Basic nutritional investigationCinnamon polyphenols regulate S100β, sirtuins, and neuroactive proteins in rat C6 glioma cells
Introduction
Plant-derived natural polyphenols represent a wide variety of compounds that are enriched in fruits, vegetables, wine, tea, extra virgin olive oil, chocolate, and other plant products. Accumulating evidence suggests that cinnamon has many health benefits when used both in herbal medicine and as a spice [1]. We have isolated and characterized a polyphenol-rich water-soluble extract from cinnamon polyphenols (CP), that is high in doubly-linked polyphenol type-A polymers [2], [3] that has insulin-potentiating [2], antioxidant [4], and antiinflammatory proprieties [5], [6]. In human studies, water-soluble CP have been shown to reduce fasting blood sugar levels in prediabetic patients with metabolic syndrome [7], improve antioxidant status, decrease risk factors associated with diabetes and cardiovascular diseases [4], and improve insulin sensitivity in women with polycystic ovary syndrome [8]. Metabolic syndrome is associated with insulin resistance, elevated glucose and lipids, inflammation, decreased antioxidant activity, increased weight gain, and increased glycation of proteins. CP have been shown to improve all of these variables in in vitro, animal, and/or human studies [1].
CP also have been reported to exert neuroprotective effects, such as inhibiting tau aggregation associated with Alzheimer’s disease [9], reducing cell swelling associated with ischemic injury [10], attenuating mitochondrial dysfunction in ischemic injury [10], [11], and improving glutamate uptake following ischemia-like injury in vitro [11]. Moreover, an aqueous extract of cinnamon has been shown to inhibit Aβ oligomer formation and ameliorate Alzheimer’s disease symptoms [12]. Although polyphenols have been reported to exert neuroprotective actions against injury induced by neurotoxins, and display the ability to suppress neuroinflammation [13], it is not clear whether such polyphenols exert protective effects by modulating the functions of other prosurvival proteins, including S100β, sirtuins, Bcl-xl, as well as intracellular signaling pathways mediated by mitogen-activated protein kinases (MAPKs), and nuclear factor-κB (NF-κB).
S100β, is a calcium-binding protein primarily expressed in the central nervous system (CNS), and synthesized and secreted by astrocytes [14]. Increasing evidence suggests that S100β plays a double function as an intracellular regulator and an extracellular signal of the CNS. S100β is found in the cytoplasm in a soluble form and also is associated with intracellular membranes, centrosomes, microtubules, and type III intermediate filaments [15]. Within cells, it is involved in the regulation of cell proliferation, differentiation, shape, Ca2+ homeostasis, protein phosphorylation, transcription, enzyme activity, and metabolism [14]. When secreted into the extracellular medium, S100β exerts regulatory effects on neighboring cells including astrocytes, neurons, and microglia. At nanomolar levels, S100β has neurotrophic activity in the extracellular medium, but at micromolar levels it stimulates apoptosis [16], [17]. The mechanisms of regulating S100β secretion are not completely understood and appear to be related to many factors [14], such as the proinflammatory cytokines, tumor necrosis factor alpha (TNF-α) [18], interleukin (IL)-1β [19], and metabolic stress [20]. Moreover, a previous study suggested that S100β secretion involves the MAPK pathway and apparently could involve NF-κB signaling [19].
A Sirts activator, resveratrol, has been shown to increase glutamate uptake and S100β secretion in cortical astrocyte cultures [21]. It also has a protective effect against acute H2O2-induced oxidative stress in astrocyte cultures, enhancing the impaired S100β secretion [22]. Sirtuins (Sirt), a family of nicotinamide adenine nucleotide (NAD)-dependent deacetylases, are implicated in energy metabolism and lifespan. Sirtuins are novel targets for Alzheimer’s disease and other neurodegenerative disorders. Sirt1 has been found to protect cell DNA damage and reduce apoptotic death in vitro [23]. Sirt2 activity plays a key role in maintaining the survival of glioma cells [24], and Sirt3 acts as a survival factor playing an essential role to protect neurons under excitotoxic injury [25].
The C6 glioma cell line exhibits many astrocytic features, and has been used widely to characterize the mechanisms of an astrocytic model system, such as the study of neurotrophic actions [26], nerve growth factors [27], and insulin-like growth factors [28]. Here, we investigated the in vitro effects of CP on the intracellular expression and the extracellular secretion of S100β in rat C6 glioma cultures. We also evaluated whether CP regulates Sirtuin 1, 2, and 3 expression. Additionally, the antiapoptotic protein, Bcl-xl, inflammatory factor, TNF-α, transcription factor, phospho-NF-κB (p-NF-κB) p65, MAPK phospho-p38, extracellular signal-regulated protein (ERK) and mitogen-activated protein and kinase-activated protein (MAPKAPK2) kinases also were investigated.
