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Bogdanova OV, Kot LI, Lavrova KV, Bogdanov VB, Sloan EK, Beregova TV, Ostapchenko LI. Modulation of protein tyrosine phosphorylation in gastric mucosa during re-epithelization processes. World J Biol Chem 2010; 1:338-47. [PMID: 21537468 PMCID: PMC3083939 DOI: 10.4331/wjbc.v1.i11.338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 09/13/2010] [Accepted: 09/20/2010] [Indexed: 02/05/2023] Open
Abstract
AIM: To investigate the role of protein tyrosine phosphorylation in gastric wound formation and repair following ulceration.
METHODS: Gastric lesions were induced in rats using restraint cold stress. To investigate the effect of oxidative and nitrosative cell stress on tyrosine phosphorylation during wound repair, total activity of protein tyrosine kinase (PTK), protein tyrosine phosphatase (PTP), antioxidant enzymes, nitric oxide synthase (NOS), 2’,5’-oligoadenylate synthetase, hydroxyl radical and zinc levels were assayed in parallel.
RESULTS: Ulcer provocation induced an immediate decrease in tyrosine kinase (40% in plasma membranes and 56% in cytosol, P < 0.05) and phosphatase activity (threefold in plasma membranes and 3.3-fold in cytosol), followed by 2.3-2.4-fold decrease (P < 0.05) in protein phosphotyrosine content in the gastric mucosa. Ulceration induced no immediate change in superoxide dismutase (SOD) activity, 30% increase (P < 0.05) in catalase activity, 2.3-fold inhibition (P < 0.05) of glutathione peroxidase, 3.3-fold increase (P < 0.05) in hydroxyl radical content, and 2.3-fold decrease (P < 0.05) in zinc level in gastric mucosa. NOS activity was three times higher in gastric mucosa cells after cold stress. Following ulceration, PTK activity increased in plasma membranes and reached a maximum on day 4 after stress (twofold increase, P < 0.05), but remained inhibited (1.6-3-fold decrease on days 3, 4 and 5, P < 0.05) in the cytosol. Tyrosine phosphatases remained inhibited both in membranes and cytosol (1.5-2.4-fold, P < 0.05). NOS activity remained increased on days 1, 2 and 3 (3.8-, 2.6-, 2.2-fold, respectively, P < 0.05). Activity of SOD increased 1.6 times (P < 0.05) days 4 and 5 after stress. Catalase activity normalized after day 2. Glutathione peroxidase activity and zinc level decreased (3.3- and 2-fold, respectively, P < 0.05) on the last day. Activity of 2’,5’-oligoadenylate synthethase increased 2.8-fold (P < 0.05) at the beginning, and 1.6-2.3-fold (P < 0.05) during ulcer recuperation, and normalized on day 5, consistent with slowing of inflammation processes.
CONCLUSION: These studies show diverse changes in total tyrosine kinase activity in gastric mucosa during the recovery process. Oxidative and nitrosative stress during lesion formation might lead to the observed reduction in tyrosine phosphorylation during ulceration.
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Sato K, Okajima F. Role of sphingosine 1-phosphate in anti-atherogenic actions of high-density lipoprotein. World J Biol Chem 2010; 1:327-37. [PMID: 21537467 PMCID: PMC3083937 DOI: 10.4331/wjbc.v1.i11.327] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 08/31/2010] [Accepted: 09/07/2010] [Indexed: 02/05/2023] Open
Abstract
The reverse cholesterol transport mediated by high-density lipoprotein (HDL) is an important mechanism for maintaining body cholesterol, and hence, the crucial anti-atherogenic action of the lipoprotein. Recent studies, however, have shown that HDL exerts a variety of anti-inflammatory and anti-atherogenic actions independently of cholesterol metabolism. The present review provides an overview of the roles of sphingosine 1-phosphate (S1P)/S1P receptor and apolipoprotein A-I/scavenger receptor class B type I systems in the anti-atherogenic HDL actions. In addition, the physiological significance of the existence of S1P in the HDL particles is discussed.
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Brocklyn JRV. Regulation of cancer cell migration and invasion by sphingosine-1-phosphate. World J Biol Chem 2010; 1:307-12. [PMID: 21537464 PMCID: PMC3083934 DOI: 10.4331/wjbc.v1.i10.307] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 07/28/2010] [Accepted: 08/04/2010] [Indexed: 02/05/2023] Open
Abstract
Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid that has been implicated in regulation of a number of cancer cell malignant behaviors, including cell proliferation, survival, chemotherapeutic resistance and angiogenesis. However, the effects of S1P on cancer cell migration, invasion and metastasis, are perhaps its most complex, due to the fact that, depending upon the S1P receptors that mediate its responses and the crosstalk with other signaling pathways, S1P can either positively or negatively regulate invasion. This review summarizes the effects of S1P on cancer cell invasion and the mechanisms by which it affects this important aspect of cancer cell behavior.
