The Class I HLA Repertoire of Pancreatic Islets Comprises the Nonclassical Class Ib Antigen HLA-G

We examined whether 1,25 dihydroxyvitamin D(3) (1,25 D(3)), the active form of vitamin D involved in the regulation of the immune system, may also protect human pancreatic islet cells from destruction induced by cytokines. In this study, we specifically investigated the effect of 1,25 D(3) on oxidative stress and major histocompatibility complex (MHC) induction, both implicated in cytokine-induced islet cell dysfunction and destruction. We also investigated the effects of 1,25 D(3) on interleukin (IL)-6, a pleiotropic cytokine implicated in the pathogenesis of immunoinflammatory disorders. Human pancreatic islets, isolated from heart-beating donors, were treated with a combination of three cytokines, IL-1beta+tumor necrosis factor alpha+interferon gamma, in the presence or absence of vitamin D, and compared with with untreated control cells. Metabolic activity was assessed by cell viability and insulin content. Oxidative stress was estimated by heat shock protein 70 (hsp70) expression, cell manganese superoxide dismutase (MnSOD) activity and nitrite release, a reflexion of nitric oxide (NO) synthesis. Variation of immunogenicity of islet preparations was determined by analysis of the MHC class I and class II transcripts. Inflammatory status was evaluated by IL-6 production. After 48 h of contact with cytokines, insulin content was significantly decreased by 40% but cell viability was not altered. MHC expression significantly increased six- to sevenfold as well as NO and IL-6 release (two- to threefold enhancement). MnSOD activity was not significantly induced and hsp70 expression was not affected by the combination of cytokines. The addition of 1,25 D(3) significantly reduced nitrite release, IL-6 production and MHC class I expression which then became not significantly different from controls. These results suggest that the effect of 1,25 D(3) in human pancreatic islets cells may be a reduction of the vulnerability of cells to cytotoxic T lymphocytes and a reduction of cytotoxic challenge. Hence, 1,25 D(3) might play a role in the prevention of type 1 diabetes and islet allograft rejection.

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A convenient method of preparation of high-activity urease from Canavalia ensiformis by covalent chromatography and an investigation of its thiol groups with 2,2'-dipyridyl disulphide as a thiol titrant and reactivity probe

Biochemical Journal ◽

10.1042/bj1590245 ◽

1976 ◽

Vol 159 (2) ◽

pp. 245-257 ◽

Cited By ~ 61

Author(s):

R Norris ◽

K Brocklehurst

Keyword(s):

Convenient Method ◽

Specific Activity ◽

Class Ii ◽

High Reactivity ◽

Class I ◽

Thiol Groups ◽

Class Iii ◽

Active Centre ◽

Class Ib ◽

Covalent Chromatography

1. A convenient method of preparation of jack-bean urease (EC3.5.1.5) involving covalent chromatography by thiol-disulphide interchange is described. 2. Urease thus prepared has specific activity comparable with the highest value yet reported (44.5 ± 1.47 kat/kg, Km = 3.32 ± 0.05 mM; kcat. = 2.15 × 104 ± 0.05 × 104s-1 at pH7.0 and 38°C). 3. Titration of the urease thiol groups with 2,2'-dipyridyl disulphide (2-Py-S-S-2-Py) and application of the method of Tsou Chen-Lu [(1962) Sci. Sin.11, 1535-1558] suggests that the urease molecule (assumed to have mol.wt. 483000 and ε280 = 2.84 × 105 litre·mol-1-cm-1) contains 24 inessential thiol groups of relatively high reactivity (class-I), six ‘essential’ thiol groups of low reactivity (class-II) and 54 buried thiol groups (class-III) which are exposed in 6M-guanidinium chloride. 4. The reaction of the class-I thiol groups with 2-Py-S-S-2-Py was studied in the pH range 6-11 at 25°C(I = 0.1 mol/l) by stopped-flow spectrophotometry, and the analogous reaction of the class-II thiol groups by conventional spectrophotometry. 5. The class-I thiol groups consist of at least two sub-classes whose reactions with 2-Py-S-S-2-Py are characterized by (a) pKa = 9.1, k = 1.56 × 104M-1·s-1 and (b) pKa = 8.1, k = 8.05 × 102M-1·s-1 respectively. The reaction of the class-II thiol groups is characterized by pKa = 9.15 and k = 1.60 × 102M-1·s-1. 6. At pH values 7-8 the class-I thiol groups consist of approx. 50% class-Ia groups and 50% class-Ib groups. The ratio class Ia/class Ib decreases as the pH is raised according to a pKa value ≥ approx. 9.5, and at high pH the class-I thiol groups consist of at most 25% class-Ia groups and at least 75% class-Ib groups. 7. The reactivity of the class-II thiol groups towards 2-Py-S-S-2-Py is insensitive to the nature of the group used to block the class-I thiols. 8. All the ‘essential’ thiol groups in urease appear to be eeactive only as uncomplicated thiolate ions. The implications of this for the active-centre chemistry of urease relative to that of the thiol proteinases are discussed.

