scholarly journals miR-431-5p regulates cell proliferation and apoptosis in fibroblast-like synoviocytes in rheumatoid arthritis by targeting XIAP

2020 ◽  
Author(s):  
Yuejiao Wang ◽  
Kailin Zhang ◽  
Xiaowei Yuan ◽  
Neili Xu ◽  
Shuai Zhao ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Cell Cycle ◽  
Cell Proliferation ◽  
Real Time ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Proliferation And Apoptosis ◽  
Synovial Tissues ◽  
Proliferation Assays ◽  
Fibroblast Like Synoviocytes

Abstract Background miR-431-5p is dysregulated in various cancers and plays an important function in the development of cancer. However, its role in fibroblast-like synoviocytes (FLSs) in patients with rheumatoid arthritis (RA) remains to be understood. Methods Quantitative real-time polymerase chain reaction was used to detect the relative expression of miR-431-5p in synovial tissues and FLSs. Cell proliferation assays helped examine RA FLS proliferation. Flow cytometry was performed to determine apoptosis and cell cycle progression in RA FLSs. We used dual-luciferase assays to determine the correlation between miR-431-5p and its putative target, X-linked inhibitor of apoptosis (XIAP). Quantitative real-time PCR and western blotting were used to measure XIAP levels in synovial tissues and transfected RA FLSs. Results miR-431-5p was downregulated in synovial tissues and FLSs of patients with RA. Upregulation of miR-431-5p prohibited cell proliferation and the G0/G1-to-S phase transition, but promoted apoptosis in RA FLSs; while miR-431-5p inhibition showed the opposite results. miR-431-5p directly targeted XIAP in RA FLSs, and reversely correlated with XIAP levels in synovial tissues. Notably, XIAP silencing partially restored the effects of miR-431-5p inhibition in RA FLSs. Conclusion miR-431-5p regulates cell proliferation, apoptosis，and cell cycle of RA FLSs by targeting XIAP, suggesting its potential in the treatment of RA.

scholarly journals miR-431-5p regulates cell proliferation and apoptosis in fibroblast-like synoviocytes in rheumatoid arthritis by targeting XIAP

2020 ◽  
Author(s):  
Yuejiao Wang ◽  
Kailin Zhang ◽  
Xiaowei Yuan ◽  
Neili Xu ◽  
Shuai Zhao ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Cell Cycle ◽  
Cell Proliferation ◽  
Real Time ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Proliferation And Apoptosis ◽  
Synovial Tissues ◽  
Proliferation Assays ◽  
Fibroblast Like Synoviocytes

Abstract Background miR-431-5p is dysregulated in various cancers and plays an important function in the development of cancer. However, its role in fibroblast-like synoviocytes (FLSs) in patients with rheumatoid arthritis (RA) remains to be understood.Methods Quantitative real-time polymerase chain reaction was used to detect the relative expression of miR-431-5p in synovial tissues and FLSs. Cell proliferation assays helped examine RA FLS proliferation. Flow cytometry was performed to determine apoptosis and cell cycle progression in RA FLSs. We used dual-luciferase assays to determine the correlation between miR-431-5p and its putative target, X-linked inhibitor of apoptosis (XIAP). Quantitative real-time PCR and western blotting were used to measure XIAP levels in synovial tissues and transfected RA FLSs.Results miR-431-5p was downregulated in synovial tissues and FLSs of patients with RA. Upregulation of miR-431-5p prohibited cell proliferation and the G0/G1-to-S phase transition, but promoted apoptosis in RA FLSs; while miR-431-5p inhibition showed the opposite results. miR-431-5p directly targeted XIAP in RA FLSs, and reversely correlated with XIAP levels in synovial tissues. Notably, XIAP silencing partially restored the effects of miR-431-5p inhibition in RA FLSs.Conclusion miR-431-5p regulates cell proliferation, apoptosis，and cell cycle of RA FLSs by targeting XIAP, suggesting its potential in the treatment of RA.

scholarly journals miR-431-5p regulates cell proliferation and apoptosis in fibroblast-like synoviocytes in rheumatoid arthritis by targeting XIAP

2020 ◽  
Author(s):  
Yuejiao Wang ◽  
Kailin Zhang ◽  
Xiaowei Yuan ◽  
Neili Xu ◽  
Shuai Zhao ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Cell Cycle ◽  
Cell Proliferation ◽  
Real Time ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Proliferation And Apoptosis ◽  
Synovial Tissues ◽  
Proliferation Assays ◽  
Fibroblast Like Synoviocytes

