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A basic assumption of the study of central nervous system (CNS)-immune interactions is that the immune system can signal the brain and that the brain can subsequently modify peripheral immune function. The existence of a regulatory pathway from the immune system to the CNS and back to the immune system suggests that the phenomena of conditioning of immune responses may be explained through the action of classical immunoregulatory lymphokines such as IL-1 on humoral and neural regulatory pathways. Bi-directional communication between the central nervous system and the immune system was first proposed by Besedovsky and colleagues. In their model, products of the immune system released from stimulated immune cells signal the brain which consequently induced a response that down-regulated immune function. The impact of CNS signalling on various components of the immune system has been demonstrated through various behavioral conditioning studies.

Many cell death pathways converge at the mitochondria to induce release of apoptogenic proteins and permeability transition, resulting in the activation of effector caspases responsible for the biochemical and morphological alterations of apoptosis. The death receptor pathway has been described as a triphasic process initiated by the activation of apical caspases, a mitochondrial phase, and then the final phase of effector caspase activation. Granzyme B (GrB) activates apical and effector caspases as well as promotes cytochrome c (cyt c) release and loss of mitochondrial membrane potential. We investigated how GrB affects mitochondria utilizing an in vitro cell-free system and determined that cyt c release and permeability transition are initiated by distinct mechanisms. The cleavage of cytosolic BID by GrB results in truncated BID, initiating mitochondrial cyt c release. BID is the sole cytosolic protein responsible for this phenomenon in vitro, yet caspases were found to participate in cyt c release in some cells. On the other hand, GrB acts directly on mitochondria in the absence of cytosolic S100 proteins to open the permeability transition pore and to disrupt the proton electrochemical gradient. We suggest that GrB acts by two distinct mechanisms on mitochondria that ultimately lead to mitochondrial dysfunction and cellular demise.

The mechanisms mediating the effects of stress on immune function have yet to be fully described. In vitro studies have demonstrated a role for both the sympathetic nervous system (SNS) and the hypothalamic pituitary adrenal axis (HPAA) in regulating immune responses following exposure to various stressors. The purpose of the present set of experiments was to determine the in vivo contribution of the HPAA and SNS in regulating the effects of stress on lipopolysaccharide (LPS) induced splenic cytokine production. For this, rats with combinations of sham surgeries, splenic nerve cuts (SNC), and adrenalectomies (ADX) were exposed to 15 min of 1.6 mA intermittent footshock immediately following the intravenous (i.v.) injection of 0.1 microg of LPS. Although footshock was immunosuppressive to most indices of cytokine production, neither SNC nor ADX alone blocked the effects of stress on splenic immune function. However the combination of these two manipulations significantly abrogated the immunosuppressive effects of stress on cytokine production. Adrenal demedullation of animals with a SNC demonstrated that the SNS, not the HPAA, was primarily responsible for the immunosuppressive effects of stress.

Cytotoxic T lymphocytes (CTL) induce apoptosis by engaging death receptors or by exocytosis of cytolytic granules containing granzyme (Gzm) proteases and perforin. The lamins, which maintain the structural integrity of the nuclear envelope, are cleaved by caspases during caspase-mediated apoptosis. Although death receptor engagement and GzmB activate caspases, CTL also induce apoptosis during caspase blockade. Both GzmA and GzmB directly and efficiently cleave laminB in vitro , in situ in isolated nuclei and in cells loaded with perforin and Gzms, even in the presence of caspase inhibitors. LaminB is cleaved by GzmA at concentrations of 3 nM, but GzmB is 50 times less active. GzmA cuts laminB at R392; GzmB cuts at the caspase VEVD231 site. Characteristic laminB fragments generated by Gzm proteolysis also are observed during CTL lysis, even in the presence of caspase inhibitors or in cells overexpressing bcl-2. Lamins A/C are direct substrates of GzmA, but not GzmB. GzmA and GzmB therefore directly target critical caspase substrates in caspase-resistant cells.

Many cell death pathways converge at the mitochondria to induce release of apoptogenic proteins and permeability transition, resulting in the activation of effector caspases responsible for the biochemical and morphological alterations of apoptosis. The death receptor pathway has been described as a triphasic process initiated by the activation of apical caspases, a mitochondrial phase, and then the final phase of effector caspase activation. Granzyme B (GrB) activates apical and effector caspases as well as promotes cytochrome c (cyt c) release and loss of mitochondrial membrane potential. We investigated how GrB affects mitochondria utilizing an in vitro cell-free system and determined that cyt c release and permeability transition are initiated by distinct mechanisms. The cleavage of cytosolic BID by GrB results in truncated BID, initiating mitochondrial cyt c release. BID is the sole cytosolic protein responsible for this phenomenon in vitro, yet caspases were found to participate in cyt c release in some cells. On the other hand, GrB acts directly on mitochondria in the absence of cytosolic S100 proteins to open the permeability transition pore and to disrupt the proton electrochemical gradient. We suggest that GrB acts by two distinct mechanisms on mitochondria that ultimately lead to mitochondrial dysfunction and cellular demise.

The cytotoxic T lymphocyte protease granzyme A induces caspase-independent cell death in which DNA single-strand nicking is observed instead of oligonucleosomal fragmentation. Granzyme A is a specific tryptase that concentrates in the nucleus of targeted cells and synergistically enhances DNA fragmentation induced by the caspase activator granzyme B. Here we show that granzyme A treatment of isolated nuclei enhances DNA accessibility to exogenous endonucleases. In vitro and after cell loading with perforin, GrnA completely degrades histone H1 and cleaves core histones into approximately 16-kDa fragments. Histone digestion provides a mechanism for unfolding compacted chromatin and facilitating endogenous DNase access to DNA during T cell and natural killer cell granule-mediated apoptosis.

BNIP3 (formerly NIP3) is a pro-apoptotic, mitochondrial protein classified in the Bcl-2 family based on limited sequence homology to the Bcl-2 homology 3 (BH3) domain and COOH-terminal transmembrane (TM) domain. BNIP3 expressed in yeast and mammalian cells interacts with survival promoting proteins Bcl-2, Bcl-X(L), and CED-9. Typically, the BH3 domain of pro-apoptotic Bcl-2 homologues mediates Bcl-2/Bcl-X(L) heterodimerization and confers pro-apoptotic activity. Deletion mapping of BNIP3 excluded its BH3-like domain and identified the NH(2) terminus (residues 1-49) and TM domain as critical for Bcl-2 heterodimerization, and either region was sufficient for Bcl-X(L) interaction. Additionally, the removal of the BH3-like domain in BNIP3 did not diminish its killing activity. The TM domain of BNIP3 is critical for homodimerization, pro-apoptotic function, and mitochondrial targeting. Several TM domain mutants were found to disrupt SDS-resistant BNIP3 homodimerization but did not interfere with its killing activity or mitochondrial localization. Substitution of the BNIP3 TM domain with that of cytochrome b(5) directed protein expression to nonmitochondrial sites and still promoted apoptosis and heterodimerization with Bcl-2 and Bcl-X(L). We propose that BNIP3 represents a subfamily of Bcl-2-related proteins that functions without a typical BH3 domain to regulate apoptosis from both mitochondrial and nonmitochondrial sites by selective Bcl-2/Bcl-X(L) interactions.

