Therapeutic effect of autologous compact bone-derived mesenchymal stem cell transplantation on prion disease.

Prion diseases are fatal neurodegenerative disorders of humans and animals and no effective treatments are currently available. Allogenic transplantation of immortalized human mesenchymal stem cells (MSCs) can prolong the survival of mice infected with prions. However, autologous transplantation is an appropriate model for evaluating the effects of MSCs on prion diseases. Therefore, we isolated and purified MSCs from the femur and tibia of mice as compact bone-derived MSCs (CB-MSCs). Flow cytometric analysis showed that CB-MSCs were negative for myeloid stem cell-derived cell markers CD11b and CD45, but positive for molecules such as Sca-1, CD105 and CD90.2, which are reported to be expressed on MSCs. The ability of CB-MSCs to migrate to brain extracts from prion-infected mice was confirmed by an in vitro migration assay. Intra-hippocampus transplantation of CB-MSCs at 120 days post-inoculation marginally but significantly prolonged the survival of mice infected with the Chandler prion strain. The transplantation of CB-MSCs did not influence the accumulation of disease-specific prion protein. However, the CB-MSC transplantation enhanced microglial activation, which appeared to be polarized to the M2-type activation state. These results suggest that autologous MSC transplantation is a possible treatment for prion diseases, while the modification of microglial activation may be a therapeutic target for neurodegenerative diseases.

Tenascin-C-derived peptide TNIIIA2 highly enhances cell survival and platelet-derived growth factor (PDGF)-dependent cell proliferation through potentiated and sustained activation of integrin α5ß1.

Tenascin-C is an adhesion modulatory matrix protein that is highly expressed in tumors; however, its biochemical activity involved in tumorigenesis is not fully understood. On the other hand, increasing evidence indicates the importance of integrin α5ß1 in cancer development. We previously demonstrated that tenascin-C harbors a functional site that can be released as a proadhesive peptide such as TNIIIA2. Peptide TNIIIA2 is capable of inducing activation of ß1-integrins including α5ß1 via syndecan-4. In this study the proadhesive effect of TNIIIA2 was characterized by potentiated and sustained activation of integrin α5ß1. Based on this effect, TNIIIA2 rendered nontransformed fibroblasts (NIH3T3) resistant to serum deprivation-elicited anoikis through activation of the Akt/Bcl-2 pathway. Moreover, TNIIIA2 hyperstimulated PDGF-dependent proliferation of NIH3T3 by activating integrin α5ß1. Tenascin-C, a parental protein of TNIIIA2, also stimulated PDGF-dependent proliferation, which was blocked by a matrix metalloproteinase-2/9 inhibitor and an anti-TNIIIA2 function-blocking antibody, suggesting proteolytic exposure of the proadhesive effect of TNIIIA2. Mechanistic analyses revealed that TNIIIA2 induced a lateral association of PDGF receptor ß with the molecular complex of activated integrin α5ß1 and syndecan-4 in the membrane microdomains enriched with cholesterol/caveolin-1, resulting in prolonged activation of PDGF receptor ß and the subsequent Ras/mitogen-activated protein kinase pathway in a PDGF-dependent manner. Of note, TNIIIA2 induced continuous proliferation in NIH3T3 in an integrin α5ß1-dependent manner even after they formed a confluent monolayer. Thus, it was proposed that tenascin-C might be involved in deregulated cell growth through potentiated and sustained activation of integrin α5ß1 after exposure of the proadhesive effect of TNIIIA2.

Development of potent antagonists for formyl peptide receptor 1 based on Boc-Phe-D-Leu-Phe-D-Leu-Phe-OH.

While stimulation of formyl peptide receptors (FPRs) on the surface of human neutrophils induces several immune responses, under conditions of continuous activation of the receptor by agonists such as formyl-Met-Leu-Phe-OH (fMLP), neutrophil-dependent tissue damage ensues. Thus, FPR antagonists could be anticipated as drugs for FPR-related disease. In this study, Boc-Phe-D-Leu-Phe-D-Leu-Phe-OH (Boc-FlFlF), one of several FPR subtype selective antagonists, was chosen and the positions at the Phe residues were optimized. We found that substitution with unnatural amino acids resulted in an improvement of two orders of magnitude. The most potent antagonist indicated FPR subtype selectivity at 1 µM. In addition to finding a potent antagonist, the structure-activity trends observed in this study should be valuable in designing a new type of FPR subtype selective antagonist.

