Pan-tissue scaling of stiffness versus fibrillar collagen reflects contractility-driven strain that inhibits fibril degradation

Polymer network properties such as stiffness often exhibit characteristic power laws in polymer density and other parameters. However, it remains unclear whether diverse animal tissues, composed of many distinct polymers, exhibit such scaling. Here, we examined many diverse tissues from adult mouse and embryonic chick to determine if stiffness ( E tissue ) follows a power law in relation to the most abundant animal protein, Collagen-I, even with molecular perturbations. We quantified fibrillar collagen in intact tissue by second harmonic generation (SHG) imaging and from tissue extracts by mass spectrometry (MS), and collagenase-mediated decreases were also tracked. Pan-tissue power laws for tissue stiffness versus Collagen-I levels measured by SHG or MS exhibit sub-linear scaling that aligns with results from cellularized gels of Collagen-I but not acellular gels. Inhibition of cellular myosin-II based contraction fits the scaling, and combination with inhibitors of matrix metalloproteinases (MMPs) show collagenase activity is strain - not stress- suppressed in tissues, consistent with past studies of gels and fibrils. Beating embryonic hearts and tendons, which differ in both collagen levels and stiffness by >1000-fold, similarly suppressed collagenases at physiological strains of ∼5%, with fiber-orientation regulating degradation. Scaling of E tissue based on 'use-it-or-lose-it' kinetics provides insight into scaling of organ size, microgravity effects, and regeneration processes while suggesting contractility-driven therapeutics.

A comparative study of transdiscal versus transaortic celiac plexus neurolytic block for upper gastrointestinal cancer patients. A prospective, randomized control study

Aim: To compare transdiscal and transaortic techniques of neurolytic celiac plexus block for upper gastrointestinal cancer patients. Methods: In this prospective randomized study 60 patients with upper gastrointestinal malignancies were included and randomly divided into two groups, group TD and group TA, receiving neurolytic celiac plexus blocks via transdiscal and transaortic techniques, respectively. The primary outcome was quality of life (QoL) as assessed by WHOQOL BREF questionnaire and secondary outcomes were pain relief using visual analogue scale (VAS), and occurrence of complications like hypotension, loose motion, bleeding and discitis. Result: QoL and VAS score were significantly improved in both groups post procedure. Transdiscal approach is more effective in improving VAS score than transaortic approach (1 vs 3) after 1 week and the relief of pain was better in TD group (3 vs 6) at the end of 2 months. Transdiscal approach was found to be more effective in improving QoL (227.00±28.85 vs 191.17±35.78) as compared to transaortic approach. However, post-procedural QoL improved in both groups when compared to pre-procedural QoL (p<0.05). Hypotension, diarrhea and bleeding from aorta were higher in TA group; however, no serious complications were seen in any of the groups. Conclusion: Transdiscal technique is better in terms of adequate pain relief and improving QoL as compared to transaortic technique of NCPB in patients of upper GI malignancies and is associated with lesser incidences of complications.

Analysis of wedge resection of gallbladder bed and lymphadenectomy on adequate oncologic clearance for gallbladder cancer

BACKGROUND

Surgery (R0 resection) is the mainstay of treatment of gallbladder cancer (GBC) as GBC is relatively resistant to currently known chemotherapy and radiotherapy regimens.

AIM

to assess if wedge resection of the gallbladder bed achieves an adequate oncological clearance in GBC (namely T1 and T2) and some T3 GBC with minimal liver infiltration.

PATIENTS AND METHODS

Patients with GBC who underwent radical cholecystectomy (en bloc cholecystectomy, wedge resection of the gallbladder fossa with a ≥2 cm rim of nonneoplastic liver tissue, and regional lymph node dissection) between October 2012 and June 2015 after obtaining informed consent.

RESULTS

Of thirty patients, mean age of 52 years, 5 had T1b, 13 T2, and 12 T3 GBC. R0 resection was achieved in all thirty GBC patients. Hepatic invasion was found in seven patients. The depth of hepatic invasion ranged from 0 to 9 mm. Follow-up ranged from a minimum of 12 to 43 months. Nineteen (63%) patients had N0 and 11 (37%) had N1 GBC. Total lymph node (TLND) count ranged from 1 to 12/patient with a median of 3. There was no local recurrence or systemic relapse of the disease.

CONCLUSION

Wedge resection of the gallbladder bed achieves an adequate oncological clearance in early GBC. TLND counts remain poor even after a thorough standard lymph node dissection for resectable GBC.

