Inhibition of maternally expressed gene 3 attenuated lipopolysaccharide-induced apoptosis through sponging miR-21 in renal tubular epithelial cells
Authors: Guokun Wang
Dong Yan
Suxuan Liu
Leixi Xue
Yi Zhang
Ru Yang
Jian Wen
Zhichun Liu
Journal: Journal of Cellular Biochemistry (2018)
Discipline: MOLECULAR BIOLOGY & GENETICS
Keywords: acute kidney injury (AKI); apoptosis; maternally expressed gene 3 (MEG3); miR-21; programmed cell death protein 4 (PDCD4).
Affiliations: Department of Rheumatology; The Second Affiliated Hospital of Soochow University; Suzhou Jiangsu China, Department of Cardiovascular Surgery; Changhai Hospital, The Second Military Medical University; Shanghai China

Abstract:  Acute kidney injury (AKI) results in retention of waste products and dysregulation of extracellular volume and electrolytes, thus leading to a variety of complications. Recent advances in long noncoding RNAs suggested their close relationship with disease progression. In the current study, we investigated the role and mechanism of maternally expressed gene 3 (MEG3) on AKI pathogenesis. Real-time polymerase chain reaction found that the expression of MEG3 was significantly increased in both kidney tissues and TKPTS cells induced by lipopolysaccharide (LPS). Western blot assay showed that the expression of apoptosis regulator Bcl-2 was increased in MEG3-inhibited TKPTS cells. Flow cytometry assay confirmed that LPS-induced apoptosis was significantly attenuated after transfection of si-MEG3. The RNAhybrid informatics algorithm predicted that there was a strong binding capacity between miR-21 and MEG3. Luciferase reporter assay confirmed that MEG3 could function as a competing endogenous RNA of miR-21. The antiapoptotic effect of si-MEG3 could be neutralized by a miR-21 inhibitor, demonstrated by the decreased expression of Bcl-2 and flow cytometry results. Further investigation showed that programmed cell death protein 4 (PDCD4), a validated target of miR-21, was highly expressed in both injured kidney tissues and LPS-stimulated TKPTS cells. Meanwhile, the protein expression of PDCD4 was significantly reduced by inhibition of MEG3, but retrieved by coinhibition of MEG3 and miR-21. In conclusion, our results demonstrated that inhibition of MEG3 could attenuate LPS-induced apoptosis in TKPTS cells by regulating the miR-21/PDCD4 pathway, suggesting that the MEG3/miR-21/PDCD4 axis could be developed as a potential therapeutic target of AKI. 

Retracted: No

PubPeer comments:
 Fig 3D.  Flow cytometry analysis of apoptosis levels in TKPTS cells transfected with MEG3 siRNA (siu2010MEG3) or MEG3 siRNA miRu201021 inhibitor (siu2010MEG3 + miRu201021 inh) under LPS stimulation condition. The antiapoptotic effect of siu2010MEG3 could be neutralized by the miRu201021 inhibitor . I am unable to see any difference between the left-hand and right-hand panels, apart from the different quadrant counts. ![file] , 
 Thank you for the comments on our experimental results. We have examined the raw data immediately, and found that this is indeed our mistake. Due to unskilled analysis software, these two graphs were obtained from different cell subgroups of the same flow cytometry result (NC group). We analyze the data of si-MEG3+miR-21inh group just now, and upload the result. ![file] We will contact the journal editors to apologize for this mistake. We will also request the publication of errata information, and upload the right flow cytometry data. , 
 #2 Thank you for your reply. Could the authors help readers understand how the quadrant counts came to be different for the same results? , 
 This is our own mistake. When performing the flow cytometry assay, the technician would fine-tune the selected sub-cell populations of reference cells based on FSC and SSC data. Although the values of enter gates have not changed, the proportion of cells in each quadrant would have a small change. However, it does not affect the overall apoptosis level. , 
 #2 Thank you for this action! ,