Granzyme B (GraB) is required for the efficient activation of apoptosis by cytotoxic T lymphocytes and natural killer cells. We find that GraB and perforin induce severe mitochondrial perturbation as evidenced by the release of cytochrome c into the cytosol and suppression of transmembrane potential (Δψ). The earliest mitochondrial event was the release of cytochrome c, which occurred at the same time as caspase 3 processing and consistently before the activation of apoptosis. Granzyme K/perforin or perforin treatment, both of which kill target cells efficiently but are poor activators of apoptosis in short-term assays, did not induce rapid cytochrome c release. However, they suppressed Δψ and increased reactive oxygen species generation, indicating that mitochondrial dysfunction is also associated with this nonapoptotic cell death.Pretreatment with peptide caspase inhibitors zVAD-FMK or YVAD-CHO prevented GraB apoptosis and cytochrome c release, whereas DEVD-CHO blocked apoptosis but did not prevent cytochrome c release, indicating that caspases act both up- and downstream of mitochondria. Of additional interest, Δψ suppression mediated by GraK or GraB and perforin was not affected by zVAD-FMK and thus was caspase independent. Overexpression of Bcl-2 and Bcl-XL suppressed caspase activation, mitochondrial cytochrome c release, Δψ suppression, and apoptosis and cell death induced by GraB, GraK, or perforin.In an in vitro cell free system, GraB activates nuclear apoptosis in S-100 cytosol at high doses, however the addition of mitochondria amplified GraB activity over 15-fold. GraB- induced caspase 3 processing to p17 in S-100 cytosol was increased only threefold in the presence of mitochondria, suggesting that another caspase(s) participates in the mitochondrial amplification of GraB apoptosis. We conclude that GraB-induced apoptosis is highly amplified by mitochondria in a caspase-dependent manner but that GraB can also initiate caspase 3 processing and apoptosis in the absence of mitochondria.

Interleukin (IL)-1, IL-2 and IL-6 influence central monoamine activity in a cytokine-specific manner. We demonstrated that whereas IL-2 increased hypothalamic and hippocampal norepinephrine (NE) utilization, and DA turnover in the prefrontal cortex, IL-6 induced profound elevations of serotonin (5-HT) and mesocortical dopamine (DA) activity in the hippocampus and prefrontal cortex [S. Zalcman, J.M. Green-Johnson, L. Murray, D.M. Nance, D.G. Dyck, H. Anisman, A. H. Greenberg, Cytokine-specific central monoamine alterations following IL-1, -2 and -6 administration, Brain Res. 643 (1994) 40-49]. IL-1, in contrast, induced a wide range of central monoamine alterations. We presently report that these cytokines also differentially influence behavior. Profound reductions in non-ambulatory and ambulatory exploration were induced in BALB/c mice following IL-1 administration. In contrast, IL-2-treated mice displayed significant increases in the time spent engaged in non-ambulatory exploration, digging, rearing (particularly the number of free rears), and in the investigation of a novel stimulus (i.e., increased number and duration of stimulus contacts). IL-6-treated mice, moreover, exhibited significant increases in the time spent engaged in ambulatory exploration, digging and rearing (particularly the number of free rears, which tended to be of short duration). Modest increases in locomotion and grooming were also observed in IL-6-treated animals. Plasma corticosterone levels did not vary significantly as a function of IL-6 treatment. Hence, cytokine-specific behavioral-activating effects were induced following administration of IL-2 and IL-6. We suggest that these effects have adaptive significance and relevance to sickness behavior; however, pathological outcomes (e.g., schizophrenia, anxious-like states, anxious depression, motor abnormalities) could develop should these cytokines be overproduced or dysregulated.

Nuclear factor κB (NFκB) is a ubiquitously expressed transcription factor that is regulated by the cytoplasmic inhibitor protein IκBα. Biological agents such as tumor necrosis factor α (TNFα), which activate NFκB, result in the rapid degradation of IκBα. Adenoviral-mediated gene transfer of Bcl-2 prevents apoptosis of neonatal ventricular myocytes induced by TNFα. In view of the growing evidence that NFκB may play an important role in regulating apoptosis, we determined whether TNFα and Bcl-2 could modulate the activity of NFκB in ventricular myocytes. Stimulation of myocytes with TNFα resulted in a 2.1-fold increase (p

We report that chlamydiae, which are obligate intracellular bacterial pathogens, possess a novel antiapoptotic mechanism. Chlamydia-infected host cells are profoundly resistant to apoptosis induced by a wide spectrum of proapoptotic stimuli including the kinase inhibitor staurosporine, the DNA-damaging agent etoposide, and several immunological apoptosis-inducing molecules such as tumor necrosis factor-α, Fas antibody, and granzyme B/perforin. The antiapoptotic activity was dependent on chlamydial but not host protein synthesis. These observations suggest that chlamydia may encode factors that interrupt many different host cell apoptotic pathways. We found that activation of the downstream caspase 3 and cleavage of poly (ADP-ribose) polymerase were inhibited in chlamydia-infected cells. Mitochondrial cytochrome c release into the cytosol induced by proapoptotic factors was also prevented by chlamydial infection. These observations suggest that chlamydial proteins may interrupt diverse apoptotic pathways by blocking mitochondrial cytochrome c release, a central step proposed to convert the upstream private pathways into an effector apoptotic pathway for amplification of downstream caspases. Thus, we have identified a chlamydial antiapoptosis mechanism(s) that will help define chlamydial pathogenesis and may also provide information about the central mechanisms regulating host cell apoptosis.

We tested whether prostaglandin synthesis mediates the lipopolysaccharide (LPS)-induced increase in splenic sympathetic nerve activity. Sprague-Dawley rats were pretreated with intravenous or intracerebroventricular injections of indomethacin, and splenic nerve activity was recorded after intravenous injections of LPS. In vehicle-pretreated rats, 100 micrograms LPS induced a 62.8 +/- 5.6% increase in splenic nerve activity beginning 22.7 +/- 2.7 min postinjection. All vehicle-pretreated animals responded to high (100 micrograms, 5 of 5 animals) and low (10 micrograms, 8 of 8 animals) doses of LPS. Both intravenous (15 mg/kg) and intracerebroventricular (50 micrograms) pretreatments with indomethacin delayed (F1.19 = 30.66, P < 0.001) the increase in nerve activity after 100 micrograms LPS. When given intravenously, 50 micrograms indomethacin (the intracerebroventricular dose) did not delay the response to intravenous LPS, indicating that the effects of intracerebroventricular indomethacin pretreatment were restricted to the central nervous system. Importantly, intracerebroventricular indomethacin reduced (2 of 7 animals) or completely blocked (5 of 7 animals) the splenic nerve response to the low dose of LPS (10 micrograms, iv). The indomethacin effects could not be accounted for by central release of vasopressin because intracerebroventricular injection of indomethacin did not alter baseline nerve activity or blood pressure, whereas intracerebroventricular injection of vasopressin rapidly increased both measures. Additionally, central injection of LPS did not elevate splenic nerve activity, whereas intracerebroventricular injection of prostaglandin E2 induced a rapid (2.2 +/- 2.7 min) increase in splenic nerve activity. These data indicate that central prostaglandin synthesis is an intermediate step whereby systemic LPS elicits an increase in sympathetic outflow to an immune organ.

