Objective:

2

To investigate the effect of emodin on high glucose (HG)-induced podocyte apoptosis and whether the potential anti-apoptotic mechanism of emodin is related to induction of adenosine-monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR)-mediated autophagy in podocytes (MPC5 cells)

in vitro

.

Methods:

2

MPC5 cells were treated with different concentrations of HG (2.5

5

10

20

40

80 and 160 mmol/L)

emodin (2

4

8 μmol/L)

or HG (40 mmol/L) and emodin (4 μmol/L) with or without rapamycin (Rap

100 nmol/L) and compound C (10 μmol/L). The viability and apoptosis of MPC5 cells were detected using cell counting kit-8 (CCK-8) assay and flow cytometry analysis

respectively. The expression levels of cleaved caspase-3

autophagy marker light chain 3 (LC3) Ⅰ/Ⅱ

and AMPK/mTOR signaling pathway-related proteins were determined by Western blot. The changes of morphology and RFP-LC3 fluorescence were observed under microscopy.

Results:

2

HG at 20

40

80 and 160 mmol/L dose-dependently induced cell apoptosis in MPC5 cells

whereas emodin (4 μmol/L) significantly ameliorated HG-induced cell apoptosis and caspase-3 cleavage (

P

<

0.01). Emodin (4 μmol/L) significantly increased LC3-Ⅱ protein expression levels and induced RFP-LC3-containing punctate structures in MPC5 cells (

P

<

0.01). Furthermore

the protective effects of emodin were mimicked by rapamycin (100 nmol/L). Moreover

emodin increased the phosphorylation of AMPK and suppressed the phosphorylation of mTOR. The AMPK inhibitor compound C (10 μmol/L) reversed emodin-induced autophagy activation.

Conclusion:

2

Emodin ameliorated HG-induced apoptosis of MPC5 cells

in vitro

that involved induction of autophagy through the AMPK/mTOR signaling pathway

which might provide a potential therapeutic option for diabetic nephropathy.