Survival Gene Bcl-2 Research Articles

Effect of Rosolic acid on endothelial dysfunction under ER stress in pancreatic microenvironment

Endothelial cell (EC) dysfunction is the underlying cause for the development of several pathologies, and the interdependency between the pancreatic β-cells and ECs has been established in the pathophysiology of diabetes. ECs release several factors that govern the expression of genes involved in the proliferation, physiology, and survival of the β-cells. Of the known factors that collapse this intricately balanced system, endothelial dysfunction is the crucial condition that manifests as the causative factor for micro and macrovascular diseases. Our earlier studies demonstrated that activation of nuclear factor erythroid-related factor (Nrf2) renders protection to the ECs experiencing ER stress. In this study, using a co-culture system, the crosstalk between pancreatic cells under ER stress and ECs and the effect of a novel Nrf2 activator Rosolic Acid (RA), on the crosstalk was investigated. ECs pre-treated with different concentrations RA and co-cultured with thapsigargin-induced ER stressed pancreatic β-cells showed increased levels of Nrf2 and its downstream targets such as heme oxygenase-1 (HO-1) and NADPH-quinone oxidoreductase-1 (NQO-1), and reduction of ER stress evinced by the decreased levels of glucose-regulated protein (GRP) 78 and C/ERB homologous protein (CHOP). The sensitization of ECs using RA, offered protection to pancreatic cells against ER stress as displayed by increased intracellular insulin and upregulated expression of cell survival and proliferative genes BCl2 and PDX-1. In addition, RA treatment resulted in elevated levels of various angiogenic factors, while inflammatory (TNF-α and IL-1β) and apoptotic markers (CXCL10 and CCL2) decreased. RA treatment normalized the levels of 115 proteins of the 277, which were differentially regulated as revealed by proteomic studies of ER stressed pancreatic β-cells in co-culture conditions. These findings clearly indicate the role of small molecule activators of Nrf2 not only in restoring the functioning of pancreatic cells but also in increasing the cell mass. Further, the study impinges on the strategies that can be developed to balance the pancreatic microenvironment, leading to the restoration of β-cell mass and their normophysiology in diabetic patients.

Molecular events contributing to successful pediatric cardiac transplantation in HLA sensitized recipients

Antibodies to HLA resulting in positive cytotoxicity crossmatch are generally considered a contraindication for cardiac transplantation. However, cardiac transplantations have been performed in children by reducing the Abs and modifying immunosuppression. To identify mechanisms leading to allograft acceptance in the presence of Abs to donor HLA, we analyzed priming events in endothelial cells (EC) by incubating with sera containing low levels of anti-HLA followed by saturating concentration of anti-HLA. Pre-transplant sera were obtained from children with low levels of Abs to HLA who underwent transplantation. EC were selected for donor HLA and exposed to sera for 72 h (priming), followed by saturating concentrations of anti-HLA (challenge). Priming of EC with sera induced the phosphatidylinositol 3-kinase/Akt mediated by the BMP4/WNT pathway and subsequent challenge with panel reactive antibody sera increased survival genes Bcl2 and Heme oxygenase-1, decreased adhesion molecules, induced complement inhibitory proteins and reduced pro-inflammatory cytokines. In contrast, EC which did not express donor HLA showed decreased anti-apoptotic genes. Primed EC, upon challenge with anti-HLA, results in increased survival genes, decreased adhesion molecules, induction of complement inhibitory proteins, and downregulation of pro-inflammatory cytokines which may result in accommodation of pediatric cardiac allografts despite HLA sensitization.

Cladophora glomerata methanolic extract decreases oxidative stress and improves viability and mitochondrial potential in equine adipose derived mesenchymal stem cells (ASCs)

