MAEA is an E3 ubiquitin ligase promoting autophagy and maintenance of haematopoietic stem cells

Trim47 prevents hematopoietic stem cell exhaustion during stress by regulating MAVS-mediated innate immune pathway

The maintenance of hematopoietic stem cell (HSC) functional integrity is essential for effective hematopoietic regeneration when suffering from injuries. Studies have shown that the innate immune pathways play crucial roles in the stress response of HSCs, whereas how to precisely modulate these pathways is not well characterized. Here, we identify the E3 ubiquitin ligase tripartite motif-containing 47 (Trim47) as a negative regulator of the mitochondrial antiviral-signaling protein (MAVS)-mediated innate immune pathway in HSCs. We find that Trim47 is predominantly enriched in HSCs, and its deficiency impairs the function and survival of HSCs after exposure to 5-flurouracil (5-FU) and irradiation (IR). Mechanistically, Trim47 impedes the excessive activation of the innate immune signaling and inflammatory response via K48-linked ubiquitination and degradation of MAVS. Collectively, our findings demonstrate a role of Trim47 in preventing stress-induced hematopoietic failure and thus provide a promising avenue for treatment of related diseases in the clinic.

The E3 ubiquitin ligase Nedd4L preserves skeletal muscle stem cell quiescence by inhibiting their activation

Adult stem cells play a critical role in tissue repair and maintenance. In tissues with slow turnover, including skeletal muscle, these cells are maintained in a mitotically quiescent state yet remain poised to re-enter the cell cycle to replenish themselves and regenerate the tissue. Using a panomics approach we show that the PAX7/NEDD4L axis acts against muscle stem cell activation in homeostatic skeletal muscle. Our findings suggest that PAX7 transcriptionally activates the E3 ubiquitin ligase Nedd4L and that the conditional genetic deletion of Nedd4L impairs muscle stem cell quiescence, with an upregulation of cell cycle and myogenic differentiation genes. Loss of Nedd4L in muscle stem cells results in the expression of doublecortin (DCX), which is exclusively expressed during their in vivo activation. Together, these data establish that the ubiquitin proteasome system, mediated by Nedd4L, is a key contributor to the muscle stem cell quiescent state in adult mice.

mTORC1-CTLH E3 ligase regulates the degradation of HMG-CoA synthase 1 through the Pro/N-degron pathway

Mammalian target of rapamycin (mTOR) senses changes in nutrient status and stimulates the autophagic process to recycle amino acids. However, the impact of nutrient stress on protein degradation beyond autophagic turnover is incompletely understood. We report that several metabolic enzymes are proteasomal targets regulated by mTOR activity based on comparative proteome degradation analysis. In particular, 3-hydroxy-3-methylglutaryl (HMG)-coenzyme A (CoA) synthase 1 (HMGCS1), the initial enzyme in the mevalonate pathway, exhibits the most significant half-life adaptation. Degradation of HMGCS1 is regulated by the C-terminal to LisH (CTLH) E3 ligase through the Pro/N-degron motif. HMGCS1 is ubiquitylated on two C-terminal lysines during mTORC1 inhibition, and efficient degradation of HMGCS1 in cells requires a muskelin adaptor. Importantly, modulating HMGCS1 abundance has a dose-dependent impact on cell proliferation, which is restored by adding a mevalonate intermediate. Overall, our unbiased degradomics study provides new insights into mTORC1 function in cellular metabolism: mTORC1 regulates the stability of limiting metabolic enzymes through the ubiquitin system.

Ventromedial hypothalamic nucleus subset stimulates tissue thermogenesis via preoptic area outputs

OBJECTIVE

Hypothalamic signals potently stimulate energy expenditure by engaging peripheral mechanisms to restore energy homeostasis. Previous studies have identified several critical hypothalamic sites (e.g. preoptic area (POA) and ventromedial hypothalamic nucleus (VMN)) that could be part of an interconnected neurocircuit that controls tissue thermogenesis and essential for body weight control. However, the key neurocircuit that can stimulate energy expenditure has not yet been established.

