Repression Of Differentiation Research Articles

Insect Cuticle Protein Nanoassemblies without Nonspecific Immune Response for Acute Methicillin-Resistant Staphylococcus aureus Pneumonia Remission.

The emergence and proliferation of methicillin-resistant Staphylococcus aureus (MRSA) pneumonia poses a significant global public health threat. Herein, the significant remission effect against acute MRSA pneumonia was realized through the insect cuticle protein (OfCPH-2) nanoassemblies without nonspecific immune response. The lung repair results could be attributed to the transforming of M1-type to M2-type macrophage polarization and the repression of Th17 cell differentiation in mice spleens through the intervention of OfCPH-2 nanoassemblies. These findings offer a valuable insight into the application of insect protein-based materials as effective antidrug resistant strain agents as well as a powerful strategy for acute MRSA pneumonia.

Lignin biosynthesis pathway repressors in gymnosperms: differential repressor domains as compared to angiosperms.

Lignin is a polyphenolic polymer present in the cell walls of specialized plant cell types in vascular plants that provides structural support and plays a major role in plant protection. The lignin biosynthesis pathway is regulated by transcription factors from the MYB (myeloblastosis) family. While several MYB members positively regulate lignin synthesis, only a few negatively regulate lignin synthesis. These lignin suppressors are well characterized in model plant species; however, their role has not been fully explored in gymnosperms. Lignin forms one of the major hurdles for the forest-based industry e.g. paper, pulp, and biofuel production. Therefore, the detailed mechanisms involved in the regulation of lignin synthesis are valuable, especially in conifers that form the major source of softwood for timber and paper production. In this review, the potential and differential domains present in the MYB suppressors in gymnosperms are discussed, along with their phylogenetic analysis. Sequence analysis revealed that the N-terminal regions of the MYB suppressor members were found to be conserved among the gymnosperms and angiosperms containing the R2, R3, and bHLH domains, while the C-terminal regions were found to be highly variable. The typical repressor motifs like the LxLxL-type EAR motif and the TLLLFR motif were absent from the C-terminal regions of MYB suppressors from most gymnosperms. However, although the gymnosperms lacked the characteristic repressor domains, a R2R3-type MYB member from Ginkgo was reported to repress the lignin biosynthetic pathway. It is proposed that gymnosperms possess unique kinds of repressors that need further functional validation.

Subconjunctival injection of human umbilical cord mesenchymal stem cells alleviates experimental allergic conjunctivitis via regulating T cell response

BackgroundT helper 2 (Th2) cells are thought to play critical roles in allergic conjunctivitis (AC). They release inflammatory cytokines to promote an allergic response in AC. Due to individual heterogeneity and long-term chronic management, current therapies do not always effectively control AC. Mesenchymal stem cells (MSCs) have been shown to be effective in treating allergy-related disorders, but it is unclear how exactly the Th2-mediated allergic response is attenuated. This study aims to elucidate the therapeutic effect and mechanism of the human umbilical cord MSCs (hUCMSCs) in a mouse model of experimental AC (EAC).MethodsA mouse EAC model was established by inoculating short ragweed (SRW) pollen. After the SRW pollen challenge, the mice received a single subconjunctival or tail vein injection of 2 × 106 hUCMSCs, or subconjunctival injection of hUCMSCs conditioned medium (hUCMSC-CM), and dexamethasone eye drops was used as positive control; subsequent scratching behavior and clinical symptoms were assessed. Immunostaining and flow cytometry were carried out to show allergic reactions and the activation of CD4 + T cell subsets in the conjunctiva and cervical lymph nodes (CLNs). Gene expression was determined by RNA-seq and further verified by qRT-PCR and Western blot. Co-culture assays were performed to explore the regulatory role of hUCMSCs in the differentiation of CD4 + naive T cells (Th0) into Th2 cells.ResultsSubconjunctival administration of hUCMSCs resulted in fewer instances of scratching and lower inflammation scores in EAC mice compared to the tail vein delivery, hUCMSC-CM and control groups. Subconjunctival administration of hUCMSCs reduced the number of activated mast cells and infiltrated eosinophils in the conjunctiva, as well as decreased the number of Th2 cells in CLNs. After pretreatment with EAC mouse serum in vitro to mimic the in vivo milieu, hUCMSCs were able to inhibit the differentiation of Th0 into Th2 cells. Further evidence demonstrated that repression of Th2 cell differentiation by hUCMSCs is mediated by CRISPLD2 through downregulation of STAT6 phosphorylation. Additionally, hUMCSCs were able to promote the differentiation of Th0 cells into regulatory T cells in CLNs of EAC mice.ConclusionsSubconjunctival injection of hUCMSCs suppressed the Th2-allergic response and alleviated clinical symptoms. This study provides not only a potential therapeutic target for the treatment of AC but also other T cell-mediated diseases.

