Expression Of KLF4 Research Articles

MicroRNA-34a-5p regulates agouti-related peptide via krüppel-like factor 4 and is disrupted by bisphenol A in hypothalamic neurons

Obesity is a complex disease marked by increased adiposity and impaired metabolic function. While diet and lifestyle are primary causes, endocrine-disrupting chemicals (EDCs), such as bisphenol A (BPA), significantly contribute to obesity. BPA, found in plastic consumer products, accumulates in the hypothalamus and dysregulates energy homeostasis by disrupting the neuropeptide Y (NPY)/agouti-related peptide (AgRP) and pro-opiomelanocortin (POMC) neurons.However, the precise molecular mechanisms of how BPA disrupts neuropeptide expression remains unclear. We hypothesized that microRNAs (miRNAs), which regulate approximately 60% of the human protein-coding genome and are crucial for hypothalamic energy regulation, may mediate the effects of BPA on Agrp. Using the TargetScanMouse 8.0 and DIANA microT bioinformatics tools, we identified miR-501-5p as a potential miRNA that directly regulates Agrp and the miR-34 family as miRNAs that indirectly regulate Agrp through its transcription factor krüppel-like factor 4 (KLF4). We found that in an immortalized NPY/AgRP-expressing cell line, mHypoE-41, miR-501-5p unexpectedly upregulated Agrp, while miR-34a-5p reduced Klf4 and Agrp mRNA levels. Serum starvation reduced miR-34a-5p levels and elevated Agrp mRNA levels, suggesting a potential role in AgRP regulation. Inhibiting the miR-34a-5p interaction with the Klf4 3′UTR using a specific target site blocker prevented the downregulation of both Klf4 and Agrp, suggesting miR-34a-5p alters Agrp mRNA levels via regulation of KLF4. BPA treatment increased Agrp and Klf4 expression while simultaneously decreasing miR-34a-5p levels, indicating miR-34a-5p may play a role in BPA-mediated dysregulation of Agrp. Overall, this study highlights indirect miRNA-based regulation of Agrp, which can also be dysregulated by obesogens, such as BPA.

Downregulated KLF4, induced by m6A modification, aggravates intestinal barrier dysfunction in inflammatory bowel disease

BackgroundKrüppel-like factor 4 (KLF4), a transcription factor, is involved in various biological processes. However, the role of KLF4 in regulating the intestinal epithelial barrier (IEB) in inflammatory bowel disease (IBD) and its mechanism have not been extensively studied.MethodsKLF4 expression in IBD patients and colitis mice was analyzed using Gene Expression Omnibus(GEO) database, immunohistochemistry (IHC) and Western blot. The roles of KLF4 in IEB and colitis symptoms were verified in dextran sulfate sodium (DSS)-induced and 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis model mice using an adenovirus carrying KLF4 shRNA (shKLF4-Adv). Furthermore, the influence of KLF4 on trans-epithelium electrical resistance (TEER), paracellular permeability, apical junction complex (AJC) protein expression and apoptosis was assessed in vitro and in vivo. MeRIP and RIP assays were used to verify the effects of m6A modification on KLF4 expression.ResultsKLF4 expression was significantly decreased in IBD patients and was negatively associated with inflammatory features. KLF4 deletion aggravated colitis symptoms and IEB injuries by reducing AJC protein expression and increasing apoptosis in mice with colitis. Furthermore, KLF4 transcriptionally regulated the expression of AJC proteins and inhibited apoptosis by reducing cellular ROS levels and proinflammatory cytokine expression. Moreover, we observed that METTL3/ALKBH5/YTHDF2-mediated m6A modification led to a decrease in KLF4 expression in Caco-2 cells. In addition, APTO-253, an inducer of KLF4, exhibited a synergistic effect with mesalazine on IEB function.ConclusionsOur study demonstrated that KLF4 is a crucial regulator of IEB, suggesting that targeting KLF4 may be a promising therapeutic alternative for IBD.

