A functional macrophage migration inhibitory factor promoter polymorphism is associated with reduced diffusing capacity.

Cigarette smoke exposure is the leading modifiable risk factor for chronic obstructive pulmonary disease (COPD); however, the clinical and pathologic consequences of chronic cigarette smoke exposure are variable among smokers. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine implicated in the pathogenesis of COPD. Within the promoter of the MIF gene is a functional polymorphism that regulates MIF expression (-794 CATT5-8 microsatellite repeat) ( rs5844572 ). The role of this polymorphim in mediating disease susceptibility to COPD-related traits remains unknown. We performed a cross-sectional analysis of DNA samples from 641 subjects to analyze MIF-794 CATT5-8 ( rs5844572 ) polymorphism by standard methods. We generated multivariable logistic regression models to determine the risk of low expressing MIF alleles for airflow obstruction [defined by forced expiratory volume in 1 s (FEV1)/forced vital capacity ratio <0.70] and an abnormal diffusion capacity [defined by a diffusion capacity for carbon monoxide (DLCO) percent predicted <80%]. We then used generalized linear models to determine the association of MIF genotypes with FEV1 percent predicted and DLCO percent predicted. The MIF-794 CATT5 allele was associated with an abnormal diffusion capacity in two cohorts [odds ratio (OR): 9.31, 95% confidence interval (CI): 1.97-4.06; and OR: 2.21, 95% CI: 1.03-4.75]. Similarly, the MIF-794 CATT5 allele was associated with a reduced DLCO percentage predicted in these two cohorts: 63.5 vs. 70.0 ( P = 0.0023) and 60.1 vs. 65.4 ( P = 0.059). This study suggests an association between a common genetic polymorphism of an endogenous innate immune gene, MIF, with reduced DLCO, an important measurement of COPD severity.

Performance of the Pooled Cohort atherosclerotic cardiovascular disease risk score in hepatitis C virus-infected persons.

Chronic hepatitis C virus (HCV) infection has been associated with an increased risk for cardiovascular disease (CVD). The recommended Pooled Cohort atherosclerotic cardiovascular disease (ASCVD) risk equation for estimation of 10-year CVD risk has not been validated in HCV-infected populations. We examined the performance of the ASCVD risk score in HCV-infected persons, using the national Electronically Retrieved Cohort of HCV Infected Veterans to derive a cohort of HCV-infected and uninfected subjects without baseline ASCVD, hepatitis B, or HIV infection, and with low-density lipoprotein cholesterol level<190 mg/dL. Performance of the ASCVD risk equation was assessed by Cox proportional hazard regression, C-statistics and Hosmer-Lemeshow statistic. The cohort included 70 490 HCV-infected and 97 766 HCV-uninfected men with mean age of 55 years, 56% White and 29% Black. Incident CVD event rates were similar between the two groups (13.2 and 13.4 events/1000 person-years), with a higher incidence of coronary heart disease events in the HCV-uninfected group and of stroke events in the HCV-infected group. Adjusting for ASCVD risk score, HCV infection was associated with higher risk for an ASCVD event in the subgroup with baseline ASCVD risk ≥7.5% (HR: 1.19, P<.0001). C-statistics were poor in both the HCV-infected and uninfected groups (0.60 and 0.61, respectively). By Hosmer-Lemeshow test, the ASCVD risk equation overestimated risk amongst lower risk patients and underestimated risk amongst higher risk patients in both the HCV-infected and uninfected groups. Further investigation is needed to determine whether a modified equation to accurately predict ASCVD risk in HCV-infected persons is warranted.

Epigenetic Control of Gene Expression in Maize.