GTP-binding protein-like domain of AGAP1 is protein binding site that allosterically regulates ArfGAP protein catalytic activity.

AGAPs are a subtype of Arf GTPase-activating proteins (GAPs) with 11 members in humans. In addition to the Arf GAP domain, the proteins contain a G-protein-like domain (GLD) with homology to Ras superfamily proteins and a PH domain. AGAPs bind to clathrin adaptors, function in post Golgi membrane traffic, and have been implicated in glioblastoma. The regulation of AGAPs is largely unexplored. Other enzymes containing GTP binding domains are regulated by nucleotide binding. However, nucleotide binding to AGAPs has not been detected. Here, we found that neither nucleotides nor deleting the GLD of AGAP1 affected catalysis, which led us to hypothesize that the GLD is a protein binding site that regulates GAP activity. Two-hybrid screens identified RhoA, Rac1, and Cdc42 as potential binding partners. Coimmunoprecipitation confirmed that AGAP1 and AGAP2 can bind to RhoA. Binding was mediated by the C terminus of RhoA and was independent of nucleotide. RhoA and the C-terminal peptide from RhoA increased GAP activity specifically for the substrate Arf1. In contrast, a C-terminal peptide from Cdc42 neither bound nor activated AGAP1. Based on these results, we propose that AGAPs are allosterically regulated through protein binding to the GLD domain.

A formyl peptide substituted with a conformationally constrained phenylalanine residue evokes a selective immune response in human neutrophils.

Formyl-Met-Leu-Phe-OH (fMLP) binds to formyl peptide receptors, FPR1 and FPR2, and evokes migration and superoxide anion production in human neutrophils. To obtain a more effective and selective ligand, fMLP analogs in which the Phe residue was substituted with four isomers of cyclopropanephenylalanine were synthesized. While Z-isomer peptides induced both migration and superoxide anion production, E-isomer peptides elicited only chemotaxis. Homologous receptor desensitization experiments revealed that E-isomer peptides bound to FPR2. Although a selective agonist of chemotaxis also binds to FPR2 without increasing intracellular calcium concentration, E-isomer peptide elevated the concentration to the same level as fMLP. Understanding of mechanisms responsible for the selectivity of the reported selective agonists and ∇Phe-substituted analogs should prove useful for revealing the relationship between receptor-ligand interactions and biological responses of human neutrophils.

Management of bronchopulmonary dysplasia in Japan: A nationwide survey.

BACKGROUND: The incidence of bronchopulmonary dysplasia (BPD) and respiratory management practices for extremely low birth weight infants (ELBWIs) widely vary among institutions and countries. AIMS: To clarify the variation and characteristics of the current practices of Japanese neonatologists managing patients with BPD. STUDY DESIGN: Questionnaire-based survey. PARTICIPANTS: Level II and III perinatal centers certified by the Japan Society of Perinatal and Neonatal Medicine. OUTCOME MEASURES: Policies of the neonatal intensive care units (NICUs) regarding respiratory care and medications for BPD prevention and treatment. RESULTS: A total of 76 % of facilities (207/274) responded to our survey. The response rates of level III and II facilities were 91 % (102/112) and 35 % (105/296), respectively. INtubation-SURfactant-Extubation and Less Invasive Surfactant Administration methods were performed in 23 % (47/206) and 1 % (3/206) of facilities, respectively. For the prophylactic purpose, systemic and inhaled steroids were administered "frequently" or "occasionally" in 14 % (28/205) and 42 % (86/204) of NICUs, respectively. For the therapeutic purpose, systemic and inhaled steroids were administered "frequently" or "occasionally" in 84 % (171/204) and 29 % (59/204) of NICUs, respectively. Approximately half of the NICUs (99/202) used volume-targeted ventilation (VTV) "frequently" or "occasionally" in progressing BPD. High-frequency oscillation ventilation (HFOV) was used for progressing BPD "frequently" and "occasionally" in 89 % (180/202) of the facilities. CONCLUSIONS: Our study provided an overview and characteristics of BPD management in Japan in recent years. Noninvasive approaches with surfactant administration remain not widely used in Japan. HFOV is a widely accepted management for progressing BPD.