Pericytes require physiological oxygen tension to maintain phenotypic fidelity

Pericytes function to maintain tissue homeostasis by regulating capillary blood flow and maintaining endothelial barrier function. Pericyte dysfunction is associated with various pathologies and has recently been found to aid cancer progression. Despite having critical functions in health and disease, pericytes remain an understudied population due to a lack of model systems which accurately reflect in vivo biology. In this study we developed a protocol to isolate and culture murine lung, brain, bone, and liver pericytes, that maintains their known phenotypes and functions. We demonstrate that pericytes, being inherently plastic, benefit from controlled oxygen tension culture conditions, aiding their expansion ex vivo. Primary pericytes grown in physiologically relevant oxygen tensions (10% O2 for lung; 5% O2 for brain, bone, and liver) also better retain pericyte phenotypes indicated by stable expression of characteristic transcriptional and protein markers. In functional tube formation assays, pericytes were observed to significantly associate with endothelial junctions. Importantly, we identified growth conditions that limit expression of the plasticity factor Klf4 to prevent spontaneous phenotypic switching in vitro. Additionally, we were able to induce pathological pericyte phenotypic switching in response to metastatic stimuli to accurately recapitulate in vivo biology. Here, we present a robust method for studying pericyte biology in both physiology and disease.

Exosomal miR-146a-5p Derived from HSCs Accelerates Sepsis-induced Liver Injury by Suppressing KLF-4.

This study aimed to investigate whether and how lipopolysaccharide (LPS) activated hepatic stellate cells (HSCs) regulate macrophage activity and to explore the impact of microRNAs (miRNAs) in exosomes from HSCs on this process. Mice subjected to LPS or cecal ligation and puncture (CLP) were used to explore sepsis-induced liver injury. Liver injury was evaluated using HE staining, and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured. LPS-Exo or N-LPS-Exo from HSCs were added to hepatic macrophages, and iNOS, IL-1β, and TNF-α expression was detected via Western blotting. miRNA microarray analysis and PCR were used to evaluate differentially expressed miRNAs between LPS-Exo and N-LPS-Exo. Target genes were screened using the TargetScan database and verified with luciferase assays and WB. Inflammation and macrophage activity were observed in vivo using HE and CD86 staining in mice injected with PKH67-labeled LPS-Exo or N-LPS-Exo. Sepsis-related liver injury activates hepatic stellate cells, which regulate macrophage activity through exosomes. Specifically, exosomal miR-146a-5p secreted by hepatic stellate cells targets KLF-4, regulating the macrophage inflammatory response through the JNK signaling pathway. Exosomes containing miRNA-146a-5p released from HSCs following LPS treatment may increase macrophage sensitivity to LPS and trigger an inflammatory response. Exosomal miR-146a-5p derived from HSCs accelerates sepsis-induced liver injury by suppressing KLF-4 expression.

KLF4 promotes cisplatin resistance by activating mTORC1 signaling in ovarian cancer

Ovarian cancer (OC) is a highly fatal gynecological malignancy worldwide, and cisplatin (CDDP) is commonly used as an initial chemotherapy treatment for OC. Nonetheless, most patients ultimately face recurrence because of resistance to cisplatin. Therefore, it is imperative to investigate the underlying mechanisms of drug resistance in OC. By analyzing differential gene expression using TCGA, GDSC, and GEO public databases, we discovered that increased KLF4 expression is strongly linked to chemotherapy resistance and unfavorable outcomes in OC. Subsequent validation through immunohistochemistry and western blotting confirmed the upregulated KLF4 expression in cisplatin-resistance OC cells lines and tissues. To investigate the function of KLF4, functional experiments were performed both in vitro and in vivo. We observed that knocking down KLF4 impaired cisplatin-resistance of OC. Further mechanism research based on RNA-seq and gene enrichment analysis revealed that interfering KLF4 suppressed the activation of mTORC1 pathway. Finally, rescue experiment demonstrated that using mTORC1 pathway inhibitor could attenuate the cisplatin resistance induced by the overexpression of KLF4. In conclusion, our research indicates that KLF4 promotes cisplatin resistance through the activation of mTORC1 signaling, and proposes that inhibiting KLF4 might serve as a viable therapeutic approach to overcoming drug resistance in ovarian cancer.

Initiation and maintenance of the pluripotent epiblast in pre-implantation human development is independent of NODAL signaling.