Collaborating to Compete: Blood Profiling Atlas in Cancer (BloodPAC) Consortium

The cancer community understands the value of blood profiling measurements in assessing and monitoring cancer. We describe an effort among academic, government, biotechnology, diagnostic, and pharmaceutical companies called the Blood Profiling Atlas in Cancer (BloodPAC) Project. BloodPAC will aggregate, make freely available, and harmonize for further analyses, raw datasets, relevant associated clinical data (e.g., clinical diagnosis, treatment history, and outcomes), and sample preparation and handling protocols to accelerate the development of blood profiling assays.

Free radicals hasten head and neck cancer risk: A study of total oxidant, total antioxidant, DNA damage, and histological grade

Background:

Free radicals such as reactive oxygen species (ROS), which induce oxidative stress, are the main contributors to head and neck carcinogenesis (HNC). The present study was conducted with the aim to assess the oxidant/antioxidant status and DNA damage analysis in head and neck cancer/control patients.

Materials and Methods:

This prospective study was conducted on 60 patients with biopsy-proven HNC and 17 patients of head and neck disease (HND). The total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) were determined by novel automatic colorimetric methods from tissue homogenate. DNA damage analysis was determined by single cell gel electrophoresis (SCGE).

Results:

The mean age of the study cohort was 46.65 ± 14.84 years for HNC patients, while it was 49.41 ± 13.00 years for HND patients. There were no significant differences found between the two groups with respect to demographic presentation except tobacco addiction. The association between oxidative stress parameters and DNA damage analysis with study group revealed the following. (A) DNA damage - tissue homogenate TOS and OSI were significantly higher in HNC subjects than in HND (16.06 ± 1.78 AU vs 7.86 ± 5.97 AU, P < 0.001; 53.00 ± 40.61 vs 19.67 ± 21.90, P < 0.01; 7.221 ± 5.80 vs 2.40 ± 2.54, P < 0.01, respectively), while TAS was significantly decreased. (B) Aggressive histological features were identified, more commonly with higher TOS and lower TAS [probability (P) = 0.002, relative risk (RR) = 11.838, 95% confidence interval CI = 2.514-55.730 and P = 0.043, RR = 0.271, 95% CI = 0.077-0.960, respectively].

Conclusion:

The increase in free radicals may be the event that led to the reduction of antioxidant status in HNC, thus explaining the oxidative damage of DNA and the severity of disease. Increased OSI represents a general mechanism in its pathogenesis.

Advanced stage of breast cancer hoist alkaline phosphatase activity: risk factor for females in India

Breast cancer is the most common neoplasm affecting women in the western world with an average frequency of 1 in 11, developing the malignancy and it is second most common cancer in India. Variations in serum levels of biochemical parameters especially alkaline phosphatase (ALP) changes may be of great help in diagnosis of breast carcinoma. Serum ALP activity was assayed in 388 histopathologically proven breast cancer patients using spectrophotometric methods and monitored association with cancer stages. Breast cancer is a female-biased disease and our study was conducted in a group of female patients with mean age of 48.67 ± 8.32 years. A significant increase in levels of ALP (809.65 ± 145.97 IU/L) was observed in stage IV of the disease. The logistic regression study gave a significant result (P < 0.001) when we compared the group of ALP level (>500 IU/L) with metastatic presentation. The present study besides being cost effective suggested the usefulness of ALP in differentiating breast cancer stages and metastasis.

Prospects of nano-material in breast cancer management

Breast cancer evaluation and early diagnosis are core complexity worldwide and an ambiguity for scientists till date. Nano-materials are innovative tools for rapid diagnosis and therapy, which may induce an immense result in the field of oncology. Their exceptional size-dependent properties make them special and superior materials and quite indispensable in several fields of the human activities. The major obstacle in finding cure for malignant breast cancer is to increase in development of resistances for tumors to the therapeutic treatments. The widespread mammo-graph particle is being developed by nations to diagnosis disease in primitive stage to decline the mortality rates caused by breast carcinoma. The advancement of nano-particle based diagnostic tools facilitates in evaluation and provides encouraging development in breast cancer therapeutics. In this compact review, efforts have been made to compose the current advancements in the area of functional nano-particles. Furthermore, in vivo and in vitro applications of nano-materials in breast cancer management are also discussed.

