Methylpiperidinopyrazole Attenuates Estrogen-Induced Mitochondrial Energy Production and Subsequent Osteoblast Maturation via an Estrogen Receptor Alpha-Dependent Mechanism

Abstract

An estrogen deficiency is the main cause of osteoporosis in postmenopausal women. In bone remodeling, estrogen receptors (ERs) can mediate estrogen-transducing signals. Methylpiperidinopyrazole (MPP) is a highly specific antagonist of ER-alpha (ERα). This study was designed to evaluate the effects of MPP on estrogen-induced energy production, subsequent osteoblast maturation, and the possible mechanisms. Exposure of primary osteoblasts isolated from neonatal rat calvarias to MPP did not affect cell morphology or survival. Estradiol can induce translocation of ERα into mitochondria from the cytoplasm. Interestingly, pretreatment of rat calvarial osteoblasts with MPP lowered estrogen-induced ERα translocation. Sequentially, estrogen-triggered expressions of mitochondrial energy production-linked cytochrome c oxidase (COX) I and COX II messenger (m)RNAs were inhibited following pretreatment with MPP. Consequently, MPP caused decreases in estrogen-triggered augmentation of the activities of mitochondrial respiratory complex enzymes and levels of cellular adenosine phosphate (ATP). During progression of osteoblast maturation, estrogen induced bone morphogenetic protein (BMP)-6 and type I collagen mRNA expressions, but MPP treatment inhibited such induction. Consequently, estrogen-induced osteoblast activation and mineralization were attenuated after exposure to MPP. Taken together, MPP suppressed estrogen-induced osteoblast maturation through decreasing chromosomal osteogenesis-related BMP-6 and type I collagen mRNA expressions and mitochondrial ATP synthesis due to inhibiting energy production-linked COX I and II mRNA expressions. MPP can appropriately be applied to evaluate estrogen-involved bioenergetics and osteoblast maturation.

Downregulation of long non-coding RNA PVT1 enhances fracture healing via regulating microRNA-497-5p/HMGA2 axis

“…In the current study, serum PVT1 levels were found to increase gradually over time after treatment for the fracture patients. It is known that the healing of fractures requires the proliferation of osteoblasts [ 29 ]. Considering the remarkable changes of serum PVT1 levels during fracture healing, its role in osteoblasts proliferation and apoptosis was further explored.…”

Naringin Improves Osteoblast Mineralization and Bone Healing and Strength through Regulating Estrogen Receptor Alpha-Dependent Alkaline Phosphatase Gene Expression

“…For every experiment, naringin with a purity > 95% was freshly prepared by dissolving it in dimethyl sulfoxide (DMSO). Human U-2 OS cells were exposed to 1, 10, and 100 μM naringin for 6, 12, and 24 h. MPP is a specific inhibitor of ERα . To inhibit activation of ERα, MPP, procured from Gibco-BRL, was prepared by dissolving it in DMSO.…”

“…In our previous study, administration of naringin, one of the bioactive ingredients in the water extract of Gusuibu, expanded trabecular bone numbers, bone strength, and bone mass in ovariectomized rats . An increase in ALP activity, a well-characterized biomarker of osteoblasts, corresponds to osteoblast activation and maturation. , ERα, compared to ERβ, plays a more significant role to mediate estrogen- and genistein-induced ATP production, osteogenesis, and bone formation. ,− Recently, we demonstrated that methylpiperidinopyrazole (MPP) can be used as a specific inhibitor of ERα to suppress estrogen-induced ATP synthesis and osteoblast maturation . However, how ERα contributes to naringin-induced improvements in bone healing and bone mass are still not well known.…”

Hypoxia Induced by Cobalt Chloride Triggers Autophagic Apoptosis of Human and Mouse Drug‐Resistant Glioblastoma Cells through Targeting the PI3K‐AKT‐mTOR Signaling Pathway

“…Morphologies and survival of human and mouse drug-sensitive and -resistant glioblastoma cells were analyzed according to a previously described method [ 27 ]. Drug-resistant glioblastoma cells (10 4 cells/well) were seeded in 12-well tissue culture plates overnight.…”

“…Hypoxic conditions in drug-resistant U87 MG-R and GL261-R glioblastoma cells were created by inducing HIF-1α [27]. Drug-resistant glioblastoma cells (10 4 cells/well) were seeded in 12-well tissue culture plates overnight.…”