ABSTRACT
Acute kidney injury (AKI) is characterized by acute tubular necrosis (ATN) which involves mainly proximal tubules. Past AKI is associated with higher risk of chronic kidney disease (CKD). The MUC1 mucin is a large glycoprotein responsible for epithelial protection and locates to convoluted distal tubules and collecting ducts. Since MUC1 activates the epithelial-mesenchymal transition (EMT) in carcinoma cells, we hypothesized that MUC1 could be involved in epithelial tubular cell plasticity, a process that not only accompanies epithelial repair, but also participates into kidney fibrosis, histological substratum of CKD. In cultured human proximal cells and in human kidney allograft biopsies, we observed MUC1 induction in proximal tubules displaying ATN. Transient MUC1 induction localized with mesenchymal and stem-cell markers and was associated in vitro with reduced anoikis. In a mouse ischemia-reperfusion (IR) model, Muc1 expression mitigates severe tubular injury, as WT displayed less ATN than Muc1 KO mice. But, WT mice displayed more severe kidney fibrosis than Muc1 KO 28days after ischemia. Besides, sustained Muc1 expression in WT was associated with less kidney M2 macrophages. Human kidney biopsies performed within the first week (W1) of transplantation in the context of IR showed MUC1 W1 induction associated with EMT markers. Protocol biopsies performed 3months after demonstrated sustained abnormal MUC1 induction in atrophic tubules within kidney fibrosis. Altogether these data showed that sustained abnormal MUC1 induction accompanies failing epithelial repair, chronic inflammation and kidney fibrosis. In conclusion, MUC1 exerts opposite effects during kidney response to IR: first protective and then harmful.
Subject(s)
Kidney Diseases/metabolism , Kidney Tubules/metabolism , Mucin-1/metabolism , Reperfusion Injury/metabolism , Animals , Fibrosis , HEK293 Cells , Humans , Kidney Diseases/genetics , Kidney Diseases/pathology , Kidney Tubules/pathology , Mice , Mice, Knockout , Mucin-1/genetics , Reperfusion Injury/genetics , Reperfusion Injury/pathologyABSTRACT
The present study aimed at detecting the exogenously applied probiotic Lactobacillus farciminis in rats, after exposure to IBS-like chronic stress, based on 4-day Water Avoidance Stress (WAS). The presence of L. farciminis in both ileal and colonic mucosal tissues was demonstrated by FISH and qPCR, with ileum as the preferential niche, as for the SFB population. A different spatial distribution of the probiotic was observed: in the ileum, bacteria were organized in micro-colonies more or less close to the epithelium whereas, in the colon, they were mainly visualized far away from the epithelium. When rats were submitted to WAS, the L. farciminis population substantially decreased in both intestinal regions, due to a stress-induced increase in colonic motility and defecation, rather than a modification of bacterial binding to the intestinal mucin Muc2.
Subject(s)
Intestinal Mucosa/microbiology , Lactobacillus/pathogenicity , Stress, Psychological/microbiology , Animals , Colon/microbiology , Colon/ultrastructure , Ileum/microbiology , Ileum/ultrastructure , Intestinal Mucosa/ultrastructure , Male , Mucin-2/metabolism , Protein Binding , Rats , Rats, Wistar , Stress, Psychological/pathologyABSTRACT
MUC1 is a membrane-anchored mucin and its cytoplasmic tail (CT) can interact with many signaling pathways and act as a co-transcription factor to activate genes involved in tumor progression and metastasis. MUC1 is overexpressed in renal cell carcinoma with correlation to prognosis and has been implicated in the hypoxic pathway, the main renal carcinogenetic pathway. In this context, we assessed the effects of MUC1 overexpression on renal cancer cells properties. Using shRNA strategy and/or different MUC1 constructs, we found that MUC1-extracellular domain and MUC1-CT are involved in increase of migration, cell viability, resistance to anoikis and in decrease of cell aggregation in cancer cells. Invasiveness depends only on MUC1-CT. Then, by using siRNA strategy and/or pharmacological inhibitors or peptides, we showed that sheddases ADAM10, ADAM17 and gamma-secretase are necessary for MUC1 C-terminal subunit (MUC1-C) nuclear location and in increase of invasion property. Finally, MUC1 overexpression increases ADAM10/17 protein expression suggesting a positive regulatory loop. In conclusion, we report that MUC1 acts in renal cancer progression and MUC1-C nuclear localization drives invasiveness of cancer cells through a sheddase/gamma secretase dependent pathway. MUC1 appears as a therapeutic target by blocking MUC1 cleavage or nuclear translocation by using pharmacological approach and peptide strategies.
Subject(s)
Amyloid Precursor Protein Secretases/metabolism , Kidney Neoplasms/metabolism , Mucin-1/metabolism , Animals , Cell Line, Tumor , Cell Nucleus/metabolism , Disease Progression , Heterografts , Humans , Kidney Neoplasms/genetics , Kidney Neoplasms/pathology , Mice , Mice, SCID , Mucin-1/genetics , Protein Subunits , Signal Transduction , TransfectionABSTRACT
MUC1 is overexpressed in human carcinomas. The transcription factor SNAIL can activate epithelial-mesenchymal transition (EMT) in cancer cells. In this study, in renal carcinoma, we demonstrate that (i) MUC1 and SNAIL were overexpressed in human sarcomatoid carcinomas, (ii) SNAIL increased indirectly MUC1 expression, (iii) MUC1 overexpression induced EMT, (iv) MUC1 C-terminal domain (MUC1-C) and ß-catenin increased SNAIL transcriptional activity by interaction with its promoter and (v) blocking MUC1-C nuclear localization decreased Wnt/ß-catenin signaling pathway activation and SNAIL expression. Altogether, our findings demonstrate that MUC1 is an actor in EMT and appears as a new therapeutic target.
