Ferroptosis: process and function

Ferroptosis is a recently recognized form of regulated cell death. It is characterized morphologically by the presence of smaller than normal mitochondria with condensed mitochondrial membrane densities, reduction or vanishing of mitochondria crista, and outer mitochondrial membrane rupture. It can be induced by experimental compounds (e.g., erastin, Ras-selective lethal small molecule 3, and buthionine sulfoximine) or clinical drugs (e.g., sulfasalazine, sorafenib, and artesunate) in cancer cells and certain normal cells (e.g., kidney tubule cells, neurons, fibroblasts, and T cells). Activation of mitochondrial voltage-dependent anion channels and mitogen-activated protein kinases, upregulation of endoplasmic reticulum stress, and inhibition of cystine/glutamate antiporter is involved in the induction of ferroptosis. This process is characterized by the accumulation of lipid peroxidation products and lethal reactive oxygen species (ROS) derived from iron metabolism and can be pharmacologically inhibited by iron chelators (e.g., deferoxamine and desferrioxamine mesylate) and lipid peroxidation inhibitors (e.g., ferrostatin, liproxstatin, and zileuton). Glutathione peroxidase 4, heat shock protein beta-1, and nuclear factor erythroid 2-related factor 2 function as negative regulators of ferroptosis by limiting ROS production and reducing cellular iron uptake, respectively. In contrast, NADPH oxidase and p53 (especially acetylation-defective mutant p53) act as positive regulators of ferroptosis by promotion of ROS production and inhibition of expression of SLC7A11 (a specific light-chain subunit of the cystine/glutamate antiporter), respectively. Misregulated ferroptosis has been implicated in multiple physiological and pathological processes, including cancer cell death, neurotoxicity, neurodegenerative diseases, acute renal failure, drug-induced hepatotoxicity, hepatic and heart ischemia/reperfusion injury, and T-cell immunity. In this review, we summarize the regulation mechanisms and signaling pathways of ferroptosis and discuss the role of ferroptosis in disease.

Regulation of protein kinase C zeta by PI 3-kinase and PDK-1

BACKGROUND

Protein kinase C zeta (PKC zeta) is a member of the PKC family of enzymes and is involved in a wide range of physiological processes including mitogenesis, protein synthesis, cell survival and transcriptional regulation. PKC zeta has received considerable attention recently as a target of phosphoinositide 3-kinase (PI 3-kinase), although the mechanism of PKC zeta activation is, as yet, unknown. Recent reports have also shown that the phosphoinositide-dependent protein kinase-1 (PDK-1), which binds with high affinity to the PI 3-kinase lipid product phosphatidylinositol-3,4,5-trisphosphate (Ptdins-3,4,5-P3), phosphorylates and potently activates two other PI 3-kinase targets, the protein kinases Akt/PKB and p70S6K. We therefore investigated whether PDK-1 is the kinase that activates PKC zeta.

RESULTS

In vivo, PI 3-kinase is both necessary and sufficient to activate PKC zeta. PDK-1 phosphorylates and activates PKC zeta in vivo, and we have shown that this is due to phosphorylation of threonine 410 in the PKC zeta activation loop. In vitro, PDK-1 phosphorylates and activates PKC zeta in a Ptdins-3,4,5-P3-enhanced manner. PKC zeta and PDK-1 are associated in vivo, and membrane targeting of PKC zeta renders it constitutively active in cells.

CONCLUSIONS

Our results have identified PDK-1 as the kinase that phosphorylates and activates PKC zeta in the PI 3-kinase signaling pathway. This phosphorylation and activation of PKC zeta by PDK-1 is enhanced in the presence of Ptdins-3,4-5-P3. Consistent with the notion that PKCs are enzymes that are regulated at the plasma membrane, a membrane-targeted PKC zeta is constitutively active in the absence of agonist stimulation. The association between PKC zeta and PDK-1 reveals extensive cross-talk between enzymes in the PI 3-kinase signaling pathway.

Renin-Angiotensin System Inhibitors and Kidney and Cardiovascular Outcomes in Patients With CKD: A Bayesian Network Meta-analysis of Randomized Clinical Trials

BACKGROUND

There is much uncertainty regarding the relative effects of angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) in populations with chronic kidney disease (CKD).

STUDY DESIGN

Systematic review and Bayesian network meta-analysis.

SETTING & POPULATION

Patients with CKD treated with renin-angiotensin system (RAS) inhibitors.

SELECTION CRITERIA FOR STUDIES

Randomized trials in patients with CKD treated with RAS inhibitors.

PREDICTOR

ACE inhibitors and ARBs compared to each other and to placebo and active controls.

OUTCOME

Primary outcome was kidney failure; secondary outcomes were major cardiovascular events, all-cause death.

