Ecto-5'-nucleotidase (CD73) inhibits dorsal root ganglion neuronal apoptosis by promoting the Ado/cAMP/PKA/CREB pathway

Mechanistic Implications of GSK and CREB Crosstalk in Ischemia Injury

Ischemia-reperfusion (IR) injury is a damage to an organ when the blood supply is less than the demand required for normal functioning, leading to exacerbation of cellular dysfunction and death. IR injury occurs in different organs like the kidney, liver, heart, brain, etc., and may not only involve the ischemic organ but also cause systemic damage to distant organs. Oxygen-glucose deprivation in cells causes oxidative stress, calcium overloading, inflammation, and apoptosis. CREB is an essential integrator of the body's various physiological systems, and it is widely accepted that dysfunction of CREB signaling is involved in many diseases, including ischemia-reperfusion injury. The activation of CREB can provide life to a cell and increase the cell's survival after ischemia. Hence, GSK/CREB signaling pathway can provide significant protection to cells of different organs after ischemia and emerges as a futuristic strategy for managing ischemia-reperfusion injury. Different signaling pathways such as MAPK/ERK, TLR4/MyD88, RISK, Nrf2, and NF-κB, get altered during IR injury by the modulation of GSK-3 and CREB (cyclic AMP response element (CRE)-binding protein). GSK-3 (protein kinase B) and CREB are the downstream targets for fulfilling the roles of various signaling pathways. Calcium overloading during ischemia increases the expression of calcium-calmodulin-dependent protein kinase (CaMK), which subsequently activates CREB-mediated transcription, thus promoting the survival of cells. Furthermore, this review highlights the crosstalk between GSK-3 and CREB, promoting survival and rendering the cells resistant to subsequent severe ischemia.

E prostanoid receptor-3 promotes oxidized low-density lipoprotein-induced human aortic smooth muscle cells inflammation

AIM

The progression of atherosclerosis can lead to the occurrence of multiple cardiovascular diseases (coronary heart disease, etc.). E prostanoid receptor-3 (EP3) is known to participate in the progression of atherosclerosis. This study aimed to investigate the mechanism by which EP3 modulates the development of atherosclerosis.

METHODS AND RESULTS

ApoE^-/- mice were used to construct in vivo model of atherosclerosis. Human aortic smooth muscle cells (HASMCs) were stimulated with oxidized low-density lipoprotein (ox-LDL) to construct in vitro model of atherosclerosis. mRNA expressions were assessed by qRT-PCR, and western blot was applied to assess the protein levels. CCK-8 assay was applied to assess the cell viability. The inflammatory cytokines levels were assessed by enzyme-linked immunosorbent assay, and flow cytometry was applied to assess cell apoptosis. In vivo experiment was constructed to investigate the impact of EP3 in atherosclerosis development. L-798106 (EP3 inhibitor) significantly inhibited the levels of pro-inflammatory cytokines in atherosclerosis in vivo. EP3 inhibitor (L-798106) significantly reversed ox-LDL-caused HASMCs injury via inhibiting the apoptosis and inflammatory responses (P < 0.05). The levels of interleukin-17 (IL-17) and intercellular adhesion molecule-1 (ICAM-1) in HASMCs were elevated by ox-LDL, whereas L-798106 or knockdown of cyclic AMP (cAMP) response element-binding protein (CREB) notably restored this phenomenon (P < 0.05). EP3 overexpression further aggravated ox-LDL-induced inflammation in HASMCs, and EP3 up-regulated the levels of IL-17 and ICAM-1 in ox-LDL-treated HASMCs (P < 0.05). EP3 up-regulation promoted the inflammatory responses in ox-LDL-treated HASMCs through mediation of cAMP/protein kinase A (PKA)/CREB/IL-17/ICAM-1 axis (P < 0.05).

CONCLUSIONS

EP3 inhibitor alleviates ox-LDL-induced HASMC inflammation via mediation of cAMP/PKA/CREB/IL-17/ICAM-1 axis. Our study might shed new lights on discovering novel strategies against atherosclerosis.

