ß2-Adrenoreceptor-Mediated Proliferation Inhibition of Embryonic Pluripotent Stem Cells.

Adrenoreceptors (ARs) are widely expressed and play essential roles throughout the body. Different subtype adrenoceptors elicit distinct effects on cell proliferation, but knowledge remains scarce about the subtype-specific effects of ß2-ARs on the proliferation of embryonic pluripotent stem (PS) cells that represent different characteristics of proliferation and cell cycle regulation with the somatic cells. Herein, we identified a ß2-AR/AC/cAMP/PKA signaling pathway in embryonic PS cells and found that the pathway stimulation inhibited proliferation and cell cycle progression involving modulating the stem cell growth and cycle regulatory machinery. Embryonic stem (ES) cells and embryonal carcinoma stem (ECS) cells expressed functional ß-ARs coupled to AC/cAMP/PKA signaling. Agonistic activation of ß-ARs led to embryonic PS cell cycle arrest and proliferation inhibition. Pharmacological and genetic analyzes using receptor subtype blocking and RNA interference approaches revealed that this effect selectively depended on ß2-AR signaling involving the regulation of AKT, ERK, Rb, and Cyclin E molecules. Better understanding of the effects of ß2-ARs on embryonic PS cell proliferation and cycle progression may provide new insights into stem cell biology and afford the opportunity for exploiting more selective ligands targeting the receptor subtype for the modulation of stem cells.

Synthesis and evaluation of benzylisoquinoline derivatives for their inhibition on pancreatic lipase and preadipocyte proliferation.

The present study was designed to synthesize and evaluate a series of benzylisoquinoline derivatives. These compounds were synthesized by Bischler-Napieralski cyclization to yield 1-benzyl-3,4-dihydroisoquinolines, and the products were obtained by reductions. All these compounds were identified by MS, (1)H NMR and (13)C NMR. The inhibitory activities on pancreatic lipase and preadipocyte proliferation for the synthesized compounds and alkaloids from Nulembo nucifera were assessed in vitro. Most of the compounds showed inhibitory activities on both pancreatic lipase and preadipocyte proliferation. Particularly, compounds 7p-7u and 9d-9f exhibited significant inhibitory activity on pancreatic lipase while compounds 7c, 7d, 7f, 7g, 7i, and 7j potently inhibited the proliferation of 3T3-L1 preadipocytes. Our results provided a basis for future evaluation and development of these compounds as leads for therapeutics for human diseases.

Simultaneous determination of the repertoire of classical neurotransmitters released from embryonal carcinoma stem cells using online microdialysis coupled with hydrophilic interaction chromatography-tandem mass spectrometry.

Dynamic, continuous, and simultaneous multi-analysis of transmitters is important for the delineation of the complex interactions between the neuronal and intercellular communications. But the analysis of the whole repertoire of classical transmitters of diverse structure is challenging due to their different physico-chemical properties and to their high polarity feature which leads to poor retention in traditional reversed-phase columns during LC-MS analysis. Here, an online microdialysis coupled with hydrophilic interaction chromatography-tandem mass spectrometry (online MD-HILIC-MS/MS) detection method was developed for the simultaneous measurement of the repertoire of classical transmitters (acetylcholine, serotonin, dopamine, norepinephrine, glutamate, GABA, and glycine). Stable isotope labeled internal standards and authentic matrix have been applied to guarantee reliable results. The method was successfully employed to reveal the characteristics of transmitter release from embryonal carcinoma stem cells. The method features simple procedure (no sample preparation), high recovery (≥ 73%), high accuracy (89.36%≤RE≤116.89%), good reproducibility (2.18%≤ RSD ≤14.56%), and sensitive limits of detection (2 pg for acetylcholine, serotonin, and glutamate, 10 pg for dopamine, norepinephrine, GABA, and glycine). It can be flexibly applied to determine the contents of the classical transmitters in other biological matrix samples with minor changes.

Non-neuronal release of gamma-aminobutyric Acid by embryonic pluripotent stem cells.

γ-Aminobutyric acid (GABA), the principle inhibitory transmitter in the mature central nervous system, is also involved in activities outside the nervous system. Recent studies have shown that functional GABA receptors are expressed in embryonic stem (ES) cells and these receptors control ES cell proliferation. However, it is not clear whether ES cells have their own GABAergic transmission output machinery that can fulfill GABA release or whether the cells merely process the GABA receptors by receiving and responding to the diffused GABA released elsewhere. To get further insight into this unresolved problem, we detected the repertoire of components for GABA synthesis, storage, reaction, and termination in ES and embryonal carcinoma stem cells by biological assays, and then directly quantified released GABA in the intercellular milieu from these pluripotent stem (PS) cells by an analytical chemical assay based on high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). We found that embryonic PS cells processed a GABAergic circuit machinery and spontaneously released GABA, which suggests the potential that embryonic PS cells could autonomously establish a GABA niche via release of the transmitter.