METHODS

Here, we investigated the downstream mechanisms by which VMN neurons stimulate adipose tissue thermogenesis. We manipulated subsets of VMN neurons acutely as well as chronically and studied its effect on tissue thermogenesis and body weight control, using Sf1Cre and Adcyap1Cre mice and measured physiological parameters under both high-fat diet and standard chow diet conditions. To determine the node efferent to these VMN neurons, that is involved in modulating energy expenditure, we employed electrophysiology and optogenetics experiments combined with measurements using tissue-implantable temperature microchips.

RESULTS

Activation of the VMN neurons that express the steroidogenic factor 1 (Sf1; VMNSf1 neurons) reduced body weight, adiposity and increased energy expenditure in diet-induced obese mice. This function is likely mediated, at least in part, by the release of the pituitary adenylate cyclase-activating polypeptide (PACAP; encoded by the Adcyap1 gene) by the VMN neurons, since we previously demonstrated that PACAP, at the VMN, plays a key role in energy expenditure control. Thus, we then shifted focus to the subpopulation of VMNSf1 neurons that contain the neuropeptide PACAP (VMNPACAP neurons). Since the VMN neurons do not directly project to the peripheral tissues, we traced the location of the VMNPACAP neurons' efferents. We identified that VMNPACAP neurons project to and activate neurons in the caudal regions of the POA whereby these projections stimulate tissue thermogenesis in brown and beige adipose tissue. We demonstrated that selective activation of caudal POA projections from VMNPACAP neurons induces tissue thermogenesis, most potently in negative energy balance and activating these projections lead to some similar, but mostly unique, patterns of gene expression in brown and beige tissue. Finally, we demonstrated that the activation of the VMNPACAP neurons' efferents that lie at the caudal POA are necessary for inducing tissue thermogenesis in brown and beige adipose tissue.

CONCLUSIONS

These data indicate that VMNPACAP connections with the caudal POA neurons impact adipose tissue function and are important for induction of tissue thermogenesis. Our data suggests that the VMNPACAP → caudal POA neurocircuit and its components are critical for controlling energy balance by activating energy expenditure and body weight control.

The CTLH Ubiquitin Ligase Substrates ZMYND19 and MKLN1 Negatively Regulate mTORC1 at the Lysosomal Membrane

Most Epstein-Barr virus-associated gastric carcinoma (EBVaGC) harbor non-silent mutations that activate phosphoinositide 3 kinase (PI3K) to drive downstream metabolic signaling. To gain insights into PI3K/mTOR pathway dysregulation in this context, we performed a human genome-wide CRISPR/Cas9 screen for hits that synergistically blocked EBVaGC proliferation together with the PI3K antagonist alpelisib. Multiple subunits of carboxy terminal to LisH (CTLH) E3 ligase, including the catalytic MAEA subunit, were among top screen hits. CTLH negatively regulates gluconeogenesis in yeast, but not in higher organisms. Instead, we identified that the CTLH substrates MKLN1 and ZMYND19, which highly accumulated upon MAEA knockout, associated with one another and with lysosomes to inhibit mTORC1. ZMYND19/MKLN1 bound Raptor and RagA/C, but rather than perturbing mTORC1 lysosomal recruitment, instead blocked a late stage of its activation, independently of the tuberous sclerosis complex. Thus, CTLH enables cells to rapidly tune mTORC1 activity at the lysosomal membrane via the ubiquitin/proteasome pathway.

The E3 ubiquitin ligase RNF135 modulates chemotherapy resistance to oxaliplatin for colorectal cancer by modulating autophagy

BACKGROUND

RING finger protein 135 plays an important role in tumorigenesis and is associated with drug resistance.

METHODS

Bioinformatics analysis showed that RNF135 was significantly differentially expressed in colorectal cancer. RT-qPCR and western blot were used to detect the expression of RNF135. Immunohistochemical analysis were used to measure the expression of RNF135 and Ki-67.

RESULTS

The expression of RNF135 was up-regulated in human tissue samples and colorectal cancer and was positively correlated with Ki-67. Compared with oxaliplatin sensitive patients, RNF135 expression levels were higher in the tissue of resistant patients. The regulatory effect of RNF135 on colorectal cancer cells was further investigated in vitro. Therefore, inhibition of autophagy by down-regulating RNF135 can partially increase its susceptibility to oxaliplatin.