The human blastocyst contains the pluripotent epiblast from which human embryonic stem cells (hESCs) can be derived. ACTIVIN/NODAL signaling maintains expression of the transcription factor NANOG and invitro propagation of hESCs. It is unknown whether this reflects a functional requirement for epiblast development in human embryos. Here, we characterized NODAL signaling activity during pre-implantation human development. We showed that NANOG is an early molecular marker restricted to the nascent human pluripotent epiblast and was initiated prior to the onset of NODAL signaling. We further demonstrated that expression of pluripotency-associated transcription factors NANOG, SOX2, OCT4, and KLF17 were maintained in the epiblast in the absence of NODAL signaling activity. Genome-wide transcriptional analysis showed that NODAL signaling inhibition did not decrease NANOG transcription or impact the wider pluripotency-associated gene regulatory network. These data suggest differences in the signaling requirements regulating pluripotency in the pre-implantation human epiblast compared with existing hESC culture.

Human embryonic stem cell spheroids derived exosomal hsa_circ_0003258 sequestered dual targeting of miR-502-5p on KLF4/NF-κB and GALNT4/P53 to mitigate inflammation and apoptosis in hepatic ischemia reperfusion injury

Hepatic ischemia–reperfusion injury (HIRI) refers to excessive inflammation and metabolic dysfunction caused by liver surgery injuries. Exosomes (Exos) derived from stem cells (SCs) play an active role in mitigating HIRI, but the molecular mechanism remains largely elusive. In this study, we demonstrated that Exos derived from human embryonic stem cell spheroids (3D hESCs) could alleviate HIRI and restore liver functions by alleviating inflammation in M1 macrophages (Macs) and resisting apoptosis of hepatocytes. Regarding the molecular mechanism behind these therapeutic effects, we identified a specific circRNA, named hsa_circ_0003258, enriched in 3D hESC-Exos, plays a key role in the treatment of HIRI. The synergistic effect of hsa_circ_0003258 was identified not only to contribute to the suppression of inflammation but also concurrently inhibited hepatocyte apoptosis by using a series of in vitro assays, particularly utilizing the co-culture system of hepatocyte organoids (Hep-orgs) with M1 Macs. Conversely, silencing hsa_circ_0003258 had opposite effects. Specifically, hsa_circ_0003258 was confirmed to act as a sponge for miR-502-5p with dual targets on KLF4 of Macs and GALNT4 of hepatocytes, and jointly activating the expressions of KLF4 in Macs and GALNT4 in hepatocytes. This cascade ultimately mitigated Macs inflammation and hepatocytes apoptosis by simultaneously deactivating NF‐κB and P53 signaling pathways. In conclusion, we have illustrated that Exos derived from 3D hESCs possess the capability to attenuate HIRI. This effect is primarily achieved through the synergistic blockade of dual pathways involving hsa_circ_0003258/miR-502-5p/KLF4/NF‐κB and hsa_circ_0003258/miR-502-5p/GALNT4/P53 axes. Our findings provide insights into the precision treatment of HIRI through Exos based cell-free therapy.

MiR‑155 promotes an inflammatory response in HaCaT cells via the IRF2BP2/KLF2/NF‑κB pathway in psoriasis.

