BTG/Tob family members Tob1 and Tob2 inhibit proliferation of mouse embryonic stem cells via Id3 mRNA degradation

Whole transcriptome analysis in oviduct provides insight into microRNAs and ceRNA regulative networks that targeted reproduction of goat (Capra hircus)

BACKGROUND

Reproduction traits are crucial for livestock breeding and represent key economic indicators in the domestic goat (Capra hircus) industry. The oviduct, a critical organ in female mammals, plays a pivotal role in several reproductive processes; however, its molecular mechanisms remain largely unknown. Non-coding RNA and mRNAs are essential regulatory elements in reproductive processes; yet their specific roles and regulatory networks in goat oviducts remain unclear.

RESULTS

In this study, we conducted small RNA sequencing of the oviduct in high- and low-fecundity goats during the follicular (FH and FL groups, n = 10) and luteal (LH and LL groups, n = 10) phase, profiling 20 tissue samples. Combinatorial whole-transcriptome expression profiles were applied to the same samples to uncover the competitive endogenous RNA (ceRNA) regulation network associated with goat fecundity. RT-qPCR was employed to validate the miRNA profiling results, and ceRNA regulatory networks were analyzed through luciferase assay. Gene set enrichment analysis (GSEA) confirmed that the cytokine-cytokine receptor interaction and TGF-β signaling pathway, both related to embryonic development, were enriched in DEM target genes. Additionally, miR-328-3p, a core miRNA, targets SMAD3 and BOP1, which are involved in the negative regulation of cell growth and embryonic development. TOB1 and TOB2, targeted by miR-204-3p, regulate cell proliferation via the protein kinase C-activating G-protein coupled receptor signaling pathway. Analyses of ceRNA regulatory networks revealed that LNC_005981 - miR-328-3p - SMAD3 and circ_0021923 - miR-204-3p - DOT1L may affect goats' reproduction, findings that were validated using luciferase assay.

CONCLUSION

Analysis of whole-transcriptome profiling of goat oviducts identified several key miRNAs and ceRNAs that may regulate oocyte maturation, embryo development, and the interactions between the oviduct and gametes/early embryos, providing insights into the molecular mechanisms of reproductive regulatory networks.

Altered Cell Clusters and Upregulated Aqp1 in Connexin 50 Knockout Lens Epithelium

Purpose

To characterize the heterogeneity and cell clusters of postnatal lens epithelial cells (LECs) and to investigate the downstream targets of connexin 50 (Cx50) in the regulation of lens homeostasis and lens growth. To determine differentially expressed genes (DEGs) in the connexin 50 knockout (Cx50KO) lens epithelial cells that shed light on novel mechanism underlying the cataract and small size of the Cx50KO lenses.

Methods

Single-cell RNA sequencing (scRNA-seq) of lens epithelial cells isolated from one-month-old Cx50KO and wild-type (WT) mice were performed. Differentially expressed genes were identified, and selected DEGs were further studied by quantitative real-time PCR (RT-qPCR) analysis and Western blot analysis.

Results

The expression profiles of several thousand genes were identified by scRNA-seq data analysis. In comparison to the WT control, many DEGs were identified in the Cx50KO lens epithelial cells, including growth regulating transcriptional factors and genes encoding water channels. Significantly upregulated aquaporin 1 (Aqp1) gene expression was confirmed by RT-qPCR, and upregulated AQP1 protein expression was confirmed by Western blot analysis and immunostaining both in vivo and in vitro.

Conclusions

Lens epithelial cells exhibit an intrinsic heterogeneity of different cell clusters in regulating lens homeostasis and lens growth. Upregulated Aqp1 in Cx50KO lens epithelial cells suggests that both connexin 50 and AQP1 likely play important roles in regulating water homeostasis in lens epithelial cells.

Deciphering the molecular nexus of BTG2 in periodontitis and diabetic kidney disease

OBJECTIVE

To investigate the role of BTG2 in periodontitis and diabetic kidney disease (DKD) and its potential underlying mechanism.

