Reelin regulates differentiation of neural stem cells by activation of notch signaling through Disabled-1 tyrosine phosphorylation

We have previously reported the cross-talk between Reelin and Notch-1 signaling pathways, which are 2 major pathways that regulate brain development. We found that Reelin activated Notch-1 signaling, leading to the expression of brain lipid binding protein (BLBP) and the formation of radial glial cells in human neural progenitor cells (hNPCs). In the current study, we investigated the molecular mechanisms by which Reelin activates Notch-1. We show that Reelin-stimulated Notch-1 activation is dependent on Reelin signaling. The induction of Disabled-1 (Dab-1) tyrosine phosphorylation, and the subsequent activation of Src family kinases, were found to be essential steps for the activation of Notch-1 signaling by Reelin. Reelin treatment increased the interaction between Dab-1 and Notch-1 intracellular domain (NICD), and enhanced NICD translocation to the nucleus. This study advances our knowledge of the regulation of Notch-1 activation by Reelin signaling in hNPCs, as an approach to understanding cell fate determination, differentiation, and neurogenesis during brain development.     

Guiding cellular activity with polarized light

Actin, cytoskeleton protein forming microfilaments, play a crucial role in cellular motility. Here we show that exposure to very low levels of polarized light guide their orientation in‐vivo within the live cell. Using a simple model to describe the role of actin‐filament orientation in directional cellular motion, we demonstrate that the actin polymerization/depolymerization mechanism develops primarily along this direction and, under certain conditions, can lead to guidance of the cell movement. Our results also show a dose dependent increase in actin activity in direct correspondence to the level of laser irradiance. We found that total expression of Tau protein, which stabilize microtubules, was decreased by the irradiance, indicating that exposure to the light may change the activity of kinase, leading to increased cell activity.

     

Endocrine disrupter bisphenol A increases in situ estrogen production in the mouse urogenital sinus

The balance between androgens and estrogens is very important in the development of the prostate, and even small changes in estrogen levels, including those of estrogen-mimicking chemicals, can lead to serious changes. Bisphenol A (BPA), an endocrine-disrupting chemical, is a well-known, ubiquitous, estrogenic chemical. To investigate the effects of fetal exposure to low-dose BPA on the development of the prostate, we examined alterations of the in situ sex steroid hormonal environment in the mouse urogenital sinus (UGS). In the BPA-treated UGS, estradiol (E(2)) levels and CYP19A1 (cytochrome P450 aromatase) activity were significantly increased compared with those of the untreated and diethylstilbestrol (DES)-treated UGS. The mRNAs of steroidogenic enzymes, Cyp19a1 and Cyp11a1, and the sex-determining gene, Nr5a1, were up-regulated specifically in the BPA-treated group. The up-regulation of mRNAs was observed in the mesenchymal component of the UGS as well as in the cerebellum, heart, kidney, and ovary but not in the testis. The number of aromatase-expressing mesenchymal cells in the BPA-treated UGS was approximately twice that in the untreated and DES-treated UGS. The up-regulation of Esrrg mRNA was observed in organs for which mRNAs of steroidogenic enzymes were also up-regulated. We demonstrate here that fetal exposure to low-dose BPA has the unique action of increasing in situ E(2) levels and CYP19A1 (aromatase) activity in the mouse UGS. Our data suggest that BPA might interact with in situ steroidogenesis by altering tissue components, such as the accumulation of aromatase-expressing mesenchymal cells, in particular organs.     

Heterogenous induction of carcinoma-associated fibroblast-like differentiation in normal human prostatic fibroblasts by co-culturing with prostate cancer cells