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229
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Takuwa Y, Du W, Qi X, Okamoto Y, Takuwa N, Yoshioka K. Roles of sphingosine-1-phosphate signaling in angiogenesis. World J Biol Chem 2010; 1:298-306. [PMID: 21537463 PMCID: PMC3083935 DOI: 10.4331/wjbc.v1.i10.298] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 09/15/2010] [Accepted: 09/22/2010] [Indexed: 02/05/2023] Open
Abstract
Sphingosine-1-phosphate (S1P) is a blood-borne lipid mediator with pleiotropic biological activities. S1P acts via the specific cell surface G-protein-coupled receptors, S1P1-5. S1P1 and S1P2 were originally identified from vascular endothelial cells (ECs) and smooth muscle cells, respectively. Emerging evidence shows that S1P plays crucial roles in the regulation of vascular functions, including vascular formation, barrier protection and vascular tone via S1P1, S1P2 and S1P3. In particular, S1P regulates vascular formation through multiple mechanisms; S1P exerts both positive and negative effects on angiogenesis and vascular maturation. The positive and negative effects of S1P are mediated by S1P1 and S1P2, respectively. These effects of S1P1 and S1P2 are probably mediated by the S1P receptors expressed in multiple cell types including ECs and bone-marrow-derived cells. The receptor-subtype-specific, distinct effects of S1P favor the development of novel therapeutic tactics for antitumor angiogenesis in cancer and therapeutic angiogenesis in ischemic diseases.
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230
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Wu S. Localization and function of a eukaryotic-initiation-factor-2-associated 67-kDa glycoprotein. World J Biol Chem 2010; 1:313-20. [PMID: 21537465 PMCID: PMC3083933 DOI: 10.4331/wjbc.v1.i10.313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 08/19/2010] [Accepted: 08/26/2010] [Indexed: 02/05/2023] Open
Abstract
AIM: To study the localization and function of a eukaryotic initiation factor 2 (eIF2α)-associated 67-kDa glycoprotein (p67).
METHODS: Immunofluorescence staining, 35S-Met/Cys metabolic labeling, Western blotting analysis, sucrose gradient centrifugation and high speed centrifugation were used to determine the localization of proteins in transiently transfected COS-1 cells. Transient co-transfection followed by co-immunoprecipitation was used to study the interaction between p67 and double-stranded RNA (dsRNA)-dependent protein kinase (PKR). Wheat germ agglutinin agarose beads were used to absorb glycosylated proteins. In vivo32P-labeling followed by immunoprecipitation and Western blotting were used to measure PKR autophosphorylation, eIF2α phosphorylation, and p67 expression in normal and breast cancer cells.
RESULTS: The image from immunofluorescence staining showed that p67 was overexpressed in the cytosol but not in the nucleus. In a sucrose gradient, approximately 30% of the overexpressed p67 was bound with ribosomes. p67 interacted with the kinase domain, but not the dsRNA-binding domains of PKR. Only the glycosylated p67 was associated with the ribosome, and p67 did not compete with PKR for ribosome binding. In breast cancer cells, there was increased autophosphorylation of PKR but no phosphorylation of eIF2α, compared with normal breast cells.α The ratio of glycosylated/deglycosylated p67 was altered in breast cancer cells.
CONCLUSION: Glycosylation of p67 is required for its ribosomal association and can potentially inhibit PKR via interaction with the kinase domain of PKR.
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Argraves KM, Wilkerson BA, Argraves WS. Sphingosine-1-phosphate signaling in vasculogenesis and angiogenesis. World J Biol Chem 2010; 1:291-7. [PMID: 21537462 PMCID: PMC3083932 DOI: 10.4331/wjbc.v1.i10.291] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 08/29/2010] [Accepted: 09/05/2010] [Indexed: 02/05/2023] Open
Abstract
Blood vessels either form de novo through the process of vasculogenesis or through angiogenesis that involves the sprouting and proliferation of endothelial cells in pre-existing blood vessels. A complex interactive network of signaling cascades downstream from at least three of the nine known G-protein-coupled sphingosine-1-phosphate (S1P) receptors act as a prime effector of neovascularization that occurs in embryonic development and in association with various pathologies. This review focuses on the current knowledge of the roles of S1P signaling in vasculogenesis and angiogenesis, with particular emphasis on vascular cell adhesion and motility responses.