Epigenetic gene regulation is important for proper development and gene expression in eukaryotes. Maize has a large and complex genome that includes abundant repetitive sequences which are frequently silenced by epigenetic mechanisms, making it an ideal organism to study epigenetic gene regulation. Epigenetic modifications are chromosome-bound, heritable changes to the genome that do not affect the DNA sequence, and can include DNA methylation, histone modification, and RNA processing. Our appreciation and understanding of epigenetic regulation has grown with the field since its inception ∼65 years ago. Early examples of epigenetic regulation were often associated with transposable elements, starting with McClintock's early work in the 1950s. The observation of other intriguing phenotypes segregating in non-Mendelian ratios in the 1950s provided material for genetic screens that allowed for mechanistic studies of epigenetic regulation that have come to fruition within the past 20 years. The relationship between epigenetic mechanisms and genome organization has become clear with the application of new technologies to characterize maize epigenomes. Our understanding of epigenetic control of gene expression now encompasses the context of genes relative to DNA methylation, chromatin structure, and transposable element content.

Hepatitis C virus treatment and survival in patients with hepatitis C and human immunodeficiency virus co-infection and baseline anaemia.

The impact of pretreatment anaemia on survival in individuals with hepatitis C virus (HCV) and human immunodeficiency virus (HIV) co-infection is not known. Moreover, HCV treatment is offered less frequently to individuals with anaemia, due to haematological side effects of the treatment regimen. This study aimed to determine the effect of HCV treatment on survival among HCV/HIV co-infected individuals with pretreatment anaemia using the Electronically Retrieved Cohort of HCV-Infected Veterans (ERCHIVES). Individuals with HCV/HIV co-infection were included in current analyses. Participants were considered treated if they were prescribed ≥ 4 weeks of HCV treatment. All-cause mortality data were obtained using record linkage. Survival analyses were performed using Cox proportional hazard models. Among 5000 HCV/HIV co-infected individuals, 1671 (33.4%) had pretreatment anaemia. In a follow-up period of up to 7 years (19,500 person-years), individuals with anaemia had significantly higher mortality rate compared with those without anaemia [144.2 (95% CI: 134.5-154.7) vs 47.5 (44.0-51.2) per 1000 person-years, respectively]. Among individuals with anaemia, HCV treatment was associated with significantly lower mortality rate [66.6 (44.3-100.2) vs 149.6 (139.2-160.5) per 1000 person-years, for treated vs untreated, respectively]. Treatment remained associated with substantial survival benefit after taking into account the effect of multiple comorbidities (hazards ratio: 0.34, 95% CI: 0.21-0.62). These data suggest that HCV/HIV co-infected individuals with pretreatment anaemia have significantly higher mortality compared with those without anaemia. HCV treatment is associated with substantial survival benefit in this group. Additional studies are needed to determine strategies to improve HCV treatment rates among this group.

Towards a combined prognostic index for survival in HIV infection: the role of 'non-HIV' biomarkers.

BACKGROUND: As those with HIV infection live longer, 'non-AIDS' condition associated with immunodeficiency and chronic inflammation are more common. We ask whether 'non-HIV' biomarkers improve differentiation of mortality risk among individuals initiating combination antiretroviral therapy (cART). METHODS: Using Poisson models, we analysed data from the Veterans Aging Cohort Study (VACS) on HIV-infected veterans initiating cART between 1 January 1997 and 1 August 2002. Measurements included: HIV biomarkers (CD4 cell count, HIV RNA and AIDS-defining conditions); 'non-HIV' biomarkers (haemoglobin, transaminases, platelets, creatinine, and hepatitis B and C serology); substance abuse or dependence (alcohol or drug); and age. Outcome was all cause mortality. We tested the discrimination (C statistics) of each biomarker group alone and in combination in development and validation data sets, over a range of survival intervals, and adjusting for missing data. RESULTS: Of veterans initiating cART, 9784 (72%) had complete data. Of these, 2566 died. Subjects were middle-aged (median age 45 years), mainly male (98%) and predominantly black (51%). HIV and 'non-HIV' markers were associated with each other (P < 0.0001) and discriminated mortality (C statistics 0.68-0.73); when combined, discrimination improved (P < 0.0001). Discrimination for the VACS Index was greater for shorter survival intervals [30-day C statistic 0.86, 95% confidence interval (CI) 0.80-0.91], but good for intervals of up to 8 years (C statistic 0.73, 95% CI 0.72-0.74). Results were robust to adjustment for missing data. CONCLUSIONS: When added to HIV biomarkers, 'non-HIV' biomarkers improve differentiation of mortality. When evaluated over similar intervals, the VACS Index discriminates as well as other established indices. After further validation, the VACS Index may provide a useful, integrated risk assessment for management and research.

