The Role Of TFEB Modified By STUB1 Regulates Autophagy In IMN And Its Mechanism

Objectives: The molecular chaperone protein STUB1(STIP1 homologous and U box containing protein1,STUB1),also known as CHIP(carboxy terminus of Hsp70 interacting protein,CHIP).About the new type of auxiliary chaperone protein,the structure of STUB1 is similar to the RING finger of the ubiquitin ligase E3 in the ubiquitin-proteasome system(UPS)and also has the alike function of E3.STUB1 can ubiquitinate the target protein and regulate the biological function of the target protein.Transcription factor EB(TFEB)belongs to the Mi TF / TFE(microphthalmia-transcription factor E)family.Its phosphorylation level affects its own transcriptional activity,and its structural changes and regulatory functions are strictly regulated by a series of protein molecules.Multiple signaling pathways such as phosphatidylinositol 3-kinase(PI3K)/ protein kinase B(PKB)pathway,ROS pathway,mammalian target of rapamycin,m TOR)pathway,nuclear factor-?B(NF-?B)pathway and so on,can activate autophagy response.TFEB works through these pathways.Autophagy,as a natural defense mechanism that is highly conserved in eukaryotic cells,plays an important "correction" role in the occurrence and development of various kidney diseases.The sign of autophagosome formation is the formation of microtubule-associated protein 1 light chain 3(LC3),which mainly includes two types: cytosolic LC3(LC3-?)and membrane LC3(LC3-II).When autophagy occurs,LC3-?undergoes an enzymatic hydrolysis reaction,which is decomposed into a LC3-?after degrading a peptide.Therefore,the detection of LC3-can estimate the level ?of autophagy to be more meaningful.The purpose of this study was to clarify the expression levels of STUB1,TFEB and LC3-in the renal tissues about ?idiopathic membranous nephropathy(IMN)and explore the relationship among their,and theirs regulation of autophagy.Methods: A total of 58 patients from the Third Hospital of Hebei Medical University with complete clinical data were collected from December 2018 to June 2019.Among them,52 patients who had the first Renal biopsy as Observation Group including 25 cases of IMN-?,There were 17 cases of IMN-and 10 cases of IMN?-(n1 = 25,n2 = 17,? n3 = 10).At the same time,the Control Group consisted of 6 cases of paracancerous tissue in patients undergoing nephrectomy in urology(n=6).Morphological Changes of renal tissues were observed by PASM and MASSON method.Using semi-quantitation method Immunohistochemical(IHC),we determined the expression levels of STUB1,TFEB and LC3-in paraffin sections of kidney ?tissues,and analyzed the relationship among the three indexes.Results: 1.General clinical data(Table 1): The sex ratios of the observation group and the control group are both about 1: 1.Compared with the observation group and the control group,there is a statistically significant difference in age and 24-hour urine protein(P<0.05).But each group was compared in pairs in the observation group.Comparison of each group in the observation group showed no statistically significant differences in age and quantitative 24-hour urine protein(P>0.05).2.Immunohistochemical staining(Fig.3-7,Table 2): STUB1 was mainly expressed in the mesangial cell nucleus and cytoplasm in the renal tissue of the Control Group and the Observation Group,and the expression of the Observation Group was stronger than that of the Control Group(P<0.001).TFEB was only scattered in renal tubular epithelial cells in the Control Group;however,it was expressed in the glomerular mesangial cells and renal tubular epithelial cells in the Observation Group,and it was mainly expressed in renal tubular epithelial cells.Compared with the Control Group,the expression of TFEB enhanced in the Observation Group(P<0.001).LC3-? was less expressed in the glomerular mesangial cells and renal tubular epithelial cells in the renal tissue of the Control Group,mainly expressed in the renal tubular epithelial cells;The expression of renal tubular epithelial cells enhanced in the Observation Group compared with the Control Group(P<0.001).The results of semi-quantitative analysis showed that compared with the Control Group,the expression of STUB1,TFEB and LC3-? were statistically different(P<0.001).The difference about the expression levels of the three factors compared pairwise in IMN-I,IMN-?and IMN-? were statistically(P<0.001).Between the Observation Group and the Control Group,STUB1 and TFEB,TFEB and LC3-?had Positive correlation.Conclusion: Autophagy participates in the development of adult IMN.And the possible mechanism is STUB1 ubiquitination protein TFEB is modified,which in turn regulates autophagy levels.