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232
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Lei B. Benfang Lei’s research on heme acquisition in Gram-positive pathogens and bacterial pathogenesis. World J Biol Chem 2010; 1:286-90. [PMID: 21537486 PMCID: PMC3083973 DOI: 10.4331/wjbc.v1.i9.286] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2010] [Revised: 08/20/2010] [Accepted: 08/27/2010] [Indexed: 02/05/2023] Open
Abstract
Benfang Lei’s laboratory conducts research on pathogenesis of human pathogen Group A Streptococcus (GAS) and horse pathogen Streptococcus equi (S. equi). His current research focuses on heme acquisition in Gram-positive pathogens and molecular mechanism of GAS and S. equi pathogenesis. Heme is an important source of essential iron for bacterial pathogens. Benfang Lei and colleagues identified the first cell surface heme-binding protein in Gram-positive pathogens and the heme acquisition system in GAS, demonstrated direct heme transfer from one protein to another, demonstrated an experimental pathway of heme acquisition by the Staphylococcus aureus Isd system, elucidated the activated heme transfer mechanism, and obtained evidence for a chemical mechanism of direct axial ligand displacement during the Shp-to-HtsA heme transfer reaction. These findings have considerably contributed to the progress that has been made over recent years in understanding the heme acquisition process in Gram-positive pathogens. Pathogenesis of GAS is mediated by an abundance of extracellular proteins, and pathogenic role and functional mechanism are not known for many of these virulence factors. Lei laboratory identified a secreted protein of GAS as a CovRS-regulated virulence factor that is a protective antigen and is critical for GAS spreading in the skin and systemic dissemination. These studies may lead to development of novel strategies to prevent and treat GAS infections.
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233
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Zaidi A. Plasma membrane Ca 2+-ATPases: Targets of oxidative stress in brain aging and neurodegeneration. World J Biol Chem 2010; 1:271-80. [PMID: 21537484 PMCID: PMC3083975 DOI: 10.4331/wjbc.v1.i9.271] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 08/20/2010] [Accepted: 08/27/2010] [Indexed: 02/05/2023] Open
Abstract
The plasma membrane Ca2+-ATPase (PMCA) pumps play an important role in the maintenance of precise levels of intracellular Ca2+ [Ca2+]i, essential to the functioning of neurons. In this article, we review evidence showing age-related changes of the PMCAs in synaptic plasma membranes (SPMs). PMCA activity and protein levels in SPMs diminish progressively with increasing age. The PMCAs are very sensitive to oxidative stress and undergo functional and structural changes when exposed to oxidants of physiological relevance. The major signatures of oxidative modification in the PMCAs are rapid inactivation, conformational changes, aggregation, internalization from the plasma membrane and proteolytic degradation. PMCA proteolysis appears to be mediated by both calpains and caspases. The predominance of one proteolytic pathway vs the other, the ensuing pattern of PMCA degradation and its consequence on pump activity depends largely on the type of insult, its intensity and duration. Experimental reduction of PMCA expression not only alters the dynamics of cellular Ca2+ handling but also has a myriad of downstream consequences on various aspects of cell function, indicating a broad role of these pumps. Age- and oxidation-related down-regulation of the PMCAs may play an important role in compromised neuronal function in the aging brain and its several-fold increased susceptibility to neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, and stroke. Therapeutic approaches that protect the PMCAs and stabilize [Ca2+]i homeostasis may be capable of slowing and/or preventing neuronal degeneration. The PMCAs are therefore emerging as a new class of drug targets for therapeutic interventions in various chronic degenerative disorders.
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234
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Dean WL. Role of platelet plasma membrane Ca 2+-ATPase in health and disease. World J Biol Chem 2010; 1:265-70. [PMID: 21537483 PMCID: PMC3083976 DOI: 10.4331/wjbc.v1.i9.265] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 08/24/2010] [Accepted: 08/31/2010] [Indexed: 02/05/2023] Open
Abstract
Platelets have essential roles in both health and disease. Normal platelet function is required for hemostasis. Inhibition of platelet function in disease or by pharmacological treatment results in bleeding disorders. On the other hand, hyperactive platelets lead to heart attack and stroke. Calcium is a major second messenger in platelet activation, and elevated intracellular calcium leads to hyperactive platelets. Elevated platelet calcium has been documented in hypertension and diabetes; both conditions increase the likelihood of heart attack and stroke. Thus, proper regulation of calcium metabolism in the platelet is extremely important. Plasma membrane Ca2+-ATPase (PMCA) is a major player in platelet calcium metabolism since it provides the only significant route for calcium efflux. In keeping with the important role of calcium in platelet function, PMCA is a highly regulated transporter. In human platelets, PMCA is activated by Ca2+/calmodulin, by cAMP-dependent phosphorylation and by calpain-dependent removal of the inhibitory peptide. It is inhibited by tyrosine phosphorylation and calpain-dependent proteolysis. In addition, the cellular location of PMCA is regulated by a PDZ-domain-dependent interaction with the cytoskeleton during platelet activation. Rapid regulation by phosphorylation results in changes in the rate of platelet activation, whereas calpain-dependent proteolysis and interaction with the cytoskeleton appears to regulate later events such as clot retraction. In hypertension and diabetes, PMCA expression is upregulated while activity is decreased, presumably due to tyrosine phosphorylation. Clearly, a more complete understanding of PMCA function in human platelets could result in the identification of new ways to control platelet function in disease states.
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235
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Pillich RT, Scarsella G, Risuleo G. Regeneration and DNA demethylation do not trigger PDX-1 expression in rat hepatocytes. World J Biol Chem 2010; 1:281-5. [PMID: 21537485 PMCID: PMC3083974 DOI: 10.4331/wjbc.v1.i9.281] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 06/22/2010] [Accepted: 06/29/2010] [Indexed: 02/05/2023] Open
Abstract
AIM: To explore the possibility that PDX-1 gene is reactivated as a consequence of molecular events that occur during liver regeneration.
