Trehalose, an mTOR Independent Autophagy Inducer, Alleviates Human Podocyte Injury after Puromycin Aminonucleoside Treatment

Abstract

Glomerular diseases are commonly characterized by podocyte injury including apoptosis, actin cytoskeleton rearrangement and detachment. However, the strategies for preventing podocyte damage remain insufficient. Recently autophagy has been regarded as a vital cytoprotective mechanism for keeping podocyte homeostasis. Thus, it is reasonable to utilize this mechanism to attenuate podocyte injury. Trehalose, a natural disaccharide, is an mTOR independent autophagy inducer. It is unclear whether trehalose alleviates podocyte injury. Therefore, we investigated the efficacy of trehalose in puromycin aminonucleoside (PAN)-treated podocytes which mimic cell damage in minimal change nephrotic syndrome in vitro. Human conditional immortalized podocytes were treated with trehalose with or without PAN. Autophagy was investigated by immunofluorescence staining for LC3 puncta and Western blotting for LC3, Atg5, p-AMPK, p-mTOR and its substrates. Podocyte apoptosis and necrosis were evaluated by flow cytometry and by measuring lactate dehydrogenase activity respectively. We also performed migration assay to examine podocyte recovery. It was shown that trehalose induced podocyte autophagy in an mTOR independent manner and without reactive oxygen species involvement. Podocyte apoptosis significantly decreased after trehalose treatment, while the inhibition of trehalose-induced autophagy abolished its protective effect. Additionally, the disrupted actin cytoskeleton of podocytes was partially reversed by trehalose, accompanying with less lamellipodias and diminished motility. These results suggested that trehalose induced autophagy in human podocytes and showed cytoprotective effects in PAN-treated podocytes.

SLC2A8 (GLUT8) is a mammalian trehalose transporter required for trehalose-induced autophagy

“…5 and ref. 19), yet mTORC inhibition was insufficient to induce autophagic flux in HepG2 hepatocytes and in primary hepatocytes in concordance with prior reports34675051. Trehalose-induced autophagy may be cell-type specific with respect to mTORC1 blockade.…”

“…Trehalose is a disaccharide previously demonstrated to induce autophagy and mitigate multiple disease models through incompletely defined mechanisms3456789. This body of work established trehalose as an attractive nutraceutical to interrogate mechanistically, and indeed, the prospect that trehalose – or a ‘designer drug’ based upon the trehalose mechanism of action – will translate into a bona fide human therapeutic for metabolic disease is gaining traction10.…”

Autophagy in kidney disease and aging: lessons from rodent models

“…Autophagy was also found to have protective properties in puromycin-aminonucleoside-treated human podocytes. 151 A decreased number of autophagic vacuoles was described in podocytes from patients with FSGS. 149 Finally, pharmacological induction of autophagy delays the progression of FSGS.…”

The roles of oxidative stress, endoplasmic reticulum stress, and autophagy in aldosterone/mineralocorticoid receptor-induced podocyte injury

“…Moreover, autophagy inducers can reduce podocyte injury by increasing autophagy levels. 25,26 The mammalian target of Rapa (mTOR) is a negative regulator of autophagy. Autophagy can be induced in an mTOR-dependent or -independent manner by diverse input signals.…”