RESULTS

119 randomized controlled trials (n = 64,768) were included. ACE inhibitors and ARBs reduced the odds of kidney failure by 39% and 30% (ORs of 0.61 [95% credible interval, 0.47-0.79] and 0.70 [95% credible interval, 0.52-0.89]), respectively, compared to placebo, and by 35% and 25% (ORs of 0.65 [95% credible interval, 0.51-0.80] and 0.75 [95% credible interval, 0.54-0.97]), respectively, compared with other active controls, whereas other active controls did not show evidence of a significant effect on kidney failure. Both ACE inhibitors and ARBs produced odds reductions for major cardiovascular events (ORs of 0.82 [95% credible interval, 0.71-0.92] and 0.76 [95% credible interval, 0.62-0.89], respectively) versus placebo. Comparisons did not show significant effects on risk for cardiovascular death. ACE inhibitors but not ARBs significantly reduced the odds of all-cause death versus active controls (OR, 0.72; 95% credible interval, 0.53-0.92). Compared with ARBs, ACE inhibitors were consistently associated with higher probabilities of reducing kidney failure, cardiovascular death, or all-cause death.

LIMITATIONS

Trials with RAS inhibitor therapy were included; trials with direct comparisons of other active controls with placebo were not included.

CONCLUSIONS

Use of ACE inhibitors or ARBs in people with CKD reduces the risk for kidney failure and cardiovascular events. ACE inhibitors also reduced the risk for all-cause mortality and were possibly superior to ARBs for kidney failure, cardiovascular death, and all-cause mortality in patients with CKD, suggesting that they could be the first choice for treatment in this population.

Herpes simplex virus glycoprotein D can bind to poliovirus receptor-related protein 1 or herpesvirus entry mediator, two structurally unrelated mediators of virus entry

Several cell membrane proteins have been identified as herpes simplex virus (HSV) entry mediators (Hve). HveA (formerly HVEM) is a member of the tumor necrosis factor receptor family, whereas the poliovirus receptor-related proteins 1 and 2 (PRR1 and PRR2, renamed HveC and HveB) belong to the immunoglobulin superfamily. Here we show that a truncated form of HveC directly binds to HSV glycoprotein D (gD) in solution and at the surface of virions. This interaction is dependent on the native conformation of gD but independent of its N-linked glycosylation. Complex formation between soluble gD and HveC appears to involve one or two gD molecules for one HveC protein. Since HveA also mediates HSV entry by interacting with gD, we compared both structurally unrelated receptors for their binding to gD. Analyses of several gD variants indicated that structure and accessibility of the N-terminal domain of gD, essential for HveA binding, was not necessary for HveC interaction. Mutations in functional regions II, III, and IV of gD had similar effects on binding to either HveC or HveA. Competition assays with neutralizing anti-gD monoclonal antibodies (MAbs) showed that MAbs from group Ib prevented HveC and HveA binding to virions. However, group Ia MAbs blocked HveC but not HveA binding, and conversely, group VII MAbs blocked HveA but not HveC binding. Thus, we propose that HSV entry can be mediated by two structurally unrelated gD receptors through related but not identical binding with gD.

Strange attractors: DAMPs and autophagy link tumor cell death and immunity

Resistance to ‘apoptotic' cell death is one of the major hallmarks of cancer, contributing to tumor development and therapeutic resistance. Damage-associated molecular patterns (DAMPs) are molecules released or exposed by dead, dying, injured, or stressed non-apoptotic cells, with multiple roles in inflammation and immunity. Release of DAMPs not only contributes to tumor growth and progression but also mediates skewing of antitumor immunity during so-called immunogenic tumor cell death (ICD). Autophagy is a lysosome-mediated homeostatic degradation process in which cells digest their own effete organelles and macromolecules to meet bioenergetic needs and enable protein synthesis. For tumor cells, autophagy is a double-edged sword. Autophagy, in balance with apoptosis, can function as a tumor suppressor; autophagy deficiency, associated with alterations in apoptosis, initiates tumorigenesis in many settings. In contrast, autophagy-related stress tolerance generally promotes cell survival, which enables tumor growth and promotes therapeutic resistance. Most anticancer therapies promote DAMP release and enhance autophagy. Autophagy not only regulates DAMP release and degradation, but also is triggered and regulated by DAMPs. This interplay between autophagy and DAMPs, serving as ‘strange attractors' in the dynamic system that emerges in cancer, regulates the effectiveness of antitumor treatment. This interplay also shapes the immune response to dying cells upon ICD, culling the least fit tumor cells and promoting survival of others. Thus, DAMPs and autophagy are suitable emergent targets for cancer therapy, considering their more nuanced role in tumor progression.

Effect of statin therapy on cardiovascular and renal outcomes in patients with chronic kidney disease: a systematic review and meta-analysis

AIMS

The effects of statin therapy in patients with chronic kidney disease (CKD) remain uncertain. We undertook a systematic review and meta-analysis to investigate the effects of statin on major clinical outcomes.

