Impaired Differentiation Research Articles

KAT6B is required for histone 3 lysine 9 acetylation and SOX gene expression in the developing brain.

Heterozygous mutations in the histone lysine acetyltransferase gene KAT6B (MYST4/MORF/QKF) underlie neurodevelopmental disorders, but the mechanistic roles of KAT6B remain poorly understood. Here, we show that loss of KAT6B in embryonic neural stem and progenitor cells (NSPCs) impaired cell proliferation, neuronal differentiation, and neurite outgrowth. Mechanistically, loss of KAT6B resulted in reduced acetylation at histone H3 lysine 9 and reduced expression of key nervous system development genes in NSPCs and the developing cortex, including the SOX gene family, in particular Sox2, which is a key driver of neural progenitor proliferation, multipotency and brain development. In the fetal cortex, KAT6B occupied the Sox2 locus. Loss of KAT6B caused a reduction in Sox2 promoter activity in NSPCs. Sox2 overexpression partially rescued the proliferative defect of Kat6b -/- NSPCs. Collectively, these results elucidate molecular requirements for KAT6B in brain development and identify key KAT6B targets in neural precursor cells and the developing brain.

Abstract 4137935: Adipogenesis in Bone Marrow Niche under Cardiac Stress Worsens Cardiac Function

Background: We have recently reported that repetitive cardiac decompensation with multimorbidity often experienced by patients with heart failure (HF) is attributed to epigenetic modifications of hematopoietic stem cells (HSCs) in the bone marrow (BM). HF reprogrammed HSCs differentiation and altered tissue macrophage homeostasis. These findings demonstrate that the BM can carry an innate immune memory of cardiac stress that may exacerbate HF and predispose other organs to pathology. Aims: Because the stemness of HSCs is mainly regulated by mesenchymal stromal cells (MSCs) in the BM niche, we investigated phenotypic alterations of MSCs under cardiac stress. Methods&Results: Transcriptome analysis of MSCs showed preferential differentiation toward adipocytes in murine pressure overload models. In vitro assays and histological BM sections also support this finding. Furthermore, single-cell RNA sequencing of MSCs demonstrated that the percentage of adipocyte-primed MSCs increased in proportion to the severity of cardiac dysfunction, and also correlated with the frequency of myeloid-lineage progenitor cells. To investigate the influence of adipo-lineage MSCs on HSCs, we conducted BM transplantation supplemented with MSCs from control or HF mice. Recipient mice transplanted with HF-MSCs showed significant increases in myeloid-biased multipotent progenitors in BM and myeloid cells in peripheral blood. Additionally, the number of proinflammatory cardiac macrophages was significantly increased in the HF-MSCs group, promoting cardiac fibrosis and dysfunction. Conclusions: Our results demonstrated that the BM niche could perceive cardiac stress in the form of adipocytic skewing of MSCs in the setting of HF, which changed the differentiation behavior in HSCs and ultimately led to further deterioration of cardiac function through the impaired differentiation of circulating monocytes into cardiac macrophages. Therefore, suppressing the adipocytic differentiation of MSCs could have a novel therapeutic potential to avoid repeated HF events.

EPCO-20. MUTANT IDH INHIBITORS INDUCE LINEAGE DIFFERENTIATION IN IDH-MUTANT OLIGODENDROGLIOMA

Abstract IDH-mutant gliomas exhibit variable responses to mutant-IDH inhibitor (IDHi) therapy; yet, the molecular mechanisms underlying these responses remain poorly understood. Here, we investigate the cellular underpinnings of response by leveraging single cell/nuclei RNA-sequencing of on-treatment IDH-mutant oligodendroglioma tumor samples resected from three patients who benefited clinically from treatment. We integrate these findings with single cell and bulk RNA-seq data from independent cohorts and experimental models. We find that IDHi treatment promotes robust differentiation towards the astrocytic lineage, accompanied by stem-like cell depletion and reduced proliferation. Notably, NOTCH1 mutations are associated with impaired astrocytic differentiation, potentially negatively impacting response to IDHi. This study unveils the differentiating effects of IDHi on oligodendroglioma cellular hierarchies and identifies a potential genetic marker for optimizing patient selection. Paper was recently published in Cancer Cell (10.1016/j.ccell.2024.03.008).