Abstract BackgroundmiR-431-5p is dysregulated in various cancers and plays an important function in the development of cancer. However, its role in fibroblast-like synoviocytes (FLSs) in patients with rheumatoid arthritis (RA) remains to be understood.MethodsQuantitative real-time polymerase chain reaction was used to detect the relative expression of miR-431-5p in synovial tissues and FLSs. Cell proliferation assays helped examine RA FLS proliferation. Flow cytometry was performed to determine apoptosis and cell cycle progression in RA FLSs. We used dual-luciferase assays to determine the correlation between miR-431-5p and its putative target, X-linked inhibitor of apoptosis (XIAP). Quantitative real-time PCR and western blotting were used to measure XIAP levels in synovial tissues and transfected RA FLSs.ResultsmiR-431-5p was downregulated in synovial tissues and FLSs of patients with RA. Upregulation of miR-431-5p prohibited cell proliferation and the G0/G1-to-S phase transition, but promoted apoptosis in RA FLSs; while miR-431-5p inhibition showed the opposite results. miR-431-5p directly targeted XIAP in RA FLSs, and reversely correlated with XIAP levels in synovial tissues. Notably, XIAP silencing partially restored the effects of miR-431-5p inhibition in RA FLSs.ConclusionmiR-431-5p regulates cell proliferation, apoptosis，and cell cycle of RA FLSs by targeting XIAP, suggesting its potential in the treatment of RA.

scholarly journals miR-431-5p regulates cell proliferation and apoptosis in fibroblast-like synoviocytes in rheumatoid arthritis by targeting XIAP

2020 ◽  
Vol 22 (1) ◽  
Author(s):  
Yuejiao Wang ◽  
Kailin Zhang ◽  
Xiaowei Yuan ◽  
Neili Xu ◽  
Shuai Zhao ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Cell Cycle ◽  
Cell Proliferation ◽  
Real Time ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Proliferation And Apoptosis ◽  
Synovial Tissues ◽  
Proliferation Assays ◽  
Fibroblast Like Synoviocytes

Abstract Background miR-431-5p is dysregulated in various cancers and plays an important function in the development of cancer. However, its role in fibroblast-like synoviocytes (FLSs) in patients with rheumatoid arthritis (RA) remains to be understood. Methods Quantitative real-time polymerase chain reaction was used to detect the relative expression of miR-431-5p in synovial tissues and FLSs. Cell proliferation assays helped examine RA FLS proliferation. Flow cytometry was performed to determine apoptosis and cell cycle progression in RA FLSs. We used dual-luciferase assays to determine the correlation between miR-431-5p and its putative target, X-linked inhibitor of apoptosis (XIAP). Quantitative real-time PCR and western blotting were used to measure XIAP levels in synovial tissues and transfected RA FLSs. Results miR-431-5p was downregulated in synovial tissues and FLSs of patients with RA. Upregulation of miR-431-5p prohibited cell proliferation and the G0/G1-to-S phase transition but promoted apoptosis in RA FLSs, while miR-431-5p inhibition showed the opposite results. miR-431-5p directly targeted XIAP in RA FLSs and reversely correlated with XIAP levels in synovial tissues. Notably, XIAP silencing partially restored the effects of miR-431-5p inhibition in RA FLSs. Conclusion miR-431-5p regulates cell proliferation, apoptosis, and cell cycle of RA FLSs by targeting XIAP, suggesting its potential in the treatment of RA.

scholarly journals Uridine Diphosphate (UDP) Promotes Rheumatoid Arthritis Through P2Y6 Activation

2020 ◽  
Author(s):  
Hongxing Wang ◽  
Hui Wu ◽  
Kehua Fang ◽  
Xiaotian Chang
Keyword(s):  
Rheumatoid Arthritis ◽  
Cell Proliferation ◽  
Real Time ◽  
Proinflammatory Cytokines ◽  
Uridine Diphosphate ◽  
Synovial Fluids ◽  
Synovial Tissues ◽  
And Migration ◽  
G Protein Coupled ◽  
Fibroblast Like Synoviocytes