METHODS AND RESULTS

We systematically searched MEDLINE, Embase, and the Cochrane Library for trials published between 1970 and November 2011. We included prospective, randomized, controlled trials assessing the effects of statins on cardiovascular outcomes in people with kidney disease. Summary estimates of relative risk (RR) reductions were calculated with a random effects model. Thirty-one trials that include at least one event were identified, providing data for 48 429 patients with CKD, including 6690 major cardiovascular events and 6653 deaths. Statin therapy produced a 23% RR reduction (16-30) for major cardiovascular events (P<0.001), an 18% RR reduction (8-27) for coronary events, and 9% (1-16) reduction in cardiovascular or all-cause deaths, but had no significantly effect on stroke (21%, -12 to 44) or no clear effect on kidney failure events (5%, -1 to 10). Adverse events were not significantly increased by statins, including hepatic (RR 1.13, 95% CI 0.92-1.39) or muscular disorders (RR 1.02, 95% CI 0.95-1.09). Subgroup analysis demonstrated the relative effects of statin therapy in CKD were significantly reduced in people with advanced CKD (P < 0.001) but that the absolute risk reductions were comparable.

CONCLUSION

Statin therapy reduces the risk of major cardiovascular events in patients with chronic kidney disease including those receiving dialysis.

Monoclonal antibodies to distinct sites on herpes simplex virus (HSV) glycoprotein D block HSV binding to HVEM

HVEM (for herpesvirus entry mediator) is a member of the tumor necrosis factor receptor superfamily and mediates entry of many strains of herpes simplex virus (HSV) into normally nonpermissive Chinese hamster ovary (CHO) cells. We used sucrose density centrifugation to demonstrate that purified HSV-1 KOS virions bind directly to a soluble, truncated form of HVEM (HVEMt) in the absence of any other cell-associated components. Therefore, HVEM mediates HSV entry by serving as a receptor for the virus. We previously showed that soluble, truncated forms of HSV glycoprotein D (gDt) bind to HVEMt in vitro. Here we show that antibodies specific for gD, but not the other entry glycoproteins gB, gC, or the gH/gL complex, completely block HSV binding to HVEM. Thus, virion gD is the principal mediator of HSV binding to HVEM. To map sites on virion gD which are necessary for its interaction with HVEM, we preincubated virions with gD-specific monoclonal antibodies (MAbs). MAbs that recognize antigenic sites Ib and VII of gD were the only MAbs which blocked the HSV-HVEM interaction. MAbs from these two groups failed to coprecipitate HVEMt in the presence of soluble gDt, whereas the other anti-gD MAbs coprecipitated HVEMt and gDt. Previous mapping data indicated that site VII includes amino acids 11 to 19 and site Ib includes 222 to 252. The current experiments indicate that these sites contain residues important for HSV binding to HVEM. Group Ib and VII MAbs also blocked HSV entry into HVEM-expressing CHO cells. These results suggest that the mechanism of neutralization by these MAbs is via interference with the interaction between gD in the virus and HVEM on the cell. Group Ia and II MAbs failed to block HSV binding to HVEM yet still neutralized HVEM-mediated entry, suggesting that these MAbs block entry at a step other than HVEM binding.

The first immunoglobulin-like domain of HveC is sufficient to bind herpes simplex virus gD with full affinity, while the third domain is involved in oligomerization of HveC

The human herpesvirus entry mediator C (HveC/PRR1) is a member of the immunoglobulin family used as a cellular receptor by the alphaherpesviruses herpes simplex virus (HSV), pseudorabies virus, and bovine herpesvirus type 1. We previously demonstrated direct binding of the purified HveC ectodomain to purified HSV type 1 (HSV-1) and HSV-2 glycoprotein D (gD). Here, using a baculovirus expression system, we constructed and purified truncated forms of the receptor containing one [HveC(143t)], two [HveC(245t)], or all three immunoglobulin-like domains [HveC(346t)] of the extracellular region. All three constructs were equally able to compete with HveC(346t) for gD binding. The variable domain bound to virions and blocked HSV infection as well as HveC(346t). Thus, all of the binding to the receptor occurs within the first immunoglobulin-like domain, or V-domain, of HveC. These data confirm and extend those of Cocchi et al. (F. Cocchi, M. Lopez, L. Menotti, M. Aoubala, P. Dubreuil, and G. Campadelli-Fiume, Proc. Natl. Acad. Sci. USA 95:15700, 1998). Using biosensor analysis, we measured the affinity of binding of gD from HSV strains KOS and rid1 to two forms of HveC. Soluble gDs from the KOS strain of HSV-1 had the same affinity for HveC(346t) and HveC(143t). The mutant gD(rid1t) had an increased affinity for HveC(346t) and HveC(143t) due to a faster rate of complex formation. Interestingly, we found that HveC(346t) was a tetramer in solution, whereas HveC(143t) and HveC(245t) formed dimers, suggesting a role for the third immunoglobulin-like domain of HveC in oligomerization. In addition, the stoichiometry between gD and HveC appeared to be influenced by the level of HveC oligomerization.

