The current study was performed to investigate the effect of adenosine monophosphate (AMP) - activated protein kinase (AMPK) activation on the extracellular matrix (ECM) remodeling of pulmonary arteries in pulmonary arterial hypertension (PAH) and to address its potential mechanisms.

Quantum dots (QDs) are engineered nanoparticles that possess special optical and electronic properties and have shown great promise for future biomedical applications. In this work, adenosine 5'-monophosphate (AMP), a small biocompatible molecular, was conjugated to organic QDs to produce hydrophilic AMP-QDs. Using macrophage J774A.1 as the cell model, AMP-QDs exhibited both prior imaging property and low toxicity, and more importantly, triggered limited innate immune responses in macrophage, indicating low immunotoxicity in vitro. Using BALB/c mice as the animal model, AMP-QDs were found to be detained in immune organs but did not evoke robust inflammation responses or obvious histopathological abnormalities, which reveals low immunotoxicity in vivo. This work suggests that AMP is an excellent surface ligand with low immunotoxicity, and potentially used in surface modification for more extensive nanoparticles.

The aims of the present study were to examine signaling mechanisms underlying transforming growth factor β1 (TGF-β1)-induced airway smooth muscle cells (ASMCs) proliferation and to determine the effect of adenosine monophosphate-activated protein kinase (AMPK) activation on TGF-β1-induced ASMCs proliferation and its potential mechanisms. TGF-β1 reduced microRNA-206 (miR-206) level by activating Smad2/3, and this in turn up-regulated histone deacetylase 4 (HDAC4) and consequently increased cyclin D1 protein leading to ASMCs proliferation. Prior incubation of ASMCs with metformin induced AMPK activation and blocked TGF-β1-induced cell proliferation. Activation of AMPK slightly attenuated TGF-β1-induced miR-206 suppression, but dramatically suppressed TGF-β1-caused HDAC4 up-expression and significantly increased HDAC4 phosphorylation finally leading to reduction of up-regulated cyclin D1 protein expression. Our study suggests that activation of AMPK modulates miR-206/HDAC4/cyclin D1 signaling pathway, particularly targeting on HDAC4, to suppress ASMCs proliferation and therefore has a potential value in the prevention and treatment of asthma by alleviating airway remodeling.

The aims of the present study were to investigate the signaling mechanisms for sphingosine-1-phosphate (S1P)-induced airway smooth muscle cells (ASMCs) proliferation and to explore the effect of activation of adenosine monophosphate-activated protein kinase (AMPK) on S1P-induced ASMCs proliferation and its underlying mechanisms. S1P phosphorylated signal transducer and activator of transcription 3 (STAT3) through binding to S1PR2/3, and this further sequentially up-regulated polo-like kinase 1 (PLK1) and inhibitor of differentiation 2 (ID2) protein expression. Pretreatment of cells with S1PR2 antagonist JTE-013, S1PR3 antagonist CAY-10444, knockdown of STAT3, PLK1 and ID2 attenuated S1P-triggered ASMCs proliferation. In addition, activation of AMPK by metformin inhibited S1P-induced ASMCs proliferation by suppressing STAT3 phosphorylation and therefore suppression of PLK1 and ID2 protein expression. Our study suggests that S1P promotes ASMCs proliferation by stimulating S1PR2/3/STAT3/PLK1/ID2 axis, and activation of AMPK suppresses ASMCs proliferation by targeting on STAT3 signaling pathway. Activation of AMPK might benefit asthma by inhibiting airway remodeling.

It has been shown that activation of adenosine monophosphate-activated protein kinase (AMPK) suppresses proliferation of a variety of tumor cells as well as nonmalignant cells. In this study, we used post-transcriptional gene silencing with small interfering RNA (siRNA) to specifically examine the effect of AMPK on pulmonary arterial smooth muscle cells (PASMCs) proliferation and to further elucidate its underlying molecular mechanisms. Our results showed that knockdown of AMPKα2 promoted primary cultured PASMCs proliferation; this was accompanied with the elevation of phosphorylation of mammalian target of rapamycin (mTOR) and S-phase kinase-associated protein 2 (Skp2) protein level and reduction of p27(Kip1). Importantly, prior silencing of mTOR with siRNA abolished AMPKα2 knockdown-induced Skp2 upregulation, p27(Kip1) reduction as well as PASMCs proliferation. Furthermore, pre-depletion of Skp2 by siRNA also eliminated p27(Kip1) downregulation and PASMCs proliferation caused by AMPKα2 knockdown. Taken together, our study indicates that AMPKα2 isoform plays an important role in regulation of PASMCs proliferation by modulating mTOR/Skp2/p27(Kip1) axis, and suggests that activation of AMPKα2 might have potential value in the prevention and treatment of pulmonary arterial hypertension.

Electroacupuncture (EA) is widely used in clinical practice to relieve migraine pain. 5-HT7 receptor (5-HT7R) has been reported to play an excitatory role in neuronal systems and regulate hyperalgesic pain and neurogenic inflammation. 5-HT7R could influence phosphorylation of protein kinase A (PKA)- or extracellular signal-regulated kinase1 / 2 (ERK1 / 2)-mediated signaling pathways, which mediate sensitization of nociceptive neurons via interacting with cyclic adenosine monophosphate (cAMP). In this study, we evaluated the role of 5-HT7R in the antihyperalgesic effects of EA and the underlying mechanism through regulation of PKA and ERK1 / 2 in trigeminal ganglion (TG) and trigeminal nucleus caudalis (TNC). Hyperalgesia was induced in rats with dural injection of inflammatory soup (IS) to cause meningeal neurogenic inflammatory pain. Electroacupuncture was applied for 15 min every other day before IS injection. Von Frey filaments, tail-flick, hot-plate, and cold-plated tests were used to evaluate the mechanical and thermal hyperalgesia. Neuronal hyperexcitability in TNC was studied by an electrophysiological technique. The 5-HT7R antagonist (SB269970) or 5-HT7R agonist (AS19) was administered intrathecally before each IS application at 2-day intervals during the 7-day injection protocol. The changes in 5-HT7R and 5-HT7R-associated signaling pathway were examined by real-time polymerase chain reaction (RT-PCR), Western blot, immunofluorescence, and enzyme-linked immunosorbent assay (ELISA) analyses. When compared with IS group, mechanical and thermal pain thresholds of the IS + EA group were significantly increased. Furthermore, EA prevented the enhancement of both spontaneous activity and evoked responses of second-order trigeminovascular neurons in TNC. Remarkable decreases in 5-HT7R mRNA expression and protein levels were detected in the IS + EA group. More importantly, 5-HT7R agonist AS19 impaired the antihyperalgesic effects of EA on p-PKA and p-ERK1 / 2. Injecting 5-HT7R antagonist SB-269970 into the intrathecal space of IS rats mimicked the effects of EA antihyperalgesia and inhibited p-PKA and p-ERK1 / 2. Our findings indicate that 5-HT7R mediates the antihyperalgesic effects of EA on IS-induced migraine pain by regulating PKA and ERK1 / 2 in TG and TNC.