| 7951. |
- Brattsand, Maria, et al.
(författare)
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Purification, molecular cloning, and expression of a human stratum corneum trypsin-like serine protease with possible function in desquamation
- 1999
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Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 274:42, s. 30033-40
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Tidskriftsartikel (refereegranskat)abstract
- A new human 33-kDa serine protease was purified from human epidermis, and its cDNA was cloned from a keratinocyte library, from mRNA from a human keratinocyte line (HaCat) and from mRNA from human skin. Polyclonal antibodies specific for the new protein detected three groups of proteins in partially purified extracts of cornified eptihelium of human plantar skin. The three components are proposed to correspond to proenzyme, active enzyme, and proteolytically modified active enzyme. After N-deglycosylation, there was a decrease in apparent molecular mass of all detected components. Expression of the cloned cDNA in a eukaryotic virus-derived system yielded a recombinant protein that could be converted to an active protease by treatment with trypsin. Polymerase chain reaction analyses of cDNA from a number of human tissues showed high expression of the new enzyme in the skin and low expression in brain, placenta, and kidney. Homology searches yielded the highest score for porcine enamel matrix protease (55% amino acid sequence homology). High scores were also obtained for human and mouse neuropsin and for human stratum corneum chymotryptic enzyme. The function of this new protease, tentatively named stratum corneum tryptic enzyme, may be related to stratum corneum turnover and desquamation in the epidermis.
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| 7952. |
- Braumann, Ilka, et al.
(författare)
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Reduced chlorophyll biosynthesis in heterozygous barley magnesium chelatase mutants
- 2014
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Ingår i: Plant Physiology and Biochemistry. - : Elsevier BV. - 1873-2690 .- 0981-9428. ; 78, s. 10-14
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Tidskriftsartikel (refereegranskat)abstract
- Chlorophyll biosynthesis is initiated by magnesium chelatase, an enzyme composed of three proteins, which catalyzes the insertion of Mg2+ into protoporphyrin IX to produce Mg-protoporphyrin IX. In barley (Hordeum vulgare L.) the three proteins are encoded by Xantha-f, Xantha-g and Xantha-h. Two of the gene products, XanH and XanG, belong to the structurally conserved family of AAA+ proteins (ATPases associated with various cellular activities) and form a complex involving six subunits of each protein. The complex functions as an ATP-fueled motor of the magnesium chelatase that uses XanF as substrate, which is the catalytic subunit responsible for the insertion of Mg2+ into protoporphyrin IX. Previous studies have shown that semi-dominant Xantha-h mutations result in non-functional XanH subunits that participate in the formation of inactive AAA complexes. In the present study, we identify severe mutations in the barley mutants xantha-h.38, -h.56 and -h.57. A truncated form of the protein is seen in xantha-h.38, whereas no XanH is detected in xantha-h.56 and -h.57. Heterozygous mutants show a reduction in chlorophyll content by 14-18% suggesting a slight semi-dominance of xantha-h.38, -h.56 and -h.57, which otherwise have been regarded as recessive mutations
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| 7953. |
- Braun, Gabriel A., et al.
(författare)
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On the Mechanism of Self-Assembly by a Hydrogel-Forming Peptide
- 2020
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 21:12, s. 4781-4794
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Tidskriftsartikel (refereegranskat)abstract
- Self-assembling peptide-based hydrogels are a class of tunable soft materials that have been shown to be highly useful for a number of biomedical applications. The dynamic formation of the supramolecular fibrils that compose these materials has heretofore remained poorly characterized. A better understanding of this process would provide important insights into the behavior of these systems and could aid in the rational design of new peptide hydrogels. Here, we report the determination of the microscopic steps that underpin the self-assembly of a hydrogel-forming peptide, SgI37-49. Using theoretical models of linear polymerization to analyze the kinetic self-assembly data, we show that SgI37-49 fibril formation is driven by fibril-catalyzed secondary nucleation and that all the microscopic processes involved in SgI37-49 self-assembly display an enzyme-like saturation behavior. Moreover, this analysis allows us to quantify the rates of the underlying processes at different peptide concentrations and to calculate the time evolution of these reaction rates over the time course of self-assembly. We demonstrate here a new mechanistic approach for the study of self-assembling hydrogel-forming peptides, which is complementary to commonly used materials science characterization techniques.
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| 7954. |
- Breakell, T., et al.