THE ROLE OF INTRACELLULAR SIGNALING PATHWAYS IN THE DEVELOPMENT OF TROPHIC PATHOLOGIES OF THE LOWER EXTREMITIES AND THEIR REGENERATION UNDER TYPE 2 DIABETES (PART 1)

Introduction. This review article addresses the critical issue of the development and regeneration of chronic trophic ulcers in the context of type 2 diabetes. This pathological process is associated with inhibited cell proliferation, impaired differentiation of various cell types, and disrupted mechanisms that regulate cell death. An analysis of recent scientific literature also highlights the involvement of key intracellular signaling pathways in the development of chronic ulcerative pathologies of the lower extremities, as observed in both experimental animal models and patients with type II diabetes. Despite advancements, this issue remains insufficiently explored in both theory and practice, underscoring its ongoing relevance. The aim of this study is to identify the roles of key signaling pathways—transforming growth factor β (TGF-β), phosphatidylinositol 3-kinase/serine-threonine kinase (PI3K/Akt), and Wnt/β-catenin—in the inflammatory response, regenerative mechanisms, and healing processes of soft tissue damage and trophic ulcers in experimental animals and patients with type II diabetes. Materials and Methods. This study is based on an analysis of current scientific literature that addresses this topic. Results. It has been found out that changes in the content and activity of key molecules of signaling pathways lead to disruption of carbohydrate homeostasis and the occurrence of structural and functional dysfunction in damaged tissues against the background of type II diabetes. These include TGF-β, PI3K, Akt and β-catenin. Analysis of experimental data demonstrated that both under the conditions of type II diabetes development and in the occurrence of chronic ulcers of the lower extremities, against the background of this endocrine disease, there is an increase in the level of TGF-β. At the same time the activity of the PI3K/Akt signaling pathway in the above-mentioned studied groups was reduced. The relationship between the development of type II diabetes and the Wnt/β-catenin signaling pathway has been established. Suppression of its activity was accompanied by impaired regeneration of chronic trophic ulcers in type II diabetes. Conclusion. Thus, the mechanism of type II diabetes and chronic peptic ulcer disease, in the same pathology, is associated with a impaired activity of signaling cascades. This concerns the following cellular systems such as TGF-β, PI3K/Akt and Wnt/β-catenin. They can be considered as potential therapeutic targets for the development of newest methods for the treatment of chronic trophic ulcers in type II diabetes in order to accelerate the recovery process of volumetric tissue damage of the lower extremities.

EPCO-21. ELUCIDATING THE FUNCTIONAL RELEVANCE OF ATRX-DEFICIENCY IN H3.3-G34-MUTANT DIFFUSE HEMISPHERIC GLIOMA

Abstract Diffuse hemispheric gliomas (DHGs) account for 30% of aggressive cerebral tumors in children and young adults, exhibiting abysmal outcomes. Co-existing recurrent mutations in H3.3 histones at residue G34 (H3.3-G34R/V mutation) and concurrent inactivating mutations in TP53 and α-thalassemia/intellectual disability-X-linked gene (ATRX) implicate a coordinated molecular effort to drive oncogenesis. ATRX, a core component of the SWItch/Sucrose Non-Fermentable chromatin remodeling complex, regulates the incorporation of histone H3.3 into chromatin sites across the genome to maintain epigenome integrity. Yet, it is unclear how ATRX loss combines with H3.3-G34R/V mutations to influence cellular phenotype and dysregulate neuro-developmental programs. We propose that ATRX deficiency coordinates with key oncogenic partners by inducing oncogenic transcriptional programs and neuro-developmental pathways in DHGs. To investigate this, we employed CRISPR-editing to model H3.3-G34R followed by ATRX knockdown (ATRX-KD) in a TP53 mutant (TP53-mut) human-induced pluripotent stem cell (h-iPSC) line, developing an isogenic system to map contributions to epigenetic dysfunction made by specific molecular alterations. Upon differentiation of our h-iPSCs to neural stem cells (NSCs), we found unique transcriptional profiles associated with each genetic alteration, with upregulation of forebrain progenitor genes driven by ATRX-loss. Hierarchal clustering of normalized transcript counts revealed gene signatures from each model driving unique functional pathways, with the ATRX-KD and the triple mutant (TP53-mut, ATRX-KD, H3.3-G34R) signatures enriched for neural development pathways. Additionally, both signatures were associated with published transcriptional profiles of G34-mutant DHGs, emphasizing the disease relevance of our models. Further, time-course analysis using cerebral organoids uncovered distinct morphological changes with each alteration, with the triple mutant exhibiting impaired differentiation at later time points. These latter findings suggest that ATRX deficiency transcriptionally influences early neuronal differentiation, effects further refined by H3.3-G34 mutation. To conclude, our innovative models demonstrate the involvement of ATRX in neuro-developmental and differentiation phenotypes, illuminating underlying molecular features of aggressive DHGs.

