Transcription Factor Runx2 Research Articles

Exosomes Derived from Dialysis Patients Serum enhance Endothelial-Mesenchymal Transition and Calcification in Endothelial Cells.

Vascular calcification (VC) is prevalent among patients with end stage kidney disease (ESKD). Exosomes, small extracellular vesicles actively secreted by cells, contain proteins, nucleic acids, lipids and other bioactive substances and are considered major mediators of cell-cell interactions. Endothelial-Mesenchymal Transition (EndMT) has been observed in a variety of pathological conditions, such as abnormal shear stress, vascular damage, and chronic inflammation. The aim of this research was to assess the effects of serum-derived exosomes from ESKD patients with VC on the induction of EndMT in endothelial cells and their potential role in accelerating VC. Twenty hemodialysis patients with VC and 10 healthy volunteers were recruited. Cardiac and brain VC were assessed among patients with ESKD treated with dialysis. Serum samples were taken at dialysis initiation for exosome isolation. Human umbilical vein endothelial cells (HUVEC) were treated with 100 µg/mL exosomes for 24-96 hours. At the end of incubation, cells were collected for mRNA and protein analysis. Exosomes isolated from dialysis patients with VC induced EndMT in HUVECs. After 24h, endothelial markers CD31 and VE-cadherin were decreased (31% and 51%, respectively; P<0.001) and the mesenchymal proteins Vimentin and N-cadherin were increased (283% and 156%, respectively; P<0.001), compared to healthy exosomes. After 96h of incubation, expression of genes essential for osteoblast differentiation, including the bone morphogenetic genes (BMP2, BMPR2, BMP4 and BMP9), and the transcription factor RUNX2 were significantly elevated. Exosomes derived from the serum of dialysis patients with VC, induced EndMT and contributed to calcification. The vicious cycle highlighted the intricate interplay between exosomes, EC and VC, emphasizing the critical necessity for therapeutic strategies to disrupt this pathway and mitigate calcification advancement.

Molecular and functional profiling unravels targetable vulnerabilities in colorectal cancer.

Colorectal cancer (CRC) patients with microsatellite-stable (MSS) tumors are mostly treated with chemotherapy. Clinical benefits of targeted therapies depend on mutational states and tumor location. Many tumors carry mutations in KRAS proto-oncogene, GTPase (KRAS) or B-Raf proto-oncogene, serine/threonine kinase (BRAF), rendering them more resistant to therapies. We performed whole-exome sequencing and RNA-Sequencing of 28 tumors of the Athens Comprehensive Cancer Center CRC cohort, and molecularly characterized CRC patients based on their microsatellite instability (MSI) status, single-nucleotide variations (SNVs)/copy number alterations (CNAs), and pathway/transcription factor activities at the individual patient level. Variants were classified using a computational score for integrative cancer variant annotation and prioritization. Complementing this with public multi-omics datasets, we identified activation of transforming growth factor beta (TGFβ) signaling to be more strongly activated in MSS patients, whereas Janus kinase (JAK)-signal transducer and activator of transcription (STAT) and mitogen-activated protein kinase (MAPK) molecular cascades were activated specifically in MSI tumors. We unraveled mechanisms consistently perturbed in the transcriptional and mutational circuits and identified Runt-related transcription factors (RUNX transcription factors) as putative biomarkers in CRC, given their role in the regulation of pathways involved in tumor progression and immune evasion. Assessing the immunogenicity of CRC tumors in the context of RAS/RAF mutations and MSI/MSS status revealed a critical impact that KRAS mutations have on immunogenicity, particularly in the MSS patient subgroup, with implications for diagnosis and treatment.

PROTAC-Mediated GSPT1 Degradation Impairs the Expression of Fusion Genes in Acute Myeloid Leukemia.