Psoriasis is a chronic inflammatory skin condition with numerous causes, including genetic, immunological and infectious factors. The course of psoriasis is long and recurrence is common; pathogenesis is not completely understood. However, there is an association between advancement of psoriasis and aberrant microRNA (miR or miRNA)‑155 expression. Through bioinformatics, the present study aimed to analyze the differentially expressed genes and miRNAs in psoriasis and its biological mechanism and function psoriatic inflammation. First of all, differentially expressed genes (DEGs) and miRNAs (DEMs) in patients with psoriasis were identified using GEO2R interactive web application. A psoriasis inflammatory model was established using lipopolysaccharide (LPS)‑treated HaCaT keratinocytes, which were transfected with miR‑155 mimic or inhibitor. Cell Counting Kit‑8 was used for the assessment of cell viability and proliferation, and changes in the cell cycle were examined using flow cytometry. ELISA and reverse transcription‑quantitative PCR (RT‑qPCR) were used to detect the expression levels of the inflammatory factors IL‑1β and IL‑6. The dual‑luciferase reporter assay was used to verify the targeting association between miR‑155‑5p and IFN regulatory factor 2 binding protein 2 (IRF2BP2). To verify the targeting association of miR‑155 and the IRF2BP2/kruppel‑like factor 2 (KLF2)/NF‑κB signaling pathway, expression levels of IRF2BP2, KLF2 and p65 were identified by RT‑qPCR and western blotting. IRF2BP2 levels were also confirmed by immunofluorescence, in conjunction with bioinformatics database analysis. Overexpression of miR‑155 inhibited proliferation of HaCaT cells and increased the number of cells in S phase and decreasing number of cells in G1 and G2 phase. In the LPS‑induced inflammatory state, miR‑155 overexpression heightened the inflammatory response of HaCaT cells while inhibition of miR‑155 lessened it. Suppression of inflammatory cytokine expression by miR‑155‑5p inhibitor was reversed by knockdown of IRF2BP2. miR‑155 was shown to interact with IRF2BP2 to negatively regulate its expression, leading to decreased KLF2 expression and increased p65 expression and secretion of inflammatory factors, intensifying the inflammatory response of HaCaT cells. Therefore, miR‑155 may contribute to development of psoriasis by inducing tissue and cell damage by increasing the inflammatory response of HaCaT cells via the IRF2BP2/KLF2/NF‑κB pathway. In conclusion, the results of the present study offer novel perspectives on the role of miR‑155 in the onset and progression of psoriasis.

Downregulation of Krüppel-like factor 15 expression delays endochondral bone ossification during fracture healing

ObjectiveThe role of Krüppel-like zinc finger transcription factor 15 (KLF15) in endochondral ossification during fracture healing remains unexplored. In this study, we aimed to elucidate the impact of KLF15 in a mouse model of tibial transverse fracture. MethodsWe created tamoxifen-inducible, cartilage-specific KLF15 knockout mice (KLF15 KO). KLF15 fl/fl Col2-CreERT mice from the same litters as the KLF15 KO mice, but not treated with 4-hydroxytamoxifen, were used as controls (CT). At 10 weeks, male KLF15 KO and CT mice underwent tibial fracture followed by intramedullary nailing. Both groups were administered tamoxifen at days 0, 3, and 7 after surgery. The tibiae were harvested on post-surgery days 7, 10, and 14 for radiological assessment using micro-computed tomography. Histological staining (Safranin-O) and immunohistochemistry for KLF15, SOX9, Indian hedgehog (IHH), RUNX2, and Osterix were performed. Additionally, cartilage from mouse fetus was cultured for qRT-PCR and western blot analyses of KLF15, SOX9, IHH, Col2, RUNX2, Osterix, TGF-β, SMAD3, and phosphor-SMAD3. ResultsThe radiological assessment revealed that immature callus formation was delayed in KLF15 KO, compared with that in CT, peaking on day 14 compared with that on day 10 in CT. KLF15 KO mice exhibited delayed fracture healing and reduced Safranin-O staining at days 7 and 10 post-surgery. The ratio of cells positive for KLF15 and SOX9 was significantly lower in KLF15 KO than in CT, whereas the ratios for IHH, RUNX2, and Osterix showed no significant difference. RT-PCR revealed reduced expression of KLF15, SOX9, and COL2, with no significant changes in IHH, Osterix, RUNX2, TGF-β, and SMAD3. Western blot analysis indicated decreased SMAD3 phosphorylation in KLF15 KO mice. ConclusionKLF15 regulates SOX9 via the TGF-β-SMAD3-SOX9 pathway, independent of IHH, in endochondral ossification. The KLF15 deficiency decreases SOX9 expression through reduced SMAD3 phosphorylation, subsequently delaying fracture healing.

HDAC6 promotes inflammation in lupus nephritis mice by regulating transcription factors MAFF and KLF5 in renal fibrosis