Members of the CED-3/interleukin-1beta-converting enzyme (ICE) protease (caspase) family are synthesized as proforms, which are proteolytically cleaved and activated during apoptosis. We report here that caspase-2 (ICH-1/NEDD-2), a member of the ICE family, is activated during apoptosis by another ICE member, a caspase-3 (CPP32)-like protease(s). When cells are induced to undergo apoptosis, endogenous caspase-2 is first cleaved into three fragments of 32-33 kDa and 14 kDa, which are then further processed into 18- and 12-kDa active subunits. Up to 50 microM N-acetyl-Asp-Glu-Val-Asp-aldehyde (DEVD-CHO), a caspase-3-preferred peptide inhibitor, inhibits caspase-2 activation and DNA fragmentation in vivo, but does not prevent loss of mitochondrial function, while higher concentrations of DEVD-CHO (50 microM) inhibit both. In comparison, although the activity of caspase-3 is very sensitive to the inhibition of DEVD-CHO (50 nM), inhibition of caspase-3 activation as marked by processing of the proform requires more than 100 microM DEVD-CHO. Our results suggest that the first cleavage of caspase-2 is accomplished by a caspase-3-like activity, and other ICE-like proteases less sensitive to DEVD-CHO may be responsible for activation of caspase-3 and loss of mitochondrial function.

Granzyme B (GraB) induces apoptosis in the presence of perforin. Perforin polymerizes in the cell membrane to form a nonspecific ion pore, but it is not known where GraB acts to initiate the events that ultimately lead to apoptosis. It has been hypothesized that GraB enters the target cell through a perforin channel and then initiates apoptosis by cleaving and activating members of the ICE/Ced-3 family of cell death proteases. To determine if GraB can enter the cell, we treated YAC-1 or HeLa cells with FITC-labeled GraB and measured intracellular fluorescence with a high sensitivity CCD camera and image analyzer. GraB was internalized and found diffusely dispersed in the cell cytoplasm within 10 min. Uptake was inhibited at low temperature (4°C) and by pretreatment with metabolic inhibitors, NaF and DNP, or cytochalasin B, a drug that both blocks microfilament formation, and FITC-GraB remained on the cell membrane localized in patches. With the simultaneous addition of perforin and FITC-GraB, no significant increase in cytoplasmic fluorescence was observed over that found in cells treated only with FITC-GraB. However, FITC-GraB was now detected in the nucleus of apoptotic cells labeling apoptotic bodies and localized areas within and along the nuclear membrane. The ability of GraB to enter cells in the absence of perforin was reexamined using anti-GraB antibody immunogold staining of ultrathin cryosections of cells incubated with GraB. Within 15 min, gold particles were detected both on the plasma membrane and in the cytoplasm of cells with some gold staining adjacent to the nuclear envelope but not in the nucleus. Cells internalizing GraB in the absence of perforin appeared morphologically normal by Hoechst staining and electron microscopy. GraB directly microinjected into the cytoplasm of B16 melanoma cells induced transient plasma membrane blebbing and nuclear coarsening but the cells did not become frankly apoptotic unless perforin was added. We conclude that GraB can enter cells autonomously but that perforin initiates the apoptotic process and the entry of GraB into the nucleus.

To explore the role of the interleukin (IL)-1β converting enzyme (ICE) in neuronal apoptosis, we designed a mutant ICE gene (C285G) that acts as a dominant negative ICE inhibitor. Microinjection of the mutant ICE gene into embryonal chicken dorsal root ganglial neurons inhibits trophic factor withdrawal–induced apoptosis. Transgenic mice expressing the fused mutant ICE-lacZ gene under the control of the neuron specific enolase promoter appeared neurologically normal. These mice are deficient in processing pro–IL-1β, indicating that mutant ICEC285G blocks ICE function. Dorsal root ganglial neurons isolated from transgenic mice were resistant to trophic factor withdrawal–induced apoptosis. In addition, the neurons isolated from newborn ICE knockout mice are similarly resistant to trophic factor withdrawal–induced apoptosis. After permanent focal ischemia by middle cerebral artery occlusion, the mutant ICEC285G transgenic mice show significantly reduced brain injury as well as less behavioral deficits when compared to the wild-type controls. Since ICE is the only enzyme with IL-1β convertase activity in mice, our data indicates that the mutant ICEC285G inhibits ICE, and hence mature IL-1β production, and through this mechanism, at least in part, inhibits apoptosis. Our data suggest that genetic manipulation using ICE family dominant negative inhibitors can ameliorate the extent of ischemia-induced brain injury and preserve neurological function.

The responses of two substrains of Balb/c mice (Epilepsy Prone and Epilepsy Resistant) to immunization with sheep red blood cells (SRBC) were examined to determine whether chronic neurochemical differences between the two strains could influence B cell function. Anti-SRBC IgG production in the Epilepsy Prone (EP) strain was reduced relative to the Epilepsy Resistant (ER) strain, while anti-SRBC IgM production was unaffected. No differences were found in in vitro antibody (Ab) production or T lymphocyte function between the EP and ER strains, suggesting that in vivo conditions rather than an intrinsic cellular defect are responsible for reduced IgG production by EP mice. Basal splenic norepinephrine (NE) levels were significantly higher in EP mice than those in ER mice, and remained significantly higher following immunization. ER mice treated with the β2 adrenergic agonist terbutaline on days 4, 5 and 6 after immunization produced significantly lower numbers of IgG PFC than did saline treated controls. Addition of NE during later stages of in vitro immunization suppressed both anti-SRBC IgM and IgG production by splenic lymphocytes from Balb/c mice, and NE was found to decrease IFNγ production. These observations suggest that dysregulation of splenic NE can have an impact on the immune response.

We report here the isolation and characterization of a new member of the ice/ced-3 family of cell death genes, named ich-3. The predicted amino acid sequence of Ich-3 protein shares 54% identity with murine interleukin-1beta converting enzyme (ICE). Overexpression of ich-3 in Rat-1 and HeLa cells induces apoptosis, which can be inhibited by CrmA and Bcl-2. The mRNA and proteins of ich-3 are dramatically induced in vivo upon stimulation with lipopolysaccharide, an inducer of septic shock. The ich-3 gene product can be cleaved by cytotoxic T cells granule serine protease granzyme B, suggesting that Ich-3 may mediate apoptosis induced by granzyme B. Ich-3 does not process proIL-1beta directly but does promote proIL-1beta processing by ICE. These results suggest that Ich-3 may play a very important role in apoptosis and inflammatory responses and may be an upstream regulator of ICE.