Proteolysis targeting chimeras (PROTACs) are heterobifunctional small molecules that utilize the ubiquitin-proteasome system to selectively degrade target proteins. This innovative technology has shown remarkable efficacy and specificity in degrading oncogenic proteins and has progressed through various stages of preclinical and clinical development for hematologic malignancies, including adult acute myeloid leukemia (AML). However, the application of PROTACs in pediatric AML remains largely unexplored. In this study, we show the potent effect of GSPT1 degradation against AML cells induced by either a GSPT1-selective cereblon modulator CC-90009 or by an off-target effect caused by a CDK6-PROTAC named GU3341. Both in vitro and ex vivo experiments revealed that GSPT1 degradation significantly inhibited tumor growth, induced cell cycle arrest, and triggered apoptosis in two pediatric AML subtypes characterized by RUNX1::RUNX1T1 and FUS::ERG fusion genes. Furthermore, the degradation of GSPT1 impaired the expression of RUNX1::RUNX1T1 and its cooperating transcription factors RUNX1 and ERG. Similarly, GSPT1 degradation also reduced FUS::ERG fusion transcript levels in AML cells harboring the translocation t(16;24)(p11:q22). These findings suggest a new role of GSPT1 in regulating leukemic transcriptional networks and open a new therapeutic strategy to target leukemic fusion genes in pediatric AML patients.

Runx2-NLRP3 axis orchestrates matrix stiffness-evoked vascular smooth muscle cell inflammation.

Arterial stiffening is a hallmark of chronic kidney disease (CKD)-related cardiovascular events and is primarily attributed to the elevated matrix stiffness. Stiffened arteries are accompanied by low-grade inflammation, but the causal effects of matrix stiffness on inflammation remain unknown. For analysis of the relationship between arterial stiffness and vascular inflammation, pulse-wave velocity (PWV) and aortic inflammatory markers were analyzed in an adenine-induced mouse model of CKD in chronological order. Compared with their control littermates, mice with CKD showed elevated arterial stiffness at the early stage of disease progression, which preceded the onset of vascular inflammation. Correspondingly, the increase of matrix stiffness induced vascular smooth muscle cells (VSMCs) to transdifferentiate into an inflammatory phenotype, as indicated by the increased expression and secretion of MCP-1, IL-6, IL-1β, and IL-18. RNA-sequencing analysis of stiff matrix-cultured VSMCs and bioinformatics analysis with the ChIP-Atlas database revealed the potential involvement of the transcription factor Runx2. The expression and the nuclear localization of Runx2 were significantly increased in stiff matrix-cultured VSMCs. High-throughput ChIP-sequencing and promoter luciferase assays further revealed that NLRP3 was directly transcriptionally regulated by Runx2. The inhibition of Runx2 or NLRP3 inflammasome abrogated the proinflammatory effect of matrix stiffening on VSMCs. Together, these data revealed that arterial stiffness precedes vascular inflammatory responses in CKD mice and that the Runx2-NLRP3 axis orchestrates matrix stiffness and the VSMC inflammatory phenotype, which may contribute to the pathogenic role in arterial stiffness-related vascular inflammation and CKD-related cardiovascular complications.NEW & NOTEWORTHY As a hallmark of chronic kidney disease (CKD), arterial stiffening is related to increased vascular inflammation and cardiovascular morbidity, whereas the underlying mechanism is unclear. The study demonstrates that increased arterial stiffness precedes the onset of vascular inflammation, and matrix stiffness stimulates the transdifferentiation of vascular smooth muscle cells (VSMCs) to an inflammatory phenotype via activating Runx2-NLRP3 signaling, which provides novel insights into CKD-related cardiovascular disorder treatment.

Lineage tracing studies suggest that the placenta is not a de novo source of hematopoietic stem cells.

Definitive hematopoietic stem and progenitor cells (HSPCs) arise from a small number of hemogenic endothelial cells (HECs) within the developing embryo. Understanding the origin and ontogeny of HSPCs is of considerable interest and potential therapeutic value. It has been proposed that the murine placenta contains HECs that differentiate into HSPCs. However, during human gestation HSPCs arise in the aorta considerably earlier than when they can first be detected in the placenta, suggesting that the placenta may primarily serve as a niche. We found that the Runx1 transcription factor, which is required to generate HSPCs from HECs, is not expressed by mouse placental ECs. To definitively determine whether the mouse placenta is a site of HSPC emergence, we performed lineage tracing experiments with a Hoxa13Cre allele that specifically labels ECs in the placenta and umbilical cord (UC), but not in the yolk sac or embryo. Immunostaining revealed Hoxa13Cre lineage-traced HECs and HSPCs in the UC, a known site of HECs, but not the placenta. Consistent with these findings, ECs harvested from the E10.5 aorta and UC, but not the placenta, gave rise to hematopoietic cells ex vivo, while colony forming assays using E14.5 fetal liver revealed only 2% of HSPCs arose from Hoxa13-expressing precursors. In contrast, the pan-EC Cdh5-CreERT2 allele labeled most HSPCs in the mouse placenta. Lastly, we found that RUNX1 and other HEC genes were not expressed in first-trimester human placenta villous ECs, suggesting that human placenta is not hemogenic. Our findings demonstrate that the placenta functions as a site for expansion of HSPCs that arise within the embryo proper and is not a primary site of HSPC emergence.