Changing patterns of fetal lung maturity testing.

OBJECTIVE: In our laboratory, a decrease in fetal lung maturity (FLM) testing on amniotic fluid occurred over a 10-year period, and we desired to determine if this was a national phenomenon and, if present, ascertain possible etiologies. STUDY DESIGN: Society of Maternal-Fetal Medicine fellows, both in academic centers and private practice, were surveyed with regard to current usage of FLM testing. RESULT: Of 680 surveys, 417 (61%) responses were returned and 60% noted a decrease in FLM testing (range of reduction--foam stability index 65%, fluorescence polarization 35%, phosphatidyl glycerol 71%, lecithin/sphingomyelin ratio 70%). The most common reason suggested for the decline is that the tests were not needed for patient management. CONCLUSION: Obstetric patterns of FLM testing have declined, principally in near-term pregnancies, and this could adversely affect neonatal outcome.

Co-morbid medical and psychiatric illness and substance abuse in HCV-infected and uninfected veterans.

Comorbidities may affect the decision to treat chronic hepatitis C virus (HCV) infection. We undertook this study to determine the prevalence of these conditions in the HCV-infected persons compared with HCV-uninfected controls. Demographic and comorbidity data were retrieved for HCV-infected and -uninfected subjects from the VA National Patient Care Database using ICD-9 codes. Logistic regression was used to determine the odds of comorbid conditions in the HCV-infected subjects. HCV-uninfected controls were identified matched on age, race/ethnicity and sex. We identified 126 926 HCV-infected subjects and 126 926 controls. The HCV-infected subjects had a higher prevalence of diabetes, anaemia, hypertension, chronic obstructive pulmonary disease (COPD)/asthma, cirrhosis, hepatitis B and cancer, but had a lower prevalence of coronary artery disease and stroke. The prevalence of all psychiatric comorbidities and substance abuse was higher in the HCV-infected subjects. In the HCV-infected persons, the odds of being diagnosed with congestive heart failure, diabetes, anaemia, hypertension, COPD/asthma, cirrhosis, hepatitis B and cancer were higher, but lower for coronary artery disease and stroke. After adjusting for alcohol and drug abuse and dependence, the odds of psychiatric illness were not higher in the HCV-infected persons. The prevalence and patterns of comorbidities in HCV-infected veterans are different from those in HCV-uninfected controls. The association between HCV and psychiatric diagnoses is at least partly attributable to alcohol and drug abuse and dependence. These factors should be taken into account when evaluating patients for treatment and designing new intervention strategies.

Impact of hepatitis C virus infection and other comorbidities on survival in patients on dialysis.

The impact of hepatitis C virus (HCV) and other comorbid conditions upon survival is not well quantified in patients on dialysis. We identified HCV-infected and uninfected persons in the USRDS using claims data in 1997-1998 and followed until September 22, 2002 or death. We used Gray's time-varying coefficients model to examine factors associated with survival. Subjects with a renal transplant were excluded. A total of 5737 HCV-infected and 11 228 HCV-uninfected persons were identified. HCV-infected subjects were younger (mean age 57.8 vs 65.3 years), more likely to be male (57.6%vs 49.6%) and black (54.0%vs 36.4%). They were more likely to have a diagnosis of drug (16.5%vs 4.6%) and alcohol use (14.0%vs 3.1%), and to be human immunodeficiency virus (HIV) co-infected (7.4%vs 1.8%) (all comparisons, P < 0.0005). In an adjusted Gray's time-varying coefficient model, HCV was associated with an increased risk of mortality (P < 0.0005). The hazards were highest at the time of HCV diagnosis and decreased to a stable level 2 years after diagnosis. Other factors associated with increased risk of mortality were (P < 0.0005 unless stated) HIV coinfection; diagnosis of drug use (P = 0.001); coronary artery disease (P = 0.006); stroke; diabetes as the primary cause for renal failure; peripheral vascular disease; depression and presence of anaemia. HCV was associated with higher risk of death in patients on dialysis, even after adjusting for concurrent comorbidities. The risk was highest at the time of HCV diagnosis and stabilized over time. Clinical trials of HCV screening and treatment to reduce mortality in this population are warranted.