Aim This study explored the effect and mechanism of MAFF and HDAC6 on renal fibrosis and inflammation in lupus nephritis (LN). Methods IL-33 treated renal epithelial cells and MRL/lpr mice were respectively used for in vitro and in vivo experiments. The expressions of HDAC6, MAFF, and KLF5 were measured in cells and renal tissues. Before and after cell transfection, the morphological changes in renal tissues were observed using Hematoxylin and eosin (H&E) and Masson staining. The proteinuria, serum creatinine (SCr), blood urea nitrogen (BUN), and double-stranded DNA (dsDNA) levels were detected by biochemical analysis. The expressions of fibrosis and inflammation related proteins (including α-SMA, Vimentin, IL-1β, IL-6, and TNF-α), p65, and iNOS were also detected. The relationship among MAFF, HDAC6, and KLF5 was determined by chromatin immunoprecipitation and dual luciferase reporter gene assay. Results Renal tissues and cell models had elevated expressions of HDAC6 and KLF5, and decreased MAFF expression. HDAC6 suppression or MAFF overexpression led to suppression of proteinuria, SCr, BUN, and dsDNA levels, as well as attenuation of inflammatory infiltration and collagen deposition. HDAC6 can suppress MAFF expression via deacetylation to abolish its suppression of KLF5 expression, thus increasing KLF5 expression. In vivo and in vitro experiments showed the suppressive effect of HDAC6 suppression on renal fibrosis and inflammation can be abolished by KLF5 overexpression. Conclusion HDAC6 suppresses MAFF expression via deacetylation to elevate KLF5 expression, which consequently enhances fibrosis and inflammatory response in LN.

Renoprotective effect of liraglutide on diabetic nephropathy by modulation of Krüppel-like transcription factor 5 expression in rats.

Diabetic nephropathy (DN) is a serious consequence of diabetes that can develop through the lysophosphatidic acid axis. The purpose of this study was to determine whether the antidiabetic drug liraglutide can slow the development of diabetic kidney damage by altering the lysophosphatidic acid axis via KLF5. Wistar albino rats were divided into nondiabetic and diabetic rats (resulting from an intraperitoneal streptozotocin dose of 30mg/kg and a high-fat diet). These rats were further divided into four groups: nondiabetic control, liraglutide-treated nondiabetic, diabetic control, and liraglutide-treated diabetic. The nondiabetic and diabetic control groups received normal saline for 42 days, while the liraglutide-treated nondiabetic and diabetic groups received normal saline for 21 days, followed by a subcutaneous dose of liraglutide (200 μg/kg/day) for 21 days. Subsequently, serum levels of DN biomarkers were evaluated, and kidney tissues were histologically examined. The protein expression of PCNA, autotaxin, and KLF5 was detected. Liraglutide treatment in diabetic rats decreased DN biomarkers, histological abnormalities in kidney tissues, and the protein expression of PCNA, autotaxin, and KLF5. Liraglutide can slow the progression of DN by modulating KLF5-related lysophosphatidic acid axis. Thus, liraglutide may be an effective treatment for preventing or mitigating diabetes-related kidney damage.

The protective effects of annexin A1 against oxidized-LDL-induced monocytes adhesion to endothelial cells: implication in atherosclerosis.

Oxidized low-density lipoprotein (ox-LDL)-associated endothelial dysfunction is a critical factor in the initiation and progression of Atherosclerosis (AS). Annexin A1 is an important member of the annexin family. Despite its wide range of biological functions across various tissues and cells, the role of Annexin A1 in AS remains largely unexplored. In this study, we demonstrate that Annexin A1 treatment effectively reduced the expression of LOX-1 at both the mRNA and protein levels in HUVECs exposed to ox-LDL. Annexin A1 also ameliorated oxidative stress (OS) by decreasing mitochondrial ROS levels and restoring reduced GSH levels. Moreover, Annexin A1 decreased the expression of pro-inflammatory cytokines, including IL-6 and MCP-1. Importantly, Annexin A1 inhibited ox-LDL-induced expressions of the endothelial adhesion molecules, such as E-selectin and VCAM-1 in HUVECs, which leads to reduced attachment of THP-1 monocytes to HUVECs. Mechanically, we found that Annexin A1 reversed the expression of KLF2 against ox-LDL mediated by the PI3K/Akt axis. Notably, the silencing of KLF2 abrogated the protective effects of Annexin A1 on E-selectin and VCAM-1 expression and the attachment of THP-1 monocytes to HUVECs. Our findings suggest that Annexin A1 is a potential therapeutic agent for atherosclerosis, offering a novel approach to mitigate endothelial dysfunction and inflammation.