Abstract Background: Uridine diphosphate (UDP) is an extracellular nucleotide signaling molecule implicated in diverse biological processes via specific activation of pyrimidinergic receptor P2Y, G Protein-Coupled, 6 (P2Y6). There is very little knowledge about the function and mechanism of UDP in rheumatoid arthritis (RA).Methods: This study used a quasi-targeted liquid chromatography-mass spectrometry (LC-MS) approach to investigate the unique expression of metabolites in RA synovial fluids (SF) (n = 10) with samples from osteoarthritis (OA) as controls (n = 10). RA fibroblast-like synoviocytes (FLSs) were collected from synovial tissues (n = 5) and cultured with UDP or MRS2578, a P2Y6 antagonist, and FLSs from OA were used as controls (n = 5). Rats with collagen-induced arthritis (CIA) were injected with UDP, MRS2578 or both (n = 9 for each group). P2Y6 expression was examined using real-time PCR, Western blotting and immunohistochemistry. Cell proliferation, apoptosis and migration of RA FLSs were measured using CCK-8 assay, real-time cell analysis, flow cytometry, wound healing assay and Transwell assay, respectively. The UDP levels in the culture medium, synovial fluid (n = 36) and peripheral blood (n = 36) of RA and CIA rats were measured using a Transcreener UDP Assay. Levels of proinflammatory cytokines were measured using a flow assay. Interleukin-6 (IL-6) levels were measured using ELISA and flowResults：LC-MS analysis detected significantly increased UDP levels in RA SF compared with OA SF, and the level was positively correlated with anticyclic citrullinated peptide (anti-CCP) and rheumatoid factor (RF) levels in RA. The increased UDP concentration was verified in the blood and synovial fluids of RA patients compared with samples from OA patients and healthy volunteers, respectively. UDP stimulated cell proliferation, migration and IL-6 secretion in RA FLSs and inhibited their apoptosis in culture, and MRS2578 inhibited these effects of UDP. UDP injection accelerated CIA and stimulated IL-6 production rather than other proinflammatory cytokines in the rat model, but simultaneous injection of MRS2578 suppressed these effects and alleviated CIA. P2Y6 expression was increased in RA and CIA synovial tissues.Conclusion: These results suggest that UDP is highly expressed in RA and stimulates RA pathogenesis by promoting P2Y6 activities to increase IL-6 production.

scholarly journals Uridine Diphosphate Promotes Rheumatoid Arthritis Through P2Y6 Activation

2021 ◽  
Vol 12 ◽  
Author(s):  
Hongxing Wang ◽  
Hui Wu ◽  
Kehua Fang ◽  
Xiaotian Chang
Keyword(s):  
Rheumatoid Arthritis ◽  
Cell Proliferation ◽  
Real Time ◽  
Proinflammatory Cytokines ◽  
Uridine Diphosphate ◽  
Synovial Fluids ◽  
Synovial Tissues ◽  
And Migration ◽  
G Protein Coupled ◽  
Fibroblast Like Synoviocytes

BACKGROUND: Uridine diphosphate (UDP) is an extracellular nucleotide signaling molecule implicated in diverse biological processes via specific activation of pyrimidinergic receptor P2Y, G Protein-Coupled, 6 (P2Y6). There is very little knowledge about the function and mechanism of UDP in rheumatoid arthritis (RA).METHODS: This study used a quasi-targeted liquid chromatography-mass spectrometry (LC-MS) approach to investigate the unique expression of metabolites in RA synovial fluids (SF) (n = 10) with samples from osteoarthritis (OA) as controls (n = 10). RA fibroblast-like synoviocytes (FLSs) were collected from synovial tissues (n = 5) and cultured with UDP or MRS2578, a P2Y6 antagonist, and FLSs from OA were used as controls (n = 5). Rats with collagen-induced arthritis (CIA) were injected with UDP, MRS2578 or both (n = 9 for each group). P2Y6 expression was examined using real-time PCR, Western blotting and immunohistochemistry. Cell proliferation, apoptosis and migration of RA FLSs were measured using CCK-8 assay, real-time cell analysis, flow cytometry, wound healing assay and Transwell assay, respectively. The UDP levels in the culture medium, synovial fluid (n = 36) and peripheral blood (n = 36) of RA and CIA rats were measured using a Transcreener UDP Assay. Levels of proinflammatory cytokines were measured using a flow assay. Interleukin-6 (IL-6) levels were measured using ELISA and flow.RESULTS: LC-MS analysis detected significantly increased UDP levels in RA SF compared with OA SF, and the level was positively correlated with anticyclic citrullinated peptide (anti-CCP) and rheumatoid factor (RF)levels in RA. The increased UDP concentration was verified in the blood and synovial fluids of RA patients compared with samples from OA patients and healthy volunteers, respectively. UDP stimulated cell proliferation, migration and IL-6 secretion in RA FLSs and inhibited their apoptosis in culture, and MRS2578 inhibited these effects of UDP. UDP injection accelerated CIA and stimulated IL-6 production rather than other proinflammatory cytokines in the rat model, but simultaneous injection of MRS2578 suppressed these effects and alleviated CIA. P2Y6 expression was increased in RA and CIA synovial tissues.CONCLUSION: These results suggest that UDP is highly expressed in RA and stimulates RA pathogenesis by promoting P2Y6 activities to increase IL-6 production.

