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Kidney & Blood Pressure Research 2016Renal reabsorption of inorganic phosphate (Pi) is mediated by SLC34 and SLC20 Na+/Pi-cotransporters the abundance of which is under hormonal control. Extracellular Pi...
BACKGROUND/AIMS
Renal reabsorption of inorganic phosphate (Pi) is mediated by SLC34 and SLC20 Na+/Pi-cotransporters the abundance of which is under hormonal control. Extracellular Pi itself also regulates the expression of cotransporters and the concentration of Pi-regulating hormones, though the signaling pathways are largely unknown. Here, we explored the mechanisms that allow renal proximal cells to adapt to changes in the concentration of Pi.
METHODS
opossum kidney (OK) cells, a model of proximal epithelia, were incubated with different concentrations of Pi in the absence/presence of phosphonoformic acid (PFA), a Pi-analogue and SLC34-inhibitor, and of inhibitors of kinases involved in hormonal control of Pi-homeostasis; cells cultured in normal media were treated with uncouplers of oxidative phosphorylation. Then, the intracellular concentration of ATP and/or the Pi-transport capacity of the cultures were analyzed.
RESULTS
luminal Pi regulates the Pi-transport and the intracellular ATP levels. Changes in ATP seem secondary to alterations in Pi-transport, rather than ATP acting as a signal. Adaptation of Pi-transport to high Pi was not mimicked by PFA. Transport adaptation was blocked by PFA but not by kinase inhibitors.
CONCLUSIONS
in OK cells, adaptation of Pi-transport to luminal Pi does not depend on the same signaling pathways involved in hormonal regulation.
Topics: Adenosine Triphosphate; Animals; Biological Transport; Cells, Cultured; Foscarnet; Kidney; Kidney Tubules, Proximal; Opossums; Phosphates; Protein Kinase Inhibitors; Signal Transduction; Sodium-Phosphate Cotransporter Proteins, Type II
PubMed: 27165344
DOI: 10.1159/000443432 -
Biological & Pharmaceutical Bulletin 2016Bisphosphonates (BPs) are typical anti-bone-resorptive drugs, with nitrogen-containing BPs (N-BPs) being stronger than non-nitrogen-containing BPs (non-N-BPs). However,...
Bisphosphonates (BPs) are typical anti-bone-resorptive drugs, with nitrogen-containing BPs (N-BPs) being stronger than non-nitrogen-containing BPs (non-N-BPs). However, N-BPs have inflammatory/necrotic effects, while the non-N-BPs clodronate and etidronate lack such side effects. Pharmacological studies have suggested that clodronate and etidronate can (i) prevent the side effects of N-BPs in mice via inhibition of the phosphate transporter families SLC20 and/or SLC34, through which N-BPs enter soft-tissue cells, and (ii) also inhibit the phosphate transporter family SLC17. Vesicular transporters for the pain transmitters glutamate and ATP belong to the SLC17 family. Here, we examined the hypothesis that clodronate and etidronate may enter neurons through SLC20/34, then inhibit SLC17-mediated transport of glutamate and/or ATP, resulting in their decrease, and thereby produce analgesic effects. We analyzed in mice the effects of various agents [namely, intrathecally injected clodronate, etidronate, phosphonoformic acid (PFA; an inhibitor of SLC20/34), and agonists of glutamate and ATP receptors] on the nociceptive responses to intraplantar injection of capsaicin. Clodronate and etidronate produced analgesic effects, and these effects were abolished by PFA. The analgesic effects were reduced by N-methyl-D-aspartate (agonist of the NMDA receptor, a glutamate receptor) and α,β-methylene ATP (agonist of the P2X-receptor, an ATP receptor). SLC20A1, SLC20A2, and SLC34A1 were detected within the mouse lumbar spinal cord. Although we need direct evidence, these results support the above hypothesis. Clodronate and etidronate may be representatives of a new type of analgesic drug. Such drugs, with both anti-bone-resorptive and unique analgesic effects without the adverse effects associated with N-BPs, might be useful for osteoporosis.
