Chronic granulomatous disease (CGD) is a recessive disorder characterized by a defective phagocyte respiratory burst oxidase, life-threatening pyogenic infections and inflammatory granulomas. Gene ...targeting was used to generate mice with a null allele of the gene involved in X-linked CGD, which encodes the 91 kD subunit of the oxidase cytochrome b. Affected hemizygous male mice lacked phagocyte superoxide production, manifested an increased susceptibility to infection with Staphylococcus aureus and Aspergillus fumigatus and had an altered inflammatory response in thioglycollate peritonitis. This animal model should aid in developing new treatments for CGD and in evaluating the role of phagocyte-derived oxidants in inflammation.
There is a need for more convenient, less frequent treatment to help address challenges associated with daily oral HIV treatment in people living with HIV, including stigma, pill burden, drug-food ...interactions, and adherence. The phase 3 ATLAS and FLAIR studies showed non-inferiority of long-acting cabotegravir and rilpivirine dosed every 4 weeks compared with standard oral therapy for the maintenance of virological suppression in adults with HIV-1 over 48 weeks. We present the 96-week findings.
FLAIR is a randomised, phase 3, open-label, multicentre study done in 11 countries investigating whether switching to long-acting cabotegravir and rilpivirine is non-inferior to daily dolutegravir, abacavir, and lamivudine in virologically suppressed adults living with HIV-1. Antiretroviral therapy (ART)-naive participants received induction therapy with daily oral dolutegravir (50 mg), abacavir (600 mg), and lamivudine (300 mg) for 20 weeks. After 16 weeks, participants with less than 50 HIV-1 RNA copies per mL were randomly assigned (1:1) to continue the standard of care regimen (standard care group) or switch to receive daily oral cabotegravir 30 mg and rilpivirine 25 mg for at least 4 weeks followed by long-acting cabotegravir 400 mg and rilpivirine 600 mg, administered as two 2 mL intramuscular injections, every 4 weeks for at least 96 weeks (long-acting group). Randomisation was stratified by baseline (preinduction) HIV-1 RNA (<100 000 or ≥100 000 copies per mL) and sex at birth and used GlaxoSmithKline-verified randomisation software (RandAll NG, version 1.3.3) for treatment assignment. The primary endpoint was the proportion of participants with plasma HIV-1 RNA of 50 copies per mL or more assessed as per the US Food and Drug Administration (FDA) Snapshot algorithm at week 48, which has been reported previously. Here, we report the proportion of participants with 50 or more HIV-1 RNA copies per mL using the FDA Snapshot algorithm at week 96 (intention-to-treat population; non-inferiority margin 6%). The trial is registered with ClinicalTrials.gov, NCT02938520.
Between Oct 27, 2016, and March 24, 2017, 809 participants were screened. 631 (78%) participants entered the induction phase and 566 (70%) were randomly assigned to either the standard care group (283 50% participants) or the long-acting group (283 50%). Median age was 34 years (IQR 29 to 43), 62 (11%) were 50 years or older, 127 (22%) were women (sex at birth), and 419 (74%) were white. At week 96, nine (3%) participants in each arm had 50 or more HIV-1 RNA copies per mL, with an adjusted difference of 0·0 (95% CI -2·9 to 2·9), consistent with non-inferiority established at week 48. Across both treatment groups, adverse events leading to withdrawal were infrequent (14 5% participants in the long-acting group and four 1% in the standard care group). Injection site reactions were the most common adverse event, reported by 245 (88%) participants in the long-acting group; their frequency decreased over time. Median injection site reaction duration was 3 days (IQR 2 to 4), and 3082 (99%) of 3100 reactions were grade 1 or 2. No deaths occurred during the maintenance phase.
The 96-week results reaffirm the 48-week results, showing long-acting cabotegravir and rilpivirine continued to be non-inferior compared with continuing a standard care regimen in adults with HIV-1 for the maintenance of viral suppression. These results support the durability of long-acting cabotegravir and rilpivirine, over an almost 2-year-long period, as a therapeutic option for virally suppressed adults with HIV-1.
ViiV Healthcare and Janssen Research and Development.
The transcription factor SCL/tal-1 is essential for blood cell development. Though it is also expressed in vascular endothelium, SCL has been considered dispensable for vessel formation. Through ...transgenic rescue of hematopoietic defects of SCL-/- embryos and analysis of chimeras generated with SCL-/- ES cells tagged with a transgene expressed in vascular endothelial cells, we show that SCL is essential for angiogenic remodeling of the yolk sac capillary network into complex vitelline vessels. These findings establish a role for SCL in embryonic angiogenesis and argue for critical functions in both embryonic blood and vascular cells, the descendents of the presumptive hemangioblast.
