SB 203580

SB203580, also called 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl) 1Himidazole [6], is a specific pyridinyl imidazole inhibitor of p38-MAPK (Mitogen-activated Protein Kinase) signaling pathway [1] [3]. It was competitive with ATP with a selectivity probably determined by nonconserved regions within or near the ATP binding pocket and a Ki of 21 nM [3]. It inhibits c-Raf with an IC50 of 2 mM in vitro [4].
p38 MAPK signaling pathway enables cells to generate a plethora of different effects to interpret a wide range of external signals and respond appropriately. There is a core of three protein kinases acting sequentially in this pathway to ensure the diversity and specificity in cellular outcomes [5].
Exposure to 30 mM SB203580 significantly decreased the resistance of L1210/VCR cells to vincristine accompanied by the LC50 value of vincristine changed from 3.2036±0.521 to 0.5576±0.082 mM. Exposure to 10 mM SB203580 slightly changed the value of the resistance index, accompanied by the LC50 values of SB203580 to sensitive L1210 cells and to resistant cells were 39.26±2.2 mM and 52.06±7.6 mM, respectively [1].
In vivo, administration of SB203580 alone 24 h before the permanent middle cerebral arterial occlusion abolished the isoflurane preconditioning-induced neuroprotection. After isoflurane exposure, administration of SB203580 decreased phosphorylated p38 MAPK. SB203580 inhibited anisomycin pretreatment-induced neuroprotection [6].
References:
[1]. Miroslav Baranclk, Vierka Bohacova, Janka Kvackajova, et al. SB203580, a specific inhibitor of p38-MAPK pathway, is a new reversal agent of P-glycoprotein-mediated multidrug resistance. European Journal of Pharmaceutical Sciences, 2001, 14: 29-36.
[2]. Shuqiu Zheng and Zhiyi Zuo. Isoflurane Preconditioning Induces Neuroprotection against Ischemia via Activation of P38 Mitogen-Activated Protein Kinases. Molecular Pharmacology, 2004, 65:1172-1180.
[3]. Peter R. Young, Megan M. McLaughlin, Sanjay Kumar, et al. Pyridinyl Imidazole Inhibitors of p38 Mitogen-activated Protein Kinase Bind in the ATP Site. The Journal of Biological Chemistry, 1997, 272(18): 12116-12121.
[4]. Clare A Hall-Jackson, Michel Goedert, Philip Hedge, et al. E€ect of SB 203580 on the activity of c-Raf in vitro and in vivo. Oncogene, 1999, 18: 2047-2054.
[5]. Ana Cuadrado and Angel R. Nebreda. Mechanisms and functions of p38 MAPK signalling. Biochem. J., 2010, 429: 403-417.
[6]. Shuqiu Zheng and Zhiyi Zuo. Isoflurane Preconditioning Induces Neuroprotection against Ischemia via Activation of P38 Mitogen-Activated Protein Kinases. Mol Pharmacol, 2004, 65: 1172-1180.

Regulation of the circadian oscillator in Xenopus retinal photoreceptors by protein kinases sensitive to the stress-activated protein kinase inhibitor, SB 203580.[Pubmed:15028715]

J Biol Chem. 2004 May 21;279(21):22738-46.