Interaction between PLA2R1 and HLA-DQA1 variants associates with anti-PLA2R antibodies and membranous nephropathy

Risk alleles at genome loci containing phospholipase A2 receptor 1 (PLA2R1) and HLA-DQA1 closely associate with idiopathic membranous nephropathy (IMN) in the European population, but it is unknown whether a similar association exists in the Chinese population and whether high-risk alleles promote the development of anti-PLA2R antibodies. Here, we genotyped 2132 Chinese individuals, including 1112 patients with IMN and 1020 healthy controls, for three single nucleotide polymorphisms (SNPs) within PLA2R1 and three SNPs within HLA genes. We also selected 71 patients, with varying genotypes, to assess for circulating anti-PLA2R antibody and for PLA2R expression in glomeruli. Three SNPs within PLA2R1 and one SNP within HLA-DQA1 strongly associated with IMN, and we noted gene-gene interactions involving these SNPs. Furthermore, these risk alleles strongly associated with the presence of anti-PLA2R antibodies and glomerular PLA2R expression. Among individuals who carried risk alleles for both genes, 73% had anti-PLA2R antibodies and 75% expressed PLA2R in glomeruli. In contrast, among individuals who carried protective genotypes of both genes, none had anti-PLA2R antibodies and glomerular expression of PLA2R was weak or absent. In conclusion, the interaction between PLA2R1 and HLA-DQA1 risk alleles associates with the development of IMN in the Chinese population. Individuals carrying risk alleles are predisposed to the generation of circulating anti-PLA2R autoantibodies, which may contribute to the development of IMN.

Examination of the kinetics of herpes simplex virus glycoprotein D binding to the herpesvirus entry mediator, using surface plasmon resonance

Previously, we showed that truncated soluble forms of herpes simplex virus (HSV) glycoprotein D (gDt) bound directly to a truncated soluble form of the herpesvirus entry mediator (HveAt, formerly HVEMt), a cellular receptor for HSV. The purpose of the present study was to determine the affinity of gDt for HveAt by surface plasmon resonance and to compare and contrast the kinetics of an expanded panel of gDt variants in binding to HveAt in an effort to better understand the mechanism of receptor binding and virus entry. Both HveAt and gDt are dimers in solution and interact with a 2:1 stoichiometry. With HveAt, gD1(306t) (from the KOS strain of HSV-1) had a dissociation constant (KD) of 3.2 x 10(-6) M and gD2(306t) had a KD of 1.5 x 10(-6) M. The interaction between gDt and HveAt fits a 1:1 Langmuir binding model, i.e., two dimers of HveAt may act as one binding unit to interact with one dimer of gDt as the second binding unit. A gD variant lacking all signals for N-linked oligosaccharides had an affinity for HveAt similar to that of gD1(306t). A variant lacking the bond from cysteine 1 to cysteine 5 had an affinity for HveAt that did not differ from that of the wild type. However, variants with double cysteine mutations that eliminated either of the other two disulfide bonds showed decreased affinity for HveAt. This result suggests that two of the three disulfide bonds of gD are important for receptor binding. Four nonfunctional gDt variants, each representing one functional domain of gD, were also studied. Mutations in functional regions I and II drastically decreased the affinity of gDt for HveAt. Surprisingly, a variant with an insertion in functional region III had a wild-type level of affinity for HveAt, suggesting that this domain may function in virus entry at a step other than receptor binding. A variant with a deletion in functional region IV [gD1(Delta290-299t)] exhibited a 100-fold enhancement in affinity for HveAt (KD = 3.3 x 10(-8) M) due mainly to a 40-fold increase in its kinetic on rate. This agrees with the results of other studies showing the enhanced ability of gD1(Delta290-299t) to block infection. Interestingly, all the variants with decreased affinities for HveAt exhibited decreased kinetic on rates but only minor changes in their kinetic off rates. The results suggest that once the complex between gDt and HveAt forms, its stability is unaffected by a variety of changes in gD.

Microbiological characterization in children with aggressive periodontitis

The objective of this study was to characterize the subgingival microbiota of African-American children with Localized Aggressive Periodontitis (LAP). Fifty-one children were included. Subgingival plaque samples were taken from diseased (DD) and healthy sites (DH) in LAP and from healthy sites in HS and HC and analyzed by 16S rRNA-based microarrays. Aggregatibacter actinomycetemcomitans (Aa) was the only species found to be both more prevalent (OR = 8.3, p = 0.0025) and abundant (p < 0.01) in DD. Filifactor alocis (Fa) was also found to be more prevalent in DD (OR 2.31, CI 1.06-5.01, p = 0.03). Most prevalent species in healthy sites were Selenomonas spp, Veillonella spp, Streptococcus spp, Bergeyella sp, and Kingella oralis. Overall, Streptococcus spp, Campylobacter gracilis, Capnocytophaga granulosa, Haemophilus parainfluenzae, and Lautropia mirabilis were most abundant in healthy children, while Aa, Fa, Tannerella sp, Solobacterium moorei, Parvimonas micra, and Capnocytophaga sp were most abundant in LAP. Based on a comprehensive analysis with 16S rRNA-based microarrays, Aa was strongly associated and site-specific in LAP. In contrast, other species were found to be associated with healthy sites and individuals (ClinicalTrials.gov number CT01330719).