Reactive oxygen species (ROS) are key mediators of several cellular damage and thus associated with equine diseases such as inflammation and metabolic syndrome. This study aimed to evaluate the protective and antioxidant activities of methanolic extract prepared from Cladophora glomerata (C. glomerata) biomass, on equine adipose derived mesenchymal stem cells (EqASCs), under experimental oxidative stress induced by H2O2. Pre-treatment of EqASCs cells with different concentrations of C. glomerata methanolic extract (1% and 5%) provided a clear protection against cellular damage triggered by H2O2. The cell's apoptotic status was significantly regulated, with promotion of cell viability, down-regulation of pro-apoptotic (p21, p53, Bax and Casp-9) genes expression, concomitant to up-regulation of the survival gene Bcl-2, this being supported by a mitigation of the endoplasmic reticulum (ER) stress and significant minimization of mitochondrial dysfunction. The results also showed that C. glomerata extract significantly increased the antioxidant enzymes Superoxide dismutase (SOD) and Catalase (CAT) activities, positively regulated the enzymes genes expression, and markedly reduced the protein carbonyls derivatives production. Finally, RT-qPCR analysis of the inflammatory related genes allowed to highlight a promising anti-inflammatory and immunomodulatory effect of this extract. Due to the valuable antioxidant and anti-inflammatory activities, C. glomerata may have potential benefits for the prevention of equine diseases associated with oxidative stress, including metabolic syndrome.

ANP32A Regulates Histone 3 Acetylation and Promotes Leukemogenesis in AML

Leukemia initiation and progression not only depend on genetic alterations but also on abnormal epigenetic changes that cause disorder of gene expression. Acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) binds directly to histone tails, preferentially to unmodified histone H3 tails (Schneider et al., 2004; Seo et al., 2002). Although ANP32A inhibits histone acetyltransferase activity in vitro (Seo et al., 2002), loss of ANP32A leads to decreased histone 3 acetylation (acetyl-H3) levels on interferon-stimulated genes in human cervical carcinoma HeLa S3 cells (Kadota et al., 2011). Aberrant ANP32A expression has been observed in many solid tumors, which involves in diverse processes depending on the cell context (Brody et al., 2004; Hoffarth et al., 2008), yet mechanisms are still unknown. Furthermore, there has as yet been no specific investigation into the role of ANP32A in acute myeloid leukemia (AML).We found that ANP32A expression was upregulated at both mRNA and protein levels in patients with AML. In AML primary cells from patients, ANP32A KD decreased cell proliferation and colony formation ability. In addition, ANP32A KD induced apoptosis and cell cycle arrest at G1 phase accompanied with the downregulated protein expression of survival or cell cycle progress genes BCL2, CDK4, CCND1 and the upregulated protein expression of pro-apoptosis genes BAK, BAD, cleaved caspase 3. These findings were also verified in various subtypes of AML cell lines and Mll-Af9 pre-leukemic cells. Thus, ANP32A is essential for cell growth via the promotion of cell-cycle progression and inhibition of apoptosis in AML.Given that ANP32A associates with histone acetylation modification, we analyzed the effect of ANP32A depletion on acetyl-H3 and histone 4 acetylation (acetyl-H4). Western blot analysis showed that ANP32A KD caused global decrease of acetyl-H3, but no effect on the global level of acetyl-H4. To investigate the mechanism of ANP32A in AML, ChIP-seq and gene expression microarray experiments were performed to determine acetyl-H3 enrichment and transcriptome profiles, respectively, in ANP32A KD and control K562 cells. We found a positive correlation between changes in gene expression and changes in acetyl-H3 (r=0.16, p<10-4), especially for differential expression genes (DEGs; r=0.40, p<10-4). Moreover, we also found genes with decreased acetyl-H3 enrichment displayed lower expression levels compared with genes with increased acetyl-H3 enrichment (p<10-3). Thus, ANP32A alters acetyl-H3 modification in association with changes in gene expression.Gene set enrichment analysis (GSEA) revealed that ANP32A KD significantly decreased the acetyl-H3 enrichment levels at genes of lipid metabolism signatures (e.g. lipid metabolic process, cholesterol homeostasis). Transcriptome profile analysis using GSEA showed that gene expression levels of lipid metabolic process signature were also reduced after ANP32A KD. We further identified 4 genes (APOC1, CNKSR3, H19, PCSK9) which had significantly lower levels of mRNA expression (p<10-2, FDR<10-2, FC>1.5) and decreased levels of acetyl-H3 enrichment (p<10-2, FDR<10-2, FC>1.5) in ANP32A KD cells. Apolipoprotein CI(APOC1) was the most significantly downregulated gene among these 4 genes, with decreased acetyl-H3 on its promoter. To explore whether lipid metabolism as a downstream effector of ANP32A contributes to ANP32A function in AML, re-introduction of APOC1 was performed in ANP32A KD THP1 or K562 cells. Re-introduction of APOC1 significantly rescued the inhibition of cell growth in ANP32A KD AML cells, also upregulated protein expression of BCL2, CDK4 and CCND1, showing that ANP32A functions in AML partially depending on APOC1. Importantly, APOC1 depletion decreased cell proliferation of AML cells in vitro, consistent with the point of view that complex lipid alterations contribute to endoplasmic reticulum stress-induced apoptosis in cancer cells (Beloribi-Djefaflia et al., 2016; Iurlaro et al., 2016).Overall, our data suggest ANP32A as a novel regulator of leukemogenesis in AML. ANP32A may involve in the regulation of genome-wide histone 3 acetylation that alters the expression of multiple genes, including lipid metabolism related gene APOC1. Thus, ANP32A is a promising drug target for AML therapy. DisclosuresNo relevant conflicts of interest to declare.