METHODS

Gene expression data for periodontitis and DKD were acquired from the Gene Expression Omnibus (GEO) database. Differential expression analysis identified co-expressed genes between these conditions. The Nephroseq V5 online nephropathy database validated the role of these genes in DKD. Pearson correlation analysis identified genes associated with our target gene. We employed Gene Set Enrichment Analysis (GSEA) and Protein-Protein Interaction (PPI) networks to elucidate potential mechanisms. Expression levels of BTG2 mRNA were examined using quantitative polymerase Chain Reaction (qPCR) and immunofluorescence assays. Western blotting quantified proteins involved in epithelial-to-mesenchymal transition (EMT), apoptosis, mTORC1 signaling, and autophagy. Additionally, wound healing and flow cytometric apoptosis assays evaluated podocyte migration and apoptosis, respectively.

RESULTS

Analysis of GEO database data revealed BTG2 as a commonly differentially expressed gene in both DKD and periodontitis. BTG2 expression was reduced in DKD compared to normal conditions and correlated with proteinuria. GSEA indicated enrichment of BTG2 in the EMT and mTORC1 signaling pathways. The PPI network highlighted BTG2's relevance to S100A9, S100A12, and FPR1. Immunofluorescence assays demonstrated significantly lower BTG2 expression in podocytes under high glucose (HG) conditions. Reduced BTG2 expression in HG-treated podocytes led to increased levels of EMT markers (α-SMA, vimentin) and the apoptotic protein Bim, alongside a decrease in nephrin. Lower BTG2 levels were associated with increased podocyte mobility and apoptosis, as well as elevated RPS6KB1 and mTOR levels, but reduced autophagy marker LC3.

CONCLUSION

Our findings suggest that BTG2 is a crucial intermediary gene linking DKD and periodontitis. Modulating autophagy via inhibition of the mTORC1 signaling pathway, and consequently suppressing EMT, may be pivotal in the interplay between periodontitis and DKD.

SKGQA, a Peptide Derived from the ANA/BTG3 Protein, Cleaves Amyloid-β with Proteolytic Activity

Despite the extensive research conducted on Alzheimer's disease (AD) over the years, no effective drug for AD treatment has been found. Therefore, the development of new drugs for the treatment of AD is of the utmost importance. We recently reported the proteolytic activities of JAL-TA9 (YKGSGFRMI) and ANA-TA9 (SKGQAYRMA), synthetic peptides of nine amino acids each, derived from the Box A region of Tob1 and ANA/BTG3 proteins, respectively. Furthermore, two components of ANA-TA9, ANA-YA4 (YRMI) at the C-terminus end and ANA-SA5 (SKGQA) at the N-terminus end of ANA-TA9, exhibited proteolytic activity against amyloid-β (Aβ) fragment peptides. In this study, we identified the active center of ANA-SA5 using AEBSF, a serine protease inhibitor, and a peptide in which the Ser residue of ANA-SA5 was replaced with Leu. In addition, we demonstrate the proteolytic activity of ANA-SA5 against the soluble form Aβ42 (a-Aβ42) and solid insoluble form s-Aβ42. Furthermore, ANA-SA5 was not cytotoxic to A549 cells. These results indicate that ANA-SA5 is a promising Catalytide and a potential candidate for the development of new peptide drugs targeting Aβ42 for AD treatment.

Differential expression of TOB/BTG family members in patients with plaque psoriasis: cross-sectional study

TOB/BTG is a family of antiproliferative proteins that play an important role in the regulation of immune responses, acting as lymphocyte activators and macrophage-mediated cytotoxicity. No previous studies have explored their role in patients with psoriasis. The aim of this study was to characterize the expression of TOB/BTG family and their co-localization in skin from patients with psoriasis. This is an exploratory, observational, and cross-sectional study that included 24 plaque psoriasis patients and 15 controls. Gene expression of TOB/BTG family was determinate by RT-PCR. Protein products of TOB/BTG were evaluated by immunohistochemistry and compared with control skin tissues. Holm-Sidak's multiple comparisons test was performed. TOB/BTG family mRNA levels and protein expression were significantly decreased in psoriatic skin tissue compared to non-inflammatory control skin tissue. Double-positive cell TOB1/2, BTG1,2 and BTG4/CD16 expressions were found in normal control skin tissues through epidermis and dermis (p < 0.001) and lesser percentage in patients with mild, almost absent in moderate-severe plaque psoriasis. This is the first report of the TOB/BTG family gene and protein expression in skin tissues by a CD16 + subpopulation in plaque psoriasis. TOB/BTG family protein might represent a new therapeutic target among immune-mediated inflammatory diseases.