Estimating the impact of alcohol consumption on survival for HIV+ individuals.

Alcohol consumption is associated with decreased antiretroviral adherence, and decreased adherence results in poorer outcomes. However the magnitude of alcohol's impact on survival is unknown. Our objective was to use a calibrated and validated simulation of HIV disease to estimate the impact of alcohol on survival. We incorporated clinical data describing the temporal and dose-response relationships between alcohol consumption and adherence in a large observational cohort (N=2,702). Individuals were categorized as nondrinkers (no alcohol consumption), hazardous drinkers (consume > or =5 standard drinks on drinking days), and nonhazardous drinkers (consume <5 standard drinks on drinking days). Our results showed that nonhazardous alcohol consumption decreased survival by more than 1 year if the frequency of consumption was once per week or greater, and by 3.3 years (from 21.7 years to 18.4 years) with daily consumption. Hazardous alcohol consumption decreased overall survival by more than 3 years if frequency of consumption was once per week or greater, and by 6.4 years (From 16.1 years to 9.7 years) with daily consumption. Our results suggest that alcohol is an underappreciated yet modifiable risk factor for poor survival among individuals with HIV.

Identification of amplified clonal T cell populations in the blood of patients with chronic graft-versus-host disease: positive correlation with response to photopheresis.

Chronic graft-versus-host disease (cGVHD) is a multiorgan disorder with skin manifestations resembling scleroderma. Since photopheresis, a treatment that induces an anticlonotypic immune response, has proven to be effective in both cutaneous T cell lymphomas with circulating clonal T cells and in cGVHD, we have searched for circulating clonal T cell populations in patients with cGVHD, and determined whether T cell clonality in the blood is associated with therapeutic response. We screened blood samples from 27 patients after HLA-matched allogeneic bone marrow transplantation (allo-BMT), 10 without cGVHD and 17 with extensive cGVHD, for clonal T cell receptor gamma (TCR gamma) gene rearrangements using fluorescent-based polymerase chain reaction (PCR) and automated high-resolution capillary electrophoresis. Amplified populations of clonal T cells with unique TCR gamma gene rearrangements were found in six of 10 (60%) allo-BMT patients without cGVHD and 13 of 17 (76.5%) allo-BMT patients with cGVHD (P = 0.41), as compared to none of 10 (0%) healthy controls. Twelve patients with cGVHD were treated by photopheresis, and the presence of amplified populations of clonal T cells was found to be associated with a cutaneous response to photopheresis, as eight of eight (100%) clone-positive vs none of four (0%) clone-negative patients experienced a clinically significant cutaneous response to treatment (P = 0.001). Our findings suggest that patients with cGVHD that have detectable expanded clonal T cell populations in their peripheral blood, may be more likely to respond to treatment by photopheresis.

Inhibition of p38 kinase mimics survival signal-linked protection against apoptosis in rat cerebellar granule neurons.