Epithelial tumours of the lacrimal gland: a clinical, histopathological, surgical and oncological survey

Editor, Sarah Line′a von Holstein and associates present a review of the primary epithelial tumours of the lacrimal gland describing in the first part the frequency, demographics, clinical presentation and diagnostic features (von Holstein et al. 2013). In the second part, primarily tumour-specific histological characteristics are given. Finally, treatment modalities including surgical procedures and medical oncology as well as prognosis are discussed. Authors are to be commended for their effort to have performed such wide review on epithelial tumours of the lacrimal gland. Those orbital lesions, in fact, still represent a challenge for both clinicians and researchers. However, some relevant information regarding the pathological features and the prognosis was missed. In the section on pathology and molecular characteristics of those tumours, the authors reported that the immunohistological staining of biomarkers, including the androgen receptor, p53 and the HER-2/neu oncoprotein, is strong and diffuses in the malignant area. In this context, it would be important to report even the relation between the expression of apoptosis-related markers and the malignant epithelial tumours of the lachrymal gland (Strianese et al. 2007). Particularly, it was found in a re-examination of the 21 specimens of malignant epithelial tumours of the lacrimal gland that the expression of p53 was directly correlated with the apoptotic index, while expression of Bcl-2 was inversely correlated (Strianese et al. 2007). This expression pattern has been already described in other tumours (Greenblatt et al. 1994). Presumably, the correlation between apoptotic index, p53 and Bcl-2 indicates that tumour cells have lost or down-regulated their survival gene Bcl-2 and up-regulated the expression of p53, to attempt damage repair. Studies on apoptosis and apoptosis-related factors in salivary gland tumours have shown similar correlation as that found in lacrimal gland tumours (Soini et al. 1998). In addition, a statistically significant positive relationship for number of apoptotic cells (TUNEL) and p53, and an inverse correlation for Bcl-2 staining, was demonstrated with overall survival (Strianese et al. 2007). The correlation with survival of apoptotic index, p53 and Bcl-2 expression suggests that the more tumour cells go in apoptosis, up-regulating p53 and down-regulating Bcl-2, the better the survival of patients. As a role of apoptosis regulatory proteins in the pathogenesis of malignant epithelial lacrimal gland tumours was established, the hypothesis that evaluation of the expression of apoptosis-related markers in these tumours may provide a prognostic tool was reported (Strianese et al. 2007). This latter information should be mentioned in a review on epithelial tumours of the lacrimal gland, to provide adequate information for the clinician on prognostic factors of those tumours. As these tumours are rare (Bonavolontà et al. 2013), very little information about the molecular changes leading to their development and progression has so far been reported. Studies on targeting of the apoptosis pathway in epithelial tumours of the lacrimal gland represent an interesting new insight and, indeed, are considered by most researchers the new frontier for the understanding and management of the malignancies (Chaabane et al. 2013). Eventually, this letter may complete the wide review of van Holstein and associates.

Calcium and osteoprotegerin regulate IGF1R expression to inhibit vascular calcification