Monocyte-derived alveolar macrophages are key drivers of smoke-induced lung inflammation and tissue remodeling

Smoking is a leading risk factor of chronic obstructive pulmonary disease (COPD), that is characterized by chronic lung inflammation, tissue remodeling and emphysema. Although inflammation is critical to COPD pathogenesis, the cellular and molecular basis underlying smoking-induced lung inflammation and pathology remains unclear. Using murine smoke models and single-cell RNA-sequencing, we show that smoking establishes a self-amplifying inflammatory loop characterized by an influx of molecularly heterogeneous neutrophil subsets and excessive recruitment of monocyte-derived alveolar macrophages (MoAM). In contrast to tissue-resident AM, MoAM are absent in homeostasis and characterized by a pro-inflammatory gene signature. Moreover, MoAM represent 46% of AM in emphysematous mice and express markers causally linked to emphysema. We also demonstrate the presence of pro-inflammatory and tissue remodeling associated MoAM orthologs in humans that are significantly increased in emphysematous COPD patients. Inhibition of the IRAK4 kinase depletes a rare inflammatory neutrophil subset, diminishes MoAM recruitment, and alleviates inflammation in the lung of cigarette smoke-exposed mice. This study extends our understanding of the molecular signaling circuits and cellular dynamics in smoking-induced lung inflammation and pathology, highlights the functional consequence of monocyte and neutrophil recruitment, identifies MoAM as key drivers of the inflammatory process, and supports their contribution to pathological tissue remodeling.

Functional mechanism of miR-92b-3p in osteogenic differentiation of fibroblasts in patients with ankylosing spondylitis via the TOB1/BMP/Smad pathway

BACKGROUND

Ankylosing spondylitis (AS) is a chronic inflammatory arthritis. Upregulation of microRNA (miR)-92b-3p is associated with enhanced osteoblastic differentiation. The current study sought to investigate the functional mechanism of miR-92b-3p in osteogenic differentiation of AS fibroblasts.

METHODS

First, fibroblasts were isolated from AS and non-AS patients and cultured. Next, cell morphology was observed, cell proliferation was assessed and the vimentin expression pattern was determined. Alkaline phosphatase (ALP) activity and levels of osteogenic markers RUNX2, OPN, OSX, and COL I were additionally measured, followed by determination of miR-92b-3p and TOB1 levels. The binding site of miR-92b-3p and TOB1 was predicted, and their target relationship was validated. Lastly, miR-92b-3p inhibitor, si-TOB1, and the BMP/Smad signaling pathway inhibitor LDN193189 were delivered into AS fibroblasts to evaluate the osteogenic differentiation of AS fibroblasts and the activation of the BMP/Smad pathway.

RESULTS

miR-92b-3p was highly expressed in AS fibroblasts. AS fibroblasts showed enhanced osteogenic differentiation and proliferation, while inhibition of miR-92b-3p suppressed osteogenic differentiation and proliferation of AS fibroblasts. miR-92b-3p targeted TOB1, and TOB1 was poorly expressed in AS fibroblasts. The concurrent downregulation of TOB1 and inhibition of miR-92b-3p elevated the levels of RUNX2, OPN, OSX, and COL I and ALP activity and further enhanced the proliferation of AS fibroblasts. The BMP/Smad pathway was activated in AS fibroblasts. Silencing miR-92b-3p could inhibit the activation of the BMP/Smad pathway by upregulating TOB1. Inhibition of the BMP/Smad pathway reduced the number of calcified nodules and hindered the osteogenic differentiation and proliferation of AS fibroblasts.

CONCLUSION

Our findings highlighted that silencing miR-92b-3p inhibited the osteogenic differentiation and proliferation of AS fibroblasts by upregulation of TOB1 and inhibition of the BMP/Smad pathway.