METHODS: Rat hepatocytes were maintained in DMEM-F12, 10% fetal bovine serum (FBS), penicillin/streptomycin and geneticin when applicable. Rat insulinoma RIN 1046-38 cells were maintained in M-199-10% FBS and penicillin/streptomycin. The final concentration of glucose was 11.1 mmol/L. During regeneration, lateral and medial liver lobes of adult male Wistar rats were surgically removed, with up 70% loss of liver mass. In methylation experiments, 5-aza-deoxycytidine (5-aza-dC) was used. Primer3 software was used for polymerase chain reaction (PCR). Quantitative real time PCR (qRT-PCR) was performed using SYBR Green technology; primers were designed by Beacon Designer 6 software. Western blotting and SDS-PAGE were performed according to standard procedures. Antibodies were purchased from commercial suppliers.
RESULTS: We explored the possibility that liver regeneration could trigger PDX-1 expression, and hence insulin production. Twenty-four hours after surgical liver removal, regeneration was active as demonstrated by the increased proliferating cell nuclear antigen; however, all the other checked genes (involved in insulin gene expression): PC-1, Ngn3, NeuroD1, Btc, PDX-1 and Ins-1, were not related to the molecular events caused by this process. The only marker detected in regenerating liver was E47: a transcription factor of the the basic helix-loop-helix family known to be expressed ubiquitously in mammalian cells. In the rat pancreas, almost all of the tested genes were expressed as shown by RT-PCR, except for Ngn3, which was silenced 2 d after birth. Therefore, the molecular events in liver regeneration are not sufficient to promote PDX-1 expression. DNA methylation is a known mechanism to achieve stable repression of gene expression in mammals: Hxk 2 gene is silenced through this mechanism in normal hepatocytes. The administration of 5-aza-dC to cultured cells is in fact able to upregulate Hxk 2 mRNA. We investigated whether PDX-1 silencing in liver cells could be exerted through methylation of CpG islands in both the promoter and the gene coding regions. The results show that the drug increased the expression level of the Hxk 2 control gene but failed to rescue the expression of PDX-1, thus DNA demethylation is not sufficient to override repression of the PDX-1 gene.
CONCLUSION: During liver regeneration, PDX-1 gene is not reactivated. Demethylation does not de-repress PDX-1 gene expression. Therefore gene silencing is not achieved through this epigenetic mechanism.
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236
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Li Y, Yang KJ, Park J. Multiple implications of 3-phosphoinositide-dependent protein kinase 1 in human cancer. World J Biol Chem 2010; 1:239-47. [PMID: 21537480 PMCID: PMC3083972 DOI: 10.4331/wjbc.v1.i8.239] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 07/13/2010] [Accepted: 07/20/2010] [Indexed: 02/05/2023] Open
Abstract
3-phosphoinositide-dependent protein kinase-1 (PDK1) is a central mediator of cellular signaling between phosphoinositide-3 kinase and various intracellular serine/threonine kinases, including protein kinase B, p70 ribosomal S6 kinase, serum and glucocorticoid-inducible kinase, and protein kinase C. PDK1 activates members of the AGC family of protein kinases by phosphorylating serine/threonine residues in the activation loop. Here, we review the regulatory mechanisms of PDK1 and its roles in cancer. PDK1 is activated by autophosphorylation in the activation loop and other serine residues, as well as by phosphorylation of Tyr-9 and Tyr-373/376. Src appears to recognize PDK1 following tyrosine phosphorylation. The role of heat shock protein 90 in regulating PDK1 stability and PDK1-Src complex formation are also discussed. Furthermore, we summarize the subcellular distribution of PDK1. Finally, an important role for PDK1 in cancer chemotherapy is proposed. In conclusion, a better understanding of its molecular regulatory mechanisms in various signaling pathways will help to explain how PDK1 acts as an oncogenic kinase in various cancers, and will contribute to the development of novel cancer chemotherapies.
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237
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Roberts-Thomson SJ, Curry MC, Monteith GR. Plasma membrane calcium pumps and their emerging roles in cancer. World J Biol Chem 2010; 1:248-53. [PMID: 21537481 PMCID: PMC3083970 DOI: 10.4331/wjbc.v1.i8.248] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 06/25/2010] [Accepted: 07/02/2010] [Indexed: 02/05/2023] Open
Abstract
Alterations in calcium signaling and/or the expression of calcium pumps and channels are an increasingly recognized property of some cancer cells. Alterations in the expression of plasma membrane calcium ATPase (PMCA) isoforms have been reported in a variety of cancer types, including those of breast and colon, with some studies of cancer cell line differentiation identifying specific PMCA isoforms, which may be altered in some cancers. Some studies have also begun to assess levels of PMCA isoforms in clinical tumor samples and to address mechanisms of altered PMCA expression in cancers. Both increases and decreases in PMCA expression have been reported in different cancer types and in many cases these alterations are isoform specific. In this review, we provide an overview of studies investigating the expression of PMCA in cancer and discuss how both the overexpression and reduced expression of a PMCA isoform in a cancer cell could bestow a growth advantage, through augmenting responses to proliferative stimuli or reducing sensitivity to apoptosis.