Osteoprotegerin (OPG) inhibits vascular calcification in vitro, and OPG(-/-) mice develop vascular calcification. Insulin-like growth factor-1 (IGF1) signalling has been implicated in vascular smooth muscle cell (VSMC) survival; however, the role of IGF1-receptor (IGF1R) expression in calcification is unclear. We sought to determine whether the protective effects of OPG in vascular calcification were mediated by IGF1R. Calcium-induced mineralization of VSMCs was blocked in cells expressing the IGF1R and by treatment with OPG. OPG induced IGF1R mRNA, protein, and transcription optimally at 1 ng/mL. Calcium also positively regulated both OPG and IGF1R, and siRNA targeting of OPG inhibited calcium-inducible IGF1R mRNA. Addition of calcium to VSMCs reduced camptothecin-stimulated apoptosis and increased expression of survival genes Bcl2 and nuclear factor-kappa B without altering levels of proliferation. Calcium's induction of IGF1R and OPG was dose and time dependent but was blunted at higher calcium doses. Calcium- and OPG-inducible IGF1R transcription occurred between -446 and -188 bp of the IGF1R promoter, and inducible-IGF1R expression was blocked by specificity protein-1 (Sp1) silencing studies. Furthermore, elevated IGF1R and OPG protein levels were present in calcified atherosclerotic tissue. We have shown for the first time that IGF1R expression and activity via OPG can modulate VSMC calcification in vitro. We suggest a feedback mechanism: moderate calcium levels increase OPG, which then increases IGF1R to enhance VSMC survival and block calcification induced by calcium. In contrast, high calcium leads to inhibition of IGF1R expression and activity to stimulate VSMC calcification further.

Liver X receptors interfere with cytokine-induced proliferation and cell survival in normal and leukemic lymphocytes

Liver X receptors (LXRs) are nuclear receptors regulating lipid and cholesterol metabolism. Recent data indicate an additional role of LXR in immunity by controlling dendritic cell and T-cell function and in breast and prostate cancer cells. Here, we show that LXR activation interferes with IL-2 and IL-7-induced proliferation and cell cycle progression of human T-cell blasts mainly through inhibited phosphorylation of the retinoblastoma protein and decreased expression of the cell cycle protein cyclin B. Comparable results were obtained with IL-2-dependent chronic lymphoblastic leukemia (CLL) T cells. Furthermore, we show for B-CLL cells that LXR are functionally active and inhibit expression of survival genes bcl-2 and MMP-9, and significantly reduce cell viability, suggesting an interference of LXR with cytokine-dependent CLL cell survival. In conclusion, our data reveal LXR as a potent modulator of cytokine-dependent proliferation and survival of normal and malignant T and B lymphocytes. This novel LXR action could find clinical application in immunosuppressive and antileukemic therapies.

δ-Catenin promotes prostate cancer cell growth and progression by altering cell cycle and survival gene profiles

Backgroundδ-Catenin is a unique member of β-catenin/armadillo domain superfamily proteins and its primary expression is restricted to the brain. However, δ-catenin is upregulated in human prostatic adenocarcinomas, although the effects of δ-catenin overexpression in prostate cancer are unclear. We hypothesized that δ-catenin plays a direct role in prostate cancer progression by altering gene profiles of cell cycle regulation and cell survival.ResultsWe employed gene transfection and small interfering RNA to demonstrate that increased δ-catenin expression promoted, whereas its knockdown suppressed prostate cancer cell viability. δ-Catenin promoted prostate cancer cell colony formation in soft agar as well as tumor xenograft growth in nude mice. Deletion of either the amino-terminal or carboxyl-terminal sequences outside the armadillo domains abolished the tumor promoting effects of δ-catenin. Quantitative RT2 Profiler™ PCR Arrays demonstrated gene alterations involved in cell cycle and survival regulation. δ-Catenin overexpression upregulated cyclin D1 and cdc34, increased phosphorylated histone-H3, and promoted the entry of mitosis. In addition, δ-catenin overexpression resulted in increased expression of cell survival genes Bcl-2 and survivin while reducing the cell cycle inhibitor p21Cip1.ConclusionTaken together, our studies suggest that at least one consequence of an increased expression of δ-catenin in human prostate cancer is the alteration of cell cycle and survival gene profiles, thereby promoting tumor progression.

CCL3L1 prevents gp120-induced neuron death via the CREB cell signaling pathway

Neurodegeneration is a characteristic feature of AIDS dementia complex and is commonly associated with neuronal death in the brains of both pediatric and adult patients. Neuronal death associated with AIDS dementia complex can be induced by the HIV-1 protein gp120, but the underlying signal transduction mechanism remains unclear, especially for HIV-1 subtypes commonly seen in China. We have now demonstrated that the human CC ligand 3-like protein 1 (CCL3L1), a member of the CC chemokine family, appears to protect neuronal cultures through its ability to attenuate gp120-induced neuronal death. We found that (i) both pCREB levels and Bcl-2 expression are up-regulated in neuronal culture following treatment with CCL3L1 plus gp120; (ii) CCL3L1 induces cell survival via phosphorylation of CREB by way of the PKA and CaMKI/CaMKIV cell signaling pathways; (iii) transcription of the cell survival gene bcl-2 is induced by pCREB; and (iv) CCL3L1 protects cultured neurons against CCR5-mediated excitotoxicity induced by gp120. Thus, the CCL3L1/bcl-2-regulated anti-apoptotic pathway significantly contributes to reduction of HIV-1/gp120-induced neuronal apoptosis, and therefore, CCL3L1 should be further investigated as a potential chemokine to protect against neuronal injury in gp120-related neuronal toxicity.