ABBREVIATIONS

healthy site in healthy sibling (HS); healthy site in healthy control child (HC).

Antiviral activity of arbidol against influenza A virus, respiratory syncytial virus, rhinovirus, coxsackie virus and adenovirus in vitro and in vivo

Arbidol, ethyl-6-bromo-4-[(dimethylamino)-methyl]-5-hydroxy-1-methyl-2-[(phenylthio)methyl]-in dole-3-carboxylate hydrochloride monohydrate, is an antiviral chemical agent. In this report, we studied the antiviral activity of arbidol against a panel of human respiratory viruses, namely influenza A virus (FLU-A, A/PR/8/34 H1N1), respiratory syncytial virus (RSV), human rhinovirus type 14 (HRV 14), coxsackie virus B3 (CVB3) and adenovirus type 7 (AdV-7) in vitro in cell culture. Arbidol was found to present potent inhibitory activity against enveloped and non-enveloped RNA viruses, including FLU-A, RSV, HRV 14 and CVB3 when added before, during, or after viral infection, with 50% inhibitory concentration (IC50) ranging from 2.7 to 13.8 microg/ml. However, arbidol showed selective antiviral activity against AdV-7, a DNA virus, only when added after infection (therapeutic index (TI) = 5.5). Orally administered arbidol at 50 or 100 mg/kg/day beginning 24 h pre-virus exposure for 6 days significantly reduced mean pulmonary virus yields and the rate of mortality in mice infected with FLU-A (A/PR/8/34 H1N1). Our results suggest that arbidol has the ability to elicit protective broad-spectrum antiviral activity against a number of human pathogenic respiratory viruses.

Functional region IV of glycoprotein D from herpes simplex virus modulates glycoprotein binding to the herpesvirus entry mediator

Glycoprotein D (gD) of herpes simplex virus (HSV) is essential for virus entry and has four functional regions (I to IV) important for this process. We previously showed that a truncated form of a functional region IV variant, gD1(Delta290-299t), had an enhanced ability to block virus entry and to bind to the herpesvirus entry mediator (HveAt; formerly HVEMt), a cellular receptor for HSV. To explore this phenotype further, we examined other forms of gD, especially ones with mutations in region IV. Variant proteins with deletions of amino acids between 277 and 300 (region IV), as well as truncated forms lacking C-terminal residues up to amino acid 275 of gD, were able to block HSV entry into Vero cells 1 to 2 logs better than wild-type gD1(306t). In contrast, gD truncated at residue 234 did not block virus entry into Vero cells. Using optical biosensor technology, we recently showed that gD1(Delta290-299t) had a 100-fold-higher affinity for HveAt than gD1(306t) (3.3 x 10(-8) M versus 3.2 x 10(-6) M). Here we found that the affinities of other region IV variants for HveAt were similar to that of gD1(Delta290-299t). Thus, the affinity data follow the same hierarchy as the blocking data. In each case, the higher affinity was due primarily to a faster kon rather than to a slower koff. Therefore, once the gDt-HveAt complex formed, its stability was unaffected by mutations in or near region IV. gD truncated at residue 234 bound to HveAt with a lower affinity (2.0 x 10(-5) M) than did gD1(306t) due to a more rapid koff. These data suggest that residues between 234 and 275 are important for maintaining stability of the gDt-HveAt complex and that functional region IV is important for modulating the binding of gD to HveA. The binding properties of any gD1(234t)-receptor complex could account for the inability of this form of gDt to block HSV infection.

Genetic polymorphisms and other risk factors associated with bisphosphonate induced osteonecrosis of the jaw

Bisphosphonate induced osteonecrosis of the jaw (BONJ) is a complication in patients taking bisphosphonate (BP) that affects their quality of life and compliance. In this cohort study, patients with multiple myeloma (MM) on intravenous BP therapy were enrolled over 1 year. Demographic and clinical data and genotyping of 10 single nucleotide polymorphisms (SNPs) from seven candidate genes associated with drug or bone metabolism were determined. Of the 78 patients enrolled, 12 had BONJ. The median time to developing BONJ was 28 months. Univariate and multivariate analysis revealed a significant association between BONJ and smoking (p=0.048) and type of BP treatment (p=0.03). A trend for higher odds for BONJ was found for SNPs in five genes: COL1A1 (rs1800012), RANK (rs12458117), MMP2 (rs243865), OPG (rs2073618) and OPN (rs11730582). Considering all five SNPs together, patients with genotype scores ≥ 5 had a BONJ event rate of 57%; those with scores < 5 had a rate of 10%. The adjusted odds ratio was 11.2 (95% confidence interval of 1.8-69.9; p value 0.0097). Smoking, type of BP and combined genotype score of COL1A1, RANK, MMP2, OPG and OPN were significantly associated with BONJ in MM patients undergoing BP therapy.

