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Sik Min - One of the best experts on this subject based on the ideXlab platform.

  • Deletion of Phospholipase D1 decreases bone mass and increases fat mass via modulation of Runx2, β-catenin-osteoprotegerin, PPAR-γ and C/EBPα signaling axis.
    Biochimica et biophysica acta. Molecular basis of disease, 2021
    Co-Authors: Dong Woo Kang, Younghoon Jang, Won Chan Hwang, Yu Na Noh, Kang Yell Choi, Xiangguo Che, Soung Hoon Lee, Je-yong Choi, Sik Min
    Abstract:

    Abstract In osteoporosis, mesenchymal stem cells (MSCs) prefer to differentiate into adipocytes at the expense of osteoblasts. Although the balance between adipogenesis and osteogenesis has been closely examined, the mechanism of commitment determination switch is unknown. Here we demonstrate that Phospholipase D1 (PLD1) plays a key switch in determining the balance between bone and fat mass. Ablation of PlD1 reduced bone mass but increased fat in mice. Mechanistically, PlD1/− MSCs inhibited osteoblast differentiaion with diminished Runx2 expression, while osteoclast differentiation was accelerated in PlD1−/− bone marrow-derived macrophages. PlD1−/− osteoblasts showed decreased expression of osteogenic makers. Increased number and resorption activity of osteoclasts in PlD1−/− mice were corroborated with upregulation of osteoclastogenic markers. Moreover, PlD1−/− osteoblasts reduced β-catenin mediated-osteoprotegerin (OPG) with increased RANKL/OPG ratio which resulted in accelerated osteoclast differentiation. Thus, low bone mass with upregulated osteoclasts could be due to the contribution of both osteoblasts and osteoclasts during bone remodeling. Moreover, ablation of PlD1 further increased bone loss in ovariectomized mice, suggesting that PLD1 is a negative regulator of osteoclastogenesis. Furthermore, loss of PLD1 increased adipogenesis, body fat mass, and hepatic steatosis along with upregulation of PPAR-γ and C/EBPα. Interestingly, adipocyte-specific PlD1 transgenic mice rescued the compromised phenotypes of fat mass and adipogenesis in PlD1 knockout mice. Collectively, PLD1 regulated the bifurcating pathways of mesenchymal cell lineage into increased osteogenesis and decreased adipogenesis, which uncovered a previously unrecognized role of PLD1 in homeostasis between bone and fat mass.

  • Phospholipase D1 inhibition sensitizes glioblastoma to temozolomide and suppresses its tumorigenicity.
    The Journal of pathology, 2020
    Co-Authors: Dong Woo Kang, Won Chan Hwang, Yu Na Noh, Kang Seo Park, Sik Min
    Abstract:

    Resistance of glioblastoma to the chemotherapeutic compound temozolomide is associated with the presence of glioblastoma stem cells in glioblastoma and is a key obstacle for the poor prognosis of glioblastoma. Here, we show that Phospholipase D1 is elevated in CD44High glioblastoma stem cells and in glioblastoma, especially recurring glioblastoma. Phospholipase D1 elevation positively correlated with the level of CD44 and poor prognosis in glioblastoma patients. Temozolomide significantly upregulated the expression of Phospholipase D1 in the low and moderate CD44 populations of glioblastoma stem cells, but not in the CD44High population in which Phospholipase D1 is highly expressed. Phospholipase D1 conferred resistance to temozolomide in CD44High glioblastoma stem cells and increased their self-renewal capacity and maintenance. Phospholipase D1 expression significantly correlated with levels of temozolomide resistance factors, which were suppressed by microRNA-320a and -4496 induced by Phospholipase D1 inhibition. Genetic and pharmacological targeting of Phospholipase D1 attenuated glioblastoma stem cell-derived intracranial tumors of glioblastoma using the microRNAs, and improved survival. Treatment solely with temozolomide produced no benefits on the glioblastoma, whereas in combination, Phospholipase D1 inhibition sensitized glioblastoma stem cells to temozolomide and reduced glioblastoma tumorigenesis. Together, these findings indicate that Phospholipase D1 inhibition might overcome resistance to temozolomide and represents a potential treatment strategy for glioblastoma. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

  • Phospholipase D1 is upregulated by vorinostat and confers resistance to vorinostat in glioblastoma
    Journal of cellular physiology, 2020
    Co-Authors: Dong Woo Kang, Younghoon Jang, Won Chan Hwang, Yu Na Noh, Youra Kang, Jung-ae Kim, Sik Min
    Abstract:

    Glioblastoma (GBM) is an aggressive brain tumor and drug resistance remains a major barrier for therapeutics. Epigenetic alterations are implicated in GBM pathogenesis, and epigenetic modulators including histone deacetylase (HDAC) inhibitors are exploited as promising anticancer therapies. Here, we demonstrate that Phospholipase D1 (PLD1) is a transcriptional target of HDAC inhibitors and confers resistance to HDAC inhibitor in GBM. Treatment of vorinostat upregulates PLD1 through PKCζ-Sp1 axis. Vorinostat induces dynamic changes in the chromatin structure and transcriptional machinery associated with PLD1 promoter region. Cotreatment of vorinostat with PLD1 inhibitor further attenuates invasion, angiogenesis, colony-forming capacity, and self-renewal capacity, compared with those of either treatment. PLD1 inhibitor overcomes resistance to vorinostat in GBM cells intracranial GBM tumors. Our finding provides new insight into the role of PLD1 as a target of resistance to vorinostat, and PLD1 inhibitor might provide the basis for therapeutic combinations with improved efficacy of HDAC inhibitor.

