POGZ Is Required for Silencing Mouse Embryonic β-like Hemoglobin and Human Fetal Hemoglobin Expression

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked FilesFetal globin genes are transcriptionally silenced during embryogenesis through hemoglobin switching. Strategies to derepress fetal globin expression in the adult could alleviate symptoms in sickle cell disease and β-thalassemia. We identified a zinc-finger protein, pogo transposable element with zinc-finger domain (POGZ), expressed in hematopoietic progenitor cells. Targeted deletion of Pogz in adult hematopoietic cells in vivo results in persistence of embryonic β-like globin expression without affecting erythroid development. POGZ binds to the Bcl11a promoter and erythroid-specific intragenic regulatory regions. Pogz+/- mice show elevated embryonic β-like globin expression, suggesting that partial reduction of Pogz expression results in persistence of embryonic β-like globin expression. Knockdown of POGZ in primary human CD34+ progenitor cell-derived erythroblasts reduces BCL11A expression, a known repressor of embryonic β-like globin expression, and increases fetal hemoglobin expression. These findings are significant, since new therapeutic targets and strategies are needed to treat β-globin disorders.Frederick National Laboratory for Cancer Research, NIH intramural research program of the NHLBI, NIH intramural research program of the NIDDK, NIH USUH

Human cystatin C expression and regulation by TGF-β1: Implications for the pathogenesis of hereditary cystatin C amyloid angiopathy causing brain hemorrhage

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldCystatin C amyloid (ACys) deposition in arteries of the brain is the primary cause of cerebral hemorrhage in hereditary cystatin C amyloid angiopathy (HCCAA). A missense mutation (codon 68; Leu 68 → Gln 68) in the human cystatin C gene renders cystatin C amyloidogenic and in addition leads to a significant reduction in the concentration of cystatin C in the cerebrospinal fluid. We show that the mutation does not affect the accumulation of cystatin C mRNA in monocytes of affected individuals. Further studies on tissue and cellular distribution of cystatin C mRNA reveal an ubiquitous expression of the molecule. However, these levels vary as much as 13 fold between different tissues, with highest expression levels in pancreas, testis and brain. Results are then presented showing that monocytes exposed to transforming growth factor beta 1 (TGF-β1) exhibit a several fold increase in the expression of cystatin C mRNA and cystatin Cprotein. Here, TGF-β1 stimulates secretion of cystatin C from normal monocytes whilst, in contrast, secretion of cystatin C from Leu 68/Gln 68 monocytes is markedly impaired. It is suggested that TGF-β1 is an effector molecule in acute and local phase regulation of cystatin C to prevent damage of cells and matrix by cysteine proteases. We postulate that synergism between ACys and deficiency of cystatin C, in the amyloid-involved areas, contributes to a more aggressive form of vascular damage and consequently earlier onset of cerebral hemorrhag

Gene expression analysis of hematopoietic progenitor cells identifies Dlg7 as a potential stem cell gene

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldInducible hematopoietic stem/progenitor cell lines represent a model for studying genes involved in self-renewal and differentiation. Here, gene expression was studied in the inducible human CD34+ acute myelogenous leukemia cell line KG1 using oligonucleotide arrays and suppression subtractive cloning. Using this approach, we identified Dlg7, the homolog of the Drosophila Dlg1 tumor suppressor gene, as downregulated at the early stages of KG1 differentiation. Similarly, Dlg7 was expressed in normal purified umbilical cord blood CD34+CD38- progenitors but not in the more committed CD34+CD38+ population. Dlg7 expression was not detected in differentiated cells obtained from hematopoietic colonies, nor was expression detected in purified T-cells, B-cells, and monocytes. When analyzed in different types of stem cells, Dlg7 expression was detected in purified human bone marrow-derived CD133+ progenitor cells, human mesenchymal stem cells, and mouse embryonic stem (ES) cells. Overexpression of Dlg7 in mouse ES cells increased their growth rate and reduced the number of EBs emerging upon differentiation. In addition, the EBs were significantly smaller, indicating an inhibition in differentiation. This inhibition was further supported by higher expression of Bmp4, Oct4, Rex1, and Nanog in EBs overexpressing Dlg7 and lower expression of Brachyury. Finally, the Dlg7 protein was detected in liver and colon carcinoma tumors but not in normal adjacent tissues, suggesting a role for the gene in carcinogenesis. In conclusion, our results suggest that Dlg7 has a role in stem cell survival, in maintaining stem cell properties, and in carcinogenesis. Disclosure of potential conflicts of interest is found at the end of this article

Association of vitamin D binding protein variants with chronic mucus hypersecretion in Iceland

BACKGROUND: Previous studies of vitamin D binding protein (VDBP, also known as group-specific component, Gc, encoded by the GC gene) have implicated two gene variants, GC*2 and GC*1F, as possible contributors with chronic obstructive pulmonary disease (COPD) protection and susceptibility, respectively. The objective of this study was to examine the association of VDBP to different subtypes of COPD. STUDY DESIGN: The association of the various GC genotypes to the COPD phenotype was examined in Icelandic COPD patients who were followed by pulmonary physicians at the University Hospital of Iceland. METHODS: All patients were genotyped for the known alleles of the GC gene. The single nucleotide polymorphisms (SNPs) were identified by a restriction fragment length polymorphism procedure. Study power was estimated based on allele frequencies of the variants, and risk ratios were calculated from the prevalence of genotypes in the affected group divided by its prevalence in the control population. Statistical analyses were performed using the 2-tailed Fisher's Exact Test and chi(2) test, where appropriate. PATIENT GROUP: One hundred and two COPD patients and 183 controls, together with 46 asthma patients and 48 patients with chronic mucous hypersecretion (CMH) were examined. MAIN OUTCOME MEASURE AND RESULTS: The results demonstrate similar allele and genotype frequencies of GC in COPD patients overall and healthy controls. However, there was a higher prevalence of genotypes carrying a GC*1F allele and lower prevalence of genotypes with a GC*2 allele in the CMH patients than in controls. This difference was most notable in the homozygous form: 8.3% vs 1.1% for the GC*1F/*1F, and 0.0% vs 7.6% for the GC*2/*2 genotypes, respectively. When controlled for smoking, only the non-smoking CMH patients demonstrated a significantly altered frequency of the GC*1F/*1F genotype (p = 0.0001). The prevalence of the GC*2/*2 genotype was also significantly lower in patients with bronchial hypersecretion with airflow obstruction compared with the control group (2.9% vs 7.6%). Taken together, these results demonstrate that the GC*1F and GC*2 alleles are associated with sputum hypersecretion in individuals who are at increased risk of developing COPD