Circadian rhythms are generated by transcriptional and translational feedback loops. Stress-activated protein kinases (SAPKs) are known to regulate transcription factors in response to a variety of extracellular stimuli. In the present study, we examined whether the SAPKs play a role in the circadian system in cultured Xenopus retinal photoreceptor layers. A 6-h pulse of SB 203580, an inhibitor of SAPKs, reset the circadian rhythm of melatonin in a phase-dependent manner similar to dark pulses. This phase-shifting effect was dose-dependent over the range of 1-100 microm. Treatment with SB 203580 also affected light-induced phase shifts, and light had no effect on the circadian oscillator in the presence of 100 microm SB 203580. In-gel kinase assays showed that SB 203580 selectively inhibited a small group of protein kinases in the photoreceptor cells. These SB 203580-sensitive kinases correspond to two isoforms of phosphorylated p38 MAPK and three isoforms of c-Jun N-terminal kinase (JNK). Further in vitro study demonstrated that SB 203580 also inhibited casein kinase Iepsilon (CKIepsilon), which has been shown to regulate circadian rhythms in several organisms. However, a pharmacological inhibition of CKI reset the circadian oscillator in a phase-dependent manner distinct from that of SB 203580. This argues against a primary role of CKI in the phase-shifting effects of SB 203580. These results suggest that SB 203580 affects the circadian system by inhibiting p38 MAPKs or JNKs and that these protein kinases are candidate cellular signals in the regulation of the circadian oscillator in the Xenopus retinal photoreceptors.

Non-specific in vivo inhibition of CK1 by the pyridinyl imidazole p38 inhibitors SB 203580 and SB 202190.[Pubmed:19336000]

BMB Rep. 2009 Mar 31;42(3):142-7.

Small-molecule inhibitors of protein kinases have contributed immensely to our understanding of biological signaling pathways and have been exploited therapeutically for the treatment of cancers and other disease states. The pyridinyl imidazole compounds SB 203580 and SB 202190 were identified as ATP competitive antagonists of the p38 stress-activated protein kinases and have been widely used to elucidate p38-dependent cellular processes. Here, we identify SB 203580 and SB 202190 as potent inhibitors of stress-induced CREB phosphorylation on Serine 111 (Ser-111) in intact cells. Unexpectedly, we found that the inhibitory activity of SB 203580 and SB 202190 on CREB phosphorylation was independent of p38, but instead correlated with inhibition of casein kinase 1 (CK1) in vitro. The inhibition of CK1-mediated CREB phosphorylation by concentrations of pyridinyl imidazoles commonly employed to suppress p38, suggests that in some cases conclusions of p38-dependence derived solely from the use of these inhibitors may be invalid.

A Single Amino Acid Substitution Makes WNK4 Susceptible to SB 203580 and SB 202190.[Pubmed:21249167]

Open Med Chem J. 2010 Sep 3;4:57-61.

Regulation of the SLC12 family of membrane transporters including NCCT involves a scaffold of interacting proteins including the STE 20 kinase SPAK and the WNK kinases, WNK 1 and WNK 4, which are mutated in the hypertensive syndrome of pseudohypoaldosteronism type 2 (PHAII). WNK4 regulates NCCT by affecting forward trafficking to the surface membrane. Studies in Xenopus using kinase dead WNK4 site mutants have produced inconsistent results with regard to the necessity of kinase function for NCCT regulation. Dynamic inhibition of WNK4 by small molecules may bring clarity to this issue however WNK4 is naturally resistant to commercial MAP kinase inhibitors owing to steric constraints prohibiting entry of small molecules to the active site. Using an approach similar to that used in p38 and ERK, we show that a single substitution in WNK4 (T261G) dramatically enhances its susceptibility to the inhibitors SB 202190 and SB 203580.

Temporary blockade of contractility during reperfusion elicits a cardioprotective effect of the p38 MAP kinase inhibitor SB-203580.[Pubmed:15695561]

Am J Physiol Heart Circ Physiol. 2005 Jun;288(6):H2726-34.

