SHMT2 reduces fatty liver but is necessary for liver inflammation and fibrosis in mice.

Non-alcoholic fatty liver disease is associated with an irregular serine metabolism. Serine hydroxymethyltransferase 2 (SHMT2) is a liver enzyme that breaks down serine into glycine and one-carbon (1C) units critical for liver methylation reactions and overall health. However, the contribution of SHMT2 to hepatic 1C homeostasis and biological functions has yet to be defined in genetically modified animal models. We created a mouse strain with targeted SHMT2 knockout in hepatocytes to investigate this. The absence of SHMT2 increased serine and glycine levels in circulation, decreased liver methylation potential, and increased susceptibility to fatty liver disease. Interestingly, SHMT2-deficient mice developed simultaneous fatty liver, but when fed a diet high in fat, fructose, and cholesterol, they had significantly less inflammation and fibrosis. This study highlights the critical role of SHMT2 in maintaining hepatic 1C homeostasis and its stage-specific functions in the pathogenesis of NAFLD.

Observations on phenomenological changes in Klebsiella Pneumoniae under fluidic stresses.

In the present work, experiments are conducted to understand the consequence of stresses generated by flowing fluid on the bacterial morphology and virulence in microfluidic channels. We consider Klebsiella pneumoniae (KP, a clinical isolate), an ESKAPE pathogen, to be the model bacteria responsible for blood stream infections, bacteremia, including pneumonia, urinary tract infections and more. Four different stress conditions are generated by changing the flow rate and channel geometry subsequently altering the shear rate and stressing time (τ). We observe significant changes in the structural aspects of the stressed bacteria. With an increase in stressing parameters, the viability of the bacterial sample deteriorated. Most importantly, these stressed samples proliferate much more than unstressed samples inside the RAW264.7 murine macrophages. The results shed light on the complex relationship between flow stresses and bacterial virulence. Furthermore, the bacterial samples are challenged with ciprofloxacin to see how they behave under different stress conditions. The observations presented in the present study can be extended to model deadly diseases including bacteremia using organ-on-a-chip technology and to understand bacterial pathogenicity under realistic environments.

Intermittent fasting induced ketogenesis inhibits mouse epithelial ovarian cancer by promoting antitumor T cell response.

In various cancer models, dietary interventions have been shown to inhibit tumor growth, improve anticancer drug efficacy, and enhance immunity, but no such evidence exists for epithelial ovarian cancer (EOC), the most lethal gynecologic cancer. The anticancer immune responses induced by 16-h intermittent fasting (IF) were studied in mice with EOC. IF consistently reduced metabolic growth factors and cytokines that stimulate tumor growth, creating a tumor-hostile environment. Immune profiling showed that IF dramatically alters anti-cancer immunity by increasing CD4+ and CD8+ cells, Th1 and cytotoxic responses, and metabolic fitness. ß-hydroxy butyrate (BHB), a bioactive metabolite produced by IF, partially imitates its anticancer effects by inducing CD8+ effector function. In a direct comparison, IF outperformed exogenous BHB treatment in survival and anti-tumor immune response, probably due to increased ketogenesis. Thus, IF and one of its metabolic mediators BHB suppress EOC growth and sustain a potent anti-tumor T cell response.

An early glycolysis burst in microglia regulates mitochondrial dysfunction in oligodendrocytes under neuroinflammation.

Metabolism and energy processes governing oligodendrocyte function during neuroinflammatory disease are of great interest. However, how varied cellular environments affect oligodendrocyte activity during neuroinflammation is unknown. We demonstrate that activated microglial energy metabolism controls oligodendrocyte mitochondrial respiration and activity. Lipopolysaccharide/interferon gamma promote glycolysis and decrease mitochondrial respiration and myelin protein synthesis in rat brain glial cells. Enriched microglia showed an early burst in glycolysis. In microglia-conditioned medium, oligodendrocytes did not respire and expressed less myelin. SCENITH revealed metabolic derangement in microglia and O4-positive oligodendrocytes in endotoxemia and experimental autoimmune encephalitogenic models. The early burst of glycolysis in microglia was mediated by PDPK1 and protein kinase B/AKT signaling. We found that microglia-produced NO and itaconate, a tricarboxylic acid bifurcated metabolite, reduced mitochondrial respiration in oligodendrocytes. During inflammation, we discovered a signaling pathway in microglia that could be used as a therapeutic target to restore mitochondrial function in oligodendrocytes and induce remyelination.