Cell protective mechanism of valproic acid in lethal hemorrhagic shock

We have demonstrated that valproic acid (VPA), a histone deacetylase inhibitor, can improve animal survival after hemorrhagic shock and protect neurons from hypoxia-induced apoptosis. This study investigated whether VPA treatment works through the beta-catenin survival pathways. Wistar-Kyoto rats underwent hemorrhagic shock (60% blood loss) followed by treatment with or without VPA (300 mg/kg). Brains were harvested after 1, 6, and 24 hours and analyzed for acetylated histone-H3 at lysine-9 (Ac-H3K9), acetylated and total beta-catenin, and Bcl-2 by Western blot. In addition, primary neurons dissociated from E18 rat embryos were exposed to hypoxia (0.5% O(2)) for 16 hours with or without VPA (1 mmol/L) and analyzed using confocal microscopy. After treatment of hemorrhaged animals with VPA, acetylated beta-catenin was found in both the cytosol and nucleus, along with Ac-H3K9. Bcl-2 transcript increased after 1 hour followed by an increase in Bcl-2 protein at 6 hours. Confocal imaging demonstrated that after VPA treatment, beta-catenin translocated into the nucleus and colocalized with Ac-H3K9. VPA treatment acetylates H3K9 and beta-catenin and enhances translocation of beta-catenin into the nucleus, where it colocalizes with Ac-H3K9 and stimulates the transcription of survival gene bcl-2. This finding suggests that VPA protects cells after severe insult through the beta-catenin survival pathway.

61: Recombinant adenoviral gene transfer by ex vivo perfusion does not affect cardiac allograft vasculopathy

occurring during accelerated rejection of cardiac allografts in presensitized recipients. Methods and Materials: LEW rats (n 12) were sensitized with WF skin grafts, followed 7 days later by transplantation of WF hearts. Results: These grafts were rejected within 24 hours post transplantation. Lymphocytes from presensitized recipients showed significant host cell proliferation in MLR cytotoxicyty in LMC accompanied by the occurrence of anti-donor allo-antibodies in the recipients’ sera at the time of graft loss ( FACS analysis). Immunohistochemical studies of accelerately rejecting cardiac allografts revealed a dense infiltration with MHC class II bearing cells, monocytes and macrophages (ED1) as well as T-cells (R73). In addition, apoptosis was observed during accelerated rejection of cardiac allografts (but not in the recipients naive hearts) as demonstrated by DNA laddering and TUNEL assay. Western blot analysis revealed a marked down regulation of the survival gene Bcl-2 in accelerated rejecting allografts, in comparison to naive and isograft control hearts. Reduction of Bcl-2 protein levels seems to be mediated by a proteolytical degradation, since quantitative RT-PCR analysis disclosed no alteration of Bcl-2 mRNA levels. Conclusions: Apoptosis was discovered as a so far unknown effector mechanism in accelerated cardiac transplant rejection which accompanies combined cellular and humoral immune alloreactivity. Apoptotic cell death in accelerateled rejection as well as the cascade of upand downstream events leading to apoptosis should be considered as critical steps and potential therapeutical targets in the pathogenesis of accelerated rejection.

Effect of bcl-2 overexpression in mice on ovotoxicity caused by 4-vinylcyclohexene