Small-molecule inactivation of HIV-1 NCp7 by repetitive intracellular acyl transfer.

The zinc fingers of the HIV-1 nucleocapsid protein, NCp7, are prime targets for antiretroviral therapeutics. Here we show that S-acyl-2-mercaptobenzamide thioester (SAMT) chemotypes inhibit HIV by modifying the NCp7 region of Gag in infected cells, thereby blocking Gag processing and reducing infectivity. The thiol produced by SAMT reaction with NCp7 is acetylated by cellular enzymes to regenerate active SAMTs via a recycling mechanism unique among small-molecule inhibitors of HIV.

The cell adhesion and proliferation activities of a peptide derived from human tenascin-C are dependent on two Ile residues.

A tenascin-C derived peptide (TNIIIA2 peptide, 1) stimulated ß1 integrin-mediated cell adhesion via binding to syndecan-4. Ala-substituted peptides were synthesized to understand the structure-activity relationship. Peptides in which basic amino acids were substituted showed reduced cell adhesion activity, but their proliferation activities were similar to or higher than those mediated by peptide 1. In contrast, peptides in which the Ile residues of peptide 1 were replaced were inactive, indicating that the Ile residues are critical for the peptide's activity. CD analysis suggested that the Ile residues are necessary for the formation of a specific conformation required for binding to syndecan-4.

First Pediatric Case of Clinically-Diagnosed Penicillin G-Induced Hemorrhagic Cystitis.

Hemorrhagic cystitis is a diffuse inflammatory disease of the urinary bladder associated with macrohematuria. Several cases of hemorrhagic cystitis caused by penicillin G have been reported in adults but not children. Here we describe the first pediatric case of clinically-diagnosed penicillin G-induced hemorrhagic cystitis. The patient was a 9-year-old boy with a ventricular septal defect, chromosomal abnormalities, and infective endocarditis caused by Abiotrophia defectiva. After approximately four weeks of penicillin G administration, he had a culture-negative major hemorrhage with a clot. The hematuria resolved one week after penicillin G discontinuation, and a drug lymphocyte stimulation test for penicillin G was positive. In conclusion, penicillin G can also induce hemorrhagic cystitis in children. When large doses of penicillin G are used for long periods in adults or children, the patient should be monitored for hemorrhagic cystitis.

Optimization of a cyclic peptide inhibitor of Ser/Thr phosphatase PPM1D (Wip1).

PPM1D (PP2Cδ or Wip1) was identified as a wild-type p53-induced Ser/Thr phosphatase that accumulates after DNA damage and classified into the PP2C family. It dephosphorylates and inactivates several proteins critical for cellular stress responses, including p38 MAPK, p53, and ATM. Furthermore, PPM1D is amplified and/or overexpressed in a number of human cancers. Thus, inhibition of its activity could constitute an important new strategy for therapeutic intervention to halt the progression of several different cancers. Previously, we reported the development of a cyclic thioether peptide with low micromolar inhibitory activity toward PPM1D. Here, we describe important improvements in the inhibitory activity of this class of cyclic peptides and also present a binding model based upon the results. We found that specific interaction of an aromatic ring at the X1 position and negative charge at the X5 and X6 positions significantly increased the inhibitory activity of the cyclic peptide, with the optimized molecule having a K(i) of 110 nM. To the best of our knowledge, this represents the highest inhibitory activity reported for an inhibitor of PPM1D. We further developed an inhibitor selective for PPM1D over PPM1A with a K(i) of 2.9 µM. Optimization of the cyclic peptide and mutagenesis experiments suggest that a highly basic loop unique to PPM1D is related to substrate specificity. We propose a new model for the catalytic site of PPM1D and inhibition by the cyclic peptides that will be useful both for the subsequent design of PPM1D inhibitors and for identification of new substrates.

The MBT repeats of L3MBTL1 link SET8-mediated p53 methylation at lysine 382 to target gene repression.

