Glaucoma-associated polymorphism M98K-OPTN sensitizes retinal cells to protein homeostasis stress through p62-mediated caspase activation.

Review of peptidomimetic vinyl sulfones targeting cysteine proteases and proteasomes.

Cholinergic input initiates or regulates prolonged neuronal activity implicated in executive attention, learning and neuroendocrine control. In the hermaphroditic sea snail, Aplysia, ionotropic acetylcholine receptors on neuroendocrine bag cell neurons trigger an ∼30-min afterdischarge that leads to egg-laying hormone secretion and reproductive behaviour. The afterdischarge is followed by an ∼18-h refractory period, where acetylcholine fails to cause further bursting. Here, we report on a similar long-term depression of acetylcholine receptors in cultured bag cell neurons. Under whole-cell voltage-clamp, the current evoked by 2-s pressure-ejections of 1mM acetylcholine exhibited persistent rundown, with partial recovery by 6 h after the first ejection and complete recovery at 24h. Consecutive applications at 3-, 10-, 30-, 60- or 90-min intervals reliably yielded ∼two-thirds of current remaining at the second ejection. Similar rundown was elicited using the cholinergic agonist tretramethylammonium, albeit at 10mM. Rundown was independent of channel gating, as the acetylcholine receptor pore-blocker hexamethonium failed to alter progression. Neither the protein kinase A blocker KT5720 nor the muscarinic receptor antagonist phenyltrimethylammonium affected rundown. However, the proteasome inhibitor lactacystin attenuated rundown, while disrupting the trans-Golgi network with brefeldin A or protein synthesis with anisomcyin prevented recovery 24h later, consistent with receptor trafficking underlying both rundown and recovery. A decrease in receptor membrane density following acetylcholine was confirmed by confocal microscopy of neurons stained with the dye-conjugated ionotropic antagonist -conotoxin ImI-ATTO Fluor-590. Hence, retrieval of receptors from the membrane mediates rundown and, analogous to the refractory period, may control the timing of reproduction. KEY POINTS: Hormone secretion from neuroendocrine cells typically requires a prolonged burst of action potentials; for example, bag cell neurons from the marine snail Aplysia trigger reproduction by the neurohaemal release of egg-laying hormone during a lengthy afterdischarge. The bag cell neuron afterdischarge is initiated by cholinergic synaptic input onto ionotropic acetylcholine receptors, but following an afterdischarge, the neurons become unresponsive to acetylcholine for many hours. We now demonstrate that, after an initial exposure to acetylcholine, a proportion of these ionotropic receptors are internalized and made unavailable, without any influence from a metabotropic counterpart. This prolonged depression of cholinergic receptors also lasts many hours and likely serves to prevent disruption of ongoing bursting and/or the amount of hormone released. Therefore, changes in the number of ionotropic receptors at the membrane may influence the timing of neuroendocrine cell activity.

Experience of bortezomib use in refractory autoimmune neurological disorders.

The circadian rhythmicity of the universal stress protein is orchestrated by the nuclear clock component CCA1 and 26S-proteasome.

N-terminal domains and site-specific glycosylation regulate the secretion of avian melanocortin inverse agonists, agouti signaling protein (ASIP) and agouti-related protein (AGRP).

ABSTRACT Background: Multiple myeloma (MM) is a plasma cell malignant tumor known for its high incidence rate. Bortezomib was the first proteasome inhibitor approved for MM. Many factors can result in bortezomib’s adverse events, influencing its continuous treatment. It remains a controversial topic requiring more evidence to support its appropriate use. Methods: The P-values of single-factor analysis between basic clinical characters and bortezomib’s adverse events were used to make a heat map, and the variables with high correlation were selected as the objects of the study. Peripheral neuropathy (PN), infection, dyspepsia and constipation were considered which were common adverse events of bortezomib. Results: The multivariate-adjusted linear regression and smooth curve fitting results showed that compared with 85 patients in intravenous (IV) arm, 70 patients in the subcutaneous (SC) arm had less adverse reaction, with no significant influence on therapy efficacy. The dosage of bortezomib in 69 MM patients was 1.0 , and 1.3 mg/m2 in 86 MM patients. As to DS stage, we found that patients with DS stage III had more severe peripheral neuropathy than patients with DS stage I. As per our findings, MM patients in the reduced dose group had higher infection rate, but the efficacy was not significantly different between the two groups. Conclusions: This observational study shows that bortezomib applied via SC injection had a lower incidence of peripheral neuropathy, infection, and dyspepsia when compared to IV injection. Patients with DS stage III had higher peripheral neuropathy adverse reactions than patients with stage I. The patients with reduced dose of bortezomib were associated with increased infection in MM patients.

