Autocrine Exosomal Fibulin-1 as a Target of MiR-1269b Induces Epithelial-Mesenchymal Transition in Proximal Tubule in Diabetic Nephropathy

Yi-Chun Tsai; Wei-Wen Hung; Wei-An Chang; Ping-Hsun Wu; Ling-Yu Wu; Su-Chu Lee; Mei-Chuan Kuo; Ya-Ling Hsu

doi:10.3389/fcell.2021.789716

Autocrine Exosomal Fibulin-1 as a Target of MiR-1269b Induces Epithelial-Mesenchymal Transition in Proximal Tubule in Diabetic Nephropathy

Front Cell Dev Biol. 2021 Dec 17:9:789716. doi: 10.3389/fcell.2021.789716. eCollection 2021.

Authors

Yi-Chun Tsai^{1

2

3

4

5}, Wei-Wen Hung⁶, Wei-An Chang⁷, Ping-Hsun Wu^{1

3}, Ling-Yu Wu⁸, Su-Chu Lee³, Mei-Chuan Kuo³, Ya-Ling Hsu^{4

9}

Affiliations

¹ School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
² Division of General Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
³ Division of Nephrology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
⁴ Drug Development and Value Creation Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan.
⁵ Center for Liquid Biopsy and Cohort Research, Kaohsiung Medical University, Kaohsiung, Taiwan.
⁶ Division of Endocrinology and Metabolism, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
⁷ Division of Pulmonary and Critical Care Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
⁸ College of Medicine, Graduate Institute of Clinical Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
⁹ College of Medicine, Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.

Abstract

Background: Diabetic nephropathy (DN) is an increasing threat to human health and is regarded to be the leading cause of end-stage renal disease worldwide. Exosomes deliver biomolecule massages and may play a key role in cell communication and the progression of DN. Methods: A cross-disciplinary study, including in vivo, in vitro, and human studies, was conducted to explore the cross-talk within proximal tubular epithelial cells (PTECs) in DN. Exosomal protein from PTECs treated with high glucose (HG) was purified and examined using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Next-generation sequencing (NGS) was utilized to analyze RNAs extracted from PTECs from a type 2 diabetic patient and a normal individual. HK-2 cells were used to assess exosomal protein and its modulation and biofunction in DN. Normal individuals and type 2 diabetic patients were enrolled, and nondiabetic db/m mice and diabetic db/db mice were used to validate the molecular mechanism of exosomes in DN. Results: HG stimulated PTECs to increase Fibulin-1 (FBLN1) expression, and PTECs secreted FBLN1 through exosome delivery, thereby inducing epithelial-mesenchymal transition (EMT) in PTECs. Transcriptome analysis found that FBLN1 expression was modulated by miR-1269b, which was downregulated by HG in HK-2 cells. While transfection of miR-1269b reversed FBLN1-mediated EMT in PTECs, miR-1269b inhibitor modulated the phenotype of PTECs toward mesenchymal type under normal glucose (NG) condition. Most importantly, urinary FBLN1 and exosomal miR-1269b levels were correlated with the severity of kidney injury in type 2 diabetic patients. Conclusion: This study demonstrated the communication within PTECs through exosome transmission in an autocrine pattern. MiR-1269b-FBLN1 epigenetic regulatory network could be a potential therapeutic strategy to prevent the progression of DN.

Keywords: FBLN1; diabetic nephropathy; epithelial–mesenchymal transition; exosome; miR-1269b; proximal tubule.