scholarly journals LncRNA EPIC1 Promotes Cancer Cell Proliferation and Inhibits Apoptosis in Gallbladder Cancer Interacting with lncRNA LET

2020 ◽  
Author(s):  
Changbo Fu ◽  
Lei Nie ◽  
Tao Yin ◽  
Xuan Xu ◽  
weijun lu
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Gallbladder Cancer ◽  
Cancer Cell ◽  
Cell Cycle Progression ◽  
Human Cancer ◽  
Cancer Cell Proliferation ◽  
Cycle Progression ◽  
Tumor Tissues ◽  
Proliferation And Apoptosis

Abstract Background: LncRNA EPIC1 is likely involved in human cancer by promoting cell cycle progression. Our study was carried out to investigate the involvement of EPIC1 in gallbladder cancer (GBC). Methods: Expression levels of EPIC1 in two types of tissues (GBC and paracancerous) and plasma were measured by performing qPCR. GBC-SD and SGC-996 cells were transfected with LET and EPIC1 expression vectors.Results: In the preset study we found that EPIC1 was upregulated in tumor tissues than in paracancerous tissues of GBC patients, and plasma levels of EPIC1 were significantly correlated with levels of EPIC1 in tumor tissues. LncRNA LET was downregulated in tumor tissues than in paracancerous tissues and was inversely correlated with EPIC1 in both tumor tissues and paracancerous tissues. Overexpression of EPIC1 led to downregulated LET, and LET overexpression also mediated the downregulation of EPIC1. EPIC1 led to accelerated GBC cell proliferation and inhibited apoptosis. Overexpression of LET played opposites roles. In addition, overexpression of LET also attenuated the effects of EPIC1 overexpression on cancer cell proliferation and apoptosis. Conclusion: Therefore, therefore, lncRNA EPIC1 may promote cancer cell proliferation and inhibit apoptosis in GBC by interacting with LET.

scholarly journals Uridine Diphosphate (UDP) Promotes Rheumatoid Arthritis Through P2Y6 Activation

2020 ◽  
Author(s):  
Hongxing Wang ◽  
Hui Wu ◽  
Kehua Fang ◽  
Xiaotian Chang
Keyword(s):  
Rheumatoid Arthritis ◽  
Cell Proliferation ◽  
Synovial Fluid ◽  
Real Time ◽  
Uridine Diphosphate ◽  
Collagen Induced Arthritis ◽  
Synovial Tissues ◽  
And Migration ◽  
G Protein Coupled ◽  
Fibroblast Like Synoviocytes