Multisite phosphorylation dictates selective E2-E3 pairing as revealed by Ubc8/UBE2H-GID/CTLH assemblies

Ubiquitylation is catalyzed by coordinated actions of E3 and E2 enzymes. Molecular principles governing many important E3-E2 partnerships remain unknown, including those for RING-family GID/CTLH E3 ubiquitin ligases and their dedicated E2, Ubc8/UBE2H (yeast/human nomenclature). GID/CTLH-Ubc8/UBE2H-mediated ubiquitylation regulates biological processes ranging from yeast metabolic signaling to human development. Here, cryoelectron microscopy (cryo-EM), biochemistry, and cell biology reveal this exquisitely specific E3-E2 pairing through an unconventional catalytic assembly and auxiliary interactions 70-100 Å away, mediated by E2 multisite phosphorylation. Rather than dynamic polyelectrostatic interactions reported for other ubiquitylation complexes, multiple Ubc8/UBE2H phosphorylation sites within acidic CK2-targeted sequences specifically anchor the E2 C termini to E3 basic patches. Positions of phospho-dependent interactions relative to the catalytic domains correlate across evolution. Overall, our data show that phosphorylation-dependent multivalency establishes a specific E3-E2 partnership, is antagonistic with dephosphorylation, rigidifies the catalytic centers within a flexing GID E3-substrate assembly, and facilitates substrate collision with ubiquitylation active sites.

The role of m6A mRNA modification in normal and malignant hematopoiesis

Hematopoiesis is a highly orchestrated biological process sustaining the supply of leukocytes involved in the maintenance of immunity, O2 and CO2 exchange, and wound healing throughout the lifetime of an animal, including humans. During early hematopoietic cell development, several waves of hematopoiesis require the precise regulation of hematopoietic ontogeny as well as the maintenance of hematopoietic stem and progenitor cells in the hematopoietic tissues, such as the fetal liver and bone marrow. Recently, emerging evidence has suggested the critical role of m6A messenger RNA (mRNA) modification, an epigenetic modification dynamically regulated by its effector proteins, in the generation and maintenance of hematopoietic cells during embryogenesis. In the adulthood, m6A has also been demonstrated to be involved in the functional maintenance of hematopoietic stem and progenitor cells in the bone marrow and umbilical cord blood, as well as the progression of malignant hematopoiesis. In this review, we focus on recent progress in identifying the biological functions of m6A mRNA modification, its regulators, and downstream gene targets during normal and pathological hematopoiesis. We propose that targeting m6A mRNA modification could offer novel insights into therapeutic development against abnormal and malignant hematopoietic cell development in the future.

LAD1 promotes malignant progression by diminishing ubiquitin-dependent degradation of vimentin in gastric cancer

BACKGROUND

Ladinin-1 (LAD1), an anchoring filament protein, has been associated with several cancer types, including cancers of the colon, lungs, and breast. However, it is still unclear how and why LAD1 causes gastric cancer (GC).

METHODS

Multiple in vitro and in vivo, functional gains and loss experiments were carried out in the current study to confirm the function of LAD1. Mass spectrometry was used to find the proteins that interact with LAD1. Immunoprecipitation analyses revealed the mechanism of LAD1 involved in promoting aggressiveness.

RESULTS

The results revealed that the LAD1 was overexpressed in GC tissues, and participants with increased LAD1 expression exhibited poorer disease-free survival (DFS) and overall survival (OS). Functionally, LAD1 promotes cellular invasion, migration, proliferation, and chemoresistance in vivo and in vitro in the subcutaneous patient-and cell-derived xenograft (PDX and CDX) tumor models. Mechanistically, LAD1 competitively bound to Vimentin, preventing it from interacting with the E3 ubiquitin ligase macrophage erythroblast attacher (MAEA), which led to a reduction in K48-linked ubiquitination of Vimentin and an increase in Vimentin protein levels in GC cells.

CONCLUSIONS

In conclusion, the current investigation indicated that LAD1 has been predicted as a possible prognostic biomarker and therapeutic target for GC due to its ability to suppress Vimentin-MAEA interaction.

