Abstract: PO2012
Mitochondrial Quality Control Mechanisms in Renal Cortex During the Normoalbuminuric Stage of Diabetes Mellitus
Session Information
- Health Maintenance, Nutrition, and Metabolism: Basic
October 22, 2020 | Location: On-Demand
Abstract Time: 10:00 AM - 12:00 PM
Category: Health Maintenance, Nutrition, and Metabolism
- 1300 Health Maintenance, Nutrition, and Metabolism
Authors
- Ishii, Naohito, Kitasato University, Sagamihara, Japan
- Carmines, Pamela K., University of Nebraska Medical Center, Omaha, Nebraska, United States
- Kurosaki, Yoshifumi, Kitasato University, Sagamihara, Japan
- Imoto, Akemi, Kitasato University, Sagamihara, Japan
- Ikenaga, Hideki, Seiikai, Tochigi, Japan
- Yokoba, Masanori, Kitasato University, Sagamihara, Japan
- Ichikawa, Takafumi, Kitasato University, Sagamihara, Japan
- Takenaka, Tsuneo, International University of Health & Welfare, Minatoku, Japan
- Katagiri, Masato, Kitasato University, Sagamihara, Japan
Background
Oxidative stress during the normoalbuminuric stage of type 1 diabetes mellitus (DM) damages renal cortical mitochondria. Because accumulation of damaged mitochondria can contribute to renal dysfunction, we aimed to determine if oxidative stress in DM triggers 1) mitochondrial fission or fusion, 2) increased fatty acid metabolism, and/or 3) mitophagy as quality control mechanisms.
Methods
Rats receiving i.p. injection of streptozotocin (STZ, 65 mg/kg) or vehicle (Sham) were either left untreated or treated with telmisartan (TLM, an angiotensin receptor blocker; 10 mg/kg/d). Two weeks later, blood glucose levels (BG), blood pressure (BP), glomerular filtration rate, and urinary excretion of albumin and N-acetyl-β-D-glucosaminidase (NAG) were measured. The oxidative stress marker, 3-nitrotyrosine (3-NT), was detected by HPLC. Fission-, fusion-, and mitophagy-related proteins were quantified by Western blot. Levels of acylcarnitine, which transports fatty acids into mitochondria for β-oxidation, were calculated as the difference between total and free carnitine levels measured by the enzymatic cycling method using commercial kits.
Results
TZ rats displayed hyperglycemia and hyperfiltration that were unaffected by TLM. BP, albumin excretion, and NAG excretion were similar in all groups. Renal cortical 3-NT levels were increased in STZ rats, a change that was prevented by TLM (STZ+TLM). Renal cortical acylcarnitine levels in STZ rats were more than double those of Sham rats (P<0.05) and were further elevated in STZ+TLM rats (P<0.05 vs STZ alone). Renal cortex from STZ rats displayed TLM-sensitive increases in the mitophagy-related proteins LC3-II and PINK1 (all P<0.05). Renal cortical Drp1 levels were 3-fold higher in STZ than in Sham, with STZ+TLM rats exhibiting intermediate levels of this fission marker. Levels of the fusion marker Mfn2, and mitophagy-related proteins BNIP3 (dimer) and p62 did not differ among groups.
Conclusion
During the normoalbuminuric stage of DM, renal cortical mitochondria undergo increased fatty metabolism, as well as enhanced fission and mitophagy that are blunted by TLM in association with its antioxidant effect and, thus, are likely quality control mechanisms triggered by oxidative damage.