Long noncoding RNA TUG1 regulates smooth muscle cell differentiation via KLF4-myocardin axis.

Abdominal aortic aneurysms (AAAs) are asymptomatic vascular diseases that have life-threatening outcomes. Smooth muscle cell (SMC) dysfunction plays an important role in AAA development. The contribution of non-coding genome, specifically the role of long non-coding RNAs (lncRNAs) in SMC dysfunction, is relatively unexplored. We investigated the role of lncRNA TUG1 in SMC dysfunction. To identify potential lncRNAs relevant to SMC functionality, lncRNA profiling was performed in angiotensin-II-treated SMCs. AAA was induced by angiotensin-II treatment in mice. Transcriptional regulation of TUG1 was studied using promoter luciferase and chromatin-immuno-precipitation experiments. Gain-or-loss-of-function experiments were performed in vitro to investigate TUG1-mediated regulation of SMC function. Immunoprecipitation experiments were conducted to elucidate the mechanism underlying TUG1-mediated SMC dysfunction. TUG1 was upregulated in SMCs following angiotensin-II treatment. Similarly, TUG1 levels were elevated in abdominal aorta in a mouse model of angiotensin-II-induced AAA. Further investigations showed that angiotensin-II-induced TUG1 expression could be suppressed by inhibiting Notch-signaling pathway, both in vitro and in mouse AAA model and that TUG1 is a direct transcriptional target of the Notch pathway. In aneurysmal tissues, TUG1 expression was inversely correlated with the expression of SMC contractile genes. Overexpression of TUG1 repressed SMC differentiation in vitro, whereas siRNA/shRNA-mediated TUG1 knockdown showed an opposite effect. Mechanistically, TUG1 interacts with transcriptional repressor KLF4 and facilitates its recruitment to myocardin promoter ultimately leading to the repression of SMC differentiation. In summary, our study uncovers a novel role for the lncRNA TUG1 wherein it modulates SMC differentiation via the KLF4-myocardin axis, which may have potential implications in AAA development.NEW & NOTEWORTHY TUG1 is an angiotensin-II-induced long noncoding RNA that mediates smooth muscle cell (SMC) dysfunction through interaction with transcriptional repressor KLF4.

MiR-222-3p suppresses C2C12 myoblast proliferation and differentiation via the inhibition of IRS-1/PI3K/Akt pathway.

Numerous studies have revealed the profound impact of microRNAs on regulating skeletal muscle development and regeneration. However, the biological function and regulation mechanism of miR-222-3p in skeletal muscle remains largely unknown. In this study, miR-222-3p was found to be abundantly expressed in the impaired skeletal muscles, indicating that it might have function in the development and regeneration process of the skeletal muscle. MiR-222-3p overexpression impeded C2C12 myoblast proliferation and myogenic differentiation, whereas inhibition of miR-222-3p got the opposite results. The dual-luciferase reporter assay showed that insulin receptor substrate-1 (IRS-1) was the target gene of miR-222-3p. We next found that knockdown of IRS-1 could obviously suppress C2C12 myoblast proliferation and differentiation. Additionally, miR-222-3p-induced repression of myoblast proliferation and differentiation was verified to be associated with a decrease in phosphoinositide 3-kinase (PI3K)-Akt signaling. Overall, we demonstrated that miR-222-3p inhibited C2C12 cells myogenesis via IRS-1/PI3K/Akt pathway. Therefore, miR-222-3p may be used as a therapeutic target for alleviating muscle loss caused by inherited and nonhereditary diseases.