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238
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Rahajeng J, Giridharan SSP, Cai B, Naslavsky N, Caplan S. Important relationships between Rab and MICAL proteins in endocytic trafficking. World J Biol Chem 2010; 1:254-64. [PMID: 21537482 PMCID: PMC3083971 DOI: 10.4331/wjbc.v1.i8.254] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 07/28/2010] [Accepted: 08/04/2010] [Indexed: 02/05/2023] Open
Abstract
The internalization of essential nutrients, lipids and receptors is a crucial process for all eukaryotic cells. Accordingly, endocytosis is highly conserved across cell types and species. Once internalized, small cargo-containing vesicles fuse with early endosomes (also known as sorting endosomes), where they undergo segregation to distinct membrane regions and are sorted and transported on through the endocytic pathway. Although the mechanisms that regulate this sorting are still poorly understood, some receptors are directed to late endosomes and lysosomes for degradation, whereas other receptors are recycled back to the plasma membrane; either directly or through recycling endosomes. The Rab family of small GTP-binding proteins plays crucial roles in regulating these trafficking pathways. Rabs cycle from inactive GDP-bound cytoplasmic proteins to active GTP-bound membrane-associated proteins, as a consequence of the activity of multiple specific GTPase-activating proteins (GAPs) and GTP exchange factors (GEFs). Once bound to GTP, Rabs interact with a multitude of effector proteins that carry out Rab-specific functions. Recent studies have shown that some of these effectors are also interaction partners for the C-terminal Eps15 homology (EHD) proteins, which are also intimately involved in endocytic regulation. A particularly interesting example of common Rab-EHD interaction partners is the MICAL-like protein, MICAL-L1. MICAL-L1 and its homolog, MICAL-L2, belong to the larger MICAL family of proteins, and both have been directly implicated in regulating endocytic recycling of cell surface receptors and junctional proteins, as well as controlling cytoskeletal rearrangement and neurite outgrowth. In this review, we summarize the functional roles of MICAL and Rab proteins, and focus on the significance of their interactions and the implications for endocytic transport.
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239
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Saerens D. Isolation and optimization of camelid single-domain antibodies: Dirk Saerens’ work on nanobodies. World J Biol Chem 2010; 1:235-8. [PMID: 21537479 PMCID: PMC3083966 DOI: 10.4331/wjbc.v1.i7.235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 07/01/2010] [Accepted: 07/08/2010] [Indexed: 02/05/2023] Open
Abstract
It is well established that all camelids have unique antibodies circulating in their blood. Unlike antibodies from all other species, these special antibodies are devoid of light chains, and are composed of a heavy chain homodimer. These so-called heavy-chain antibodies (HCAbs) are expressed after a V-D-J rearrangement and require dedicated constant gamma genes. An immune response is raised in these HCAbs following a classical immunization protocol. These HCAbs are easily purified from serum, and their antigen-binding fragment interacts with parts of the target that are less antigenic to conventional antibodies. The antigen binding site of the dromedary HCAb comprises one single domain, referred to as VHH or nanobody (Nb), therefore, a strategy was designed to clone the Nb repertoire of an immunized dromedary and to select the Nb with specificity for our target antigens. The monoclonal Nb is produced well in bacteria, is very stable and highly soluble, and it binds the antigen with high affinity and specificity. Currently, the recombinant Nb has been developed successfully for research purposes, as a probe in biosensors, to diagnose infections, or to treat diseases such as cancer or trypanosomiasis.
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240
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Mata AM, Sepulveda MR. Plasma membrane Ca 2+-ATPases in the nervous system during development and ageing. World J Biol Chem 2010; 1:229-34. [PMID: 21537478 PMCID: PMC3083968 DOI: 10.4331/wjbc.v1.i7.229] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Revised: 07/01/2010] [Accepted: 07/08/2010] [Indexed: 02/05/2023] Open
Abstract
Calcium signaling is used by neurons to control a variety of functions, including cellular differentiation, synaptic maturation, neurotransmitter release, intracellular signaling and cell death. This review focuses on one of the most important Ca2+ regulators in the cell, the plasma membrane Ca2+-ATPase (PMCA), which has a high affinity for Ca2+ and is widely expressed in brain. The ontogeny of PMCA isoforms, linked to specific requirements of Ca2+ during development of different brain areas, is addressed, as well as their function in the adult tissue. This is based on the high diversity of variants in the PMCA family in brain, which show particular kinetic differences possibly related to specific localizations and functions of the cell. Conversely, alterations in the activity of PMCAs could lead to changes in Ca2+ homeostasis and, consequently, to neural dysfunction. The involvement of PMCA isoforms in certain neuropathologies and in brain ageing is also discussed.
