Positive Regulator Of Proliferation Research Articles

Double Plasma Molecular Adsorption System with Sequential Low-dose Plasma Exchange in Patients with Hepatitis B Virus-related Acute-on-chronic Liver Failure: A Prospective Study.

To investigate the safety and efficacy of double plasma molecular adsorption system (DPMAS) with sequential low-dose plasma exchange (LPE) in treating early hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF). Clinical data of patients with HBV-ACLF were prospectively collected, including patients in a DPMAS with sequential LPE (DPMAS+LPE) group and those in a standard medical treatment (SMT) group. The primary endpoint was death or liver transplantation (LT) at 12 weeks of follow-up. Propensity-score matching was performed to control the effects of confounding factors on prognosis between the two groups. After 2 weeks, total bilirubin, alanine aminotransferase, blood urea nitrogen levels, and Chinese Group on the Study of Severe Hepatitis B score, were significantly lower in the DPMAS+LPE group than those in the SMT group (p<0.05). After 4 weeks, laboratory parameters of the two groups were similar. The cumulative survival rate of the DPMAS+LPE group was significantly higher than that of the SMT group at 4 weeks (97.9% vs. 85.4%, p=0.027), but not at 12 weeks (85.4% vs. 83.3%, p=0.687). Cytokine levels were significantly lower in 12-week survival group than in the death-or-LT group (p<0.05). Functional enrichment analysis showed that downregulated cytokines were mainly involved in positive regulation of proliferation and activation of lymphocytes and monocytes, regulation of immune effect response, regulation of endotoxin response, and glial cell proliferation. DPMAS+LPE significantly improved the 4-week cumulative survival rate, and ameliorated the inflammatory response in patients. DPMAS+LPE may be a promising modality for patients with early HBV-ACLF.

SETD1A promotes the proliferation and glycolysis of nasopharyngeal carcinoma cells by activating the PI3K/Akt pathway.

Nasopharyngeal carcinoma is one of the common malignant tumors that the pathogenesis has not yet been completely defined. SETD1A (histone lysine methyltransferase SET domain-containing 1A) is related to the occurrence of various cancers. However, the role of SETD1A in nasopharyngeal carcinoma remains unclear. The SETD1A overexpression vector, si-NC, si-SETD1A#1, and si-SETD1A#2 were transfected into nasopharyngeal carcinoma cells to overexpress or knockdown SETD1A expression. The assay of biofunction was used to explore the role of SETD1A in nasopharyngeal carcinoma cells. The assay of glucose uptake, lactate release, ATP level, western blot, cell proliferation, and cellular apoptosis analysis were performed to investigate the potential mechanism of SETD1A regulation in nasopharyngeal carcinoma. This study was the first to show that SETD1A was upregulated in nasopharyngeal carcinoma cells and the overexpression of SETD1A significantly promoted the cell proliferation and glycolysis and suppressed the cellular apoptosis. Moreover, SETD1A enhances aerobic glycolysis and cell biological function of nasopharyngeal carcinoma cells via PI3K/AKT signaling pathway. SETD1A induced PI3K/AKT activation and subsequently prevented cellular apoptosis. In conclusion, this study identified overexpressed SETD1A as a positive regulator of proliferation that induced nasopharyngeal carcinoma cells' aerobic glycolysis via PI3K/AKT signaling activation in vitro. This study laid a strong foundation for unveiling the precise anticancer mechanism of SETD1A. The SETD1A may become a novel biomarker for further inhibitor design to obstruct the PI3K/AKT-dependent nasopharyngeal carcinoma progression.