Implications of microglial heterogeneity in spinal cord injury progression and therapy

Microglia are widely distributed in the central nervous system (CNS), where they aid in the maintenance of neuronal function and perform key auxiliary roles in phagocytosis, neural repair, immunological control, and nutrition delivery. Microglia in the undamaged spinal cord is in a stable state and serve as immune monitors. In the event of spinal cord injury (SCI), severe changes in the microenvironment and glial scar formation lead to axonal regeneration failure. Microglia participates in a series of pathophysiological processes and behave both positive and negative consequences during this period. A deep understanding of the characteristics and functions of microglia can better identify therapeutic targets for SCI. Technological innovations such as single-cell RNA sequencing (Sc-RNAseq) have led to new advances in the study of microglia heterogeneity throughout the lifespan. Here,We review the updated studies searching for heterogeneity of microglia from the developmental and pathological state, survey the activity and function of microglia in SCI and explore the recent therapeutic strategies targeting microglia in the CNS injury.

Ginsenoside Rb1 improves energy metabolism after spinal cord injury

Mitochondrial damage caused by oxidative stress and energy deficiency induced by focal ischemia and hypoxia are important factors that aggravate diseases. Studies have shown that ginsenoside Rb1 has neurotrophic and neuroprotective effects. However, whether it influences energy metabolism after spinal cord injury remains unclear. In this study, we treated mouse and cell models of spinal cord injury with ginsenoside Rb1. We found that ginsenoside Rb1 remarkably inhibited neuronal oxidative stress, protected mitochondria, promoted neuronal metabolic reprogramming, increased glycolytic activity and ATP production, and promoted the survival of motor neurons in the anterior horn and the recovery of motor function in the hind limb. Because sirtuin 3 regulates glycolysis and oxidative stress, mouse and cell models of spinal cord injury were treated with the sirtuin 3 inhibitor 3-TYP. When Sirt3 expression was suppressed, we found that the therapeutic effects of ginsenoside Rb1 on spinal cord injury were remarkably inhibited. Therefore, ginsenoside Rb1 is considered a potential drug for the treatment of spinal cord injury, and its therapeutic effects are closely related to sirtuin 3.

Integrating network pharmacology and experimental verification to explore the mechanism of puerarin against oliguria in acute alcoholism

Purpose: This study was designed to evaluate the pharmacological mechanisms of puerarin against oliguria in acute alcoholism via network pharmacology analysis combined with experimental verification.

Methods: First, this study established an acute alcoholism rat model, compared the changes in urine volume in each group, and observed the therapeutic effect of puerarin by H&amp;E staining, biochemical, RT-qPCR, and immunohistochemical analyses. Second, puerarin-related targets were searched in TCMS, PubChem, CNKI, Wanfang, PubMed, and GeenMedical Academic databases. Also, potential disease targets were obtained from the GeneCards, MalaCards, and NCBI-gene databases and genes with puerarin target gene intersections were screened out. The interaction network for co-predicted targets was obtained using the STRING database, and the core targets were imported into Cytoscape for visualization using DAVID Bioinformatics Resources 6.8. The essential genes were subjected to the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) pathway enrichment analyses to predict related biological processes and significant signaling pathways. Finally, molecular docking was used to examine the interaction of puerarin with key targets, and the core targets were validated further by RT-qPCR and Western blotting.

Results: Compared to the model group, the urine volume of the rats was significantly increased after puerarin treatment, and the levels of anti-diuretic hormone (ADH) and aquaporin 2 (AQP2) expression were decreased. Searching the intersection of puerarin and acute alcoholism targets yielded 214 potential targets, 837 biological processes, and 185 signaling pathways involved. The molecular docking results indicated a good affinity between puerarin and key targets (cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), cAMP-response element-binding protein (CREB), and c-Fos). RT-qPCR and Western blotting further verified that puerarin could down-regulate the expression of cAMP/PKA/CREB/c-Fos.

Conclusion: This study identified the potential targets of puerarin against oliguria in rats with acute alcoholism using network pharmacology and animal experiments. The mechanism may be closely related to the cAMP signaling pathway.

Diverse actions of sirtuin-1 on ovulatory genes and cell death pathways in human granulosa cells

BACKGROUND

Human granulosa-lutein cells (hGLCs) amply express sirtuin-1 (SIRT1), a NAD + -dependent deacetylase that is associated with various cellular functions. SIRT1 was shown to elevate cAMP on its own and additively with human chorionic gonadotropin (hCG), it is therefore interesting to examine if SIRT1 affects other essential hGLC functions.

