Bax inhibitor-1 (BI-1) is an evolutionarily conserved endoplasmic reticulum (ER) protein that suppresses cell death in both animal and plant cells. We characterized mice in which the bi-1 gene was ablated. Cells from BI-1-deficient mice, including fibroblasts, hepatocytes, and neurons, display selective hypersensitivity to apoptosis induced by ER stress agents (thapsigargin, tunicamycin, brefeldin A), but not to stimulators of mitochondrial or TNF/Fas-death receptor apoptosis pathways. Conversely, BI-1 overexpression protects against apoptosis induced by ER stress. BI-1-mediated protection from apoptosis induced by ER stress correlated with inhibition of Bax activation and translocation to mitochondria, preservation of mitochondrial membrane potential, and suppression of caspase activation. BI-1 overexpression also reduces releasable Ca(2+) from the ER. In vivo, bi-1(-/-) mice exhibit increased sensitivity to tissue damage induced by stimuli that trigger ER stress, including stroke and tunicamycin injection. Thus, BI-1 regulates a cell death pathway important for cytopreservation during ER stress.
Purpose: Caspase-14 is unique among caspase family proteases in that its proteolytic processing has been principally associated with epithelial cell differentiation rather than apoptosis or inflammation.We investigated caspase-14 expression in several types of human epithelial malignancy by immunohistochemistry, correlating results with stage, histologic grade, and patient survival. Experimental Design: Tumor-associated alterations in caspase-14 expression were observed for cervical, ovarian, breast, gastric, and colon cancers. Results: In cervical (n = 445), ovarian (n = 91), and colon (n = 106) specimens, expression of caspase-14 was significantly reduced in cancers compared with normal epithelium. Decreases in caspase-14 immunopositivity correlated with the histologic progression of cervical cancer (P < 0.0001, ANOVA). In localized gastric cancers, caspase-14 immunostaining was significantly lower in poorly differentiated tumors compared with well-differentiated tumors (P = 0.02, Pearson's m 2 analysis). Lower caspase-14 expression was associated with advanced clinical stage in ovarian cancer (P = 0.04, ANOVA) and with shorter overall survival among ovarian cancer patients with serous tumors (n = 62) in both univariate (P = 0.005) and multivariate (P = 0.03) analysis. Lower caspase-14 expression correlated with shorter overall survival among patients with T 3 N 0 M 0 stage gastric cancers (n = 94; P = 0.006, log-rank test). In contrast to cervical, ovarian, and colon cancers, caspase-14 expression was increased in ductal carcinoma in situ and invasive cancers compared with normal mammary epithelium (P = 0.001, t test). Conclusions: The findings reveal tumor-specific alterations in caspase-14 expression and suggest that differences in its expression may define subsets of epithelial cancers with distinct clinical behaviors.
Obesity and diabetes, termed "diabesity," are serious health problems that are increasing in frequency. However, the molecular mechanisms and neuronal regulation of these metabolic disorders are not fully understood. We show here that Shp2, a widely expressed Src homology 2-containing Tyr phosphatase, plays a critical role in the adult brain to control food intake, energy balance, and metabolism. Mice with a neuron-specific, conditional Shp2 deletion were generated by crossing a pan-neuronal Cre-line (CRE3) with Shp2 flox/flox mice. These congenic mice, CRE3/ Shp2-KO, developed obesity and diabetes and the associated pathophysiological complications that resemble those encountered in humans, including hyperglycemia, hyperinsulinemia, hyperleptinemia, insulin and leptin resistance, vasculitis, diabetic nephropathy, urinary bladder infections, prostatitis, gastric paresis, and impaired spermatogenesis. This mouse model may help to elucidate the molecular mechanisms that lead to the development of diabesity in humans and provide a tool to study the in vivo complications of uncontrolled diabetes. (Am J Pathol
BackgroundAcute brain injury is an important health problem. Given the critical position of caspase 8 at the crossroads of cell death pathways, we generated a new viable mouse line (Ncasp8 −/−), in which the gene encoding caspase 8 was selectively deleted in neurons by cre-lox system.Methodology/Principal FindingsCaspase 8 deletion reduced rates of neuronal cell death in primary neuronal cultures and in whole brain organotypic coronal slice cultures prepared from 4 and 8 month old mice and cultivated up to 14 days in vitro. Treatments of cultures with recombinant murine TNFα (100 ng/ml) or TRAIL (250 ng/mL) plus cyclohexamide significantly protected neurons against cell death induced by these apoptosis-inducing ligands. A protective role of caspase 8 deletion in vivo was also demonstrated using a controlled cortical impact (CCI) model of traumatic brain injury (TBI) and seizure-induced brain injury caused by kainic acid (KA). Morphometric analyses were performed using digital imaging in conjunction with image analysis algorithms. By employing virtual images of hundreds of brain sections, we were able to perform quantitative morphometry of histological and immunohistochemical staining data in an unbiased manner. In the TBI model, homozygous deletion of caspase 8 resulted in reduced lesion volumes, improved post-injury motor performance, superior learning and memory retention, decreased apoptosis, diminished proteolytic processing of caspases and caspase substrates, and less neuronal degeneration, compared to wild type, homozygous cre, and caspase 8-floxed control mice. In the KA model, Ncasp8 −/− mice demonstrated superior survival, reduced seizure severity, less apoptosis, and reduced caspase 3 processing. Uninjured aged knockout mice showed improved learning and memory, implicating a possible role for caspase 8 in cognitive decline with aging.ConclusionsNeuron-specific deletion of caspase 8 reduces brain damage and improves post-traumatic functional outcomes, suggesting an important role for this caspase in pathophysiology of acute brain trauma.
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