Topics: Acetic Acid; Adenosine Triphosphate; Analgesics; Animals; Bone Density Conservation Agents; Capsaicin; Clodronic Acid; Etidronic Acid; Excitatory Amino Acid Agonists; Foscarnet; Glutamic Acid; Lumbar Vertebrae; Mice; Mice, Inbred BALB C; N-Methylaspartate; Pain; Sodium-Phosphate Cotransporter Proteins; Spinal Cord; Substance P
PubMed: 27150146
DOI: 10.1248/bpb.b15-00882 -
Antimicrobial Agents and Chemotherapy Jun 2016Eight in vitro selection experiments under brincidofovir pressure elicited the known cytomegalovirus DNA polymerase amino acid substitutions N408K and V812L and the...
Eight in vitro selection experiments under brincidofovir pressure elicited the known cytomegalovirus DNA polymerase amino acid substitutions N408K and V812L and the novel exonuclease domain substitutions D413Y, E303D, and E303G, which conferred ganciclovir and cidofovir resistance with 6- to 11-fold resistance to brincidofovir or 17-fold when E303G was combined with V812L. The new exonuclease domain I resistance mutations selected under brincidofovir pressure add to the single instance previously reported and show the expected patterns of cross-resistance.
Topics: Antiviral Agents; Cidofovir; Cytomegalovirus; Cytomegalovirus Infections; Cytosine; DNA-Directed DNA Polymerase; Drug Resistance, Viral; Foscarnet; Ganciclovir; Gene Expression; Humans; Microbial Sensitivity Tests; Mutation; Organophosphonates; Protein Domains; Viral Proteins
PubMed: 27044553
DOI: 10.1128/AAC.00214-16 -
Nephrology (Carlton, Vic.) Jul 2016Cytomegalovirus (CMV) infection is the most common infectious complication following solid organ transplantation. Ganciclovir (GCV)-resistant CMV infection may be fatal,...
Cytomegalovirus (CMV) infection is the most common infectious complication following solid organ transplantation. Ganciclovir (GCV)-resistant CMV infection may be fatal, and is difficult to treat while avoiding allograft rejection. A 31-year-old woman received a second ABO-incompatible kidney transplant, from her father. Induction therapy consisted of basiliximab and rituximab followed by maintenance immunosuppression with tacrolimus, mycophenolate mofetil, and methylprednisolone. Her CMV serostatus was D(+) /R(-) at second transplant and she received prophylactic low-dose valganciclovir (VGCV). BK polyoma virus nephropathy (BKVN) developed 7 months after transplant concurrent with CMV hepatitis and retinitis. VGCV was increased to a therapeutic dose combined with reduced immunosuppression with minimal methylprednisolone (2 mg/day) and everolimus (0.5 mg/day). However, pp65 antigenaemia continued to increase for 6 weeks. Her CMV was defined as ganciclovir (GCV)-resistant. Foscarnet was therefore administered and her CMV disease resolved within 2 weeks. Kidney allograft dysfunction developed 9 months after transplant, and graft biopsy showed tubulointerstitial injury with crystal deposition suggesting foscarnet nephrotoxicity, with no findings of BKVN or rejection. Kidney function recovered after cessation of foscarnet and the patient had good graft function 18 months after transplant. This case demonstrates the successful use of foscarnet to treat GCV-resistant CMV infection after ABO-incompatible kidney transplant complicated with BKVN, without acute allograft rejection. This case further highlights the need to establish appropriate management for CMV D(+) /R(-) patients to avoid the acquisition of GCV-resistant gene mutations.
Topics: Adult; Allografts; Antiviral Agents; Biopsy; Cytomegalovirus Infections; Drug Resistance, Viral; Female; Foscarnet; Ganciclovir; Humans; Immunocompromised Host; Immunohistochemistry; Immunosuppressive Agents; Kidney Transplantation; Time Factors; Treatment Outcome
PubMed: 26970406
DOI: 10.1111/nep.12767 -
Journal of Virology Apr 2016Many viruses have the capacity to prevent a cell from being infected by a second virus, often termed superinfection exclusion. Alphaherpesviruses, including the human...