Tobacco addiction augments obesity and carcinogenesis: Matter of concern for Indian patients

Purpose:

Patients and Methods:

Results:

Conclusion:

A peptide derived from hepatitis C virus E2 envelope protein inhibits a post-binding step in HCV entry

The HCV envelope proteins E1 and E2 are required for virus binding to cellular receptors and pH-dependent fusion with endosomal membranes. Envelope protein interactions within this multistep process may provide novel targets for development of antiviral agents. To identify E1 and E2 regions involved in critical steps of HCV entry, we screened an E1E2 overlapping peptide library for inhibition of infection using a lentiviral reporter vector pseudotyped with E1E2 envelope proteins. A 16-residue polypeptide containing a portion of the E2 transmembrane domain (Peptide 75) inhibited HCV pseudoparticle infection with an IC50 of approximately 0.3microM and did not inhibit infection by VSV-g pseudoparticles at concentrations up to 50microM. Structure-activity analysis of Peptide 75 showed that antiviral activity was dependent upon L-configuration and hydrophobic character, and that the native sequence was required for maximal activity. Peptide 75 did not show virocidal activity against HCV pseudoparticles or other viruses. Temperature-shift experiments showed that the peptide acted at a post-binding step and that inhibition was further increased when used in combination with an anti-CD81 antibody previously shown to inhibit pseudoparticle entry at a post-binding step. These data suggest that interactions involving the C terminal region of E2 may play an important role in the HCV entry process.

Quality assessment and data analysis for microRNA expression arrays

MicroRNAs are small (approximately 22 nt) RNAs that regulate gene expression and play important roles in both normal and disease physiology. The use of microarrays for global characterization of microRNA expression is becoming increasingly popular and has the potential to be a widely used and valuable research tool. However, microarray profiling of microRNA expression raises a number of data analytic challenges that must be addressed in order to obtain reliable results. We introduce here a universal reference microRNA reagent set as well as a series of nonhuman spiked-in synthetic microRNA controls, and demonstrate their use for quality control and between-array normalization of microRNA expression data. We also introduce diagnostic plots designed to assess and compare various normalization methods. We anticipate that the reagents and analytic approach presented here will be useful for improving the reliability of microRNA microarray experiments.

The frequency of live bacteria in gallstones

BACKGROUND

Septic complications reported from stones and concretions lost in the peritoneal cavity following laparoscopic cholecystectomy reflect the infective potential of gallstones. Although bacteria have been demonstrated in the core of gallstones by scanning electron microscopy and molecular genetic techniques, gallstone culture is the only conclusive proof of whether such bacteria are viable and can cause infection.

METHODS

Gallstones retrieved from patients undergoing cholecystectomy were decontaminated after surface cleaning with alcohol, and each core was scooped for culture.

RESULTS

In this study organisms were cultured from the cores of gallstones in 81% of cases of cholelithiasis and 77% of cases of gallbladder carcinoma, irrespective of stone type and size. Both enteric (57.5%) and non-enteric (20%) organisms were isolated in cholelithiasis, whereas only enteric bacteria could be cultured from cases of gallbladder carcinoma. Long thought to be a causative agent, Salmonella organisms were detected in none of the 14 cases of gallbladder carcinoma.

CONCLUSION

Contrary to the popular belief that bacteria inside gallstones are dead, gallstones from most patients contain live bacteria with the potential to cause infective complications.

Regulation of IL-1-induced gingival collagenase gene expression by activator protein-1 (c-Fos/c-Jun)

Matrix metalloproteinase-1 is probably involved in the progression of periodontal disease. The aim of this study was to investigate whether IL-1beta stimulates the expression of the activator protein 1 (AP-1) transcription factor and, consequently, if the AP-1 transcription factor participates in the regulation of collagenase gene expression in human gingival fibroblast cells. In this study, we demonstrate that the concentration of the protein components of AP-1 transcription factor, c-Fos and c-Jun, is enhanced by IL-1beta both at mRNA and protein levels, utilizing Northern blot analysis, electrophoretic mobility gel shift assay and Western blot analysis. The IL-1beta stimulated the collagenase-CAT and AP-1-CAT activities in a dose dependent manner with respect to the amount of DNA used in transfections. Further, overexpression of c-Fos and c-Jun proteins revealed a dose-dependent transcriptional activation of the collagenase promoter. These findings, coupled with the existence of AP-1 consensus DNA binding sites on the collagenase gene promoter, show that regulation of collagenase gene expression by IL-1beta involves the transcription factor AP-1 in gingival fibroblasts.