The major neutralizing antigenic site on herpes simplex virus glycoprotein D overlaps a receptor-binding domain

Herpes simplex virus (HSV) entry is dependent on the interaction of virion glycoprotein D (gD) with one of several cellular receptors. We previously showed that gD binds specifically to two structurally dissimilar receptors, HveA and HveC. We have continued our studies by using (i) a panel of baculovirus-produced gD molecules with various C-terminal truncations and (ii) a series of gD mutants with nonoverlapping 3-amino-acid deletions between residues 222 and 254. Binding of the potent neutralizing monoclonal antibody (MAb) DL11 (group Ib) was unaffected in forms of gD containing residues 1 to 250 but was greatly diminished in molecules truncated at residue 240 or 234. Both receptor binding and blocking of HSV infection were also affected by these C-terminal truncations. gD-1(234t) bound weakly to both HveA and HveC as determined by enzyme-linked immunosorbent assay (ELISA) and failed to block infection. Interestingly, gD-1(240t) bound well to both receptors but blocked infection poorly, indicating that receptor binding as measured by ELISA is not the only gD function required for blocking. Optical biosensor studies showed that while gD-1(240t) bound HveC with an affinity similar to that of gD-1(306t), the rates of complex formation and dissociation were significantly faster than for gD-1(306t). Complementation analysis showed that any 3-amino-acid deletion between residues 222 and 251 of gD resulted in a nonfunctional protein. Among this set of proteins, three had lost DL11 reactivity (those with deletions between residues 222 and 230). One of these proteins (deletion 222-224) was expressed as a soluble form in the baculovirus system. This protein did not react with DL11, bound to both HveA and HveC poorly as shown by ELISA, and failed to block HSV infection. Since this protein was bound by several other MAbs that recognize discontinuous epitopes, we conclude that residues 222 to 224 are critical for gD function. We propose that the potent virus-neutralizing activity of DL11 (and other group Ib MAbs) likely reflects an overlap between its epitope and a receptor-binding domain of gD.

RAGE is essential for oncogenic KRAS-mediated hypoxic signaling in pancreatic cancer

A hypoxic tumor microenvironment is characteristic of many cancer types, including one of the most lethal, pancreatic cancer. We recently demonstrated that the receptor for advanced glycation end products (RAGE) has an important role in promoting the development of pancreatic cancer and attenuating the response to chemotherapy. We now demonstrate that binding of RAGE to oncogenic KRAS facilitates hypoxia-inducible factor 1 (HIF1)α activation and promotes pancreatic tumor growth under hypoxic conditions. Hypoxia induces NF-κB-dependent and HIF1α-independent RAGE expression in pancreatic tumor cells. Moreover, the interaction between RAGE and mutant KRAS increases under hypoxia, which in turn sustains KRAS signaling pathways (RAF-MEK-ERK and PI3K-AKT), facilitating stabilization and transcriptional activity of HIF1α. Knock down of RAGE in vitro inhibits KRAS signaling, promotes HIF1α degradation, and increases hypoxia-induced pancreatic tumor cell death. RAGE-deficient mice have impaired oncogenic KRAS-driven pancreatic tumor growth with significant downregulation of the HIF1α signaling pathway. Our results provide a novel mechanistic link between NF-κB, KRAS, and HIF1α, three potent molecular pathways in the cellular response to hypoxia during pancreatic tumor development and suggest alternatives for preventive and therapeutic strategies.

Hyperaccumulation of cadmium by roots, bulbs and shoots of garlic (Allium sativum L.)

The effects of cadmium chloride concentration on root, bulb and shoot growth of garlic (Allium sativum L.), and the uptake and accumulation of Cd2+ by garlic roots, bulbs and shoots were investigated. The range of cadmium chloride (CdCl2 x 2.5H2O) concentrations was 10(-6) - 10(-2) M. Cadmium stimulated root length at lower concentrations (10(-6) - 10(-5) M) significantly (P < 0.005) during the entire treatment period. The seedlings exposed to 10(-3) - 10(-2) M Cd exhibited substantial growth reduction (P < 0.005), but did not develop chlorosis. Garlic has considerable ability to remove Cd from solutions and accumulate it. The Cd content in roots of garlic increased with increasing solution concentration of Cd2+. The roots in plants exposed to 10(-2) M Cd accumulated a large amount of Cd. approximately 1,826 times the control. The Cd contents in roots of plants treated with 10(-3), 10(-4), 10(-5) and 10(-6) M Cd were approximately 114, 59, 24 and 4 times the control, respectively. However, the plants transported only a small amount of Cd to their bulbs and shoots and concentrations in these tissues were low.