  • Targeting of Phospholipase D1 Ameliorates Collagen-Induced Arthritis via Modulation of Treg and Th17 Cell Imbalance and Suppression of Osteoclastogenesis
    International journal of molecular sciences, 2020
    Co-Authors: Hyun Jung Yoo, Won Chan Hwang, Sik Min
    Abstract:

    Phospholipase D1 (PLD1) plays a crucial role in various inflammatory and autoimmune diseases. Rheumatoid arthritis (RA) is a chronic and systemic autoimmune disease. However, the role of PLD1 in the pathogenesis of RA remains unknown. Here, we first investigated the role and effects of PLD1 in collagen-induced arthritis (CIA) and found that genetic and pharmacological inhibition of PLD1 in DBA1/J mice with CIA reduced the incidence of CIA, decreased the clinical score, and abrogated disease symptoms including infiltration of leukocytes, synovial inflammation, bone erosion, and cartilage destruction. Moreover, ablation and inhibition of PLD1 suppressed the production of type II collagen-specific IgG2a autoantibody and proinflammatory cytokines, accompanied by an increase in the regulatory T (Treg) cell population and a decrease in the Th17 cell population in CIA mice. The PLD1 inhibitor also promoted differentiation of Treg cells and suppressed differentiation of Th17 cells in vitro. Furthermore, the PLD1 inhibitor attenuated pathologic bone destruction in CIA mice by suppressing osteoclastogenesis and bone resorption. Thus, our findings indicate that the targeting of PLD1 can ameliorate CIA by modulating the imbalance of Treg and Th17 cells and suppressing osteoclastogenesis, which might be a novel strategy to treat autoimmune diseases, such as RA.

  • Phospholipase D1 deficiency in mice causes nonalcoholic fatty liver disease via an autophagy defect.
    Scientific reports, 2016
    Co-Authors: Jang Ho Hur, Gilbert Di Paolo, Sik Min, Claudia Dall'armi, Shi Young Park, Jae Sung Lee, Hui-young Lee, Mee Sup Yoon, Cheol Soo Choi
    Abstract:

    Nonalcoholic fatty liver disease (NAFLD) is characterized by the accumulation of triglycerides (TG) as lipid droplets in the liver. Although lipid-metabolizing enzymes are considered important in NAFLD, the involvement of Phospholipase D1 (PLD1) has not yet been studied. Here, we show that the genetic ablation of PLD1 in mice induces NAFLD due to an autophagy defect. PLD1 expression was decreased in high-fat diet-induced NAFLD. Subsequently, PLD1 deficiency led to an increase in hepatic TGs and liver weight. Autophagic flux was blocked in PlD1-/- hepatocytes, with decreased β-oxidation rate, reduced oxidation-related gene expression, and swollen mitochondria. The dynamics of autophagy was restored by treatment with the PLD product, phosphatidic acid (PA) or adenoviral PLD1 expression in PlD1-/- hepatocytes, confirming that lysosomal PA produced by PLD1 regulates autophagy. Notably, PLD1 expression in PlD1-/- liver significantly reduced hepatic lipid accumulation, compared with PlD1-/- liver. Thus, PLD1 plays an important role in hepatic steatosis via the regulation of autophagy.

Joong-soo Han - One of the best experts on this subject based on the ideXlab platform.

  • Therapeutic potential of a Phospholipase D1 inhibitory peptide fused with a cell-penetrating peptide as a novel anti-asthmatic drug in a Der f 2-induced airway inflammation model
    Experimental & molecular medicine, 2018
    Co-Authors: Yun Young Lee, Shin-young Park, Hye-jin Choi, So Young Lee, Eung-gook Kim, Joong-soo Han
    Abstract:

    Asthma is a chronic lung disease that causes airflow obstruction due to airway inflammation. However, its therapeutics remain inadequate. We previously reported that Phospholipase D1 (PLD1) is a key enzyme involved in the production of pro-inflammatory cytokines in airway inflammation induced by the house dust mite allergen Dermatophagoides farinae 2 (Der f 2). We also revealed that PLD1 is specifically inactivated by AP180 (assembly protein, 180 kDa) and identified the PLD1-specific binding motif (TVTSP) of AP180. Therefore, the aims of this study were to develop a novel anti-asthmatic agent that could suppress airway inflammation by inhibiting PLD1 and examine its acute and chronic toxicity. We designed TAT-TVTSP, a PLD1-inhibitory peptide fused with a cell-penetrating peptide (CPP) delivery system. TAT-TVTSP was efficiently delivered to bronchial epithelial cells and significantly reduced Der f 2-induced PLD activation and Interleukin 13 (IL-13) production. Intranasally administered TAT-TVTSP was also efficiently transferred to airway tissues and ameliorated airway inflammation in a Der f 2-induced allergic asthma mouse model. Moreover, we investigated the safety of TAT-TVTSP as a therapeutic agent through single- and repeated-dose toxicity studies in a mouse model. Taken together, these results indicated that a PLD1-inhibitory peptide fused with a cell-penetrating peptide may be useful for treating allergic inflammatory asthma induced by house dust mites (HDMs).

