Regulation of proteasome assembly and activity in health and disease.

The proteasome degrades most cellular proteins in a controlled and tightly regulated manner and thereby controls many processes, including cell cycle, transcription, signalling, trafficking and protein quality control. Proteasomal degradation is vital in all cells and organisms, and dysfunction or failure of proteasomal degradation is associated with diverse human diseases, including cancer and neurodegeneration. Target selection is an important and well-established way to control protein degradation. In addition, mounting evidence indicates that cells adjust proteasome-mediated degradation to their needs by regulating proteasome abundance through the coordinated expression of proteasome subunits and assembly chaperones. Central to the regulation of proteasome assembly is TOR complex 1 (TORC1), which is the master regulator of cell growth and stress. This Review discusses how proteasome assembly and the regulation of proteasomal degradation are integrated with cellular physiology, including the interplay between the proteasome and autophagy pathways. Understanding these mechanisms has potential implications for disease therapy, as the misregulation of proteasome function contributes to human diseases such as cancer and neurodegeneration.

The ribosome-associated chaperone Zuo1 controls translation upon TORC1 inhibition.

Protein requirements of eukaryotic cells are ensured by proteostasis, which is mediated by tight control of TORC1 activity. Upon TORC1 inhibition, protein degradation is increased and protein synthesis is reduced through inhibition of translation initiation to maintain cell viability. Here, we show that the ribosome-associated complex (RAC)/Ssb chaperone system, composed of the HSP70 chaperone Ssb and its HSP40 co-chaperone Zuo1, is required to maintain proteostasis and cell viability under TORC1 inhibition in Saccharomyces cerevisiae. In the absence of Zuo1, translation does not decrease in response to the loss of TORC1 activity. A functional interaction between Zuo1 and Ssb is required for proper translational control and proteostasis maintenance upon TORC1 inhibition. Furthermore, we have shown that the rapid degradation of eIF4G following TORC1 inhibition is mediated by autophagy and is prevented in zuo1Δ cells, contributing to decreased survival in these conditions. We found that autophagy is defective in zuo1Δ cells, which impedes eIF4G degradation upon TORC1 inhibition. Our findings identify an essential role for RAC/Ssb in regulating translation in response to changes in TORC1 signalling.

Distinct TORC1 signalling branches regulate Adc17 proteasome assembly chaperone expression.

When stressed, cells need to adapt their proteome to maintain protein homeostasis. This requires increased proteasome assembly. Increased proteasome assembly is dependent on increased production of proteasome assembly chaperones. In S. cerevisiae, inhibition of the growth-promoting kinase complex TORC1 causes increased proteasome assembly chaperone translation, including that of Adc17. This is dependent upon activation of the MAPKinase Mpk1 and relocalisation of assembly chaperone mRNA to patches of dense actin. We show here that TORC1 inhibition alters cell wall properties to induce these changes by activating the Cell Wall Integrity pathway through the Wsc1, Wsc3, and Wsc4 sensor proteins. We demonstrate that in isolation these signals are insufficient to drive protein expression. We identify that the TORC1-activated S6Kinase Sch9 must be inhibited as well. This work expands our knowledge on the signalling pathways which regulate proteasome assembly chaperone production.

Homoepitaxy of Boron Nitride on Exfoliated Hexagonal Boron Nitride Flakes.

Although large efforts have been made to improve the growth of hexagonal boron nitride (hBN) by heteroepitaxy, the non-native substrates remain a fundamental factor that limits the quality. This problem can be solved by homoepitaxy, which is the growth of hBN on hBN substrates. In this report, we demonstrate the homoepitaxial growth of triangular BN grains on exfoliated hBN flakes by Metal-Organic Vapor Phase Epitaxy and show by atomic force microscopy and photoluminescence that the stacking of these triangular islands can deviate from the AA' stacking of hBN. We show that the stacking order is enforced by the crystallographic direction of the edge of the exfoliated hBN flakes, with armchair edges allowing for centrosymmetric stacking, whereas zigzag edges lead to the growth of noncentrosymmetric BN polytypes. Our results indicate pathways to grow homoepitaxial BN with tunable layer stacking, which is required to induce piezoelectricity or ferroelectricity.

Onco-nephrology: Physicians' Expectations About a New Subspecialty.