Suggestions that the field of hemoglobin regulation and erythroid cell molecular biology was undergoing a tortuous and slow death, awash in the scientific community several years ago, were dispelled ...by the findings presented at the Seventh Conference on Hemoglobin Switching. After a phase in which neither the cis-elements nor trans-factors important for globin and erythroid gene expression were evident, recent progress has been rapid. Once again, studies in this area are providing fundamental insights into eukaryotic biology. The long-distance influence of LCR elements on chromatin structure and gene expression is remarkable and likely to be encountered in the analysis of other developmentally regulated, multigene loci. How LCR elements influence chromatin structure and maintain an open configuration is a problem at the core of gene regulation. We can be optimistic that further dissection of LCRs will delineate DNA sequences critical for these effects and associated proteins. The interaction of LCRs with individual genes must depend on specific protein-protein interactions, most likely involving a small, but elite, group of regulators. At least one critical transcriptional regulator of erythroid-expressed genes, GATA-1, is firmly established. Others are being pursued. The mechanisms by which they collaborate with each other should provide the missing pieces to the puzzle of cell-specific gene expression in the erythroid lineage. As the phenomenology of Hb switching is mimicked in transgenic mice, the elements mediating competitive and non-competitive (or autonomous) modes of regulation will be systematically delineated. Whether knowledge of the cis- and trans- components involved in switching will lead to the development of therapeutic approaches aimed at altering their complex interactions is uncertain. Fortunately, recent progress in hematopoietic stem cell biology once again raises hopes that gene transfer strategies for management of hemoglobin disorders may be more than a distant, impractical goal.
The hematopoietic system develops during embryogenesis at temporally and anatomically restricted sites. The anatomical origin of definitive HSCs is not fully resolved, and little is known about how ...the different fetal hematopoietic microenvironments direct HSC development. Here, we show that the mouse placenta functions as a hematopoietic organ that harbors a large pool of pluripotent HSCs during midgestation. The onset of HSC activity in the placenta parallels that of the AGM (aorta-gonad-mesonephros) region starting at E10.5–E11.0. However, the placental HSC pool expands until E12.5–E13.5 and contains >15-fold more HSCs than the AGM. The expansion of the CD34
+c-kit
+ HSC pool in the placenta occurs prior to and during the initial expansion of HSCs in the fetal liver. Importantly, the placental HSC pool is not explained by rare circulating HSCs, which appear later. These data support an important, but unappreciated, role for the placenta in establishing the mammalian definitive hematopoietic system.
Previous work has demonstrated that lineage-specific transcription factors play essential roles in red blood cell development. More recent studies have shown that these factors participate in ...critical protein-protein interactions in addition to binding DNA. The zinc finger transcription factor GATA-1, a central mediator of erythroid gene expression, interacts with multiple proteins including FOG-1, EKLF, SP1, CBP/p300 and PU.1. The mechanisms by which these interactions influence GATA-1 function, as well as any possible relationships between these seemingly disparate complexes, remain incompletely understood. However, several new findings have provided further insight into the functional significance of some of these interactions. Studies involving point mutants of GATA-1 have shown that a direct physical interaction between GATA-1 and FOG-1 is essential for normal human erythroid and megakaryocyte maturation in vivo. In addition, evidence has emerged that physical interaction between GATA-1 and the myeloid/lymphoid specific factor PU.1, an oncogene implicated in murine erythroleukemia, acts to functionally cross-antagonize one another. This provides a possible mechanism by which dysregulated expression of hematopoietic transcription factors leads to lineage maturation arrest in leukemias.
The lineage-specific transcription factors GATA-1 and PU.1 can physically interact to inhibit each other's function, but the mechanism of repression of GATA-1 function by PU.1 has not been ...elucidated. Both the N terminus and the C terminus of PU.1 can physically interact with the C-terminal zinc finger of GATA-1. It is demonstrated that the PU.1 N terminus, but not the C terminus, is required for inhibiting GATA-1 function. Induced overexpression of PU.1 in K562 erythroleukemia cells blocks hemin-induced erythroid differentiation. In this system, PU.1 does not affect the expression of GATA-1 messenger RNA, protein, or nuclear localization. However, GATA-1 DNA binding decreases dramatically. By means of electrophoretic mobility shift assays with purified proteins, it is demonstrated that the N-terminal 70 amino acids of PU.1 can specifically block GATA-1 DNA binding. In addition, PU.1 had a similar effect in the G1ER cell line, in which the GATA-1 null erythroid cell line G1E has been transduced with a GATA-1–estrogen receptor fusion gene, which is directly dependent on induction of the GATA-1 fusion protein to effect erythroid maturation. Consistent with in vitro binding assays, overexpression of PU.1 blocked DNA binding of the GATA-1 fusion protein as well as GATA-1–mediated erythroid differentiation of these G1ER cells. These results demonstrate a novel mechanism by which function of a lineage-specific transcription factor is inhibited by another lineage-restricted factor through direct protein–protein interactions. These findings contribute to understanding how protein–protein interactions participate in hematopoietic differentiation and leukemogenesis.
Stem cell alchemy Orkin, Stuart H
Nature medicine,
11/2000, Letnik:
6, Številka:
11
Journal Article
Recenzirano
The extraordinary plasticity of tissue stem cells, such as the ability of blood stem cells to differentiate into liver, would intrigue even the ancient alchemists. Recent discoveries also force us to ...rethink cell lineage relationships and expand the potential for cell-based therapies.
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