LPS-induced inflammatory response after therapy of aggressive periodontitis

We have reported a lipopolysaccharide (LPS)-induced hyper-inflammatory response in localized aggressive periodontitis (LAP). It is unknown whether treatment is able to modulate this LPS responsiveness. Fifty-nine individuals with LAP were treated by mechanical debridement and systemic antibiotics. Clinical parameters and cyto/chemokine responsiveness of whole blood stimulated with Porphyromonas gingivalis or Escherichia coli LPS were monitored at baseline and 3, 6, and 12 months post-treatment. Overall, clinical parameters were improved following treatment. Additionally, P. gingivalis LPS induction of eotaxin, IFNγ, IL10, IL12p40, IL1β, IL6, IP10, MCP1, MIP1α, GM-CSF, and TNFα was significantly decreased (p < .05). Similarly, induction of eotaxin, INFγ, IL10, IL12p40, GM-CSF, and TNFα by E. coli LPS was also reduced post-treatment. These reductions correlated with decreases in clinical parameters. Importantly, these reductions in LPS responsiveness were most robust at 3 months, and some lost significance at 6 to 12 months post-treatment. In conclusion, LPS-induced hyper-inflammatory response in LAP can be partially modulated by periodontal therapy. Conversely, rebound in the hyper-responsiveness of some mediators, in the presence of improved clinical parameters, suggests that this phenotype could be partially influenced by a genetic trait and play a role in future disease recurrence (ClinicalTrials.gov, NCT01330719).

Interactions of polyomavirus middle T with the SH2 domains of the pp85 subunit of phosphatidylinositol-3-kinase

The binding of phosphatidylinositol-3-kinase to the polyomavirus middle T antigen is facilitated by tyrosine phosphorylation of middle T on residue 315. The pp85 subunit of phosphatidylinositol-3-kinase contains two SH2 domains, one in the middle of the molecule and one at the C terminus. When assayed by blotting with phosphorylated middle T, the more N-terminal SH2 domain is responsible for binding to middle T. When assayed in solution with glutathione S transferase fusions, both SH2s are capable of binding phosphorylated middle T. While both SH2 fusions can compete with intact pp85 for binding to middle T, the C-terminal SH2 is the more efficient of the two. Interaction between pp85 or its SH2 domains and middle T can be blocked by a synthetic peptide comprising the tyrosine phosphorylation sequence around middle T residue 315. Despite the fact that middle T can interact with both SH2s, these domains are not equivalent. Only the C-terminal SH2-middle T interaction was blocked by anti-SH2 antibody; the two SH2 fusions also interact with different cellular proteins.

Ability of various bombesin receptor agonists and antagonists to alter intracellular signaling of the human orphan receptor BRS-3

Bombesin (Bn) receptor subtype 3 (BRS-3) is an orphan receptor that is a predicted member of the heptahelical G-protein receptor family and so named because it shares a 50% amino acid homology with receptors for the mammalian bombesin-like peptides neuromedin B (NMB) and gastrin-releasing peptide. In a recent targeted disruption study, in which BRS-3-deficient mice were generated, the mice developed obesity, diabetes, and hypertension. To date, BRS-3's natural ligand remains unknown, its pharmacology unclear, and cellular basis of action undetermined. Furthermore, there are few tissues or cell lines found that express sufficient levels of BRS-3 protein for study. To define the intracellular signaling properties of BRS-3, we examined the ability of [D-Phe6,beta-Ala11,Phe13, Nle14]Bn-(6-14), a newly discovered peptide with high affinity for BRS-3, and various Bn receptor agonists and antagonists to alter cellular function in hBRS-3-transfected BALB 3T3 cells and hBRS-3-transfected NCI-H1299 non-small cell lung cancer cells, which natively express very low levels of hBRS-3. This ligand stimulated a 4-9-fold increase in [3H]inositol phosphate formation in both cell lines under conditions where it caused no stimulation in untransfected cells and also stimulated an increase in [3H]IP1, [3H]IP2, and 3H]IP3. The elevation of [3H]IP was concentration-dependent, with an EC50 of 20-35 nM in both cell lines. [D-Phe6,beta-Ala11,Phe13,Nle14]Bn-(6-14) stimulated a 2-3-fold increase in [Ca2+]i, a 3-fold increase in tyrosine phosphorylation of p125(FAK) with an EC50 of 0.2-0.7 nM, but failed to either stimulate increases in cyclic AMP or inhibit forskolin-stimulated increases. None of nine naturally occurring Bn peptides or three synthetic Bn analogues reported to activate hBRS-3 did so with high affinity. No high affinity Bn receptor antagonists had high affinity for the hBRS-3 receptor, although two low affinity antagonists for gastrin-releasing peptide and NMB receptors, [D-Arg1,D-Trp7,9, Leu11]substance P and [D-Pro4,D-Trp7,9,10]substance P-(4-11), inhibited hBRS-3 receptor activation. The NMB receptor-specific antagonist D-Nal,Cys,Tyr,D-Trp,Lys,Val, Cys,Nal-NH2 inhibited hBRS-3 receptor activation in a competitive fashion (Ki = 0.5 microM). Stimulation of p125(FAK) tyrosine phosphorylation by hBRS-3 activation was not inhibited by the protein kinase C inhibitor, GF109203X, or thapsigargin, alone or in combination. These results show that hBRS-3 receptor activation increases phospholipase C activity, which causes generation of inositol phosphates and changes in [Ca2+]i and is also coupled to tyrosine kinase activation, but is not coupled to adenylate cyclase activation or inhibition. hBRS-3 receptor activation results in tyrosine phosphorylation of p125(FAK), and it is not dependent on activation of either limb of the phospholipase C cascade. Although the natural ligand is not a known bombesin-related peptide, the availability of [D-Phe6,beta-Ala11, Phe13,Nle14]Bn-(6-14), which functions as a high affinity agonist in conjunction with hBRS-3-transfected cell lines and the recognition of three classes of receptor antagonists including one with affinity of 0.5 microM, should provide important tools to assist in the identification of its natural ligand, the development of more potent selective receptor antagonists and agonists, and further exploration of the signaling properties of the hBRS-3 receptor.