Epidermal growth factor represses differentiation of mouse trophoblast stem cells into spongiotrophoblast cells via epidermal growth factor receptor

The mouse placenta is composed of three different trophoblast layers that are occupied by particular trophoblast subtypes to maintain placental function and pregnancy. Accurate control of trophoblast differentiation is required for proper placental function; however, the molecular mechanisms underlying cell fate decisions in trophoblast stem cells remain poorly understood. Epidermal growth factor (EGF) signaling is involved in multiple biological processes including cell survival, proliferation, and differentiation. The effect of EGF on trophoblast function has been reported in various species; however, the role of EGF signaling in mouse trophoblast specification remains unclear. In this study, we aimed to elucidate the role of EGF signaling in mouse trophoblast differentiation using mouse trophoblast stem cells (mTSCs) in an in vitro culture system. EGF stimulation at the early stage of differentiation repressed mTSC differentiation into spongiotrophoblast cells (SpT). Gene deletion and inhibitor experiments showed that the effect of EGF exposure went through epidermal growth factor receptor (Egfr) activity in mTSCs. EGF stimuli induced acute downstream activation of MAPK/ERK, PI3K/AKT, and JNK pathways, and inhibition of the MAPK/ERK pathway, but not others, alleviated EGF-mediated repression of SpT differentiation. Moreover, expression of Mash2, a master regulator of SpT differentiation, was repressed by EGF stimulation, and MAPK/ERK inhibition counteracted this repression. The Mash2 overexpression recovered SpT marker expression, indicating that the decrease in Mash2 expression was due to abnormal SpT differentiation in EGF-treated mTSCs. Our findings suggest that the EGF-Egfr-MAPK/ERK-Mash2 axis is a core regulatory mechanism for the EGF-mediated repression of SpT differentiation.

Differentiation Scoring (DS) Derived from Cellworks Computational Omics Biology Model (CBM) Predicts Response to Hypomethylating Agents (HMA) and Patient Survival in Myelodysplastic Syndrome (MDS)

Background: Differentiation arrest resulting from aberrant methylation represents a key pathogenic and phenotypic feature of MDS. Hypomethylating agents (HMA) can reverse epigenetic dysregulation, but as single agents fail to control the disease in approximately 50% of patients, many of whom progress to AML and carry a dismal prognosis. We hypothesized that Differentiation Scoring (DS) derived from Cellworks Computational Omics Biology Model (CBM) of each patient's genomic aberrations could serve as a biomarker to predict response to HMA. Methods: We studied 169 MDS patients treated with azacytidine (n = 86) or decitabine (n = 83) whose genomic aberrations and clinical outcomes were available from public databases. Biosimulation of the disease state was computationally derived from pathways that were up- or down-regulated by individual genomic aberrations. DS was defined as the ratio of the quantified impact of key differentiation biomarkers in myeloid malignancies (CEBPA, GATA1, SPI1 and ITGAM) divided by the impact of HOXA9 transcription, a known repressor of differentiation, and normalized on a log2 scale. We also used CBM to determine the change in DS attributable to HMA to define an efficacy score (ES) as a parameter of drug response. A Pearson correlation coefficient was obtained using the two variables. DS in clinical responders (R) and non-responders (NR) was evaluated with the Student t-test. We defined DS > 1.5 as DS-high and < 1.5 as DS-low. Survival data were available for 101 patients and correlated with DS-high (n=49) and DS-low (n=52) groups using a KM-curve. Results: Median age of this cohort was 69 years (range, 20-87 years), including 56 females, 111 males, and 2 of unknown sex. Regarding HMA response, 62 patients were R while 107 were NR. Prior to therapy, 86 patients had DS-high and 83 had DS-low scores. Post-treatment DS were correlated with HMA ES (R = 0.58, p < 2.2e-16), and showed a favorable HMA response for DS-high patients. Biosimulation showed the incremental benefit on DS of HMA was greater for people with DS-high than DS-low scores (44% vs 16%, p = 7.51 e-17). Median DS was higher in R than NR (p=0.00232). Patients with DS-high scores had superior survival compared to those with DS-low scores (log rank p = 0.0016). (Figure 1a) Different genomic aberrations contributed to the DS scores. DS-high patients had more TP53 mutations, 17p del, 8q amp, and 5q del. On the other hand, DS-low patients more often had mutations in ASXL1, SRSF2, RUNX1, DNMT3A, EZH2, NF1, NRAS, CBL, or 7q deletion. (Figure 1b) Loss of TP53 due to mutation or deletion upregulates DNMT1 and silences HOXA9 transcription, leading to DS-high scores. KAT6A (8q) amp also upregulates EZH2 and CpG methylation, while 5q del causes GATA1 transcription, increasing CpG methylation via SALL4 to produce high ß-catenin signaling that led to DS-high scores. By contrast, 7q loss, ASXL1, SRSF2, and EZH2 mutations downregulated EZH2, diminished CpG methylation and unsilenced HOXA9 transcription. As a result, HOXA9 arrested differentiation results in DS-low scores. Additionally, NF1 or NRAS mutations upregulate ERK signaling which inhibits CEBPA, and also caused DS-low scores. Conclusions: Computational biosimulation based on patients’ individual genomic aberrations reveals a spectrum of DS among patients with MDS. DS strongly predicted HMA response. In general, NR had lower DS and survival than DS-high patients. While patients with DS-low scores might have fared even worse without HMA therapy, we propose that DS-low patients should be considered for novel combination therapy at the time of diagnosis given their unsatisfactory outcomes with HMA therapy as a single agent. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