INTRODUCTION: Renal events are common in cancer patients and malignancy is a prevalent complication in both patients transplanted and under kidney replacement therapy (KRT). In recent years, onco-nephrology has been developed as a subspecialty whose scope has not been well established yet. The aim of our study was to assess resident and senior physicians' knowledge and expectations about onco-nephrology. METHODS AND MATERIALS: Two anonymous self-administered online questionnaires were developed by a multidisciplinary team and distributed to French residents and senior physicians. RESULTS: Two hundred twenty-eight physicians answered the survey, including 128 (56%) nephrologists, of which 98 (43%) were senior physicians and 130 (57%) were residents. Nephrologists rated their confidence in their ability to face onco-nephrological situation at 6/10 (interquartile range (IQR) 4.0-7.0) and oncologists at 6.0/10 (5.0-7.0). Managing cancer drugs in patients on KRT or in transplanted patients and discussion about introducing dialysis in cancer patients were designated as the most challenging topics. Asking if they had received appropriate learning, residents' median agreement was ranked at 3.0/10 (2.0-4.0). Forty-six percent of the respondents considered available resources as not appropriate. Specialized onco-nephrology consultations were accessible for 21% of the respondents. Finally, respondents thought there is a strong need for a national working group (8.3/10) with 87% of them expecting new reliable guidelines. CONCLUSION: The present survey revealed physicians' expectations about onco-nephrology implementation in France. An appropriate answer could be the creation of a national working group. Therefore, GRIFON (Groupe de Recherche Interdisciplinaire en OncoNéphrologie) has recently been created.

An evolutionarily conserved pathway controls proteasome homeostasis.

The proteasome is essential for the selective degradation of most cellular proteins, but how cells maintain adequate amounts of proteasome is unclear. Here we show that there is an evolutionarily conserved signalling pathway controlling proteasome homeostasis. Central to this pathway is TORC1, the inhibition of which induced all known yeast 19S regulatory particle assembly-chaperones (RACs), as well as proteasome subunits. Downstream of TORC1 inhibition, the yeast mitogen-activated protein kinase, Mpk1, acts to increase the supply of RACs and proteasome subunits under challenging conditions in order to maintain proteasomal degradation and cell viability. This adaptive pathway was evolutionarily conserved, with mTOR and ERK5 controlling the levels of the four mammalian RACs and proteasome abundance. Thus, the central growth and stress controllers, TORC1 and Mpk1/ERK5, endow cells with a rapid and vital adaptive response to adjust proteasome abundance in response to the rising needs of cells. Enhancing this pathway may be a useful therapeutic approach for diseases resulting from impaired proteasomal degradation.

An inducible chaperone adapts proteasome assembly to stress.

The proteasome is essential for the selective degradation of most cellular proteins. To survive overwhelming demands on the proteasome arising during environmental stresses, cells increase proteasome abundance. Proteasome assembly is known to be complex. How stressed cells overcome this vital challenge is unknown. In an unbiased suppressor screen aimed at rescuing the defects of a yeast Rpt6 thermosensitive proteasome mutant, we identified a protein, hereafter named Adc17, as it functions as an ATPase dedicated chaperone. Adc17 interacts with the amino terminus of Rpt6 to assist formation of the Rpt6-Rpt3 ATPase pair, an early step in proteasome assembly. Adc17 is important for cell fitness, and its absence aggravates proteasome defects. The abundance of Adc17 increases upon proteasome stresses, and its function is crucial to maintain homeostatic proteasome levels. Thus, cells have mechanisms to adjust proteasome assembly when demands increase, and Adc17 is a critical effector of this process.

Monolayer Boron Nitride: Hyperspectral Imaging in the Deep Ultraviolet.

The optical response of 2D materials and their heterostructures is the subject of intense research with advanced investigation of the luminescence properties in devices made of exfoliated flakes of few- down to one-monolayer thickness. Despite its prevalence in 2D materials research, hexagonal boron nitride (hBN) remains unexplored in this ultimate regime because of its ultrawide bandgap of about 6 eV and the technical difficulties related to performing microscopy in the deep-ultraviolet domain. Here, we report hyperspectral imaging at wavelengths around 200 nm in exfoliated hBN at low temperature. In monolayer boron nitride, we observe direct-gap emission around 6.1 eV. In marked contrast to transition metal dichalcogenides, the photoluminescence signal is intense in few-layer hBN, a result of the near unity radiative efficiency in indirect-gap multilayer hBN.

TRAF4 promotes TGF-ß receptor signaling and drives breast cancer metastasis.

