<p>Knockdown of hsa_circ_0059955 Induces Apoptosis and Cell Cycle Arrest in Nucleus Pulposus Cells via Inhibiting <em>Itchy E3 Ubiquitin Protein Ligase</em></p>

Abstract

Background: Circular RNAs (circRNAs) play an important role in the progression of intervertebral disc (IVD) degeneration (IVDD). Using bioinformatics analysis, we have found that the expression of circRNA hsa_circ_0059955 was significantly downregulated in IVDD tissues. However, the relevant mechanism of hsa_circ_0059955 in the progression of IVDD remains unclear. Methods: CCK-8 and flow cytometry assays were used to evaluate cell proliferation and apoptosis. In addition, Western blot assay was used to detect the expressions of ITCH, p73, CDK2 in nucleus pulposus (NP) cells. Moreover, a puncture-induced IVDD rat model was established to explore the role of hsa_circ_0059955 in IVDD. Results: The level of hsa_circ_0059955 was significantly decreased in IVDD tissues from IVDD patients. Itchy E3 ubiquitin protein ligase (ITCH) is the host gene of hsa_circ_0059955, and downregulation of hsa_circ_0059955 significantly decreased the expression of ITCH in NP cells. In addition, downregulation of hsa_circ_0059955 markedly inhibited proliferation and induced apoptosis and cell cycle arrest in NP cells. Moreover, in vivo study illustrated that overexpression of hsa_circ_0059955 ameliorated IVDD in rats. Conclusion: Downregulation of hsa_circ_0059955 could induce apoptosis and cell cycle arrest in NP cells in vitro, while overexpression of hsa_circ_0059955 attenuated the IVDD in a puncture-induced rat model in vivo. Therefore, hsa_circ_0059955 might serve as a therapeutic target for the treatment of IVDD.

Circular RNAs in Intervertebral Disc Degeneration: An Updated Review

“…Like circITCH, circ_0059955 is another circRNA transcribed from the host gene ITCH (Itchy E3 ubiquitin protein ligase). Kong et al (2020) demonstrated that circ_0059955 was significantly downregulated in IDD samples. Knockdown of circ_0059955 suppressed ITCH expression and inhibited proliferation, induced cell cycle arrest and promoted apoptosis of NP cells.…”

Noncoding RNAs in skeletal development and disorders

“…Numerous studies have demonstrated that ncRNAs have critical functions in modulating IVD development (as discussed in recently published review articles [ 115 , 125 ]). Besides, some ncRNAs, including miR-15a-5p [ 126 ], miR-19b-3p [ 127 ], miR-25 [ 128 ], miR-26a-5p [ 129 ], miR-105-5p [ 130 ], miR-130b [ 131 ], miR-145-5p [ 132 ], miR-195 [ 133 ], miR-345-3p [ 134 ], miR-495-3p [ 135 ], miR-499a-5p [ 136 ], miR-502 [ 137 ], miR-660 [ 138 ], miR-2355-5p [ 139 ], miR-4478 [ 140 ], circKIF18A [ 141 ], hsa_circ_0083756 [ 142 ], hsa_circ_0059955 [ 143 ], circSPG21 [ 144 ], circPKNOX1 [ 145 ], circ-FAM169A [ 146 ], circERCC2 [ 147 ], circ-4099 [ 148 ], lncRNA XIST [ 149 ], and LncRNA NR2F1-AS1 [ 132 ] are revealed to be differently expressed in NP tissues and cells from IVDD patients. However, the investigation into the different mechanisms of IVDD in genetic animal models is extremely limited.…”

Nucleus pulposus cells degeneration model: a necessary way to study intervertebral disc degeneration

“…Gene knockout and microbial co-culture are newer methods for NPC degeneration models. Kong et al [91] constructed a degenerative cell model by down-regulating the hsa_circ_0059955 gene of normal mouse NPCs and inducing NPC apoptosis and cell cycle arrest. In 2020, He et al [92] found that Cutibacterium acnes induce NPC degeneration by activating the NOD-like receptor thermal protein domain associated protein 3(NLRP3(-dependent pathway.…”