Human skeletal myosin heavy chain genes are tightly linked in the order embryonic-IIa-IId/x-ILb-perinatal-extraocular

Myosin heavy chain (MyHC) is the major contractile protein of muscle. We report the first complete cosmid cloning and definitive physical map of the tandemly linked human skeletal MyHC genes at 17p13.1. The map provides new information on the order, size, and relative spacing of the genes. and it resolves uncertainties about the two fastest twitch isoforms. The physical order of the genes is demonstrated to contrast with the temporal order of their developmental expression. Furthermore, nucleotide sequence comparisons allow an approximation of the relative timing of five ancestral duplications that created distinct genes for the six isoforms. A firm foundation is provided for molecular analysis in patients with suspected primary skeletal myosinopathies and for detailed modelling of the hypervariable surface loops which dictate myosin's kinetic properties.

Antizyme prevents ornithine decarboxylase-mediated cell death in human fibroblasts

Ornithine decarboxylase (ODC) is a key enzyme of polyamine biosynthesis essential for growth-related cellular functions. Apart from its physiological role in cell proliferation, ODC also contributes to the induction of apoptosis under certain conditions, e.g. following growth factor withdrawal. The rate of cell death is a function of its enzyme activity, ODC activity is inhibited by a regulatory protein antizyme, also known to suppress polyamine uptake. We report that forced expression of antizyme prevents ODC-mediated cell death in human gingival fibroblasts under very low serum conditions. These data suggest an important antiapoptotic role for antizyme in cell survival.

Inhibition of gingival collagenase gene expression by dexamethasone

Glucocorticoids are potent immunosuppressants shown to be effective in the treatment of inflammatory diseases. Reportedly, they work, in part, by inhibiting cytokines and other transcription factors including AP-1. In this study we investigated the mechanisms of efficient repression of collagenase gene expression by dexamethasone in the human gingival fibroblast. Northern analyses showed that IL-1-dependent collagenase mRNA production was significantly decreased in the presence of dexamethasone. The influence of dexamethasone on the transcription factor NF-kappaB, STAT3, and AP-1 was investigated by using the gel mobility shift assay with nuclear extracts prepared from the cells grown in the presence of dexamethasone. We observed that in addition to AP-1, binding of NF-kappaB and STAT3 to DNA was also decreased significantly. Additionally, dexamethasone induced the transcription of the I kappaB-alpha gene suggesting that in the presence of dexamethasone, NF-kappaB quickly reassociates with newly synthesized I kappaB-alpha and markedly reduces the amount of NF-kappaB. CAT transfection studies utilizing collagenase promoter demonstrated a dose-dependent transcriptional inhibition of IL-1-induced gingival collagenase gene expression by dexamethasone. These data reveal that collagenase gene expression can be regulated by the impairment of IL-1-stimulated NF-kappaB, STAT3, and AP-1 activities, and can highlight a possible molecular mechanism for the anti-inflammatory effects of glucocorticoids.

A study on transferable R-plasmids among Shigella species at Lucknow

A total of 500 Shigella strains were included in the present study out of which 233 were isolated at National Shigella Centre of Postgraduate Department of Microbiology, K.G. Medical College, Lucknow during last 5 years and 267 strains were received from different parts of the country. Predominent serotypes were Sheigella flexneri 292 (48.4%) followed by Shigella dysenteriae 153 (30.6%), Shigella boydii 32 (6.4%) and Shigella sonnei 23 (4.6%). All the strains were sensitive to Nalidix acid, Gentamycin, Kanamycin, Neomycin and Furazolidine. Varying degree of resistance was shown to Streptomycin, Chloramphenicol, Tetracycline and Ampicillin. R. plasmid extraction was done and transfer was studied on E. Coli K-12.