THE TRANSLATIONAL POSSIBILITY OF TARGETING LncRNAs AS A THERAPEUTIC STRATEGY FOR IDIOPATHIC PULMONARY FIBROSIS

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease (ILD). IPF causes stiffness in the lungs which makes it difficult to breathe and get oxygen to the bloodstream. IPF is a particularly severe form of lung fibrosis with no completely known etiology and a median survival of 2.5−3.5 years after diagnosis. The phenotypic changes in the lung fibroblasts are believed to contribute to the development of idiopathic pulmonary fibrosis. Long intergenic non-coding RNAs (LncRNAs) have been identified as novel regulators of gene expression and protein activity. In non-stimulated cells, it showed reduced proliferation and inflammation but no difference in the fibrotic response of IPF fibroblasts. These functional changes in non-stimulated cells were associated with changes in the expression of the histone marks, H3K4me1, H3K4me3, and H3K27ac indicating a possible involvement of epigenetics. Following activation with TGF-β1 and IL-1β, it demonstrated an increased fibrotic but reduced inflammatory response in IPF fibroblasts. No significant difference in proliferation following PDGF exposure was observed. The LncRNAs, LINC00960, and LINC01140 were upregulated in IPF fibroblasts. Knockdown studies showed that LINC00960 and LINC01140 were positive regulators of proliferation in both control and IPF fibroblasts but had no effect on the fibrotic response. Knockdown of LINC01140 but not LINC00960 increased the inflammatory response, which was greater in IPF compared to control fibroblasts. Overall, this review study tries to emphasize the role of LncRNAs as regulators of proliferation and inflammation in human lung fibroblast, a biomarker in IPF, and a novel treatment approach.

Abstract PS18-31: Identification of cell surface proteins in triple negative breast cancer for the development of novel targeted therapies

Abstract Triple negative breast cancer (TNBC) stands out due to its aggressive course and high metastatic rates. No consistent protein biomarker has been described for TNBC, resulting in a scarcity of adjuvant therapies for the afflicted patients. Hence, there is an urgent need to determine novel TNBC-associated proteins for the development of new therapeutics and the identification of novel molecular mechanisms driving this malignancy. Cell surface proteins represent attractive targets for novel therapies, due to their easily accessible localization and their involvement in essential signaling pathways. Objectives: We aimed to uncover novel TNBC-associated cell surface proteins involved in carcinogenesis and metastasis for the development of novel targeted therapeutics. Rationale: Taking advantage of the fact that cell surface proteins are often N-glycosylated, we employed hydrazide chemistry to isolate N-glycopeptides. The glycoproteome of six immortalized TNBC cell lines and five ‘healthy’ controls (HC) (the immortalized cell line MCF10A and four patient-derived human mammary epithelial cell lines) was analyzed using LC-MS/MS and label-free quantification. A data mining strategy was employed to select candidates of interest. We knocked-down (k.d.) the top five candidates of interest (using siRNA technology) and evaluated cell growth using growth-curve analysis. Plexin B3 (PLXNB3) was selected for subsequent functional validations. The effects of PLXNB3 k.d. (using siRNA and CRISPR technology) on cancer cell growth, apoptosis and adhesion were interrogated using western blotting and standard cell biology protocols.Results: The N-glycoproteomics approach led to the identification of 1044 glycoproteins, with over 70% described as plasma membrane/secreted proteins. Gene Ontology analysis revealed that the TNBC-associated glycoproteome was enriched in biological processes such as: mesenchyme development, MAPK signaling, positive regulation of proliferation and regulation of neuron projection development. Candidates of interest were selected from our list by focusing on those plasma membrane proteins that were enriched in TNBC cells compared to HC according to our label-free quantified proteomics data, and that showed limited expression in healthy tissues according to the Human Protein Atlas. We further restricted the list of candidates to those proteins whose k.d. impaired cancer cell growth, with little effect on the HC. PLXNB3, an understudied protein typically expressed in healthy neuronal tissues, was selected for in depth functional analysis. Elevated mRNA PLXNB3 levels in breast cancer patients is associated with poorer overall survival compared to low mRNA expression (Integrated TCGA Pan-Cancer Clinical Data Resource, 2018). PLXNB3 k.d. (using siRNA and CRISPR technologies) impaired TNBC cell growth (in both adherent and spheroid cultures) and was associated with elevated levels of cleaved-caspase 3 and cleaved-caspase 7 compared to scrambled controls. Furthermore, PLXNB3 k.d. negatively impacted TNBC cell adhesion to extracellular matrixes compared to scrambled controls. Subsequent tests will evaluate PLXNB3’s role in tumor growth and metastasis in vivo, using orthotopic tumor models in immunocompromised mice. Citation Format: Laura Kuhlmann, Ankit Sinha, Vladimir Ignatchenko, Andrew Macklin, Lydia Liu, Meinusha Govindarajan, Amanda Khoo, Salvador Mejia-Guerrero, Jennifer Cruickshank, Hal Berman, Thomas Kislinger. Identification of cell surface proteins in triple negative breast cancer for the development of novel targeted therapies [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS18-31.