Multiple myeloma (MM) remains an incurable plasma cell malignancy despite advances with proteasome inhibitors, immunomodulatory drugs, and monoclonal antibodies. Bispecific antibodies (BsAbs) have emerged as a transformative, off-the-shelf immunotherapeutic strategy that redirects immune effector cells to eliminate malignant plasma cells. The recent FDA approvals of teclistamab, talquetamab, elranatamab and linvoseltamab have reshaped the therapeutic landscape of relapsed/refractory MM (RRMM), achieving overall response rates (ORR) exceeding 60% in heavily pretreated patients. Teclistamab, targeting BCMA, demonstrated an ORR of 63%, while talquetamab, targeting GPRC5D, achieved an ORR of 74%, even in patients previously treated with T-cell redirection therapies. Elranatamab and linvoseltamab further enriched this armamentarium with comparable efficacy and favorable safety profiles. In addition to these milestones, early-phase data from emerging trispecific antibodies, such as ISB 2001, show ORRs as high as 75% and deep responses, including stringent complete responses (sCR) and minimal residual disease (MRD) negativity. This review provides an integrated analysis of BsAbs in MM, encompassing mechanisms of action, clinical development, efficacy, safety profiles, and future directions. We synthesize the latest clinical trial data, explore strategies for overcoming resistance, and discuss ongoing efforts to optimize combination regimens and sequencing. By critically evaluating these advancements, we highlight the evolving role of BsAbs and trispecific antibodies in redefining treatment paradigms, with the ultimate goal of improving patient outcomes and advancing toward a potential cure for multiple myeloma.

Atrial fibrillation (AF) is the most common sustained arrhythmia, and its initiation and progression involve multiple mechanisms, including electrical remodeling, structural remodeling, inflammatory responses, and oxidative stress. In recent years, the ubiquitin–proteasome system (UPS), a central pathway for maintaining intracellular protein homeostasis, has attracted increasing attention in the pathogenesis of AF. By regulating the degradation and expression of ion channel proteins, Ca2+-handling molecules, and pro-fibrotic signaling factors, the UPS plays a pivotal role in key pathological processes such as electrical and structural remodeling. Several E3 ubiquitin ligases (e.g., NEDD4-1/2, MuRF1, WWP1/2, TRAF6), deubiquitinating enzymes (e.g., JOSD2), and immunoproteasome subunits (e.g., β5i) have been shown to exert critical regulatory effects on atrial electrophysiological disturbances, interstitial remodeling, and inflammation. This review provides a comprehensive summary of the regulatory mechanisms of the UPS in AF-associated pathological processes, outlines potential therapeutic targets, and highlights current intervention strategies, including proteasome inhibitors, selective E3 ligase modulators, and natural compounds. Moreover, we discuss the latest advances and future perspectives regarding the application of UPS-based interventions in AF, aiming to provide theoretical foundations and research insights for the mechanistic exploration and innovative therapeutic development of AF.

ABSTRACT Proteotoxic stress, arising from conditions that cause misfolded protein accumulation, is closely linked to the pathogenesis of multiple diseases. Macroautophagy/autophagy activation is considered a compensatory mechanism to maintain protein homeostasis, but the underlying regulatory mechanisms remain incompletely understood. Here, we show that proteotoxic stress induced by proteasome inhibition, puromycin treatment, or polyglutamine-expanded HTT (huntingtin) expression promotes nuclear accumulation of TFEB and TFE3, key regulators of lysosomal biogenesis and autophagy. Mechanistically, TFEB activation under proteotoxic stress occurs independently of canonical MTORC1 inactivation mediated by TSC2 or ATF4. Instead, it involves non-canonical inhibition of MTORC1 via RRAG GTPases. Proteotoxic stress disrupts the RRAGC-TFEB interaction, preventing TFEB recruitment to lysosomes and subsequent MTORC1 phosphorylation. An activated RRAGC mutant rescues impaired lysosomal localization and nuclear accumulation of TFEB, while co-overexpression of FLCN and FNIP2, a GAP for RRAGC, partially restores stress-induced TFEB dephosphorylation. In addition, proteasome inhibition activates non-canonical autophagy. Deletion of ATG16L1 or ATG5, which blocks Atg8-familyh protein lipidation and sequesters the FLCN-FNIP2 complex, partially abolishes proteotoxic stress-induced TFEB dephosphorylation and nuclear accumulation. Together, these findings demonstrate that proteotoxic stress triggers both non-canonical autophagy and TFEB-mediated canonical autophagy, with Atg8-family protein lipidation contributing to TFEB activation. Our results provide novel insights into how proteotoxic stress engages non-canonical MTORC1 inhibition and TFEB activation, thereby enhancing understanding of cellular adaptation to proteotoxic stress.