RUNX2 Phase Separation Mediates Long-Range Regulation Between Osteoporosis-Susceptibility Variant and XCR1 to Promote Osteoblast Differentiation.

GWASs have identified many loci associated with osteoporosis, but the underlying genetic regulatory mechanisms and the potential drug target need to be explored. Here, a new regulatory mechanism is found that a GWAS intergenic SNP (rs4683184) functions as an enhancer to influence the binding affinity of transcription factor RUNX2, whose phase separation can mediate the long-range chromatin interaction between enhancer and target gene XCR1 (a member of the GPCR family), leading to changes of XCR1 expression and osteoblast differentiation. Bone-targeting AAV of Xcr1 can improve bone formation in osteoporosis mice, suggesting that XCR1 can be a new susceptibility gene for osteoporosis. This study is the first to link non-coding SNP with phase separation, providing a new insight into long-range chromatin regulation mechanisms with susceptibility to complex diseases, and finding a potential target for the development of osteoporosis drugs and corresponding translational research.

Inflammatory microenvironment promotes extracellular matrix degradation of chondrocytes through ALKBH5-dependent Runx2 m6A modification in the pathogenesis of osteoarthritis

BackgroundOsteoarthritis (OA) is a chronic degenerative joint disease characterized by the breakdown of cartilage and extracellular matrix (ECM). The degradation of ECM in chondrocytes plays a crucial role in OA pathogenesis, but the underlying molecular mechanisms remain largely unclear. MethodsA sodium monoiodoacetate (MIA) mouse model was used to mimic OA. ECM integrity was accessed by Hematoxylin and Eosin (H&E) staining, Safranin O/fast green staining, and microcomputerized tomography. Enzyme-linked immunosorbent assay measured circulating proinflammatory cytokines. Reverse transcription-quantitative polymerase chain reaction and western blotting analyzed mRNA and protein expression levels. RNA and chromatin immunoprecipitation evaluated RNA-protein and DNA-protein interactions. ResultsMIA mice showed significant upregulation of the RNA m6A demethylase ALKBH5 (alkylated DNA repair protein AlkB homolog 5), the transcription factor Runx2 (runt-related transcription factor 2), and matrix-degrading enzymes Mmps (matrix metallopeptidase) and Adamts(s) (a disintegrin and metalloproteinase with thrombospondin motifs). In vitro, proinflammatory cytokines induced these proteins in chondrocytes. Mechanically, Alkbh5 cooperated with Ythdf1 (YTH N6-methyladenosine RNA binding protein 1) in the inflammatory microenvironment to regulate the expression and stability of RUNX2 mRNA. Runx2, in turn, activated the expression of MMPs and ADAMTSs, promoting ECM degradation in chondrocytes, thereby contributing to OA progression. Notably, inhibition of Alkbh5 and Runx2 in MIA-treated mice significantly alleviated the pathological progression of OA. ConclusionOur results reveal a novel mechanism of OA pathogenesis and suggest that targeting Alkbh5 and Runx2 may represent a new therapeutic strategy for OA treatment.

Transcriptional Regulation of the Human MGP Promoter: Identification of Downstream Repressors.