Long intergenic non-coding RNAs regulate human lung fibroblast function: Implications for idiopathic pulmonary fibrosis

Phenotypic changes in lung fibroblasts are believed to contribute to the development of Idiopathic Pulmonary Fibrosis (IPF), a progressive and fatal lung disease. Long intergenic non-coding RNAs (lincRNAs) have been identified as novel regulators of gene expression and protein activity. In non-stimulated cells, we observed reduced proliferation and inflammation but no difference in the fibrotic response of IPF fibroblasts. These functional changes in non-stimulated cells were associated with changes in the expression of the histone marks, H3K4me1, H3K4me3 and H3K27ac indicating a possible involvement of epigenetics. Following activation with TGF-β1 and IL-1β, we demonstrated an increased fibrotic but reduced inflammatory response in IPF fibroblasts. There was no significant difference in proliferation following PDGF exposure. The lincRNAs, LINC00960 and LINC01140 were upregulated in IPF fibroblasts. Knockdown studies showed that LINC00960 and LINC01140 were positive regulators of proliferation in both control and IPF fibroblasts but had no effect upon the fibrotic response. Knockdown of LINC01140 but not LINC00960 increased the inflammatory response, which was greater in IPF compared to control fibroblasts. Overall, these studies demonstrate for the first time that lincRNAs are important regulators of proliferation and inflammation in human lung fibroblasts and that these might mediate the reduced inflammatory response observed in IPF-derived fibroblasts.

Long Noncoding RNA DANCR Is a Positive Regulator of Proliferation and Chondrogenic Differentiation in Human Synovium-Derived Stem Cells.

Cartilage tissues have limited capacity for repair after damage and then cause osteoarthritis, so finding alternative treatment is ongoing. Mesenchymal stem cells (MSCs) have become a promising therapy for cartilage damage and diseases due to the advantages of easy separation, high proliferative potentiality, and genetic stability. Synovium-derived MSCs (SMSCs) have been recognized as an ideal source for cartilage repair. In our previous study, we found that Sox4 promoted proliferation and chondrogenesis of SMSCs through upregulation of long noncoding RNA (lncRNA) DANCR. However, the exact molecular mechanism by which DANCR promotes proliferation and chondrogenesis of SMSCs remains unknown. In the present study, we investigated the effect of lncRNA DANCR on the proliferation and chondrogenesis of SMSCs. We found that overexpression of DANCR could promote proliferation and chondrogenesis of SMSCs, while knockdown of DANCR had the opposite effect. Moreover, our data demonstrated that DANCR directly interacted with myc, Smad3, and STAT3 mRNA to regulate their stability. Finally, we found that the promotion of SMSC proliferation induced by DANCR depended on myc. Also, DANCR activated chondrogenesis of SMSCs via upregulation of Smad3 and STAT3 expression. Our growing knowledge of the role of DANCR is pointing toward its potential use as a novel therapeutic approach for cartilage damage and diseases.

An inhaled dose of budesonide induces genes involved in transcription and signaling in the human airways: enhancement of anti- and proinflammatory effector genes.