Intermittent Fasting induced ketogenesis inhibits mouse epithelial ovarian tumors by promoting anti-tumor T cell response.

Epithelial Ovarian Cancer (EOC) is the most lethal gynecologic cancer with limited genetic alterations identified that can be therapeutically targeted. In tumor bearing mice, short-term fasting, fasting mimicking diet and calorie restriction enhance the activity of antineoplastic treatment by modulating systemic metabolism and boosting anti-tumor immunity. We tested the outcome of sixteen-hour intermittent fasting (IF) on mouse EOC progression with focus on fasting driven antitumor immune responses. IF resulted in consistent decrease of tumor promoting metabolic growth factors and cytokines, recapitulating changes that creates a tumor antagonizing environment. Immune profiling revealed that IF profoundly reshapes anti-cancer immunity by inducing increase in CD4+ and CD8+ cells, paralleled by enhanced antitumor Th1 and cytotoxic responses, by enhancing their metabolic fitness. Metabolic studies revealed that IF generated bioactive metabolite BHB which can be a potential substitute for simulating the antitumor benefits of IF. However, in a direct comparison, IF surpassed exogenous BHB therapy in improving survival and activating anti-tumor immune response. Thus, our data provides strong evidence for IF and its metabolic mediator BHB for ameliorating EOC progression and as a viable approach in maintaining and sustaining an effective anti-tumor T cell response.

Caveolin-1 peptide regulates p53-microRNA-34a feedback in fibrotic lung fibroblasts.

Idiopathic pulmonary fibrosis (IPF) is a life-threatening disease resulting from dysregulated repair responses to lung injury. Excessive extracellular matrix deposition by expanding myofibroblasts and fibrotic lung fibroblasts (fLfs) has been implicated in the pathogenesis of PF, including IPF. We explored fLfs' microRNA-34a (miR-34a) expression from IPF tissues. Basal miR-34a levels were decreased with reduced binding of p53 to the promoter DNA and 3'UTR mRNA sequences. Overexpression of miR-34a in fLfs increased p53, PAI-1, and reduced pro-fibrogenic markers. The regulatory effects of miR-34a were altered by modifying the p53 expression. Precursor-miR-34a lung transduction reduced bleomycin-induced PF in wild-type mice. fLfs treated with caveolin-1 scaffolding domain peptide (CSP) or its fragment, CSP7, restored miR-34a, p53, and PAI-1. CSP/CSP7 reduced PDGFR-ß and pro-fibrogenic markers, which was abolished in fLfs following blockade of miR-34a expression. These peptides failed to resolve PF in mice lacking miR-34a in fLfs, indicating miR-34a-p53-feedback induction required for anti-fibrotic effects.

Divergent Metabolic Effects of Metformin Merge to Enhance Eicosapentaenoic Acid Metabolism and Inhibit Ovarian Cancer In Vivo.

Metformin is being actively repurposed for the treatment of gynecologic malignancies including ovarian cancer. We investigated if metformin induces analogous metabolic changes across ovarian cancer cells. Functional metabolic analysis showed metformin caused an immediate and sustained decrease in oxygen consumption while increasing glycolysis across A2780, C200, and SKOV3ip cell lines. Untargeted metabolomics showed metformin to have differential effects on glycolysis and TCA cycle metabolites, while consistent increased fatty acid oxidation intermediates were observed across the three cell lines. Metabolite set enrichment analysis showed alpha-linolenic/linoleic acid metabolism as being most upregulated. Downstream mediators of the alpha-linolenic/linoleic acid metabolism, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were abundant in all three cell lines. EPA was more effective in inhibiting SKOV3 and CaOV3 xenografts, which correlated with inhibition of inflammatory markers and indicated a role for EPA-derived specialized pro-resolving mediators such as Resolvin E1. Thus, modulation of the metabolism of omega-3 fatty acids and their anti-inflammatory signaling molecules appears to be one of the common mechanisms of metformin's antitumor activity. The distinct metabolic signature of the tumors may indicate metformin response and aid the preclinical and clinical interpretation of metformin therapy in ovarian and other cancers.

