Isoflavones rich cowpea and vitamin D induces the proliferation and differentiation of human osteoblasts via BMP‐2/Smad pathway activation: Mechanistic approach

Abstract

Isoflavones, such as Genistein (Ge) and Daidzein (Dz) are widely studied Phytoestrogens with potent anti-osteoporotic and good antioxidant activity. Cowpea is one such legume having high isoflavone content and hence we aimed at studying the beneficial effects of the isoflavones isolated from cowpea as it is widely accepted staple food in India. Previously, we reported the effect of Cowpea isoflavones (CP) and Vitamin D (VD) owing to its ability of improving the osteoporotic condition in a diet induced osteoporotic rat model. In the present study, we tried to explore the underlying mechanism of CP and VD along with positive controls Dz and Ge in influencing the functions of human osteoblasts at cellular level.Initially, MG-63 cells were assessed for the expression of genes involved in BMP-2 signaling pathway, like Bone morphogenic protein (BMP-2), transcription factor Osterix (OSX), total and phosphorylated Smad 1/5/8 levels and osteoblast specific genes levels namely Alkaline phosphatase (ALP), Osteopontin (OPN), and Collagen by immunoblot, flow cytometry, and quantitative RT-PCR studies. All the levels that were upregulated with the initial exposure of the compounds got inhibited after Noggin exposure a specific BMP-2 antagonist both at protein level and m-RNA level, except OSX where the expression was totally hindered in CP and Ge treated groups alone. Hence, CP and VD activate BMP-2/Smad signaling pathway and promote further proliferation and differentiation of osteoblasts. Therefore, results prove that isoflavones isolated from cowpea could be used in treating bone-related disorders. K E Y W O R D SALP, BMP, collagen, MG-63 Osteoblasts, Noggin, Osteopontin, Smad 1/5/8

The Beneficial and Adverse Effects of Phytoestrogens

“…We also briefly summarized the structure and grouping of estrogens and phytoestrogens, especially the bioavailability of isoflavonoids [35,36]. Here, we also showed the effect of phytoestrogens on signal transduction pathways based on recent studies on molecular biology [23,44,45,49,51,58,98].…”

“…The isoflavonoids and vitamin D of cowpea daidzein and genistein together activate the BMP-2/Smad (bone morphogenetic protein-2 growth factor/Smad signal transduction pathways) signaling pathway of osteoblasts in osteogenesis and promote further proliferation and differentiation of osteoblasts. These results showed that isoflavones (daidzein and genistein) isolated from cowpea can be used in the treatment of bone disorders [57,58].…”

“…It affects osteoblast function, stimulates cell proliferation, and promotes the differentiation of osteoblasts. Daidzein acts by stimulating the activation of the BMP-2/Smads pathway [58,98].…”

Beneficial regulation of vitamin D3-rich extract from the processing by-products of Penaeus sinensis on preosteoblastic MC3T3-E1 cells and improvement of bone health in VD-deficient mice

“…Several studies have shown that VD has both anabolic and catabolic effects in bone homeostasis by stimulating differentiation, mineralization and bone formation of osteoblasts. [12][13][14] Although the precise effects of VD on osteoblasts may vary with treatment time, dosage, and source of osteoblasts, 15 VD can regulate specific protein expression and signaling pathways related to osteoblast proliferation and differentiation, such as Wnt signaling, 16 bone morphogenetic proteins (BMPs), 17 runt-related transcription factor 2 (Runx2), 14,18 MARK signaling, 19 osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa B ligand (RANKL) signaling pathway. 12,20 Among BMPs, BMP2 is the most effective inducer for osteoblast differentiation and performs a crucial osteogenic function.…”