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241
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Itamochi H. Targeted therapies in epithelial ovarian cancer: Molecular mechanisms of action. World J Biol Chem 2010; 1:209-20. [PMID: 21537476 PMCID: PMC3083967 DOI: 10.4331/wjbc.v1.i7.209] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 07/08/2010] [Accepted: 07/15/2010] [Indexed: 02/05/2023] Open
Abstract
Ovarian cancer is the leading cause of death in women with gynecological cancer. Most patients are diagnosed at an advanced stage and have a poor prognosis. Currently, surgical tumor debulking, followed by platinum- and taxane-based chemotherapy is the standard treatment for advanced ovarian cancer. However, these patients are at great risk of recurrence and emerging drug resistance. Therefore, novel treatment strategies are required to improve outcomes for women with advanced ovarian cancer. A variety of molecular targeted agents, the majority of which are monoclonal antibodies and small-molecule protein-kinase inhibitors, have been explored in the management of ovarian cancer. The targets of these agents include angiogenesis, the human epidermal growth factor receptor family, ubiquitin-proteasome pathway, epigenetic modulators, poly(ADP-ribose) polymerase (PARP), and mammalian target of rapamycin (mTOR) signaling pathway, which are aberrant in tumor tissue. The antiangiogenic agent, bevacizumab, has been reported as the most effective targeted agent and should be included in the standard chemotherapeutic regimen for advanced ovarian cancer. PARP inhibitors, which are mainly used in breast and ovarian cancer susceptibility gene-mutated patients, and mTOR inhibitors are also attractive treatment strategies, either alone or combination with chemotherapy, for ovarian cancer. Understanding the tumor molecular biology and identification of predictive biomarkers are essential steps for selection of the best treatment strategies. This article reviews the molecular mechanisms of the most promising targeted agents that are under early phase clinical evaluation for ovarian cancer.
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242
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Bruce JI. Plasma membrane calcium pump regulation by metabolic stress. World J Biol Chem 2010; 1:221-8. [PMID: 21537477 PMCID: PMC3083969 DOI: 10.4331/wjbc.v1.i7.221] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2010] [Revised: 06/30/2010] [Accepted: 07/07/2010] [Indexed: 02/05/2023] Open
Abstract
The plasma membrane Ca2+-ATPase (PMCA) is an ATP-driven pump that is critical for the maintenance of low resting [Ca2+]i in all eukaryotic cells. Metabolic stress, either due to inhibition of mitochondrial or glycolytic metabolism, has the capacity to cause ATP depletion and thus inhibit PMCA activity. This has potentially fatal consequences, particularly for non-excitable cells in which the PMCA is the major Ca2+ efflux pathway. This is because inhibition of the PMCA inevitably leads to cytosolic Ca2+ overload and the consequent cell death. However, the relationship between metabolic stress, ATP depletion and inhibition of the PMCA is not as simple as one would have originally predicted. There is increasing evidence that metabolic stress can lead to the inhibition of PMCA activity independent of ATP or prior to substantial ATP depletion. In particular, there is evidence that the PMCA has its own glycolytic ATP supply that can fuel the PMCA in the face of impaired mitochondrial function. Moreover, membrane phospholipids, mitochondrial membrane potential, caspase/calpain cleavage and oxidative stress have all been implicated in metabolic stress-induced inhibition of the PMCA. The major focus of this review is to challenge the conventional view of ATP-dependent regulation of the PMCA and bring together some of the alternative or additional mechanisms by which metabolic stress impairs PMCA activity resulting in cytosolic Ca2+ overload and cytotoxicity.
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Holton ML, Wang W, Emerson M, Neyses L, Armesilla AL. Plasma membrane calcium ATPase proteins as novel regulators of signal transduction pathways. World J Biol Chem 2010; 1:201-8. [PMID: 21537369 PMCID: PMC3083965 DOI: 10.4331/wjbc.v1.i6.201] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 06/22/2010] [Accepted: 06/24/2010] [Indexed: 02/05/2023] Open
Abstract
Emerging evidence suggests that plasma membrane calcium ATPases (PMCAs) play a key role as regulators of calcium-triggered signal transduction pathways via interaction with partner proteins. PMCAs regulate these pathways by targeting specific proteins to cellular sub-domains where the levels of intracellular free calcium are kept low by the calcium ejection properties of PMCAs. According to this model, PMCAs have been shown to interact functionally with the calcium-sensitive proteins neuronal nitric oxide synthase, calmodulin-dependent serine protein kinase, calcineurin and endothelial nitric oxidase synthase. Transgenic animals with altered expression of PMCAs are being used to evaluate the physiological significance of these interactions. To date, PMCA interactions with calcium-dependent partner proteins have been demonstrated to play a crucial role in the pathophysiology of the cardiovascular system via regulation of the nitric oxide and calcineurin/nuclear factor of activated T cells pathways. This new evidence suggests that PMCAs play a more sophisticated role than the mere ejection of calcium from the cells, by acting as modulators of signaling transduction pathways.