In the tumor microenvironment, carcinoma-associated fibroblasts (CAFs) are considered to play a critical role in the promotion of tumorigenesis. However, the mechanisms that generate CAFs are not well elucidated. To understand how CAFs are generated during primary cancer progression, we investigated the biochemical characteristics of normal human prostate stromal cells (PrSC) co-cultured with human prostate cancer (PCa) cells in vitro. In primary cultures of human PCa-derived stromal cells (PCaSC-8 and PCaSC-9), expression of TNC, ACTA2, EGF, FGF7, and IGF1 mRNA was generally higher than PrSC but gene expression patterns were not uniform between PCaSC-8 and PCaSC-9 cells. Transforming growth factor β (TGFβ) and vascular endothelial growth factor (VEGF) protein levels in both PCaSC-8 and PCaSC-9 cells were generally higher than PrSC but levels of both secreted proteins were not same. When PrSCs were co-cultured with androgen-sensitive LNCaP cells or its sublines, androgen-low-sensitive E9 cells and androgen-insensitive AIDL cells, mRNA expression of IGF1 was significantly increased in all combinations. In contrast, expression of COL1A1, TNC, and ACTA2 mRNA was significantly increased only in LNCaP + PrSC and E9 + PrSC co-cultures. Protein production of VEGF was significantly increased only in LNCaP + PrSC and E9 + PrSC co-cultures. Increase of TGFβ protein was observed only in E9 + PrSC co-cultures. These biochemical characteristics of PrSC were partially recapitulated in TGFβ-treated PrSC. We have demonstrated that normal fibroblasts co-cultured with cancer cells become activated and exhibit biochemical characteristics of CAFs in a heterogenous manner. Our results suggest that heterogenous induction of CAF-like differentiation might be strongly dependent on biochemical characteristics of adjacent cancer cells.     

Functional characterization of a new human Ad4BP/SF-1 variation, G146A

Ad4BP/SF-1 plays key roles at all levels of the hypothalamic-pituitary-steroidogenic organ axis and its functional disruption causes endocrine disorders of these organs. However, only three human subjects with Ad4BP/SF-1 mutations have been reported to date, suggesting limited clinical significance as a cause of inborn adrenal or sexual abnormalities. We report the first functional characterization of a new variation found in the hinge region of human Ad4BP/SF-1, G146A. Resulting from a single nucleotide shift (GGG-->GCG), G146A bears slightly diminished transactivation activity evidenced by both adrenal specific cyp11A promoter and ovary specific cyp19 promoter II. The variation does not affect protein expression or stability, exhibiting no dominant negative effect. G146A has a normal interaction pattern with standard co-regulators and subnuclear distribution pattern, and can be considered as a nonsynonymous single nucleotide polymorphism, since it occurs in normals and patients with adrenal diseases. In normal Japanese the allele C frequency is 8%, while in a preliminary population of patients with adrenal diseases it is elevated to 30%; suggesting the G146A variation might be of clinical importance.     

Impact of long-term continuous positive airway pressure on liver fat in male obstructive sleep apnea patients with fatty liver

Sleep and Biological Rhythms - Obstructive sleep apnea (OSA) is an established factor in the pathogenesis and exacerbation of fatty liver disease. However, randomized controlled trials have failed...     

MCP-1-Induced Migration of NT2 Neuroprogenitor Cells Involving APP Signaling

Neuroprogenitor cells are an important resource because of their great potential to replace damaged cells in the brain caused by trauma and disease. Studies have shown that when neuroprogenitor cells are transplanted into the brain they migrate towards damaged areas, suggesting that these areas express factors that recruit migrating cells. Generally, after neuronal injury, there is a neuroinflammatory response that results in increased chemokine production. In this present study, we demonstrate that monocyte chemoattractant protein-1 (MCP-1) significantly induces the migration of NT2 neuroprogenitor cells. Activation of intracellular cyclic adenosine monophosphate or protein kinase C with forskolin and phorbol 12-myristate 13-acetate, respectively, was able to completely abolish the MCP-1-induced migration. Contrarily, neither extracellular signal-regulated kinase nor p38 mitogen-activated protein kinase was required for NT2 cells to respond to MCP-1. Previously, we showed that amyloid precursor protein (APP) activity increases MCP-1 expression in NT2 cells. We now demonstrate that NT2 cells expressing APP can induce migration of other neuroprogenitor cells. Utilizing a MCP-1 neutralizing antibody, we discovered that APP-induced migration was not caused solely by increased MCP-1 production. Interestingly, APP-increased expression of several C–C chemokines: MCP-1, regulated upon activation, normal T-cell expressed, and secreted (RANTES), and macrophage inflammatory protein alpha (MIP-1 alpha). This demonstrates the unique role APP has in regulating chemokine production, which directly affects cell migration. Taken together, these data provides greater detail of the chemotactic factors and intracellular signaling that direct neuroprogenitor cell migration, allowing for better understanding of cell migration during transplantation.