Matrix Gla protein (MGP) is a vitamin K-dependent γ-carboxylated protein that was initially identified as a physiological inhibitor of ectopic calcification, primarily affecting cartilage and the vascular system. Mutations in the MGP gene were found to be responsible for the Keutel syndrome, a condition characterized by abnormal calcifications in the cartilage, lungs, brain, and vascular system. MGP has been shown to be dysregulated in several tumors, including cervical, ovarian, urogenital, and breast cancers. Using bioinformatic approaches, transcription factor binding sites (TFBSs) containing CpG dinucleotides were identified in the MGP promoter, including those for YY1, GATA1, and C/EBPα. We carried out functional tests using transient transfections with a luciferase reporter assay, primarily for the transcription factors YY1, GATA1, C/EBPα, and RUNX2. By co-transfection analysis, we found that YY1, GATA1, and C/EBPα repressed the MGP promoter. Furthermore, the co-transfection with RUNX2 activated the MGP promoter. In addition, MGP expression is negatively or positively correlated with the studied TFs' expression levels in several cancer types. This study provides novel insights into MGP regulation by demonstrating that YY1, GATA1, and C/EBPα are negative regulators of the MGP promoter, and DNA methylation may influence their activity. The dysregulation of these mechanisms in cancer should be further elucidated.

Zinc Ameliorates High Pi and Ca-Mediated Osteogenic Differentiation of Mesenchymal Stem Cells.

Zinc is the second most abundant trace element in the human body, stored mainly in the bones. Zinc is required for bone growth and homeostasis and is also a crucial cofactor for numerous proteins that play key roles in maintaining microstructural integrity and bone remodeling. Bone marrow-derived mesenchymal stem cells (BMSCs) are multipotent progenitors found in the bone marrow stroma and can differentiate along multiple lineage pathways. In this study, we investigated the effect of zinc on the osteogenic differentiation of BMSCs. We stimulated the osteogenic differentiation of BMSCs with high phosphate and Ca-containing osteogenic medium (PiCa) in the presence or absence of zinc. We followed calcification by measuring ECM mineralization, the Ca content of the ECM, mRNA, and the protein expression of the osteo-chondrogenic transcription factor RUNX2 and SOX9 and its targets OCN and ALP. Zinc dose-dependently abolished PiCa-induced ECM mineralization and decreased the expression of RUNX2, SOX9, OCN, and ALP. Serum albumin did not alter the inhibitory effect of zinc on BMSC mineralization. Our further analysis with the zinc-chelator TPEN and ZnCl2 confirmed the specific inhibitory effect of free zinc ions on BMSC mineralization. Zinc inhibited phosphate uptake and PiCa-induced upregulation of the sodium-dependent phosphate cotransporters (PiT-1 and PiT-2). Zinc attenuated the PiCa-induced increase in ROS production. Taken together, these data suggest that zinc inhibits PiCa-induced BMSC calcification by regulating phosphate uptake and ROS production.

Combatting cellular immortality in cancers by targeting the shelterin protein complex

Shelterin proteins (TERF1, TERF2, TPP1, TINF2, POT1) protect telomeres, prevent unwarranted repair activation, and regulate telomerase activity. Alterations in these proteins can lead to cancer progression. This study uses an in-silico approach to examine shelterin in tumour samples across various cancers, employing mutation plots, phylogenetic trees, and sequence alignments. Network pharmacology identified TERF1 as an essential shelterin protein and transcription factors RUNX1, CTCF, and KDM2B as potential biomarkers due to their interactions with miRNAs and shelterin proteins. We performed MCODE analysis to identify subnetworks of ncRNAs interacting with the shelterin proteins. Shelterin expression predicted patient survival in 24 cancer types, with TERF1, TERF2, TINF2, and POT1 significantly expressed in testicular, AML, prostate, breast and renal cancers, respectively, and TPP1 in AML and skin cancer. Spearman and Pearson's analyses showed significant correlations of TERF1 across cancers, with near-significant correlations for all five proteins in different cancer datasets like breast cancer, kidney renal papillary and lung squamous cell carcinoma, skin cutaneous melanoma, etc.,. Shelterin expression correlated with patient survival in breast, renal, lung, skin, uterine, and gastric cancers. Insights into TPP1-associated glycans highlighted glycosylated sites contributing to tumorigenesis. This study provides molecular signatures for further functional and therapeutic research on shelterin, highlighting its potential as a target for anti-cancer therapies and promising prospects for cancer prognosis and prediction.

The co-receptor Neuropilin-1 enhances proliferation in inv(16) acute myeloid leukemia via VEGF signaling.