Caveolin-1-derived peptide limits development of pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease with a median 5-year survival of ~20%. Current U.S. Food and Drug Administration-approved pharmacotherapies slow progression of IPF, providing hope that even more effective treatments can be developed. Alveolar epithelial progenitor type II cell (AEC) apoptosis and proliferation, and accumulation of activated myofibroblasts or fibrotic lung fibroblasts (fLfs) contribute to the progression of IPF. Full-length caveolin-1 scaffolding domain peptide (CSP; amino acids 82 to 101 of Cav1: DGIWKASFTTFTVTKYWFYR) inhibits AEC apoptosis and fLf activation and expansion and attenuates PF in bleomycin (BLM)-induced lung injury in mice. Like full-length CSP, a seven-amino acid deletion fragment of CSP, CSP7 (FTTFTVT), demonstrated antifibrotic effects in murine models of lung fibrosis. When CSP7 was administered during the fibrotic phase in three preclinical models [single-dose BLM, repeated-dose BLM, and adenovirus expressing constitutively active transforming growth factor-ß1 (Ad-TGF-ß1)-induced established PF], CSP7 reduced extracellular matrix (ECM) markers characteristic of PF, increased AEC survival, and improved lung function. CSP7 is amenable to both systemic (intraperitoneal) or direct lung delivery in a nebulized or dry powder form. Furthermore, CSP7 treatment of end-stage human IPF lung tissue explants attenuated ECM production and promoted AEC survival. Ames testing for mutagenicity and in vitro human peripheral blood lymphocyte and in vivo mouse micronucleus transformation assays indicated that CSP7 is not carcinogenic. Together, these findings support the further development of CSP7 as an antifibrotic treatment for patients with IPF or other interstitial lung diseases.

p53 Expression in Lung Fibroblasts Is Linked to Mitigation of Fibrotic Lung Remodeling.

Idiopathic pulmonary fibrosis (IPF) is a debilitating, incurable, and life-threatening disease. A cardinal feature of the pathogenesis of IPF is excessive extracellular matrix deposition attributable to proliferation of activated fibrotic lung fibroblasts (fLfs). To assess the underlying mechanism, we analyzed the status of the tumor suppressor protein p53 in fLfs from the lungs of IPF patients or mice with bleomycin-induced established PF. We report that basal expression of p53 is markedly reduced in fLfs. Forced expression of caveolin-1 in fLfs increased basal p53 and reduced profibrogenic proteins, including collagen-1. Transduction of fLfs with adenovirus expressing p53 reduced expression of these proteins. Conversely, inhibition of baseline p53 in control lung fibroblasts from lung tissues increased profibrogenic protein expression. Lung transduction of adenovirus expressing p53 reduced bleomycin-induced PF in wild-type or caveolin-1-deficient mice. Furthermore, treatment of fLfs or fibrotic lung tissues with caveolin-1 scaffolding domain peptide (CSP) or its fragment, CSP7, restored p53 and reduced profibrogenic proteins. Treatment of wild-type mice with i.p. CSP or CSP7 resolved bleomycin-induced PF. These peptides failed to resolve PF in inducible conditional knockout mice lacking p53 in fLfs, indicating the induction of baseline fLf p53 as the basis of the antifibrotic effects.

Regulation of p53-mediated changes in the uPA-fibrinolytic system and in lung injury by loss of surfactant protein C expression in alveolar epithelial cells.

Pulmonary surfactant protein C (SP-C) expression by type II alveolar epithelial cells (AECs) is markedly reduced in diverse types of lung injuries and is often associated with AEC apoptosis. It is unclear whether loss of SP-C contributes to the increased p53 and urokinase-type plasminogen activator (uPA) system cross-talk and apoptosis of AECs. Therefore, we inhibited SP-C expression in human and murine AECs using lentivirus vector expressing shRNA and tested p53 and downstream changes in the uPA-fibrinolytic system. Inhibition of SP-C expression in AECs induced p53 and activated caspase-3, indicating AEC apoptosis. We also found that bleomycin or cigarette smoke exposure failed to inhibit SP-C expression or apoptosis in AECs in p53- and plasminogen activator inhibitor-1 (PAI-1)-deficient mice. Depletion of SP-C expression by lentiviral SP-C shRNA in PAI-1-deficient mice failed to induce p53 or apoptosis in AECs, whereas it increased both AEC p53 and apoptosis in wild-type and uPA-deficient mice. SP-C inhibition in AECs also increased in CXCL1 and CXCL2 and their receptor CXCR2 as well as ICAM-1 expression, which is indicative of a proinflammatory response. Overexpression of p53-binding 3'-UTR sequences in AECs inhibited PAI-1 induction while maintaining uPA and uPAR protein and mRNA expression. Furthermore, caveolin-1 expression and phosphorylation were increased in AECs, indicating an intricate link between caveolin-1 and Src kinase-mediated cell signaling and AEC apoptosis due to loss of SP-C expression through p53 and uPA system-mediated cross-talk. The role of uPA, PAI-1, and p53 in the regulation of AEC apoptosis after injury was also determined in knockout mice.