Multiple myeloma is an increasingly treatable disease with improved survival, yet characterized by multiple subclones that drive heterogeneity and variable clinical outcomes between patients. A biomarker driven approach can help tailor treatment and improve patient outcomes. Translocation t(11;14), a primary cytogenetic abnormality present in 15-20% of myeloma patients at diagnosis, is currently the most prominent targetable lesion in myeloma. In the era of induction with proteasome inhibitor and/or immunomodulatory drugs, t(11;14) has been associated with poorer outcomes compared to other standard-risk subgroups, with shorter progression-free and overall survival. The presence of t(11;14) in myeloma cells confers increased dependence on the pro-survival BCL2 protein, thus driving its ability to evade apoptosis, and is the main biomarker predicting response to BCL2-inhibitors. This review will examine the pathogenesis and prognostic significance of t(11;14) in myeloma and the impact of concurrent high-risk cytogenetics, the mechanism of action of BCL2-inhibitors, cumulative evidence supporting its use, and proposed mechanisms of resistance. The review will also present potential future directions regarding BCL2-inhibitor based regimens and how best to position these drugs to optimize patient outcomes.

Background: The survival of newly diagnosed multiple myeloma (NDMM) has improved markedly worldwide with the introduction of proteasome inhibitors (PIs), immunomodulatory drugs (IMiDs), and anti-CD38 monoclonal antibodies. However, real-world progress among Chinese patients remains underexplored. This study evaluated 20-year survival trends in patients with NDMM treated in our institute and benchmarked them against outcomes from the Flatiron Health database in the United States. Patients and methods: Consecutive adults diagnosed with NDMM in our institute between 2003 and 2023 were retrospectively analyzed. U.S. patients were identified from the Flatiron Health database using similar inclusion criteria. Clinical characteristics, first-line regimens, and autologous stem cell transplantation (ASCT) rates were summarized. Overall survival (OS) and progression-free survival (PFS) were estimated by Kaplan-Meier methods. Results: Among 1622 Chinese and 12,582 US patients, median age was 57 vs. 68 years. The median PFS and OS of NDMM patients in our institute was 40.1 months and 99.6 months, respectively. Induction therapy in the NICHE cohort changed markedly from primarily chemo-based therapy to combined PIs + IMIDs-based treatment, whereas these treatments were used much earlier in Flatiron. Uptake of new therapies in China increased rapidly after their inclusion in national health insurance. ASCT utilization was higher overall in China (34.9% vs. 22.1%) but remained lower among patients >65 years (6.7% vs. 12.1%). Conclusions: Two decades of real-world data from a major Chinese myeloma center demonstrate substantial improvements in survival and modernization of NDMM treatment, while highlighting persistent disparities amongst older adults.

The use of proteasome inhibitors (PI) and immunomodulatory drugs (IMiD) such as lenalidomide (Len) in early lines of therapy in multiple myeloma (MM) has resulted in a high proportion of patients with relapsed or refractory multiple myeloma (RRMM) being Len-refractory. Len refractoriness is associated with inferior outcomes, constituting an unmet need in clinical practice. This retrospective single-center study aimed to provide real-world characteristics and outcomes in RRMM previously exposed to PI and Len during 1-3 prior lines of therapy (LOT), stratified by Len refractoriness. RRMM patients between Jan 2017 and May 2023 were included. We studied clinical characteristics, treatments and survival outcomes. A total of 218 patients were included (n=85 Len refractory). The median progression-free survival was 13.6 months in Len-refractory versus 14.9 months in Len non-refractory patients. The median overall survival was 20.3 months in Len refractory, and not reached in Len non-refractory patients. The overall response rates to the subsequent LOT were 58.8% and 61.7% in Len refractory and non-refractory cohorts, respectively. IMiD-based and anti-CD38 monoclonal antibody-containing regimens were the most frequent subsequent LOT, 44% and 41%, respectively. This study shows suboptimal outcomes in Len refractory RRMM patients, highlighting the need to develop effective treatment options.