AAC-11, a novel cDNA that inhibits apoptosis after growth factor withdrawal

Many growth factors and cytokines act as cellular survival factors by preventing programmed cell death (apoptosis). However, the specific genes and corresponding proteins that mediate survival are poorly defined. To identify potential survival genes, a cDNA library was prepared from murine fibroblasts and screened by a functional expression cloning approach. A 1023-bp cDNA, AAC-11, was identified that encodes a protein of approximately 25 kDa. The AAC-11 gene shows strong species conservation and is ubiquitously expressed in embryonic and adult tissues with multiple transcripts, as well as in various human tumor cell lines. The predicted protein contains a leucine zipper domain but lacks a DNA-binding domain. BALB/c3T3 fibroblasts that were stably transfected with AAC-11 cDNA were viable in serum-free medium for up to 12 weeks. The protective action of AAC-11 was abolished by mutation of leucines to arginines within the leucine zipper domain. We also isolated a longer AAC-11 cDNA that codes for up to an additional 290 amino-terminal amino acids but did not protect against apoptosis. The cDNA for human AAC-11 was identified and exhibits strong homology with the murine species and retains the leucine zipper domain. Western immunoblots of BALB/c3T3 cells using rabbit anti-AAC-11 polyclonal serum revealed a major native 55-kDa AAC-11 protein and a minor 25-kDa protein corresponding to the long and short forms of AAC-11 cDNA, respectively. In summary, we report a cDNA whose expression supports cell viability after withdrawal of growth factors. The corresponding native protein may function as a novel inhibitor of apoptosis.

Ethanol promotes cell death by inhibition of the insulin-like growth factor I receptor

The mechanism by which chronic alcohol abuse induces widespread cell and tissue damage is unknown. Insulin-like growth factor I (IGF-I) is an important inhibitor of apoptosis in many cell types, in addition to its ability to stimulate proliferation. We have demonstrated previously (J. Biol. Chem. 268:21777-21782, 1993; Lab. Invest. 71:657-662, 1994) that ethanol in low concentrations inhibits the tyrosine autophosphorylation of the IGF-I receptor (IGF-IR) and IGF-I-mediated cell proliferation. We now demonstrate that ethanol reverses the antiapoptotic action of the IGF-IR in a tumor necrosis factor-alpha (TNF-alpha) model of apoptosis. In serum-depleted medium, IGF-I markedly protected BALB/c3T3 cells from TNF-alpha-induced apoptosis. Ethanol reversed the protective action of IGF-I, but did not enhance TNF-alpha killing in the absence of IGF-I. Half-maximal effective concentrations of ethanol were 5 to 10 mM. In the presence of 5 to 10% fetal bovine serum, TNF-alpha was cytotoxic for 3T3 cells only in the presence of ethanol. Mouse embryo fibroblasts with targeted knockout of the IGF-IR were completely insensitive to ethanol, in contrast with the ethanol-induced potentiation of apoptosis in wild-type cells. These results indicate that ethanol directly interacts with cellular factors that inhibit apoptosis and could provide a novel mechanism for ethanol-induced cytotoxicity in general.

The myosin filament XV assembly: contributions of 195 residue segments of the myosin rod and the eight C-terminal residues

A mixture of two peptides of approximately M(r) 13000 has been isolated from a papain digest of LC2 deficient myosin. The peptides assemble into highly ordered aggregates which in one view are made up of strands of pairs of dots with an average side to side spacing of 13.0 nm and an average axial repeat of 9.0 nm. In another view there are strands of single dots with a side-to-side spacing of 7.8 nm and an axial repeat of 9.1 nm. From N-terminal peptide sequencing, the two peptides have been shown to come from regions of the myosin rod displaced by 195 residues. We have shown that either peptide alone can assemble to form the same aggregates. The 195 residue displacement of the M(r) 13000 peptides corresponds closely to the 196 residue repeat of charges along the myosin rod. This finding permits us to designate 195 residue segments of the myosin rod and to relate assembly characteristics directly to the similar 195 residue segments and 196 residue charge repeat. The most C-terminal 195 residue segment carries information for assembly into helical strands. The contiguous 195 residue segment, in major part, carries information for the unipolar assembly, characteristic of the assembly in each half of the myosin filament. The next contiguous 195 residue segment, in major part, carries information for bipolar assembly which is characteristic of the bare zone region of the filament; and for the transition from the bipolar bare zone to unipolar assembly. The effect of the eight C-terminal residues of the myosin rod on the assembly of the contiguous 195 residues has also been studied. The entire fragment of 195 + eight C-terminal residues assembled to form helical strands with an axial repeat of 30 nm. Successive deletion of charged residues changed the axial repeat of the helical strands suggesting that the charged residues at the C-terminus are involved in determining the pitch in the helical assembly of the contiguous 195 residues.