Although inhaled glucocorticoids, or corticosteroids (ICS), are generally effective in asthma, understanding their anti‐inflammatory actions in vivo remains incomplete. To characterize glucocorticoid‐induced modulation of gene expression in the human airways, we performed a randomized placebo‐controlled crossover study in healthy male volunteers. Six hours after placebo or budesonide inhalation, whole blood, bronchial brushings, and endobronchial biopsies were collected. Microarray analysis of biopsy RNA, using stringent (≥2‐fold, 5% false discovery rate) or less stringent (≥1.25‐fold, P ≤ 0.05) criteria, identified 46 and 588 budesonide‐induced genes, respectively. Approximately two third of these genes are transcriptional regulators (KLF9, PER1, TSC22D3, ZBTB16), receptors (CD163, CNR1, CXCR4, LIFR, TLR2), or signaling genes (DUSP1, NFKBIA, RGS1, RGS2, ZFP36). Listed genes were qPCR verified. Expression of anti‐inflammatory and other potentially beneficial genes is therefore confirmed and consistent with gene ontology (GO) terms for negative regulation of transcription and gene expression. However, GO terms for transcription, signaling, metabolism, proliferation, inflammatory responses, and cell movement were also associated with the budesonide‐induced genes. The most enriched functional cluster indicates positive regulation of proliferation, locomotion, movement, and migration. Moreover, comparison with the budesonide‐induced expression profile in primary human airway epithelial cells shows considerable cell type specificity. In conclusion, increased expression of multiple genes, including the transcriptional repressor, ZBTB16, that reduce inflammatory signaling and gene expression, occurs in the airways and blood and may contribute to the therapeutic efficacy of ICS. This provides a previously lacking insight into the in vivo effects of ICS and should promote strategies to improve glucocorticoid efficacy in inflammatory diseases.

Functional and therapeutic significance of protein kinase D enzymes in invasive breast cancer.

The protein kinase D (PKD) family members, PKD1, PKD2 and PKD3 constitute a family of serine/threonine kinases that are essential regulators of cell migration, proliferation and protein transport. Multiple types of cancers are characterized by aberrant expression of PKD isoforms. In breast cancer PKD isoforms exhibit distinct expression patterns and regulate various oncogenic processes. In highly invasive breast cancer, the leading cause of cancer-associated deaths in females, the loss of PKD1 is thought to promote invasion and metastasis, while PKD2 and upregulated PKD3 have been shown to be positive regulators of proliferation, chemoresistance and metastasis. In this review, we examine the differential expression pattern, mechanisms of regulation and contributions made by each PKD isoform to the development and maintenance of invasive breast cancer. In addition, we discuss the potential therapeutic approaches for targeting PKD in this disease.

IRF6 Is Involved in the Regulation of Cell Proliferation and Transformation in MCF10A Cells Downstream of Notch Signaling.

IRF6, a member of Interferon Regulatory Factors (IRF) family, is involved in orofacial and epidermal development. In breast cancer cell lines ectopic expression of IRF6 reduces cell numbers suggesting a role as negative regulator of cell cycle. IRF6 is a direct target of canonical Notch signaling in keratinocyte differentiation. Notch is involved in luminal cell fate determination and stem cell regulation in the normal breast and is implicated as an oncogene in breast cancer. Notch activation is sufficient to induce proliferation and transformation in non-tumorigenic breast epithelial cell line, MCF10A. ΔNp63, which is downregulated by Notch activation in the breast, regulates IRF6 expression in keratinocytes. In this report, we investigate Notch-IRF6 and ΔNp63-IRF6 interactions in MCF10A and MDA MB 231 cells. We observed that in these cells, IRF6 expression is partially regulated by canonical Notch signaling and ΔNp63 downregulation. Furthermore, we demonstrate that IRF6 abrogation impairs Notch-induced proliferation and transformation in MCF10A cells. Thus, we confirm the previous findings by showing a tissue independent regulation of IRF6 by Notch signaling, and extend them by proposing a context dependent role for IRF6, which acts as a positive regulator of proliferation and transformation in MCF10A cells downstream of Notch signaling.

P21 Waf1 is required for complete oncogenic transformation of mouse embryo fibroblasts by E1Aad5 and c-Ha-ras oncogenes

Cyclin-dependent kinase inhibitor p21 Waf1 is known to have alternative functions associated with positive regulation of proliferation, actin cytoskeleton remodeling and suppression of apoptosis. The goal of the present study was to assess the role of p21 Waf1 in the establishment of the transformed phenotype of mouse embryo fibroblasts with stable expression of E1Aad5 and c-Ha-ras complementary oncogenes. Herein, we demonstrate that E1A/c-Ha-Ras-transformed p21 Waf1-null fibroblasts possess some characteristic features of transformed cells, such as loss of contact inhibition, high saturation density, shortened cell cycle, inability to undergo cell-cycle arrest after DNA damage and serum deprivation, but, at the same time, they are not completely transformed in that they are unable to proliferate at clonal density, are anchorage-dependent, retain a fibroblast-like morphology with pronounced actin cytoskeleton and show reduced migration and invasion. Our data support the concept of p21 Waf1 “tumor suppressor” having alternative oncogenic functions in the cytoplasm and for the first time indicate that p21 Waf1 can be indispensable for complete oncogenic transformation.