Five-mer peptides prevent short-term spatial memory deficits in Aβ25-35-induced Alzheimer's model mouse by suppressing Aβ25-35 aggregation and resolving its aggregate form

BACKGROUND

The development of drugs for Alzheimer's disease (AD), which is related to the misfolding and aggregation of amyloid-β (Aβ), is high in demand due to the growing number of AD patients. In this study, we screened 22 kinds of 5-mer synthetic peptides derived from the Box A region of Tob1 protein to find a peptide effective against Aβ aggregation.

METHODS

A Thioflavin T (ThT) assay was performed to evaluate aggregation and screen aggregation inhibitors. Male ICR mice (6 weeks old) were administered saline, 9 nmol Aβ25-35, or a mixture of 9 nmol Aβ25-35 and 9 nmol GSGFK in the right lateral ventricle. Short-term spatial memory was assessed through Y-maze. Microglia cells (BV-)2 cells were plated on 24-well plates (4 × 10⁴ cells/well) and incubated for 48 h, and then, the cells were treated with 0.01, 0.05, 0.1, 0.2, or 0.5 mM GSGFK. After incubation for 24 h, bead uptake was evaluated using a laser confocal microscope and Cytation 5.

RESULTS

We found two kinds of peptides, GSGNR and GSGFK, that were not only suppressed by aggregation of Aβ25-35 but also resolved the aggregated Aβ25-35. Results obtained from the Y-maze test on an Aβ25-35-induced AD model mouse indicated that GSGFK prevents the deficits in short-term memory induced by Aβ25-35. The effect of GSGFK on phagocytosis in BV-2 cells proved that GSGFK activates the phagocytic ability of microglia.

CONCLUSIONS

In conclusion, 5-mer peptides prevent short-term memory deficit in Aβ25-35 induced AD model mouse by reducing the aggregated Aβ25-35. They may also upregulate the phagocytic ability of microglia, which makes 5-mer peptides suitable candidates as therapeutic drugs against AD.

miR-378a-3p promotes renal cell carcinoma proliferation, migration, and invasion by targeting TOB2

PURPOSE

Renal cell carcinoma (RCC) is one of the most common malignant tumors of the urinary system, which has high metastasis. MicroRNAs (miRNAs) have been reported to participate in RCC progression. The present study aimed to understand the biological role and mechanism of miR-378a-3p in RCC.

METHODS

RT-qPCR assay was used to assess miR-378a-3p and transducer of ERBB2 (TOB2) expression in RCC tissues and cell lines. CCK-8, clone formation, scratch, and transwell assays were carried out to evaluate cell proliferation, migration, and invasion. Furthermore, the target genes of miR-378a-3p were predicted by the online bioinformatics databases. Dual-luciferase reporter assay was used to validate the relationship between miR-378a-3p and TOB2.

RESULTS

miR-378a-3p was highly expressed in RCC tissues and RCC cell lines. Besides, miR-378a-3p accelerated the progression of RCC by mediating cell proliferation, migration and invasion. More importantly, TOB2 was confirmed as a potential target gene of miR-378a-3p. The results of loss-of-function experiments showed that inhibition of TOB2 reversed the inhibitory roles of miR-378a-3p inhibitor on RCC progression.

CONCLUSIONS

miR-378a-3p promoted cell proliferation, migration and invasion through regulating TOB2 in RCC, which indicated a promising target for the treatment of RCC.

Structure-Activity Relationship of 5-mer Catalytides, GSGYR and RYGSG

We recently discovered JAL-TA9 (YKGSGFRMI), a short hydrolytic peptide that we termed a Catalytide. The catalytic center of JAL-TA9 was modeled using MM2 and MMFF94 parameters and identified as GSGFR. Additionally, a structure-activity relationship study showed that GSGYR cleaved Aβ11-29. Here, we developed a novel Catalytide in silico. Molecular dynamics simulations of GSGYR and RYGSG using MM2 and MMFF94 parameters suggested that both peptides may form catalytic triads and oxyanion holes. The hydrolytic potency of RYGSG was five times higher than that of GSGYR. Moreover, both peptides showed three common cleavage positions for Aβ11-29; namely, L17-V18, V18-F19, and E22-D23. The aggregation ratio analyzed by the thioflavin-T assay correlated well with proteolytic activity, suggesting that the aggregation of Aβ11-29 was suppressed by the cleavage reaction. Docking simulations with the carbonyl carbon of L17 or the carbonyl carbon of E22 in Aβ11-29 were conducted using the secondary structures of GSGYR and RYGSG. The distance between the hydroxyl group of serine and the carbonyl carbon of the two cleavage sites proved that RYGSG was closer to Aβ11-29 than to GSGYR. This study demonstrated that Catalytides are useful for understanding structure-activity relationships.