Abstract Background: Uridine diphosphate (UDP) is an extracellular nucleotide signaling molecule implicated in diverse biological processes via specific activation of the metabotropic pyrimidine and purine nucleotide receptor pyrimidinergic receptor P2Y, G Protein-Coupled, 6 (P2Y6).Methods: This study used a quasi-targeted liquid chromatography-mass spectrometry (LC-MS) approach to investigate the unique expression of metabolites in rheumatoid arthritis (RA) synovial fluid (SF) (n=10) with samples from osteoarthritis (OA) as controls (n=10). RA fibroblast-like synoviocytes (FLSs) were collected from synovial tissues and cultured with UDP or MRS2578, P2Y6 antagonist, and FLSs from OA was used as controls. Rats with collagen-induced arthritis (CIA) were established and injected with UDP or MRS2578 or both. P2Y6 expression was examined using real-time PCR, Western blotting and Immunohistochemistry. Cell proliferation, apoptosis and migration of FLSs were measured using CCK-8 assay, real-time cell analysis, flow cytometry, the wound healing assay and transwell assay. The concentration of UDP in culture medium, synovial fluid and peripheral blood RA and CIA rats was measured using a Transcreener UDP Assay, IL-6 was measured using ELISA and flow assay, and other pro-inflammatory cytokines was measured using Th1/Th2 Subgroup Detection Kit. Results: LC-MS analysis showed that the UDP level is not only higher in RA SF than in OA SF but also positively correlated with anticyclic citrullinated peptide (anti-CCP) and rheumatoid factor (RF) levels in RA. The increased UDP concentration was verified in the plasma and SF samples of RA patients (n=36) and healthy volunteers (n=36), and the levels were significantly correlated with RF and anti-CCP level in the samples. The study also found that UDP stimulated the cell proliferation, migration and interleukin-6 (IL-6) secretion of RA FLSs and inhibited their apoptosis in the culture. The P2Y6 antagonist MRS2578 inhibited this effect of UDP in the culture. UDP injection accelerated the development of collagen-induced arthritis (CIA) in a rat model and stimulated IL-6 production, but simultaneous injection of MRS2578 suppressed these effects and alleviated CIA. P2Y6 expression was increased in RA and CIA synovial tissues and was unaltered by UDP treatment. UDP treatment and P2Y6 activity didn’t change levels of other proinflammatory cytokines in cultured FLSs and CIA rats.Conclusion: These results suggest that UDP is highly expressed in RA and stimulates RA pathogenesis by promoting P2Y6 activities to increase IL-6 production.

scholarly journals CircASH2L facilitates tumor-like biologic behaviours and inflammation of fibroblast-like synoviocytes via miR-129-5p/HIPK2 axis in rheumatoid arthritis

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Xia Li ◽  
Meiting Qu ◽  
Jie Zhang ◽  
Kuanyin Chen ◽  
Xianghui Ma
Keyword(s):  
Rheumatoid Arthritis ◽  
Cell Cycle ◽  
Flow Cytometry ◽  
Western Blot ◽  
Cell Cycle Progression ◽  
Circular Rna ◽  
Cycle Progression ◽  
Qrt Pcr ◽  
Cycle Arrest ◽  
Fibroblast Like Synoviocytes

Abstract Background Previous study showed that circular RNA Absent-Small-Homeotic-2--Like protein (circASH2L) was higher in rheumatoid arthritis (RA) patients. However, the roles and mechanisms of circASH2L in RA progression remain unclear. Methods Levels analysis was conducted using western blot and qRT-PCR. The proliferation, apoptosis, cell cycle progression, migration, invasiveness, and inflammation of RA fibroblast-like synoviocytes (RA-FLSs) were determined via MTT, flow cytometry, western blot, transwell, and ELISA assays. Results CircASH2L knockdown in RA-FLSs suppressed cell proliferative, migratory, and invasive capacities, triggered cell cycle arrest, promoted apoptosis, and inhibited inflammation. Mechanistically, circASH2L targeted miR-129-5p, and repression of miR-129-5p abolished the functions of circASH2L silencing on the growth, motility, and inflammation of RA-FLSs. Besides, miR-129-5p was found to directly target HIPK2, and suppressed the tumor-like biologic behaviors and inflammation of RA-FLSs via regulating HIPK2. Importantly, we proved that circASH2L could modulate HIPK2 expression via miR-129-5p. Conclusion CircASH2L promoted RA-FLS growth, motility, and inflammation through miR-129-5p/HIPK2 axis.

scholarly journals Resveratrol promotes apoptosis and G2/M cell cycle arrest of fibroblast-like synoviocytes in rheumatoid arthritis through regulation of autophagy and the serine-threonine kinase-p53 axis

2021 ◽  
Author(s):  
Shu Li ◽  
Jinfeng Du ◽  
Haina Gan ◽  
Jinwei Chen ◽  
Yang Zhou ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Survival ◽  
Akt Pathway ◽  
Serine Threonine Kinase ◽  
Threonine Kinase ◽  
Proliferation And Apoptosis ◽  
Fibroblast Like Synoviocytes