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Labbé S. Simon Labbé's work on iron and copper homeostasis. World J Biol Chem 2010; 1:196-200. [PMID: 21541004 PMCID: PMC3083951 DOI: 10.4331/wjbc.v1.i5.196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2010] [Revised: 05/18/2010] [Accepted: 05/25/2010] [Indexed: 02/05/2023] Open
Abstract
Iron and copper have a wealth of functions in biological systems, which makes them essential micronutrients for all living organisms. Defects in iron and copper homeostasis are directly responsible for diseases, and have been linked to impaired development, metabolic syndromes and fungal virulence. Consequently, it is crucial to gain a comprehensive understanding of the molecular bases of iron- and copper-dependent proteins in living systems. Simon Labbé maintains parallel programs on iron and copper homeostasis using the fission yeast Schizosaccharomyces pombe (Schiz. pombe) as a model system. The study of fission yeast transition-metal metabolism has been successful, not only in discerning the genes and pathways functioning in Schiz. pombe, but also the genes and pathways that are active in mammalian systems and for other fungi.
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Fakira AK, Elkabes S. Role of plasma membrane calcium ATPase 2 in spinal cord pathology. World J Biol Chem 2010; 1:103-8. [PMID: 21540996 PMCID: PMC3083954 DOI: 10.4331/wjbc.v1.i5.103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 05/11/2010] [Accepted: 05/18/2010] [Indexed: 02/05/2023] Open
Abstract
A number of studies have indicated that plasma membrane calcium ATPases (PMCAs) are expressed in the brain and spinal cord and could play important roles not only in the maintenance of cellular calcium homeostasis but also in the survival and function of central nervous system cells under pathological conditions. The different regional and cellular distributions of the various PMCA isoforms and splice variants in the nervous system and the diverse phenotypes of PMCA knockout mice support the notion that each isoform might play a distinct role. Especially in the spinal cord, the survival of neurons and, in particular, motor neurons could be dependent on PMCA2. This is indicated by the knockdown of PMCA2 in pure spinal cord neuronal cultures that leads to cell death via a decrease in collapsing response mediator protein 1 levels. Moreover, the progressive decline in the number of motor neurons in PMCA2-null mice and heterozygous mice further supports this notion. Therefore, the reported reduction in PMCA2 mRNA and protein levels in the inflamed spinal cord of mice affected by experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, and after spinal cord contusion injury, suggests that changes in PMCA2 expression could be a cause of neuronal pathology and death during inflammation and injury. Glutamate excitotoxicity mediated via kainate receptors has been implicated in the neuropathology of both EAE and spinal cord injury, and has been identified as a trigger that reduces PMCA2 levels in pure spinal cord neuronal cultures through degradation of the pump by calpain without affecting PMCA2 transcript levels. It remains to be determined which other stimuli modulate PMCA2 mRNA expression in the aforementioned pathological conditions of the spinal cord.
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Wang JH, Valanne S, Rämet M. Drosophila as a model for antiviral immunity. World J Biol Chem 2010; 1:151-9. [PMID: 21541000 PMCID: PMC3083956 DOI: 10.4331/wjbc.v1.i5.151] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 05/04/2010] [Accepted: 05/17/2010] [Indexed: 02/05/2023] Open
Abstract
The fruit fly Drosophila melanogaster has been successfully used to study numerous biological processes including immune response. Flies are naturally infected with more than twenty RNA viruses making it a valid model organism to study host-pathogen interactions during viral infections. The Drosophila antiviral immunity includes RNA interference, activation of the JAK/STAT and other signaling cascades and other mechanisms such as autophagy and interactions with other microorganisms. Here we review Drosophila as an immunological research model as well as recent advances in the field of Drosophila antiviral immunity.
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Witzany G. Uniform categorization of biocommunication in bacteria, fungi and plants. World J Biol Chem 2010; 1:160-80. [PMID: 21541001 PMCID: PMC3083953 DOI: 10.4331/wjbc.v1.i5.160] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 05/11/2010] [Accepted: 05/18/2010] [Indexed: 02/05/2023] Open
Abstract
This article describes a coherent biocommunication categorization for the kingdoms of bacteria, fungi and plants. The investigation further shows that, besides biotic sign use in trans-, inter- and intraorganismic communication processes, a common trait is interpretation of abiotic influences as indicators to generate an appropriate adaptive behaviour. Far from being mechanistic interactions, communication processes within organisms and between organisms are sign-mediated interactions. Sign-mediated interactions are the precondition for every cooperation and coordination between at least two biological agents such as cells, tissues, organs and organisms. Signs of biocommunicative processes are chemical molecules in most cases. The signs that are used in a great variety of signaling processes follow syntactic (combinatorial), pragmatic (context-dependent) and semantic (content-specific) rules. These three levels of semiotic rules are helpful tools to investigate communication processes throughout all organismic kingdoms. It is not the aim to present the latest empirical data concerning communication in these three kingdoms but to present a unifying perspective that is able to interconnect transdisciplinary research on bacteria, fungi and plants.
