title: Heme oxygenase-1 enhances autophagy in podocytes as a protective mechanism against high glucose-induced apoptosis.
abstract: Injury and loss of podocytes play vital roles in diabetic nephropathy progression. Emerging evidence suggests autophagy, which is induced by multiple stressors including hyperglycemia, plays a protective role. Meanwhile, heme oxygenase-1 (HO-1) possesses powerful anti-apoptotic properties. Therefore, we investigated the impact of autophagy on podocyte apoptosis under diabetic conditions and its association with HO-1. Mouse podocytes were cultured in vitro; apoptosis was detected by flow cytometry. Transmission electron microscopy and biochemical autophagic flux assays were used to measure the autophagy markers microtubule-associated protein 1 light chain 3-II (LC3-II) and beclin-1. LC3-II and beclin-1 expression peaked 12-24h after exposing podocytes to high glucose. Inhibition of autophagy with 3-methyladenine or Beclin-1 siRNAs or Atg 5 siRNAs sensitized cells to apoptosis, suggesting autophagy is a survival mechanism. HO-1 inactivation inhibited autophagy, which aggravated podocyte injury in vitro. Hemin-induced autophagy also protected podocytes from hyperglycemia in vitro and was abrogated by HO-1 siRNA. Adenosine monophosphate-activated protein kinase phosphorylation was higher in hemin-treated and lower in HO-1 siRNA-treated podocytes. Suppression of AMPK activity reversed HO-1-mediated Beclin-1 upregulation and autophagy, indicating HO-1-mediated autophagy is AMPK dependent. These findings suggest HO-1 induction and regulation of autophagy are potential therapeutic targets for diabetic nephropathy.
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Chenglong
authors.initials: C
authors.lastname: Dong
authors.affiliation: Department of Hyperbaric Oxygen, Nanjing General Hospital of Nanjing Military Command, Nanjing, China.
authors.forename: Haining
authors.initials: H
authors.lastname: Zheng
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Huang
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Na
authors.initials: N
authors.lastname: You
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Jiarong
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Ye
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Qun
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Yamin
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: You
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Heng
authors.initials: H
authors.lastname: Miao
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China. Electronic address: dingdafa2004@aliyun.com.
authors.forename: Dafa
authors.initials: D
authors.lastname: Ding
authors.affiliation: Department of Endocrinology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China. Electronic address: luyibing2004@126.com.
authors.forename: Yibing
authors.initials: Y
authors.lastname: Lu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D015153:Blotting, Western; D002478:Cells, Cultured; D005947:Glucose / Q000494:pharmacology*; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006427:Hemin; D051379:Mice; D050199:Podocytes / Q000187:drug effects / Q000201:enzymology / Q000473:pathology*; D020011:Protective Agents / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics
chemical_list: D020011:Protective Agents; D034741:RNA, Small Interfering; D006427:Hemin; D051547:Heme Oxygenase-1; D005947:Glucose
keywords: Apoptosis; Autophagy; Heme oxygenase-1; High glucose; Podocyte