Dynamic mRNA Stability Buffer Transcriptional Activation During Neuronal Differentiation and Is Regulated by SAMD4A.

Neurons are exceptionally sensitive to oxidative stress, which is the basis for many neurodegenerative disease pathophysiologies. The posttranscriptional basis for neuronal differentiation and behavior is not well characterized. The steady-state levels of mRNA are outcomes of an interplay between RNA transcription and decay. However, the correlation between mRNA transcription, translation, and stability remains elusive. We utilized a SH-SY5Y-based neural differentiation model that is widely used to study neurodegenerative diseases. After neuronal differentiation, we observed enhanced sensitivity of mature neurons to mitochondrial stresses and ferroptosis induction. We employed a newly developed simplified mRNA stability profiling technique to explore the role of mRNA stability in SH-SY5Y neuronal differentiation model. Transcriptome-wide mRNA stability analysis revealed neural-specific RNA stability kinetics. Our analysis revealed that mRNA stability could either exert the buffering effect on gene products or change in the same direction as transcription. Importantly, we observed that changes in mRNA stability corrected over or under transcription of mRNAs to maintain mRNA translation dynamics. Furthermore, we conducted integrative analysis of our mRNA stability data set, and a published CRISPR-i screen focused on neuronal oxidative stress responses. Our analysis unveiled novel neuronal stress response genes that were not evident at the transcriptional or translational levels. SEPHS2 emerged as an important neuronal stress regulator based on this integrative analysis. Motif analysis unveiled SAMD4A as a major regulator of the dynamic changes in mRNA stability observed during differentiation. Knockdown of SAMD4A impaired neuronal differentiation and influenced the response to oxidative stress. Mechanistically, SAMD4A was found to alter the stability of several mRNAs. The novel insights into the interplay between mRNA stability and cellular behaviors provide a foundation for understanding neurodevelopmental processes and neurodegenerative disorders and highlight dynamic mRNA stability as an important layer of gene expression.

Dichloroacetate, a pyruvate dehydrogenase activator, alleviates high-fat-induced impairment of myogenic differentiation in skeletal muscles.

Obesity-induced impairment of myogenic differentiation leads to muscle loss and sarcopenia. Pyruvate dehydrogenase (PDH) plays a crucial role in glucose metabolism and is associated with muscle differentiation. However, the effect of dichloroacetate (DCA), a PDH activator, on obesity-induced impairment of myogenic differentiation remains unknown. Here, we evaluated the effects of DCA treatment on high-fat intake-induced impairment of myogenic differentiation in C2C12 cells and C57BL/6 mice. In C2C12 cells, DCA treatment improved PDH activity that was reduced by palmitate (PAL) and decreased the lactate concentrations in the media. Additionally, DCA reversed PAL- and high-fat diet (HFD)-induced decrease in the expression of myoblast determination protein 1 (MyoD), myogenin (MyoG) and myosin heavy chain (MyHC) in C2C12 cells and C57BL/6 mice. To explore the possible mechanism, DCA treatment restored the levels of p-Akt, p-FoxO1, p-FoxO3a and p-p38 MAPK levels in PAL-treated C2C12 cells. Moreover, the protective effects of DCA were reversed by treatment with the Akt inhibitor MK2206 in C2C12 cells. In summary, DCA treatment alleviated high-fat intake-induced impairment of myogenic differentiation via Akt signalling, suggesting its potential in treating obesity-associated muscle loss and sarcopenia.

