LncRNA NEAT1 controls the lineage fates of BMSCs during skeletal aging by impairing mitochondrial function and pluripotency maintenance

Hengguo Zhang,Weiwen Zhu,Jiyu Chen,Hongbing Jiang,Xiang Li,Bang Li,Laikui Liu,Yu Fu,Ziji Ling,Ping Zhang,Rongyao Xu,Jie Cheng,Zhili Xin

doi:10.1038/s41418-021-00858-0

Abstract

Aged bone marrow mesenchymal stem cells (BMSCs) exhibit aberrant self-renewal and lineage specification, which contribute to imbalanced bone-fat and progressive bone loss. In addition to known master regulators of lineage commitment, it is crucial to identify pivotal switches governing the specific differentiation fate of aged BMSCs. Here, we profiled differences in epigenetic regulation between adipogenesis and osteogenesis and identified super-enhancer associated lncRNA nuclear-enriched abundant transcript 1 (NEAT1) as a key bone-fat switch in aged BMSCs. We validated that NEAT1 with high enhancer activity was transcriptionally activated by ATF2 and directed aged BMSCs to a greater propensity to differentiate toward adipocytes than osteoblasts by mediating mitochondrial function. Furthermore, we confirmed NEAT1 as a protein-binding scaffold in which phosphorylation modification of SOX2 Ser249/250 by CDK2 impaired SOX2/OCT4 complex stability and dysregulated downstream transcription networks of pluripotency maintenance. In addition, by sponging miR-27b-3p, NEAT1 upregulated BNIP3L, BMP2K, and PPARG expression to shape mitochondrial function and osteogenic/adipogenic differentiation commitment, respectively. In extracellular communication, NEAT1 promoted CSF1 secretion from aged BMSCs and then strengthened osteoclastic differentiation by extracellular vesicle delivery. Notably, Neat1 small interfering RNA delivery induced increased bone mass in aged mice and decreased fat accumulation in the bone marrow. These findings suggest that NEAT1 regulates the lineage fates of BMSCs by orchestrating mitochondrial function and pluripotency maintenance, and might be a potential therapeutic target for skeletal aging.

Highlights

Age-related osteoporosis is characterized by net bone loss, a proinflammatory microenvironment, and excessive adipose tissue accumulation [1,2,3]
nuclear-enriched abundant transcript 1 (NEAT1) was simultaneously upregulated in the nucleus and cytoplasm in aged bone marrow mesenchymal stem cells (BMSCs) (Fig. S1K–L). These findings reveal that osteogenesis involves the induction of many genes that are already active in undifferentiated BMSCs, whereas adipogenesis is characterized by BMSCs markers loss and NEAT1_1 upregulation
After 6 weeks of administration, important organs were collected for observation (Fig. S8C). qRT-PCR was used to detect the expression of Neat1, bmp2k, pparg, bnip3l, csf1, and miR-27b-3p in BMSCs of young mice, aged mice, and si-NEAT1treated aged mice, and the results showed NEAT1 downregulation, miR-27b-3p upregulation, and target genes downregulation in aged mice treated with si-NEAT1 (Fig. S8D)

Summary

Introduction

Age-related osteoporosis is characterized by net bone loss, a proinflammatory microenvironment, and excessive adipose tissue accumulation [1,2,3]. Adipocyte-enriched bone marrow during skeletal aging is primarily attributed to dysfunctional self-renewal and pluripotent differentiation of bone marrow mesenchymal stem cells (BMSCs) that are more inclined to differentiate into adipocytes rather than osteoblasts [4,5,6]. BMSCs lineage specification via transcriptional control is strictly orchestrated by key molecular signals to maintain bone-fat balance [7,8,9]. RUNX2 and ALPL serve as crucial transcription factors (TFs) to initiate the osteoblastic lineage, while PPARγ and PGC1-α are master regulators of adipogenic differentiation. This does not explain the inverse relationship between osteoblastic lineage commitment accompanied by a coordinated inhibition of adipogenesis [10,11,12]. It is essential to explore the potential molecular switches that govern

Methods

Results

Conclusion