Vascular Changes Following Exercise-Induced Hyperthermia

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Purification and properties of an erythrocyte hemoprotein with a unique prosthetic group

1. 1.|A unique hemoprotein has been isolated from a hemolysate of normal human erythrocytes by a procedure which involves (NH4)2SO4 precipitation and chromatography on Amberlite CG-50, DEAE-cellulose, Bio-Gel P-60, and Bio-Gel P-30.2. 2.|The purified hemoprotein appeared homogeneous on ultracentrifugation although small amounts of impurities were detected by polyacrylamide gel electrophoresis. The molecular weight was estimated to be 21 000 by gel filtration. Absorption maxima were located at 416 m[mu] for the oxidized form, 430 m[mu] for the CN- complex of the oxidized form, 434 m[mu] for the reduced form, and 425 m[mu] for the CO derivative of the reduced form. The reduced pyridine hemochrome of the isolated prosthetic group has maxima at 434, 540, and 579 m[mu], clearly indicating that the protein possesses a previously unrecognized heme.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32697/1/0000064.pd

Soluble cytochrome b5 from human erythrocytes

1. A hemeprotein with properties similar to microsomal cytochrome b5 has been detected in the supernatant fraction of hemolysates of human, beef, and rabbit erythrocytes. A method has been developed for determining the amount of this soluble cytochrome in small volumes of blood. The amount of the protein decreases during cell storage at 4 [deg]C. Blood cells rich in reticulocytes contain more of the protein than do mature cells.2. The cytochrome has been purified from human erythrocytes by a procedure which employs chromatography on Amberlite CG-50 and DETE-cellulose, ultrafiltration, and gel filtration. The purified protein sedimented in the ultracentrifuge as a single peak with an s20, w of 1.40. However, minor impurities were detected by polyacrylamide disc electrophoresis.3. The molecular weight of the purified protein has been calculated to be 14600 from sedimentation and diffusion measurements and 18400 as determined by gel filtration. The prosthetic group has been identified as protoheme IX. The spectral properties of the hemeprotein are those of a low spin heme complex. The EPR spectrum of the oxidized form shows g values of 3.03, 2.21, and 1.39 and the visible spectrum has a Soret absorbance maximum at 413 nm. The protein is reducible by dithionite or NADH plus cytochrome b5 reductase and the reduced form shows absorbance maxima at 423, 527, and 556 nm with a shoulder at 560 nm.4. The cytochrome b5 differs from the other B-type cytochrome of erythrocyte, S-protein (hemeprotein 559), and is not derived from this protein. The erythrocyte cytochrome b5 is similar to the cytochrome b5 solubilized from liver microsomes in terms of spectral properties, molecular weight, prosthetic group, and reactivity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34069/1/0000347.pd

CRL4^(AMBRA1) targets Elongin C for ubiquitination and degradation to modulate CRL5 signaling

Multi‐subunit cullin‐RING ligases (CRLs) are the largest family of ubiquitin E3 ligases in humans. CRL activity is tightly regulated to prevent unintended substrate degradation or autocatalytic degradation of CRL subunits. Using a proteomics strategy, we discovered that CRL4^(AMBRA1) (CRL substrate receptor denoted in superscript) targets Elongin C (ELOC), the essential adapter protein of CRL5 complexes, for polyubiquitination and degradation. We showed that the ubiquitin ligase function of CRL4^(AMBRA1) is required to disrupt the assembly and attenuate the ligase activity of human CRL5^(SOCS3) and HIV‐1 CRL5^(VIF) complexes as AMBRA1 depletion leads to hyperactivation of both CRL5 complexes. Moreover, CRL4^(AMBRA1) modulates interleukin‐6/STAT3 signaling and HIV‐1 infectivity that are regulated by CRL5^(SOCS3) and CRL5^(VIF), respectively. Thus, by discovering a substrate of CRL4^(AMBRA1), ELOC, the shared adapter of CRL5 ubiquitin ligases, we uncovered a novel CRL cross‐regulation pathway