The hyaluronan (HA) receptor RHAMM is an important regulator of cell growth. Overexpression of RHAMM is transforming and is required for H-ras transformation. The molecular mechanism underlying growth control by RHAMM and other extracellular matrix receptors remains largely unknown. We report that soluble RHAMM induces G2/M arrest by suppressing the expression of Cdc2/Cyclin B1, a protein kinase complex essential for mitosis. Down-regulation of RHAMM by use of dominant negative mutants or antisense of mRNA also decreases Cdc2 protein levels. Suppression of Cdc2 occurs as a result of an increased rate of cdc2 mRNA degradation. Moreover, tumor cells treated with soluble RHAMM are unable to form lung metastases. Thus, we show that mitosis is directly linked to RHAMM through control of Cdc2 and Cyclin B1 expression. Failure to sustain levels of Cdc2 and Cyclin B1 proteins leads to cell cycle arrest.

We describe the isolation and characterization of the murine gene encoding RHAMM, a hyaluronan receptor which regulates focal adhesion turnover, is required for cell locomotion and is a critical downstream regulator of ras transformation. The RHAMM gene spans at least 20 kb and comprises 14 exons ranging in size from 75 to 1099 bp. Primer extension studies indicate that the major transcription start point is in position -31, relative to the start Met. Northern blot analysis of mouse fibroblast RNA identified two hybridizing species of 4.2 and 1.7 kb. Comparison of cDNA clones and RT-PCR products with the genomic clones identified alternately spliced exons in both the coding and 5′ noncoding regions of RHAMM . In the coding region exon 4 is alternately spliced. The major RHAMM transcript ( RHAMM1 ) in 3T3 fibroblasts does not contain exon 4 and encodes a protein of 70 kDa. A minor transcript containing exon 4, namely RHAMM v4, encodes a 73-kDa protein, as demonstrated by isoform-specific antibodies. Western analysis demonstrated both a major 70-kDa (RHAMM 1) and minor 73-kDa RHAMM protein (v4) in 3T3 murine fibroblast cell lysates. The functional significance of these two isoforms is currently being investigated.

The baculovirus antiapoptotic protein p35 inhibited the proteolytic activity of human interleukin-1 beta converting enzyme (ICE) and three of its homologs in enzymatic assays. Coexpression of p35 prevented the autoproteolytic activation of ICE from its precursor form and blocked ICE-induced apoptosis. Inhibition of enzymatic activity correlated with the cleavage of p35 and the formation of a stable ICE-p35 complex. The ability of p35 to block apoptosis in different pathways and in distantly related organisms suggests a central and conserved role for ICE-like proteases in the induction of apoptosis.

Granzymes are a family of granule-associated serine esterases that mediate apoptosis by cytotoxic T lymphocytes and natural killer cells. We have previously shown that cdc2, the mitosis-regulating cyclin-dependent kinase, is required for granzyme B-induced apoptosis in target cells. In addition, granzyme B induces premature activation and tyrosine dephosphorylation of cdc2 during apoptosis. Throughout most of the cell cycle and until the cell is prepared to enter mitosis, cdc2 kinase activity is negatively regulated by phosphorylation of a residue within its adenosine triphosphate-binding domain by Wee1, a nuclear kinase that maintains mitotic timing in eukaryotic cells. We have transiently expressed c-myc epitope-tagged Wee1 cDNA in BHK cells. Cells that expressed Wee1 in the nucleus became resistant to apoptosis induced by granzyme B and perforin. Wee1-transfected cells also exhibited markedly increased cdc2 tyrosine phosphorylation. Thus, Wee1 can rescue cells from granzyme-induced apoptosis by preventing cdc2 dephosphorylation.

Transforming growth factor (TGF-beta) is a family of multifunctional signalling molecules that play a fundamental role in both normal and malignant cell behavior. Procedures that alter mouse TGF-beta 1 gene expression provide an important approach for analyzing the complex regulatory processes associated with this member of the growth factor family. Therefore, we have designed oligodeoxyribonucleotides (oligos) in an antisense orientation, which are complementary to regions of the TGF-beta 1 message, in an attempt to obtain an oligo sequence that specifically reduces TGF-beta 1 synthesis. We observed that oligos containing a mixture of phosphorothioate and phosphodiester linkages were less toxic and more specific when compared to those only containing phosphorothioate. A non-toxic sequence was identified that markedly reduced the levels of TGF-beta 1 in oligo-treated malignant mouse fibrosarcoma cells. The invasive and metastatic properties of these fibrosarcoma cells were also significantly decreased following treatment with the antisense oligo. The results indicate an important role for altered TGF-beta 1 expression in the regulation of malignant cell proliferation, invasion and metastasis. These results also indicate that this oligo sequence is a useful tool for studies directed towards understanding the complex relationships between TGF-beta 1 and cellular regulation.

Cytokine-specific alterations of monoamine activity were evident in the hypothalamus, hippocampus and prefrontal cortex 2 h following peripheral administration of recombinant interleukin (IL)-1β, IL-2 and IL-6 (200 ng, i.p.) in male, BALB/c mice. IL-1 induced the broadest range of neurochemical changes, affecting central norepinephrine (NE), serotonin (5-HT) and dopamine (DA) activity. In particular, IL-1 enhanced NE turnover in the hypothalamus and hippocampus, 5-HT turnover in the hippocampus and prefrontal cortex (owing to increased utilization and reduced content of the transmitters in these brain regions), and enhanced DA utilization in the prefrontal cortex. IL-6 increased 5-HT and DA activity in the hippocampus and prefrontal cortex in a manner similar to IL-1, but failed to affect central NE activity. Moreover, IL-2 increased hypothalamic NE turnover (reflecting a profound increase in NE utilization) and enhanced DA turnover in the prefrontal cortex, but did not influence central 5-HT activity. Hence, these cytokines differentially altered neurochemical activity in brain regions that mediate neuroimmune interactions and that are influenced by physical and psychological stressors. In addition to the neurochemical changes, plasma corticosterone concentrations were profoundly enhanced in IL-1-treated animals, but not significantly altered by IL-2 or IL-6 treatment. The IL-1-induced corticosterone elevations did not significantly correlate with alterations of hypothalamic NE activity.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been a gene of choice in Northern blot analyses as an internal RNA loading control. We have investigated the expression of GAPDH and 28S-ribosomal RNA (28S rRNA) genes in mouse 10T 1 2 cells and in a variety of tumorigenic and highly malignant metastatic cell lines derived from the 10T 1 2 cell line. We observed that GAPDH mRNA levels varied markedly among the tumorigenic and highly malignant cell lines and were elevated in these cell lines when compared to the normal mouse 10T 1 2 cells. In contrast, the levels of 28S rRNA did not significantly vary among the tumorigenic and highly malignant cell lines and were approximately at the same level as that found in the normal parental mouse 10T 1 2 cell line. These observations indicate that much caution should be taken when using GAPDH gene expression as an RNA loading control for Northern blots. Based upon these observations, we recommend the use of 28S rRNA gene expression as a preferred RNA loading control for Northern blot analysis in which total RNA is used.