p53 and miR-34a Feedback Promotes Lung Epithelial Injury and Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal interstitial lung disease. The pathogenesis of interstitial lung diseases, including its most common form, IPF, remains poorly understood. Alveolar epithelial cell (AEC) apoptosis, proliferation, and accumulation of myofibroblasts and extracellular matrix deposition results in progressive loss of lung function in IPF. We found induction of tumor suppressor protein, p53, and apoptosis with suppression of urokinase-type plasminogen activator (uPA) and the uPA receptor in AECs from the lungs of IPF patients, and in mice with bleomycin, cigarette smoke, silica, or sepsis-induced lung injury. Treatment with the caveolin-1 scaffolding domain peptide (CSP) reversed these effects. Consistent with induction of p53, AECs from IPF lungs or mice with diverse types of lung injuries showed increased p53 acetylation and miR-34a expression with reduction in Sirt1. This was significantly reduced after treatment of wild-type mice with CSP, and uPA-deficient mice were unresponsive. Bleomycin failed to induce miR-34a in p53- or plasminogen activator inhibitor-1 (PAI-1)-deficient mice. CSP-mediated inhibition of miR-34a restored Sirt1, suppressed p53 acetylation and apoptosis in injured AECs, and prevented pulmonary fibrosis (PF). AEC-specific suppression of miR-34a inhibited bleomycin-induced p53, PAI-1, and apoptosis and prevented PF, whereas overexpression of precursor-miR-34a increased p53, PAI-1, and apoptosis in AECs of mice unexposed to bleomycin. Our study validates p53-miR-34a feedback as a potential therapeutic target in PF.

p53- and PAI-1-mediated induction of C-X-C chemokines and CXCR2: importance in pulmonary inflammation due to cigarette smoke exposure.

We previously demonstrated that tumor suppressor protein p53 augments plasminogen activator inhibitor-1 (PAI-1) expression in alveolar epithelial cells (AECs) during chronic cigarette smoke (CS) exposure-induced lung injury. Chronic lung inflammation with elevated p53 and PAI-1 expression in AECs and increased susceptibility to and exacerbation of respiratory infections are all associated with chronic obstructive pulmonary disease (COPD). We recently demonstrated that preventing p53 from binding to the endogenous PAI-1 mRNA in AECs by either suppressing p53 expression or blockading p53 interactions with the PAI-1 mRNA mitigates apoptosis and lung injury. Within this context, we now show increased expression of the C-X-C chemokines (CXCL1 and CXCL2) and their receptor CXCR2, and the intercellular cellular adhesion molecule-1 (ICAM-1), in the lung tissues of patients with COPD. We also found a similar increase in lung tissues and AECs from wild-type (WT) mice exposed to passive CS for 20 wk and in primary AECs treated with CS extract in vitro. Interestingly, passive CS exposure of mice lacking either p53 or PAI-1 expression resisted an increase in CXCL1, CXCL2, CXCR2, and ICAM-1. Furthermore, inhibition of p53-mediated induction of PAI-1 expression by treatment of WT mice exposed to passive CS with caveolin-1 scaffolding domain peptide reduced CXCL1, CXCL2, and CXCR2 levels and lung inflammation. Our study reveals that p53-mediated induction of PAI-1 expression due to chronic CS exposure exacerbates lung inflammation through elaboration of CXCL1, CXCL2, and CXCR2. We further provide evidence that targeting this pathway mitigates lung injury associated with chronic CS exposure.

Antibody and inflammatory response-mediated severity of pandemic 2009 (pH1N1) influenza virus.

Influenza A virus causes significant morbidity and mortality each year worldwide due to antigenic drift, punctuated by infrequent pandemics following antigenic shift. H1N1 subtype of pandemic 2009 (pH1N1) influenza virus lineages has continued to circulate in humans and raised severe concerns about its pandemic developments. The pathogenesis of the disease and its progression as post-infectious sequelae is not well understood. Moderate inflammatory response protects against the ill effects and hyper-inflammatory response promotes the pathogenesis in disease progression. Samples were screened by RT-PCR and classified in pandemic 2009 (pH1N1), Influenza A virus infected patient. Further antibody titer was analyzed by hemagglutination inhibition assay and cytokine/chemokine response by Cytometric bead array assy. Screening of 216 patients shows 63 were belongs to pH1N1 influenza virus infection and 47 were Influenza A virus infected and 106 samples were negative for these viruses, were used as a disease control. Apart from that 100 samples were taken for healthy control. Lower antibody titer was found in patient infected with pH1N1/Influenza A virus and expression of cytokines (IL-6, IL-8, and IL-10) and chemokine MCP-1 was higher in patient infected with pH1N1 compare to healthy/disease control however there was no significant difference observed in the expression of pro-inflammatory cytokines TNF-α and antiviral cytokine IFN-γ in pH1N1 influenza virus infected patients.