  • Phospholipase D1 Signaling: Essential Roles in Neural Stem Cell Differentiation
    Journal of Molecular Neuroscience, 2018
    Co-Authors: Shin-young Park, Joong-soo Han
    Abstract:

    Phospholipase D1 (PLD1) is generally accepted as playing an important role in the regulation of multiple cell functions, such as cell growth, survival, differentiation, membrane trafficking, and cytoskeletal organization. Recent findings suggest that PLD1 also plays an important role in the regulation of neuronal differentiation of neuronal cells. Moreover, PLD1-mediated signaling molecules dynamically regulate the neuronal differentiation of neural stem cells (NSCs). Rho family GTPases and Ca^2+-dependent signaling, in particular, are closely involved in PLD1-mediated neuronal differentiation of NSCs. Moreover, PLD1 has a significant effect on the neurogenesis of NSCs via the regulation of SHP-1/STAT3 activation. Therefore, PLD1 has now attracted significant attention as an essential neuronal signaling molecule in the nervous system. In the current review, we summarize recent findings on the regulation of PLD1 in neuronal differentiation and discuss the potential role of PLD1 in the neurogenesis of NSCs.

  • Cigarette smoke extract-induced interleukin-6 expression is regulated by Phospholipase D1 in human bronchial epithelial cells.
    The Journal of toxicological sciences, 2016
    Co-Authors: Jun Bon Koo, Joong-soo Han
    Abstract:

    Cigarette smoking is known to be associated with various kinds of diseases, including atherosclerotic cardiovascular disease, cancer, and chronic obstructive pulmonary disease (COPD). Many of the diseases associated with cigarette smoking are also associated with changes in interleukin-6 (IL-6) expression. In this study, we investigated the role of Phospholipase D1 (PLD1) in IL-6 expression induced by cigarette smoke extract (CSE). Treatment with CSE increased PLD1 and IL-6 expressions in human bronchial epithelial (BEAS-2B) cells. In addition, CSE treatment activated PLC, PKC, and MAPK pathway through the Gi protein-coupled receptor. Pertussis toxin (PTX, Gi protein-coupled receptor inhibitor), PAO (PLC inhibitor), Go6976 (PKC inhibitor) and SB203580 (p38MAPK inhibitor) decreased CSE-induced PLD1 expression. The results show that Gi protein, PLC, PKC, and p38MAPK act as upstream regulators of PLD1 in CSE-treated BEAS-2B cells. Moreover, PLD1 siRNA transfection decreased CSE-induced ATF2 phosphorylation and IL-6 expression. In addition, inhibitors of Gi protein, PLC, PKC, and p38MAPK, and ATF2 siRNA transfection decreased CSE-induced IL-6 expression, suggesting that CSE-induced IL-6 expression is regulated via Gi protein/PLC/PKC/p38MAPK/PLD1/ATF2 pathway. Taken together, the results suggest that PLD1 is an important regulator of IL-6 expression induced by CSE in BEAS-2B cells.

  • Leptin increases TNF-α expression and production through Phospholipase D1 in Raw 264.7 cells.
    PloS one, 2014
    Co-Authors: Se-min Lee, Hye-jin Choi, Joong-soo Han
    Abstract:

    Epidemiological evidence suggests that obesity is associated with inflammation of the respiratory tract and the pathogenesis of asthma. The purpose of this study was to examine the role of Phospholipase D1 (PLD1) in leptin-induced expression of the proinflammatory cytokine, tumor necrosis factor (TNF)-α, and to suggest a molecular link between obesity and respiratory tract inflammation. We investigated whether leptin, a typical adipocytokine, plays a role in the expression of TNF-α through increased PLD1 activity in Raw 264.7. Leptin enhanced the activity of PLD1 through activation of PLCγ and Src, while PLD1 siRNA decreased the leptin-induced expression and production of TNF-α. Leptin-induced PLD activation was also inhibited by a PLCγ inhibitor (PAO) and Src kinase inhibitor (PP2), indicating that PLCγ and Src kinase are upstream activators of PLD1. Down-regulation of PLD1 also completely blocked activation of p70S6K, an activator of JNK. Leptin-induced expression of TNF-α was also prevented by inhibition of p70S6K and JNK. Taken together, these results indicate that PLD1 acts as an important regulator of leptin-induced expression of TNF-α by participating in the PLCγ/Src/PLD1/PA/p70S6K/JNK pathway.