Identifying E3 Ligase Substrates With Quantitative Degradation Proteomics

Controlled protein degradation by the ubiquitin-proteasome pathway is critical for almost all cellular processes. E3 ubiquitin ligases are responsible for targeting proteins for ubiquitylation and subsequent proteasomal degradation with spatial and temporal precision. While studies have revealed various E3-substrate pairs involved in distinct biological processes, the complete substrate profiles of individual E3 ligases are largely unknown. Here we report a new approach to identify substrates of an E3 ligase for proteasomal degradation using unnatural amino acid incorporation pulse-chase proteomics (degradomics). Applying this approach, we determine the steady-state substrates of the C-terminal to LisH (CTLH) E3 ligase, a multi-component complex with poorly defined substrates. By comparing the proteome degradation profiles of active and inactive CTLH-expressing cells, we successfully identify previously known and new potential substrates of CTLH ligase. Altogether, degradomics can comprehensively identify degradation substrates of an E3 ligase, which can be adapted for other E3 ligases in various cellular contexts.

Evaluation of obstructive sleep apnea: an analysis based on aberrant genes

BACKGROUND

Obstructive sleep apnea (OSA) is an upstream disorder that frequently causes multisystem disorders. Much research has revealed the pathogenesis of OSA, but there is still a lack of research on the complications caused by OSA.

METHODS

The mRNA expression and methylation dataset based on peripheral blood mononuclear cells (PBMCs) were downloaded from the Gene Expression Omnibus (GEO) database. All differential expressed genes (DEGs) were ranked using the Robust Rank Aggregation (RRA) algorithm. A weighted gene co-expression network analysis (WGCNA) was constructed. Subsequently, we used immune infiltration, enrichment analysis, and least absolute shrinkage and selection operator (LASSO) regression analysis for apnea and hypopnea index (AHI) and hypertension and excessive daytime sleepiness (EDS) and constructed diagnostic model using random forest algorithm.

RESULTS

In the present study, we identified 318 DEGs in PBMCs involved in pathogenesis or continuous positive airway pressure (CPAP) therapy. Pathway enrichment identified DEGs associated with protein regulation and metabolism. Notably, through intra group analysis, we found that the immune disorder was more significant for OSA in males, non-daytime sleepy, or non-hypertensive OSA. The area under the ROC curve of model for EDS prediction is 0.889 and 0.852 for hypertension. Notably, we found that the diagnostic model had a high linear predictive value for AHI.

CONCLUSIONS

Our results indicate that PBMCs are a significant component of alterations in OSA and are expected to explain the mechanism of multisystem diseases caused by OSA. The present study provides new insights for symptom evaluation, classification and treatment of OSA from the molecular level.

Genome-wide CRISPR-Cas9 screen analyzed by SLIDER identifies network of repressor complexes that regulate TRIM24

TRIM24 is an oncogenic chromatin reader that is frequently overexpressed in human tumors and associated with poor prognosis. However, TRIM24 is rarely mutated, duplicated, or rearranged in cancer. This raises questions about how TRIM24 is regulated and what changes in its regulation are responsible for its overexpression. Here, we perform a genome-wide CRISPR-Cas9 screen by fluorescence-activated cell sorting (FACS) that nominated 220 negative regulators and elucidated a regulatory network that includes the KAP1 corepressor, CNOT deadenylase, and GID/CTLH E3 ligase. Knocking out required components of these three complexes caused TRIM24 overexpression, confirming their negative regulation of TRIM24. Our findings identify regulators of TRIM24 that nominate previously unexplored contexts for this oncoprotein in biology and disease. These findings were enabled by SLIDER, a new scoring system designed and vetted in our study as a broadly applicable tool for analysis of CRISPR screens performed by FACS.

Advances in Understanding the Links between Metabolism and Autophagy in Acute Myeloid Leukemia: From Biology to Therapeutic Targeting

Autophagy is a highly conserved cellular degradation process that regulates cellular metabolism and homeostasis under normal and pathophysiological conditions. Autophagy and metabolism are linked in the hematopoietic system, playing a fundamental role in the self-renewal, survival, and differentiation of hematopoietic stem and progenitor cells, and in cell death, particularly affecting the cellular fate of the hematopoietic stem cell pool. In leukemia, autophagy sustains leukemic cell growth, contributes to survival of leukemic stem cells and chemotherapy resistance. The high frequency of disease relapse caused by relapse-initiating leukemic cells resistant to therapy occurs in acute myeloid leukemia (AML), and depends on the AML subtypes and treatments used. Targeting autophagy may represent a promising strategy to overcome therapeutic resistance in AML, for which prognosis remains poor. In this review, we illustrate the role of autophagy and the impact of its deregulation on the metabolism of normal and leukemic hematopoietic cells. We report updates on the contribution of autophagy to AML development and relapse, and the latest evidence indicating autophagy-related genes as potential prognostic predictors and drivers of AML. We review the recent advances in autophagy manipulation, combined with various anti-leukemia therapies, for an effective autophagy-targeted therapy for AML.