TGF-ß signaling is a therapeutic target in advanced cancers. We identified tumor necrosis factor receptor-associated factor 4 (TRAF4) as a key component mediating pro-oncogenic TGF-ß-induced SMAD and non-SMAD signaling. Upon TGF-ß stimulation, TRAF4 is recruited to the active TGF-ß receptor complex, where it antagonizes E3 ligase SMURF2 and facilitates the recruitment of deubiquitinase USP15 to the TGF-ß type I receptor (TßRI). Both processes contribute to TßRI stabilization on the plasma membrane and thereby enhance TGF-ß signaling. In addition, the TGF-ß receptor-TRAF4 interaction triggers Lys 63-linked TRAF4 polyubiquitylation and subsequent activation of the TGF-ß-activated kinase (TAK)1. TRAF4 is required for efficient TGF-ß-induced migration, epithelial-to-mesenchymal transition, and breast cancer metastasis. Elevated TRAF4 expression correlated with increased levels of phosphorylated SMAD2 and phosphorylated TAK1 as well as poor prognosis among breast cancer patients. Our results demonstrate that TRAF4 can regulate the TGF-ß pathway and is a key determinant in breast cancer pathogenesis.

Mid-infrared Polarized Emission from Black Phosphorus Light-Emitting Diodes.

We demonstrate a mid-infrared light-emitting diode based on the 2D semiconductor black phosphorus (BP). The device is composed of a mechanically exfoliated BP/molybdenum disulfide heterojunction. Under forward bias, it emits polarized electroluminescence at λ = 3.68 µm, with room-temperature internal and external quantum efficiencies of ∼1% and ∼0.03%, respectively. In our structure, outcoupling losses are dominated by radiation toward the high refractive index substrate. The ability to tune the bandgap of BP and consequently its emission wavelength with layer number, strain, and electric field make these LEDs particularly attractive for heterointegration into mid-infrared photonic platforms.

Synchronized Pulsatile Flow With Low Systolic Output From Veno-Arterial Extracorporeal Membrane Oxygenation Improves Myocardial Recovery After Experimental Cardiac Arrest in Pigs.

Circulatory failure following cardiac arrest (CA) requires catecholamine support and occasionally veno-arterial extracorporeal membrane oxygenation (vaECMO). VaECMO-generated blood flow is continuous and retrograde, increasing ventricular stroke work. Our aim was to assess the benefit of a device generating a pulsatile vaECMO flow synchronized with the heart rhythm lowering systolic vaECMO output on the left ventricular ejection fraction (LVEF) and pulmonary capillary pressure (Pcap) after CA. This experimental randomized study in pigs compared standard nonpulsatile vaECMO (control) with pulsatile synchronized vaECMO (study) group using a pulsatility-generating device. After sedation and intubation, ventricular fibrillation was induced by pacing. After 10-min ventricular fibrillation, cardiopulmonary resuscitation was performed for 20 min then vaECMO, defibrillation and 0.15 µg/kg/min intravenous epinephrine infusion were initiated. Hemodynamics, Pcap, LVEF by echocardiography and angiography were measured at baseline and every 30 min after the vaECMO start until vaECMO and epinephrine were stopped (at 120 min), and 30 min later. Baseline hemodynamics did not differ between groups; 120 min after vaECMO initiation, LVEF by echocardiography and angiography was significantly higher in the study than control group 55 ± 19% versus 34 ± 13% (P = 0.042), 50 ± 16% versus 33 ± 12% (P = 0.043), respectively. Pcap decreased from baseline by 4.2 ± 8.6 mm Hg in the study group but increased by 5.6 ± 5.9 mm Hg in the control group (P = 0.043). Thirty minutes later, LVEF remained higher in the study group 44 ± 7% versus 26 ± 11% (P = 0.008) while Pcap did not differ. A synchronized pulsatile device decreasing systolic output from vaECMO improved LVEF and Pcap in a pig model of CA and resuscitation.

TRAF4 is a novel phosphoinositide-binding protein modulating tight junctions and favoring cell migration.

Tumor necrosis factor (TNF) receptor-associated factor 4 (TRAF4) is frequently overexpressed in carcinomas, suggesting a specific role in cancer. Although TRAF4 protein is predominantly found at tight junctions (TJs) in normal mammary epithelial cells (MECs), it accumulates in the cytoplasm of malignant MECs. How TRAF4 is recruited and functions at TJs is unclear. Here we show that TRAF4 possesses a novel phosphoinositide (PIP)-binding domain crucial for its recruitment to TJs. Of interest, this property is shared by the other members of the TRAF protein family. Indeed, the TRAF domain of all TRAF proteins (TRAF1 to TRAF6) is a bona fide PIP-binding domain. Molecular and structural analyses revealed that the TRAF domain of TRAF4 exists as a trimer that binds up to three lipids using basic residues exposed at its surface. Cellular studies indicated that TRAF4 acts as a negative regulator of TJ and increases cell migration. These functions are dependent from its ability to interact with PIPs. Our results suggest that TRAF4 overexpression might contribute to breast cancer progression by destabilizing TJs and favoring cell migration.