  • Phospholipase D1 increases Bcl-2 expression during neuronal differentiation of rat neural stem cells.
    Molecular neurobiology, 2014
    Co-Authors: Shin-young Park, Sung Nyo Yoon, Min Jeong Kang, Joong-soo Han
    Abstract:

    We studied the possible role of Phospholipase D1 (PLD1) in the neuronal differentiation, including neurite formation of neural stem cells. PLD1 protein and PLD activity increased during neuronal differentiation. Bcl-2 also increased. Downregulation of PLD1 by transfection with PLD1 siRNA or a dominant-negative form of PLD1 (DN-PLD1) inhibited both neurite outgrowth and Bcl-2 expression. PLD activity was dramatically reduced by a PLCγ (Phospholipase Cγ) inhibitor (U73122), a Ca(2+)chelator (BAPTA-AM), and a PKCα (protein kinase Cα) inhibitor (RO320432). Furthermore, treatment with arachidonic acid (AA) which is generated by the action of PLA2 (Phospholipase A2) on phosphatidic acid (a PLD1 product), increased the phosphorylation of p38 MAPK and CREB, as well as Bcl-2 expression, indicating that PLA2 is involved in the differentiation process resulting from PLD1 activation. PGE2 (prostaglandin E2), a cyclooxygenase product of AA, also increased during neuronal differentiation. Moreover, treatment with PGE2 increased the phosphorylation of p38 MAPK and CREB, as well as Bcl-2 expression, and this effect was inhibited by a PKA inhibitor (Rp-cAMP). As expected, inhibition of p38 MAPK resulted in loss of CREB activity, and when CREB activity was blocked with CREB siRNA, Bcl-2 production also decreased. We also showed that the EP4 receptor was required for the PKA/p38MAPK/CREB/Bcl-2 pathway. Taken together, these observations indicate that PLD1 is activated by PLCγ/PKCα signaling and stimulate Bcl-2 expression through PLA2/Cox2/EP4/PKA/p38MAPK/CREB during neuronal differentiation of rat neural stem cells.

John H. Exton - One of the best experts on this subject based on the ideXlab platform.

  • A point mutation at phenylalanine 663 abolishes protein kinase C alpha's ability to translocate to the perinuclear region and activate Phospholipase D1
    Biochemical and biophysical research communications, 2005
    Co-Authors: John H. Exton
    Abstract:

    Abstract Previous research showed that protein kinase Cα (PKCα) translocated to the perinuclear region and activated Phospholipase D1, but the mechanism involved was not clear. Here, we provide evidence that Phe 663 (the 10th amino acid from C-terminus) of PKCα is essential for its translocation. A point mutation (F663D) completely blocked PKCα’s binding to and activation of Phospholipase D1. Further studies showed that deletion of the C-terminal nine amino acids of PKCα did not alter its translocation to the perinuclear region but deletion of the C-terminal 10 amino acids and the F663D mutation abolished this translocation. The F663D mutant was found to be resistant to dephosphorylation, which might account for its inability to translocate to the perinuclear region and activate PLD1, since dephosphorylation of PKCα is required for its relocation from plasma membrane to the perinuclear region.

  • Requirement of Phospholipase D1 activity in H-RasV12-induced transformation
    Proceedings of the National Academy of Sciences of the United States of America, 2005
    Co-Authors: F. Gregory Buchanan, Matt Mcreynolds, Anthony D. Couvillon, Yoonseok Kam, Vijaykumar R. Holla, Raymond N. Dubois, John H. Exton
    Abstract:

    The ability of the Ras oncogene to transform normal cells has been well established. One downstream effector of Ras is the lipid hydrolyzing enzyme Phospholipase D. Recent evidence has emerged indicating a role for Phospholipase D in cell proliferation, membrane trafficking, and migration. To study the potential importance of Phospholipase D in the oncogenic ability of Ras, we used Rat-2 fibroblasts with reduced Phospholipase D1 activity (Rat-2V25). Here, we show that H-Ras transformation of Rat-2 fibroblasts requires normal Phospholipase D1 activity. WT Rat-2 fibroblasts transfected with the H-RasV12 oncogene grew colonies in soft agar and tumors in nude mice. However, Rat-2V25 cells when transfected with the H-RasV12 oncogene did not form colonies in soft agar or produce tumors when xenografted onto nude mice. Interestingly, in the presence of phosphatidic acid, the product of Phospholipase D, growth in soft agar and tumor formation was restored. We also observed a dramatic increase in the expression of Phospholipase D1 in colorectal tumors when compared with adjacent normal mucosa. Our studies identify Phospholipase D1 as a critical downstream mediator of H-Ras-induced tumor formation.