UNLABELLED
Many viruses have the capacity to prevent a cell from being infected by a second virus, often termed superinfection exclusion. Alphaherpesviruses, including the human pathogen herpes simplex virus 1 (HSV-1) and the animal herpesvirus pseudorabies virus (PRV), encode a membrane-bound glycoprotein, gD, that can interfere with subsequent virion entry. We sought to characterize the timing and mechanism of superinfection exclusion during HSV-1 and PRV infection. To this end, we utilized recombinant viruses expressing fluorescent protein (FP) markers of infection that allowed the visualization of viral infections by microscopy and flow cytometry as well as the differentiation of viral progeny. Our results demonstrated the majority of HSV-1- and PRV-infected cells establish superinfection exclusion by 2 h postinfection. The modification of viral infections by virion inactivation and phosphonoacetic acid, cycloheximide, and actinomycin D treatments indicated new protein synthesis is needed to establish superinfection exclusion. Primary infection with gene deletion PRV recombinants identified that new gD expression is not required to establish superinfection exclusion of a secondary viral inoculum. We also identified the timing of coinfection events during axon-to-cell spread, with most occurring within a 2-h window, suggesting a role for cellular superinfection exclusion during neuroinvasive spread of infection. In summary, we have characterized a gD-independent mechanism of superinfection exclusion established by two members of the alphaherpesvirus family and identified a potential role of exclusion during the pathogenic spread of infection.
IMPORTANCE
Superinfection exclusion is a widely observed phenomenon initiated by a primary viral infection to prevent further viruses from infecting the same cell. The capacity for alphaherpesviruses to infect the same cell impacts rates of interviral recombination and disease. Interviral recombination allows genome diversification, facilitating the development of resistance to antiviral therapeutics and evasion of vaccine-mediated immune responses. Our results demonstrate superinfection exclusion occurs early, through a gD-independent process, and is important in the directed spread of infection. Identifying when and where in an infected host viral genomes are more likely to coinfect the same cell and generate viral recombinants will enhance the development of effective antiviral therapies and interventions.
Topics: Animals; Cell Line; Cells, Cultured; Chlorocebus aethiops; Herpesvirus 1, Human; Herpesvirus 1, Suid; Rats; Reassortant Viruses; Superinfection; Vero Cells; Viral Envelope Proteins
PubMed: 26842480
DOI: 10.1128/JVI.00089-16 -
Biochemistry Feb 2016We examined the impact of two clinically approved anti-herpes drugs, acyclovir and Forscarnet (phosphonoformate), on the exonuclease activity of the herpes simplex...
Effects of Acyclovir, Foscarnet, and Ribonucleotides on Herpes Simplex Virus-1 DNA Polymerase: Mechanistic Insights and a Novel Mechanism for Preventing Stable Incorporation of Ribonucleotides into DNA.
We examined the impact of two clinically approved anti-herpes drugs, acyclovir and Forscarnet (phosphonoformate), on the exonuclease activity of the herpes simplex virus-1 DNA polymerase, UL30. Acyclovir triphosphate and Foscarnet, along with the closely related phosphonoacetic acid, did not affect exonuclease activity on single-stranded DNA. Furthermore, blocking the polymerase active site due to either binding of Foscarnet or phosphonoacetic acid to the E-DNA complex or polymerization of acyclovir onto the DNA also had a minimal effect on exonuclease activity. The inability of the exonuclease to excise acyclovir from the primer 3'-terminus results from the altered sugar structure directly impeding phosphodiester bond hydrolysis as opposed to inhibiting binding, unwinding of the DNA by the exonuclease, or transfer of the DNA from the polymerase to the exonuclease. Removing the 3'-hydroxyl or the 2'-carbon from the nucleotide at the 3'-terminus of the primer strongly inhibited exonuclease activity, although addition of a 2'-hydroxyl did not affect exonuclease activity. The biological consequences of these results are twofold. First, the ability of acyclovir and Foscarnet to block dNTP polymerization without impacting exonuclease activity raises the possibility that their effects on herpes replication may involve both direct inhibition of dNTP polymerization and exonuclease-mediated destruction of herpes DNA. Second, the ability of the exonuclease to rapidly remove a ribonucleotide at the primer 3'-terminus in combination with the polymerase not efficiently adding dNTPs onto this primer provides a novel mechanism by which the herpes replication machinery can prevent incorporation of ribonucleotides into newly synthesized DNA.