Chemical investigation of an actinomycete isolated from forest soil near a royal tomb site in the Republic of Korea (Streptomyces sp. YNK18) led to the discovery of two peptides: sadoamides A (1) and B (2). Spectroscopic analysis established 1 and 2 as all-aromatic tripeptides composed of phenylalanine (Phe) and two nonproteinogenic amino acids, 4-hydroxyphenylglycine (Hpg) and β-methyltryptophan (β-MeTrp). The relative configuration of the β-MeTrp residue was determined by J-based configuration analysis utilizing coupling constants and diagnostic ROESY correlations. The absolute configurations of sadoamides were determined using the advanced Marfey's method. Both compounds effectively inhibited the proteolytic activity of purified proteasomes in vitro and cellular proteasomes in HeLa cells, with 1 exhibiting greater potency. Sadoamide A (1) stabilized the short-lived antiapoptotic protein MCL1 and exerted significant cytoprotective effects against apoptosis-inducing chemical stimuli. These findings identify sadoamides as new microbial peptides that modulate the ubiquitin-proteasome system and highlight the potential of microbial metabolites to regulate critical eukaryotic signaling pathways, including apoptosis.

The precise regulation of gene expression is fundamental to cellular homeostasis and diversity. Dysregulation of splicing has been implicated in a range of diseases, including cancer and neurodegeneration. Ubiquitin-specific protease 39 (USP39), an essential spliceosome component lacking enzymatic activity, has remained an elusive target for pharmacological intervention. Here, we report the discovery of small-molecule ligands that selectively engage with USP39 through a thiazole scaffold, primarily interacting with its zinc finger domain. Guided by AlphaFold-based structure-activity relationship studies, we designed and optimized proteolysis-targeting chimeras (PROTACs), culminating in the development of USP39_PROTAC_V1, which harnesses the von Hippel-Lindau (VHL) E3 ubiquitin ligase for targeted degradation. Biophysical and biochemical assays demonstrated potent ternary complex formation and nanomolar-range binding affinities. In cellular models, USP39_PROTACs achieved efficient degradation of USP39 at concentrations as low as 1nM, with minimal off-target effects as confirmed by proteome-wide profiling. Mechanistic studies revealed that degradation was dependent on VHL recruitment and was abrogated by proteasome or neddylation inhibition. Notably, USP39 depletion recapitulated 5'-splice-site-specific splicing patterns previously described, thereby validating both the mechanism of action and the therapeutic relevance of this approach-particularly for modulating splicing-associated disease pathways such as cancer and retinitis pigmentosa.

ABSTRACT High temperatures can harm the growth and development of plants. Autophagy, as a conserved degradation system in eukaryotic cells, is essential for plant response to stress. However, the role of CaATG6 under heat stress is unclear. In this research, we discovered that CaATG6 contains a conserved APG6 domain, and CaATG6 had a closer phylogenetic relationship to other Solanaceae homologues. Silencing of CaATG6 reduced pepper heat tolerance, while overexpression of CaATG6 in Arabidopsis enhanced the heat tolerance. CaATG6 can improve heat tolerance in plants by upregulating the expression of CaHsfA2 , CaHSP16.4 , CaHSP25.9 and CaHSP70.1 , as well as enhancing autophagy levels. Moreover, we discovered that CaATG6 interacts with CaSKIP34 , an F‐box protein of the E3 ubiquitin ligase SCF complex. Interestingly, both silencing and overexpression of CaSKIP34 reduced heat tolerance in plants. We also observed that the protein level of CaSKIP34 decreased after heat stress treatment, but this reduction was inhibited by autophagy and proteasome inhibitors. Therefore, we hypothesise that CaATG6 may regulate plant heat tolerance by modulating CaSKIP34 stability. This study offers fresh perspectives on the role of the autophagy core gene CaATG6 in thermotolerance in pepper.

Tumor cells heavily depend on proteasome-mediated protein turnover, making the proteasome an attractive therapeutic target. Clinically, proteasome inhibitors are effective against hematologic cancers but show limited success with solid tumors, and the reasons for this difference are not well understood. Activation of yes-associated protein (YAP)/TAZ, the downstream effectors of the Hippo pathway, is a key mechanism behind drug resistance in cancers. Here, we demonstrate that proteasome stress acts as an upstream signal of the Hippo pathway in solid tumor cells. When the proteasome is inhibited, RAP2 undergoes ubiquitination and becomes inactive, which in turn disrupts the RAP2-MAP4Ks-NF2-LATS1/2 signaling pathway, leading to the activation of YAP/TAZ. YAP/TAZ activation promotes cell survival and resistance to proteasome inhibitors. Conversely, blocking YAP/TAZ can overcome this resistance and restore cancer cell sensitivity to these drugs. In diffuse-type gastric cancer-an aggressive solid tumor with a poor prognosis and limited treatment options-combined inhibition of the proteasome and YAP/TAZ effectively suppresses tumor growth. Therefore, this study identifies proteasome stress as an upstream signal of the Hippo pathway and provides a mechanistic basis for combination cancer therapy.