Regulation of adult stem cell quiescence and its functions in the maintenance of tissue integrity

Adult stem cells are important for mammalian tissues, where they act as a cell reserve that supports normal tissue turnover and can mount a regenerative response following acute injuries. Quiescent stem cells are well established in certain tissues, such as skeletal muscle, brain, and bone marrow. The quiescent state is actively controlled and is essential for long-term maintenance of stem cell pools. In this Review, we discuss the importance of maintaining a functional pool of quiescent adult stem cells, including haematopoietic stem cells, skeletal muscle stem cells, neural stem cells, hair follicle stem cells, and mesenchymal stem cells such as fibro-adipogenic progenitors, to ensure tissue maintenance and repair. We discuss the molecular mechanisms that regulate the entry into, maintenance of, and exit from the quiescent state in mice. Recent studies revealed that quiescent stem cells have a discordance between RNA and protein levels, indicating the importance of post-transcriptional mechanisms, such as alternative polyadenylation, alternative splicing, and translation repression, in the control of stem cell quiescence. Understanding how these mechanisms guide stem cell function during homeostasis and regeneration has important implications for regenerative medicine.

E3 ubiquitin ligase on the biological properties of hematopoietic stem cell

Hematopoietic stem cells are a group of heterogeneity cells with the potential to differentiate into various types of mature blood cells. Their basic biological properties include quiescence, self-renewal, multilineage differentiation, and homing ability, with the homing of exogenous hematopoietic stem cells after transplantation becoming a new focus, while the first three properties share some similarity in mechanism due to connectivity. In various complex mechanisms, the role of E3 ubiquitin ligases in hematopoietic homeostasis and malignant transformation is receiving increasing attention. As a unique part, E3 ubiquitin ligases play an important role in physiological regulation mechanism of posttranslational modification. In this review, we focus on the recent progress of the crucial role of E3 ubiquitin ligases that target specific proteins for ubiquitination to regulate biological properties of hematopoietic stem cells. Additionally, this paper deals with E3 ubiquitin ligases that affect the biological properties through aging and summarizes the relevant applications of targeting E3 ligases in hematopoietic malignancies. We present some ideas on the clinical application of E3 ubiquitin ligase to regulate hematopoietic stem cells and also believe that it is meaningful to study the upstream signal of these E3 ubiquitin ligases because hematopoietic stem cell dysfunction is caused by deficiency of some E3 ligases.

E3 ligase MAEA-mediated ubiquitination and degradation of PHD3 promotes glioblastoma progression

Glioblastoma (GBM) is the most common malignant glioma, with a high recurrence rate and a poor prognosis. However, the molecular mechanism behind the malignant progression of GBM is still unclear. In the present study, through the tandem mass tag (TMT)-based quantitative proteomic analysis of clinical primary and recurrent glioma samples, we identified that aberrant E3 ligase MAEA was expressed in recurrent samples. The results of bioinformatics analysis showed that the high expression of MAEA was related to the recurrence and poor prognosis of glioma and GBM. Functional studies showed that MAEA could promote proliferation, invasion, stemness and temozolomide (TMZ) resistance. Mechanistically, the data indicated that MAEA targeted prolyl hydroxylase domain 3 (PHD3) K159 to promote its K48-linked polyubiquitination and degradation, thus enhancing the stability of HIF-1α, thereby promoting the stemness and TMZ resistance of GBM cells through upregulating CD133. The in vivo experiments further confirmed that knocking down MAEA could inhibit the growth of GBM xenograft tumors. In summary, MAEA enhances the expression of HIF-1α/CD133 through the degradation of PHD3 and promotes the malignant progression of GBM.