(författare)
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Obinutuzumab-Induced B Cell Depletion Reduces Spinal Cord Pathology in a CD20 Double Transgenic Mouse Model of Multiple Sclerosis
- 2020
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1422-0067. ; 21:18
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Tidskriftsartikel (refereegranskat)abstract
- B cell-depleting therapies have recently proven to be clinically highly successful in the treatment of multiple sclerosis (MS). This study aimed to determine the effects of the novel type II anti-human CD20 (huCD20) monoclonal antibody (mAb) obinutuzumab (OBZ) on spinal cord degeneration in a B cell-dependent mouse model of MS. Double transgenic huCD20xHIGR3 (CD20dbtg) mice, which express human CD20, were immunised with the myelin fusion protein MP4 to induce experimental autoimmune encephalomyelitis (EAE). Both light and electron microscopy were used to assess myelination and axonal pathology in mice treated with OBZ during chronic EAE. Furthermore, the effects of the already established murine anti-CD20 antibody 18B12 were assessed in C57BL/6 wild-type (wt) mice. In both models (18B12/wt and OBZ/CD20dbtg) anti-CD20 treatment significantly diminished the extent of spinal cord pathology. While 18B12 treatment mainly reduced the extent of axonal pathology, a significant decrease in demyelination and increase in remyelination were additionally observed in OBZ-treated mice. Hence, the data suggest that OBZ could have neuroprotective effects on the CNS, setting the drug apart from the currently available type I anti-CD20 antibodies.
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| 7955. |
- Breasson, Ludovic, et al.
(författare)
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PI3K gamma ablation does not promote diabetes in db/db mice, but improves insulin sensitivity and reduces pancreatic beta-cell apoptosis
- 2018
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Ingår i: Faseb Journal. - 0892-6638. ; 32:1
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Tidskriftsartikel (refereegranskat)abstract
- PI3K gamma has emerged as a promising target for the treatment of obesity and insulin resistance; however, previous studies have indicated that PI3K gamma activity in pancreatic beta cells is required for normal insulin secretion in response to glucose. Hence, a possible deterioration of insulin secretion capacity in patients who are predisposed to the failure of pancreatic beta-cell function is a major concern for the pharmacologic inhibition of PI3K gamma. To address this issue, we investigated the effects of PI3K gamma ablation in db/db diabetic mice, a genetic model of obesity-driven beta-cell failure and diabetes. Mice that lacked PI3K gamma were backcrossed into db/+ mice C57BL/KS (>10 generations) to obtain db/db-PI3K gamma(-/-) mice. db/db-PI3K gamma(-/-) mice and control db/db mice were phenotyped for glucose homeostasis, insulin sensitivity, insulin secretion, steatosis, metabolic inflammation, pancreatic islet morphometry, islet cellular composition, and inflammation. Pancreatic beta-cell apoptosis and proliferation were also evaluated. db/db-PI3K gamma(-/-) mice and control db/db mice developed similar body weight, steatosis, glycemia, and insulin levels after a glucose load; however, db/db-PI3K gamma(-/-) mice displayed improved insulin tolerance, higher levels of fasting seruminsulin, and lower pancreatic insulin content. In db/db-PI3K gamma(-/-) mice, the number of adipose tissue macrophages was similar to control, but displayed reduced adipose tissue neutrophils and M2-polarized adipose tissue gene expression. Finally, db/db-PI3K gamma(-/-) mice have more pancreatic beta cells and larger islets than db/db mice, despite displaying similar islet inflammation. This phenotype could be explained by reduced beta-cell apoptosis in db/db-PI3K gamma(-/-) mice compared with control db/db mice. Our results are consistent with the concept that the beneficial action of PI3K gamma ablation in obesity-driven glucose intolerance is largely a result of its leptin-dependent effects on adiposity and, to a lesser extent, the promotion of adipose tissue neutrophil recruitment and M1 polarization of gene expression. Of importance, our data challenge the concept that PI3K gamma is required for insulin secretion in response to glucose in vivo, and indicate that PI3K gamma ablation protects db/db mice from beta-cell apoptosis and improves fasting insulin levels. We conclude that PI3K gamma inhibition in obese patients who are predisposed to beta-cell failure is not expected to produce adverse effects on insulin secretion.
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| 7956. |
- Bredenberg, Johan, et al.
(författare)
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Conformational states of the glucocorticoid receptor DNA-binding domain from molecular dynamics simulations
- 2002
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Ingår i: Proteins. - : Wiley. - 0887-3585 .- 1097-0134. ; 49:1, s. 24-36
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Tidskriftsartikel (refereegranskat)abstract
- Molecular dynamics simulations (MD) have been performed on variant crystal and NMR-derived structures of the glucocorticoid receptor DNA-binding domain (GR DBD). A loop region five residues long, the so-called D-box, exhibits significant flexibility, and transient perturbations of the tetrahedral geometry of two structurally important Cys4 zinc finger are seen, coupled to conformational changes in the D-box. In some cases, one of the Cys ligands to zinc exchanges with water, although no global distortion of the protein structure is observed. Thus, from MD simulation, dynamics of the D-box could partly be explained by solvent effects in conjunction with structural reformation of the zinc finger.