IntroductionResveratrol, a polyphenol extracted from many plant species, has emerged as a promising pro-apoptotic agent in various cancer cells. However, the role of resveratrol in cell proliferation and apoptosis of fibroblast-like synoviocytes in rheumatoid arthritis (RA-FLS) is not fully understood. The study was aimed at elucidating the role of resveratrol in cell proliferation and apoptosis of RA-FLS and the underlying molecular mechanism.Material and methodsCultured RA-FLSs were subjected to tumour necrosis factor  (TNF-). The cell proliferation was measured by Cell Counting Kit-8 assay. Cell apoptosis and cell cycle of RA-FLSs were determined by flow cytometry. The levels of apoptosis or autophagy or cell cycle-related protein were detected by immunoblot analysis.ResultsIn our study, we confirmed that resveratrol reversed TNF- mediated cell proliferation in RA-FLS. Meanwhile, resveratrol blocked cells at the G2/M stage and reduced the ratio of S phase cells through upregulation of p53 and consequently led to apoptotic cell death. Quite interestingly, we found that resveratrol reversed TNF--induced autophagy. Inhibition of autophagy by resveratrol or autophagy inhibitor or Beclin-1 siRNA suppressed TNF- mediated cell survival and promoted cell apoptosis. However, the autophagy inducer rapamycin (RAPA) reversed the effect of resveratrol on autophagy and cell proliferation. Mechanistic studies revealed that resveratrol inhibited the activation of the phosphoinositide 3-kinases/serine-threonine kinase (PI3K/AKT) pathway. Inhibition of PI3K/AKT pathway by inhibitor LY294002 or resveratrol increased the expression of p53 and decreased the expression of cycle protein (cyclin B1), which further led to block cells in the G2/M arrest.ConclusionsOur preliminary study indicated that resveratrol may suppress RA-FLS cell survival and promote apoptosis at least partly through regulation of autophagy and the AKT-p53 axis.

scholarly journals STAU2 protein level is controlled by caspases and the CHK1 pathway and regulates cell cycle progression in the non-transformed hTERT-RPE1 cells

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Lionel Condé ◽  
Yulemi Gonzalez Quesada ◽  
Florence Bonnet-Magnaval ◽  
Rémy Beaujois ◽  
Luc DesGroseillers
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Cell Proliferation ◽  
Dna Damage ◽  
Steady State ◽  
Posttranscriptional Regulation ◽  
Cell Cycle Progression ◽  
Rna Binding ◽  
Regulation Of Gene Expression ◽  
Cycle Progression

AbstractBackgroundStaufen2 (STAU2) is an RNA binding protein involved in the posttranscriptional regulation of gene expression. In neurons, STAU2 is required to maintain the balance between differentiation and proliferation of neural stem cells through asymmetric cell division. However, the importance of controlling STAU2 expression for cell cycle progression is not clear in non-neuronal dividing cells. We recently showed that STAU2 transcription is inhibited in response to DNA-damage due to E2F1 displacement from theSTAU2gene promoter. We now study the regulation of STAU2 steady-state levels in unstressed cells and its consequence for cell proliferation.ResultsCRISPR/Cas9-mediated and RNAi-dependent STAU2 depletion in the non-transformed hTERT-RPE1 cells both facilitate cell proliferation suggesting that STAU2 expression influences pathway(s) linked to cell cycle controls. Such effects are not observed in the CRISPR STAU2-KO cancer HCT116 cells nor in the STAU2-RNAi-depleted HeLa cells. Interestingly, a physiological decrease in the steady-state level of STAU2 is controlled by caspases. This effect of peptidases is counterbalanced by the activity of the CHK1 pathway suggesting that STAU2 partial degradation/stabilization fines tune cell cycle progression in unstressed cells. A large-scale proteomic analysis using STAU2/biotinylase fusion protein identifies known STAU2 interactors involved in RNA translation, localization, splicing, or decay confirming the role of STAU2 in the posttranscriptional regulation of gene expression. In addition, several proteins found in the nucleolus, including proteins of the ribosome biogenesis pathway and of the DNA damage response, are found in close proximity to STAU2. Strikingly, many of these proteins are linked to the kinase CHK1 pathway, reinforcing the link between STAU2 functions and the CHK1 pathway. Indeed, inhibition of the CHK1 pathway for 4 h dissociates STAU2 from proteins involved in translation and RNA metabolism.ConclusionsThese results indicate that STAU2 is involved in pathway(s) that control(s) cell proliferation, likely via mechanisms of posttranscriptional regulation, ribonucleoprotein complex assembly, genome integrity and/or checkpoint controls. The mechanism by which STAU2 regulates cell growth likely involves caspases and the kinase CHK1 pathway.

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