Section snippets
Cinnamon polyphenols
The aqueous extract of cinnamon contained 0.74% of a type A tetramer, cassiatannin A, with a molecular weight of 1152 and 2.30% of cinnamtannin D1, molecular weight 864, 0.72% of cinnamtannin B1, and 0.22 and 0.12% of two type A trimer isomers, whose exact structure is not known, molecular weight 864. The total percent of the type A polymers that were quantitated was 4.10%. Type A polymers were identified using electrospray ionization mass spectrometry analyses using an LCQ ion trap instrument
CP enhanced the intracellular expression and the extracellular secretion of S100β in C6 cells
To investigate whether CP increases S100β secretion in C6 cells, extracellular S100β content was measured after exposure to CP for 24 h by immunoprecitation and subsequent immunoblotting (Fig. 1). After CP incubation, a significant increase in S100β secretion was observed with both concentrations of CP (147% and 243% of controls; P < 0.05, respectively). Increased secretion of S100β also was observed after 4 h of CP treatment (data not shown). Furthermore, intracellular S100β expression was
Discussion
CP have been reported previously to exert neuroprotective effects [9], [10], [11], [33]. This study adds to mounting evidence that CP increases intracellular S100β expression and extracellular S100β secretion in C6 glial cultures. Additionally, CP also increased the levels of sirtuins, phosphorylation of MAPK, and decreased levels of proinflammatory proteins.
S100β is involved in the regulation of cell proliferation, differentiation, shape, Ca2+ homeostasis, protein phosphorylation,
Conclusions
The results of the current investigation, in conjunction with the findings from our previous studies, indicate that CP may exert neuroprotective effects in astroglial cells by upregulating prosurvival proteins and decreasing proinflammatory proteins.
Acknowledgments
This work was supported in part by a USDA Cooperative Research and Development Agreement (CRADA No.58-3K95-7-1184) with Integrity Nutraceuticals International, Spring Hill, TN. BQ has a joint appointment with the U.S. Department of Agriculture and Integrity Nutraceutical International (Spring Hill, TN). Mention of trade names or commercial products is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.
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2022, Translational Research in AnatomyCitation Excerpt :In astrocytes, S100B is located within the cytoplasm and nucleus, where it regulates various cellular activities [78]. It binds to crucial synaptic proteins such as toll-like receptor 4 (TLR4) (Fig. 1), thereby inhibiting their phosphorylation [79], and signal transduction is affected via the mitogen-activated protein kinases (MAPK) and nuclear factor kappa light chain enhancer of activated B cells (NF-kB) pathways [80]. The mechanism of secretion and action of S100B remains unclear [81] however, it may be associated to different factors such as interleukin β, tumor necrosis factor alpha α-1, the proinflammatory cytokines and metabolic stress [82]].
Cinnamon, a promising prospect towards Alzheimer's disease
2018, Pharmacological ResearchCitation Excerpt :It has been verified that S100B is associated with the principle mechanisms of neurodegeneration in AD [153]. Similarly, different mixture of cinnamon enriched with type A PPs (10 and 20 μg/ml), exhibited significant neuroprotective effects in C6 rat glioma cells by upregulation of SIRT1, activation of MAPK pathways and suppression of pro-inflammatory cytokines [159]. Researchers illustrated that AD comprises strong interactions with chronic neuroinflammation [67].
Effects of aqueous cinnamon extract on chemically-induced carcinoma of hamster cheek pouch mucosa
2017, Biochemistry and Biophysics ReportsCitation Excerpt :Koppikar et al. [9] reported that aqueous cinnamon extract (ACE) from the bark of Cinnamomum cassia causes apoptosis in human cervical cancer cell line through loss of mitochondrial membrane potential. Cinnamon polyphenols was found to exert neuroprotective effects in glial cells by the regulation of Bcl-2 family members and enhancing the expression of protein coding gene SIRT1 during oxidative stress [10,11]. In 2015, Assadollahi et al. [12] investigated the effects of Cinnamon zeylanicum aqueous extract on the human myelocytic leukemia cell line.
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2017, Trends in Food Science and TechnologyCitation Excerpt :It may be a promising natural in avoiding or delaying the progression of these diseases (Ho et al., 2013; Modi et al., 2015). Cinnamon polyphenols may exert neuroprotective effects as showed by Qin, Panickar, and Anderson (2014a, b) because they protects cells from oxidative stress. In an in vitro and in vivo study, it was demonstrated that an aqueous cinnamon extract from bark can be used as an efficacious treatment of Alzheimer's and Parkinson's diseases (Frydman-Marom et al., 2011; Shaltiel-Karyo et al., 2012).
Cinnamon polyphenols attenuate the hydrogen peroxide-induced down regulation of S100β secretion by regulating sirtuin 1 in C6 rat glioma cells
2014, Life SciencesCitation Excerpt :CP also have been reported to exert their neuroprotective effects, such as inhibiting tau aggregation associated with Alzheimer's disease (Peterson et al., 2009), blocking cell swelling associated with strokes (Panickar et al., 2009) and improving glutamate uptake following ischemia-like injury in vitro (Panickar et al., 2012). We recently reported that CP upregulate pro-survival proteins, activate MAPK pathways, and decrease pro-inflammatory cytokines in C6 glioma cells (Qin B et al., 2014). The aim of this study was to investigate if CP attenuate H2O2-induced oxidative stress in C6 glioma cells and also to study the mechanisms underlying the effects of CP.