p38 MAP kinase activation is known to be deleterious not only to mitochondria but also to contractile function. Therefore, p38 MAP kinase inhibition therapy represents a promising approach in preventing reperfusion injury in the heart. However, reversal of p38 MAP kinase-mediated contractile dysfunction may disrupt the fragile sarcolemma of ischemic-reperfused myocytes. We, therefore, hypothesized that the beneficial effect of p38 MAP kinase inhibition during reperfusion can be enhanced when contractility is simultaneously blocked. Isolated and perfused rat hearts were paced at 330 rpm and subjected to 20 min of ischemia followed by reperfusion. p38 MAP kinase was activated after ischemia and early during reperfusion (<30 min). Treatment with the p38 MAP kinase inhibitor SB-203580 (10 microM) for 30 min during reperfusion, but not the c-Jun NH(2)-terminal kinase inhibitor SP-600125 (10 microM), improved contractility but increased creatine kinase release and infarct size. Cotreatment with SB-203580 and the contractile blocker 2,3-butanedione monoxime (BDM, 20 mM) or the ultra-short-acting beta-blocker esmorol (0.15 mM) for the first 30 min during reperfusion significantly reduced creatine kinase release and infarct size. In vitro mitochondrial ATP generation and myocardial ATP content were significantly increased in the heart cotreated with SB-203580 and BDM during reperfusion. Dystrophin was translocated from the sarcolemma during ischemia and reperfusion. SB-203580 increased accumulation of Evans blue dye in myocytes depleted of sarcolemmal dystrophin during reperfusion, whereas cotreatment with BDM facilitated restoration of sarcolemmal dystrophin and mitigated sarcolemmal damage after withdrawal of BDM. These results suggest that treatment with SB-203580 during reperfusion aggravates myocyte necrosis but concomitant blockade of contractile force unmasks cardioprotective effects of SB-203580.

Inhibitors of p38 mitogen-activated protein kinase enhance proliferation of mouse neural stem cells.[Pubmed:18338804]

J Neurosci Res. 2008 Aug 1;86(10):2179-89.

The p38 mitogen-activated protein kinase (MAPK) is induced in response to environmental stress. Although p38 MAPK has been implicated in diverse cellular processes, including cell proliferation, differentiation, and survival of differentiated cells in the central nervous system (CNS), the expression profile and roles of p38 MAPK in the developing brain remain largely unknown. In the present study, we demonstrate that p38 MAPK is expressed predominantly in nestin-positive cells in the cerebral cortex in embryonic day 10 (E10) brain and that expression of the protein decreases gradually during development. To investigate the roles of p38 MAPK in the embryonic brain, two selective p38 MAPK inhibitors, SB202190 and SB203580, were added to the primary neuronal cultures from E10-E14 brains. After 7 days of exposure to these inhibitors, but not SB202474, a negative analog of SB203580, numerous large neurospheres were present. MAPK inhibitors also selectively increased the growth rate of neural stem cells (NSCs) purified from secondary neurospheres and the number of bromodeoxyuridine-positive NSCs. Thus, p38 MAPK inhibitors are potent stimulators of NSC proliferation, and p38 MAPK may be an intrinsic negative regulator of NSC proliferation during early brain development.

Specificity and mechanism of action of some commonly used protein kinase inhibitors.[Pubmed:10998351]

Biochem J. 2000 Oct 1;351(Pt 1):95-105.

The specificities of 28 commercially available compounds reported to be relatively selective inhibitors of particular serine/threonine-specific protein kinases have been examined against a large panel of protein kinases. The compounds KT 5720, Rottlerin and quercetin were found to inhibit many protein kinases, sometimes much more potently than their presumed targets, and conclusions drawn from their use in cell-based experiments are likely to be erroneous. Ro 318220 and related bisindoylmaleimides, as well as H89, HA1077 and Y 27632, were more selective inhibitors, but still inhibited two or more protein kinases with similar potency. LY 294002 was found to inhibit casein kinase-2 with similar potency to phosphoinositide (phosphatidylinositol) 3-kinase. The compounds with the most impressive selectivity profiles were KN62, PD 98059, U0126, PD 184352, rapamycin, wortmannin, SB 203580 and SB 202190. U0126 and PD 184352, like PD 98059, were found to block the mitogen-activated protein kinase (MAPK) cascade in cell-based assays by preventing the activation of MAPK kinase (MKK1), and not by inhibiting MKK1 activity directly. Apart from rapamycin and PD 184352, even the most selective inhibitors affected at least one additional protein kinase. Our results demonstrate that the specificities of protein kinase inhibitors cannot be assessed simply by studying their effect on kinases that are closely related in primary structure. We propose guidelines for the use of protein kinase inhibitors in cell-based assays.