The p53 tumor suppressor protein is regulated by multiple post-translational modifications, including lysine methylation. We previously found that monomethylation of p53 at lysine 382 (p53K382me1) by the protein lysine methyltransferase (PKMT) SET8/PR-Set7 represses p53 transactivation of target genes. However, the molecular mechanism linking p53K382 monomethylation to repression is not known. Here we show in biochemical and crystallographic studies the preferential recognition of p53K382me1 by the triple malignant brain tumor (MBT) repeats of the chromatin compaction factor L3MBTL1. We demonstrate that SET8-mediated methylation of p53 at Lys-382 promotes the interaction between L3MBTL1 and p53 in cells, and the chromatin occupancy of L3MBTL1 at p53 target promoters. In the absence of DNA damage, L3MBTL1 interacts with p53K382me1 and p53-target genes are repressed, whereas depletion of L3MBTL1 results in a p53-dependent increase in p21 and PUMA transcript levels. Activation of p53 by DNA damage is coupled to a decrease in p53K382me1 levels, abrogation of the L3MBTL1-p53 interaction, and disassociation of L3MBTL1 from p53-target promoters. Together, we identify L3MBTL1 as the second known methyl-p53 effector protein, and provide a molecular explanation for the mechanism by which p53K382me1 is transduced to regulate p53 activity.

Structural basis for p300 Taz2-p53 TAD1 binding and modulation by phosphorylation.

Coactivators CREB-binding protein and p300 play important roles in mediating the transcriptional activity of p53. Until now, however, no detailed structural information has been available on how any of the domains of p300 interact with p53. Here, we report the NMR structure of the complex of the Taz2 (C/H3) domain of p300 and the N-terminal transactivation domain of p53. In the complex, p53 forms a short alpha helix and interacts with the Taz2 domain through an extended surface. Mutational analyses demonstrate the importance of hydrophobic residues for complex stabilization. Additionally, they suggest that the increased affinity of Taz2 for p53(1-39) phosphorylated at Thr(18) is due in part to electrostatic interactions of the phosphate with neighboring arginine residues in Taz2. Thermodynamic experiments revealed the importance of hydrophobic interactions in the complex of Taz2 with p53 phosphorylated at Ser(15) and Thr(18).

Human immunodeficiency virus type 1 nucleocapsid inhibitors impede trans infection in cellular and explant models and protect nonhuman primates from infection.

Here, we report that the S-acyl-2-mercaptobenzamide thioester (SAMT) class of human immunodeficiency virus type 1 (HIV-1) nucleocapsid protein (NCp7) inhibitors was able to prevent transmission of HIV-1 from infected cells, including primary cells. Furthermore, when SAMTs were introduced during an HIV-1 challenge of cervical explant tissue, inhibition of dissemination of infectious virus by cells emigrating from the tissue explants was observed. Preliminary studies using a rhesus macaque vaginal challenge model with mixed R5 and X4 simian-human immunodeficiency virus infection found that five of six monkeys were completely protected, with the remaining animal being partially protected, infected only by the R5 virus. These data suggest that SAMTs may be promising new drug candidates for further development in anti-HIV-1 topical microbicide applications.

Pyothorax-associated lymphoma diagnosed by preoperative pleural effusion aspiration cytology: a case report.

BACKGROUND: Pyothorax-associated lymphoma (PAL) is a comparatively rare tumor, and it is difficult to definitively diagnose it preoperatively, especially in patients with only pleural thickening without mass formation. Pleural effusion aspiration cytology is a useful and easy diagnostic method for a large number of chest diseases. However, the cytologic findings of PAL have been rarely described. Here we report on the cytologic findings in a patient with PAL, manifested by pleural thickening without mass formation, and which was diagnosed preoperatively by pleural effusion aspiration cytology. CASE: A 64-year-old man was admitted to our hospital because of pleural thickening involving an empyema sac located in the left thorax and rapidly increasing pleural effusion. He had a 30-year history of chronic empyema and a 10-year history of diabetes mellitus. Left pleural effusion aspiration cytology showed malignant lymphoma. The patient was admitted to our hospital for PAL treatment. Because of poor respiratory function, he only underwent decortication with complete resection of the thickening pleural peel. However, he was well, without recurrence, 5 years after the operation. The histologic examination revealed that lymphoma cells were located only in the thickening pleural peel. CONCLUSION: This is a very rare case of PAL diagnosed by preoperative aspiration cytology for an increasing pleural effusion. This report demonstrates that pleural effusion aspiration cytology can be valuable for the diagnosis of PAL.