Activation of the insulin-like growth factor-I receptor inhibits tumor necrosis factor-induced cell death

The effect of insulin-like growth factor (IGF) on tumor necrosis factor (TNF)-induced cell killing was determined for mouse BALB/c3T3 fibroblasts in vitro. Cells maintained in 0.5% fetal bovine serum (FBS) were killed by TNF within 6 h in a concentration-dependent manner, an effect that was prevented by IGF-I. TNF-induced cytotoxicity of 3T3 cells that overexpress the human IGF-I receptor (p6 cells) was prevented by IGF-I alone in the absence of serum. TNF-induced cell death was associated with the morphologic features of apoptosis and the release of low-molecular-weight DNA, both of which were prevented by IGF-I. Neither epidermal growth factor (EGF) nor platelet-derived growth factor (PDGF) protected p6 cells from TNF-induced apoptosis. The specific protective action of the IGF-I receptor was demonstrated further by the marked sensitivity to TNF of embryo fibroblasts derived from mice with targeted disruption of the IGF-I receptor (R-cells) but not of fibroblasts derived from wild-type littermates or R-cells transfected with the cDNA for the human IGF-I receptor. Cycloheximide or actinomycin D markedly reduced the protection offered by IGF-I. IGF-I protection of BALB/c3T3 cells persisted for up to 5 days in the presence of PDGF and EGF, whereas IGF-I lost its effectiveness after 2 days in the absence of growth factors. IGF-I did not prevent TNF-induced release of arachidonic acid. The results demonstrate a specific role for the IGF-I receptor in the protection against TNF cytotoxicity. This action of the IGF-I receptor is mediated by protective cytosolic proteins that exhibit a high rate of turnover and whose levels are regulated principally by factors within serum other than IGF-I.

Recalcitrant gross hematuria secondary to left renal vein hypertension

Left renal vein hypertension is a most uncommon and rarely a well-documented cause of gross hematuria. We report a case of lateralizing, gross hematuria resulting from left renal vein hypertension in an individual with a history of a prior Whipple procedure. The diagnosis was suspected at the time of renal angiography and proven by renal venography. Complete rapid resolution of the hematuria and hypertension was achieved following placement of a left renal vein stent.

Association of interleukin-1-induced, NF kappa B DNA-binding activity with collagenase gene expression in human gingival fibroblasts

During earlier examination of interleukin-1 (IL-1)-induced matrix metalloproteinase gene expression in human gingival fibroblasts a highly induced immediate early gene, I kappa B-alpha, a NF kappa B DNA-binding inhibitor, was identified. The aim now was to investigate whether recombinant (r)IL-1 beta induces the stimulation of NF kappa B and its inhibitor proteins in human gingival fibroblasts and to understand if inhibition of its activity affects collagenase gene expression. Primary gingival fibroblasts (human) were treated with rIL-1 beta to determine the effect on NF kappa B-like DNA-binding activity. IL-1 induced the production of steady-state mRNA levels of I kappa B-alpha in the cultured fibroblasts. Nuclear run-on transcription studies demonstrated that rIL-1 induction of I kappa B-alpha may be transcriptionally regulated. Using electrophoretic mobility gel-shift assays it was shown that rIL-1 activates NF kappa B-like, DNA-binding activity in these fibroblasts. NF kappa B-like DNA-binding activity was rapidly induced and turned over in gingival fibroblasts with peak activity at 30 min after rIL-1 treatment. Further, treatment with chymotrypsin protease inhibitor and antioxidant inhibitor prevented IL-1-induced, NF kappa B-like, DNA-binding activity and collagenase mRNA production. When coupled with the existence of NF kappa B consensus DNA-binding sites on the collagenase gene promoter, these findings suggest that the stimulation of NF kappa B in gingival fibroblasts by rIL-1 could play an important part in the regulation of their collagenase gene expression. The ability of IL-1 to stimulate this expression may define a pivotal role for this cytokine in the pathogenesis of periodontitis.

Proteolytic activation of the cell death protease Yama/CPP32 by granzyme B

The serine protease granzyme B, which is secreted by cytotoxic cells, is one of the major effectors of apoptosis in susceptible targets. To examine the apoptotic mechanism of granzyme B, we have analyzed its effect on purified proteins that are thought to be components of death pathways inherent to cells. We demonstrate that granzyme B processes interleukin 1beta-converting enzyme (ICE) and the ICE-related protease Yama (also known as CPP32 or apopain) by limited proteolysis. Processing of ICE does not lead to activation. However, processing by granzyme B leads directly to the activation of Yama, which is now able to bind inhibitors and cleave the substrate poly(ADP-ribose) polymerase whose proteolysis is a marker of apoptosis initiated by several other stimuli. Thus ICE-related proteases can be activated by serine proteases that possess the correct specificity. Activation of pro-Yama by granzyme B is within the physiologic range. Thus the cytotoxic effect of granzyme B can be explained by its activation of an endogenous protease component of a programmed cell death pathway.