An antigen-capture sandwich enzyme-linked immunosorbent assay (ELISA) was developed for a novel protein granulophysin, a constituent of the platelet dense granule (DG) membrane and used to characterize patients with dense granule storage pool deficiency (delta-SPD). The assay uses two monoclonal antibodies against the protein, one of which is conjugated to peroxidase. Purified DGs, an enriched source of the protein, were used for the standard curve. Granulophysin levels were only low in forms of delta-SPD associated with albinism. Granulophysin levels in platelet homogenates of 30 patients with the Hermansky-Pudlak syndrome form of delta-SPD were 1/4 to 1/5 of levels in controls or obligate heterozygotes. Two patients with the Chediak-Higashi form of delta-SPD syndrome also had markedly reduced levels of granulophysin. Patients with other forms of delta-SPD had normal levels of granulophysin. Two sisters with delta-SPD in one family had normal granulophysin present in empty dense granule membrane vesicles. Three members of another family with delta-SPD had low DG counts but normal granulophysin levels, indicating that in this group the level of granulophysin was maintained despite the reduction in granule formation. Thus, granulophysin quantitation facilitates characterization of delta-SPD patients and may provide clues to the nature of defective granules in delta-SPD subtypes.

Transforming growth factor-beta 1 (TGF-beta 1) stimulated DNA synthesis (3-fold) in BALBc/3T3 fibroblasts following 24 hours of growth factor exposure. Since ribonucleotide reductase is important for the coordination of DNA synthesis and cell proliferation, we investigated the hypothesis that cells like BALB/c 3T3, which are TGF-beta 1 responsive, would exhibit modifications in expression of the gene for ribonucleotide reductase following growth factor treatment. We observed 2.6, 4.1, and 4.8-fold increases in ribonucleotide reductase activity following TGF-beta 1 exposure for 6, 12, and 24 hours, respectively. Increased ribonucleotide reductase R2 gene expression (3, 3.7, and 4.5-fold) and R1 gene expression (2,2.5, and 2.6-fold) were observed following 6, 12, and 24 hours of TGF-beta 1 treatment, respectively. Western blots indicated 2.2, 3.1, and 4.1-fold increases in protein R2 levels at 6, 12, and 24 hours exposure to TGF-beta 1, whereas 2.6 and 3.3-fold elevations in R1 protein levels were observed at 12 and 24 hours post-TGF-beta 1 exposure. These TGF-beta 1 mediated modifications in ribonucleotide reductase gene expression occurred, in part, prior to any detectable changes in the rate of DNA synthesis, demonstrating alterations in the normal regulation of ribonucleotide reductase. Furthermore, these alterations could be markedly reduced by prolonged pretreatment with 12-O-tetradecanoylphorbol-13-acetate (R2 gene expression increased by only 1.3, 1.5 and 2.3-fold after 6, 12, and 24 hours of TGF-beta 1 treatment, respectively), suggesting a role for a protein kinase C pathway in the TGF-beta 1 regulated changes in ribonucleotide reductase gene expression. These results indicate for the first time that TGF-beta 1 can regulate the expression of the two genes for ribonucleotide reductase in BALB/c 3T3 fibroblasts, and suggest that regulation of these genes plays an important role in critical events involved in growth factor modulation of normal and transformed cell proliferation.

We recently reported the purification of a lymphocyte granule protein called "fragmentin," which was identified as a serine protease with the ability to induce oligonucleosomal DNA fragmentation and apoptosis (Shi, L., R. P. Kraut, R. Aebersold, and A. H. Greenberg. 1992. J. Exp. Med. 175:553). We have now purified two additional proteases with fragmentin activity from lymphocyte granules. The three proteases are of two types; one has the unusual ability to cleave a tripeptide thiobenzyl ester substrate after aspartic acid, similar to murine cytotoxic cell protease I/granzyme B, while two are tryptase-like, preferentially hydrolyzing after arginine, and bear some homology to human T cell granule tryptases, granzyme 3, and Hanukah factor/granzyme A. Using tripeptide chloromethyl ketones, the pattern of inhibition of DNA fragmentation corresponded to the inhibition of peptide hydrolysis. The Asp-ase fragmentin was blocked by aspartic acid-containing tripeptide chloromethyl ketones, while the tryptase fragmentins were inhibited by arginine-containing chloromethyl ketones. The two tryptase fragmentins were slow acting and were partly suppressed by blocking proteins synthesis with cycloheximide in the YAC-1 target cell. In contrast, the Asp-ase fragmentin was fast acting and produced DNA damage in the absence of protein synthesis. Using a panel of unrelated target cells of lymphoma, thymoma, and melanoma origin, distinct patterns of sensitivity to the three fragmentins were observed. Thus, these three granule proteases make up a family of fragmentins that activate DNA fragmentation and apoptosis by acting on unique substrates in different target cells.

We report the purification from a rat natural killer (RNK) large granular lymphocyte leukemia of a 32-kD granule protein that induces rapid DNA fragmentation and apoptosis. The protein, which we have called "fragmentin," was capable of causing DNA from intact YAC-1 cells to be cleaved into oligonucleosomal-sized fragments and producing severe chromatin condensation within 1 h. Amino acid sequence of tryptic peptides indicated that fragmentin was highly homologous to the NK and T cell granule serine proteases RNK protease 1 and mouse cytotoxic T cell protease I (CCPI)/granzyme B. Preincubation with the serine esterase inhibitor 3,4-dichloroisocoumarin blocked fragmentin-induced DNA damage, but had no effect on cytolysin. Fragmentin activity against four lymphoma target cells was completely dependent on the presence of cytolysin. Fragmentin produced rapid membrane damage as well as DNA fragmentation at nonlytic cytolysin doses, suggesting that fragmentin activity was not limited to its effects on the nucleus. Fragmentin and cytolysin activity were completely inhibited by EGTA, indicating the process was Ca2+ dependent. A role for cytolysin in endocytosis of fragmentin was suggested by the observation that treatment of YAC-1 with cytochalasin B or sodium azide and 2-deoxyglucose blocked DNA fragmentation but not cytolysin activity. A 30-kD N alpha-CBZ-L-lysine thiobenzyl esterase, which copurified with fragmentin, was inactive on its own but was able to synergistically amplify the DNA damage induced by fragmentin in the presence of cytolysin. Fragmentin activity was not dependent on protein synthesis, as cycloheximide treatment of YAC-1 cells did not prevent DNA damage. We postulate that fragmentin is the molecular mediator of NK cell-mediated DNA fragmentation and apoptosis.