HUC-MSCs Attenuate Acute Graft-Versus-Host Disease through Chi3l1 Repression of Th17 Differentiation.

Mesenchymal stem cells (MSCs) have already demonstrated definitive evidence of their clinical benefits in acute graft-versus-host disease (aGvHD) and other inflammatory diseases. However, the comprehensive mechanism of MSCs' immunomodulation properties has not been elucidated. To reveal their potential immunosuppressive molecules, we used RNA sequencing to analyze gene expression in different tissue-derived MSCs, including human bone marrow, umbilical cord, amniotic membrane, and placenta, and found that chitinase-3-like protein 1 (Chi3l1) was highly expressed in human umbilical cord mesenchymal stem cells (hUC-MSCs). We found that hUC-MSCs treated with interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) exhibited increased expression of Chi3l1 and concurrently repressed T-helper 17 cell (Th17) differentiation through inhibition of signal transducer and activator of transcription 3 (STAT3) activation. Furthermore, Chi3l1 knockdown hUC-MSCs exhibited impaired therapeutic efficacy in aGvHD mice with an increased inflammatory response by promoting Th17 cell differentiation, including an increase in IL-17A in the spleen, intestine, and serum. Collectively, these results reveal a new immunosuppressive molecule, Chi3l1, in hUC-MSCs in the treatment of aGvHD that regulates Th17 differentiation and inhibits STAT3 activation. These novel insights into the mechanisms of hUC-MSC immunoregulation may lead to the consistent production of hUC-MSCs with strong immunosuppressive functions and thus improved clinical utility.

Disruption of β-catenin-mediated negative feedback reinforces cAMP-induced neuronal differentiation in glioma stem cells

Accumulating evidence supports the existence of glioma stem cells (GSCs) and their critical role in the resistance to conventional treatments for glioblastoma multiforme (GBM). Differentiation therapy represents a promising alternative strategy against GBM by forcing GSCs to exit the cell cycle and reach terminal differentiation. In this study, we demonstrated that cAMP triggered neuronal differentiation and compromised the self-renewal capacity in GSCs. In addition, cAMP induced negative feedback to antagonize the differentiation process by activating β-catenin pathway. Suppression of β-catenin signaling synergized with cAMP activators to eliminate GSCs in vitro and extended the survival of animals in vivo. The cAMP/PKA pathway stabilized β-catenin through direct phosphorylation of the molecule and inhibition of GSK-3β. The activated β-catenin translocated into the nucleus and promoted the transcription of APELA and CARD16, which were found to be responsible for the repression of cAMP-induced differentiation in GSCs. Overall, our findings identified a negative feedback mechanism for cAMP-induced differentiation in GSCs and provided potential targets for the reinforcement of differentiation therapy for GBM.

