eIF2α signaling regulates autophagy of osteoblasts and the development of osteoclasts in OVX mice

Li, Jie; Li, Xinle; Liu, Daquan; Hamamura, Kazunori; Wan, Qiaoqiao; Na, Sungsoo; Yokota, Hiroki; Zhang, Ping

doi:10.1038/s41419-019-2159-z

Cited by 70 publications

(46 citation statements)

References 58 publications

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“…Perk global knockout mice show severe osteopenia, suggesting that PERK is closely associated to bone metabolism 16 . Many researchers have reported the role of the PERK/eIF2α pathway in osteoblast differentiation, for example, salubrinal (selective eIF2α dephosphorylase inhibitor) can up-regulate ATF4 by promoting eIF2α phosphorylation, which cooperates with RUNX2 to regulate the expression of genes related to osteogenesis 44,45 . Whereas, the regulation impact of PERK pathway on osteoclast differentiation is less studied.…”

Section: Discussionmentioning

confidence: 99%

PERK controls bone homeostasis through the regulation of osteoclast differentiation and function

et al. 2020

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Osteoclasts are multinucleated giant cells with the ability to degrade bone tissue, and are closely related to abnormal bone metabolic diseases. Endoplasmic reticulum (ER) is an organelle responsible for protein modification, quality control, and transportation. The accumulation of unfolded or misfolded proteins in ER cavity induces ER stress. Double-stranded RNA-dependent protein kinase-like ER kinase (PERK) is an ER stress-sensing protein, which is ubiquitous in eukaryotic cells. Systemic PERK knockout mice show severe bone loss, suggesting that PERK is of great significance for maintaining the normal growth and development of bone tissue, but the role of PERK in osteoclastogenesis is still unclear. In this study, we found that PERK was significantly activated during RANKL-induced osteoclast differentiation; knockdown of PERK by siRNA and inhibition of PERK by GSK2606414, respectively, had significant negative regulatory effects on the formation and bone resorption of osteoclasts. PERK inhibitor GSK2606414 down-regulated the mRNA levels and protein expression of osteoclast differentiation marker genes, and inhibited RANKL-induced activation of Mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) pathways. Treatment with PERK inhibitor GSK2606414 in ovariectomized mouse model significantly suppressed bone loss and osteoclast formation. Thapsigargin activated ER stress to enhance autophagy, while GSK2606414 had a significant inhibitory effect on autophagy flux and autophagosome formation. Antioxidant N-acetylcysteine (NAC) could inhibit the expression of PERK phosphorylation, osteoclast-related proteins and autophagy-related proteins, but the use of PERK activator CCT020312 can reverse inhibition effect of NAC. Our findings demonstrate a key role for PERK in osteoclast differentiation and suggest its therapeutic potential.

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Section: Discussionmentioning

confidence: 99%

PERK controls bone homeostasis through the regulation of osteoclast differentiation and function

et al. 2020

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“…3 The distal femur was selected to determine the trabecular bone volume fraction (BV/ TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular separation (Tb.Sp). 47 Mice were imaged by peripheral dual-energy X-ray absorptiometry (pDEXA) in vivo. 36 The animal was anesthetized and placed in the prone position, and an image was acquired in ~5 minutes.…”

Section: Western Blot Analysismentioning

confidence: 99%

Mechanical loading stimulates bone angiogenesis through enhancing type H vessel formation and downregulating exosomal miR‐214‐3p from bone marrow‐derived mesenchymal stem cells

Wang

et al. 2020

FASEB j.

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Exosomes are important transporters of miRNAs, which play varying roles in the healing of the bone fracture. Angiogenesis is one of such critical events in bone healing, and we previously reported the stimulatory effect of mechanical loading in vessel remodeling. Focusing on type H vessels and exosomal miR-214-3p, this study examined the mechanism of loading-driven angiogenesis. MiRNA sequencing and qRT-PCR revealed that miR-214-3p was increased in the exosomes of the bone-losing ovariectomized (OVX) mice, while it was significantly decreased by knee loading. Furthermore, compared to the OVX group, exosomes, derived from the loading group, promoted the angiogenesis of endothelial cells. In contrast, exosomes, which were transfected with miR-214-3p, decreased the angiogenic potential. Notably, knee loading significantly improved the microvascular volume, type H vessel formation, and bone mineral density and contents, as well as BV/TV, Tb.Th, Tb.N, and Tb.Sp. In cell cultures, the overexpression of miR-214-3p in endothelial cells reduced the tube formation and cell migration. Collectively, this study demonstrates that knee loading promotes angiogenesis by enhancing the formation of type H vessels and downregulating exosomal miR-214-3p. K E Y W O R D S knee loading, MiRNA, osteoporosis, type H vessels, vessel remodeling 2 | WANG et Al. F I G U R E 1 Experimental setup, and the characterization of exosomes. A, Timeline (left) and loading site for knee loading (right, Bar = 1 cm). B, Morphology of exosomes with transmission electron microscopy, red arrows pointed to exosomes, Bar = 200 nm. C, The particle distribution was measured via nanoparticle tracking analysis. D, Protein markers of exosomes were detected by Western blot analysis. E, Representative images of HUVECs (red) incubated with PKH67-labelled exosomes (green) for 4 h. Bar = 50 µm