Functional phosphoproteomic analysis reveals cold-shock domain protein A to be a Bcr-Abl effector-regulating proliferation and transformation in chronic myeloid leukemia

One proposed strategy to suppress the proliferation of imatinib-resistant cells in chronic myeloid leukemia (CML) is to inhibit key proteins downstream of Bcr-Abl. The PI3K/Akt pathway is activated by Bcr-Abl and is specifically required for the growth of CML cells. To identify targets of this pathway, we undertook a proteomic screen and identified several proteins that differentially bind 14-3-3, dependent on Bcr-Abl kinase activity. An siRNA screen of candidates selected by bioinformatics analysis reveals cold-shock domain protein A (CSDA), shown previously to regulate cell cycle progression in epithelial cells, to be a positive regulator of proliferation in a CML cell line. We show that Akt can phosphorylate the serine 134 residue of CSDA but, downstream of Bcr-Abl activity, this modification is mediated through the activation of MEK/p90 ribosomal S6 kinase (RSK) signaling. Inhibition of RSK, similarly to treatment with imatinib, blocked proliferation specifically in Bcr-Abl-positive leukemia cell lines, as well as cells from CML patients. Furthermore, these primary CML cells showed an increase in CSDA phosphorylation. Expression of a CSDA phospho-deficient mutant resulted in the decrease of Bcr-Abl-dependent transformation in Rat1 cells. Our results support a model whereby phosphorylation of CSDA downstream of Bcr-Abl enhances proliferation in CML cells to drive leukemogenesis.

Normal Proliferation and Tumorigenesis but Impaired Pancreatic Function in Mice Lacking the Cell Cycle Regulator Sei1

Sei1 is a positive regulator of proliferation that promotes the assembly of Cdk4-cyclin D complexes and enhances the transcriptional activity of E2f1. The potential oncogenic role of Sei1 is further suggested by its overexpression in various types of human cancers. To study the role of Sei1, we have generated a mouse line deficient for this gene. Sei1-null fibroblasts did not show abnormalities regarding proliferation or susceptibility to neoplastic transformation, nor did we observe defects on Cdk4 complexes or E2f activity. Sei1-null mice were viable, did not present overt pathologies, had a normal lifespan, and had a normal susceptibility to spontaneous and chemically-induced cancer. Pancreatic insulin-producing cells are known to be particularly sensitive to Cdk4-cyclin D and E2f activities, and we have observed that Sei1 is highly expressed in pancreatic islets compared to other tissues. Interestingly, Sei1-null mice present lower number of islets, decreased β-cell area, impaired insulin secretion, and glucose intolerance. These defects were associated to nuclear accumulation of the cell-cycle inhibitors p21Cip1 and p27Kip1 in islet cells. We conclude that Sei1 plays an important role in pancreatic β-cells, which supports a functional link between Sei1 and the core cell cycle regulators specifically in the context of the pancreas.

Phospho-Ablated Id2 Is Growth Suppressive and Pro-Apoptotic in Proliferating Myoblasts