Pterosin B improves cognitive dysfunction by promoting microglia M1/M2 polarization through inhibiting Klf5/Parp14 pathway

BackgroundPterosin B (PB) exhibits strong neuroprotective effects in vitro, but its therapeutic effect and underlying mechanism on Alzheimer's disease (AD) remain elusive. PurposeThis study aimed to investigate the anti-AD effect and mechanism of PB. Study designThe therapeutic effect and mechanism of PB were investigated in APP/PS1 mice and lipopolysaccharide (LPS)-induced BV-2 cells. MethodsAfter 8 weeks of oral administration of PB or donepezil, the cognitive function was assessed using behavioral tests. Pathological damage was evaluated using histological analysis and immunohistochemical staining. Flow cytometry was applied to detect M1/M2 polarization. The expression levels of glycolysis- and oxidative phosphorylation-related proteins as well as enzyme activities were determined using Western blot and biochemical kits, respectively. The levels of inflammatory cytokines and Kruppel-like factor 5 (Klf5) were measured using enzyme-linked immunosorbent assay. AD biomarkers in serum were analyzed using single-molecular array. RNA sequencing identified the downstream molecules of Klf5, and interaction was evaluated using dual-luciferase reporter assay. ResultsOur findings demonstrated that PB effectively ameliorated cognitive impairment and reduced pathological damage in APP/PS1 mice. Furthermore, PB facilitated the transition of the phenotype of LPS-induced BV-2 cells from M1 to M2 by modulating metabolic reprogramming. Additionally, Klf5 had high expression levels in the serum of patients with AD, which strongly correlated with cognitive performance and AD biomarkers. PB downregulated Klf5 expression both in vitro and in vivo. Subsequently, poly-ADP ribosyl polymerase 14 (Parp14) was identified as a downstream molecule of Klf5 involved in regulating metabolic reprogramming, and PB regulated microglia M1/M2 polarization by inhibiting the Klf5/Parp14 pathway. ConclusionThe findings suggested that PB ameliorated cognitive dysfunction in AD by modulating microglia M1/M2 polarization via inhibiting Klf5/Parp14 pathway.

Low Intraocular Pressure Induces Fibrotic Changes in the Trabecular Meshwork and Schlemm's Canal of Sprague Dawley Rats.

Continuous artificial aqueous humor drainage in the eyes of patients with glaucoma undergoing trabeculectomy likely exerts abnormal shear stress. However, it remains unknown how changes in intraocular pressure (IOP) can affect aqueous humor outflow (AHO). Here, we induced and maintained low intraocular pressure (L-IOP) in healthy Sprague Dawley (SD) rats by puncturing their eyes using a tube (200-µm diameter) for 2 weeks. After the rats were euthanized, their eyes were removed, fixed, embedded, stained, and scanned to analyze the physiological and pathological changes in the trabecular meshwork (TM) and Schlemm's canal (SC). We measured SC parameters using ImageJ software and assessed the expression of various markers related to flow shear stress (KLF4), fibrosis (TGF-β1, TGF-β2, α-SMA, pSmad1/5, pSmad2/3, and fibronectin), cytoskeleton (integrin β1 and F-actin), diastolic function (nitric oxide synthase and endothelial nitric oxide synthase [eNOS]), apoptosis (cleaved caspase-3), and proliferation (Ki-67) using immunofluorescence or immunohistochemistry. L-IOP eyes showed a larger SC area, higher eNOS expression, and lower KLF4 and F-actin expression in the TM and SC (both P < 0.05) than control eyes. The aqueous humor of L-IOP eyes had a higher abundance of fibrotic proteins and apoptotic cells than that of control eyes, with significantly higher TGF-β1, α-SMA, fibronectin, and cleaved caspase-3 expression (all P < 0.05). In conclusion, a persistence of L-IOP for 2 weeks may contribute to fibrosis in the TM and SC and might be detrimental to conventional AHO in SD rat eyes. Clinicians should consider that aberrant shear force induced by aqueous humor fluctuation may damage AHO outflow channel when treating patients.

