Multipotent Stromal Cells from Subcutaneous Adipose Tissue of Normal Weight and Obese Subjects: Modulation of Their Adipogenic Differentiation by Adenosine A1 Receptor Ligands

Adenosine A1 receptor (A1R) activation, stimulating lipogenesis and decreasing insulin resistance, could be useful for metabolic syndrome management in obese subjects. Since full A1R agonists induce harmful side-effects, while partial agonists show a better pharmacological profile, we investigated the influence of two derivatives of the full A1R agonist 2-chloro-N6-cyclopentyladenosine (CCPA), C1 and C2 behaving as A1R partial agonists in animal models, on the adipogenic differentiation of stromal/stem cells (ASCs) from human subcutaneous adipose tissue, which mainly contribute to increase fat mass in obesity. The ASCs from normal-weight subjects showed increased proliferation and A1R expression but reduced adipogenic differentiation compared to obese individual-derived ASCs. Cell exposure to CCPA, C1, C2 or DPCPX, an A1R antagonist, did not affect ASC proliferation, while mainly C2 and DPCPX significantly decreased adipogenic differentiation of both ASC types, reducing the activity of glycerol-3-phosphate dehydrogenase and the expression of PPARγ and FABP-4, all adipogenic markers, and phosphorylation of Akt in the phosphatidylinositol-3-kinase pathway, which plays a key-role in adipogenesis. While requiring confirmation in in vivo models, our results suggest that A1R partial agonists or antagonists, by limiting ASC differentiation into adipocytes and, thereby, fat mass expansion, could favor development/worsening of metabolic syndrome in obese subjects without a dietary control.

In silico identification of A1 agonists and A2a inhibitors in pain based on molecular docking strategies and dynamics simulations

Most recently, the adenosine is considered as one of the most promising targets for treating pain, with few side effects. It exists in the central nervous system, and plays a key role in nociceptive afferent pathway. It is reported that the A1 receptor (A1R) could inhibit Ca2+ channels to reduce the pain like analgesic mechanism of morphine. And, A2a receptor (A2aR) was reported to enhance the accumulation of AMP (cAMP) and released peptides from sensory neurons, resulting in constitutive activation of pain. Much evidence showed that A1R and A2aR could be served as the interesting targets for the treatment of pain. Herein, virtual screening was utilized to identify the small molecule compounds towards A1R and A2aR, and top six molecules were considered as candidates via amber scores. The molecular dynamic (MD) simulations and molecular mechanics/generalized born surface area (MM/GBSA) were employed to further analyze the affinity and binding stability of the six molecules towards A1R and A2aR. Moreover, energy decomposition analysis showed significant residues in A1R and A2aR, including His1383, Phe1276, and Glu1277. It provided basics for discovery of novel agonists and antagonists. Finally, the agonists of A1R (ZINC19943625, ZINC13555217, and ZINC04698406) and inhibitors of A2aR (ZINC19370372, ZINC20176051, and ZINC57263068) were successfully recognized. Taken together, our discovered small molecules may serve as the promising candidate agents for future pain research.

Adenosine A1 Receptor Deficiency Aggravates Extracellular Matrix Accumulation in Diabetic Nephropathy through Disturbance of Peritubular Microenvironment