BPDCN MYB fusions regulate cell cycle genes, impair differentiation and induce myeloid-dendritic cell leukemia.

MYB fusions are recurrently found in select cancers, including blastic plasmacytoid dendritic cell neoplasm (BPDCN), an acute leukemia with poor prognosis. They are markedly enriched in BPDCN compared to other blood cancers, and in some patients are the only obvious somatic mutation detected. This suggests they may alone be sufficient to drive dendritic cell transformation. MYB fusions are hypothesized to alter the normal transcription factor activity of MYB, but mechanistically how they promote leukemogenesis is poorly understood. Using CUT&RUN chromatin profiling, we found that in BPDCN leukemogenesis, MYB switches from being a regulator of dendritic cell lineage genes to aberrantly regulating G2/M cell cycle control genes. MYB fusions found in BPDCN patients increased the magnitude of DNA binding at these locations, and this was linked to BPDCN-associated gene expression changes. Furthermore, expression of MYB fusions in vivo impaired dendritic cell differentiation and induced transformation to generate a mouse model of myeloid-dendritic acute leukemia. Therapeutically, we present evidence that all-trans retinoic acid (ATRA) may cause loss of MYB protein and cell death in BPDCN.

Cardioimmunology in Health and Diseases: Impairment of the Cardio-Spleno-Bone Marrow Axis Following Myocardial Infarction in Diabetes Mellitus.

A comprehensive understanding of the cardio-spleen-bone marrow immune cell axis is essential for elucidating the alterations occurring during the pathogenesis of diabetes mellitus (DM). This study investigates the dynamics of immune cell kinetics in DM after myocardial infarction (MI) over time. MI was induced in diabetic and healthy control groups using C57BL/N6 mice, with sacrifices occurring at days 1, 3, 7, and 28 post-MI to collect heart, peripheral blood (PB), spleen, and bone marrow (BM) samples. Cell suspensions from each organ were isolated and analyzed via flow cytometry. Additionally, the endothelial progenitor cell-colony-forming assay (EPC-CFA) was performed using mononuclear cells derived from BM, PB, and the spleen. The results indicated that, despite normal production in BM and the spleen, CD45+ cells were lower in the PB of DM mice at days 1 to 3. Further analysis revealed a reduction in total and pro-inflammatory neutrophils (N1s) in PB at days 1 to 3 and in the spleen at days 3 to 7 in DM mice, suggesting that DM-induced alterations in splenic neutrophils fail to meet the demand in PB and ischemic tissues. Infiltrating macrophages (total, M1, M2) were reduced at day 3 in the DM-ischemic heart, with total and M1 (days 1-3) and M2 (days 3-7) macrophages being significantly decreased in DM-PB compared to controls, indicating impaired macrophage recruitment and polarization in DM. Myeloid dendritic cells (mDCs) in the heart were higher from days 1 to 7, which corresponded with the enhanced recruitment of CD8+ cells from days 1 to 28 in the DM-infarcted myocardium. Total CD4+ cells decreased in DM-PB at days 1 to 3, suggesting a delayed adaptive immune response to MI. B cells were reduced in PB at days 1 to 3, in myocardium at day 3, and in the spleen at day 7, indicating compromised mobilization from BM. EPC-CFA results showed a marked decrease in definitive EPC colonies in the spleen and BM from days 1 to 28 in DM mice compared to controls in vitro, highlighting that DM severely impairs EPC colony-forming activity by limiting the differentiation of EPCs from primitive to definitive forms. Taking together, this study underscores significant disruptions in the cardio-spleen-bone marrow immune cell axis following MI in DM, revealing delayed innate and adaptive immune responses along with impaired EPC differentiation.