Rational design of a peptide agonist that interacts selectively with the orphan receptor, bombesin receptor subtype 3

The orphan receptor, bombesin (Bn) receptor subtype 3 (BRS-3), shares high homology with bombesin receptors (neuromedin B receptor (NMB-R) and gastrin-releasing peptide receptor (GRP-R)). This receptor is widely distributed in the central nervous system and gastrointestinal tract; target disruption leads to obesity, diabetes, and hypertension, however, its role in physiological and pathological processes remain unknown due to lack of selective ligands or identification of its natural ligand. We have recently discovered (Mantey, S. A., Weber, H. C., Sainz, E., Akeson, M., Ryan, R. R. Pradhan, T. K., Searles, R. P., Spindel, E. R., Battey, J. F., Coy, D. H., and Jensen, R. T. (1997) J. Biol. Chem. 272, 26062-26071) that [d-Tyr(6),beta-Ala(11),Phe(13),Nle(14)]Bn-(6-14) has high affinity for BRS-3 and using this ligand showed BRS-3 has a unique pharmacology with high affinity for no known natural Bn peptides. However, use of this ligand is limited because it has high affinity for all known Bn receptors. In the present study we have attempted to identify BRS-3 selective ligands using a strategy of rational peptide design with the substitution of conformationally restricted amino acids into the prototype ligand [d-Tyr(6),beta-Ala(11),Phe(13),Nle(14)]Bn-(6-14) or its d-Phe(6) analogue. Each of the 22 peptides synthesized had binding affinities determined for hBRS-3, hGRPR, and hNMBR, and hBRS-3 selective ligands were tested for their ability to activate phospholipase C and increase inositol phosphates ([(3)H]inositol phosphate). Using this approach we have identified a number of BRS-3 selective ligands. These ligands functioned as receptor agonists and their binding affinities were reflected in their potencies for altering [(3)H]inositol phosphate. Two peptides with an (R)- or (S)-amino-3-phenylpropionic acid substitution for beta-Ala(11) in the prototype ligand had the highest selectivity for the hBRS-3 over the mammalian Bn receptors and did not interact with receptors for other gastrointestinal hormones/neurotransmitters. Molecular modeling demonstrated these two selective BRS-3 ligands had a unique conformation of the position 11 beta-amino acid. This selectivity was of sufficient magnitude that these should be useful in explaining the role of hBRS-3 activation in obesity, glucose homeostasis, hypertension, and other physiological or pathological processes.

Activation of toll-like receptor-3 induces interferon-lambda expression in human neuronal cells

We examined the gene expression and regulation of type III human interferon (IFN), IFN-lambda, in human neuronal cells. Human neuronal cells expressed endogenous IFN-lambda1 but not IFN-lambda2/3. Upon the activation of Toll-like receptor (TLR)-3 expressed in the neuronal cells by polyriboinosinic polyribocytidylic acid (PolyI:C), both IFN-lambda1 and IFN-lambda2/3 expression was significantly induced. The activation of TLR-3 also exhibited antiviral activity against pseudotyped human immunodeficiency virus (HIV)-1 infection of the neuronal cells. Human neuronal cells also expressed functional IFN-lambda receptor complex, interleukin-28 receptor alpha subunit (IL-28Ralpha) and IL-10Rbeta, as evidenced by the observations that exogenous IFN-lambda treatment inhibited pseudotyped HIV-1 infection of the neuronal cells and induced the expression of apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like (APOBEC)3G/3F, the newly identified anti-HIV-1 cellular factors. These data provide direct and compelling evidence that there is intracellular expression and regulation of IFN-lambda in human neuronal cells, which may have an important role in the innate neuronal protection against viral infections in the CNS.