Fine-mapping loss of gene architecture at the CDKN2B (p15INK4b), CDKN2A (p14ARF, p16INK4a), and MTAP genes in head and neck squamous cell carcinoma.

OBJECTIVE: To identify the extent and the smallest region of loss for CDKN2B(INK4b), CDKN2A(ARF,INK4a), and MTAP. Homozygous deletions of human chromosome 9p21 occur frequently in malignant cell lines and are common in squamous cell carcinoma of the head and neck (HNSCC). This complex region encodes the tumor suppressor genes cyclin-dependent kinase 2B (CDKN2B) (p15(INK4b)) and CDKN2A (p14(ARF), p16(INK4a)) and the housekeeping gene methylthioadenosine phosphorylase (MTAP). DESIGN: A targeted probe panel designed to finely map the region of 9p21 loss comprised 3 probes for CDKN2B(INK4b), 7 for CDKN2A(ARF, INK4a), and 3 for MTAP and was interrogated using the multiplex ligation-dependent probe amplification assay (MLPA). The MLPA genomic copy number alterations for CDKN2A were validated using real-time polymerase chain reaction. SUBJECTS: Six HNSCC primary (A) and recurrent or metastatic (B) cell lines were examined: UMSCC-11A/11B, UMSCC-17A/17B, and UMSCC-81A/81B. RESULTS: Cell line UMSCC-11B retained all 9p loci tested in the region. Cell lines UMSCC-17A/B indicated homozygous deletion of CDKN2A(ARF, INK4a) starting at p16(INK4) exon 1alpha to include exons 2 and 3. Homozygous loss was indicated for CDKN2B(INK4b) and CDKN2A(ARF,INK4a) in UMSCC-11A, and UMSCC-81A. Cell line UMSCC-81B indicated retention of all 9p loci except for exon 1alpha (p16(INK4a)). Selective loss of the 3' end of MTAP was observed in UMSCC-11A. Genomic alterations by fine-mapping MLPA were validated at the DNA level for CDKN2A. CONCLUSIONS: We identified exon 1alpha (p16(INK4a)) as the smallest region of loss in the CDKN2A(ARF, INK4a) gene. The frequency and precise loss of CDKN2B(INK4b), CDKN2A(ARF, INK4a), and MTAP in the prognosis of 9p21-deleted HNSCC may provide impetus for use of these targets as therapeutic biomarkers in head and neck cancer.

High-resolution mapping of molecular events associated with immortalization, transformation, and progression to breast cancer in the MCF10 model.

BACKGROUND: A comprehensive and consistent picture of the genetic changes that underlie breast cancer initiation, development, and progression remains unresolved. The MCF10 series of cell lines represents many steps in that progression. We performed high resolution mapping of the MCF10 series of cell lines to identify specific gene targets to elucidate the molecular correlates of immortalization, development, and progression of breast cancer at the level of individual genes. DESIGN: We evaluated the initial untransformed outgrowths (MCF-10MS and MCF-10A) with six transformed cell lines with benign proliferations (MCF-10AT1, MCF-10AT1kcl2), carcinoma in situ (MCF-10CA1h cl13), and invasive carcinoma (MCF-10CA1h cl2, MCF-10CA1a cl1, MCF-10CA1d cl1). Losses and gains of loci at 112 unique human genome sites were interrogated using the multiplex ligation-dependent probe amplification assay (MLPA). RESULTS: Cytogenetic alterations in the four benign progenitors that persisted in the CIS and invasive cell lines corresponded to gains and losses of genes by MLPA. MCF-10MS had only normal gene copies. The untransformed MCF-10A had cytogenetic gain of 5q13-qter with corresponding gains of the IL3, IL4 and IL12B genes at 5q31-q33; gain of distal 19q12-qter was reflected in gains in KLK3 and BAX gene loci at 19q13-q13.4. The observed genic gain of cMYC at 8q24.12 was not indicated by cytogenetics. The apparently balanced t(3;9) component of the t(3;9)(p13;p22)t(3;5)(p26;q31) resulted in complete loss of the CDKN2A and CDKN2B genes at 9p21. Additional clonal cytogenetic changes in the DCIS cell line (MCF-10A1h cl13) involving chromosomes 1, 3 and 10 persisted in the invasive progeny, with gain of corresponding genes at 1p13 (BCAR2, BCAR3, NRAS, TGFB2), at 3p12-13 (IL12A), and 3q21-27 (MME, PIK3CA, BCL6). CONCLUSIONS: Our study adopted a comprehensive exploration of genetic changes using high resolution molecular probes applied to the MCF10 family of cell lines to identify individual genes in a continuum starting from normal breast epithelial cells and progressing through immortalization, transformation and invasive malignancy. Homozygous loss of CDKN2A and CDKN2B genes and gain of MYC were initiating immortalization events. Transformation and progression to malignancy event were marked by gains of IL13, VEGF, HRAS, TRAF2, and BCAS2, IL12A, and MME, respectively.