STARD3 or STARD3NL and VAP form a novel molecular tether between late endosomes and the ER.

Inter-organelle membrane contacts sites (MCSs) are specific subcellular regions favoring the exchange of metabolites and information. We investigated the potential role of the late-endosomal membrane-anchored proteins StAR related lipid transfer domain-3 (STARD3) and STARD3 N-terminal like (STARD3NL) in the formation of MCSs involving late-endosomes (LEs). We demonstrate that both STARD3 and STARD3NL create MCSs between LEs and the endoplasmic reticulum (ER). STARD3 and STARD3NL use a conserved two phenylalanines in an acidic tract (FFAT)-motif to interact with ER-anchored VAP proteins. Together, they form an LE-ER tethering complex allowing heterologous membrane apposition. This LE-ER tethering complex affects organelle dynamics by altering the formation of endosomal tubules. An in situ proximity ligation assay between STARD3, STARD3NL and VAP proteins identified endogenous LE-ER MCS. Thus, we report here the identification of proteins involved in inter-organellar interaction.

Translation regulation in response to stress.

Cell stresses occur in a wide variety of settings: in disease, during industrial processes, and as part of normal day-to-day rhythms. Adaptation to these stresses requires cells to alter their proteome. Cells modify the proteins they synthesize to aid proteome adaptation. Changes in both mRNA transcription and translation contribute to altered protein synthesis. Here, we discuss the changes in translational mechanisms that occur following the onset of stress, and the impact these have on stress adaptation.

Proteasome assembly chaperone translation upon stress requires Ede1 phase separation at the plasma membrane.

Proteome adaptation is key to cells surviving stresses. Increased translation of proteasome assembly chaperones (PACs) is critical for increasing proteasome assembly and cell degradative capacity. The endocytic protein Ede1 recruits PAC mRNA to cortical actin patches in Saccharomyces cerevisiae for translation upon stress. We show, through genetic and pharmacological studies, that this is mediated by the capacity of Ede1 to phase separate. PAC expression is maintained when we exchange the phase separating domains from Ede1 for those of unrelated proteins. Without these phase separating regions, PAC expression is not induced upon stress, preventing increased proteasome assembly, causing cell death. This work identifies a mechanism underpinning Ede1-mediated increased translation of specific mRNAs at a time when general translation is repressed.

[Last year of residency for oncologists: Overview and perspectives]. / Premiers docteurs juniors d'oncologie médicale : état des lieux et perspectives.

CONTEXT: The reform of the third cycle of medical studies in France has introduced of the "Junior Doctor" status during the concluding year of residency. We wish to evaluate its implementation for the first promotion of medical oncology residents during 2021-2022 in correlation with the published guidelines. METHOD: AERIO conducted a cross-sectional study among French medical oncology residents. The survey was released via social networks and emails. RESULTS: Twenty-eight of 47 residents responded. The typical week involved one to two half-days of consultation, one dedicated to clinical research, one multidisciplinary team meetings, with the rest of time being occupied by day care (mostly) and hospitalization. Teaching and quality management activities were infrequent (monthly or less). The Junior Doctors rated their overall satisfaction at 8/10. A large majority (92.5 %) felt equipped to handle most of the situations they encountered. Almost all residents (92.9 %) had negotiated with their placement supervisor prior to the selection procedure. In one third of the cases (35.7 %), the principle of mismatch between the number of residents and the number of training sites was not respected. Only 42.9 % received training in scientific writing and 82.2 % of the residents agreed on the relevance of the post-internship training modules developed in other specialties. CONCLUSIONS: Junior doctors in medical oncology express overall satisfaction with this reform, which aligns with the recommendations. Nevertheless, certain concerns, such as selection procedure and inadequacy, along with areas requiring improvement, such as post-internship training and scientific writing, are clearly established.

Boron and Nitrogen Isotope Effects on Hexagonal Boron Nitride Properties.

