregates, microautophagy remains less explored. Here, we identify UBAP1-containing ESCRT-I complex PTPN23 as new regulators for aggregated proteins through an unbiased genome-wide CRISPR knockout screen, using a cell line...

Although mechanisms for protein homeostasis in the cytosol have been studied extensively, those nucleus remain largely unknown. Here, we identified that a complex mediates export of polyubiquitinated proteins from to cytosol. UBIN, ubiquitin-associated (UBA) domain-containing protein, shuttled between and CRM1-dependent manner, despite lack intrinsic nuclear signal (NES). Instead, UBIN binding substrate transporter (POST) harboring an NES through pores. bound polyubiquitin chain its UBA...

The proteasome core particle (CP) is a cytoplasmic and nuclear protease complex comprised of two α-rings β-rings stacked in order αββα. assembly CP proceeds by ordered recruitment β-subunits on an α-ring with help chaperones PAC1-PAC2, PAC3-PAC4, UMP1. However, the mechanism formation remains unsolved. Here, we show that α4, α5, α6, α7 form intermediate as initial process assembly, which requires PAC3-PAC4. α1 α3 can be incorporated independently into α4-α7 intermediate, whereas α2...

Abstract Protein quality control is an important mechanism to maintain cellular homeostasis. Damaged proteins have be restored or eliminated by degradation, which mainly achieved molecular chaperones and the ubiquitin-proteasome system. The NAD + -dependent deacetylase Sirt1 has been reported play positive roles in regulation of homeostasis response various stresses. However, its contribution protein remains unexplored. Here we show that involved both Hsp70-dependent Hsp70-independent...

Caspases cleave over 1500 substrates in the human proteome both lethal and non-lethal scenarios. However, reports of physiological consequences substrate cleavage are limited. Additionally, manner which caspase cleaves only a subset scenario remains to be elucidated. BubR1, spindle assembly checkpoint component, is humans, function unclear. Here, we found that caspases, especially Drice, Drosophila BubR1 between N-terminal KEN box motif C-terminal kinase domain. By using proximity labelling,...

The proteasome is the proteolytic machinery at center of regulated intracellular protein degradation and participates in various cellular processes. Maintaining quality therefore important for proper cell function. It unclear, however, how proteasomes change over time aged are disposed. Here, we show that undergoes specific biochemical alterations as it ages. We generated Rpn11-Flag/enhanced green fluorescent (EGFP) tag-exchangeable knock-in mice established a method selective purification...

Abstract The proteasome degradation machinery is essential for a variety of cellular processes including senescence and T‐cell immunity. Decreased activity associated with the aging process; however, regulation in CD4 + T cells relation to unclear. Here, we show that defects induction upon receptor (TCR) stimulation underlie senescence. Proteasome dysfunction promotes senescence‐associated phenotypes, defective proliferation, cytokine production increased levels PD‐1 CD44 High cells. by TCR...

McKusick-Kaufman syndrome (MKKS) is a recessively inherited human genetic disease characterized by several developmental anomalies. Mutations in the MKKS gene also cause Bardet-Biedl (BBS), genetically heterogeneous disorder with pleiotropic symptoms. However, little known about how mutations lead to disease. Here, we show that disease-causing mutants of are rapidly degraded via ubiquitin-proteasome pathway manner dependent on HSC70 interacting protein (CHIP), chaperone-dependent ubiquitin...

Ubiquitin-mediated protein degradation plays essential roles in proteostasis and is involved the pathogenesis of neurodegenerative diseases which ubiquitin-positive aberrant proteins accumulate. However, how such are processed inside cells has not been fully explored. Here, we show that product

The proteasome is a therapeutic target in cancer, but resistance to inhibitors often develops owing the induction of compensatory pathways. Through genome-wide siRNA screen combined with RNA sequencing analysis, we identified hexokinase and downstream O-GlcNAcylation as cell survival factors under impairment. inhibition synergistically induced massive death combination inhibition. We further demonstrated that was indispensable for maintaining activity by enhancing biogenesis well degradation...

The interaction of ribosomal proteins with mRNA in the 40S initiation complex was examined by chemical cross-linking. complexes were formed incubating rat liver [(3)H]Met-tRNAi, subunits, rabbit globin mRNA, and partially purified factors reticulocytes presence guanylyl(beta, gamma-methylene)-diphosphonate. then treated 1,3-butadiene diepoxide to introduce crosslinks between proteins. covalent mRNA-protein conjugates isolated chromatography on an oligo(dT) cellulose column sodium dodecyl...

Abstract Maintaining protein homeostasis is central to cell survival. The ubiquitin–proteasome system and autophagy play pivotal roles in quality control through degradation. Activities of these degradative pathways are carefully orchestrated, up‐regulated during proteasome dysfunction for cellular homeostasis. However, the mechanism by which impairment induces compensatory has remained largely elusive. Here, we show that FAM48A mediates induction inhibition. degraded accumulates cells...