Background. We previously observed that adenosine A1 receptor (A1AR) had a protective role in proximal tubular megalin loss associated with albuminuria in diabetic nephropathy (DN). In this study, we aimed to explore the role of A1AR in the fibrosis progression of DN. Methods. We collected DN patients’ samples and established a streptozotocin-induced diabetes model in wild-type (WT) and A1AR-deficient (A1AR-/-) mice. The location and expression of CD34, PDGFRβ, and A1AR were detected in kidney tissue samples from DN patients by immunofluorescent and immunohistochemical staining. We also analyzed the expression of TGFβ, collagen (I, III, and IV), α-SMA, and PDGFRβ using immunohistochemistry in WT and A1AR-/- mice. CD34 and podoplanin expression were analyzed by Western blotting and immunohistochemical staining in mice, respectively. Human renal proximal tubular epithelial cells (HK2) were cultured in medium containing high glucose and A1AR agonist as well as antagonist. Results. In DN patients, the expression of PDGFRβ was higher with the loss of CD34. The location of PDGFRβ and TGFβ was near to each other. The A1AR, which was colocalized with CD34 partly, was also upregulated in DN patients. In WT-DN mice, obvious albuminuria and renal pathological leisure were observed. In A1AR-/- DN mice, more severe renal tubular interstitial fibrosis and more extracellular matrix deposition were observed, with lower CD34 expression and pronounced increase of PDGFRβ. In HK2 cells, high glucose stimulated the epithelial-mesenchymal transition (EMT) process, which was inhibited by A1AR agonist. Conclusion. A1AR played a critical role in protecting the tubulointerstitial fibrosis process in DN by regulation of the peritubular microenvironment.

Clock genes Period1 and Period2 in the hippocampal CA1 mediate depression-like behaviors and rapid antidepressant response

Accumulated reports have indicated that circadian rhythm is closely related to the pathogenesis of major depressive disorder (MDD). Recently, adenosine has been identified to modulate circadian clock via adenosine A1 and A2A receptor signaling pathways. Cyclic AMP-response element binding protein (CREB) is a convergent point that plays a critical role in the pathogenesis of depression and is a downstream molecule of adenosine A1 receptor signaling pathway as an endpoint that can regulate the expression of circadian genes Period1 (Per1) and Period2 (Per2). However, whether Per mediates the development of MDD via CREB has not been elucidated. We used chronic unpredictable stress (CUS) to induce depression-like behaviors and found that it could induce decrease in p-CREB and PER1 levels in the hippocampal CA1 region in rats. Both depression-like behaviors and the decreased protein levels could be rapidly rescued by the administration of adenosine A1 receptor agonist 2-Choro-N6-cyclopentyladenosine (CCPA). Furthermore, knockdown of Per1 in hippocampal CA1 region could also induce depression-like behaviors, which could also be rescued by CCPA. Interestingly, Per2 knockdown in hippocampal CA1 region resulted in potential antidepressant-like effect. In addition, knockout of CRE sequence in the promoter regions of either Per1 or Per2 led to depression-like behaviors, which could not be rescued by CCPA. These results indicated that clock genes Per1 and Per2 play critical roles in the pathophysiology of depression and CRE sequences in the promoter regions of Per1 and Per2 may be a critical antidepressant target.

Electroacupuncture Pretreatment Prevents Cognitive Impairment Induced by Cerebral Ischemia–Reperfusion via Adenosine A1 Receptors in Rats

A previous study has demonstrated that pretreatment with electroacupuncture (EA) induces rapid tolerance to focal cerebral ischemia. In the present study, we investigated whether adenosine receptor 1 (A1 R) is involved in EA pretreatment-induced cognitive impairment after focal cerebral ischemia in rats. Two hours after EA pretreatment, focal cerebral ischemia was induced by middle cerebral artery occlusion for 120 min in male Sprague-Dawley rats. The neurobehavioral score, cognitive function [as determined by the Morris water maze (MWM) test], neuronal number, and the Bax/Bcl-2 ratio was evaluated at 24 h after reperfusion in the presence or absence of CCPA (a selective A1 receptor agonist), DPCPX (a selective A1 receptor antagonist) into left lateral ventricle, or A1 short interfering RNA into the hippocampus area. The expression of the A1 receptor in the hippocampus was also investigated. The result showed that EA pretreatment upregulated the neuronal expression of the A1 receptor in the rat hippocampus at 90 min. And EA pretreatment reversed cognitive impairment, improved neurological outcome, and inhibited apoptosis at 24 h after reperfusion. Pretreatment with CCPA could imitate the beneficial effects of EA pretreatment. But the EA pretreatment effects were abolished by DPCPX. Furthermore, A1 receptor protein was reduced by A1 short interfering RNA which attenuated EA pretreatment-induced cognitive impairment.