TRβ activation confers AT2-to-AT1 cell differentiation and anti-fibrosis during lung repair via KLF2 and CEBPA

Aberrant repair underlies the pathogenesis of pulmonary fibrosis while effective strategies to convert fibrosis to normal regeneration are scarce. Here, we found that thyroid hormone is decreased in multiple models of lung injury but is essential for lung regeneration. Moreover, thyroid hormone receptor α (TRα) promotes cell proliferation, while TRβ fuels cell maturation in lung regeneration. Using a specific TRβ agonist, sobetirome, we demonstrate that the anti-fibrotic effects of thyroid hormone mainly rely on TRβ in mice. Cellularly, TRβ activation enhances alveolar type-2 (AT2) cell differentiation into AT1 cell and constrains AT2 cell hyperplasia. Molecularly, TRβ activation directly regulates the expression of KLF2 and CEBPA, both of which further synergistically drive the differentiation program of AT1 cells and benefit regeneration and anti-fibrosis. Our findings elucidate the modulation function of the TRβ-KLF2/CEBPA axis on AT2 cell fate and provide a potential treatment strategy to facilitate lung regeneration and anti-fibrosis.

KLF15 suppresses stemness of pancreatic cancer by decreasing USP21-mediated Nanog stability

The existence of cancer stem cells (CSCs) in pancreatic ductal adenocarcinoma (PDAC) is considered to be the key factor for metastasis and chemoresistance. Thus, novel therapeutic strategies for eradicating CSCs are urgently needed. Here we aimed to explore the role of KLF15 in stemness and the feasibility of using KLF15 to inhibit CSCs and improve chemotherapy sensitivity in PDAC. In this study, we report that KLF15 is negatively associated with poor survival and advanced pathological staging of PDAC. Moreover, tumorous KLF15 suppresses the stemness of PDAC by promoting the degradation of Nanog, and KLF15 directly interacts with Nanog, inhibiting interaction between Nanog with USP21. We also demonstrate that the KLF15/Nanog complex inhibit the stemness in vivo and in PDX cells. Tazemetostat suppresses stemness and sensitizes PDAC cells to gemcitabine by promoting KLF15 expression in PDAC. In summary, the findings of our study confirm the value of KLF15 level in diagnosis and prognosis of PDAC, it is the first time to explore the inhibition role of KLF15 in stemness of PDAC and the regulation mechanism of Nanog, contributing to provide a new therapeutic strategy that using Tazemetostat sensitizes PDAC cells to gemcitabine by promoting KLF15 expression for PDAC.Graphical

Role of KLF4 and SIAT7A interaction accelerates myocardial hypertrophy induced by Ang II.

Sialylation catalysed by sialyltransferase 7A (SIAT7A) plays a role in the development of cardiac hypertrophy. However, the regulatory mechanisms upstream of SIAT7A in this context remain poorly elucidated. Previous study demonstrated that KLF4 activates the SIAT7A gene in ischemic myocardium by binding to its promoter region. Nevertheless, the potential involvement of KLF4 in regulating SIAT7A expression in Ang II-induced hypertrophic cardiomyocytes remains uncertain. This study seeks to deepen the underlying mechanisms of the KLF4 and SIAT7A interaction in the progression of Ang II-induced cardiac hypertrophy. The results showed a concurrent increase in SIAT7A and KLF4 levels in hypertrophic myocardium of essential hypertension patients and in hypertrophic cardiomyocytes stimulated by Ang II. Invitro experiments revealed that reducing KLF4 levels led to a decrease in both SIAT7A synthesis and Sialyl-Tn antigen expression, consequently inhibiting Ang II-induced cardiomyocyte hypertrophy. Intriguingly, reducing SIAT7A levels also resulted in decreased KLF4 expression and suppression cardiomyocyte hypertrophy. Consistent with this, elevating SIAT7A levels increased KLF4 expression and exacerbated cardiomyocyte hypertrophy in both invivo and invitro experiments. Additionally, a time-course analysis indicated that KLF4 expression preceded that of SIAT7A. Luciferase reporter assays further confirmed that modulating SIAT7A levels directly influenced the transcriptional activity of KLF4 in cardiomyocytes. In summary, KLF4 expression is upregulated in cardiomyocytes treated with Ang II, which subsequently induces the expression of SIAT7A. The elevated levels of SIAT7A, in turn, enhance the transcription of KLF4. These findings suggest a positive feedback loop between KLF4 and SIAT7A-Sialyl-Tn, ultimately promoting Ang II-induced cardiac hypertrophy.

Single-cell and spatial transcriptomics reveal apelin/APJ pathway's role in microvessel formation and tumour progression in hepatocellular carcinoma.