RanBP9 controls the oligomeric state of CTLH complex assemblies

The CTLH (C-terminal to lissencephaly-1 homology motif) complex is a multisubunit RING E3 ligase with poorly defined substrate specificity and flexible subunit composition. Two key subunits, muskelin and Wdr26, specify two alternative CTLH complexes that differ in quaternary structure, thereby allowing the E3 ligase to presumably target different substrates. With the aid of different biophysical and biochemical techniques, we characterized CTLH complex assembly pathways, focusing not only on Wdr26 and muskelin but also on RanBP9, Twa1, and Armc8β subunits, which are critical to establish the scaffold of this E3 ligase. We demonstrate that the ability of muskelin to tetramerize and the assembly of Wdr26 into dimers define mutually exclusive oligomerization modules that compete with nanomolar affinity for RanBP9 binding. The remaining scaffolding subunits, Armc8β and Twa1, strongly interact with each other and with RanBP9, again with nanomolar affinity. Our data demonstrate that RanBP9 organizes subunit assembly and prevents higher order oligomerization of dimeric Wdr26 and the Armc8β-Twa1 heterodimer through its tight binding. Combined, our studies define alternative assembly pathways of the CTLH complex and elucidate the role of RanBP9 in governing differential oligomeric assemblies, thereby advancing our mechanistic understanding of CTLH complex architectures.

Effect of regulatory cell death on the occurrence and development of head and neck squamous cell carcinoma

Head and neck cancer is a malignant tumour with a high mortality rate characterized by late diagnosis, high recurrence and metastasis rates, and poor prognosis. Head and neck squamous cell carcinoma (HNSCC) is the most common type of head and neck cancer. Various factors are involved in the occurrence and development of HNSCC, including external inflammatory stimuli and oncogenic viral infections. In recent years, studies on the regulation of cell death have provided new insights into the biology and therapeutic response of HNSCC, such as apoptosis, necroptosis, pyroptosis, autophagy, ferroptosis, and recently the newly discovered cuproptosis. We explored how various cell deaths act as a unique defence mechanism against cancer emergence and how they can be exploited to inhibit tumorigenesis and progression, thus introducing regulatory cell death (RCD) as a novel strategy for tumour therapy. In contrast to accidental cell death, RCD is controlled by specific signal transduction pathways, including TP53 signalling, KRAS signalling, NOTCH signalling, hypoxia signalling, and metabolic reprogramming. In this review, we describe the molecular mechanisms of nonapoptotic RCD and its relationship to HNSCC and discuss the crosstalk between relevant signalling pathways in HNSCC cells. We also highlight novel approaches to tumour elimination through RCD.

Ageing and rejuvenation of tissue stem cells and their niches

Most adult organs contain regenerative stem cells, often organized in specific niches. Stem cell function is critical for tissue homeostasis and repair upon injury, and it is dependent on interactions with the niche. During ageing, stem cells decline in their regenerative potential and ability to give rise to differentiated cells in the tissue, which is associated with a deterioration of tissue integrity and health. Ageing-associated changes in regenerative tissue regions include defects in maintenance of stem cell quiescence, differentiation ability and bias, clonal expansion and infiltration of immune cells in the niche. In this Review, we discuss cellular and molecular mechanisms underlying ageing in the regenerative regions of different tissues as well as potential rejuvenation strategies. We focus primarily on brain, muscle and blood tissues, but also provide examples from other tissues, such as skin and intestine. We describe the complex interactions between different cell types, non-cell-autonomous mechanisms between ageing niches and stem cells, and the influence of systemic factors. We also compare different interventions for the rejuvenation of old regenerative regions. Future outlooks in the field of stem cell ageing are discussed, including strategies to counter ageing and age-dependent disease.