Oncogenic programs regulate the proliferation and maintenance of cancer stem cells, and can define pharmacologic dependencies. In acute myeloid leukemia (AML) with the chromosome inversion 16 (inv(16)), the fusion oncoproteinCBFβ::MYH11 regulates pathways associated with leukemia stem cell activity. Here we demonstrate that expression of Neuropilin-1 (NRP1) is regulated by the fusion oncoprotein, and promotes AML expansion. Mechanistically, we show that the NRP1 locus has open chromatin in inv(16) AML, and that CBFβ::MYH11 modulates the local function of the transcription factors ERG, GATA2 and RUNX1 to sustain NRP1 levels. We found that ERG activates NRP1 expression, and that CBFβ::MYH11 knockdown represses ERG expression, thereby allowing the repressive activity of GATA2/RUNX1 at three NRP1 enhancers. Functionally, we demonstrate that NRP1 enhances the expansion of leukemic cells in vitro and in mice, and that this activity is dependent on its VEGFR-associated FV/FVIII domain. Finally, we show that treatment with VEGF inhibitor axitinib reduces AML cell growth and delays median leukemia latency in vivo. Our findings reveal that the NRP1/VEGF axis mediates proliferation in inv(16) AML blasts, and suggest that targeting NRP1 function could be promising in combination AML therapy.

Hippo Signaling Pathway Involvement in Osteopotential Regulation of Murine Bone Marrow Cells Under Simulated Microgravity.

The development of osteopenia is one of the most noticeable manifestations of the adverse effects of space factors on crew members. The Hippo signaling pathway has been shown to play a central role in regulating the functional activity of cells through their response to mechanical stimuli. In the present study, the components of the Hippo pathway and the protective properties of osteodifferentiation inducers were investigated under simulated microgravity (smg) using a heterotypic bone marrow cell culture model, which allows for the maintenance of the close interaction between the stromal and hematopoietic compartments, present in vivo and of great importance for both the fate of osteoprogenitors and hematopoiesis. After 14 days of smg, the osteopotential and osteodifferentiation of bone marrow stromal progenitor cells, the expression of Hippo cascade genes and the immunocytochemical status of the adherent fraction of bone marrow cells, as well as the paracrine profile in the conditioned medium and the localization of Yap1 and Runx2 in mechanosensitive cells of the bone marrow were obtained. Simulated microgravity negatively affects stromal and hematopoietic cells when interacting in a heterotypic murine bone marrow cell culture. This is evidenced by the decrease in cell proliferation and osteopotential. Changes in the production of pleiotropic cytokines IL-6, GROβ and MCP-1 were revealed. Fourteen days of simulated microgravity induced a decrease in the nuclear translocation of Yap1 and the transcription factor Runx2 in the stromal cells of the intact group. Exposure to osteogenic induction conditions partially compensated for the negative effect of simulated microgravity. The data obtained will be crucial for understanding the effects of spaceflight on osteoprogenitor cell growth and differentiation via Hippo-Yap signaling.

Redistribution of PU.1 partner transcription factor RUNX1 binding secures cell survival during leukemogenesis

Transcription factors (TFs) orchestrating lineage-development often control genes required for cellular survival. However, it is not well understood how cells survive when such TFs are lost, for example in cancer. PU.1 is an essential TF for myeloid fate, and mice with downregulated PU.1 levels develop acute myeloid leukemia (AML). Combining a multi-omics approach with a functional genetic screen, we reveal that PU.1-downregulated cells fundamentally change their survival control from cytokine-driven pathways to overexpression of an autophagy-predominated stem cell gene program, for which we also find evidence in human AML. Control of this program involves redirected chromatin occupancy of the PU.1 partner TF Runx1 to a lineage-inappropriate binding site repertoire. Hence, genomic reallocation of TF binding upon loss of a partner TF can act as a pro-oncogenic failsafe mechanism by sustaining cell survival during leukemogenesis.

"A Friend Among Strangers" or the Ambiguous Roles of Runx2.