Cnot8 eliminates naïve regulation networks and is essential for naïve-to-formative pluripotency transition

Mammalian early epiblasts at different phases are characterized by naïve, formative, and primed pluripotency states, involving extensive transcriptome changes. Here, we report that deadenylase Cnot8 of Ccr4-Not complex plays essential roles during the transition from naïve to formative state. Knock out (KO) Cnot8 resulted in early embryonic lethality in mice, but Cnot8 KO embryonic stem cells (ESCs) could be established. Compared with the cells differentiated from normal ESCs, Cnot8 KO cells highly expressed a great many genes during their differentiation into the formative state, including several hundred naïve-like genes enriched in lipid metabolic process and gene expression regulation that may form the naïve regulation networks. Knockdown expression of the selected genes of naïve regulation networks partially rescued the differentiation defects of Cnot8 KO ESCs. Cnot8 depletion led to the deadenylation defects of its targets, increasing their poly(A) tail lengths and half-life, eventually elevating their expression levels. We further found that Cnot8 was involved in the clearance of targets through its deadenylase activity and the binding of Ccr4-Not complex, as well as the interacting with Tob1 and Pabpc1. Our results suggest that Cnot8 eliminates naïve regulation networks through mRNA clearance, and is essential for naïve-to-formative pluripotency transition.

TOB1 modulates the decidualization of human endometrial stromal cells via the Notch pathway

BACKGROUND

Decidualization is critical for embryo implantation and the success of pregnancy; however, the mechanisms underlying this process remain largely unknown.

MATERIALS AND METHODS

In the present study, RNA sequencing was used to detect the expression levels of transducer of ERBB2/1(TOB1) in endometrial samples derived from proliferative and secretory phases. A decidualization model was induced using the combination of estrogen (E2) and progestin (P4) in human endometrial stromal cells (HESCs). The cell counting kit-8 assay was used to detect the viability of HESCs. Related proteins were detected by qPCR and western blot.

RESULT

The results indicated that TOB1 expression was upregulated in the secretory endometrial samples compared with the corresponding expression observed in the proliferative samples. The expression levels of TOB1 and Notch1 were markedly increased in E2P4-treated HESCs compared with those in the control cells. Treatment with E2P4 strongly suppressed the proliferation of HESCs and induced a G₁-phase cell cycle arrest. These effects were abolished by knockdown of TOB1 or treatment with of the cells with the Notch inhibitor N-[N-(3,5-difluorophenacetyl)-1-alanyl]-S-phenylglycine t-butyl ester.

CONCLUSIONS

Therefore, these findings highlighted an important role for TOB1/Notch signaling in E2P4-induced decidualization in HESCs, which may provide novel targets for improving the endometrial receptivity.

Reactive oxygen species may influence on the crossroads of stemness, senescence, and carcinogenesis in a cell via the roles of APRO family proteins

Excessive reactive oxygen species (ROS) may cause oxidative stress which is involved in aging and in the pathogenesis of various human diseases. Whereas unregulated levels of the ROS may be harmful, regulated basal level of ROS are even necessary to support cellular functions as a second messenger for homeostasis under physiological conditions. Therefore, redox medicine could develop as a new therapeutic concept for human health-benefits. Here, we introduce the involvement of ROS on the crossroads of stemness, senescence, and carcinogenesis in a stem cell and cancer cell biology. Amazingly, the anti-proliferative (APRO) family anti-proliferative proteins characterized by immediate early growth responsive genes may also be involved in the crossroads machinery. The biological functions of APRO proteins (APROs) seem to be quite intricate, however, which might be a key modulator of microRNAs (miRNAs). Given the crucial roles of ROS and APROs for pathophysiological functions, upcoming novel therapeutics should include vigilant modulation of the redox state. Next generation of medicine including regenerative medicine and/or cancer therapy will likely comprise strategies for altering the redox environment with the APROs via the modulation of miRNAs as well as with the regulation of ROS of cells in a sustainable manner.