The mitogen-activated protein kinase (MAPK) cascades are thought to be important mediators in the transduction of extracellular signals into cellular responses. The p38 kinase, a member of the MAPK superfamily, is activated by a wide variety of extracellular stimuli and has been implicated in neuronal apoptosis induced by glutamate. In this study we have examined the role of p38 kinase in the potassium deprivation model of apoptosis in rat cerebellar granule neurons (CGN). An increase in p38 kinase activity was observed with a 15-minute potassium deprivation when compared to the basal level. We also found that SB203580 and PD169316, specific p38 kinase inhibitors, significantly attenuated apoptosis in potassium-deprived cells in a dose dependent manner. A decrease in caspase-3 mediated DEVD-MCA, substrate hydrolysis and the appearance of the 120 kDa-spectrin breakdown product in cells treated with SB203580 further suggests that the p38 kinase acts upstream of caspase-3 in the apoptosis cascade. The data provides evidence for an essential role of p38 kinase in mediating apoptotic cell death in CGN and the inhibition of p38 kinase mimics the suppression of apoptosis provided by natural survival signals.

Caspase-mediated calcineurin activation contributes to IL-2 release during T cell activation.

Calcineurin, a Ca(2+)/calmodulin-dependent Ser/Thr phosphatase (protein phosphatase 2B), plays a critical role in IL-2 production during T cell activation. It has been previously reported that IL-2 release in activated Jurkat T requires caspase-like activity (Posmantur et al. (1998) Exp. Cell. Res. 244, 302-309). We report here that the 60-kDa catalytic subunit of calcineurin A (Cn A) was partially cleaved to a 45-kDa form in phytohemagglutinin A (PHA) or phorbol ester + ionomycin (P + I)-activated Jurkat cells. In parallel, proteolytic activation of upstream caspases (caspase-8 and -9) as well as effector caspase-3 was also observed. Cn A cleavage was caspase mediated, since it was inhibitable by pan-caspase inhibitor Cbz-Asp-CH(2)OC(O)-2,6-dichlorobenzene (Z-D-DCB). Cn A cleavage was also observed when purified calcineurin was digested in vitro with caspase-3. Truncated Cn A was associated with enhanced phosphatase activity and reduced calmodulin sensitivity. Furthermore, in PHA or P + I-activated Jurkat cells, dephosphorylation of calcineurin substrate NFATc (a transcription factor known to be involved in transactivation of the IL-2 gene), was also suppressed by Z-D-DCB. Taken together, our results suggest that caspase-mediated cleavage of Cn A contributes to IL-2 production during T cell activation.

An improved fixation technique for fluorescence in situ hybridization for preimplantation genetic diagnosis.

OBJECTIVE: To improve existing preimplantation genetic diagnosis fixation techniques. DESIGN: Prospective randomized in vitro study. SETTING: Academic medical center. PATIENT(S): None. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The intensity and clarity of fluorescence in situ hybridization (FISH) signals and the percentage of successfully fixed blastomeres. RESULT(S): The described fixation technique resulted in 100% fixation and 100% adequate FISH signals. Two conventional techniques resulted in 94% and 87% fixation, and in adequate FISH signals in 81% and 87%, respectively. CONCLUSION(S): This newly developed fixation technique simplifies the process of fixation of blastomeres for preimplantation diagnosis while essentially eliminating the possibility of losing a cell during fixation. It will hopefully allow more IVF programs to offer their patients preimplantation genetic diagnosis using the FISH technique.

Calcium/calmodulin-dependent protein kinase inhibition potentiates thapsigargin-mediated cell death in SH-SY5Y human neuroblastoma cells.

We previously demonstrated a loss in Ca(2+)/Calmodulin-dependent protein kinase (CaM kinase) activity in SH-SY5Y undergoing thapsigargin-mediated apoptosis. To extend that finding we report that CaM kinase inhibition potentiates thapsigargin-mediated cell death. CaM kinase inhibitor KN93 on its own exhibits little toxicity up to 10 mM, as measured by release of lactate dehydrogenase (LDH) into the culture medium. In SH-SY5Y cells pretreated with KN93 and the non-selective protein kinase inhibitor k252a and then treated with 2 mM thapsigargin, loss of viability is significantly greater than in cells treated with thapsigargin alone. Pretreatment with the pan-caspase inhibitor Z-D-DCB prevented the thapsigargin-mediated increase in LDH release. Furthermore, thapsigargin-induced caspase-3-like activation, demonstrated by poly(ADP)ribose polymerase cleavage and pro-caspase-3 processing, was elevated in the presence of KN93.