The apelin receptor (APJ) is a key player in tumour angiogenesis, but its role in hepatocellular carcinoma (HCC) remains unclear. This study aims to elucidate the function of the apelin/APJ pathway in HCC using a multi-omics approach and identify potential therapeutic biomarkers. Differentially expressed genes related to the apelin/APJ axis were identified from bulk transcriptomics to reveal HCC-associated disparities. Single-cell and spatial transcriptomics were used to localize and analyse the function of these genes. Machine learning models were constructed to predict outcomes based on apelin/APJ expression, and experimental validation was conducted to explore the pathway's impact on HCC angiogenesis. Single cell analysis revealed an overexpression of APJ/Aplin in the endothelium. The stemness of endothelial cell (EC) with high apelin/APJ was enhanced, as well as the expression of TGFb, oxidative stresses and PI3K/AKT pathway genes. Spatial transcriptomics confirmed that EC populations with high APJ scores were enriched within the tumour. Machine learning models showed high prognostic accuracy. High APJ expression was linked to worse outcomes (p = 0.001), and AUC values were high (1 year, 3 year, 5 year) (0.95, 0.97, 0.98). Immune suppression and non-responsiveness of immune therapy were also seen in high-risk groups. The experimental validation showed that silencing apelin reduced angiogenesis (p < 0.05), endothelial proliferation, decreased expression of ANG2, KLF2, VEGFA and lower ERK1/2 phosphorylation. Apelin may serve as a potential therapeutic target in HCC, given its role in promoting tumour angiogenesis and poor patient outcomes.

A suboptimal OCT4-SOX2 binding site facilitates the naïve-state specific function of a Klf4 enhancer.

Enhancers have critical functions in the precise, spatiotemporal control of transcription during development. It is thought that enhancer grammar, or the characteristics and arrangements of transcription factor binding sites, underlie the specific functions of developmental enhancers. In this study, we sought to identify grammatical constraints that direct enhancer activity in the naïve state of pluripotency, focusing on the enhancers for the naïve-state specific gene, Klf4. Using a combination of biochemical tests, reporter assays, and endogenous mutations in mouse embryonic stem cells, we have studied the binding sites for the transcription factors OCT4 and SOX2. We have found that the three Klf4 enhancers contain suboptimal OCT4-SOX2 composite binding sites. Substitution with a high-affinity OCT4-SOX2 binding site in Klf4 enhancer E2 rescued enhancer function and Klf4 expression upon loss of the ESRRB and STAT3 binding sites. We also observed that the low-affinity of the OCT4-SOX2 binding site is crucial to drive the naïve-state specific activities of Klf4 enhancer E2. Altogether, our work suggests that the affinity of OCT4-SOX2 binding sites could facilitate enhancer functions in specific states of pluripotency.

Disturbed function of TBL1X has a differential effect on T3-regulated gene expression in two human liver cell models.

Mutations in TBL1X, part of the NCOR1/SMRT corepressor complex, were identified in patients with hereditary X-linked central congenital hypothyroidism and associated hearing loss. The role of TBL1X in thyroid hormone (TH) action, however, is incompletely understood. The aim of the present study was to investigate the role of TBL1X on T3-regulated gene expression in two human liver cell models. A human hepatoma cell line (HepG2) wherein TBL1X was downregulated using siRNAs, and human-induced pluripotent stem cell-derived hepatocytes (iHeps) generated from individuals with a TBL1X N365Y mutation. Both cell types were treated with increasing concentrations of T3. The expression of T3-regulated genes was measured by qPCR. KLF9, CPT1A, and PCK1 mRNA expression were higher upon T3 stimulation in the HepG2 cells with decreased TBL1X expression compared to controls, while DIO1 mRNA expression was lower. Hemizygous TBL1X N365Y iHeps exhibited decreased expression of CPT1A, G6PC1, PCK1, FBP1, and ELOVL2 compared to cells with the heterozygous TBL1X N365Y allele, but KLF9 and HMGCS2 expression was unaltered. Downregulation of TBL1X in HepG2 cells and the TBL1X N365Y variant in iHeps have differential effects on T3-regulated gene expression. This suggests that TBL1X may play a gene context role in TH action.