Modular UBE2H-CTLH E2-E3 complexes regulate erythroid maturation

The development of haematopoietic stem cells into mature erythrocytes - erythropoiesis - is a controlled process characterized by cellular reorganization and drastic reshaping of the proteome landscape. Failure of ordered erythropoiesis is associated with anaemias and haematological malignancies. Although the ubiquitin system is a known crucial post-translational regulator in erythropoiesis, how the erythrocyte is reshaped by the ubiquitin system is poorly understood. By measuring the proteomic landscape of in vitro human erythropoiesis models, we found dynamic differential expression of subunits of the CTLH E3 ubiquitin ligase complex that formed maturation stage-dependent assemblies of topologically homologous RANBP9- and RANBP10-CTLH complexes. Moreover, protein abundance of CTLH's cognate E2 ubiquitin conjugating enzyme UBE2H increased during terminal differentiation, and UBE2H expression depended on catalytically active CTLH E3 complexes. CRISPR-Cas9-mediated inactivation of CTLH E3 assemblies or UBE2H in erythroid progenitors revealed defects, including spontaneous and accelerated erythroid maturation as well as inefficient enucleation. Thus, we propose that dynamic maturation stage-specific changes of UBE2H-CTLH E2-E3 modules control the orderly progression of human erythropoiesis.

Discovery of Schistosoma mekongi circulating proteins and antigens in infected mouse sera

Schistosomiasis is a neglected tropical disease caused by an infection of the parasitic flatworms schistosomes. Schistosoma mekongi is a restricted Schistosoma species found near the Mekong River, mainly in southern Laos and northern Cambodia. Because there is no vaccine or effective early diagnosis available for S. mekongi, additional biomarkers are required. In this study, serum biomarkers associated with S. mekongi-infected mice were identified at 14-, 28-, 42-, and 56-days post-infection. Circulating proteins and antigens of S. mekongi in mouse sera were analyzed using mass spectrometry-based proteomics. Serine protease inhibitors and macrophage erythroblast attacher were down-regulated in mouse sera at all infection timepoints. In addition, 54 circulating proteins and 55 antigens of S. mekongi were identified. Notable circulating proteins included kyphoscoliosis peptidase and putative tuberin, and antigens were detected at all four infection timepoints, particularly in the early stages (12 days). The putative tuberin sequence of S. mekongi was highly similar to homologs found in other members of the genus Schistosoma and less similar to human and murine sequences. Our study provided the identity of promising diagnostic biomarkers that could be applicable in early schistosomiasis diagnosis and vaccine development.

Cryo-EM structures of Gid12-bound GID E3 reveal steric blockade as a mechanism inhibiting substrate ubiquitylation

Protein degradation, a major eukaryotic response to cellular signals, is subject to numerous layers of regulation. In yeast, the evolutionarily conserved GID E3 ligase mediates glucose-induced degradation of fructose-1,6-bisphosphatase (Fbp1), malate dehydrogenase (Mdh2), and other gluconeogenic enzymes. "GID" is a collection of E3 ligase complexes; a core scaffold, RING-type catalytic core, and a supramolecular assembly module together with interchangeable substrate receptors select targets for ubiquitylation. However, knowledge of additional cellular factors directly regulating GID-type E3s remains rudimentary. Here, we structurally and biochemically characterize Gid12 as a modulator of the GID E3 ligase complex. Our collection of cryo-EM reconstructions shows that Gid12 forms an extensive interface sealing the substrate receptor Gid4 onto the scaffold, and remodeling the degron binding site. Gid12 also sterically blocks a recruited Fbp1 or Mdh2 from the ubiquitylation active sites. Our analysis of the role of Gid12 establishes principles that may more generally underlie E3 ligase regulation.

Evolution of severe (transfusion-dependent) anaemia in myelodysplastic syndromes with 5q deletion is characterized by a macrophage-associated failure of the eythropoietic niche