Effects of major spore-specific DNA binding proteins on Bacillus subtilis sporulation and spore properties.

Sporulation of a Bacillus subtilis strain (termed alpha(-) beta(-)) lacking the majority of the alpha/beta-type small, acid-soluble spore proteins (SASP) that are synthesized in the developing forespore and saturate spore DNA exhibited a number of differences from that of the wild-type strain, including delayed forespore accumulation of dipicolinic acid, overexpression of forespore-specific genes, and delayed expression of at least one mother cell-specific gene turned on late in sporulation, although genes turned on earlier in the mother cell were expressed normally in alpha(-) beta(-) strains. The sporulation defects in alpha(-) beta(-) strains were corrected by synthesis of chromosome-saturating levels of either of two wild-type, alpha/beta-type SASP but not by a mutant SASP that binds DNA poorly. Spores from alpha(-) beta(-) strains also exhibited less glutaraldehyde resistance and slower outgrowth than did wild-type spores, but at least some of these defects in alpha(-) beta(-) spores were abolished by the synthesis of normal levels of alpha/beta-type SASP. These results indicate that alpha/beta-type SASP may well have global effects on gene expression during sporulation and spore outgrowth.

Huntingtin's WW domain partners in Huntington's disease post-mortem brain fulfill genetic criteria for direct involvement in Huntington's disease pathogenesis.

An elongated glutamine tract in mutant huntingtin initiates Huntington's disease (HD) pathogenesis via a novel structural property that displays neuronal selectivity, glutamine progressivity and dominance over the normal protein based on genetic criteria. As this mechanism is likely to involve a deleterious protein interaction, we have assessed the major class of huntingtin interactors comprising three WW domain proteins. These are revealed to be related spliceosome proteins (HYPA/FBP-11 and HYPC) and a transcription factor (HYPB) that implicate huntingtin in mRNA biogenesis. In HD post-mortem brain, specific antibody reagents detect each partner in HD target neurons, in association with disease-related N-terminal morphologic deposits but not with filter trapped insoluble-aggregate. Glutathione S:-transferase partner 'pull-down' assays reveal soluble, aberrantly migrating, forms of full-length mutant huntingtin specific to HD target tissue. Importantly, these novel mutant species exhibit exaggerated WW domain binding that abrogates partner association with other huntingtin isoforms. Thus, each WW domain partner's association with huntingtin fulfills HD genetic criteria, supporting a direct role in pathogenesis. Our findings indicate that modification of mutant huntingtin in target neurons may promote an abnormal interaction with one, or all, of huntingtin's WW domain partners, perhaps altering ribonucleoprotein function with toxic consequences.

Caspase-mediated proteolytic activation of calcineurin in thapsigargin-mediated apoptosis in SH-SY5Y neuroblastoma cells.

We previously demonstrated a loss in calmodulin (CaM)-dependent protein kinase activity in SH-SY5Y cells undergoing thapsigargin-mediated apoptosis, (K. M. McGinnis et al., 1998, J. Biol. Chem. 273, 19993-20000). Here we demonstrate that the large subunit of the CaM-dependent protein phosphatase 2B (calcineurin) is fragmented during SH-SY5Y cell apoptosis to a major fragment of 45 kDa in a caspase inhibitor-sensitive manner. A 45-kDa fragment was also produced when purified calcineurin was digested with recombinant caspase-3. The major cleavage site was identified to be DFGD* G(386)ATAA, which removes the C-terminal CaM-binding and autoinhibitory regions from the catalytic domain. Phosphatase activity increased progressively with caspase-3 digestion, coupled with the eventual loss of CaM-dependency. Calcineurin-mediated dephosphorylation of NFATc was also detected in thapsigargin-treated cells. Last, calcineurin inhibitors FK506 and cypermethrin provided partial protection against thapsigargin-mediated apoptosis, suggesting that calcineurin overactivation contributes to thapsigargin-induced apoptosis.

