Genetic ablation of p62/SQSTM1 demonstrates little effect on pancreatic ß-cell function under autophagy deficiency.

Autophagy is known to play an essential role in intracellular quality control through the degradation of damaged organelles and components. We previously demonstrated that ß-cell-specific autophagy deficient mice, which lack Atg7, exhibited impaired glucose tolerance, accompanied by the accumulation of sequestosome 1/p62 (hereafter referred to as p62). Whereas p62 has been reported to play essential roles in regulating cellular homeostasis in the liver and adipose tissue, we previously showed that ß-cell-specific p62 deficiency does not cause any apparent impairment in glucose metabolism. In the present study, we investigated the roles of p62 in ß cells under autophagy-deficient conditions, by simultaneously inactivating both Atg7 and p62 in a ß-cell specific manner. Whereas p62 accumulation was substantially reduced in the islets of Atg7 and p62 double-deficient mice, glucose tolerance and insulin secretion were comparable to Atg7 single-deficient mice. Taken together, these findings suggest that the p62 accumulation appears to have little effect on ß-cell function under conditions of autophagy inhibition.

In-Depth Insight Into the Mechanisms of Cardiac Dysfunction in Patients With Type 1 Diabetes Mellitus Using Layer-Specific Strain Analysis.

BACKGROUND: Although the subclinical left ventricular (LV) dysfunction caused by diabetes mellitus (DM) results in a high risk of death and heart failure, the details of cardiac dysfunction across a wide age range remain unclear. The aim of this study was to assess LV dysfunction in patients with type 1 DM (T1DM) using layer-specific strain analysis by echocardiography.Methods and Results:The 52 patients (median age: 23 [range: 5-40] years) with T1DM were divided into 3 age groups (D1: 5-14 years, D2: 15-24 years, D3: 25-40 years); 78 age- and sex-similar controls were divided into 3 corresponding groups (C1, C2, and C3). Layer-specific longitudinal strain (LS) and circumferential strain (CS) of the 3 myocardial layers (endocardium, midmyocardium, and epicardium) were determined using echocardiography. Strains did not decrease in D1. Epicardial and midmyocardial CS at the basal level and LS in all layers were decreased in D2 compared with C2. CS at the basal level and LS in all layers were lower in D3 than in C3. The strains correlated with the duration of T1DM and LV wall thickness. CONCLUSIONS: In patients with T1DM, longitudinal deformation in all layers and epicardial and midmyocardial circumferential deformation at the basal level decreased from the late teens, which correlated with the duration of the disease and LV hypertrophy.