Pellegrini Gretel G, Morales Cynthya C, Wallace Taylor C, Plotkin Lilian I, Bellido Teresita
Department of Anatomy & Cell Biology, School of Medicine, Indiana University, Indianapolis, IN 46202, USA.
Roudebush Veterans Administration Medical Center, Indianapolis, IN 46202, USA.
Nutrients. 2016 Jul 11;8(7):423. doi: 10.3390/nu8070423.
Oats contain unique bioactive compounds known as avenanthramides (AVAs) with antioxidant properties. AVAs might enhance the endogenous antioxidant cellular response by activation of the transcription factor Nrf2. Accumulation of reactive oxygen species plays a critical role in many chronic and degenerative diseases, including osteoporosis. In this disease, there is an imbalance between bone formation by osteoblasts and bone resorption by osteoclasts, which is accompanied by increased osteoblast/osteocyte apoptosis and decreased osteoclast apoptosis. We investigated the ability of the synthethic AVAs 2c, 2f and 2p, to 1-regulate gene expression in bone cells, 2-affect the viability of osteoblasts, osteocytes and osteoclasts, and the generation of osteoclasts from their precursors, and 3-examine the potential involvement of the transcription factor Nrf2 in these actions. All doses of AVA 2c and 1 and 5 µM dose of 2p up-regulated collagen 1A expression. Lower doses of AVAs up-regulated OPG (osteoprotegerin) in OB-6 osteoblastic cells, whereas 100 μM dose of 2f and all concentrations of 2c down-regulated RANKL gene expression in MLO-Y4 osteocytic cells. AVAs did not affect apoptosis of OB-6 osteoblastic cells or MLO-Y4 osteocytic cells; however, they prevented apoptosis induced by the DNA topoisomerase inhibitor etoposide, the glucocorticoid dexamethasone, and hydrogen peroxide. AVAs prevented apoptosis of both wild type (WT) and Nrf2 Knockout (KO) osteoblasts, demonstrating that AVAs-induced survival does not require Nrf2 expression. Further, KO osteoclast precursors produced more mature osteoclasts than WT; and KO cultures exhibited less apoptotic osteoclasts than WT cultures. Although AVAs did not affect WT osteoclasts, AVA 2p reversed the low apoptosis of KO osteoclasts. These in vitro results demonstrate that AVAs regulate, in part, the function of osteoblasts and osteocytes and prevent osteoblast/osteocyte apoptosis and increase osteoclast apoptosis; further, these regulatory actions are independent of Nrf2.
燕麦含有独特的具有抗氧化特性的生物活性化合物,称为燕麦酰胺(AVAs)。AVAs可能通过激活转录因子Nrf2来增强内源性抗氧化细胞反应。活性氧的积累在包括骨质疏松症在内的许多慢性和退行性疾病中起关键作用。在这种疾病中,成骨细胞形成骨与破骨细胞吸收骨之间存在失衡,同时伴有成骨细胞/骨细胞凋亡增加和破骨细胞凋亡减少。我们研究了合成的AVAs 2c、2f和2p的能力,一是调节骨细胞中的基因表达,二是影响成骨细胞、骨细胞和破骨细胞的活力以及破骨细胞前体产生破骨细胞的过程,三是检查转录因子Nrf2在这些作用中的潜在参与情况。所有剂量的AVA 2c以及1和5 μM剂量的2p均上调了胶原蛋白1A的表达。较低剂量的AVAs上调了OB-6成骨细胞中的骨保护素(OPG),而100 μM剂量的2f和所有浓度的2c下调了MLO-Y4骨细胞中的核因子κB受体活化因子配体(RANKL)基因表达。AVAs不影响OB-6成骨细胞或MLO-Y4骨细胞的凋亡;然而,它们能防止由DNA拓扑异构酶抑制剂依托泊苷、糖皮质激素地塞米松和过氧化氢诱导的凋亡。AVAs可防止野生型(WT)和成核因子相关因子2(Nrf2)基因敲除(KO)的成骨细胞凋亡,表明AVAs诱导的细胞存活不需要Nrf2表达。此外,KO破骨细胞前体比WT产生更多成熟破骨细胞;并且KO培养物中凋亡破骨细胞比WT培养物少。尽管AVAs不影响WT破骨细胞,但AVA 2p可逆转KO破骨细胞的低凋亡率。这些体外结果表明AVAs部分调节成骨细胞和骨细胞的功能,防止成骨细胞/骨细胞凋亡并增加破骨细胞凋亡;此外,这些调节作用独立于Nrf2。