It has been suggested that MAPK

It has been suggested that MAPK (Huang et al., 2013, Uddman et al., 2003, Xu et al., 2008) signaling pathway is involved in the transcriptional upregulation of ETB receptor. The present study demonstrated that treatment with CsA increased phosphorylation of ERK1/2 and p38. Inhibition of ERK1/2 and p38 with specific inhibitors attenuated MAPK activation (Fig. 2C and D), increased mRNA (Fig. 3) and protein expression (Fig. 2B) of ETB receptor, and ETB receptor-mediated vasoconstriction in mesenteric MK-4827 Racemate (Fig. 4C–F), indicating that ERK1/2 and p38 MAPK contributed to upregulation of ETB receptor induced by CsA. In addition, N-terminal protein kinase (JNK) inhibitor SP600125 (Bennett et al., 2001) did not change the effects of CsA on S6c response (data not shown). Inflammatory NF-κB signaling pathway is also involved in the transcriptional upregulation of ETB receptor (Huang et al., 2013, Xu et al., 2008, Zheng et al., 2010). Moreover, it has been reported that activation of NF-κB was depended on both ERK1/2 and p38 MAPK signaling pathways (Chen et al., 2004, Kim et al., 2008). In this study, we assumed the possible roles of NF-κB, as the downstream signal of MAPK, in CsA-induced ETB receptor upregulation in VSMC. The data showed that CsA treatment increased IκB degradation (Fig. 2A and E), translocation of NF-κB p65 (Fig. 2A and F), and p65 DNA binding activity (Fig. 2G). Furthermore, inhibition of NF-κB with Bay repressed CsA-induced upregulation of ETB receptor in VSMC at mRNA (Fig. 3), protein (Fig. 2B), and functional levels (Fig. 4H). The data clearly demonstrated that NF-κB signaling pathway was involved in the effects of CsA on ETB receptor in VSMC. In addition, NF-κB activation was suppressed by U0126 and SB203580 (Fig. 2E–F), suggesting that ERK1/2 and p38 MAPK were upstream signaling to activate NF-κB during organ culture with CsA. The concentration of CsA (10−5M), used in majority of the present in vitro study, is higher than the circulation level (0.3∼2.1×10−6M) in organ transplant recipients (Lukas et al., 2005). In the organ culture system, CsA 10−6M increased ETB mRNA expression (Fig. 1) but failed to induce the upregulation of ETB-mediated vasoconstriction (Zheng et al., 2013), which might be due to the fact that contractions induced by S6c (ETB-mediated) were more enhanced in small arteries than in larger arteries (Adner et al., 1998). The arteries used in the present study were the superior mesenteric arteries, where CsA 10−6M had no effect on ETB-mediated vasoconstriction. There is the possibility that the positive results of CsA 10−6M would be achieved by using the branches of superior mesenteric arteries where the contraction induced by S6c is more pronounced. Future study should be needed to address this question. In conclusion, the present study indicated that the intracellular ERK1/2, p38 MAPK, and NF-κB signaling pathways were involved in upregulation of ETB receptor induced by CsA, which might contribute to the development of CsA-induced hypertension. Understanding the molecular mechanisms how CsA leads to cardiovascular complications may provide the new options for the prevention and treatment for post-transplant hypertension.
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Introduction Alzheimer’s disease (AD) and stroke are the two most serious and debilitating neurological disorders in the United States. Stroke is the third leading cause of death in this country after cancer and heart disease (Stankowski and Gupta, 2011). Moreover, stroke is the leading cause of serious, long-term adult disability, accounting for $320.1 billion in health care costs (Mozaffarian et al., 2015). A recent statistical update by the American Heart Association Statistics Committee and Stroke Statistics Subcommittee states that about 795,000 people in the US experience a new or recurrent stroke per year (Mozaffarian et al., 2015). Statistical analyses demonstrate that 87% of all strokes are ischemic in nature (Lloyd-Jones et al., 2010), indicating that the presence of thrombosis, embolism, or systemic hypoperfusion can all lead to a reduction in blood flow to the brain, thereby decreasing the amounts of oxygen and glucose reaching this organ. Within minutes of interrupted blood flow, mitochondria are deprived of substrates, which prevents adenosine triphosphate generation and results in membrane depolarization. This leads to increased intracellular calcium and sodium concentrations followed by generation of free radicals and initiation of apoptosis (Doyle et al., 2008). Despite the severity of this condition, the only currently available FDA approved pharmacological treatment for ischemic stroke is recombinant tissue plasminogen activator (rtPA), which dissolves the clot and restores blood flow to the brain. Use of this treatment is limited by the relatively short window of time between infarct and treatment (3–4h) and the increased risk of subarachnoid hemorrhage (Micieli et al., 2009). A large number of other agents broadly classified as neuroprotective and intended to stop or slow the secondary damage associated with the ischemic cascade following stroke, have shown promise in the initial stages of research but have thus far failed to demonstrate usefulness in clinical studies because of meager efficacy or side effects (Otomo, 2003, Ly et al., 2006, Hishida, 2007, Ginsberg, 2009). A new approach is therefore needed, one which has the potential to restore blood flow and attenuate secondary damage to the penumbral area with fewer side effects and higher efficacy.