The occupational chemical 4-vinylcyclohexene (VCH) destroys small preantral ovarian follicles in mice following repeated daily dosing. The cell survival gene bcl-2 is thought to protect against follicular death during embryogenesis because primordial follicle numbers in newborn bcl-2 overexpressing (OE) mice are greater than in wild-type (WT) controls. Thus, this study was designed to determine if overexpression of bcl-2 protects against VCH-induced follicle loss during embryonic development. Pregnant bcl-2 OE or WT mice were dosed (p.o.) daily with VCH (500 mg/kg) or sesame oil (vehicle control) on days 8-18 of pregnancy. Ovaries were collected from moms and female pups on pup postnatal day (PND) 8. Nonpregnant OE and WT females were also treated with VCH (500 mg/kg p.o.) or vehicle and evaluated in the same manner. As previously reported, ovaries from PND8 OE female pups contained 50% more primordial follicles than WT pups (P < 0.05). Unlike WT pups, relative to vehicle controls, in utero exposure to VCH resulted in a reduction in primordial (25% of control), primary (38% of control), and secondary (33% of control) follicles in ovaries of OE pups (P < 0.05). VCH had no significant effect on follicle numbers in OE or WT moms. Conversely, in nonpregnant adults, VCH did not affect WT mice but caused loss of primordial (55% of control), primary (51% of control), and secondary (69% of control) follicles in OE mice (P < 0.05). These results demonstrate that bcl-2 overexpression does not protect against, but instead increases susceptibility to VCH-induced follicle loss in transplacentally exposed or in nonpregnant mice.

Valproic acid inhibits growth, induces apoptosis, and modulates apoptosis-regulatory and differentiation gene expression in human thyroid cancer cells

Among the most promising new therapies for thyroid cancer are the histone deacetylase inhibitors. Valproic acid (VA) is an anticonvulsant that inhibits histone deacetylase activity at nontoxic concentrations. We hypothesized that VA would have antineoplastic effects on human thyroid cancer cells. We treated 1 papillary and 3 follicular thyroid cancer cell lines with VA (0.5-2 mmol/L) for 24 to 72 hours. Cell proliferation was measured with a cell proliferation assay kit. Annexin V-fluorescein isothiocyanate was used to quantitate cells that were undergoing apoptosis. Quantitative polymerase chain reaction was used to measure expression of apoptosis-regulatory and differentiation genes. VA inhibited growth in all cell lines by 26% to 59% at 48 hours and up to 77% at 72 hours. Nineteen percent to 30% of VA-treated cells underwent apoptosis, compared with 4% to 8% of the control cells. Expression of pro survival genes bcl-2 and bcl-xl was down-regulated by 10% to 60%; expression of the proapoptosis gene bax was up-regulated by 23% to 85%. Sodium-iodide symporter and thyroglobulin messenger RNA expression were up-regulated by 93% to 370% in follicular cell lines but remained unchanged in the papillary cell line. VA inhibits growth, induces apoptosis, and modulates apoptosis-regulatory and differentiation gene expression in thyroid cancer cells. These findings suggest that VA may be useful clinically for patients with thyroid cancers of follicular cell origin.

Mouse cDNA microarray analysis uncovers Slug targets in mouse embryonic fibroblasts

There is a need to reveal mechanisms that account for maintenance of the mesenchymal phenotype in normal development and cancer. Slug (approved gene symbol Snai2), a member of the Snail gene family of zinc-finger transcription factors, is believed to function in the maintenance of the nonepithelial phenotype. This study identified candidate Slug target genes linked to Slug gene suppression in primary mouse embryonic fibroblasts. Expression analyses were performed with a mouse cDNA microarray (Mousechip-CNIO) containing 15,000 clones. A total of 15 novel Slug target species were validated by real-time PCR or Western analyses. These included self-renewal genes ( Bmi1, Nanog, Gfi1), epithelial–mesenchymal genes ( Tcfe2a, Ctnb1, Sin3a, Hdac1, Hdac2, Muc1, Cldn11), survival genes ( Bcl2, Bbc3), and cell cycle/damage genes ( Cdkn1a, Rbl1, Mdm2). Expression patterns were studied in wild-type MEFs and Slug-deficient MEFs. Slug-complementation studies recovered aberrant gene expression in cells lacking Slug, indicating that these genes were regulated directly by Slug. These results highlight their potential roles in mediating Slug function in mesenchymal cells and may help to identify novel therapeutic biomarkers in cancers linked to Slug.