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The Nonclassical Class I Molecule CD1d Associates with the Novel CD8 Ligand gp180 on Intestinal Epithelial Cells

Journal of Biological Chemistry ◽

10.1074/jbc.274.37.26259 ◽

1999 ◽

Vol 274 (37) ◽

pp. 26259-26265 ◽

Cited By ~ 41

Author(s):

Nicola A. Campbell ◽

Hyun S. Kim ◽

Richard S. Blumberg ◽

Lloyd Mayer

Keyword(s):

Epithelial Cells ◽

Intestinal Epithelial Cells ◽

Class I ◽

Intestinal Epithelial ◽

The Novel ◽

Nonclassical Class

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Conserved lipid and peptide presentation functions of nonclassical class I molecules

Immunology Today ◽

10.1016/s0167-5699(99)01521-2 ◽

1999 ◽

Vol 20 (11) ◽

pp. 515-521 ◽

Cited By ~ 19

Author(s):

Mitchell Kronenberg ◽

Laurent Brossay ◽

Zoran Kurepa ◽

James Forman

Keyword(s):

Class I ◽

Peptide Presentation ◽

Nonclassical Class

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The Murine Nonclassical Class I Major Histocompatibility Complex–like CD1.1 Molecule Protects Target Cells from Lymphokine-activated Killer Cell Cytolysis

Journal of Experimental Medicine ◽

10.1084/jem.189.3.483 ◽

1999 ◽

Vol 189 (3) ◽

pp. 483-491 ◽

Cited By ~ 29

Author(s):

Chew Shun Chang ◽

Laurent Brossay ◽

Mitchell Kronenberg ◽

Kevin P. Kane

Keyword(s):

Major Histocompatibility Complex ◽

Nk Cell ◽

Killer Cell ◽

Class I ◽

Target Cells ◽

Inhibitory Receptor ◽

Major Histocompatibility ◽

Lymphokine Activated Killer Cell ◽

Histocompatibility Complex ◽

Nonclassical Class

Classical class I major histocompatibility complex (MHC) molecules, as well as the nonclassical class I histocompatibility leukocyte antigen (HLA)-E molecule, can negatively regulate natural killer (NK) cell cytotoxicity through engagement of NK inhibitory receptors. We show that expression of murine (m)CD1.1, a nonpolymorphic nonclassical MHC class I–like molecule encoded outside the MHC, protects NK-sensitive RMA/S target cells from adherent lymphokine-activated killer cell (A-LAK) cytotoxicity. Passage of effector cells in recombinant interleukin (rIL)-2 enhanced protection by mCD1.1, suggesting an expansion of relevant A-LAK population(s) or modulation of A-LAK receptor expression. Murine CD1.1 conferred protection from lysis by rIL-2–activated spleen cells of recombination activating gene (Rag)-1−/− mice, which lack B and T cells, demonstrating that mCD1.1 can protect RMA/S cells from lysis by NK cells. An antibody specific for mCD1.1 partially restored A-LAK lysis of RMA/S.CD1.1 transfectants, indicating that cell surface mCD1.1 can confer protection from lysis; therefore, mCD1.1 possibly acts through interaction with an NK inhibitory receptor. CD1.1 is by far the most divergent class I molecule capable of regulating NK cell activity. Finally, mCD1.1 expression rendered RMA/S cells resistant to lysis by A-LAK of multiple mouse strains. The conserved structure of mCD1.1 and pattern of mCD1.1 resistance from A-LAK lysis suggest that mCD1.1 may be a ligand for a conserved NK inhibitory receptor.

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In vivo role of ER-associated peptidase activity in tailoring peptides for presentation by MHC class Ia and class Ib molecules

Journal of Experimental Medicine ◽

10.1084/jem.20052271 ◽

2006 ◽

Vol 203 (3) ◽

pp. 647-659 ◽

Cited By ~ 122

Author(s):

Jingbo Yan ◽

Vrajesh V. Parekh ◽

Yanice Mendez-Fernandez ◽

Danyvid Olivares-Villagómez ◽

Srdjan Dragovic ◽

...