Role of the PGAM5-CypD mitochondrial pathway in methylglyoxal-induced bone loss in diabetic osteoporosis

Diabetic osteoporosis (DOP) is a skeletal complication with a high rate of disability. It results in a great burden to the patient's family and society. Methylglyoxal (MG) is a toxic by-product of the glycolytic process that occurs during diabetic conditions. It causes osteoblastic injury and con-tributes to the initiation and development of DOP. Disruption of mitochondrial homeostasis has been implicated as a cause of dysregulated osteo-blastogenesis, an essential step in bone formation. It is unclear whether mitochondrial dysfunction is involved in MG-induced osteoblast dysfunction. In this study, we showed that mitochondrial dysfunction contributes to MG-induced MC3T3-E1 cell apoptosis and impaired differentiation. A significant reduction of mitochondrial membrane potential (MMP) and ATP production occurred in MG-induced osteoblasts as well as increasing mitochondrial reactive oxygen species (mtROS) and intracellular Ca2+. Classical antioxidant N-Acetylcysteine (NAC) significantly attenuated mitochondrial dysfunction as well as osteoblast apoptosis and osteogenic differentiation damage induced by MG. More importantly, we found that activating phosphoglycerate mutase family member 5 (PGAM5) and cyclophilin D (CypD), which contributes to mitochondrial homeostasis, is involved in MG-induced osteoblast injury. Both PGAM5 and CypD knockdown effectively reversed osteoblast viability and function, whereas PGAM5 or CypD overexpression aggravated osteoblast injury caused by MG. Moreover, the result of co-transfection revealed that PGAM5 is an upstream signaling molecule of CypD. By constructing type I diabetes mouse models, we further found that the expression of PGAM5 and CypD were both increased in the femur along with a reduction of ATP and increased TUNEL-positive cells. These results, for the first time, suggest that MG-induced mitochondrial dysfunction induces osteoblast injury through the PGAM5-CypD pathway. This study provides insight into the prevention and treatment of DOP. Lay summaryThis study highlights the role of mitochondria in regulating osteoblast viability and function under conditions of diabetic osteoporosis (DOP). We found that the PGAM5-CypD mitochondrial pathway is activated following glycolytic by-product methylglyoxal (MG) treatment, which contributes to mitochondrial dysfunction and osteogenic dysfunction. This mechanism implicates mitochondria as a potential therapeutic target for osteoporosis.

DPP an extracellular matrix molecule induces Wnt5a mediated signaling to promote the differentiation of adult stem cells into odontogenic lineage

Dentin phosphophoryn (DPP) an extracellular matrix protein activates Wnt signaling in DPSCs (dental pulp stem cells). Wnt/β catenin signaling is essential for tooth development but the role of DPP-mediated Wnt5a signaling in odontogenesis is not well understood. Wnt5a is typically considered as a non-canonical Wnt ligand that elicits intracellular signals through association with a specific cohort of receptors and co-receptors in a cell and context–dependent manner. In this study, DPP facilitated the interaction of Wnt5a with Frizzled 5 and LRP6 to induce nuclear translocation of β-catenin. β-catenin has several nuclear binding partners that promote the activation of Wnt target genes responsible for odontogenic differentiation. Interestingly, steady increase in the expression of Vangl2 receptor suggest planar cell polarity signaling during odontogenic differentiation. In vitro observations were further strengthened by the low expression levels of Wnt5a and β-catenin in the teeth of DSPP KO mice which exhibit impaired odontoblast differentiation and defective dentin mineralization. Together, this study suggests that the DPP-mediated Wnt5a signaling could be exploited as a therapeutic approach for the differentiation of dental pulp stem cells into functional odontoblasts and dentin regeneration.

Polydeoxyribonucleotide ameliorates IL-1β-induced impairment of chondrogenic differentiation in human bone marrow-derived mesenchymal stem cells

Osteoarthritis (OA) is a degenerative disease of the joints, prevalent worldwide. Polydeoxyribonucleotide (PDRN) is used for treating knee OA. However, the role of PDRN in IL-1β-induced inflammatory responses in human bone marrow-derived mesenchymal stem cells (hBMSCs) remains unknown. Here, we investigated the role of PDRN in IL-1β-induced impairment of chondrogenic differentiation in hBMSCs. hBMSCs treated with PDRN showed a large micromass, enhanced safranin O and alcian blue staining intensity, and increased expression of chondrogenic genes in IL-1β-induced inflammatory responses, in addition to regulation of catabolic and anabolic genes. In addition, PDRN treatment suppressed the expression of inflammatory cytokines and mitigated IL-1β-induced apoptosis in hBMSCs. Mechanistically, PDRN treatment increased the formation of cyclic adenosine monophosphate (cAMP) and upregulated the phosphorylation of cAMP-dependent protein kinase A (PKA)/cAMP response element binding protein (CREB) through the adenosine A2A receptor in hBMSCs and thus blocked the nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) signaling pathway. Thus, IL-1β-induced expression of inflammatory cytokines in hBMSCs was directly reduced by adenosine A2A receptor activation. Based on our results, we suggest that PDRN may be a promising MSC-based therapeutic agent for OA.