Inhibitor of differentiation protein-2 (Id2) is a dominant negative helix-loop-helix (HLH) protein, and a positive regulator of proliferation, in various cells. The N-terminal region of Id2 contains a consensus cdk2 phosphorylation sequence SPVR, which may be involved with the induction of apoptosis, at least in myeloid 32d.3 cells. However, the role of Id2 phosphorylation at serine 5 in skeletal muscle cells is unknown. The objective of this study was to determine if the phosphorylation of Id2 at serine 5 alters its cellular localization and its role in apoptosis in C2C12 myoblasts. Overexpression of wild type Id2 decreased MyoD protein expression, which corresponded to the increased binding of Id2 to basic HLH proteins E47 and E12. Bromodeoxyuridine incorporation was significantly decreased by the overexpression of phospho-ablated Id2 (S5A); conversely, overexpression of wild type Id2 increased cellular proliferation. The subcellular localization of Id2 and phospho-mimicking Id2 (S5D) were predominantly nuclear compared to S5A. The decreased nuclear localization of S5A corresponded to a decrease in cellular proliferation, and an increase in apoptosis. These data suggest that unphosphorylated Id2 is primarily localized in the cytosol, where it is growth suppressive and potentially pro-apoptotic. These results imply that reducing unphosphorylated Id2 may improve the pool of myoblasts available for differentiation by increasing proliferation and inhibiting apoptosis.

CaMKII-δ Isoform Regulation of Neointima Formation After Vascular Injury

The purpose of this study was to test the function of the calcium/calmodulin-dependent protein kinase II delta2 isoform (CaMKIIdelta2) in regulating vascular smooth muscle (VSM) cell proliferation and migration in response to vascular injury. CaMKII isoform content was assessed in rat carotid arteries after balloon angioplasty-induced injury by Western blotting with isoform specific antibodies. Within 3 days after injury, a significant increase in CaMKIIdelta2 and decrease in CaMKIIgamma isoform content was observed in both medial smooth muscle and adventitial fibroblasts. Neointimal VSM cells expressed primarily the delta2 isoform. Incubation of the injured vessel with adenovirus encoding siRNA targeting CaMKIIdelta isoforms prevented upregulation of the delta2 isoform in the media and adventitia; inhibited cell proliferation assessed by PCNA expression in both layers and markedly inhibited neointima formation and adventitial thickening. CaMKIIdelta2 is specifically induced in VSM and adventitial fibroblasts during the response of an artery to injury and is a positive regulator of proliferation and migration in the vessel wall contributing to neointima formation and vascular remodeling. This provides a potential mechanism for Ca2+-dependent regulation of VSM and myofibroblast proliferation and migration in response to vascular injury or disease.

Gene Expression Profiling of Day 7 Erythroblasts from RARS Before and after Treatment with G-CSF.

Refractory Anemia with Ringed Sideroblasts (RARS) is characterized by severe ineffective erythropoesis, cytochrome c release, and mitochondrial iron overload. (Tehranchi, 2003). Granulocyte-CSF inhibit erythroid apoptosis in vitro as well as in vivo (Tehranchi 2005) The molecular mechanisms underlying the erythroid apoptosis in RARS and the effects of G-CSF were studied by gene expression profiling of erythroblasts from 8 healthy controls and 6 RARS patients. CD34+ selected marrow cells were cultured for 7 days in Iscove's medium with 15% BIT9500. At day 7 an aliquot of RARS cells were treated with G-CSF (100ng/ml) for 4 hours. The gene expression profiles were determined using Affymetrix, U133 Plus2.0 chips (Pellagatti, 2006). Statistical analysis showed that 1426 probe-sets were significantly differentially expressed (P<0.01) between untreated and G-CSF treated RARS samples, and healthy controls. Hierarchical clustering separated these groups into distinct clusters. 22 genes were significantly up-regulated by ≥2-fold in all RARS samples and included CCND2, DLK1, PPM1A and TBC1D8. 35 genes were significantly down-regulated by ≥2-fold, including LRIG1, ABCB7 and MLL3. RARS erythroblasts showed dysregulation of several genes involved in proliferation, apoptosis and iron transport. For instance CCND2 and TBC1D8, positive regulators of proliferation, were up-regulated in RARS, whereas LRIG1, a negative regulator of proliferation, was down-regulated. PPM1A, whose function leads to G2/M cell cycle arrest and apoptosis via p53 activation, was also up-regulated. ABCB7, involved in the transfer of iron from mitochondria to cytosol and in maturation of cytosolic Fe/S enzymes, and mutated in X-linked sideroblastic anemia with ataxia, was significantly down-regulated in RARS. Several dysregulated genes in RARS were restored to the range of normal expression after G-CSF treatment. Of these, MFN2, which was down-regulated in RARS, maintains mitochondrial membrane stability, and restores mitochondrial membrane potential and cell respiration. A normalization of MFN2 is thus consistent with the observed inhibitory effect on cytochrome c release.Several dysregulated genes including BAX, FLIP and BAG1 were not altered by G-CSF treatment, indicating that G-CSF does not exert an unspecific anti-apoptotic effect through the Bcl2 family proteins. Only one, BCLAF1, a transcriptional repressor and pro-apoptotic member of BCL2 family was upregulated in RARS erythroblasts and down-regulated by G-CSF. G-CSF treatment down-regulated also the expression of interferon induced genes including IFIT1, IFIH1, IFI44, IFIT2, IFIT3, IRF7, IFRG28 and IFI78, several of which were previously shown to be upregulated in RARS CD34+ cells (Pellagatti, 2006). Since G-CSF specifically supports erythroblast survival in RARS through inhibition of mitochondria-mediated apoptosis, our findings may lead to further understanding of the molecular mechanisms in RARS and to the identification of candidate genes in this disease. [Display omitted]