Previous investigations have indicated that the suppression of proliferation by transforming growth factor (TGF) beta 1 is often lost upon cellular transformation, and that proliferation of some tumors is stimulated by TGF-beta. The present study provides the first observation of a link between TGF-beta 1 regulation of this process and alterations in the expression of ribonucleotide reductase, a highly controlled rate-limiting step in DNA synthesis. A series of radiation and T24-H-ras-transformed mouse 10T1/2 cell lines exhibiting increasing malignant potential was evaluated for TGF-beta 1 induced alterations in ribonucleotide reductase M1 and M2 gene expression. Early increases in M1 and/or M2 message and protein levels were observed only in malignant cell lines. The TGF-beta 1 induced changes in M1 and/or M2 gene expression occurred prior to any detectable changes in the rates of DNA synthesis, supporting the novel concept that ribonucleotide reductase gene expression can be elevated by TGF-beta 1 without altering the proportion of cells in S phase. T24-H-ras-transformed 10T1/2 cells were transfected with a plasmid containing the coding region of TGF-beta 1 under the control of a zinc-sensitive metallothionein promoter. When these cells were cultured in the presence of zinc, a large induction of TGF-beta 1 message was observed within 1 h. Both M1 and M2 genes were also induced, with increased mRNA levels appearing 2 h after zinc treatment, or 1 h after TGF-beta 1 message levels were clearly elevated. In total, the data suggests a mechanism of autocrine stimulation of malignant cells by TGF-beta 1, in which early alterations in the regulation of ribonucleotide reductase may play an important role.

Transforming growth factor-beta (TGF-beta) can regulate cell growth and differentiation as well as production of extracellular matrix proteins. Elevated production of TGF-beta has been associated with human and rodent chronic inflammatory and fibrotic diseases. Using immunohistochemical staining, we have examined lung sections of patients with advanced idiopathic pulmonary fibrosis (IPF), a disease characterized by chronic inflammation and fibrosis and demonstrated a marked and consistent increase in TGF-beta production in epithelial cells and macrophages when compared to patients with nonspecific inflammation and those with no inflammation or fibrosis. In patients with advanced IPF, intracellular staining with anti-LC (1-30) TGF-beta antibody was seen prominently in bronchiolar epithelial cells. In addition, epithelial cells of honeycomb cysts and hyperplastic type II pneumocytes stained intensely. Anti-CC (1-30) TGF-beta antibody, which reacts with extracellular TGF-beta, was localized in the lamina propria of bronchioles and in subepithelial regions of honeycomb cysts in areas of dense fibroconnective tissue deposition. The close association of subepithelial TGF-beta to the intracellular form in advanced IPF suggests that TGF-beta was produced and secreted primarily by epithelial cells. Because of the well-known effects of TGF-beta on extracellular matrix formation and on epithelial cell differentiation, the increased production of TGF-beta in advanced IPF may be pathogenic to the pulmonary fibrotic and regenerative responses seen in this disease.

In recent years, experimental systems have developed to analyze genetic and epigenetic regulation of the metastatic phenotype. Numerous studies have uncovered a potent role for transforming oncogenes in metastatic conversion. In addition, it has been shown that oncoprotein products operate in a dose-dependent fashion. The continued expression of oncoproteins is required to induce and regulate metastatic dissemination of tumor cells and, consequently, many of the signal transduction pathways that are controlled by the oncogene products can regulate metastasis. Exogenous growth factors that act through these same pathways also alter metastatic potential. Some primary and immortalized cells can be transformed by oncogenes but remain completely benign and nonmetastatic. Malignant transformation can be achieved in these cells through the cooperative interaction of specific oncogenes or loss of active suppression regulated by recessive genetic determinants. Therefore, it is likely that tumor cells acquire the metastatic phenotype through the cooperative interaction of dominant and recessive genetic alterations. This model is consistent with the correlative data accumulating in studies of human tumor specimens where more malignant carcinomas often contain both activating mutations in oncogenes and either inactivating mutations or loss of tumor-suppressor genes.

Highly metastatic mouse 10T1/2 cell lines (Ciras 2, Ciras 3 and dGC2M5) which have been T24-H-ras transfected, are shown to have differential responses in metastatic properties when grown in the presence of the processing inhibitors, swainsonine, castanospermine and deoxymannojirimycin. Concanavalin A binding data indicated the inhibitors caused similar shifts in oligo-saccharide structures, resulting in more high mannose character for all cell lines. However, swainsonine inhibited the experimental metastasis of dGC2M5, but did not affect the metastatic properties of Ciras 2 and Ciras 3. Inversely, castanospermine reduced experimental metastasis of Ciras 2 and 3 and did not inhibit dGC2M5. These results show that closely related metastatic cell lines respond differently in their metastatic ability when changes occur in N-linked oligosaccharide content. This observation emphasizes the importance of oligosaccharide structure in the malignant phenotype and indicates that some caution should be used when generalizing about the effects of processing inhibitors on a complex process like metastasis.

Overexpression of an activated ras gene in the rat embryo fibroblast line REF52 results in growth arrest at either the G1/S or G2/M boundary of the cell cycle. Both the DNA tumor virus proteins simian virus 40 large T antigen and adenovirus 5 E1a are able to rescue ras induced lethality and cooperate with ras to fully transform REF52 cells. In this report, we present evidence that the wild-type activity of the tumor suppressor gene p53 is involved in the negative growth regulation of this model system. p53 genes encoding either a p53Val-135 or p53Pro-193 mutation express a highly stable p53 protein with a conformation-dependent loss of wild-type activity and the ability to eliminate any endogenous wild-type p53 activity in a dominant negative manner. In cotransfection assays, these mutant p53 genes are able to rescue REF52 cells from ras-induced growth arrest, resulting in established cell lines which express elevated levels of the ras oncoprotein and show morphological transformation. Full transformation, as assayed by tumor formation in nude mice, is found only in the p53Pro-193-plus-ras transfectants. These cells express higher levels of the ras protein than do the p53Val-135-plus-ras-transfected cells. Transfection of REF52 cells with ras alone or a full-length genomic wild-type p53 plus ras results in growth arrest and lethality. Therefore, the selective event for p53 inactivation or loss during tumor progression may be to overcome a cell cycle restriction induced by oncogene overexpression (ras). These results suggest that a normal function of p53 may be to mediate negative growth regulation in response to ras or other proliferative inducing signals.