Expression of key molecules of the classical inflammation activation pathway in blood leukocytes of autistic children

Autism spectrum disorders (ASD) are complex neurodevelopmental disorders, whose causes are currently not fully understood. Research suggests that inflammation and changes in immune functions may play an important role in the development of autism. Increased levels of proinflammatory cytokines in the brains of autistic children lead to negative regulation of synaptic plasticity, as well as impaired proliferation and differentiation of neurons through activation of the nuclear factor kappa B (NF-κB) signaling pathway. The purpose of the work is to analyze the levels of mRNA: TLR2, TLR4, MyD88, IκBα, NF-κB p50, NF-κB p65 in peripheral blood leukocytes of children in comparison with the severity of autism spectrum disorders. The study included 126 children aged from 3 to 13 years (the ratio of boys to girls was 4:1): 45 children with typical neurodevelopment, and 81 children with a clinically confirmed diagnosis of autism. According to the Childhood Autism Rating Scale, 51 children had mild to moderate ASD (CARS score: 29-36), and 30 children had severe autism (CARS score: 36-60). The expression of inflammatory signal transduction pathway molecules was determined in peripheral blood leukocytes using real-time polymerase chain reaction with SYBRGreen. To compare the samples, one-way ANOVA and Tukey’s test were used. It was found that in leukocytes of children with severe ASD, the expression of the adapter protein MyD88 and the p65 subunit of the nuclear transcription factor NF-κB was significantly reduced, and the expression of the NF-κB inhibitor, IκBα, was significantly increased, compared to the control group. In leukocytes of children with mild ASD, a decrease in NF-κB p65 expression was found at a trend level. When comparing groups of children with different severity of autism symptoms (mild/severe), no significant differences were found in the levels of mRNA of key signaling molecules of the classical inflammation activation pathway in blood leukocytes. Thus, in the blood leukocytes of children with severe ASD, suppression of the expression of key molecules of the classical inflammation activation pathway (NF-κB) is observed, which leads to a decrease in the expression of pro-inflammatory cytokines: IL-1β, IL-18 and IL-2, against the background of increased expression of key cytokine of Th1 cells – IFNγ.

Dependence of PAX3-FOXO1 chromatin occupancy on ETS1 at important disease-promoting genes exposes new targetable vulnerability in Fusion-Positive Rhabdomyosarcoma

AbstractRhabdomyosarcoma (RMS), a malignancy of impaired myogenic differentiation, is the most common soft tissue pediatric cancer. PAX3-FOXO1 oncofusions drive the majority of the clinically more aggressive fusion-positive rhabdomyosarcoma (FP-RMS). Recent studies have established an epigenetic basis for PAX3-FOXO1-driven oncogenic processes. However, details of PAX3-FOXO1 epigenetic mechanisms, including interactions with, and dependence on, other chromatin and transcription factors, are incompletely understood. We previously identified a novel disease-promoting epigenetic axis in RMS, involving the histone demethylase KDM3A and the ETS1 transcription factor, and demonstrated that this epigenetic axis interfaces with PAX3-FOXO1 both phenotypically and transcriptomically, including co-regulation of biological processes and genes important to FP-RMS progression. In this study, we demonstrate that KDM3A and ETS1 colocalize with PAX3-FOXO1 to enhancers of important disease-promoting genes in FP-RMS, including FGF8, IL4R, and MEST, as well as PODXL, which we define herein as a new FP-RMS-promoting gene. We show that ETS1, which is induced by both PAX3-FOXO1 and KDM3A, exists in complex with PAX3-FOXO1, and augments PAX3-FOXO1 chromatin occupancy. We further show that the PAX3-FOXO1/ETS1 complex can be disrupted by the clinically relevant small molecule inhibitor YK-4-279. YK-4-279 displaces PAX3-FOXO1 from chromatin and interferes with PAX3-FOXO1-dependent gene regulation, resulting in potent inhibition of growth and invasive properties in FP-RMS, along with downregulation of FGF8, IL4R, MEST and PODXL expression. We additionally show that, in some FP-RMS, KDM3A also increases PAX3-FOXO1 levels. Together, our studies illuminate mechanisms of action of the KDM3A/ETS1 regulatory module, and reveal novel targetable mechanisms of PAX3-FOXO1 chromatin complex regulation, in FP-RMS.

