No abstract

SUMMARY Chronic hypoxia in the presence of high glucose leads to progressive acidosis of cardiac myocytes in culture. The condition parallels myocardial ischemia in vivo, where ischemic tissue becomes rapidly hypoxic and acidotic. Cardiac myocytes are resistant to chronic hypoxia at neutral pH but undergo extensive death when the extracellular pH (pH[o]) drops below 6.5. A microarray analysis of 20 000 genes (cDNAs and expressed sequence tags)screened with cDNAs from aerobic and hypoxic cardiac myocytes identified>100 genes that were induced by >2-fold and ∼20 genes that were induced by >5-fold. One of the most strongly induced transcripts was identified as the gene encoding the pro-apoptotic Bcl-2 family member BNIP3. Northern and western blot analyses confirmed that BNIP3 was induced by 12-fold(mRNA) and 6-fold (protein) during 24 h of hypoxia. BNIP3 protein, but not the mRNA, accumulated 3.5-fold more rapidly under hypoxia–acidosis. Cell fractionation experiments indicated that BNIP3 was loosely bound to mitochondria under conditions of neutral hypoxia but was translocated into the membrane when the myocytes were acidotic. Translocation of BNIP3 coincided with opening of the mitochondrial permeability pore (MPTP). Paradoxically,mitochondrial pore opening did not promote caspase activation, and broad-range caspase inhibitors do not block this cell death pathway. The pathway was blocked by antisense BNIP3 oligonucleotides and MPTP inhibitors. Therefore,cardiac myocyte death during hypoxia–acidosis involves two distinct steps: (1) hypoxia activates transcription of the death-promoting BNIP3 gene through a hypoxia-inducible factor-1 (HIF-1) site in the promoter and (2) acidosis activates BNIP3 by promoting membrane translocation. This is an atypical programmed death pathway involving a combination of the features of apoptosis and necrosis. In this article, we will review the evidence for this unique pathway of cell death and discuss its relevance to ischemic heart disease. The article also contains new evidence that chronic hypoxia at neutral pH does not promote apoptosis or activate caspases in neonatal cardiac myocytes.

Chicken body weight is an economically important trait and great genetic progress has been accomplished in genetic selective for body weight. To identify genes and chromosome regions associated with body weight, we performed a genome-wide association study using the chicken 60 k SNP panel in a chicken F2 resource population derived from the cross between Silky Fowl and White Plymouth Rock. A total of 26 SNP effects involving 9 different SNP markers reached 5% Bonferroni genome-wide significance. A chicken chromosome 4 (GGA4) region approximately 8.6 Mb in length (71.6–80.2 Mb) had a large number of significant SNP effects for late growth during weeks 7–12. The LIM domain-binding factor 2 (LDB2) gene in this region had the strongest association with body weight for weeks 7–12 and with average daily gain for weeks 6–12. This GGA4 region was previously reported to contain body weight QTL. GGA1 and GGA18 had three SNP effects on body weight with genome-wide significance. Some of the SNP effects with the significance of “suggestive linkage” overlapped with previously reported results.

Background: Ionizing radiation (IR) therapy is a primary treatment for glioblastoma multiforme (GBM), a common and devastating brain tumor in humans. IR has been shown to induce PI3K-Akt activation in many cell types, and activation of the PI3K-Akt signaling pathway has been correlated with radioresistance.

The preparation of two-dimensional covalent organic frameworks (2D COFs) with large crystalline domains and controlled morphology is necessary for realizing the full potential of their atomically precise structures and uniform, tailorable porosity. Currently 2D COF syntheses are developed empirically, and most materials are isolated as insoluble and unprocessable powders with typical crystalline domain sizes smaller than 50 nm. Little is known about their nucleation and growth processes, which involve a combination of covalent bond formation, degenerate bond exchange, and noncovalent stacking processes. A deeper understanding of the chemical processes that lead to COF polymerization and crystallization is key to achieving improved materials quality and control. Here, we report a kinetic Monte Carlo (KMC) model that describes the formation of a prototypical boronate-ester linked 2D COF known as COF-5 from its 2,3,6,7,10,11-hexahydroxytriphenylene and 1,4-phenylene bis(boronic acid) monomers in solution. The key rate parameters for the KMC model were derived from experimental measurements when possible and complemented with reaction pathway analyses, molecular dynamics simulations, and binding free-energy calculations. The essential features of experimentally measured COF-5 growth kinetics are reproduced well by the KMC simulations. In particular, the simulations successfully captured a nucleation process followed by a subsequent growth process. The nucleating species are found to be relatively small, multilayer structures that form through multiple pathways. During the growth of COF-5, extensions in the lateral (in-plane) and vertical (stacking) directions are both seen to be linear with respect to time and are dominated by monomer addition and oligomer association, respectively. Finally, we show that the experimental observations of increased average crystallite size with the addition of water are modeled accurately by the simulations. These results will inform the rational development of 2D COF polymerizations by controlling the rate of nucleation, thereby increasing their materials quality.