METHODS

Primary hGLCs, obtained from the follicular aspirates of women undergoing IVF and SV40-transfected, immortalized hGLCs (SVOG cells), were used. Primary cells were treated with SIRT1 specific activator SRT2104, as well as hCG or their combination. Additionally, siRNA-targeting SIRT1 construct was used to silence endogenous SIRT1 in SVOG cells. PTGS2, EREG, VEGFA and FGF2 expression was determined using quantitative polymerase chain reaction (qPCR). Apoptotic and necroptotic proteins were determined by specific antibodies in western blotting. Cell viability/apoptosis was determined by the XTT and flow cytometry analyses. Data were analyzed using student t-test or Mann-Whitney U test or one-way ANOVA followed by Tukey HSD post hoc test.

RESULTS

In primary and immortalized hGLCs, SRT2104 significantly upregulated key ovulatory and angiogenic genes: PTGS2, EREG, FGF2 and VEGFA, these effects tended to be further augmented in the presence of hCG. Additionally, SRT2104 dose and time-dependently decreased viable cell numbers. Flow cytometry of Annexin V stained cells confirmed that SIRT1 reduced live cell numbers and increased late apoptotic and necrotic cells. Moreover, we found that SIRT1 markedly reduced anti-apoptotic BCL-XL and MCL1 protein levels and increased cleaved forms of pro-apoptotic proteins caspase-3 and PARP. SIRT1 also significantly induced necroptotic proteins RIPK1 and MLKL. RIPK1 inhibitor, necrostatin-1 mitigated SIRT1 actions on RIPK1 and MLKL but also on cleaved caspase-3 and PARP and in accordance on live and apoptotic cells, implying a role for RIPK1 in SIRT1-induced cell death. SIRT1 silencing produced inverse effects on sorted cell populations, anti-apoptotic, pro-apoptotic and necroptotic proteins, corroborating SIRT1 activation.

CONCLUSIONS

These findings reveal that in hGLCs, SIRT1 enhances the expression of ovulatory and angiogenic genes while eventually advancing cell death pathways. Interestingly, these seemingly contradictory events may have occurred in a cAMP-dependent manner.

CD39/CD73 Dysregulation of Adenosine Metabolism Increases Decidual Natural Killer Cell Cytotoxicity: Implications in Unexplained Recurrent Spontaneous Abortion

Unexplained recurrent spontaneous abortion (URSA) is believed to be associated with impaired immunosuppression at the maternal-fetal interface, but the detailed molecular mechanism remains unclear. The ATP-adenosine metabolic pathway regulated by CD39/CD73 has recently been recognized to be important in immunosuppression. This study aimed to investigate the regulation of decidual natural killer (dNK) cells and fetal extravillous trophoblast (EVT) cells by CD39 and CD73 in URSA, as well as the possible regulatory mechanism of CD39/CD73 via the TGF-β-mTOR-HIF-1α pathway using clinical samples and cell models. Fewer CD39⁺ and CD73⁺ cells were found in the URSA decidual and villous tissue, respectively. Inhibition of CD39 on dNK cells transformed the cells to an activated state with increased toxicity and decreased apoptosis, and changed their cytokine secretion, leading to impaired invasion and proliferation of the co-cultured HTR8/SVneo cells. Similarly, inhibition of CD73 on HTR8/SVneo cells decreased the adenosine concentration in the cell culture media, increased the proportion of CD107a⁺ dNK cells, and decreased the invasion and proliferation capabilities of the HTR8/SVneo cells. In addition, transforming growth factor-β (TGF-β) triggered phosphorylation of mammalian target of rapamycin (mTOR) and Smad2/Smad3, which subsequently activated hypoxia-inducible factor-1α (HIF-1α) to induce the CD73 expression on the HTR8/SVneo cells. In summary, reduced numbers of CD39⁺ and CD73⁺ cells at the maternal-fetal interface, which may be due to downregulated TGF-β-mTOR-HIF-1α pathway, results in reduced ATP-adenosine metabolism and increased dNK cytotoxicity, and potentially contributes to URSA occurrences.