• BMB Reports
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• v.42 no.1
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• pp.35-40
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• 2009

Protein kinase D2 (PKD2) is a member of the PKD serine/threonine protein kinase family that has been implicated in the regulation of a variety of cellular processes including proliferation, survival, protein trafficking and immune response. In the present study, we report a novel interaction between PKD2 and Lck, a member of the Src tyrosine protein kinase family that is predominantly expressed in T cells. This interaction involved the C-terminal kinase domains of both PKD2 and Lck. Moreover, co-expression of Lck enhanced the tyrosine phosphorylation of PKD2 and increased its kinase activity. Finally, we report that PKD2 enhanced T cell receptor (TCR)-induced nuclear factor of T cell (NFAT) activity in Jurkat T cells. These results suggested that Lck regulated the activity of PKD2 by tyrosine phosphorylation, which in turn may have modulated the physiological functions of PKD2 during TCR-induced T cell activation.

• Clinical and Experimental Reproductive Medicine
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• v.47 no.3
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• pp.180-185
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• 2020

Objective: Tyrosine phosphorylation is an essential process in many biological systems, including the male reproductive system. The presence of tyrosine-phosphorylated (TyrPho) proteins has been well documented in male reproductive organs, but research in fertile females is still limited. Methods: The ovary, oviduct, and uterus of adult female Sprague-Dawley rats in the estrus phase were used to localize TyrPho proteins using an immunohistochemical technique. These proteins were separated and their expression patterns were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis, respectively. Results: TyrPho proteins were localized in the cytoplasm of the oocyte except the antral fluid; in the granulosa cells, theca cells, and stromal cells of the ovary; at the apical surface of oviductal epithelial cells; and in the basal epithelium and submucosa of the uterine wall. Moreover, we found that 72-, 43-, and 28-kDa TyrPho proteins were localized in the ovary, while 170-, 55-, and 43-kDa proteins were localized in the oviduct. In the uterus, we detected four major bands, corresponding to 61-, 55-, 54-, and 43-kDa TyrPho proteins. Conclusion: Given that these TyrPho proteins were found in major reproductive organs in the estrus phase, these proteins may play important roles in female fertility.

• Molecules and Cells
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• v.44 no.7
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• pp.493-499
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• 2021

Parkinson's disease (PD) is characterized by a progressive loss of dopamine-producing neurons in the midbrain, which results in decreased dopamine levels accompanied by movement symptoms. Oral administration of l-3,4-dihydroxyphenylalanine (L-dopa), the precursor of dopamine, provides initial symptomatic relief, but abnormal involuntary movements develop later. A deeper understanding of the regulatory mechanisms underlying dopamine homeostasis is thus critically needed for the development of a successful treatment. Here, we show that p21-activated kinase 4 (PAK4) controls dopamine levels. Constitutively active PAK4 (caPAK4) stimulated transcription of tyrosine hydroxylase (TH) via the cAMP response element-binding protein (CREB) transcription factor. Moreover, caPAK4 increased the catalytic activity of TH through its phosphorylation of S⁴⁰, which is essential for TH activation. Consistent with this result, in human midbrain tissues, we observed a strong correlation between phosphorylated PAK4^S474, which represents PAK4 activity, and phosphorylated TH^S40, which reflects their enzymatic activity. Our findings suggest that targeting the PAK4 signaling pathways to restore dopamine levels may provide a new therapeutic approach in PD.

• IMMUNE NETWORK
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• v.1 no.3
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• pp.196-202
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• 2001

Backgorund: WEHI-231 B cell line is a representative model for $IgM^+$ mature B cells. To understand the signaling differences between mature and immature B cells, we compared the responsiveness of WEHI-231 and Bal 17 B cell lines to BCR cross-linking. Methods: The extents of tyrosine phosphorylation, ligand-induced internalization, and activation-induced cell death upon BCR cross-linking were compared in two cell lines. Results: Despite a higher expression of BCR, cross-linking of BCR on WEHI-231 cell evoked a weaker level of tyrosine phosphorylation and BCR endocytosis than Bal 17 cells. Furthermore, the endocytosed BCR could not enter the lysosomal compartment and stayed as peripheral spots in WEHI-231 cells. Conclusion: WEHI-231 cell showed preferred BCR-mediated signaling pathways leading to a reduced capability of antigen presentation as well as the enhanced apoptosis in comparision with Bal 17 cells. These results might reflect the signaling differences between mature and immature B cells.

• YAKHAK HOEJI
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• v.41 no.5
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• pp.588-594
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• 1997

N-(tert-Butoxycarbonyl)-O-(dicyanoethylthiophosphono)-L-tyrosine(7), the key intermediate for the synthesis of thiophosphotyrosine-containing peptide derivat ives, was prepared. For the phosphorylation, we used t-Boc-tyrosine and phosphoramidite in the presence of 1H-tetrazol. For the protection of thiophosphate moiety, cyanoethyl protecting group was used. Thiophosphotyrosine-containing peptides could be used as tools for the elucidation of mechanism of signal transduction pathway and also prepared as PTK inhibitors, PTPase inhibitors and cytosolic protein binding blockers. It may be contributed for the development of potential anticancer agents.