The human androgen receptor (AR) is considered as a master regulator in the development and progression of prostate cancer (PCa). As resistance to clinically used anti-AR drugs remains a major challenge for the treatment of advanced PCa, there is a pressing need for new anti-AR therapeutic avenues. In this study, we identified a binding site on the DNA binding domain (DBD) of the receptor and utilized virtual screening to discover a set of micromolar hits for the target. Through further exploration of the most potent hit (1), a structural analogue (6) was identified demonstrating 10-fold improved anti-AR potency. Further optimization resulted in a more potent synthetic analogue (25) with anti-AR potency comparable to a newly FDA-approved drug Enzalutamide. Site-directed mutagenesis demonstrated that the developed inhibitors do interact with the intended target site. Importantly, the AR DBD inhibitors could effectively inhibit the growth of Enzalutamide-resistant cells as well as block the transcriptional activity of constitutively active AR splice variants, such as V7.

Astrocyte dysfunction and inflammation are associated with the pathogenesis of major depressive disorder (MDD). However, the mechanisms underlying these effects remain largely unknown. Here, we found that multiple endocrine neoplasia type 1 (Men1; protein: menin) expression is attenuated in the brain of mice exposed to CUMS (chronic unpredictable mild stress) or lipopolysaccharide. Astrocyte-specific reduction of Men1 (GcKO) led to depressive-like behaviors in mice. We observed enhanced NF-κB activation and IL-1β production with menin deficiency in astrocytes, where depressive-like behaviors in GcKO mice were restored by NF-κB inhibitor or IL-1β receptor antagonist. Importantly, we identified a SNP, rs375804228, in human MEN1, where G503D substitution is associated with a higher risk of MDD onset. G503D substitution abolished menin-p65 interactions, thereby enhancing NF-κB activation and IL-1β production. Our results reveal a distinct astroglial role for menin in regulating neuroinflammation in depression, indicating that menin may be an attractive therapeutic target in MDD.

Dietary supplementation of butyrate can prevent diet-induced obesity through increasing mitochondrial function in mice, yet the up-stream signaling pathway remains elusive. In this study, weaned mice were divided into two groups, fed control (CON) and high-fat diet (HF, 45% energy from fat), respectively, for 8 weeks. HFinduced obese mice, maintained on HF diet, were then divided into two groups; HFB group was gavaged with 80 mg sodium butyrate (SB) per mice every other day for 10 days, while the HF group received vehicle. It was shown that five gavage doses of SB significantly alleviated HF diet-induced obesity and restored plasma glucose, insulin and leptin to control levels. Muscle contents of ADP and AMP were significantly increased, which was associated with enhanced mitochondrial oxidative phosphorylation and up-regulated expression of fatty acid oxidation enzymes and uncoupling proteins, UCP2 and UCP3 in the skeletal muscle. SB significantly enhanced the expression of adiponectin receptors (adipoR1/2) and AMP kinase (AMPK), while diminished the expression of histone deacetylase 1 (HDAC1). Higher H3K9Ac, a gene activation histone mark, was detected on the promoter of Adipor1/2, Ucp2 and Ucp3 genes that were activated in the muscle of SB-treated obese mice. Our results indicate that short-term oral administration of SB can alleviate diet-induced obesity and insulin resistance in mice through activation of adiponectin-mediated pathway and stimulation of mitochondrial function in the skeletal muscle.