Neuronal protection from glucose deprivation via modulation of glucose transport and inhibition of apoptosis: a role for the insulin-like growth factor system

Glucose is the brain's major energy source; therefore, loss of neuronal cells is a potential consequence of hypoglycaemia. Since apoptosis is a major mechanism of neuronal loss following a range of insults, we explored potent anti-apoptotic systems (IGF-I and bcl-2) as means of enhancing neuronal survival in the face of glucose deprivation. Human neuroblastoma cells (SH-SY5Y, SHEP and SHEP-bcl-2) were exposed to low glucose as a model of glucopenia-induced neuronal damage. Administration of IGF-I and/or over-expression of the survival gene bcl-2 were exploited to attempt to limit neuronal loss. Neuronal survival mechanisms and interactions between these systems were investigated. Low glucose (0.25–2.5 mM) adversely affected cell growth and survival; however, IGF-I ameliorated these outcomes. Over-expression of bcl-2 blunted low glucose-induced apoptosis and up-regulated IGF-I receptor, with the effect of IGF-I addition being negligible on apoptosis, while significantly enhancing mitochondrial activity. In SH-SY5Y cells, IGF-I significantly changed >two-fold mRNA levels of the apoptosis-related genes gadd45, fas, iNOS, NFkB, TRAIL, without further affecting bcl-2 expression. In low glucose, IGF-I acutely enhanced glucose transport and translocation of GLUT1 protein to the cell membrane. GLUT1 mRNA expression was up-regulated by both IGF-I and bcl-2. The potent anti-apoptotic systems IGF-I and bcl-2 are both thus able to enhance cell survival in a glucose-deprived human neuronal model. Although we clearly show evidence of positive cross-talk via bcl-2 modulation of IGF-I receptor, IGF-I also has enhancing effects on mitochondrial function outside the bcl-2 pathway. The common effect of both systems on enhancement of GLUT-1 expression suggests that this is a key mechanism for enhanced survival. These studies also point to the potential use of IGF-I therapy in prevention or amelioration of hypoglycaemic brain injury.

Engraftment of a vascularized human skin equivalent.

Clinical performance of currently available human skin equivalents is limited by failure to develop perfusion. To address this problem we have developed a method of endothelial cell transplantation that promotes vascularization of human skin equivalents in vivo. Enhancement of vascularization by Bcl-2 overexpression was demonstrated by seeding human acellular dermis grafts with human umbilical vein endothelial cells (HUVEC) transduced with the survival gene Bcl-2 or an EGFP control transgene, and subcutaneous implantation in immunodeficient mice (n=18). After 1 month the grafts with Bcl-2-transduced cells contained a significantly greater density of perfused HUVEC-lined microvessels (55.0/mm3) than controls (25.4/mm3,P=0.026). Vascularized skin equivalents were then constructed by sequentially seeding the apical and basal surfaces of acellular dermis with cultured human keratinocytes and Bcl-2-transduced HUVEC, respectively. Two weeks after orthotopic implantation onto mice, 75% of grafts (n=16) displayed both a differentiated human epidermis and perfusion through HUVEC-lined microvessels. These vessels, which showed evidence of progressive maturation, accelerated the rate of graft vascularization. Successful transplantation of such vascularized human skin equivalents should enhance clinical utility, especially in recipients with impaired angiogenesis.

Insights into the molecular mechanism of apoptosis induced by TNF-α in mouse epidermal JB6-derived RT-101 cells

The mammalian response to stress is complex, often involving multiple signaling pathways that act in concert to influence cell fate. To examine potential interaction between the signaling cascade, we have focused on the effects of a model apoptotic system in a single cell type sensitive to TNF-α induced apoptosis through an examination of the relative influences of MAPKs as well as transcription factors AP-1, NF-κB, and various survival genes in determining apoptosis. Our results show that ERKs decreased transiently or remain unchanged, JNK decreased robustly, whereas c-Jun increased transiently, thereby indicating that members of MAPK family are differentially regulated in response to TNF-α induced apoptosis, whereas NF-κB protein expression decreased transiently and activity decreased at 24 h post-treatment. The survival genes Bcl-2, Bcl-XL, and survivin act independently and downstream of ERK and JNK to decrease the survival of TNF-α treated RT-101 cells. The results also suggest the involvement of the mitochondria and cytochrome c. Caspase-3 appears to be a part of a downstream event.