Pregnane X receptor (PXR) represses osteoblast differentiation through repression of the Hedgehog signaling pathway

The pregnane X receptor (PXR, NR1I2) belongs to the nuclear receptor family and functions as a xenobiotic and endobiotic sensor by binding to various molecules through its relatively flexible ligand-binding domain. In addition to these well-known canonical roles, we previously reported that PXR represses osteoblast differentiation. However, the mechanisms underlying the PXR-mediated repression of osteoblast differentiation remains unknown. In this study, we analyzed the changes in global gene expression profiles induced by PXR in calvarial osteoblasts cultured in standard fetal bovine serum (in which PXR induces repression of differentiation), and in those cultured in charcoal-stripped fetal bovine serum (in which PXR does not induce repression of differentiation). The comparison revealed that PXR attenuated the Hedgehog-mediated signaling in culture conditions that induced PXR-mediated repression of differentiation. Real-time PCR analysis showed that PXR repressed the Hedgehog signaling-induced genes such as Gli1 and Hhip, and conversely induced the Hedgehog signaling-repressed genes such as Cdon, Boc, and Gas1. Activation of Smo-mediated signaling in osteoblasts following treatment with a Smo agonist (SAG) significantly restored Gli-mediated transcriptional activity and osteoblast differentiation. Our results demonstrate the osteoblast-autonomous effects of PXR and identify a novel regulation of Hedgehog signaling by nuclear receptors.

Carboxamide Derivatives Are Potential Therapeutic AHR Ligands for Restoring IL-4 Mediated Repression of Epidermal Differentiation Proteins.

Atopic dermatitis (AD) is a common T-helper 2 (Th2) lymphocyte-mediated chronic inflammatory skin disease characterized by disturbed epidermal differentiation (e.g., filaggrin (FLG) expression) and diminished skin barrier function. Therapeutics targeting the aryl hydrocarbon receptor (AHR), such as coal tar and tapinarof, are effective in AD, yet new receptor ligands with improved potency or bioavailability are in demand to expand the AHR-targeting therapeutic arsenal. We found that carboxamide derivatives from laquinimod, tasquinimod, and roquinimex can activate AHR signaling at low nanomolar concentrations. Tasquinimod derivative (IMA-06504) and its prodrug (IMA-07101) provided full agonist activity and were most effective to induce FLG and other epidermal differentiation proteins, and counteracted IL-4 mediated repression of terminal differentiation. Partial agonist activity by other derivatives was less efficacious. The previously reported beneficial safety profile of these novel small molecules, and the herein reported therapeutic potential of specific carboxamide derivatives, provides a solid rationale for further preclinical assertation.

SIX1 reprograms myogenic transcription factors to maintain the rhabdomyosarcoma undifferentiated state.

SUMMARYRhabdomyosarcoma (RMS) is a pediatric muscle sarcoma characterized by expression of the myogenic line-age transcription factors (TFs) MYOD1 and MYOG. Despite high expression of these TFs, RMS cells fail to terminally differentiate, suggesting the presence of factors that alter their functions. Here, we demonstrate that the developmental TF SIX1 is highly expressed in RMS and critical for maintaining a muscle progenitor-like state. SIX1 loss induces differentiation of RMS cells into myotube-like cells and impedes tumor growth in vivo. We show that SIX1 maintains the RMS undifferentiated state by controlling enhancer activity and MYOD1 occupancy at loci more permissive to tumor growth over muscle differentiation. Finally, we demonstrate that a gene signature derived from SIX1 loss correlates with differentiation status and predicts RMS progression in human disease. Our findings demonstrate a master regulatory role of SIX1 in repression of RMS differentiation via genome-wide alterations in MYOD1 and MYOG-mediated transcription.

The dual distinct role of telomerase in repression of senescence and myofibroblast differentiation.

Many aging related diseases such as cancer implicate the myofibroblast in disease progression. Furthermore genesis of the myofibroblast is associated with manifestation of cellular senescence of unclear significance. In this study we investigated the role of a common regulator, namely telomerase reverse transcriptase (TERT), in order to evaluate the potential significance of this association between both processes. We analyzed the effects of TERT overexpression or deficiency on expression of CDKN2A and ACTA2 as indicators of senescence and differentiation, respectively. We assess binding of TERT or YB-1, a repressor of both genes, to their promoters. TERT repressed both CDKN2A and ACTA2 expression, and abolished stress-induced expression of both genes. Conversely, TERT deficiency enhanced their expression. Altering CDKN2A expression had no effect on ACTA2 expression. Both TERT and YB-1 were shown to bind the CDKN2A promoter but only YB-1 was shown to bind the ACTA2 promoter. TERT overexpression inhibited CDKN2A promoter activity while stimulating YB-1 expression and activation to repress ACTA2 gene. TERT repressed myofibroblast differentiation and senescence via distinct mechanisms. The latter was associated with TERT binding to the CDKN2A promoter, but not to the ACTA2 promoter, which may require interaction with co-factors such as YB-1.