SUMMARY It has been reported that lymphocytes from peripheral blood (PBL) cultured with interleukin-2 (IL-2) produce predominantly CD16+ lymphokine-activated killer (LAK) cells. We developed a two-step method to generate LAK cells from human PBL in long-term cultures (10–12 days) with recombinant human IL-2 (rhIL-2) and characterized the evolving LAK cell population by testing its phenotype and cytotoxic activity as a function of time. The starting PBL displayed some natural killer (NK) cytotoxicity but no LAK activity. At day 6, the cells were a mixed population of about 80% CD3+ and 6% CD16+ cells. Little proliferation was evident but strong LAK activity was detected. After 10–12 days, major cell expansion had occurred and they were essentially a pure (>90%) CD3+CD16-CD56- cell population large granular lymphocyte (LGL) by morphology that displayed strong non-MHC-restricted killing activity (> 200 lytic units). Over the same period of time, the CD16+ cells had almost completely regressed in these cultures. This preferential induction of CD+ LAK cells was not an effect of IL-2 concentration as 10 U/ml was as effective as 500 U/ml. Further characterization revealed a major population of CD4+ (60%) and CD8+ (30%) with a smaller fraction (

Secreted phosphoprotein I (SPP), also known as 2ar, osteopontin, 44-kDa bone phosphoprotein, bone sialoprotein I, and transformation-related phosphoprotein, is a 41.5-kDa glycosylated phosphoprotein secreted by many mammalian cell lines and expressed in a limited set of tissues. Using a cDNA probe, we found that SPP mRNA, which is barely detectable in normal mouse epidermis, was expressed at moderate-to-high levels in 2 of 3 epidermal papillomas and at consistently high levels in 7 of 7 squamous-cell carcinomas induced by an initiation-promotion regimen. This contrasts with the transient induction we had previously observed after a single application of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). In a set of 5 independently isolated T24-H-ras-transfected mouse C3H 10T1/2 cell lines, the levels of SPP mRNA correlated well with ras mRNA levels and with both experimental and spontaneous metastatic ability. SPP mRNA expression was also elevated in a derivative of mouse LTA cells transfected with genomic DNA from B16F1 melanoma cells and selected for increased experimental metastatic ability in the chick embryo. This apparent association of SPP expression with invasion, progression and metastasis, along with the presence of a functional ArgGlyAsp (RGD) cell adhesion site in SPP (osteopontin), leads us to propose that SPP may act as an autocrine adhesion factor for tumor cells.

We have examined the effects of transformation by activated H-ras and other transforming oncogenes on the activity of the enzyme, heparanase. Degradation of 3H-N-acetylated-partially N-desulfated heparan sulfate by cellular extracts of the transformants was assessed by gel permation chromatography. More extensive degradation was observed with 10T1/2 mouse embryo fibroblasts transfected with an activated H-ras oncogene. The cells having the highest metastatic potential (CIRAS-3) were shown to contain the greatest heparanase activity, giving 49% higher levels of activity than parental cells (P less than 0.0002). Furthermore, the enzyme activity produced by a series of H-ras transformed cell lines increased progressively with metastatic potential (non-parametric rank correlation coefficient r = 0.96). Transfection of NIH 3T3 fibroblasts with activated H-ras, v-src or v-fes oncogenes, which induced the metastatic phenotype, did not lead to large increases in heparanase activities. Also, inhibition of ras-induced malignancy by cotransfection of rat REF cells with the Ad2 E1a oncogene did not produce significant declines in heparanase activities. These results are consistent with the view that modifications in heparanase activity can play a role in the complex process of metastasis in some, but not all situations.

Recombinant IL-1-β, which is capable of stimulating the pituitary-adrenal axis to secrete corticosterone, was paired with environmental cues in either a taste aversion or odor conditioning procedure. Among mice receiving paired delivery of cues and IL-1, subsequent re-exposure to cues elicited corticosterone production. This response was significantly greater than in animals that were conditioned but not re-exposed to the cues or were exposed to the cues alone. These results indicate that the IL-1 activation of adrenal cortical secretion can be conditioned to environmental stimuli.

Driven in part by the development of genomics, proteomics, and bioinformatics as new disciplines, there has been a tremendous resurgence of interest in physical methods to investigate macromolecular structure and function in the context of living cells. This volume in Methods in Cell Biology is devoted to biophysical techniques in vitro and their applications to cellular biology. The volume covers methods-oriented chapters on fundamental as well as cutting-edge techniques in molecular and cellular biophysics.This book is directed toward the broad audience of cell biologists, biophysicists, pharmacologists, and molecular biologists who employ classical and modern biophysical technologies or wish to expand their expertise to include such approaches. It will also interest the biomedical and biotechnology communities for biophysical characterization of drug formulations prior to FDA approval. It describes techniques in the context of important biological problems. It delineates critical steps and potential pitfalls for each method. It includes full color plates to illustrate techniques.

Sympathetic activation occurs rapidly following intracerebroventricular (icv) injection of prostaglandin E2(PGE2). This study examined whether neuropeptides mediate PGE2-induced sympathetic nerve activation in urethane/chloralose-anesthetized Sprague-Dawley rats. Animals were pretreated (20.0 microg, icv) with the following receptor antagonists; CRF ([D-Phe12,Nle21,38,Calpha-MeLeu37]CRF12-41), AVP-V1 (Des-Gly-[Phaa1, D-Tyr(Et)2,Lys6,Arg8]-vasopressin), or OT (OT+V1, [d(CH2)5,Tyr(Me)2,Orn8]-vasotocin) followed 20 min later by PGE2 (2.0 microg, icv). Pretreatment with the CRF antagonist attenuated the increase in renal nerve activity induced by PGE2 when measured 10 and 30 min post-injection. PGE2-induced renal nerve activity was also inhibited at both time points by the AVP antagonist and, to a similar extent, the OT antagonist. The AVP antagonist did not effect splenic nerve responses to PGE2 whereas the CRF antagonist produced an incomplete and transient reduction in PGE2-induced activation of the splenic nerve. However, the OT antagonist completely blocked the activation of the splenic nerve after central injection of PGE2. ICV injections of AVP and OT produced immediate changes in splenic and renal nerve activity whereas CRF failed to alter the activity of either nerve in anesthetized or conscious animals. Thus, PGE2 acts through neuropeptide-specific pathways to initiate sympathetic outflow and OT is a specific component of the sympathetic pathway innervating the spleen.

CD47 is a surface receptor that induces either coactivation or apoptosis in lymphocytes, depending on the ligand(s) bound. Interestingly, the apoptotic pathway is independent of caspase activation and cytochrome c release and is accompanied by early mitochondrial dysfunction with suppression of mitochondrial membrane potential (Deltapsim). Using CD47 as bait in a yeast two-hybrid system, we identified the Bcl-2 homology 3 (BH3)-only protein 19 kDa interacting protein-3 (BNIP3), a pro-apoptotic member of the Bcl-2 family, as a novel partner. Interaction between CD47 and the BH3-only protein was confirmed by immunoprecipitation analysis, and CD47-induced apoptosis was inhibited by attenuating BNIP3 expression with antisense oligonucleotides. Finally, we showed that the C-terminal domain of thrombospondin-1 (TSP-1), but not signal-regulatory protein (SIRPalpha1), is the ligand for CD47 involved in inducing cell death. Immunofluorescence analysis of CD47 and BNIP3 revealed a partial colocalization of both molecules under basal conditions. After T cell stimulation via CD47, BNIP3 translocates to the mitochondria to induce apoptosis. These results show that the BH3-dependent apoptotic pathways, previously shown to be activated by intracellular pro-apoptotic events, can also be turned on by surface receptors. This new pathway results in a fast induction of cell death resembling necrosis, which is likely to play an important role in lymphocyte regulation at inflammatory sites and/or in the vicinity of thrombosis.

