AMPK-dependent and independent effects of AICAR and compound C on T-cell responses PMC
AMPK-dependent and independent effects of AICAR and compound C on T-cell responses PMC
Skeletal muscle demonstrates a great degree of metabolic plasticity, with its characteristics subjected to many studies over several decades. Accumulating evidence suggests that a large number of signaling molecules control the metabolic properties of skeletal muscle. The signaling molecule 5′-AMP-activated protein kinase (AMPK) has been shown to play a pivotal role in skeletal muscle cells [1]. All the animals after an overnight fast were measured for the initial glucose level, after which a 40% glucose solution at a dose of 2 mg/kg was injected into the stomach with a probe and the amount of glucose was measured 30, 60, 90, and 120 min after administration. As noted above, initially, all the animals treated with HFD had elevated glucose levels (7.4 ± ۱.۵ mmol/L in group 3, 7.9 ± ۱.۸ mmol/L in group 4, 8.4 ± ۰.۶ mmol/L in group 5, 7.4 ± ۰.۹ mmol/L in group 6 vs. 5.2 ± ۰.۴ mmol/L in group 1 and 6.2 ± ۰.۹ mmol/L in group 2) (Table 3).
Physiological AMPK activation involves phosphorylation of Thr-172 within the activation loop of the KD in the AMPKα catalytic subunit. Two upstream kinases, LKB118 and CaMKKβ (Ca2+/calmodulin-dependent protein kinase β),۱۹ have been extensively documented to phosphorylate Thr-172 of the AMPKα subunit. Treatments that deplete cellular ATP do not effectively activate AMPK in LKB1-negative tumors because the basal activity of CaMKKβ is too https://earthsongbymanyata.com/how-steroids-can-help-athletes-overcome-fatigue-10/ low to affect the phosphorylation status of AMPKα Thr172, although the increase in AMP due to ATP depletion makes the AMPK α-subunit a better substrate for CaMKKβ.
Western Blot Analysis
Thus, clinical application of AMPK agonists/antagonists will most likely influence T cell survival and function. Although the effects of AICAR and Compound C on T cell activity has been studied [30, 33-37], whether these effects are dependent or independent of AMPK is still unclear. Here, using AMPK-deficient T cells, we investigated the effects of AICAR and Compound C on T cell survival and function. We found that AICAR promoted, but Compound C inhibited, Ca2+ signaling-induced T cell death in an AMPK-dependent manner.
- Our current and previous findings indicate that AICAR prevents transcriptional activation by LPS or ER stress inducers without altering upstream signaling20.
- Thus, pharmacological application of AICAR or Compound C may result in both AMPK-dependent and independent effects in different types of cells.
- However, some hepatotoxic effects were observed when the animals, on a received standard diet (STD), were treated with AICAR starting from the first day of the study.
- Previous studies have shown that the active subunit MUC1-CT is involved in tumorigenesis in lung and other cancers [23,24,25,26,27,28].
- Several animal studies performed in the 1980s demonstrated that AICAr or acadesine infusion improved postischemic recovery in the heart [53,54], and prompted the first international randomized studies in human participants undergoing coronary artery bypass graft surgery (CAGS).
To further confirm these observations, we measured CD69 expression on T cells activated with anti-CD3/CD28 antibodies. Both AICAR and Compound C inhibited CD69 expression on anti-CD3/CD28-activated T cells from WT and KO mice. In addition, other T cell activation markers, including CD25, CD71, were also inhibited by AICAR or Compound C treatment (Figure 3E, 3F). Taken together, these data suggest that T cell activation does not require AMPK expression and both AICAR and Compound C are able to inhibit T cell activation in an AMPK-independent manner. To further visualise the subcellular localisation of MUC1-CT, we performed immunofluorescence staining for MUC1-CT in H441 cells.
Body composition
However, treatment with AICAR significantly restored the antioxidant abilities of the liver, as evidenced by an obvious elevation in hepatic concentrations of SOD and a marked decline in the hepatic levels of MDA (Figure 3F). These data suggest that AICAR supplementation prevents sodium taurocholate-induced PALI in rats by increasing antioxidant activities in the liver. We next determined whether AICAR or Compound C affects T cell function by measurement of cytokine production in activated T cells. In line with our previous data [10], deletion of AMPK in T cells greatly impaired production of IL-2, IFNγ and TNFα in PMA/Ionomycin-activated CD8+ T cells (DMSO control group in Figure 4A, 4B, 4C), implying that AMPK activation contributes to cytokine production in T cells. Of note, similar inhibitory effects were also observed in CD4+ T cells, regardless of AMPK expression (Figure 4D, 4E). We found that AMPK expression was still able to promote cytokine production in both CD4+ and CD8+ T cells (left panel, Figure S5).
Adenosine is a potent vasodilator that plays a key role in reducing ischemia/reperfusion injury, but the applications for systemic adenosine are limited owing to peripheral hemodynamic actions [13]. As shown in Figure 1, AICAr shares structural similarities with adenosine, and therefore, can increase the extracellular concentrations of adenosine by competing for the nucleoside transporter [20]. In addition, AICAR increases intracellular concentrations by inhibiting adenosine deaminase and increasing the production of adenosine rather than inosine from ATP catabolism. Several animal studies performed in the 1980s demonstrated that AICAr or acadesine infusion improved postischemic recovery in the heart [53,54], and prompted the first international randomized studies in human participants undergoing coronary artery bypass graft surgery (CAGS).
Organoids and tumours from patients and transgenic mice were treated with AICAR alone or in combination with JAK and EGFR inhibitors to evaluate treatment effects. Four consecutive cystathionine-β-synthase domains in the AMPKγ subunit provide four potential adenine nucleotide-binding sites. The catalytic AMPKα subunit contains an N-terminal kinase domain (KD) immediately followed by an autoinhibitory domain (AID).
Our findings demonstrated that AICAR activates AMPK, which leads to Nrf2-mediated antioxidant stress and inhibition of NLRP3-related inflammation, and thus improving PALI. This study indicated that AMPK exerted an essential role in the pathological processes of PALI and presented the first evidence that pharmacological activation of AMPK by AICAR ameliorates PALI, suggesting that AICAR may be a promising therapeutic agent for the treatment of PALI. 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR) is an intermediate in the generation of inosine monophosphate and analog of adenosine monophosphate (AMP) that is capable of stimulating AMP-dependent protein kinase (AMPK) activity.
AMPK activity can be regulated by intracellular factors, such as the cellular AMP/ATP ratio, as well as auto-inhibitory features and phosphorylation status of its subunits. Full activation of AMPK requires specific phosphorylation of the α subunit at the conserved threonine residue (Thr172) by upstream kinases including LKB1, CAMKKs and TAK1. Protein phosphatases 2A and 2C also regulate the activation of AMPK by dephosphorylation of Thr172 [1, 5]. It is well-established that activation of AMPK is critical in restoring the intracellular energy balance to sustain cell survival and function under stress via turning off ATP-consuming anabolic pathways and stimulating ATP-producing catabolic processes [2, 4, 6].