Two distinct motifs within the p53 transactivation domain bind to the Taz2 domain of p300 and are differentially affected by phosphorylation.

The tumor suppressor p53 functions as a transcriptional activator for many genes, including several key genes involved in cell cycle arrest and apoptosis. Following DNA damage-induced stress, p53 undergoes extensive posttranslational modification, resulting in increased stability and activity. Two critical cofactors for p53-mediated transactivation are the histone acetyltransferase paralogues CREB-binding protein (CBP) and p300. The N-terminal transactivation domain of p53 interacts with several domains of CBP/p300, including the Taz2 domain. Here, we report the effects of specific p53 phosphorylations on its interaction with the Taz2 domain of p300. Using a competitive fluorescence anisotropy assay, we determined that monophosphorylation of p53 at Ser(15) or Thr(18) increased the affinity of p53(1-39) for Taz2, and diphosphorylations at Ser(15) and Ser(37) or Thr(18) and Ser(20) further increased the affinity. In addition, we identified a second binding site for Taz2 within p53 residues 35-59. This second site bound Taz2 with a similar affinity as the first site, but the binding was unaffected by phosphorylation. Thus, p53 posttranslational modification modulates only one of the two binding sites for p300 Taz2. Further investigation of Taz2 binding to p53(1-39) or p53(35-59) by isothermal titration calorimetry indicated that upon complex formation, the change in heat capacity at constant pressure, DeltaC(p), was negative for both sites, suggesting the importance of hydrophobic interactions. However, the more negative value of DeltaC(p) for Taz2 binding to the first (-330 cal/(mol.K)) compared to the second site (-234 cal/(mol.K)) suggests that the importance of nonpolar and polar interactions differs between the two sites.

N-acylpolyamine inhibitors of HDM2 and HDMX binding to p53.

Selective inhibition of protein-protein interactions important for cellular processes could lead to the development of new therapies against disease. In the area of cancer, overexpression of the proteins human double minute 2 (HDM2) and its homolog HDMX has been linked to tumor aggressiveness. Both HDM2 and HDMX bind to p53 and prevent cell cycle arrest or apoptosis in damaged cells. Developing a strategy to simultaneously prevent the binding of both HDM2 and HDMX to p53 is an essential feature of inhibitors to restore p53 activity in a number of different cancers. Inhibition of protein-protein interactions with synthetic molecules is an emerging area of research that requires new inhibitors tailored to mimic the types of interfaces between proteins. Our strategy to create inhibitors of protein-protein interactions is to develop a non-natural scaffold that may be used as a starting point to identify important molecular components necessary for inhibition. In this study, we report an N-acylpolyamine (NAPA) scaffold that supports numerous sidechains in a compact atomic arrangement. NAPAs were constructed by a series of reductive aminations between amino acid derivatives followed by acylation at the resulting secondary amine. An optimized NAPA was able to equally inhibit the association of both HDM2 and HDMX with p53. Our results demonstrate some of the challenges associated with targeting multiple protein-protein interactions involved in overlapping cellular processes.

Superoxide production in human neutrophils is enhanced by treatment with transmembrane peptides derived from human formyl peptide receptor.

Formyl peptide receptor (FPR) mediates a number of important host defense functions. Although studies have been performed on the ligand binding site of FPR, FPR dynamic behavior such as receptor dimerization on the cell surface remains unknown. Recently, peptides derived from the transmembrane (TM) domains of GPCRs were shown to disrupt dimer formation by receptors and to result in specific regulation of receptor function. To reveal the function of FPR TM domains, hFPRTM peptides derived from FPR were synthesized, and their biological activities were evaluated with human neutrophils. Synthetic peptides did not exhibit agonistic or antagonistic activity toward superoxide anion production. However, Neutrophils treated with hFPRTM4 produced 4-fold superoxide anion compared with untreated cells when stimulated with FPR agonist fMLP. Short peptide fragments derived from the fourth TM region of FPR did not enhance superoxide anion production, which suggests that hFPRTM4 did not behave as a ligand. CD and fluorescence spectra suggested that hFPRTM peptides were inserted into the membrane. The addition of hFPRTM4 increased the intracellular calcium concentration, which meant the peptide activated some membrane protein on the cell surface. The present study suggests that the fourth TM domain of FPR has a function related to a priming effect.

Targeting cancer stem cells with p53 modulators.

