Ad no adverse side effects, unlike chemotherapy, and improved the outcome of treatment; at high plasma level, DHA has a potential to specifically chemosensitize Scutellarein web tumors for better therapeutic effects. Some studies suggested that COX inhibitors, primarily blocking AA metabolism, are effective in the prevention of prostate and colon cancer. However, the severe cardiovascular side effects of COX-2 inhibitors has threatened the clinical application of these inhibitors. To examine the beneficial effects of modulating dietary fat content and the n-6/n-3 PUFA ratio in prostate cancer patients on the Insulin-like growth factor/Insulin-like growth factor-binding protein system and the COX-2/PGE-2 pathways, Aronson et al. initiated a phase II prospective randomized trial focused on low-fat diet supplemented with fish oil in patients undergoing radical prostatectomy. In the low-fat fish oil vs. western diet group, n-6/n-3 ratios were reduced in benign and malignant prostate tissue, cell proliferation was reduced as determined by a reduced proliferation index both in vivo and in vitro, and there was no significant difference in mean PGE2 levels, COX-2, apoptosis, or angiogenesis PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19850363 immunostaining.However, for several other proteins the functional status has been overturned, and proteins including CASK, haspin, WNK1, HER3, and STRAD have been shown to have 169939-93-9 biological activity ATP-binding and catalytic activity that can be achieved through non-canonical mechanisms3034. Each of these pseudokinases utilizes a distinct mechanism to carry out its cellular functions. For example, WNK1 compensates for the missing ATP-binding lysine in -strand 3 by employing instead a lysine residue in the nucleotide binding loop32. The calcium calmodulin-activated serine-threonine kinase CASK displays atypical catalytic activity in that Mg2+ inhibits its activity30. HER3 lacks the catalytic base aspartate and the crystal structure reveal that it assumes an atypical conformation for active kinases, particularly in C helix and activation segment33, 35. However, HER3 was found to retain low levels kinase activity and phosphorylate its intracellular region in vitro, but the physiological role of this activity remains to be determined33. These results argue that each alleged pseudokinase needs to be functionally analyzed and scrutinized for possible catalytic activity. In this study, we have shown that, both in vitro and in cells, the pseudokinase domain of JAK2 is an active dual-specificity protein kinase that phosphorylates two previously identified negative regulatory sites in JAK2, Ser523 and Tyr570. Phosphorylation of these sites is required to maintain low basal activity of JAK2. Our results on the catalytic activity of JH2 provide novel insights into the regulation of JAK activation in signaling by a variety of cytokines such as Epo, Tpo, IFN-, growth hormone, prolactin, IL-3, IL-5, and GM-CSF. In unstimulated cells, Ser523 has been shown to be the only constitutively phosphorylated residue in JAK25, and phosphorylation of other sites, including Tyr570, occurs only upon cytokine stimulation and activation of JAK29, 10. The kinases responsible for phosphorylation of Ser523 and Tyr570 have not been identified, but the activity of JH1 was 
not required for these phosphorylation events.5,7,9,10 We show here that JH2 phosphorylates Ser523 and Tyr570, and that autophosphorylation of Ser523 is the primary event in JH2 activation and it is observed in unstimulated conditions. Cytokine-induced receptor d.Ad no adverse side effects, unlike chemotherapy, and improved the outcome of treatment; at high plasma level, DHA has a potential to specifically chemosensitize tumors for better therapeutic effects. Some studies suggested that COX inhibitors, primarily blocking AA metabolism, are effective in the prevention of prostate and colon cancer. However, the severe cardiovascular side effects of COX-2 inhibitors has threatened the clinical application of these inhibitors. To examine the beneficial effects of modulating dietary fat content and the n-6/n-3 PUFA ratio in prostate cancer patients on the Insulin-like growth factor/Insulin-like growth factor-binding protein system and the COX-2/PGE-2 pathways, Aronson et al. initiated a phase II prospective randomized trial focused on low-fat diet supplemented with fish oil in patients undergoing radical prostatectomy. In the low-fat fish oil vs. western diet group, n-6/n-3 ratios were reduced in benign and malignant prostate tissue, cell proliferation was reduced as determined by a reduced proliferation index both in vivo and in vitro, and there was no significant difference in mean PGE2 levels, COX-2, apoptosis, or angiogenesis PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19850363 immunostaining.However, for several other proteins the functional status has been overturned, and proteins including CASK, haspin, WNK1, HER3, and STRAD have been shown to have ATP-binding and catalytic activity that can be achieved through non-canonical mechanisms3034. Each of these pseudokinases utilizes a distinct mechanism to carry out its cellular functions. For example, WNK1 compensates for the missing ATP-binding lysine in -strand 3 by employing instead a lysine residue in the nucleotide binding loop32. The calcium calmodulin-activated serine-threonine kinase CASK displays atypical catalytic activity in that Mg2+ inhibits its activity30. HER3 lacks the catalytic base aspartate and the crystal structure reveal that it assumes 
an atypical conformation for active kinases, particularly in C helix and activation segment33, 35. However, HER3 was found to retain low levels kinase activity and phosphorylate its intracellular region in vitro, but the physiological role of this activity remains to be determined33. These results argue that each alleged pseudokinase needs to be functionally analyzed and scrutinized for possible catalytic activity. In this study, we have shown that, both in vitro and in cells, the pseudokinase domain of JAK2 is an active dual-specificity protein kinase that phosphorylates two previously identified negative regulatory sites in JAK2, Ser523 and Tyr570. Phosphorylation of these sites is required to maintain low basal activity of JAK2. Our results on the catalytic activity of JH2 provide novel insights into the regulation of JAK activation in signaling by a variety of cytokines such as Epo, Tpo, IFN-, growth hormone, prolactin, IL-3, IL-5, and GM-CSF. In unstimulated cells, Ser523 has been shown to be the only constitutively phosphorylated residue in JAK25, and phosphorylation of other sites, including Tyr570, occurs only upon cytokine stimulation and activation of JAK29, 10. The kinases responsible for phosphorylation of Ser523 and Tyr570 have not been identified, but the activity of JH1 was not required for these phosphorylation events.5,7,9,10 We show here that JH2 phosphorylates Ser523 and Tyr570, and that autophosphorylation of Ser523 is the primary event in JH2 activation and it is observed in unstimulated conditions. Cytokine-induced receptor d.