Congenital enteropathies in children: An algorithm for differential diagnosis and therapeutic management. Case report

Infant diarrhea may be caused by infectious, allergic, or surgical diseases. A distinct group comprises congenital enteropathies, a heterogeneous group of genetically determined diseases, including defects in the absorption and transport of nutrients and electrolytes, impaired differentiation of enterocytes and enteroendocrine cells, and defects in the modulation of the intestinal immune response. The final diagnosis of enteropathies is based on the results of molecular genetic tests; however, a detailed assessment of clinical and medical history data and the results of laboratory and instrumental studies enables quick diagnostic search direction and choice of the correct therapeutic tactics. The article considers the algorithm for the differential diagnosis of congenital diarrhea, presents a clinical case of congenital osmotic diarrhea due to disaccharidase insufficiency, and considers the difficulties of the diagnostic search and approaches to diet therapy. The prospective of using a fructose-based formula, Galactomin-19, in the diet therapy of glucose-galactose malabsorption, is presented.

Intrinsic functional defects in B cells of patients with NFKB2 mutations.

Mutations in the human nuclear factor-κB2 gene (NFKB2) are associated with common variable immunodeficiency (CVID) or combined immunodeficiency diseases (CID), characterized by B-cell lymphopenia, hypogammaglobulinemia, and T cell dysfunction. This study investigated whether B cells with NFKB2 mutations exhibit intrinsic impairments in activation, class-switch recombination, and differentiation. We analyzed five patients from four unrelated families with CVID, each carrying a heterozygous NFKB2 mutation: P1 (C.2595_2614del, p.A867Gfs*12), P2 (C.2597G>A, p.S866N), P3 (C.2540dupT, p.R848Efs*38), and P4 and P5 (C.2570_2571insCAGCACA, p.A860Qfs*28). The patients with frameshift mutations (P1, P3, P4, and P5) exhibited truncated proteins detectable in their peripheral blood mononuclear cells, while P2 had a missense mutation. All identified mutations disrupted the processing of p100 into the active p52 form, resulting in NF-κB2 loss-of-function and IκBδ gain-of-function. Clinically, P1, P2, and P3 exhibited B-cell lymphopenia, and all five patients presented with hypogammaglobulinemia. Notably, P2 exhibited a markedly low B-cell count, associated with increased proportions of memory B and IgD-CD27- double negative B cells. In vitro experiments with naïve B cells from P1 and P4 demonstrated decreased survival, impaired activation, and reduced differentiation into CD27+IgD- cells and plasmablasts, while class switch recombination was unaffected. These findings reveal novel B cell-intrinsic functional defects in patients with NFKB2 mutations.

Dysregulation of epigenetic modifications in inborn errors of immunity.

Inborn errors of immunity (IEIs) are a group of typically monogenic disorders characterized by dysfunction in the immune system. Individuals with these disorders experience increased susceptibility to infections, autoimmunity and malignancies due to abnormal immune responses. Epigenetic modifications, including DNA methylation, histone modifications and chromatin remodeling, have been well explored in the regulation of immune cell development and effector function. Aberrant epigenetic modifications can disrupt gene expression profiles crucial for immune responses, resulting in impaired immune cell differentiation and function. Dysregulation of these processes caused by mutations in genes involving in epigenetic modifications has been associated with various IEIs. In this review article, we focus on IEIs that are caused by mutations in 13 genes involved in the regulation of DNA methylation, histone modification and chromatin remodeling.