Leptin attenuates follicular apoptosis and accelerates the onset of puberty in immature rats

Human and rat granulosa cells express receptors to leptin which synergies with glucocorticoid hormones in stimulation of ovarian steroidogenesis. To examine whether leptin affects follicular development and maturation, we injected recombinant ovine leptin (300 ng-10 μg/animal) daily to immature 21 day-old female rats. Non-treated rats reached puberty at 44.5±1.6 ( n=9) days. In contrast, in leptin treated animals, puberty was reached at 34.5±1.6 ( n=9) days. Ovarian sections revealed hypertrophy of granulosa cells in leptin treated animals. Moreover, the number of ovulations was 2-fold higher in the treated animals compared to controls (3–4 ovulations versus 7–8 on the first three estrous cycles, P<0.001). Leptin dramatically reduced incidence of follicular apoptosis measured by TUNEL, and was already evident after 7 days of leptin injection (12% of apoptosis in leptin treated group compared to 52% in controls, P<0.001). Maximal protection against apoptosis was achieved at 1–3 μg leptin/animal. The levels of FSH, LH, progesterone and the steroidogenic factors ADX and STAR were elevated earlier in development in the leptin treated animals compared to control animals which is in line with the achievement of early puberty in the leptin treated animals compared to non treated ones. To reveal whether modulation of death and survival genes is involved in leptin attenuation of follicular apoptosis, we examined the expression of the survival gene Bcl-2 and the death gene Bax in Western blots of ovarian homogenates. There was a pronounced elevation in Bcl-2 expression during 7–14 days of leptin injections up to 16.3-fold ( P<0.001) compared to Bcl-2 expression in controls. Bax expression was elevated only 3.4 fold ( P<0.001), leading to an increase in the Bcl-2/Bax ratio of 4.7 fold ( P<0.001). Expression of the tumor suppressor gene p 53 and the oncogene Mdm2 did not change significantly. Our data suggests that leptin may be involved in accelerating follicular maturation by attenuating follicular atresia and increasing the ratio of Bcl-2/Bax.

Expression of apoptosis regulatory genes in chronic cyclosporine nephrotoxicity favors apoptosis

Expression of apoptosis regulatory genes in chronic cyclosporine nephrotoxicity favors apoptosis. Chronic cyclosporine (CsA) nephrotoxicity is characterized by interstitial fibrosis, tubular dropout, and loss of cellularity in areas of fibrosis. Apoptosis was found to play a role in CsA-induced fibrosis. We evaluated the role of the death genes p53, Bax, and Fas-L (ligand), survival gene Bcl-2, interleukin-converting enzyme (ICE), and caspase-3. Salt-depleted rats were administered CsA 15 mg/kg/day or vehicle (VH) and were sacrificed at 7 or 28 days. Apoptosis was detected by TdT-mediated dUTP-biotin nick end labeling assay. p53 and Bax expressions were evaluated by Northern and Western blot analysis. Fas-L and Bcl-2 expressions were evaluated by immunofluorescence. In addition to ICE mRNA, caspase-3 enzymatic activity was assayed. Although no differences were seen at one week, apoptosis-positive cells increased with CsA at four weeks (P < 0.05) and correlated with tubular atrophy and interstitial fibrosis (r = 0.8, P < 0.05). CsA induced the expression of p53 (P < 0.05) and Bax (P < 0.01) and decreased that of Bcl-2 (P < 0.05). CsA up-regulated Fas-L expression (P < 0.001). ICE mRNA and caspase-3 activity were also increased (P < 0.01). The changes occurred as early as one week and remained statistically significant at four weeks. Specific apoptotic genes are increased in chronic CsA nephrotoxicity. The balance favors the induction of apoptosis. Increased apoptosis could explain the tubular dropout and loss of cellularity with fibrosis. This then may impair the ability of the tubulointerstitium to remodel. Apoptosis could also contribute to some of CsA immunosuppressive effects on activated lymphocytes.

A link between cell cycle and cell death: Bax and Bcl-2 modulate Cdk2 activation during thymocyte apoptosis.

Resting thymocytes undergoing apoptosis in response to specific stimuli degrade the cdk inhibitor p27(Kip1) and upregulate Cdk2 kinase activity. Inhibition of Cdk2 kinase activity efficiently blocks cell death via certain apoptosis pathways whereas overexpression of Cdk2 accelerates such cell death, suggesting its involvement in the signal transduction pathways activated by certain apoptotic stimuli. We found that Cdk2 activation during thymocyte apoptosis can be regulated by p53, Bax and Bcl-2. The highly elevated Cdk2 kinase activity in the apoptosing thymocytes is not associated with its canonical cyclins, cyclin E and cyclin A, and requires de novo synthesis of proteins for activation to take place. We therefore propose Cdk2 activation to be a crucial event in distinct pathways of apoptosis and the point at which the cell cycle and cell death pathways interact.