• Journal of Physiology & Pathology in Korean Medicine
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• v.20 no.2
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• pp.477-481
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• 2006

A clinical report indicates that 'Geijibokryunghwan(GBH) is very effective in treating thrombosis in those patients who have difficulties with more conventional antithrombotic drugs. The isolation and identification of various compounds from this plant and the same genus have been reported by several groups. However, the pharmaceutical effect of the GBH on superoxide generation in human neutrophils has not been studied. In the present report, we investigated the possibility of using herbal medicine as an alternative therapy. In particular, we studied tremor in antiatheroscleosis. In this report, we shows the GBH extract can be used as a potential atherosclerosis preventive agent in human. The effect of GBH on stimulus-induced superoxide generation and phosphorylation of tyrosine residues of protein in human neutrophils was investigated. In a conclusion, GBH suppressed tyrosine phosphorylase in a dose-dependent manner, and may have pharmacoceutical applications. These data suggest that GBH extracts merits investigation as a potential anti-atherosclerogenic agent in humans.

• The Korean Journal of Physiology
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• v.30 no.2
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• pp.209-218
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• 1996

Acetylcholine (ACh) activates the inwardly rectifying muscarinic $K^{+}$ channel in rat atrial cells via pertussis toxin (PTX)-sensitive G-protein ($G_k$) coupled with the muscarinic receptor (mAChR). Although this $K^{+}\;(K_{ACh})$ channel function has reported to be modulated by the phosphorylation process, a kinase and phosphatase involved in these processes are still unclear. Since either PKA or PKC was not effective on this ATP-modulation, the present study examined the possible involvement of the protein tyrosine kinase (PTK) and protein tyrosine phosphatase (PTP) in the function of the $K_{ACh}$ Channel. In the inside-out (I/O) patch preparation excised from the adult rat atrial cell, when activated by 10 ${\mu}M$ ACh in the pipette and 100 ${\mu}M$ GTP in the bath, the mean open time (${\tau}_{o}$) and the channel activity ($K_{ACh}$) was 1.13 ms (n=5) and 0.19 (n=6), respectively. Following the application of 1 mM ATP into the bath, ${\tau}_{o}$ increased by 34% (1.54 ms, n=5) and $K_{ACh}$ by 66% (0.28, n=6). Channel function elevated by ATP was lasted after washout of ATP. However, this ATP-induced increase in the $K_{ACh}$ channel function did not occur in pretreated cells with genistein ($50{\sim}100 {\mu}M$), a selective PTK inhibitor, but occurred in pretreated cells with equimolar daidzein, a negative control of the genistein. On the contrary, PTP which acts on tyrosine residue conversely reversed both ATP-induced increased ${\tau}_{o}$ by 32% (1.20 ms, n=3) and $K_{ACh}$ by 41% (0.15, n=3), respectively. Taken together, these results suggest that $K_{ACh}$ channel may, at least partly, be regulated by the tyrosyl phosphorylation, although it is unclear where this process exerts on the muscarinic signal transduction pathway comprising the mAChR-$G_{k}$-the $K_{ACh}$ channel.

• Journal of Applied Biological Chemistry
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• v.48 no.3
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• pp.120-126
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• 2005

Endothelial nitric oxide synthase (eNOS) plays a critical role in vascular biology and pathophysiology. Its activity is regulated by multiple mechanisms such as calcium/calmodulin, protein-protein interactions, sub-cellular locations and phosphorylation at various sites. Phosphorylation of eNOS-Ser1177 (based on mouse sequence) has been identified as an important mechanism of eNOS activation. However, signaling pathway leading to it phosphorylation remains controversial. The regulation of eNOS-Ser1177 phosphorylation by Src and protein kinase A (PKA) was investigated in the present study using cultured mouse aorta endothelial cells. Expression of a constitutively active Src mutant in the cells enhanced phosphorylation of eNOS and protein kinase B (Akt). The Src-stimulated phosphorylation was not attenuated by the expression of a dominant negative PKA regulatory subunit. Neither activation nor inhibition of PKA activity had any significant effect on tyrosine phosphorylation of activation or inactivation site in Src. Based on the results of this study, it is suggested that Src/Akt pathway and PKA signaling may regulate eNOS phosphorylation independently. The existence of multiple mechanisms for eNOS phosphorylation may guarantee endothelial nitric oxide production in various cellular contexts which is essential for maintenance of vascular health.

• Proceedings of the Zoological Society Korea Conference
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• 1999.04a
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• pp.65.1-65
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• 1999

No Abstract, See Full Text

• Proceedings of the Zoological Society Korea Conference
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• 1997.04a
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• pp.79.1-79
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• 1997

No Abstract, See Full Text