Direct inhibition of cyclooxygenase-1 and -2 by the kinase inhibitors SB 203580 and PD 98059. SB 203580 also inhibits thromboxane synthase.[Pubmed:9786874]

J Biol Chem. 1998 Oct 30;273(44):28766-72.

The kinase inhibitors SB 203580 and PD 98059 have been reported to be specific inhibitors of the 38- and 42/44-kDa mitogen-activated protein kinase (MAPK) pathways, respectively. In this study, the two inhibitors were found to decrease platelet aggregation induced by low concentrations of arachidonic acid, suggesting that they also interfere with the metabolism of arachidonic acid to thromboxane A2. In support of this, SB 203580 and PD 98059 inhibited the conversion of exogenous [3H]arachidonic acid to [3H]thromboxane in intact platelets. Measurement of platelet cyclooxygenase-1 activity following immunoprecipitation revealed that SB 203580 and PD 98059 are direct inhibitors of this enzyme. Both compounds were shown to inhibit purified cyclooxygenase-1 and -2 by a reversible mechanism. In addition, SB 203580 (but not PD 98059) inhibited platelet aggregation induced by prostaglandin H2 and the conversion of prostaglandin H2 to thromboxane A2 in intact platelets. SB 203580 also inhibited this pathway in platelet microsome preparations, suggesting a direct inhibitory effect on thromboxane synthase. These results demonstrate that direct effects of the two kinase inhibitors on active arachidonic acid metabolites have to be excluded before using these compounds for the investigation of MAPKs in signal transduction pathways. This is of particular relevance to studies on the regulation of cytosolic phospholipase A2 as these two MAPKs are capable of phosphorylating cytosolic phospholipase A2, thereby increasing its intrinsic activity.

Role for p38 mitogen-activated protein kinase in platelet aggregation caused by collagen or a thromboxane analogue.[Pubmed:8636072]

J Biol Chem. 1996 Mar 22;271(12):6586-9.

p38 mitogen-activated protein kinase (MAPK) was identified in platelets on the basis of (a) its reactivity with antibodies to C-terminal and N-terminal peptides, and (b) its ability to activate MAPK-activated protein kinase-2, which phosphorylates the small heat shock protein, hsp27. p38 MAPK was activated in platelets by collagen fibers, a collagen-related cross-linked peptide, thrombin, or the thromboxane analogue U46619. A highly specific inhibitor of p38 MAPK, a pyridinyl imidazole known as SB203580, inhibited the platelet enzyme in vitro (IC50 approximately 0.5 microM). At similar concentrations it also inhibited agonist-stimulated phosphorylation of hsp27 in platelets, and platelet aggregation and secretion induced by minimal aggregatory concentrations of collagen or U46619, but not thrombin. Inhibition of aggregation was overcome by increasing agonist dose. SB203580 might act by inhibiting thromboxane generation, but this was only inhibited by 10-20% at low agonist concentrations. p38 MAPK provides a crucial signal, which is necessary for aggregation caused by minimal concentrations of collagen fibers or U46619. Thrombin or high doses of these agonists generate signals that bypass the enzyme, or render the enzyme no longer rate-limiting.

SB 203580 (RWJ 64809) is a selective and ATP-competitive p38 MAPK inhibitor with IC50s of 50 nM and 500 nM for SAPK2a/p38 and SAPK2b/p38β2, respectively. SB 203580 inhibits LCK, GSK3β and PKBα with IC50s of 100-500-fold higher than that for SAPK2a/p38. SB 203580 does not disrupt JNK activity and is an autophagy and mitophagy activator.

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