Recent advances in tumor necrosis factor and CD40 signaling

The past year has witnessed remarkable advances in the understanding of signaling by the two TNF (tumor necrosis factor) receptors, TNFR1 and TNFR2, and the related CD40 receptor. Adaptor molecules (termed TRAFs) have been identified that associate with TNFR2 and CD40 and function to modulate the signaling pathways. Significantly, TRAF2 mediates the activation of NF-kappa B by both receptors. Furthermore, a molecule called TRADD has been identified that associates with the cytoplasmic segment of TNFR1. TRADD, which contains a novel 'death domain' that binds to the corresponding death domain in the cytoplasmic segment of TNFR1, can mediate both activation of NF-kappa B and induction of apoptosis, the two major responses signaled by TNFR1.

CrmA, a poxvirus-encoded serpin, inhibits cytotoxic T-lymphocyte-mediated apoptosis

Cytotoxic T-lymphocytes (CTLs), by virtue of their ability to recognize and induce apoptotic death of virus-infected cells, comprise a major antiviral defense mechanism. The induction of apoptosis by CTLs can be completely accounted for by two mechanisms: (i) a Ca(2+)-dependent component that involves the exocytotic release of serine proteases known as granzymes from CTL granules and their subsequent insertion into the target cell to induce apoptosis and (ii) a Ca(2+)-independent component that involves the activation of Fas, a receptor on the target cell membrane that triggers apoptosis. Although viruses have evolved several indirect mechanisms for evading the CTL response, direct inhibition of the apoptotic cascade has never been described. We now show for the first time that the cowpox virus protein CrmA, a protease inhibitor of the serpin family, is capable of inhibiting CTL-mediated cytolysis. The inhibitory effect is largely the result of blockade of the Ca(2+)-independent (i.e. Fas-mediated) component of CTL killing. CrmA thus represents the first example of a viral gene product capable of directly blocking CTL-mediated cell death.

CrmA-inhibitable cleavage of the 70-kDa protein component of the U1 small nuclear ribonucleoprotein during Fas- and tumor necrosis factor-induced apoptosis

Fas and the type I tumor necrosis factor receptor (TNF-R) are two cell surface receptors that, when stimulated with ligand or cross-linking antibody, trigger apoptotic cell death by a mechanism that has yet to be elucidated. The CrmA protein is a serpin family protease inhibitor than can inhibit interleukin-1 beta converting enzyme (ICE) and ICE-like proteases. We showed previously that expression of CrmA potently blocks apoptosis induced by activation of either Fas or TNF-R, implicating protease involvement in these death pathways (Tewari, M., and Dixit, V.M. (1995) J. Biol. Chem. 270, 3255-3260). Here we report that the 70-kDa component of the U1 small ribonucleoprotein (U1-70 kDa) is a proteolytic substrate rapidly cleaved during both Fas- and TNF-R-induced apoptosis. This cleavage was inhibited by expression of CrmA, but not by expression of an inactive point mutant of CrmA, confirming the involvement of an ICE-like protease. These data for the first time identify U1-70 kDa as a death substrate cleaved during Fas- and TNF-R-induced apoptosis and emphasize the importance of protease activation in the cell death pathway.

The baculovirus p35 protein inhibits Fas- and tumor necrosis factor-induced apoptosis

The baculovirus p35 gene product inhibits virally induced apoptosis, developmental cell death in Caenorhabditis elegans and Drosophila, and neuronal cell death in mammalian systems. Therefore, p35 likely inhibits a component of the death machinery that is both ubiquitous and highly conserved in evolution. We now show for the first time that p35 also inhibits Fas- and tumor necrosis factor (TNF)-induced apoptosis. Additionally, p35 blocks TNF- and Fas-induced proteolytic cleavage of the death substrate poly(ADP-ribose) polymerase from its native 116-kDa form to the characteristic 85-kDa form. This cleavage is thought to be catalyzed by an aspartate-specific protease of the interleukin 1 beta-converting enzyme family designated prICE (Lazebnik, Y. A., Kaufmann, S. H., Desnoyers, S., Poirier, G. G., and Earnshaw, W. C. (1994) Nature 371, 346-347). Our data suggest that p35 must directly or indirectly inhibit prICE. Given that p35 inhibits both TNF and Fas killing, along with previous reports of its ability to block developmental, viral, and x-irradiation-induced cell death, the present results indicate that TNF- and Fas-mediated apoptotic pathways must have components in common with these highly conserved death programs.