The transcription factor Runx2 plays a crucial role in regulating osteogenic differentiation and skeletal development. This factor not only controls the expression of genes involved in bone formation, but also interacts with signaling pathways such as the Notch pathway, which are essential for body development. However, studies have produced conflicting results regarding the relationship between Runx2 and the Notch pathway. Some studies suggest a synergistic interaction between these molecules, while others suggest an inhibitory one, for example, the interplay between Notch signaling, Runx2, and vitamin D3 in osteogenic differentiation and bone remodeling. The findings suggest a complex relationship between Notch signaling and osteogenic differentiation, with ongoing research needed to clarify the mechanisms involved and resolve existing contradictions regarding role of Notch in this process. Additionally, there is increasing evidence of contradictory roles for Runx2 in various tissues and organs, both under normal conditions and in pathological states. This diversity of roles makes Runx2 a potential therapeutic target, offering new directions for research. In this review, we have discussed the mechanisms of osteogenic differentiation and the important role of Runx2 in this process. We have also examined its relationship with different signaling pathways. However, there are still many uncertainties and inconsistencies in our current understanding of these interactions. Additionally, given that Runx2 is also involved in numerous other events in various tissues, we have tried to comprehensively examine its functions outside the skeletal system.

JMJD1C forms condensates to facilitate a RUNX1-dependent gene expression program shared by multiple types of AML cells.

JMJD1C, a member of the lysine demethylase 3 (KDM3) family, is universally required for the survival of several types of acute myeloid leukemia (AML) cells with different genetic mutations, representing a therapeutic opportunity with broad application. Yet how JMJD1C regulates the leukemic programs of various AML cells is largely unexplored. Here we show that JMJD1C interacts with the master hematopoietic transcription factor RUNX1, which thereby recruits JMJD1C to the genome to facilitate a RUNX1-driven transcriptional program that supports leukemic cell survival. The underlying mechanism hinges on the long N-terminal disordered region of JMJD1C, which harbors two inseparable abilities: condensate formation and direct interaction with RUNX1. This dual capability of JMJD1C may influence enhancer-promoter contacts crucial for the expression of key leukemic genes regulated by RUNX1. Our findings demonstrate a previously unappreciated role for the non-catalytic function of JMJD1C in transcriptional regulation, underlying a mechanism shared by different types of leukemias.

Ribosome biogenesis is essential for hemogenic endothelial cells to generate hematopoietic stem cells.

Undergoing endothelial-to-hematopoietic transition, a small fraction of embryonic aortic endothelial cells specializes into hemogenic endothelial cells (HECs) and eventually gives rise to hematopoietic stem cells (HSCs). Previously, we found that the activity of ribosome biogenesis (RiBi) is highly enriched in the HSC-primed HECs compared with adjacent arterial endothelial cells; however, whether RiBi is required in HECs for the generation of HSCs remains to be determined. Here, we have found that robust RiBi is markedly augmented during the endothelial-to-hematopoietic transition in mouse. Pharmacological inhibition of RiBi completely impeded the generation of HSCs in explant cultures. Moreover, disrupting RiBi selectively interrupted the HSC generation potential of HECs rather than T1 pre-HSCs, which was in line with its influence on cell cycle activity. Further investigation revealed that, upon HEC specification, the master transcription factor Runx1 dramatically bound to the loci of genes involved in RiBi, thereby facilitating this biological process. Taken together, our study provides functional evidence showing the indispensable role of RiBi in generating HSCs from HECs, providing previously unreported insights that may contribute to the improvement of HSC regeneration strategies.

Dynamic chromatin accessibility and transcriptome changes following PDGF-BB treatment of bone-marrow derived mesenchymal stem cells

BackgroundMesenchymal stem cells (MSCs) are multipotent stem cells that are under investigation for use in clinical trials because they are capable of self-renewal and differentiating into different cell types under defined conditions. Nonetheless, the therapeutic effects of MSCs have been constrained by low engraftment rates, cell fusion, and cell survival. Various strategies have been explored to improve the therapeutic efficacy of MSCs, with platelet-derived growth factor (PDGF)-BB emerging as a promising candidate. To enhance our comprehension of the impact of PDGF-BB on the gene expression profile and chromosomal accessibility of MSCs, RNA-sequencing and analysis of chromatin accessibility profiles were conducted on three human primary MSCs in culture, both with and without stimulation by PDGF-BB.ResultsIntegrative analysis of gene expression and chromatin accessibility demonstrated that PDGF-BB treatment modified the chromatin accessibility landscape, marking regions for activation or repression through the AP-1 family transcription factors TEAD, CEBP, and RUNX2. These changes in AP-1 transcription factor expression, in turn, led to cell proliferation and differentiation potential towards osteoblasts, adipocytes, or chondrocytes. The degree of MSC differentiation varies among cells isolated from different donors. The presence of an enrichment of exosome-related genes is also noted among all the differentially expressed genes.ConclusionsIn conclusion, the observed changes in AP-1 transcription factor expression not only induced cellular proliferation and differentiation, but also revealed variations in the degree of MSC differentiation based on donor-specific differences. Moreover, the enrichment of exosome-related genes among differentially expressed genes suggests a potential significant role for PDGF-BB in facilitating intercellular communication.