Identification of individual genes altered in squamous cell carcinoma of the vulva.

Chromosome rearrangements in squamous cell carcinoma of the vulva (SCV) have indicated common consistent regions of loss and gain. The overall aim of our research was to define and characterize individual genes that underlie the pathogenesis of SCV. Thirteen cell lines from 12 SCV patients were evaluated for loss and gain of 122 genes distributed throughout the genome. Individual genes were analyzed for genetic alterations using a novel genomewide strategy, the multiplex ligation-dependent probe amplification assay. Our candidate gene approach identified several altered loci. Most frequent was the loss of 1 copy of TMSB10, observed in 11 of 12 SCV patients, followed by loss of CTNNB1 and BCL2, which occurred in 7 of 12 patients. Frequent gains/amplifications included CCND1, observed in 8 of 12 patients, and IL12A, in 7 of the 12 patients. Loss and gain of specific genes observed in our study were generally concordant with the results of previous studies of cytogenetics and CGH utilizing the same SCV cell lines. Genetic alterations are hallmarks of tumorigenesis, and there is wide agreement that recurrent altered genomic loci contain genes important for tumor development and progression. Understanding the interplay of cancer genes and the pathways they utilize can lead to the detection of novel molecular targets in the diagnosis, prognosis, and treatment of SCV.

Molecular mechanisms of reduced sarcoplasmic reticulum Ca(2+) uptake in human failing left ventricular myocardium.

BACKGROUND: Human failing heart due to idiopathic dilated cardiomyopathy is associated with decreased sarcoplasmic reticulum Ca(2+) uptake. However, it is unknown as to which mechanism leads to this abnormality. METHODS: Immunodetectable sarcoplasmic reticulum proteins (phospholamban [PLB], phosphorylated PLB at serine-16 or threonine-17, calsequestrin and Ca(2+)-ATPase levels), the activities of Ca(2+)-calmodulin-dependent protein kinase and protein phosphatase and Ca(2+) uptake at varying Ca(2+) concentrations were determined in left ventricular specimens from the same 7 failing hearts (ejection fraction 20 +/- 2%) due to idiopathic dilated cardiomyopathy and 5 non-failing explanted control donor hearts. RESULTS: In failing hearts, compared with control donors, decreased maximal velocity and affinity of Ca(2+) uptake for Ca(2+) were found to be associated with reduced expression levels of Ca(2+)-adenosine triphosphatase (ATPase), PLB and phosphorylated PLB at serine-16, but not of calsequestrin and phosphorylated PLB at threonine-17. In contrast, protein phosphatase activity increased significantly and the activity and protein expression level of the delta isoform of Ca(2+)-calmodulin-dependent protein kinase remained unchanged in failing hearts compared with control donors. CONCLUSIONS: The impaired maximal velocity of sarcoplasmic reticulum Ca(2+) uptake may be due in part to reduced protein expression level of Ca(2+)-ATPase, whereas the reduced affinity may be due in part to the reduced ratio of Ca(2+)-ATPase to PLB and reduced PLB phosphorylation at serine-16 in failing hearts. The latter abnormality may be due in part to increased protein phosphatase activity. These results suggest that selective enhancement of Ca(2+) uptake into the sarcoplasmic reticulum by pharmaceutical agents, or by molecular tools that inhibit phosphatase activity, would be a valuable therapeutic approach for treating, or at least retarding, the process of heart failure.