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“…To alleviate the surgery-linked pain, mice received 0.05 mg/kg buprenorphine hydrochloride every 8 h during the rst 3 days. Also, 1% pramoxine hydrochloride ointment was applied daily at the incision site [19,29].…”

Section: Ovariectomymentioning

confidence: 99%

“…For osteoblast differentiation, bone marrow-derived cells (2×10 6 cells/ml) were cultured in osteogenic differentiation medium (MEM-α containing 10% FBS, 10 nM dexamethasone, 50 μg/ml ascorbic acid, and 10 mM β-glycerophosphate). The medium was changed every 2 days, and cells were cultured for 14 days [29].…”

Section: Osteoblast Differentiation Assay and Alp Stainingmentioning

confidence: 99%

“…A Runx/Cbfβ complex promotes Wnt10b/β-catenin signaling and regulates the osteoblastadipocyte lineage [28]. We have shown that Wnt3a is involved in loading-driven bone formation and can potentially serve as a therapeutic target for osteoporosis [29]. However, little is known about the role of loading-driven Wnt/β-catenin signaling in the balance of cell fates towards osteoblasts and adipocytes in the pathogenesis of obesity-linked bone loss.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Loading Prevents Obesity-Associated Bone Loss by Maintaining the Balance between Adipocytes and Osteoblasts

Liu

et al. 2020

Preprint

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Background: Globally increasing obesity is closely linked to bone homeostasis. Maintaining the balance between differentiate of adipocytes and osteoblasts from bone marrow mesenchymal stem cells (BMSCs) is important for bone homeostasis. While mechanical loading has been shown to improve bone remodeling by promoting osteoblast differentiation, little is known about its effects on obesity-associated bone loss. Methods: Using obese mice induced by high-fat diet and ovariectomy (OVX), the effects of mechanical loading in a form of knee loading (1 N, 5 Hz, 6 min/day) was applied with for 4 weeks. The mice were sorted into five groups: standard diet control (SC), high-fat diet control (HF), HF and loading (HFL), HF and ovariectomy (HO), and HO and loading (HOL). Femurs were harvested for histomorphometry analysis. Bone marrow-derived cells were isolated to examine the banlance between differentiation of adipocytes and osteoblasts. Immunohistochemical analyses and Western blotting analyses were performed to evaluate markers for adipocytes, osteoblasts, and Wnt signaling.Results: High-fat diet presented higher body weight, body fat, and body mass index (BMI), as well as bone loss than standard diet, and the detrimental changes in OVX mice were even higher. The daily application of knee loading significantly decreased BMI, the numbers and perimeter of adipocytes, and the differentiation of adipocytes. The expression of C/EBPα and PPARγ were suppressed by knee loading. The loaded group also presented a significant increase in bone mineral density and contents, and the circumference of trabecular bone. Regarding osteoblasts, knee loading enhanced the number of osteoblasts on bone surface, differentiation of osteoblasts, and the level of Runx2 and ALP. Furthermore, Wnt signaling involved in the effect of knee loading on attenuating obesity-induced bone loss. Conclusions: This study supported evidence that knee loading offers a new therapeutic option to prevent obesity-related bone loss by altering the balance between adipocytes and osteoblasts in the bone marrow, and the effect is associated with Wnt signaling.

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eIF2α signaling regulates autophagy of osteoblasts and the development of osteoclasts in OVX mice

Cited by 70 publications

References 58 publications

PERK controls bone homeostasis through the regulation of osteoclast differentiation and function

PERK controls bone homeostasis through the regulation of osteoclast differentiation and function

Mechanical loading stimulates bone angiogenesis through enhancing type H vessel formation and downregulating exosomal miR‐214‐3p from bone marrow‐derived mesenchymal stem cells

Mechanical Loading Prevents Obesity-Associated Bone Loss by Maintaining the Balance between Adipocytes and Osteoblasts

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