The Notch Signaling Pathway and Breast Cancer: The Importance of Balance and Cellular Self-Control

Background:Notch is a cell signaling pathway that is highly conserved in all metazoans and is the master responsible for cell differentiation and cross communication with other signaling pathways such as Wingless and Hedgehog. In most cancers, the Notch signaling pathway is altered, causing normal controls of vital processes such as cell cycle, differentiation and apoptosis to be compromised, leading the cell to a carcinogenic state. However, the inherent nature of the Notch signaling pathway of regulating the activation or repression of other signaling pathways related to differentiation and cell cycle has caused the strategies against breast cancer to be even more specialized and to know more efficiently the suitable method againts the disease.Methods:Different bibliographies and articles related to the Notch pathway and the biology of cancer were reviewed, especially with breast cancer, as well as the participation of other signaling pathways directly and indirectly related to the constitutive activation of the Notch pathway and relating the threads loose to create a general conceptual map of the wide effects of the malfunction of the Notch pathway in this disease so that we can understand from another point of view how this flow of information can be controlled.Results:The study of Notch signaling during more than a decade has gave us new clues to elucidate the mechanisms of their finely orchestrated molecular functioning and how this signaling path interacts with another signaling pathways in differentiation, survival, cell cycle and apoptosis. Notch Signaling is a professional in the process of differentiation and cross-talk communication with another signaling pathways, especially with the WNT and Hh pathways. The responsibility of WNT pathway is to maintain the survival and growth controls, having direct effects on the cell cycle and the Hh pathway is to maintain a state of diferentiation trought the life of the cell and the cell migration instead, cell cycle and the response to growth stimuli of angiogenesis, exacerbated characteristics of many breast cancer.Conclusion:This review highlights the complex communication network between the WNT, Hh and Notch Signaling and the therapies in the field of cancer that are not entirely effective, however, most of the therapies that are currently being developed are including the Notch Signaling as a target quite promising and is for its regulatory effect with other signaling pathways.

Arbutin ameliorates glucocorticoid-induced osteoporosis through activating autophagy in osteoblasts.

Chronic long-term glucocorticoid use causes osteoporosis partly by interrupting osteoblast homeostasis and exacerbating bone loss. Arbutin, a natural hydroquinone glycoside, has been reported to have biological activities related to the differentiation of osteoblasts and osteoclasts. However, the role and underlying mechanism of arbutin in glucocorticoid-induced osteoporosis are elusive. In this study, we demonstrated that arbutin administration ameliorated osteoporotic disorders in glucocorticoid dexamethasone (Dex)-induced mouse model, including attenuating the loss of bone mass and trabecular microstructure, promoting bone formation, suppressing bone resorption, and activating autophagy in bone tissues. Furthermore, Dex-stimulated mouse osteoblastic MC3T3-E1 cells were treated with arbutin. Arbutin treatment rescued Dex-induced repression of osteoblast differentiation and mineralization, the downregulation of osteogenic gene expression, reduced autophagic marker expression, and decreased autophagic puncta formation. The application of autophagy inhibitor 3-MA decreased autophagy, differentiation, and mineralization of MC3T3-E1 cells triggered by arbutin. Taken together, our findings suggest that arbutin treatment fends off glucocorticoid-induced osteoporosis, partly through promoting differentiation and mineralization of osteoblasts by autophagy activation.

Age-related changes in polycomb gene regulation disrupt lineage fidelity in intestinal stem cells.