Bone development by Hedgehog and Wnt signaling, Runx2, and Sp7.

Hedgehog and canonical Wnt signaling pathways and the transcription factors Runx2 and Sp7 are essential for osteoblast differentiation. Ihh is necessary for the commitment of perichondrial mesenchymal cells to Runx2+ osteoprogenitors and for the formation of the bone collar and primary spongiosa. Runx2 is needed for osteoblast differentiation during both endochondral and intramembranous ossification. It regulates the commitment of mesenchymal cells to osteoblast-lineage cells and their proliferation by inducing the expression of Hedgehog, Fgf, Wnt, Pthlh signaling pathway genes, and Dlx5. The Runx2-induced expression of Fgfr2 and Fgfr3 is important for the proliferation of osteoblast-lineage cells. Runx2 induces Sp7 expression and Runx2+ osteoprogenitors become Runx2+Sp7+ preosteoblasts. Runx2, Sp7, and canonical Wnt signaling induce the differentiation of preosteoblasts into osteoblasts. Canonical Wnt signaling, but not Sp7, enhances the proliferation of osteoblast-lineage cells. In mature osteoblasts, Runx2 plays an important role in the expression of major bone matrix protein genes, including Col1a1, Col1a2, Spp1, Ibsp, and Bglap/Bglap2. The canonical Wnt signaling pathway is also crucial for bone formation by mature osteoblasts. Sp7 is needed for osteocytes to acquire a sufficient number of processes and a reduction in these processes results in osteocyte apoptosis and cortical porosity.

Erythropoietin regulates energy metabolism through EPO-EpoR-RUNX1 axis

Erythropoietin (EPO) plays a key role in energy metabolism, with EPO receptor (EpoR) expression in white adipose tissue (WAT) mediating its metabolic activity. Here, we show that male mice lacking EpoR in adipose tissue exhibit increased fat mass and susceptibility to diet-induced obesity. Our findings indicate that EpoR is present in WAT, brown adipose tissue, and skeletal muscle. Elevated EPO in male mice improves glucose tolerance and insulin sensitivity while reducing expression of lipogenic-associated genes in WAT, which is linked to an increase in transcription factor RUNX1 that directly inhibits lipogenic genes expression. EPO treatment in wild-type male mice decreases fat mass and lipogenic gene expression and increase in RUNX1 protein in adipose tissue which is not observed in adipose tissue EpoR ablation mice. EPO treatment decreases WAT ubiquitin ligase FBXW7 expression and increases RUNX1 stability, providing evidence that EPO regulates energy metabolism in male mice through the EPO-EpoR-RUNX1 axis.

VHL synthetic lethality screens uncover CBF-β as a negative regulator of STING.

Clear cell renal cell carcinoma (ccRCC) represents the most common form of kidney cancer and is typified by biallelic inactivation of the von Hippel-Lindau (VHL) tumour suppressor gene. Here, we undertake genome-wide CRISPR/Cas9 screening to reveal synthetic lethal interactors of VHL, and uncover that loss of Core Binding Factor β (CBF-β) causes cell death in VHL-null ccRCC cell lines and impairs tumour establishment and growth in vivo. This synthetic relationship is independent of the elevated activity of hypoxia inducible factors (HIFs) in VHL-null cells, but does involve the RUNX transcription factors that are known binding partners of CBF-β. Mechanistically, CBF-β loss leads to upregulation of type I interferon signalling, and we uncover a direct inhibitory role for CBF-β at the STING locus controlling Interferon Stimulated Gene expression. Targeting CBF-β in kidney cancer both selectively induces tumour cell lethality and promotes activation of type I interferon signalling.