Expression of B Cell Translocation Gene 1 Protein in Colon Carcinoma and its Clinical Significance

BACKGROUND

Colon cancer is one of the most common malignant tumors, and B cell Translocation Gene (BTG)1 is involved in the occurrence and development of colon cancer, however, the underlying molecular mechanism remains unclear.

OBJECTIVE

In this study, we investigated the expression of BTG1 protein in colon cancer, and its association with clinicopathology and prognosis.

METHODS

The tumor specimens from 59 patients with colon cancer who had undergone radical colectomy were selected as the observation group. Para-carcinoma tissues from the same patients were selected as the control group. The expressions of BTG1 mRNA and protein in the specimen of two groups were analyzed by quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) and Western blot. According to the immunohistochemical results, the patients were divided into BTG1-negative and BTG1-positive groups. The postoperative cumulative survival rate in the two groups was analyzed. The association of the expression of BTG1 protein with the clinicopathological features and postoperative survival was investigated.

RESULTS

Compared with the control group, the expression levels of BTG1 mRNA and BTG1 protein were significantly decreased in the observation group (P < 0.05). Immunohistochemical analysis revealed that there were 12 positive tumor samples and 47 negative samples. The expression of BTG1 was negatively associated with the degree of differentiation and lymphatic metastasis. The cumulative survival rate of BTG1-positive patients was significantly increased compared with that of BTG1- negative patients (P < 0.05). Stepwise Cox regression analysis showed that lymphatic metastasis, tumor size and BTG1 expression level were independent prognostic factors for overall survival in patients with colon cancer.

CONCLUSION

BTG1 protein in colon cancer tissues were expressed at low levels, which was associated with the clinicopathological features, postoperative recurrence and survival of patients.

Tob2 Inhibits TLR-Induced Inflammatory Responses by Association with TRAF6 and MyD88

Optimal activation of TLR pathways is crucial for the initiation of inflammatory responses and eliminating invading micro-organisms. However, excessive of TLR activation may lead to autoimmune and inflammatory diseases. Thus, TLR pathways should be tightly controlled. In this study, we identify Tob2, a Tob/BTG family member, as a suppressor of TLR pathways. Tob2 deficiency enhances TLR-induced NF-κB and MAPK activation and promotes the expression of proinflammatory cytokines in primary peritoneal macrophages of C57BL/6 mice. Furthermore, Tob2-defective C57BL/6 mice may be more susceptible to endotoxemic shock in vivo. Mechanistically, Tob2 interacts with TRAF6 and MyD88 and thus inhibits signaling from the MyD88-TRAF6 complex in primary peritoneal macrophages and HEK293T cells. Therefore, our results uncover a regulatory mechanism of TLR pathways and provide a potential target for the intervention of diseases with excessive TLR activation.

Catalytides derived from the Box A region in the ANA/BTG3 protein cleave amyloid-β fragment peptide

We have recently reported about shorter proteolytic peptides termed Catalytide as general name. JAL-TA9 (YKGSGFRMI), a fragment peptide derived from Box A region of Tob1 protein, is the first Catalytide and cleaves Aβ42 and its fragment peptides. Herein, we demonstrate the enzymatic properties of ANA-TA9 corresponding region to JAL-TA9 in ANA/BTG3 protein. ANA-TA9 showed the auto-proteolytic activity and cleaved 3 kinds of synthetic fragment peptides derived from Aβ42, especially on the central region of Aβ42 with a serine protease like activity. Interestingly, 2 kinds of components, ANA-SA5 (SKGQA) and ANA-YA4 (YRMI), also showed similar proteolytic activity. These results indicate that ANA-TA9 is composed of two different Catalytides.