Tissue homeostasis requires long-term lineage fidelity of somatic stem cells. Whether and how age-related changes in somatic stem cells impact the faithful execution of lineage decisions remains largely unknown. Here, we address this question using genome-wide chromatin accessibility and transcriptome analysis as well as single-cell RNA-seq to explore stem-cell-intrinsic changes in the aging Drosophila intestine. These studies indicate that in stem cells of old flies, promoters of Polycomb (Pc) target genes become differentially accessible, resulting in the increased expression of enteroendocrine (EE) cell specification genes. Consistently, we find age-related changes in the composition of the EE progenitor cell population in aging intestines, as well as a significant increase in the proportion of EE-specified intestinal stem cells (ISCs) and progenitors in aging flies. We further confirm that Pc-mediated chromatin regulation is a critical determinant of EE cell specification in the Drosophila intestine. Pc is required to maintain expression of stem cell genes while ensuring repression of differentiation and specification genes. Our results identify Pc group proteins as central regulators of lineage identity in the intestinal epithelium and highlight the impact of age-related decline in chromatin regulation on tissue homeostasis.

Cellular Mechanism Underlying Highly-Active or Antiretroviral Therapy-Induced Lipodystrophy: Atazanavir, a Protease Inhibitor, Compromises Adipogenic Conversion of Adipose-Derived Stem/Progenitor Cells through Accelerating ER Stress-Mediated Cell Death in Differentiating Adipocytes.

Lipodystrophy is a common complication in human immunodeficiency virus (HIV)-infected patients receiving highly active antiretroviral therapy (HAART) or antiretroviral therapy (ART). Previous studies demonstrated that endoplasmic reticulum (ER) stress-mediated unfolded protein response (UPR) is involved in lipodystrophy; however, the detailed mechanism has not been fully described in human adipogenic cell lineage. We utilized adipose tissue-derived stem cells (ADSCs) obtained from human subcutaneous adipose tissue, and atazanavir (ATV), a protease inhibitor (PI), was administered to ADSCs and ADSCs undergoing adipogenic conversion. Marked repression of adipogenic differentiation was observed when ATV was administered during 10 days of ADSC culture in adipogenic differentiation medium. Although ATV had no effect on ADSCs, it significantly induced apoptosis in differentiating adipocytes. ATV treatment also caused the punctate appearance of CCAAT-enhancer-binding (C/EBP) protein homologous protein (CHOP), and altered expression of CHOP and GRP78/Bip, which are the representation of ER stress, only in differentiating adipocytes. Administration of UPR inhibitors restored adipogenic differentiation, indicating that ER stress-mediated UPR was induced in differentiating adipocytes in the presence of ATV. We also observed autophagy, which was potentiated in differentiating adipocytes by ATV treatment. Thus, adipogenic cell atrophy leads to ATV-induced lipodystrophy, which is mediated by ER stress-mediated UPR and accelerated autophagy, both of which would cause adipogenic apoptosis. As our study demonstrated for the first time that ADSCs are unsusceptible to ATV and its deleterious effects are limited to the differentiating adipocytes, responsible target(s) for ATV-induced lipodystrophy may be protease(s) processing adipogenesis-specific protein(s).

The KDM5 Inhibitor KDM5-C70 Induces Astrocyte Differentiation in Rat Neural Stem Cells.

Members of the lysine-specific histone demethylase 5 (KDM5/JARID1) family are known to play important roles in stem cell fate determination. Here, using the KDM5 inhibitor C70 (KDM5-C70), we demonstrated that the histone demethylase activity of the KDM5 enzyme is essential for the repression of astrocytic differentiation of neural stem cells (NSCs). KDM5-C70 treatment activated the glial fibrillary acidic protein (Gfap) gene by increasing the trimethylation of histone H3 lysine 4 in the promoter regions and subsequently induced astrocytogenesis in NSCs. In addition, treatment of NSCs with KDM5-C70 activated Janus kinase-signal transducer and activator of transcription (JAK-STAT3) signaling and increased the mRNA expression of transforming growth factor-beta 1 (Tgf-β1). Our data provide evidence that KDM5 is a promising target for NSC fate modulation and suggest that epigenetic regulation is important for NSC fate determination.