The unique physical, mechanical, chemical, optical, and electronic properties of hexagonal boron nitride (hBN) make it a promising 2D material for electronic, optoelectronic, nanophotonic, and quantum devices. Here, the changes in hBN's properties induced by isotopic purification in both boron and nitrogen are reported. Previous studies on isotopically pure hBN have focused on purifying the boron isotope concentration in hBN from its natural concentration (≈20 at% 10 B, 80 at% 11 B) while using naturally abundant nitrogen (99.6 at% 14 N, 0.4 at% 15 N), that is, almost pure 14 N. In this study, the class of isotopically purified hBN crystals to 15 N is extended. Crystals in the four configurations, namely h10 B14 N, h11 B14 N, h10 B15 N, and h11 B15 N, are grown by the metal flux method using boron and nitrogen single isotope (> 99%) enriched sources, with nickel plus chromium as the solvent. In-depth Raman and photoluminescence spectroscopies demonstrate the high quality of the monoisotopic hBN crystals with vibrational and optical properties of the 15 N-purified crystals at the state-of-the-art of currently available 14 N-purified hBN. The growth of high-quality h10 B14 N, h11 B14 N, h10 B15 N, and h11 B15 N opens exciting perspectives for thermal conductivity control in heat management, as well as for advanced functionalities in quantum technologies.

Precision medicine for KRAS wild-type pancreatic adenocarcinomas.

BACKGROUND: KRAS mutation is the most common molecular alteration in pancreatic adenocarcinoma (PDAC), and around 10% of patients harbor KRAS wild-type tumors (KRASWT). METHODS: A retrospective chart review of clinical/molecular data was performed including all PDAC patients with a determined KRAS status (tumor molecular profiling on tissue or liquid biopsy). RESULTS: 342 patients were included with 54 KRASWT PDAC (16%) compared to 288 patients with KRASm PDAC. Median age was 61 years [IQR:54.0;67.0] and 164 pts (48%) were female. At diagnosis, KRASWT patients (63%) were more frequently diagnosed at a non-metastatic stage compared to KRASm patients (41%) (p = 0.003). Regarding metastatic sites, liver was less frequent in KRASWT (39%, p < 0.0001). Median overall survival (mOS) from initial diagnosis was significantly higher in the KRASWT group compared to KRASm (50.8 months, CI95% [32.0-NR] vs 21.1 months, CI95% [18.9-23.4] (p < 0.004 after adjustment on age, ECOG and stage at diagnosis). In first-line systemic treatment, (mostly FOLFIRINOX) progression-free survival (PFS) was also higher in KRASWT. Based on ESCAT classification, a putative actionable alteration (ESCAT I-III) was identified in 19 (36%) KRASWT pts and 46 (16%) KRASm patients (p < 0.0001) with more alterations in FGFR2, BRAF(V600E), NRTK and more MSI tumors. KRASWT harbored also fewer alterations in TP53, CDKN2A, and SMAD4. 12 KRASWT patients received a molecularly-matched treatment with clinical benefit and improved outcomes compared to KRASm patients. CONCLUSIONS: KRASWT patients display distinct disease characteristics and outcomes with prolonged overall survival. KRASWT patients also harbor more actionable molecular alterations, leading to higher survival rates after receiving molecularly matched treatments.

Inclusion of patients with chronic kidney disease in randomized phase 3 clinical trials in patients with prostate, breast, lung, and colorectal cancer.

The objective of this study was to determine the proportion of phase 3 clinical trials investigating a systemic therapy for patients with prostate, breast, lung, or colorectal cancer that excluded patients with Chronic Kidney Disease (CKD) and the exclusion criteria chosen, if any. A search was conducted using the ClinicalTrials.gov database to identify eligible studies. Of the 268 included trials, 185 (69%) had at least one renal exclusion criteria. Of these 185 trials, 116 (63%) had an undefined exclusion criterion. Only disease site was associated with exclusion of patients with CKD in the univariate analysis, but no factors in the multivariate analysis. There are several potential barriers to including patients with CKD in clinical trials. Nevertheless, solutions can be proposed to allow the inclusion of these patients. This would allow them to access to innovative therapeutic strategies, but also allow a better applicability of trial results to this patient population.

Obesity, cancer, and response to immune checkpoint inhibitors: Could the gut microbiota be the mechanistic link?

Immune checkpoint inhibitors (ICI) have deeply changed the therapeutic management of a broad spectrum of solid tumors. Recent observations showed that obese patients receiving ICIs might have better outcomes than those with normal weight, while obesity was historically associated with a worse prognosis in cancer patients. Of note, obesity is associated with alterations in the gut microbiome profile, which interacts with immune and inflammatory pathways, both at the systemic and intratumoral levels. As the influence of the gut microbiota on the response to ICI has been repeatedly reported, a specific gut microbiome profile in obese cancer patients may be involved in their better response to ICI. This review summarizes recent data on the interactions between obesity, gut microbiota, and ICIs. In addition, we highlight possible pathophysiological mechanisms supporting the hypothesis that gut microbiota could be one of the links between obesity and poor response to ICIs.