Both the hypothalamic pituitary adrenal axis (HPAA) and the sympathetic nervous system (SNS) can inhibit immune function and are regarded as the primary efferent pathways for neural-immune interactions. To determine if this relationship is maintained in vivo in response to an inflammatory stimulus, rats were injected intravenously (iv) with various doses of lipopolysaccharide (LPS) and splenic cytokine mRNA and protein levels were measured at several dose and time intervals post-injection. The spleen was chosen as the target organ because both the neural and hormonal inputs to the spleen can be selectively removed by splenic nerve cut (SNC) and adrenalectomy (ADX), respectively. Data from our dose response studies established that maximum levels of splenic cytokines were induced in response to relatively low doses of LPS. Minimal changes in LPS-induced splenic cytokine levels were observed in response to ADX, SNC, or a combination of the two procedures across several doses of LPS. These results suggest that there are aspects of immune regulation that are functionally removed from these central modulatory systems and that the counter-regulatory responses induced by LPS have minimal impact on the concurrent induction of cytokines by this inflammatory stimulus. The conceptual model of neural-immune regulation as an inhibitory feedback system, at least with regards to the early activational effects induced by an inflammatory stimulus, was not supported by these studies.

Apoptosis and necrosis need to be differentiated in order to distinguish drug-induced cell death from spontaneous cell death due to hypoxia. The ability to differentiate between these two modes of cell death, especially at an early stage in the process, could have a significant impact on accessing the outcome of anticancer drug therapy in the clinic. Nuclear magnetic resonance spectroscopy was used to distinguish apoptosis from necrosis in human cervical carcinoma (HeLa) cells. Apoptosis was induced by treatment with the topoisomerase II inhibitor etoposide, whereas necrosis was induced by the use of ethacrynic acid or cytochalasin B. We found that the intensity of the methylene resonance increases significantly as early as 6 h after the onset of apoptosis, but that no such changes occur during necrosis. The spectral intensity ratio of the methylene to methyl resonances also shows a high correlation with the percentage of apoptotic cells in the sample (r2=0.965, P

We have studied ceBNIP3, the orthologue of BNIP3 in C. elegans. Sequence analysis reveals that the different domains of BNIP3 have been conserved throughout evolution. ceBNIP3 contains a C-terminal transmembrane (TM) domain, a conserved domain (CD) of 19 amino acids, a BCL-2 homology-3 (BH3)-like domain and a PEST sequence. ceBNIP3 is expressed primarily as a 25 kDa monomer and a 50 kDa homodimer. After transfection, ceBNIP3 protein is rapidly degraded through a ubiquitin-dependent pathway by the proteasome. Like BNIP3, the TM domain of ceBNIP3 mediates the localization of the protein to mitochondria and is also necessary for homodimerization and cell death in mammalian cells. Neither the putative BH3 domain nor conserved domain is necessary for killing. ceBNIP3 protein interacts with CED-9 and BCL-XL, but unlike other pro-apoptotic BCL-2 family members, the BH3-like domain does not participate in dimerization. The ceBNIP3 TM domain mediates interaction with both CED-9 and BCL-XL. ceBNIP3 interacts with CED-3 but co-expression of CED-3 and ceBNIP3 does not significantly enhance induction of cell death in the presence or absence of CED-4. ceBNIP3 kills mammalian cells by a caspase-independent mechanism. In conclusion, we find that although ceBNIP3 interacts with CED-9 and CED-3 it kills by a BH3- and caspase-independent mechanism.

Elevated concentrations of hyaluronan (HA) are associated with the accumulation of macrophages in the lung after injury. We have investigated the role of HA in the inflammatory and fibrotic responses to lung injury using the intratracheal instillation of bleomycin in rats as a model. After bleomycin-induced lung injury, both HA content in bronchoalveolar lavage (BAL) and staining for HA in macrophages accumulating in injured areas of the lung were maximal at 4 d. Increased HA in BAL correlated with increased locomotion of isolated alveolar macrophages. HA-binding peptide was able to specifically block macrophage motility in vitro. Importantly, systemic administration of HA-binding peptide to rats before injury not only decreased alveolar macrophage motility and accumulation in the lung, but also reduced lung collagen alpha (I) messenger RNA and hydroxyproline contents. We propose a model in which HA plays a critical role in the inflammatory response and fibrotic consequences of acute lung injury.

Many apoptotic signaling pathways are directed to mitochondria, where they initiate the release of apoptogenic proteins and open the proposed mitochondrial permeability transition (PT) pore that ultimately results in the activation of the caspase proteases responsible for cell disassembly. BNIP3 (formerly NIP3) is a member of the Bcl-2 family that is expressed in mitochondria and induces apoptosis without a functional BH3 domain. We report that endogenous BNIP3 is loosely associated with mitochondrial membrane in normal tissue but fully integrates into the mitochondrial outer membrane with the N terminus in the cytoplasm and the C terminus in the membrane during induction of cell death. Surprisingly, BNIP3-mediated cell death is independent of Apaf-1, caspase activation, cytochrome c release, and nuclear translocation of apoptosis-inducing factor. However, cells transfected with BNIP3 exhibit early plasma membrane permeability, mitochondrial damage, extensive cytoplasmic vacuolation, and mitochondrial autophagy, yielding a morphotype that is typical of necrosis. These changes were accompanied by rapid and profound mitochondrial dysfunction characterized by opening of the mitochondrial PT pore, proton electrochemical gradient (Deltapsim) suppression, and increased reactive oxygen species production. The PT pore inhibitors cyclosporin A and bongkrekic acid blocked mitochondrial dysregulation and cell death. We propose that BNIP3 is a gene that mediates a necrosis-like cell death through PT pore opening and mitochondrial dysfunction.

The impact of plasma corticosterone levels on the sympathetic nervous system (SNS) response to intravenous lipopolysaccharide (LPS) or intracerebroventricular injections of PG was studied in anesthetized (urethan-chloralose) male Sprague-Dawley rats. For this, electrophysiological recordings of splenic and renal nerves were completed in control or adrenalectomized (ADX) rats. LPS (10 μg iv) similarly increased splenic and renal nerve activity in control rats with a shorter onset latency for the splenic nerve. Acute ADX enhanced the response of both nerves to LPS ( P < 0.005) and reduced the onset latency of the renal nerve ( P < 0.05). PGE2 (2 μg icv) rapidly increased the activity of both nerves but preferentially (magnitude and onset latency) stimulated the renal nerve ( P < 0.05). The magnitude of the splenic nerve response to PGE2 was unaffected by ADX. Unexpectedly, PGE2 was less effective at stimulating renal nerve activity in ADX animals relative to intact controls ( P < 0.05). Pretreatment of ADX rats with a CRF antagonist {[d-Phe12, Nle21,38, Cα-MeLeu37]CRF-(12—41)} reversed this effect such that the renal nerve responded to central PGE2 to a greater extent than the splenic nerve ( P< 0.05), as was the case in non-ADX rats. These data indicate that enhanced sensitivity of central sympathetic pathways does not account for the enhanced SNS responses to LPS in ADX rats. Also, a CRF-related process appears to diminish renal sympathetic outflow in ADX rats.