521. Similarities and Differences in Transcriptomic Host Response between SARS-CoV-2 and Other Viral Infections

BackgroundCOVID-19 is a pandemic caused by the SARS-CoV-2 virus that shares and differs in clinical characteristics of known viral infections.MethodsWe obtained RNAseq profiles of 62 prospectively enrolled COVID-19 patients and 24 healthy controls (HC). We collected 23 independent studies profiling 1,855 blood samples from patients covering six viruses (influenza, RSV, HRV, Ebola, Dengue and SARS-CoV-1). We studied host whole-blood transcriptomic responses in COVID-19 compared to non-COVID-19 viral infections to understand similarities and differences in host response. Gene signature threshold was absolute effect size ≥1, FDR ≤ 0.05%.ResultsDifferential gene expression of COVID-19 vs HC are highly correlated with non-COVID-19 vs HC (r=0.74, p< 0.001). We discovered two gene signatures: COVID-19 vs HC (2002 genes) (COVIDsig) and non-COVID-19 vs HC (635 genes) (nonCOVIDsig). Pathway analysis of over-expressed signature genes in COVIDsig or nonCOVIDsig identified similar pathways including neutrophil activation, innate immune response, immune response to viral infection and cytokine production. Conversely, for under-expressed genes, pathways indicated repression of lymphocyte differentiation and activation (Fig1).Intersecting the two gene signatures found two genes significantly oppositely regulated (ACO1, ATL3). We derived a third gene signature using COCONUT to compare COVID-19 to non-COVID-19 viral infections (416 genes) (Fig2). Pathway analysis did not result in significant enrichment, suggesting identification of novel biology (Fig1).Statistical deconvolution of bulk transcriptomic data found M1 macrophages, plasmacytoid dendritic cells, CD14+ monocytes, CD4+ T cells and total B cells changed in the same direction across COVID-19 and non-COVID-19 infections. Cell types that increased in COVID-19 relative to non-COVID-19 were CD56bright NK cells, M2 macrophages and total NK cells. Those that decreased in non-COVID-19 relative to COVID-19 were CD56dim NK cells & memory B cells and eosinophils (Fig3).Figure 1 Figure 2 Figure 3 ConclusionThe concordant and discordant responses mapped here provide a window to explore the pathophysiology of COVID-19 vs other viral infections and show clear differences in signaling pathways and cellularity as part of the host response to SARS-CoV-2.DisclosuresSimone A. Thair, PhD, Inflammatix, Inc. (Employee, Shareholder) Yudong He, PhD, Inflammatix Inc. (Employee) Yehudit Hasin-Brumshtein, PhD, Inflammatix (Employee, Shareholder) Suraj Sakaram, MS in Biochemistry and Molecular Biology, Inflammatix (Employee, Other Financial or Material Support, stock options) Rushika R. Pandya, MS, Inflammatix Inc. (Employee, Shareholder) David C. Rawling, PhD, Inflammatix Inc. (Employee, Shareholder) Purvesh Khatri, PhD, Inflammatix Inc. (Shareholder) Timothy Sweeney, MD, PHD, Inflammatix, Inc. (Employee, Shareholder)

The Transcription Factor p63 Is a Direct Effector of IL-4– and IL-13–Mediated Repression of Keratinocyte Differentiation

Atopic Dermatitis is an inflammatory skin disease associated with broad defects in skin barrier function caused by increased levels of type-2 cytokines (IL-4 and IL-13) that repress keratinocyte (KC) differentiation. Although crucial in mediating allergic disease, the mechanisms for gene repression induced by type-2 cytokines remain unclear. In this study, we determined that gene repression requires the master regulator of the epidermal differentiation program, p63. We found that type-2 cytokine-mediated inhibition of the expression of genes involved in early KC differentiation, including keratin 1, keratin 10, and DSC-1, is reversed by p63 blockade. Type-2 cytokines, through p63, also regulate additional genes involved in KC differentiation, including CHAC-1, STC2, and CALML5. The regulation of the expression of these genes is ablated by p63 small interfering RNA as well. In addition, we found that IL-4 and IL-13 and Staphylococcus aureus lipoteichoic acid work in combination through p63 to further suppress the early KC differentiation program. Finally, we found that IL-4 and IL-13 also inhibit the activity of Notch, a transcription factor required to induce early KC differentiation. In conclusion, type-2 cytokine-mediated gene repression and blockade of KC differentiation are multifactorial, involving pathways that converge on transcription factors critical for epidermal development, p63 and Notch.