Keyword(s):

Cytotoxic T Cells ◽

Surface Expression ◽

Proteolytic Processing ◽

Class I ◽

Cell Surface Expression ◽

Peptidase Activity ◽

Mhc Class Ia ◽

Class Ib

Endoplasmic reticulum (ER)-associated aminopeptidase (ERAP)1 has been implicated in the final proteolytic processing of peptides presented by major histocompatibility complex (MHC) class I molecules. To evaluate the in vivo role of ERAP1, we have generated ERAP1-deficient mice. Cell surface expression of the class Ia molecules H-2Kb and H-2Db and of the class Ib molecule Qa-2 was significantly reduced in these animals. Although cells from mutant animals exhibited reduced capacity to present several self- and foreign antigens to Kb-, Db-, or Qa-1b–restricted CD8+ cytotoxic T cells, presentation of some antigens was unaffected or significantly enhanced. Consistent with these findings, mice generated defective CD8+ T cell responses against class I–presented antigens. These findings reveal an important in vivo role of ER-associated peptidase activity in tailoring peptides for presentation by MHC class Ia and class Ib molecules.

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Function and Regulation of Class I Ribonucleotide Reductase-Encoding Genes in Mycobacteria

Journal of Bacteriology ◽

10.1128/jb.01409-08 ◽

2008 ◽

Vol 191 (3) ◽

pp. 985-995 ◽

Cited By ~ 35

Author(s):

Mohube B. Mowa ◽

Digby F. Warner ◽

Gilla Kaplan ◽

Bavesh D. Kana ◽

Valerie Mizrahi

Keyword(s):

Mycobacterium Smegmatis ◽

Chromosomal Region ◽

Class I ◽

Growth And Survival ◽

Ribonucleotide Reductases ◽

Genes Encoding ◽

R2 Subunit ◽

Encoding Genes ◽

Class Ib

ABSTRACT Ribonucleotide reductases (RNRs) are crucial to all living cells, since they provide deoxyribonucleotides (dNTPs) for DNA synthesis and repair. In Mycobacterium tuberculosis, a class Ib RNR comprising nrdE- and nrdF2-encoded subunits is essential for growth in vitro. Interestingly, the genome of this obligate human pathogen also contains the nrdF1 (Rv1981c) and nrdB (Rv0233) genes, encoding an alternate class Ib RNR small (R2) subunit and a putative class Ic RNR R2 subunit, respectively. However, the role(s) of these subunits in dNTP provision during M. tuberculosis pathogenesis is unknown. In this study, we demonstrate that nrdF1 and nrdB are dispensable for the growth and survival of M. tuberculosis after exposure to various stresses in vitro and, further, that neither gene is required for growth and survival in mice. These observations argue against a specialist role for the alternate R2 subunits under the conditions tested. Through the construction of nrdR-deficient mutants of M. tuberculosis and Mycobacterium smegmatis, we establish that the genes encoding the essential class Ib RNR subunits are specifically regulated by an NrdR-type repressor. Moreover, a strain of M. smegmatis mc2155 lacking the 56-kb chromosomal region, which includes duplicates of nrdHIE and nrdF2, and a mutant retaining only one copy of nrdF2 are shown to be hypersensitive to the class I RNR inhibitor hydroxyurea as a result of depleted levels of the target. Together, our observations identify a potential vulnerability in dNTP provision in mycobacteria and thereby offer a compelling rationale for pursuing the class Ib RNR as a target for drug discovery.

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Clustering ferry ports class-I based on the ferry ro-ro tonnages and main dimensions

MATEC Web of Conferences ◽

10.1051/matecconf/201818112001 ◽

2018 ◽

Vol 181 ◽

pp. 12001

Author(s):

Syamsul Asri ◽

Wahyuddin Mustafa ◽

Mohammad Rizal Firmansyah ◽

Farianto Fachruddin Lage

Keyword(s):

Capacity Constraint ◽

Class I ◽

Main Dimension ◽

Class Ib

Capacity constraint of port for Ferry Port Class I is not clearly stated in the Indonesian National Order of Port Affairs. It only said that ferry ship to be serviced is ships with more than 1000 gross tonnages (GTs). The word more than 1000 GTs is unclear as there are ships with up to 12500 GTs to be serviced in this port. This research introduces cluster of Ferry Port Class I. Ship main dimension and tonnage of sample ships is being used as a basis for the port clustering. The result shows that Ferry Port Class I should be divided into three main Ferry Port Classes I (Class IA, Class IB and Class IC). This new cluster of Ferry Port Class I can be used as a reference in updating the rules regarding ferry port class and as a reference in the design of ferry port main facilities.

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