Topics: Acyclovir; Antiviral Agents; Catalytic Domain; DNA, Single-Stranded; DNA-Directed DNA Polymerase; Exodeoxyribonucleases; Foscarnet; Herpesvirus 1, Human; Hydrolysis; Kinetics; Models, Molecular; Molecular Structure; Nucleic Acid Synthesis Inhibitors; Recombinant Proteins; Ribonucleotides; Substrate Specificity; Viral Proteins
PubMed: 26836009
DOI: 10.1021/acs.biochem.6b00065 -
Organic & Biomolecular Chemistry Feb 2016As α-carboxy nucleoside phosphonates (α-CNPs) have demonstrated a novel mode of action of HIV-1 reverse transcriptase inhibition, structurally related derivatives were...
As α-carboxy nucleoside phosphonates (α-CNPs) have demonstrated a novel mode of action of HIV-1 reverse transcriptase inhibition, structurally related derivatives were synthesized, namely the malonate 2, the unsaturated and saturated bisphosphonates 3 and 4, respectively and the amide 5. These compounds were evaluated for inhibition of HIV-1 reverse transcriptase in cell-free assays. The importance of the α-carboxy phosphonoacetic acid moiety for achieving reverse transcriptase inhibition, without the need for prior phosphorylation, was confirmed. The malonate derivative 2 was less active by two orders of magnitude than the original α-CNPs, while displaying the same pattern of kinetic behavior; interestingly the activity resides in the “L”-enantiomer of 2, as seen with the earlier series of α-CNPs. A crystal structure with an RT/DNA complex at 2.95 Å resolution revealed the binding of the “L”-enantiomer of 2, at the polymerase active site with a weaker metal ion chelation environment compared to 1a (T-α-CNP) which may explain the lower inhibitory activity of 2.
Topics: Anti-HIV Agents; Dose-Response Relationship, Drug; HIV Reverse Transcriptase; HIV-1; Models, Molecular; Molecular Structure; Nucleosides; Organophosphonates; Reverse Transcriptase Inhibitors; Structure-Activity Relationship
PubMed: 26813581
DOI: 10.1039/c5ob02507a -
Japanese Journal of Infectious Diseases Nov 2016Cytomegalovirus (CMV) retinitis is typically diagnosed in patient with AIDS and those who underwent allogeneic hematopoietic cell transplant. However, it may develop in... (Review)
Review
Cytomegalovirus (CMV) retinitis is typically diagnosed in patient with AIDS and those who underwent allogeneic hematopoietic cell transplant. However, it may develop in patients with acute lymphoblastic leukemia (ALL) who have not undergone hematopoietic cell transplantation. To increase awareness of CMV retinitis in this group, we describe 3 patients ages 3, 9, and 12, with ALL who developed CMV retinitis. The diagnosis of CMV retinitis was made on the basis of ophthalmological findings suggesting typical retinal lesions. In 2 cases, CMV DNAemia was present, while in 1 patient CMV DNA was detected only in vitreous fluid using the PCR technique. All cases were treated with intravenous ganciclovir for 2 or 3 weeks as induction therapy, followed by oral valganciclovir prophylaxis. Initially, active retinitis lesions resolved in all cases; however, in 1 patient CMV retinitis relapsed 3 times during follow-up. In this case, by using foscarnet therapy, satisfactory responses were achieved and the progression of CMV retinitis lesions stopped and eventually regressed.