A putative antiviral role of plant cytidine deaminases

[EN] Background: A mechanism of innate antiviral immunity operating against viruses infecting mammalian cells has been described during the last decade. Host cytidine deaminases (e.g., APOBEC3 proteins) edit viral genomes, giving rise to hypermutated nonfunctional viruses; consequently, viral fitness is reduced through lethal mutagenesis. By contrast, sub-lethal hypermutagenesis may contribute to virus evolvability by increasing population diversity. To prevent genome editing, some viruses have evolved proteins that mediate APOBEC3 degradation. The model plant Arabidopsis thaliana genome encodes nine cytidine deaminases (AtCDAs), raising the question of whether deamination is an antiviral mechanism in plants as well. Methods: Here we tested the effects of expression of AtCDAs on the pararetrovirus Cauliflower mosaic virus (CaMV). Two different experiments were carried out. First, we transiently overexpressed each one of the nine A. thaliana AtCDA genes in Nicotiana bigelovii plants infected with CaMV, and characterized the resulting mutational spectra, comparing them with those generated under normal conditions. Secondly, we created A. thaliana transgenic plants expressing an artificial microRNA designed to knock-out the expression of up to six AtCDA genes. This and control plants were then infected with CaMV. Virus accumulation and mutational spectra where characterized in both types of plants. Results: We have shown that the A. thaliana AtCDA1 gene product exerts a mutagenic activity, significantly increasing the number of G to A mutations in vivo, with a concomitant reduction in the amount of CaMV genomes accumulated. Furthermore, the magnitude of this mutagenic effect on CaMV accumulation is positively correlated with the level of AtCDA1 mRNA expression in the plant. Conclusions: Our results suggest that deamination of viral genomes may also work as an antiviral mechanism in plants.This work was supported by the former Spanish Ministerio de Ciencia e Innovación-FEDER grant BFU2009-06993 to SFE. JMC was supported by the CSIC JAE-doc program/Fondo Social Europeo. AG-P was supported by a grant for Scientific and Technical Activities and by grant P10-CVI-65651, both from Junta de Andalucía.Martín, S.; Cuevas, J.; Grande-Perez, A.; Elena Fito, SF. (2017). A putative antiviral role of plant cytidine deaminases. F1000Research. 1-14. https://doi.org/10.12688/f1000research.11111.2S11

The earliest thymic T cell progenitors sustain B cell and myeloid lineage potential

The stepwise commitment from hematopoietic stem cells in the bone marrow to T lymphocyte-restricted progenitors in the thymus represents a paradigm for understanding the requirement for distinct extrinsic cues during different stages of lineage restriction from multipotent to lineage-restricted progenitors. However, the commitment stage at which progenitors migrate from the bone marrow to the thymus remains unclear. Here we provide functional and molecular evidence at the single-cell level that the earliest progenitors in the neonatal thymus had combined granulocyte-monocyte, T lymphocyte and B lymphocyte lineage potential but not megakaryocyte-erythroid lineage potential. These potentials were identical to those of candidate thymus-seeding progenitors in the bone marrow, which were closely related at the molecular level. Our findings establish the distinct lineage-restriction stage at which the T cell lineage-commitment process transits from the bone marrow to the remote thymus. © 2012 Nature America, Inc. All rights reserved

CRL4^(AMBRA1) targets Elongin C for ubiquitination and degradation to modulate CRL5 signaling

Multi‐subunit cullin‐RING ligases (CRLs) are the largest family of ubiquitin E3 ligases in humans. CRL activity is tightly regulated to prevent unintended substrate degradation or autocatalytic degradation of CRL subunits. Using a proteomics strategy, we discovered that CRL4^(AMBRA1) (CRL substrate receptor denoted in superscript) targets Elongin C (ELOC), the essential adapter protein of CRL5 complexes, for polyubiquitination and degradation. We showed that the ubiquitin ligase function of CRL4^(AMBRA1) is required to disrupt the assembly and attenuate the ligase activity of human CRL5^(SOCS3) and HIV‐1 CRL5^(VIF) complexes as AMBRA1 depletion leads to hyperactivation of both CRL5 complexes. Moreover, CRL4^(AMBRA1) modulates interleukin‐6/STAT3 signaling and HIV‐1 infectivity that are regulated by CRL5^(SOCS3) and CRL5^(VIF), respectively. Thus, by discovering a substrate of CRL4^(AMBRA1), ELOC, the shared adapter of CRL5 ubiquitin ligases, we uncovered a novel CRL cross‐regulation pathway