Sex Hormone-binding Globulin Selectively Modulates Estradiol-regulated Genes in MCF-7 Cells

Human sex hormone-binding globulin inhibits the effects of estradiol on proliferation and apoptosis of breast cancer cells. We report here the effect of sex hormone-binding globulin on estradiol regulation of gene expression in MCF-7 breast cancer cells using a selected set of genes. Estradiol upregulates genes that are positive regulators of proliferation (e.g., bcl-2, c-fos, c-myc, cyclin D) or/and related to more aggressive form of breast cancer (e.g. BRCA-1, EGF-R) and downregulates two genes (c-jun and ERalpha). Sex hormone-binding globulin modulates only a selected group of estradiol-controlled genes (inhibiting upregulation of bcl-2, c-myc, EGF-R, PR, and downregulation of ERalpha), starting 48 hours after treatment. Our study demonstrates that in breast cancer cells, sex hormone-binding globulin is effective on few selected genes which are involved in cell growth and apoptosis or related to cell estrogen-dependence and that the protein regulation of estradiol effect is selected and specific. Sex hormone-binding globulin action in estrogen breast cancer cells is strongly associated to cell growth and estrogen-sensitivity.

Ovol1 represses its own transcription by competing with transcription activator c-Myb and by recruiting histone deacetylase activity

Ovol1 belongs to a family of evolutionarily conserved zinc finger proteins that act downstream of key developmental signaling pathways such as Wnt and TGF-β/BMP. It plays important roles in epithelial and germ cell development, particularly by repressing c-Myc and Id2 genes and modulating the balance between proliferation and differentiation of progenitor cells. In this study, we show that Ovol1 negatively regulates its own expression by binding to and repressing the activity of its promoter. We further demonstrate that Ovol1 uses both passive and active repression mechanisms to auto-repress: (1) it antagonizes transcriptional activation of c-Myb, a known positive regulator of proliferation, by competing for DNA binding; (2) it recruits histone deacetylase activity to the promoter via an N-terminal SNAG repressor domain. At Ovol1 cognate sites in the endogenous Ovol1 promoter, c-Myb binding correlates with increased histone acetylation, whereas the expression of Ovol1 correlates with a displacement of c-Myb from the DNA and decreased histone acetylation. Collectively, our data suggest that Ovol1 restricts its own expression by counteracting c-Myb activation and histone acetylation of the Ovol1 promoter.

