PPARγ Loss Leads to Reduced Fertility

The peroxisome proliferation-activated receptor gamma (PPARγ) is expressed in many cell types including mammary epithelium, ovary, macrophages, and B- and T-cells. PPARγ has an anti-proliferative effect in pre-adipocytes and mammary epithelial cells, and treatment with its ligands reduced the progression of carcinogen-induced mammary tumors in mice. Because PPARγ-null mice die in utero it has not been possible to study its role in development and tumorigenesis in vivo. To investigate whether PPARγ is required for the establishment and physiology of different cell types, a cell-specific deletion of the gene was carried out in mice using the Cre-loxP recombination system. We deleted the PPARγ gene in mammary epithelium using WAP-Cre transgenic mice and in epithelial cells, B- and T-cells, and ovary cells using MMTV-Cre mice. The presence of PPARγ was not required for functional development of the mammary gland during pregnancy and for the establishment of B- and T-cells. In addition, no increase in mammary tumors was observed. However, loss of the PPARγ gene in oocytes and granulosa cells resulted in impaired fertility. These mice have normal populations of follicles, they ovulate and develop corpora lutea. Although progesterone levels are decreased and implantation rates are reduced, the exact cause of the impaired fertility remains to be determined

Monocytes Do Not Transdifferentiate into Proper Osteoblasts

Recent publications suggested that monocytes might be an attractive cell type to transdifferentiate into various cellular phenotypes. Aim was, therefore, to evaluate the potential of blood monocytes to transdifferentiate into osteoblasts. Monocytes isolated from peripheral blood were subjected to two previously published treatments to obtain unique, multipotent cell fractions, named programmable cells of monocytic origin (PCMOs) and monocyte-derived mesenchymal progenitor cells (MOMPs). Subsequently, MOMPs and PCMOs were treated with osteogenic differentiation medium (including either vitamin D or dexamethasone) for 14 days. Regarding a variety of surface markers, no differences between MOMPs, PCMOs, and primary monocytes could be detected. The treatment with osteogenic medium neither resulted in loss of hematopoietic markers nor in adoption of mesenchymal phenotype in all cell types. No significant effect was observed regarding the expression of osteogenic transcription factors, bone-related genes, or production of mineralized matrix. Osteogenic medium resulted in activation of monocytes and appearance of osteoclasts. In conclusion, none of the investigated monocyte cell types showed any transdifferentiation characteristics under the tested circumstances. Based on our data, we rather see an activation and maturation of monocytes towards macrophages and osteoclasts

Quercetin Protects Primary Human Osteoblasts Exposed to Cigarette Smoke through Activation of the Antioxidative Enzymes HO-1 and SOD-1

Smokers frequently suffer from impaired fracture healing often due to poor bone quality and stability. Cigarette smoking harms bone cells and their homeostasis by increased formation of reactive oxygen species (ROS). The aim of this study was to investigate whether Quercetin, a naturally occurring antioxidant, can protect osteoblasts from the toxic effects of smoking. Human osteoblasts exposed to cigarette smoke medium (CSM) rapidly produced ROS and their viability decreased concentration- and time-dependently. Co-, pre- and postincubation with Quercetin dose-dependently improved their viability. Quercetin increased the expression of the anti-oxidative enzymes heme-oxygenase- (HO-) 1 and superoxide-dismutase- (SOD-) 1. Inhibiting HO-1 activity abolished the protective effect of Quercetin. Our results demonstrate that CSM damages human osteoblasts by accumulation of ROS. Quercetin can diminish this damage by scavenging the radicals and by upregulating the expression of HO-1 and SOD-1. Thus, a dietary supplementation with Quercetin could improve bone matter, stability and even fracture healing in smokers

A family of serine proteases expressed exclusively in myelo-monocytic cells specifically processes the nuclear factor-�B subunit p65 in vitro and may impair human immunodeficiency virus replication in these cells

Two groups of U937 promonocytic cells were obtained by limiting dilution cloning which differed strikingly in their ability to support human immunodeficiency virus 1 (HIV-1) replication. "Plus" clones replicated the virus efficiently, whereas "minus " clones did not. We examined these clones for differences in nuclear factor (NF)-xB activity which might account for the observed phenomenon. Stimulation ofphs clones liberated the classical p50-p65 complex from cytoplasmic pools, whereas minus clones produced an apparently novel, faster-migrating complex, as judged by dectrophoretic mobility shift assays. It is surprising that the faster-migrating complex was composed also of p50 and p65. However, the p65 subunit was COOH-terminally truncated, as shown by immunoprecipitation. The truncation resulted from limited proteolysis of p65 during cellular extraction which released particular lysosomal serine proteases, such as dastase, cathepsin G, and proteinase 3. These specific proteases are coordinately expressed and were present exclusively in the minus U937 clones, but not in the plus clones, as demonstrated in the case of cathepsin G. In addition, these proteases were detected in certain subclones of THP-1 and HL-60 cells and in primary monocytes, in each case correlating with the truncated form of p65. We demonstrate in vitro cleavage of p65 by purified elastase and cathepsin G. It is possible that particular serin

A family of serine proteases expressed exclusively in myelo-monocytic cells specifically processes the nuclear factor-rd3 subunit p65 in vitro and may impair human immunodeficiency virus replication in these cells.J. Exp. Meal

Two groups of U937 promonocytic cells were obtained by limiting dilution cloning which differed strikingly in their ability to support human immunodeficiency virus 1 (HIV-1) replication. "Plus" clones replicated the virus efficiently, whereas "minus " clones did not. We examined these clones for differences in nuclear factor (NF)-xB activity which might account for the observed phenomenon. Stimulation ofphs clones liberated the classical p50-p65 complex from cytoplasmic pools, whereas minus clones produced an apparently novel, faster-migrating complex, as judged by dectrophoretic mobility shift assays. It is surprising that the faster-migrating complex was composed also of p50 and p65. However, the p65 subunit was COOH-terminally truncated, as shown by immunoprecipitation. The truncation resulted from limited proteolysis of p65 during cellular extraction which released particular lysosomal serine proteases, such as dastase, cathepsin G, and proteinase 3. These specific proteases are coordinately expressed and were present exclusively in the minus U937 clones, but not in the plus clones, as demonstrated in the case of cathepsin G. In addition, these proteases were detected in certain subclones of THP-1 and HL-60 cells and in primary monocytes, in each case correlating with the truncated form of p65. We demonstrate in vitro cleavage of p65 by purified elastase and cathepsin G. It is possible that particular serin