Cancer stem cells (CSC) typically over-express aldehyde dehydrogenase (ALDH). Thus, ALDHbright tumor cells represent targets for developing novel cancer prevention/treatment interventions. Loss of p53 function is a common genetic event during cancer development wherein small molecular weight compounds (SMWC) that restore p53 function and reverse tumor growth have been identified. Here, we focused on two widely studied p53 SMWC, CP-31398 and PRIMA-1, to target ALDHbright CSC in human breast, endometrial and pancreas carcinoma cell lines expressing mutant or wild type (WT) p53. CP-31398 and PRIMA-1 significantly reduced CSC content and sphere formation by these cell lines in vitro. In addition, these agents were more effective in vitro against CSC compared to cisplatin and gemcitabine, two often-used chemotherapeutic agents. We also tested a combinatorial treatment in methylcholantrene (MCA)-treated mice consisting of p53 SMWC and p53-based vaccines. Yet using survival end-point analysis, no increased efficacy in the presence of either p53 SMWC alone or with vaccine compared to vaccine alone was observed. These results may be due, in part, to the presence of immune cells, such as activated lymphocytes expressing WT p53 at levels comparable to some tumor cells, wherein further increase of p53 expression by p53 SMWC may alter survival of these immune cells and negatively impact an effective immune response. Continuous exposure of mice to MCA may have also interfered with the action of these p53 SMWC, including potential direct interaction with MCA. Nonetheless, the effect of p53 SMWC on CSC and cancer treatment remains of great interest.

Coadministration of the FNIII14 Peptide Synergistically Augments the Anti-Cancer Activity of Chemotherapeutic Drugs by Activating Pro-Apoptotic Bim.

The acquisition of drug resistance mediated by the interaction of tumor cells with the extracellular matrix (ECM), commonly referred to as cell adhesion-mediated drug resistance (CAM-DR), has been observed not only in hematopoietic tumor cells but also in solid tumor cells. We have previously demonstrated that a 22-mer peptide derived from fibronectin, FNIII14, can inhibit cell adhesion through the inactivation of ß1 integrin; when coadministered with cytarabine, FNIII14 completely eradicates acute myelogenous leukemia by suppressing CAM-DR. In this study, we show that our FNIII14 peptide also enhances chemotherapy efficacy in solid tumors. Coadministration of FNIII14 synergistically enhances the cytotoxicity of doxorubicin and aclarubicin in mammary tumor and melanoma cells, respectively. The solid tumor cell chemosensitization induced by FNIII14 is dependent upon the upregulation and activation of the pro-apoptotic protein, Bim. Furthermore, the metastasis of tumor cells derived from ventrally transplanted mammary tumor grafts is suppressed by the coadministration of FNIII14 and doxorubicin. These results suggest that the coadministration of our FNIII14 peptide with chemotherapy could achieve efficient solid tumor eradication by increasing chemosensitivity and decreasing metastasis. The major causes of tumor recurrence are the existence of chemotherapy-resistant primary tumor cells and the establishment of secondary metastatic lesions. As such, coadministering FNIII14 with anti-cancer drugs could provide a promising new approach to improve the prognosis of patients with solid tumors.

Structural plasticity of methyllysine recognition by the tandem tudor domain of 53BP1.

p53 is dynamically regulated through various posttranslational modifications (PTMs), which differentially modulate its function and stability. The dimethylated marks p53K370me2 and p53K382me2 are associated with p53 activation or stabilization and both are recognized by the tandem Tudor domain (TTD) of 53BP1, a p53 cofactor. Here we detail the molecular mechanisms for the recognition of p53K370me2 and p53K382me2 by 53BP1. The solution structures of TTD in complex with the p53K370me2 and p53K382me2 peptides show a remarkable plasticity of 53BP1 in accommodating these diverse dimethyllysine-containing sequences. We demonstrate that dimeric TTDs are capable of interacting with the two PTMs on a single p53K370me2K382me2 peptide, greatly strengthening the 53BP1-p53 interaction. Analysis of binding affinities of TTD toward methylated p53 and histones reveals strong preference of 53BP1 for p53K382me2, H4K20me2, and H3K36me2 and suggests a possible role of multivalent contacts of 53BP1 in p53 targeting to and accumulation at the sites of DNA damage.