Oscillatory DeltaC Expression in Neural Progenitors Primes the Prototype of Forebrain Development.

Notch signaling plays a pivotal role in regulating various developmental processes, particularly in controlling the timing of neuronal production within the developing neocortex. Central to this regulatory mechanism is the oscillatory pattern of Delta, which functions as a developmental clock modulator. Its deficiency profoundly impairs mammalian brain formation, highlighting its fundamental role in brain development. However, zebrafish carrying a mutation in the functional ortholog DeltaC (dlc) within their functional ortholog exhibit an intact forebrain structure, implying evolutionary variations in Notch signaling within the forebrain. In this study, we unveil the distinct yet analogous expression profiles of Delta and Her genes in the developing vertebrate forebrain. Specifically, for the first time, we detected the oscillatory expression of the Delta gene dlc in the developing zebrafish forebrain. Although this oscillatory pattern appeared irregular and was not pervasive among the progenitor population, attenuation of the dlc-involved Notch pathway using a γ-secretase inhibitor impaired neuronal differentiation in the developing zebrafish forebrain, revealing the indispensable role of the dlc-involved Notch pathway in regulating early zebrafish neurogenesis. Taken together, our results demonstrate the foundational prototype of dlc-involved Notch signaling in the developing zebrafish forebrains, upon which the intricate patterns of the mammalian neocortex may have been sculpted.

Sight of Aged Microplastics Adsorbing Heavy Metal Exacerbated Intestinal Injury: A Mechanistic Study of Autophagy-Mediated Toxicity Response.

Contaminant-bearing polystyrene microplastics (PSMPs) may exert significantly different toxicity profiles from their contaminant-free counterparts, with the role of PSMPs in promoting contaminant uptake being recognized. However, studies investigating the environmentally relevant exposure and toxic mechanisms of aged PSMPs binding to Cr are limited. Here, we show that loading of chromium (Cr) markedly alters the physicochemical properties and toxicological profiles of aged PSMPs. Specifically, Cr-bearing aged PSMPs induced severe body weight loss, oxidative stress (OS), autophagy, intestinal barrier injury, inflammation-pyroptosis response, and enteropathogen invasion in mice. Mechanistic investigations revealed that PSMPs@Cr exacerbated the OS, resulting in intestinal barrier damage and inflammation-pyroptosis response via overactivated Notch signaling and autophagy/cathepsin B/IL-1β pathway, respectively, which ultimately elevated mortality related to bacterial pathogen infection. In vitro experiments confirmed that autophagy-mediated reactive oxygen species (ROS) overproduction resulted in severe pyroptosis and impaired intestinal stem cells differentiation alongside the overactivation of Notch signaling in PSMPs@Cr-exposed organoids. Overall, our findings provide an insight into autophagy-modulated ROS overproduction within the acidic environment of autophagosomes, accelerating the release of free Cr from PSMPs@Cr and inducing secondary OS, revealing that PSMPs@Cr is a stable hazard material that induces intestinal injury. These findings provided a potential therapeutic target for environmental MPs pollution caused intestinal disease in patients.

Laminin-α2 chain deficiency in skeletal muscle causes dysregulation of multiple cellular mechanisms.

LAMA2, coding for the laminin-α2 chain, is a crucial ECM component, particularly abundant in skeletal muscle. Mutations in LAMA2 trigger the often-lethal LAMA2-congenital muscular dystrophy (LAMA2-CMD). Various phenotypes have been linked to LAMA2-CMD; nevertheless, the precise mechanisms that malfunction during disease onset in utero remain unknown. We generated Lama2-deficient C2C12 cells and found that Lama2-deficient myoblasts display proliferation, differentiation, and fusion defects, DNA damage, oxidative stress, and mitochondrial dysfunction. Moreover, fetal myoblasts isolated from the dy W mouse model of LAMA2-CMD display impaired differentiation and fusion in vitro. We also showed that disease onset during fetal development is characterized by a significant down-regulation of gene expression in muscle fibers, causing pronounced effects on cytoskeletal organization, muscle differentiation, and altered DNA repair and oxidative stress responses. Together, our findings provide unique insights into the critical importance of the laminin-α2 chain for muscle differentiation and muscle cell homeostasis.