Glucocorticoids, genes and brain function

The identification of key genes in transcriptomic data constitutes a huge challenge. Our review of microarray reports revealed 88 genes whose transcription is consistently regulated by glucocorticoids (GCs), such as cortisol, corticosterone and dexamethasone, in the brain. Replicable transcriptomic data were combined with biochemical and physiological data to create an integrated view of the effects induced by GCs. The most frequently reported genes were Errfi1 and Ddit4. Their up-regulation was associated with the altered transcription of genes regulating growth factor and mTORC1 signaling (Gab1, Tsc22d3, Dusp1, Ndrg2, Ppp5c and Sesn1) and progression of the cell cycle (Ccnd1, Cdkn1a and Cables1). The GC-induced reprogramming of cell function involves changes in the mRNA level of genes responsible for the regulation of transcription (Klf9, Bcl6, Klf15, Tle3, Cxxc5, Litaf, Tle4, Jun, Sox4, Sox2, Sox9, Irf1, Sall2, Nfkbia and Id1) and the selective degradation of mRNA (Tob2). Other genes are involved in the regulation of metabolism (Gpd1, Aldoc and Pdk4), actin cytoskeleton (Myh2, Nedd9, Mical2, Rhou, Arl4d, Osbpl3, Arhgef3, Sdc4, Rdx, Wipf3, Chst1 and Hepacam), autophagy (Eva1a and Plekhf1), vesicular transport (Rhob, Ehd3, Vps37b and Scamp2), gap junctions (Gjb6), immune response (Tiparp, Mertk, Lyve1 and Il6r), signaling mediated by thyroid hormones (Thra and Sult1a1), calcium (Calm2), adrenaline/noradrenaline (Adcy9 and Adra1d), neuropeptide Y (Npy1r) and histamine (Hdc). GCs also affected genes involved in the synthesis of polyamines (Azin1) and taurine (Cdo1). The actions of GCs are restrained by feedback mechanisms depending on the transcription of Sgk1, Fkbp5 and Nr3c1. A side effect induced by GCs is increased production of reactive oxygen species. Available data show that the brain's response to GCs is part of an emergency mode characterized by inactivation of non-core activities, restrained inflammation, restriction of investments (growth), improved efficiency of energy production and the removal of unnecessary or malfunctioning cellular components to conserve energy and maintain nutrient supply during the stress response.

Metformin improves the angiogenic potential of human CD34⁺ cells co-incident with downregulating CXCL10 and TIMP1 gene expression and increasing VEGFA under hyperglycemia and hypoxia within a therapeutic window for myocardial infarction

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in patients with diabetes mellitus (DM). To identify the most effective treatment for CVD, it is paramount to understand the mechanism behind cardioprotective therapies. Although metformin has been shown to reduce CVD in Type-2 DM clinical trials, the underlying mechanism remains unexplored. CD34(+) cell-based therapies offer a new treatment approach to CVD. The aim of this study was to investigate the effect of metformin on the angiogenic properties of CD34(+) cells under conditions mimicking acute myocardial infarction in diabetes.

METHODS

CD34(+) cells were cultured in 5.5 or 16.5 mmol/L glucose ± 0.01 mmol/L metformin and then additionally ± 4 % hypoxia. The paracrine function of CD34(+) cell-derived conditioned medium was assessed by measuring pro-inflammatory cytokines, vascular endothelial growth factor A (VEGFA), and using an in vitro tube formation assay for angiogenesis. Also, mRNA of CD34(+) cells was assayed by microarray and genes of interest were validated by qRT-PCR.

RESULTS

Metformin increased in vitro angiogenesis under hyperglycemia-hypoxia and augmented the expression of VEGFA. It also reduced the angiogenic-inhibitors, chemokine (C-X-C motif) ligand 10 (CXCL10) and tissue inhibitor of metalloproteinase 1 (TIMP1) mRNAs, which were upregulated under hyperglycemia-hypoxia. In addition metformin, increased expression of STEAP family member 4 (STEAP4) under euglycemia, indicating an anti-inflammatory effect.

CONCLUSIONS

Metformin has a dual effect by simultaneously increasing VEGFA and reducing CXCL10 and TIMP1 in CD34(+) cells in a model of the diabetic state combined with hypoxia. Therefore, these angiogenic inhibitors are promising therapeutic targets for CVD in diabetic patients. Moreover, our data are commensurate with a vascular protective effect of metformin and add to the understanding of underlying mechanisms.