  • Tyrosine phosphorylation of Phospholipase D1 by v-Src does not per se result in activation.
    Cellular signalling, 2005
    Co-Authors: Zhi Xie, Zhizhuang Joe Zhao, John H. Exton
    Abstract:

    The relationship between tyrosine phosphorylation and activation of Phospholipase D1 (PLD1) by v-Src was examined. Co-expression of v-Src and PLD1 in COS-7 cells resulted in increased activity and marked tyrosine phosphorylation of PLD1. PLD activity was increased in membranes or immunoprecipitates prepared from these cells. Dephosphorylation of the immunoprecipitated enzyme by tyrosine phosphatase or phosphorylation by c-Src produced no changes in its activity. Tyrosine phosphorylation induced by v-Src caused a shift of the enzyme from the Triton-soluble to the Triton-insoluble fraction. v-Src and PLD1 could be co-immunoprecipitated from cells co-expressing these and were co-localized in the perinuclear region as assessed by immunofluorescence. Mutation of the palmitoylation sites of PLD1 significantly reduced tyrosine phosphorylation by v-Src. It is concluded that tyrosine phosphorylation of PLD1 by v-Src does not per se alter its activity. It is proposed that activation of PLD1 by v-Src in vivo may involve association/colocalization of the two proteins.

  • Protein Kinase Cα Translocates to the Perinuclear Region to Activate Phospholipase D1
    The Journal of biological chemistry, 2004
    Co-Authors: John H. Exton
    Abstract:

    The inhibition of phorbol ester activation of Phospholipase D1 (PLD1) by protein kinase C (PKC) inhibitors has been considered proof of phosphorylation-dependent activation of PLD1 by PKCalpha. We studied the effect of the PKC inhibitors Ro-31-8220 and bisindolylmaleimide I on PLD1 activation and found that they inhibited the activation by interfering with PKCalpha binding to PLD1. Further studies showed that only unphosphorylated PKCalpha could bind to and activate PLD1 and that both inhibitors induced phosphorylation of PKCalpha. The phosphorylation status of either PLD1 or PKCalpha per se did not affect PLD1 activation in vitro. Immunofluorescence studies showed that PLD1 remained in the perinuclear region after phorbol ester treatment, whereas PKCalpha translocated from cytosol to both plasma membrane and perinuclear regions. Both Ro-31-8220 and bisindolylmaleimide I blocked the translocation of PKCalpha to the perinuclear region but not to the plasma membrane. Studies with okadaic acid suggested that phosphorylation regulated the relocation of PKCalpha from the plasma membrane to the perinuclear region. It is proposed that localization and interaction of PKCalpha with PLD1 in the perinuclear region is required for PLD1 activation and that PKC inhibitors inhibit this through phosphorylation of PKCalpha, which blocks its translocation.

  • Mechanisms of Regulation of Phospholipase D1 by Protein Kinase Cα
    The Journal of biological chemistry, 2002
    Co-Authors: John H. Exton
    Abstract:

    Abstract It has been suggested that protein-protein interaction is important for protein kinase C (PKC) α to activate Phospholipase D1 (PLD1). To determine the one or more sites on PKCα that are involved in binding to PLD1, fragments containing the regulatory domain, catalytic domain, and C1–C3 domain of PKCα were constructed and shown to be functional, but they all failed to bind and activate PLD1 in vivo and in vitro. A C-terminal 23-amino acid (aa) deletion mutant of PKCα was also found to be inactive. To define the binding/activation site(s) in the C terminus of PKCα, 1- to 11-aa deletion mutants were made in this terminus. Deletion of up to 9 aa did not alter the ability of PKCα to bind and activate PLDl, whereas a 10-aa deletion was inactive. The residue at position 10 was Phe663. Mutations of this residue (F663D and F663A) caused loss of binding, activation, and phosphorylation of PLD1, indicating that Phe663 is essential for these activities. Time course experiments showed that the activation of PLD1 by PMA was much faster than its phosphorylation, and its activity decreased as phosphorylation increased with time. Staurosporine, a PKC inhibitor, completely inhibited PLD1 phosphorylation in response to 4β-phorbol 12-myristate 13-acetate PMA and blocked the later decrease in PLD activity. The same results were found with the D481E mutant of PKCα, which is unable to phosphorylate PLD1. These results indicate that neither the regulatory nor catalytic domains of PKCα alone can bind to or activate PLD1 and that a residue in the C terminus of PKCα (Phe663) is required for these effects. The initial activation of PLD1 by PMA is highly correlated with the binding of PKCα. Although PKCα can phosphorylate PLD1, this is a relatively slow process and is associated with inactivation of the enzyme.

Michael A. Frohman - One of the best experts on this subject based on the ideXlab platform.

  • Phospholipase D1 facilitates second phase myoblast fusion and skeletal muscle regeneration
    Molecular biology of the cell, 2014
    Co-Authors: Shuzhi Teng, Tsunaki Hongu, Qin Chen, Michael A. Frohman, Yasunori Kanaho, David Stegner, Hiroshi Hasegawa, Li Chen, Bernhard Nieswandt, Ping Huang
    Abstract:

    Myoblast differentiation and fusion is a well-orchestrated multistep process that is essential for skeletal muscle development and regeneration. Phospholipase D1 (PLD1) has been implicated in the initiation of myoblast differentiation in vitro. However, whether PLD1 plays additional roles in myoblast fusion and exerts a function in myogenesis in vivo remains unknown. Here we show that PLD1 expression is up-regulated in myogenic cells during muscle regeneration after cardiotoxin injury and that genetic ablation of PLD1 results in delayed myofiber regeneration. Myoblasts derived from PLD1-null mice or treated with PLD1-specific inhibitor are unable to form mature myotubes, indicating defects in second-phase myoblast fusion. Concomitantly, the PLD1 product phosphatidic acid is transiently detected on the plasma membrane of differentiating myocytes, and its production is inhibited by PLD1 knockdown. Exogenous lysophosphatidylcholine, a key membrane lipid for fusion pore formation, partially rescues fusion defect resulting from PLD1 inhibition. Thus these studies demonstrate a role for PLD1 in myoblast fusion during myogenesis in which PLD1 facilitates the fusion of mononuclear myocytes with nascent myotubes.

  • Cellular and physiological roles for Phospholipase D1 in cancer.
    The Journal of biological chemistry, 2014
    Co-Authors: Yi Zhang, Michael A. Frohman
    Abstract:

    Phospholipase D enzymes have long been proposed to play multiple cell biological roles in cancer. With the generation of Phospholipase D1 (PLD1)-deficient mice and the development of small molecule PLD-specific inhibitors, in vivo roles for PLD1 in cancer are now being defined, both in the tumor cells and in the tumor environment. We review here tools now used to explore in vivo roles for PLD1 in cancer and summarize recent findings regarding functions in angiogenesis and metastasis.

  • Presenilin-1 uses Phospholipase D1 as a negative regulator of β-amyloid formation
    Proceedings of the National Academy of Sciences of the United States of America, 2006
    Co-Authors: Dongming Cai, Michael A. Frohman, William J. Netzer, Minghao Zhong, Yixin Lin, David A. Foster, Sangram S. Sisodia, Fred S. Gorelick
    Abstract:

    Presenilin (PS1/PS2) is a major component of γ-secretase, the activity that mediates proteolysis of β-amyloid precursor protein to generate β-amyloid (Aβ). Here we demonstrate that PS1, through its loop region, binds to Phospholipase D1 (PLD1), thereby recruiting it to the Golgi/trans-Golgi network. Overexpression of wild-type PLD1 reduces Aβ generation. Conversely, down-regulation of endogenous PLD1 by small hairpin RNA elevates Aβ production. The Aβ-lowering effect of PLD1 is independent of its ability to promote vesicular budding of β-amyloid precursor protein. The data indicate that overexpression of PLD1 decreases, and down-regulation of PLD1 increases, the catalytic activity, and the association of the subunits, of γ-secretase.

  • Peroxiredoxin II functions as a signal terminator for H2O2-activated Phospholipase D1
    The FEBS journal, 2005
    Co-Authors: Nianzhou Xiao, Michael A. Frohman
    Abstract:

    Phospholipase D1 (PLD1) is a signal-transduction regulated enzyme which regulates several cell intrinsic processes including activation of NAPDH oxidase, which elevates intracellular H2O2. Several proteins have been reported to interact with PLD1 in resting cells. We sought to identify proteins that interact with PLD1 after phorbol 12-myristate 13-acetate (PMA) stimulation. A novel interaction with peroxiredoxin II (PrxII), an enzyme that eliminates cellular H2O2, which is a known stimulator of PLD1, was identified by PLD1-affinity pull-down and MS. PMA stimulation was confirmed to promote physical interaction between PLD1 and PrxII and to cause PLD1 and PrxII to colocalize subcellularly. Functional significance of the interaction was suggested by the observation that over-expression of PrxII specifically reduces the response of PLD1 to stimulation by H2O2. These results indicate that PrxII may have a signal-terminating role for PLD1 by being recruited to sites containing activated PLD1 after cellular stimulation involving production of H2O2.

  • Phospholipase D1-Promoted Release of Tissue Plasminogen Activator Facilitates Neurite Outgrowth
    The Journal of neuroscience : the official journal of the Society for Neuroscience, 2005
    Co-Authors: Yan Zhang, Michael A. Frohman, Yasunori Kanaho, Stella E. Tsirka
    Abstract:

    Temporal lobe epilepsy (TLE) is the most common form of epilepsy, affecting ∼1-2% of the population. Seizure events resulting from TLE are characterized by aberrant hippocampal mossy fiber sprouting and plastic responses that affect brain function. Seizure susceptibility is modulated by the enzyme tissue plasminogen activator (tPA), the normal physiological role of which includes promotion of synaptic reorganization in the mossy fiber pathway by initiating a proteolytic cascade that cleaves extracellular matrix components and influences neurite extension. tPA is concentrated at and selectively secreted from growth cones during excitatory events. However, the mechanisms underlying tPA release during seizure-induced synaptogenesis are not well understood. We examine here potential roles for the signaling enzyme Phospholipase D1 (PLD1), which promotes regulated exocytosis in non-CNS cell types, and which we previously demonstrated increases in expression in hippocampal neurons during seizure-induced mossy fiber sprouting. We now show that overexpression of wild-type PLD1 in cultured neurons promotes tPA release and tPA-dependent neurite extension, whereas overexpression of an inactive PLD1 allele or pharmacological inhibition of PLD1 inhibits tPA release. Similarly, viral delivery of wild-type PLD1 into the hippocampus facilitates tPA secretion and mossy fiber sprouting in a seizure-inducing model, whereas the inactive PLD1 allele inhibits tPA release and elicits blunted and abnormal mossy fiber extension similar to that observed for tPA-/- mice. Together, these findings secretion and thus mossy fiber extension in the setting of elevated suggest that PLD1 functions endogenously to regulate tPA-/- neuronal stimulation, such as that seen in TLE.