Bcl-x and Bcl-2 inhibit TNF and Fas-induced apoptosis and activation of phospholipase A2 in breast carcinoma cells

Tumor necrosis factor (TNF) induces cel death in several tumor cell lines by undefined mechanisms. Using a cDNA expression cloning strategy we identified two cDNAs that completely inhibit the TNF-induced death pathway in MCF7 breast carcinoma cells. These cDNAs encoded for Bcl-2 and Bcl-x. To compare the cytotoxic signal transduction pathway induced by the TNF receptor versus that induced by Fas, we transfected MCF7 cells with a Fas expression construct. The resulting cell line, MCF-Fas, was highly sensitive to cytotoxicity induced by TNF or anti-Fas. Expression of either bcl-2 or bcl-x in these cells rendered them completely resistant to lysis induced by either TNF or Fas. Interestingly, exposure of MCF-Fas cells to anti-Fas or TNF induced activation of phospholipase A2 (PLA2), while only TNF activated NF-kappa B. Activation of PLA2 was completely blocked whereas activation of NF-kappa B was unaffected by overexpression of either bcl-x or bcl-2. Moreover, PLA2-inhibitors, quinacrine and dexamethasone, partially inhibited cytotoxicity induced by either TNF or anti-Fas. These data suggest an involvement of PLA2 in both TNF- and Fas-mediated cytotoxicity and a novel mechanism of action for bcl-2 and bcl-x, i.e. inhibition of arachidonic acid metabolism, by which they may, in addition of apoptosis, modulate inflammation.

Yama/CPP32 beta, a mammalian homolog of CED-3, is a CrmA-inhibitable protease that cleaves the death substrate poly(ADP-ribose) polymerase

Although the mechanism of mammalian apoptosis has not been elucidated, a protease of the CED-3/ICE family is anticipated to be a component of the death machinery. Several lines of evidence predict that this protease cleaves the death substrate poly(ADP-ribose) polymerase (PARP) to a specific 85 kDa form observed during apoptosis, is inhibitable by the CrmA protein, and is distinct from ICE. We cloned a ced-3/ICE-related gene, designated Yama, that encodes a protein identical to CPP32 beta. Purified Yama was a zymogen that, when activated, cleaved PARP to generate the 85 kDa apoptotic fragment. Cleavage of PARP by Yama was inhibited by CrmA but not by an inactive point mutant of CrmA. Furthermore, CrmA blocked cleavage of PARP in cells undergoing apoptosis. We propose that Yama may represent an effector component of the mammalian cell death pathway and suggest that CrmA blocks apoptosis by inhibiting Yama.

Activation of the B-cell surface receptor CD40 induces A20, a novel zinc finger protein that inhibits apoptosis

CD40 activation is critical for B-cell function, leading to activation and expression of cell surface markers, proliferation, immunoglobulin class switching and inhibition of programmed cell death (PCD). Germinal center B-cells, for example, can be prevented from undergoing PCD by CD40 activation. The mechanism by which PCD is inhibited has been an enigma. A potential role for A20, a novel zinc finger protein, in inhibiting B-cell apoptosis was suggested by our previous finding that it is induced by the Epstein-Barr virus LMP-1 gene product, a potent cell death inhibitor. We now show that CD40 activation induces A20 and that expression of A20 renders B-cell lines resistant to PCD. Additionally, we show that CD40 activation of A20 expression is mediated by inducible binding of NF-kappa B complexes to the A20 promoter and provide evidence for a critical role for Thr234 (in the CD40 cytoplasmic domain) in activating NF-kappa B.

FADD, a novel death domain-containing protein, interacts with the death domain of Fas and initiates apoptosis

Using the cytoplasmic domain of Fas in the yeast two-hybrid system, we have identified a novel interacting protein, FADD, which binds Fas and Fas-FD5, a mutant of Fas possessing enhanced killing activity, but not the functionally inactive mutants Fas-LPR and Fas-FD8. FADD contains a death domain homologous to the death domains of Fas and TNFR-1. A point mutation in FADD, analogous to the lpr mutation of Fas, abolishes its ability to bind Fas, suggesting a death domain to death domain interaction. Overexpression of FADD in MCF7 and BJAB cells induces apoptosis, which, like Fas-induced apoptosis, is blocked by CrmA, a specific inhibitor of the interleukin-1 beta-converting enzyme. These findings suggest that FADD may play an important role in the proximal signal transduction of Fas.