Evolution of erythrocyte transfusion-dependent (RBC-TD) anaemia associated with haploinsufficiency of the ribosomal protein subunit S14 gene (RPS14) is a characteristic complication of myelodysplastic syndromes (MDS) with del(5q) [MDS.del(5q)]. Evaluating 39 patients with MDS.del(5q), <5% of anaemia progression was attributable to RPS14-dependent alterations of normoblasts, pro-erythroblasts, or CD34⁺ CD71⁺ precursors. Ninety-three percent of anaemia progression and 70% of the absolute decline in peripheral blood Hb value were attributable to disappearance of erythroblastic islands (Ery-Is). Ery-Is loss occurred independently of blast excess, TP53 mutation, additional chromosome aberrations and RPS14-dependent alterations of normoblasts and pro-erythroblasts. It was associated with RPS14-dependent intrinsic (S100A8⁺ ) and extrinsic [tumour necrosis factor α (TNF-α)-overproduction] alterations of (CD169⁺ ) marrow macrophages (p < 0.00005). In a mouse model of RPS14 haploinsufficiency, Ery-Is disappeared to a similar degree: approximately 70% of Ery-Is loss was related to RPS14-dependent S100A8 overexpression of marrow macrophages, less than 20% to that of CD71^high Ter119^- immature precursors, and less than 5% to S100A8/p53 overexpression of normoblasts or pro-erythroblasts. Marked Ery-Is loss predicted reduced efficacy (erythrocyte transfusion independence) of lenalidomide therapy (p = 0.0006). Thus, erythroid hypoplasia, a characteristic complication of MDS.del(5q), seems to result primarily from a macrophage-associated failure of the erythropoietic niche markedly reducing the productive capacity of erythropoiesis as the leading factor in anaemia progression and evolution of RBC-TD in MDS.del(5q).

Lysosomes in Stem Cell Quiescence: A Potential Therapeutic Target in Acute Myeloid Leukemia

Lysosomes are cellular organelles that regulate essential biological processes such as cellular homeostasis, development, and aging. They are primarily connected to the degradation/recycling of cellular macromolecules and participate in cellular trafficking, nutritional signaling, energy metabolism, and immune regulation. Therefore, lysosomes connect cellular metabolism and signaling pathways. Lysosome's involvement in the critical biological processes has rekindled clinical interest towards this organelle for treating various diseases, including cancer. Recent research advancements have demonstrated that lysosomes also regulate the maintenance and hemostasis of hematopoietic stem cells (HSCs), which play a critical role in the progression of acute myeloid leukemia (AML) and other types of cancer. Lysosomes regulate both HSCs' metabolic networks and identity transition. AML is a lethal type of blood cancer with a poor prognosis that is particularly associated with aging. Although the genetic landscape of AML has been extensively described, only a few targeted therapies have been produced, warranting the need for further research. This review summarizes the functions and importance of targeting lysosomes in AML, while highlighting the significance of lysosomes in HSCs maintenance.

Identification of Regulatory Factors and Prognostic Markers in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive degeneration of motor neurons, leading to muscle atrophy, paralysis and even death. Immune disorder, redox imbalance, autophagy disorder, and iron homeostasis disorder have been shown to play critical roles in the pathogenesis of ALS. However, the exact pathogenic genes and the underlying mechanism of ALS remain unclear. The purpose of this study was to screen for pathogenic regulatory genes and prognostic markers in ALS using bioinformatics methods. We used Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, gene set enrichment analysis (GSEA), and expression regulation network analysis to investigate the function of differentially expressed genes in the nerve tissue, lymphoid tissue, and whole blood of patients with ALS. Our results showed that the up-regulated genes were mainly involved in immune regulation and inflammation, and the down-regulated genes were mainly involved in energy metabolism and redox processes. Eleven up-regulated transcription factors (CEBPB, CEBPD, STAT5A, STAT6, RUNX1, REL, SMAD3, GABPB2, FOXO1, PAX6, and FOXJ1) and one down-regulated transcription factor (NOG) in the nerve tissue of patients with ALS likely play important regulatory roles in the pathogenesis of ALS. Based on construction and evaluation of the ALS biomarker screening model, cluster analysis of the identified characteristic genes, univariate Cox proportional hazards regression analysis, and the random survival forest algorithm, we found that MAEA, TPST1, IFNGR2, and ALAS2 may be prognostic markers regarding the survival of ALS patients. High expression of MAEA, TPST1, and IFNGR2 and low expression of ALAS2 in ALS patients may be closely related to short survival of ALS patients. Taken together, our results indicate that immune disorders, inflammation, energy metabolism, and redox imbalance may be the important pathogenic factors of ALS. CEBPB, CEBPD, STAT5A, STAT6, RUNX1, REL, SMAD3, GABPB2, FOXO1, PAX6, FOXJ1, and NOG may be important regulatory factors linked to the pathogenesis of ALS. MAEA, TPST1, IFNGR2, and ALAS2 are potential important ALS prognostic markers. Our findings provide evidence on the pathogenesis of ALS, potential targets for the development of new drugs for ALS, and important markers for predicting ALS prognosis.