Development and characterization of antibodies specific to caspase-3-produced alpha II-spectrin 120 kDa breakdown product: marker for neuronal apoptosis.

Alpha II-spectrin (alpha-fodrin) is a demonstrated endogenous substrate for caspase-3 in neurons undergoing unscheduled apoptotic death. We have previously identified the caspase cleavage site that yields the distinctive 120 kDa spectrin breakdown product (SBDP120) as (DSLD(1478)*SVEAL). Here, by using a synthetic peptide (NH(2)-SVEALC) mimicking the neo-N-terminal of SBDP120 as antigen, we report the development of chicken antibodies that specifically recognize the SBDP120 generated by in vitro caspase-3 digestion of bovine alpha-spectrin on Western blot. These anti-SBDP120 antibodies recognize SBDP120 generated by two apoptotic challenges (staurosporine, EGTA) to human neuroblastoma SH-SY5Y cells. Yet they neither react with intact alpha-spectrin nor its other fragments on Western blots. These anti-SBDP120 work equally well in detecting SBDP120 generated in rat cerebellar granule neurons undergoing potassium withdrawal-induced apoptosis. In immunocytochemical studies, these antibodies also specifically stained apoptotic SH-SY5Y or CGN's undergoing apoptosis in a caspase- inhibitor-sensitive manner. These anti-SBDP120s might become powerful markers for apoptotic neurons in various neurological or neurodegenerative conditions in vivo.

Procaspase-3 and poly(ADP)ribose polymerase (PARP) are calpain substrates.

We demonstrate here that both procaspase-3 (32 kDa) and PARP are calpain substrates. In calcium-channel opener maitotoxin-treated cells, a 30 kDa caspase-3 fragment is produced in a time and concentration-dependent manner. Formation of this fragment is prevented by calpain inhibitors but not by the pancaspase inhibitor, carbobenzoxy-Asp-CH(2)OC(O)-2,6-dichlorobenzene (Z-D-DCB) nor the selective proteasome inhibitor lactacystin. In maitotoxin-treated cells, PARP (113 kDa) is also cleaved into a 40 kDa immunoreactive fragment, in a calpain-inhibitor-sensitive manner. Both procaspase-3 and PARP are also cleaved in vitro by purified micro-calpain to a 30 kDa fragment and a 40 kDa fragment, respectively. Finally, we show that staurosporine-mediated caspase-3 activation is interrupted by maitotoxin pretreatment.

Alterations of extracellular calcium elicit selective modes of cell death and protease activation in SH-SY5Y human neuroblastoma cells.

The role of intracellular Ca2+ homeostasis in mechanisms of neuronal cell death and cysteine protease activation was investigated in SH-SY5Y human neuroblastoma cells. Cells were incubated in 2 mM EGTA to lower intracellular Ca2+ or 5 mM CaCl2 to raise it. Cell death and activation of calpain and caspase-3 were measured. Both EGTA and excess CaCl2 elicited cell death. EGTA induced DNA laddering and an increase in caspase-3-like, but not calpain, activity. Pan-caspase inhibitors protected against EGTA-, but not CaCl2-, induced cell death. Conversely, excess Ca2+ elicited necrosis and activated calpain but not caspase-3. Calpain inhibitors did not preserve cell viability. Ca2+ was the death-mediating factor, because restoration of extracellular Ca2+ protected against cell death induced by EGTA and blockade of Ca2+ channels by Ni2+ protected against that induced by high Ca2+. We conclude that the EGTA treatment lowered intracellular Ca2+ and elicited caspase-3-like protease activity, which led to apoptosis. Conversely, excess extracellular Ca2+ entered Ca2+ channels and increased intracellular Ca2+ leading to calpain activation and necrosis. The mode of cell death and protease activation in response to changing Ca2+ were selective and mutually exclusive, demonstrating that these are useful models to individually investigate apoptosis and necrosis.