Sung Ho Ryu - One of the best experts on this subject based on the ideXlab platform.

  • Phospholipase D1 mediates AMP-activated protein kinase signaling for glucose uptake.
    PloS one, 2010
    Co-Authors: Jong Hyun Kim, Pann-ghill Suh, Ji Man Park, Kyungmoo Yea, Hyun Wook Kim, Sung Ho Ryu
    Abstract:

    Background Glucose homeostasis is maintained by a balance between hepatic glucose production and peripheral glucose utilization. In skeletal muscle cells, glucose utilization is primarily regulated by glucose uptake. Deprivation of cellular energy induces the activation of regulatory proteins and thus glucose uptake. AMP-activated protein kinase (AMPK) is known to play a significant role in the regulation of energy balances. However, the mechanisms related to the AMPK-mediated control of glucose uptake have yet to be elucidated. Methodology/principal findings Here, we found that AMPK-induced Phospholipase D1 (PLD1) activation is required for (14)C-glucose uptake in muscle cells under glucose deprivation conditions. PLD1 activity rather than PLD2 activity is significantly enhanced by glucose deprivation. AMPK-wild type (WT) stimulates PLD activity, while AMPK-dominant negative (DN) inhibits it. AMPK regulates PLD1 activity through phosphorylation of the Ser-505 and this phosphorylation is increased by the presence of AMP. Furthermore, PLD1-S505Q, a phosphorylation-deficient mutant, shows no changes in activity in response to glucose deprivation and does not show a significant increase in (14)C-glucose uptake when compared to PLD1-WT. Taken together, these results suggest that phosphorylation of PLD1 is important for the regulation of (14)C-glucose uptake. In addition, extracellular signal-regulated kinase (ERK) is stimulated by AMPK-induced PLD1 activation through the formation of phosphatidic acid (PA), which is a product of PLD. An ERK pharmacological inhibitor, PD98059, and the PLD inhibitor, 1-BtOH, both attenuate (14)C-glucose uptake in muscle cells. Finally, the extracellular stresses caused by glucose deprivation or aminoimidazole carboxamide ribonucleotide (AICAR; AMPK activator) regulate (14)C-glucose uptake and cell surface glucose transport (GLUT) 4 through ERK stimulation by AMPK-mediated PLD1 activation. Conclusions/significance These results suggest that AMPK-mediated PLD1 activation is required for (14)C-glucose uptake through ERK stimulation. We propose that the AMPK-mediated PLD1 pathway may provide crucial clues to understanding the mechanisms involved in glucose uptake.

  • Phospholipase D1 is phosphorylated and activated by protein kinase C in caveolin-enriched microdomains within the plasma membrane.
    The Journal of biological chemistry, 2000
    Co-Authors: Yong Kim, Jae Ho Kim, Jung Min Han, Pann-ghill Suh, Byung Ryul Han, Kyung Ah Lee, Byoung Dae Lee, Il Ho Jang, Sung Ho Ryu
    Abstract:

    Abstract Activities of Phospholipase D (PLD) in diverse subcellular organelles have been identified but the details of regulatory mechanisms in such locations are unknown. Protein kinase C (PKC) is a major regulator of PLD. Serine 2, threonine 147, and serine 561 residues of Phospholipase D1 (PLD1) were determined as sites of phosphorylation by PKC (Kim, Y., Han, J. M., Park, J. B., Lee, S. D., Oh, Y. S., Chung, C., Lee, T. G., Kim, J. H., Park, S. K., Yoo, J. S., Suh, P. G., Ryu, S. H. (1999) Biochemistry 38, 10344–10351). In our present study, a triple mutation of these phosphorylation sites diminished markedly phorbol 12-myristate 13-acetate (PMA)-induced PLD1 activity in COS-7 cells. We looked at the location of the PLD1 phosphorylation by PKC by observing PMA induced band shifts and by use of anti-phospho-PLD1 monoclonal antibody. The shifted PMA-induced proteins and the immunoreactivity of the anti-phospho-PLD1 antibody were mainly found in the caveolin-enriched membrane (CEM) fraction. Depletion of cellular cholesterol led to a loss of this compartmentalization of phosphorylated PLD1 in the CEM. Replacement of the cellular cholesterol led to the restoration of phosphorylated PLD1 in the CEM. Immunocytochemical studies of COS-7 cells revealed that PLD1 was localized in the plasma membrane as well as in the vesicular structures in the cytoplasm, but the phosphorylation of PLD1 occurred only in the plasma membrane. Our results, therefore, show that phosphorylation, and thereby activation, of PLD1 by PKC occurs in the caveolin and cholesterol-enriched low density domain of the plasma membrane in COS-7 cells.

