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St-Pierre J.,University of Alberta | Lysechko T.L.,University of Alberta | Lysechko T.L.,Afexa Life Sciences Inc. | Ostergaard H.L.,University of Alberta
Cellular Signalling | Year: 2011

Pyk2 is a non-receptor tyrosine kinase that regulates cellular adhesion. We generated antibodies to a peptide corresponding to the N-terminus (NT) of Pyk2 and another to a portion of the C-terminal (CT) domain. Only the CT antiserum recovered paxillin-associated Pyk2. These antibodies recognized overlapping but biochemically distinct molecular species of Pyk2 since the CT antiserum recovered Pyk2 after NT antibody immunodepletion. Furthermore, the CT antibody could not immunoblot NT antibody-captured Pyk2. Phosphorylation partially accounts for the differential binding of these antibodies as dephosphorylation of Pyk2 recovered with the NT antibodies allows for recognition by the CT antibody. Additionally, Pyk2 recovered with the NT antibody displays increased serine/threonine phosphorylation. We suggest that the NT epitope is inaccessible to the antibody because Pyk2 is in a closed confirmation in association with paxillin. Upon induction of serine and/or threonine phosphorylation of Pyk2, it opens to a confirmation that allows for antibody binding to the NT epitope but at the same time no longer binds paxillin or the CT antiserum. These antibodies also display differential staining of Pyk2 in both T cells and macrophages. Pyk2 recognized by the CT antibody, but not the NT antibody, colocalized with paxillin at the microtubule-organizing center (MTOC). The MTOC-bound Pyk2 was not tyrosine phosphorylated upon T cell activation. We hypothesize that a reservoir of primarily inactive Pyk2 associates with paxillin at the MTOC, which may allow for rapid delivery of Pyk2 to specific sites of adhesion. © 2010 Elsevier Inc.

Lysechko T.L.,University of Alberta | Lysechko T.L.,Afexa Life Sciences Inc. | Cheung S.M.S.,University of Alberta | Ostergaard H.L.,University of Alberta
Journal of Biological Chemistry | Year: 2010

Pyk2 was identified as a Ca2+-dependent kinase, however, the regulation of Pyk2 by Ca2+ in T cells remains controversial. We found that Ca2+ mobilization preferentially induced Pyk2 phosphorylation in cytotoxic T lymphocytes (CTL). Furthermore, Pyk2 phosphorylation in CTL was not absolutely Ca2+ dependent but relied on the strength of T cell receptor stimulation. Ionomycin-stimulated Pyk2 phosphorylation did not require calmodulin activity, because phosphorylation was not inhibited by the calmodulin inhibitor W7, and we detected no Ca2+-regulated association between Pyk2 and calmodulin. Ca2+-stimulated Pyk2 phosphorylation was dependent on Src-family kinase activity, even at the Pyk2 autophosphorylation site. We sought to identify a Ca2+-regulated pathway that could trigger Pyk2 phosphorylation in T cells and found that ionomycin stimulated the production of reactive oxygen species and an H2O2 scavenger inhibited ionomycin-induced Pyk2 phosphorylation. Additionally, H 2O2 induced strong Erk activation and ionomycin-stimulated Pyk2 phosphorylation was Erk dependent. These data support the conclusion that Ca2+ mobilization induces the production of reactive oxygen species, which in turn activate the Erk pathway, leading to Src-family kinase-dependent Pyk2 phosphorylation. Our data demonstrate that Pyk2 is not a Ca 2+-dependent kinase in T cells but instead, increased intracellular Ca2+ induces Pyk2 phosphorylation through production of reactive oxygen species. These findings are consistent with the possibility that Pyk2 acts as an early sensor of numerous extracellular signals that trigger a Ca 2+ flux and/or reactive oxygen species to amplify tyrosine phosphorylation signaling events. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.

Afexa Life Sciences Inc. | Date: 2013-03-18

The invention is directed to ginseng fractions and methods for activating innate and adaptive immune responses to prevent, treat or ameliorate a condition in a subject by administering to the subject an effective amount of a ginseng traction, a pharmaceutical composition comprising the fraction in combination with another medicament or with one or more pharmaceutically acceptable carriers, or a food item comprising the fraction. The fraction may be made from

Afexa Life Sciences Inc. | Date: 2010-08-20

all natural health food supplements, namely, health food supplements from herbal sources which are in the form of ground or dry product, in solution or as an extract of herbal sources.

Miller S.C.,McGill University | Delorme D.,McGill University | Shan J.J.,Afexa Life Sciences Inc.
Journal of Complementary and Integrative Medicine | Year: 2011

In a recent study involving normal, juvenile mice, we showed that CVT-E002, a proprietary extract (Afexa Life Sciences, Inc.) of North American ginseng, Panax quinquefolius, significantly enhanced the absolute levels of cells acting at the first line of defense in tumor combat, i.e., natural killer (NK) cells. The present study evaluated the effect of CVT-E002, on life span when administered intraperitoneally to leukemic, infant/juvenile mice. The extract was administered to groups of mice daily for 14 days in several dosing groups up to 50mg/day from age 7 to 21 days. The tumor was administered intraperitoneally under sterile conditions, in a laminar flow hood at 7 days of age (0.5 x 106 leukemic cells), immediately receding the first CVT-E002 injection for each dose group. The data revealed that CVT-E002 significantly extends the life of leukemic, young mice in a dose-specific manner, i.e., 20 mg/day was effective in extending life, while lower doses of 5, 10 mg as well as higher doses of 30, 40, 50 mg per day were completely ineffective. We have already shown that CVT-E002 significantly elevates NK cells in normal and leukemic, adult mice, as well as in normal, infant/juvenile mice, and we have also shown that CVT-E002 significantly extends the life span of leukemic, adult mice. The results of the present study did indeed show that (i) CVT-E002 extends the life span of leukemic, infant/juvenile mice, and (ii) that the dose of CVT-E002 is critical in achieving life span augmentation in these leukemic infant/juvenile mice. © 2011 Berkeley Electronic Press. All rights reserved.

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