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Numakawa T, Yokomaku D, Richards M, Hori H, Adachi N, Kunugi H. Functional interactions between steroid hormones and neurotrophin BDNF. World J Biol Chem 2010; 1:133-43. [PMID: 21540998 PMCID: PMC3083963 DOI: 10.4331/wjbc.v1.i5.133] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 05/20/2010] [Accepted: 05/24/2010] [Indexed: 02/05/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF), a critical neurotrophin, regulates many neuronal aspects including cell differentiation, cell survival, neurotransmission, and synaptic plasticity in the central nervous system (CNS). Though BDNF has two types of receptors, high affinity tropomyosin-related kinase (Trk)B and low affinity p75 receptors, BDNF positively exerts its biological effects on neurons via activation of TrkB and of resultant intracellular signaling cascades including mitogen-activated protein kinase/extracellular signal-regulated protein kinase, phospholipase Cγ, and phosphoinositide 3-kinase pathways. Notably, it is possible that alteration in the expression and/or function of BDNF in the CNS is involved in the pathophysiology of various brain diseases such as stroke, Parkinson’s disease, Alzheimer’s disease, and mental disorders. On the other hand, glucocorticoids, stress-induced steroid hormones, also putatively contribute to the pathophysiology of depression. Interestingly, in addition to the reduction in BDNF levels due to increased glucocorticoid exposure, current reports demonstrate possible interactions between glucocorticoids and BDNF-mediated neuronal functions. Other steroid hormones, such as estrogen, are involved in not only sexual differentiation in the brain, but also numerous neuronal events including cell survival and synaptic plasticity. Furthermore, it is well known that estrogen plays a role in the pathophysiology of Parkinson’s disease, Alzheimer’s disease, and mental illness, while serving to regulate BDNF expression and/or function. Here, we present a broad overview of the current knowledge concerning the association between BDNF expression/function and steroid hormones (glucocorticoids and estrogen).
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Maeda N, Uede T. Swine-origin influenza-virus-induced acute lung injury: Novel or classical pathogenesis? World J Biol Chem 2010; 1:85-94. [PMID: 21540994 PMCID: PMC3083955 DOI: 10.4331/wjbc.v1.i5.85] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 05/19/2010] [Accepted: 05/21/2010] [Indexed: 02/05/2023] Open
Abstract
Influenza viruses are common respiratory pathogens in humans and can cause serious infection that leads to the development of pneumonia. Due to their host-range diversity, genetic and antigenic diversity, and potential to reassort genetically in vivo, influenza A viruses are continual sources of novel influenza strains that lead to the emergence of periodic epidemics and outbreaks in humans. Thus, newly emerging viral diseases are always major threats to public health. In March 2009, a novel influenza virus suddenly emerged and caused a worldwide pandemic. The novel pandemic influenza virus was genetically and antigenically distinct from previous seasonal human influenza A/H1N1 viruses; it was identified to have originated from pigs, and further genetic analysis revealed it as a subtype of A/H1N1, thus later called a swine-origin influenza virus A/H1N1. Since the novel virus emerged, epidemiological surveys and research on experimental animal models have been conducted, and characteristics of the novel influenza virus have been determined but the exact mechanisms of pulmonary pathogenesis remain to be elucidated. In this editorial, we summarize and discuss the recent pandemic caused by the novel swine-origin influenza virus A/H1N1 with a focus on the mechanism of pathogenesis to obtain an insight into potential therapeutic strategies.
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Wu F, Fan S, Martiniuk F, Pincus S, Müller S, Kohler H, Tchou-Wong KM. Protective effects of anti-ricin A-chain antibodies delivered intracellularly against ricin-induced cytotoxicity. World J Biol Chem 2010; 1:188-95. [PMID: 21541003 PMCID: PMC3083952 DOI: 10.4331/wjbc.v1.i5.188] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 05/15/2010] [Accepted: 05/22/2010] [Indexed: 02/05/2023] Open
Abstract
AIM: To evaluate the ability of anti-ricin A-chain antibodies, delivered intracellularly, to protect against ricin-induced cytotoxicity in RAW264.7 cells.
METHODS: Anti-deglycosylated ricin A-chain antibody and RAC18 anti-ricin A-chain monoclonal antibody were delivered intracellularly by encapsulating in liposomes or via conjugation with the cell-penetrating MTS-transport peptide. RAW264.7 cells were incubated with these antibodies either before or after ricin exposure. The changes in cytotoxicity were estimated by MTT assay. Co-localization of internalized antibody and ricin was evaluated by fluorescence microscopy.
RESULTS: Internalized antibodies significantly increased cell viability either before or after ricin exposure compared to the unconjugated antibodies. Fluorescence microscopy confirmed the co-localization of internalized antibodies and ricin inside the cells.
CONCLUSION: Intracellular delivery of antibodies to neutralize the ricin toxin after cellular uptake supports the potential use of cell-permeable antibodies for post-exposure treatment of ricin intoxication.
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