  • Independent Functioning of Cytosolic Phospholipase A2 and Phospholipase D1 in Trp-Lys-Tyr-Met-Val-D-Met-Induced Superoxide Generation in Human Monocytes
    Journal of immunology (Baltimore Md. : 1950), 2000
    Co-Authors: Yoe-sik Bae, Jae Ho Kim, Yong Kim, Taehoon Lee, Pann-ghill Suh, Youndong Kim, Sung Ho Ryu
    Abstract:

    Recently, a novel peptide (Trp-Lys-Tyr-Met-Val-D-Met, WKYMVm) has been shown to induce superoxide generation in human monocytes. The peptide stimulated Phospholipase A2 (PLA2) activity in a concentration- and time-dependent manner. Superoxide generation as well as arachidonic acid (AA) release evoked by treatment with WKYMVm could be almost completely blocked by pretreatment of the cells with cytosolic PLA2 (cPLA2)-specific inhibitors. The involvement of cPLA2 in the peptide-induced AA release was further supported by translocation of cPLA2 to the nuclear membrane of monocytes incubated with WKYMVm. WKYMVm-induced phosphatidylbutanol formation was completely abolished by pretreatment with PKC inhibitors. Immunoblot showed that monocytes express Phospholipase D1 (PLD1), but not PLD2. GF109203X as well as butan-1-ol inhibited peptide-induced superoxide generation in monocytes. Furthermore, the interrelationship between the two Phospholipases, cPLA2 and PLD1, and upstream signaling molecules involved in WKYMVm-dependent activation was investigated. The inhibition of cPLA2 did not blunt peptide-stimulated PLD1 activation or vice versa. Intracellular Ca2+ mobilization was indispensable for the activation of PLD1 as well as cPLA2. The WKYMVm-dependent stimulation of cPLA2 activity was partially dependent on the activation of PKC and mitogen-activated protein kinase, while PKC activation, but not mitogen-activated protein kinase activation, was an essential prerequisite for stimulation of PLD1. Taken together, activation of the two Phospholipases, which are absolutely required for superoxide generation, takes place through independent signaling pathways that diverge from a common pathway at a point downstream of Ca2+.

  • Dual requirement for rho and protein kinase C in direct activation of Phospholipase D1 through G protein-coupled receptor signaling.
    Molecular biology of the cell, 2000
    Co-Authors: Yelena M. Altshuller, Andrew J. Morris, Yong Kim, Jung Min Han, Sung Ho Ryu, Michael A. Frohman
    Abstract:

    G protein-coupled and tyrosine kinase receptor activation of Phospholipase D1 (PLD1) play key roles in agonist-stimulated cellular responses such as regulated exocytosis, actin stress fiber formation, and alterations in cell morphology and motility. Protein Kinase C, ADP-ribosylation factor (ARF), and Rho family members activate PLD1 in vitro; however, the actions of the stimulators on PLD1 in vivo have been proposed to take place through indirect pathways. We have used the yeast split-hybrid system to generate PLD1 alleles that fail to bind to or to be activated by RhoA but that retain wild-type responses to ARF and PKC. These alleles then were employed in combination with alleles unresponsive to PKC or to both stimulators to examine the activation of PLD1 by G protein-coupled receptors. Our results demonstrate that direct stimulation of PLD1 in vivo by RhoA (and by PKC) is critical for significant PLD1 activation but that PLD1 subcellular localization and regulated phosphorylation occur independently of these stimulatory pathways.

  • Phospholipase D1 in Caveolae: Regulation by Protein Kinase Cα and Caveolin-1†
    Biochemistry, 1999
    Co-Authors: Jae Ho Kim, Jong Bae Park, Sang Do Lee, Yong Kim, Jung Min Han, Taehoon Lee, Pann-ghill Suh, Sukmook Lee, Sung Ho Ryu
    Abstract:

    Caveolae are small plasma membrane invaginations that have been implicated in cell signaling, and caveolin is a principal structural component of the caveolar membrane. Previously we have demonstrated that protein kinase Cα (PKCα) directly interacts with Phospholipase D1 (PLD1), activating the enzymatic activity of PLD1 in the presence of phorbol 12-myristate 13-acetate (PMA) [Lee, T. G., et al. (1997) Biochim. Biophys. Acta 1347, 199−204]. In this study, using a detergent-free procedure for the purification of a caveolin-enriched membrane fraction (CEM) and immunoblot analysis, we show that PLD1 is enriched in the CEMs of 3Y1 rat fibroblasts. Purified PLD1 directly bound to a glutathione S-transferase−caveolin-1 fusion protein in in vitro binding assays. The association of PLD1 with caveolin-1 could be completely eliminated by preincubation of PLD1 with an oligopeptide corresponding to the scaffolding domain (amino acids 82−101) of caveolin-1, indicating that caveolin-1 interacts with PLD1 through the sc...