BMP4 Regulates Pancreatic Progenitor Cell Expansion through Id2

Inhibitor of DNA binding (Id) proteins bind to and inhibit the function of basic helix-loop-helix (bHLH) transcription factors including those that regulate pancreatic development. Moreover, bone morphogenetic proteins (BMPs) regulate the expression of Ids. We hypothesized that BMP4 and Id proteins play a role in the expansion and differentiation of epithelial progenitor cells. We demonstrate that BMP4 induces the expression of Id2 along with the expansion of AR42J pancreatic epithelial cells. Furthermore, neutralization of BMP4 significantly reduced duct epithelial cell expansion in a mouse model of islet regeneration. BMP4 stimulation promotes Id2 binding to the bHLH transcription factor NeuroD, which is required for the differentiation of pancreatic islet cells. Therefore, our results indicate that BMP4 stimulation blocks the differentiation of endocrine progenitor cells and instead promotes their expansion thereby revealing a novel paradigm of signaling explaining the balance between expansion and differentiation of pancreatic duct epithelial progenitors. Understanding the mechanisms of BMP and Id function elucidates a key step during pancreas embryogenesis, which is important knowledge for expanding pancreatic progenitors in vitro.

Overexpression of Id2 Results in a Decrease in MyoD in Proliferating C2C12 Myoblasts

Inhibitor of differentiation protein-2 (Id2) is a dominant negative helix-loop-helix (HLH) protein, and a positive regulator of proliferation, in various cells. Id2 may also have a role in apoptosis, because the N-terminal region induces apoptosis in myeloid 32d.3 cells. Furthermore, elevated levels of Id2 and apoptotic markers have been identified in aged rat skeletal muscles. The role of Id2 in skeletal muscle cells is unknown. PURPOSE Because Id2 is elevated in aged skeletal muscle, the objective of this study was to determine if overexpression of Id2 would alter MyoD levels in proliferating C2C12 myoblasts, a mouse satellite cell line. METHODS The full length Id2 gene was generated by PCR amplification from cDNA of rat hindlimb muscles. Primers with Nde1 and HindIII restrictions sites were used to subclone Id2 into a pDNR-1r Donor Vector that contained two loxP sites. Cre recombinase mediated the transfer of the Id2 fragment located between the two loxP sites of the Id2-pDNR-1r donor vector, to the loxP acceptor vector pLP-IRES2-eGFP to yield Id2-IRES-eGFP. The internal ribosomal entry sequence (IRES) allows both the Id2 gene and the enhanced green fluorescent protein (eGFP) gene to be translated simultaneously from a single bicistronic mRNA. For control experiments, pDNR-1r and Luciferase-pDNR-1r vectors were recombined with the pLP-IRES-eGFP vector to generate pDNR-IRES-eGFP and Luc-IRES-eGFP expression vectors. RESULTS Luciferase activity in Luc-IRES-eGFP transfected cells is significantly (p = 0.0001) higher (81,568-fold increase) compared to the average luciferase activity of C2C12 cells, pDNR-IRES-eGFP and Id2-IRES-eGFP transfected myoblasts. Florescence activated cell sorter (FACS) analysis revealed that Id2 expression is significantly (p > 0.05) elevated (383% & 275%) in Id2-IRES-eGFP transfected C2C12 myoblasts. Id2 expression was significantly (p > 0.05) elevated (383%) in Id2-IRES-eGFP transfected C2C12 myoblasts through western analysis. FACS analysis showed that MyoD expression was significantly (p > 0.05) lower (20%) in C2C12 myoblasts transfected with Id2. There were no significant differences in E47/E12 expression between groups. CONCLUSION These data suggest that the overexpression of Id2 in vitro maybe responsible for the decrease of MyoD, because Id2 has been shown to preferentially bind to Class A basic HLH proteins E47 and E12. This would leave MyoD without a dimerization partner and subject to proteolysis. Supported by NIH R01AG021530

Developmental expression patterns and localization of DNA-binding protein inhibitor (Id3) in the mouse retina

Id3 (inhibitor of DNA binding/differentiation), a member of the Id helix-loop-helix protein family, has long been studied as a positive regulator of proliferation and a negative regulator of differentiation. In this study, we examined the expression pattern and cellular phenotypes of Id3 in postnatal and adult mouse retina. Id3 was mainly expressed in the early postnatal inner retina. From the late postnatal development towards adulthood, Id3 expression was confined to the ganglion cell layer and the inner nuclear layer. Colocalization analysis showed that Id3 positive cells were identified as retinal ganglion cells and amacrine cells. The differential expression profiles of Id3 provide the groundwork for the elucidation of its possible role in retinal development.