Autophagy regulates exosome secretion in rat nucleus pulposus cells via the RhoC/ROCK2 pathway

Hu, Shun-Qi; Zhang, Qichen; Meng, Qingbing; Hu, Annan; Zou, Jiapeng; Li, Xilei

doi:10.1016/j.yexcr.2020.112239

Cited by 16 publications

(12 citation statements)

References 42 publications

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“…This finding provided us new information about why autophagy may stimulate exosomes release of NPCs. 45 Our work also has some limitations. First, only rat NPCs were tested in this study.…”

Section: Discussionmentioning

confidence: 97%

Autophagy‐activated nucleus pulposus cells deliver exosomal miR‐27a to prevent extracellular matrix degradation by targeting MMP‐13

Zhang

et al. 2020

Journal Orthopaedic Research

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Although autophagy may be beneficial for maintaining the metabolic balance of the extracellular matrix (ECM) in the nucleus pulposus (NP) and its vitality under inflammation, the underlying mechanism still remains unclear. A previous study found that autophagy activation stimulated the release of exosomes in normal chondrocytes, which are located in a similar avascular environment and share many common features with those of nucleus pulposus cells (NPCs). This study explored the protective effect on matrix degradation in the NP by exosomes derived from autophagy-activated NPCs and exosomal microRNAs. NPCs-derived exosomes (NPCs-Exos) were isolated from culture medium of either normal NPCs or rapamycin-treated NPCs and quantified by nanoparticle tracking analysis. The effect of rapamycin-treated NPC-derived exosomes on NPCs were assessed by coculture with interleukin 1β (IL-1β)-stimulated NPCs. After examination of six major proteinases of the ECM, matrix metalloproteinase 13 (MMP-13) was chosen for further study. miR-27a, which targets MMP-13, was investigated through previous studies and bioinformatics tool. The levels of miR-27a were upregulated in both rapamycintreated NPCs and their exosomes, compared to the control. When exosomal miR-27a was transferred into NPCs, it alleviated IL-1β-induced degradation of the NPC ECM by targeting MMP-13. Autophagy activation may promote the release of NPCs-derived exosomes and thereby prevent the NPC matrix from degradation.Autophagy activation also alleviates intervertebral disc degeneration (IDD), at least partly via exosomal miR-27a, which restrains MMP-13 expression under IL-1β stimulation. Our work elucidates a new mechanism for how autophagy may participate in preventing IDD, which may be a promising therapeutic strategy.

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“…This finding provided us new information about why autophagy may stimulate exosomes release of NPCs. 45 Our work also has some limitations. First, only rat NPCs were tested in this study.…”

Section: Discussionmentioning

confidence: 97%

Autophagy‐activated nucleus pulposus cells deliver exosomal miR‐27a to prevent extracellular matrix degradation by targeting MMP‐13

Zhang

et al. 2020

Journal Orthopaedic Research

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“…Moreover, Rab27a, 27b ( Ostrowski et al, 2010 ), Rab35 ( Hsu et al, 2010 ), and Ral GTPases ( Pathak and Dermardirossian, 2013 ) function in the attachment of MVBs to the plasma membrane. Finally, Rab5a ( Gorji-Bahri et al, 2021 ), Rab13 ( Hinger et al, 2020 ), and RhoC ( Hu et al, 2020 ) promote the secretion of exosomes.…”

Section: Small Gtpases In Membrane Trafficking Pathwaysmentioning

confidence: 99%

Ubiquitination-Dependent Regulation of Small GTPases in Membrane Trafficking: From Cell Biology to Human Diseases

Lei

Wang

Zhang

et al. 2021

Front. Cell Dev. Biol.