Pancreatic cancer (PC) is characterized by high chemoresistance and poor prognosis. CUL2, a scaffold protein of E3 ubiquitin ligases, has been implicated in tumor progression, but its role in PC remains unclear. CUL2 expression was analyzed in PC tissues and cell lines using TCGA and GEO datasets, qRT-PCR, Western blot, and immunohistochemistry analysis. The biological functions of CUL2 were investigated through gain- and loss-of-function studies in vitro. The impact of CUL2 overexpression on gemcitabine sensitivity was evaluated in xenograft models. Molecular mechanisms were explored using proteasome inhibitor MG132, co-immunoprecipitation, subcellular fractionation, and ferroptosis assessment. CUL2 was significantly upregulated in PC tissues and correlated with poor prognosis. CUL2 promoted PC cell proliferation, migration, and EMT. Mechanistically, CUL2 competed with NRF2 for KEAP1 binding, thereby preventing KEAP1-mediated NRF2 degradation and promoting NRF2 nuclear translocation. CUL2 promoted oxidative stress while activating NRF2-dependent antioxidant response. The CUL2-NRF2 axis suppressed ferroptosis and conferred gemcitabine resistance in PC cells. In xenograft models, CUL2 overexpression enhanced tumor growth and attenuated gemcitabine sensitivity through NRF2-mediated ferroptosis inhibition. Our findings reveal a novel mechanism whereby CUL2 promotes PC progression and ferroptosis resistance through regulation of the KEAP1-NRF2 axis. CUL2 overexpression enhances cellular antioxidant capacity and maintains mitochondrial integrity, thereby conferring broad resistance to ferroptosis-inducing conditions. This study suggests that targeting the CUL2-NRF2 axis to enhance ferroptosis sensitivity might represent a promising therapeutic strategy for PC treatment.

Bortezomib for the treatment of anti-N-methyl-d-aspartate receptor encephalitis in a patient with psoriatic arthritis receiving adalimumab: A case report and literature review.

BackgroundActivated B-cell (ABC) diffuse large B-cell lymphoma (DLBCL) has worse outcomes than the germinal center B-cell (GCB) subtype, but underlying molecular mechanisms remain poorly understood.MethodsTranscriptomic analysis on 43 DLBCL samples (23 GCB and 20 ABC) was performed using NanoString PanCancer Immune Profiling Panel with 30 cell-of-origin genes. Tumor microenvironment characterization was performed using CIBERSORTx and gene set enrichment analysis (GSEA) deconvolution. Based on our previous findings of MAPK10 downregulation in ABC lymphomas, MAPK10 promoter methylation was studied via pyrosequencing. Prognostic biomarkers were identified using the Cox regression and least absolute shrinkage and selection operator (LASSO) regularization. Therapeutic candidates were identified through connectivity mapping.ResultsABC lymphomas showed distinct profiles with the overexpression of VTCN1, CDK4, and CXCR5 and the downregulation of MMP9 and MAPK10. GSEA revealed enrichment of inflammatory pathways with immunosuppressive signals in ABC cases. Confirming our prior observations, MAPK10 downregulation in ABC tumors was associated with promoter hypermethylation and inferior overall survival (p < 0.01). Immune deconvolution revealed greater microenvironmental diversity in ABC cases with significant eosinophil enrichment. High CD8+ T-cell abundance was associated with improved survival, particularly in ABC patients (p < 0.01). Multivariate analysis identified CCL18 as an independent adverse prognostic factor (HR: 1.87, 95% CI: 1.25–2.79, p < 0.01). Connectivity mapping identified proteasome inhibitors and CDK4/6 inhibitors as promising therapeutic candidates.ConclusionsWe validated MAPK10 promoter hypermethylation and CCL18 overexpression as prognostic biomarkers in ABC DLBCL. These findings, derived from integrative transcriptomic and immunogenomic profiling, provide clinically relevant insights into disease biology and support biomarker-guided strategies for precision treatment in aggressive B-cell lymphomas.