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| 7957. |
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| 7958. |
- Brehwens, Karl, 1983-
(författare)
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In vitro and in vivo aspects of intrinsic radiosensitivity
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis focuses on how physical and biological factors influence the outcome of exposures to γ/X-rays. That the dose rate changes during real life exposure scenarios is well-known, but radiobiological data from exposures performed at increasing or decreasing dose rates is lacking. In paper I, it was found that an exposure where the dose rate decreases exponentially induces significantly higher levels of micronuclei in TK6 cells than exposures at an increasing or constant dose rate. Paper II describes the construction and validation of novel exposure equipment used to further study this “decreasing dose rate effect”, which is described in paper III. In paper I we also observed a radioprotective effect when cells were exposed on ice. This “temperature effect” (TE) has been known for decades but it is still not fully understood how hypothermia acts in a radioprotective manner. This was investigated in paper IV, where a multiparametric approach was used to investigate the underlying mechanisms. In paper V the aim was to investigate the role of biomarkers and clinical parameters as possible risk factors for late adverse effects to radiotherapy (RT). This was studied in a rare cohort of head-and-neck cancer patients that developed mandibular osteoradionecrosis (ORN) as a severe late adverse effect of RT. Biomarker measurements and clinical factors were then subjected to multivariate analysis in order to identify ORN risk factors. The results suggest that the patient’s oxidative stress response is an important factor in ORN pathogenesis, and support the current view that patient-related factors constitute the largest source of variation seen in the frequency of late adverse effects to RT.In summary, this thesis provides new and important insights into the roles of biological and physical factors in determining the consequences of γ/X-ray exposures.
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| 7959. |
- Brehwens, Karl, 1983-, et al.
(författare)
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Micronucleus frequencies and clonogenic cell survival in TK6 cells exposed to changing dose rates under controlled temperature conditions
- 2014
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Ingår i: International Journal of Radiation Biology. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 90:3, s. 241-247
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: In most exposure scenarios the dose rate of exposure is not constant. Despite this, very little information exists on the possible biological effects of exposing cells to radiation under the conditions of a changing dose rate. The current study highlights interesting effects following exposure under these conditions.Materials and methods: We constructed a new exposure facility that allows exposing cells inside an incubator and used it to irradiate human lymphoblastoid TK6 cells both after a moderate (0.48 Gy) and a high (1.1 Gy) dose, where the change in dose rate was, respectively, ≈ 17-fold change (2.2 - 37 mGy/min) and ≈ 39-fold (2.7 - 106 mGy/min). Clonogenic survival and micronuclei (MN) induction were the chosen endpoints.Results: The obtained results confirm the outcome of our first study that TK6 cells exposed to a decreasing dose rate express more MN than cells exposed to an increasing or constant dose rate. The effect was not seen after the moderate dose of 0.48 Gy or detectable at the level of clonogenic cell survival.Conclusions: We speculate that the high level of MN is probably related to a delayed elimination of damaged cells by interphase death, as opposed to mechanisms relating to DNA damage and repair.
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| 7960. |
- Breidenstein, Annika, et al.
(författare)
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PrgE: an OB-fold protein from plasmid pCF10 with striking differences to prototypical bacterial SSBs
- 2024
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Ingår i: Life Science Alliance. - : Life Science Alliance. - 2575-1077. ; 7:8
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Tidskriftsartikel (refereegranskat)abstract
- A major pathway for horizontal gene transfer is the transmission of DNA from donor to recipient cells via plasmid-encoded type IV secretion systems (T4SSs). Many conjugative plasmids encode for a single-stranded DNA-binding protein (SSB) together with their T4SS. Some of these SSBs have been suggested to aid in establishing the plasmid in the recipient cell, but for many, their function remains unclear. Here, we characterize PrgE, a proposed SSB from the Enterococcus faecalis plasmid pCF10. We show that PrgE is not essential for conjugation. Structurally, it has the characteristic OB-fold of SSBs, but it has very unusual DNA-binding properties. Our DNA-bound structure shows that PrgE binds ssDNA like beads on a string supported by its N-terminal tail. In vitro studies highlight the plasticity of PrgE oligomerization and confirm the importance of the N-terminus. Unlike other SSBs, PrgE binds both double- and single-stranded DNA equally well. This shows that PrgE has a quaternary assembly and DNA-binding properties that are very different from the prototypical bacterial SSB, but also different from eukaryotic SSBs.
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