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Membrane trafficking is critical for cellular homeostasis, which is mainly carried out by small GTPases, a class of proteins functioning in vesicle budding, transport, tethering and fusion processes. The accurate and organized membrane trafficking relies on the proper regulation of small GTPases, which involves the conversion between GTP- and GDP-bound small GTPases mediated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). Emerging evidence indicates that post-translational modifications (PTMs) of small GTPases, especially ubiquitination, play an important role in the spatio-temporal regulation of small GTPases, and the dysregulation of small GTPase ubiquitination can result in multiple human diseases. In this review, we introduce small GTPases-mediated membrane trafficking pathways and the biological processes of ubiquitination-dependent regulation of small GTPases, including the regulation of small GTPase stability, activity and localization. We then discuss the dysregulation of small GTPase ubiquitination and the associated human membrane trafficking-related diseases, focusing on the neurological diseases and infections. An in-depth understanding of the molecular mechanisms by which ubiquitination regulates small GTPases can provide novel insights into the membrane trafficking process, which knowledge is valuable for the development of more effective and specific therapeutics for membrane trafficking-related human diseases.

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“…Interestingly, the activation of exosome release has been reported in cells under inflammatory conditions. The via intercellular transportation associated with the Rhoassociated coiled-coil containing protein kinase 2 (ROCK2)/ RhoC signaling pathway (24). However, the mechanism underlying the inflammation induced-exosome release from NPCs remained unclear.…”

Section: Discussionmentioning

confidence: 99%

TNF-α-stimulated nucleus pulposus cells induce cell apoptosis through the release of exosomal miR-16 targeting IGF-1 and IGF-1R in rats

Zhang¹,

Zou²,

Hu³

et al. 2021

Ann Transl Med

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Background: Exosomes may contain excess cellular components released by cells in response to harmful external stimuli to maintain cellular homeostasis. Inflammatory cytokines, such as tumor necrosis factoralpha (TNF-α), can induce cell apoptosis, alter cellular component expression levels, and stimulate exosome release. In this study, we examined whether exosomes released from nucleus pulposus cells (NPCs) under inflammatory conditions could induce normal NP cell apoptosis in rats and its underlining mechanism.Methods: Exosomes were isolated from TNF-α-treated NPCs and used to treat normal NPCs. The effects were assessed by flow cytometry and western blot analysis. Anti-apoptotic insulin-like growth factor-1 (IGF-1) expression in NPCs was assessed by western blot analysis. Given the exosomal miRNAs might be the key factors of exosomes, bioinformatics approaches and quantitative real-time polymerase chain reaction (qRT-PCR) were used to identify IGF-1-regulating micro RNAs (miRNAs), including miR-16. Luciferase reporter assay assessed miR-16 regulation of IGF-1 and IGF-1 receptor (IGF-1R). NPCs were transfected with miR-16 mimic, and exosomes were applied to normal NPCs. NPCs were pretreated with 10 ng/mL TNF-α, transfected with miR-16 inhibitors, and the exosomes were isolated. Cell and exosome miR-16 levels were detected by qRT-PCR. Western blot analysis determined IGF-1, IGF-1R, and apoptotic marker levels in exosome-treated NPCs.Results: Exosomes from TNF-α-treated NPCs induced apoptosis in normal NPCs and repressed IGF-1 expression. Exosomal miR-16 regulated IGF-1 and induced NPC apoptosis. The dual-luciferase reporter assay revealed that miR-16 binds the 3' untranslated regions (3'-UTRs) of IGF-1 and IGF-1R. Exosomal miR-16 repressed IGF-1 and the IGF-1R/phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway which therefore induced NPC apoptosis. Rescue experiments using miR-16 inhibitors further validated these findings. Conclusions:The inflammatory factor TNF-α stimulated exosome release from NPCs, which induced the apoptosis of normal NPCs through the actions of exosomal miR-16. Exosomal miR-16 directly repressed the anti-apoptotic IGF-1/IGF-1R pathway, increasing the apoptosis of NPCs.

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Autophagy regulates exosome secretion in rat nucleus pulposus cells via the RhoC/ROCK2 pathway

Cited by 16 publications

References 42 publications

Autophagy‐activated nucleus pulposus cells deliver exosomal miR‐27a to prevent extracellular matrix degradation by targeting MMP‐13

Autophagy‐activated nucleus pulposus cells deliver exosomal miR‐27a to prevent extracellular matrix degradation by targeting MMP‐13

Ubiquitination-Dependent Regulation of Small GTPases in Membrane Trafficking: From Cell Biology to Human Diseases

TNF-α-stimulated nucleus pulposus cells induce cell apoptosis through the release of exosomal miR-16 targeting IGF-1 and IGF-1R in rats

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