Topics: Administration, Intravenous; Administration, Oral; Adolescent; Antiviral Agents; Child; Child, Preschool; Cytomegalovirus Retinitis; DNA, Viral; Eye; Foscarnet; Ganciclovir; Humans; Male; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Valganciclovir; Viremia; Vitreous Body
PubMed: 26567834
DOI: 10.7883/yoken.JJID.2015.223 -
The Journal of Organic Chemistry Oct 2015A versatile and general catalytic strategy has been developed for the α-arylation of phosphonoacetates utilizing parallel microscale experimentation. These...
A versatile and general catalytic strategy has been developed for the α-arylation of phosphonoacetates utilizing parallel microscale experimentation. These α-substituted phosphonoacetates are widely useful, notably as substrates in the Horner-Wadsworth-Emmons-type olefinations. However, the current routes to these products involve harsh conditions, limiting the variety of functionality. The reported method can be used with a variety of aryl chlorides and aryl bromides, including several heterocyclic examples.
Topics: Alkenes; Catalysis; Heterocyclic Compounds; Molecular Structure; Phosphonoacetic Acid; Stereoisomerism
PubMed: 26405824
DOI: 10.1021/acs.joc.5b01887 -
Journal of Virology Nov 2015Viruses modulate cellular processes and metabolism in diverse ways, but these are almost universally studied in the infected cell itself. Here, we study spatial...
UNLABELLED
Viruses modulate cellular processes and metabolism in diverse ways, but these are almost universally studied in the infected cell itself. Here, we study spatial organization of DNA synthesis during multiround transmission of herpes simplex virus (HSV) using pulse-labeling with ethynyl nucleotides and cycloaddition of azide fluorophores. We report a hitherto unknown and unexpected outcome of virus-host interaction. Consistent with the current understanding of the single-step growth cycle, HSV suppresses host DNA synthesis and promotes viral DNA synthesis in spatially segregated compartments within the cell. In striking contrast, during progressive rounds of infection initiated at a single cell, we observe that infection induces a clear and pronounced stimulation of cellular DNA replication in remote uninfected cells. This induced DNA synthesis was observed in hundreds of uninfected cells at the extended border, outside the perimeter of the progressing infection. Moreover, using pulse-chase analysis, we show that this activation is maintained, resulting in a propagating wave of host DNA synthesis continually in advance of infection. As the virus reaches and infects these activated cells, host DNA synthesis is then shut off and replaced with virus DNA synthesis. Using nonpropagating viruses or conditioned medium, we demonstrate a paracrine effector of uninfected cell DNA synthesis in remote cells continually in advance of infection. These findings have significant implications, likely with broad applicability, for our understanding of the ways in which virus infection manipulates cell processes not only in the infected cell itself but also now in remote uninfected cells, as well as of mechanisms governing host DNA synthesis.
IMPORTANCE
We show that during infection initiated by a single particle with progressive cell-cell virus transmission (i.e., the normal situation), HSV induces host DNA synthesis in uninfected cells, mediated by a virus-induced paracrine effector. The field has had no conception that this process occurs, and the work changes our interpretation of virus-host interaction during advancing infection and has implications for understanding controls of host DNA synthesis. Our findings demonstrate the utility of chemical biology techniques in analysis of infection processes, reveal distinct processes when infection is examined in multiround transmission versus single-step growth curves, and reveal a hitherto-unknown process in virus infection, likely relevant for other viruses (and other infectious agents) and for remote signaling of other processes, including transcription and protein synthesis.
Topics: Animals; Azides; Bacterial Proteins; Cell Line; Chlorocebus aethiops; DNA Replication; Herpes Simplex; Host-Pathogen Interactions; Humans; Luminescent Proteins; Paracrine Communication; Phosphonoacetic Acid; Simplexvirus; Vero Cells; Viral Plaque Assay; Virus Internalization
PubMed: 26311877
DOI: 10.1128/JVI.01950-15