Regulation of the Golgi apparatus via GOLPH3-mediated new selective autophagy.

AIMS: Although previous studies elaborated that selective autophagy was involved in quality control of some organelles, including nucleus, mitochondria, the endoplasmic reticulum and peroxisomes, it remained unclear whether the selective autophagy of the Golgi apparatus (Golgiphagy) existed or not. MAIN METHODS: In this study, H9c2 cells, HUVECs, HA-VSMCs and HEK293T cells were treated with autophagy inducers, Golgi stress inducers and cardiomyocytes hypertrophy stimulators. The Golgiphagy was evaluated by analysing the co-localization of Golgi markers and LC3B. Furthermore, the transmission electron microscope was used to observe the occurrence of Golgiphagy. The co-immunoprecipitation assay was used to evaluate the interaction of GOLPH3 and LC3B. KEY FINDINGS: Results showed that starvation promoted the co-localization of both GM130-positive and TGN46-positive Golgi fragments with LC3B-positive autophagosomes in H9c2 cells, HUVECs, HA-VSMCs and HEK293T cells. Transmission electron microscopy images showed that Golgi apparatus was sequestered into the autophagosomes in the starvation group. Moreover, Golgi stress inducers also facilitated the co-localization of Golgi markers and LC3B in H9c2 cells, HUVECs, HA-VSMCs and HEK293T cells. Furthermore, cardiomyocyte hypertrophy stimulators also triggered the appearance of Golgiphagy in H9c2 cells. Importantly, the co-immunoprecipitation assay indicated endogenous GOLPH3 interacted with LC3B in H9c2 cells, HUVECs, HA-VSMCs. However, knocking down GOLPH3 inhibited the Golgiphagy. SIGNIFICANCE: This study unveiled a new selective autophagy of the Golgi apparatus (Golgiphagy). In addition, GOLPH3 might act as a novel cargo receptor to regulate Golgiphagy. Maintaining homeostasis of the Golgi apparatus via GOLPH3-mediated autophagy was indispensable for cell survival.

The endoplasmic reticulum stress-autophagy pathway is involved in apelin-13-induced cardiomyocyte hypertrophy in vitro.

Apelin is the endogenous ligand for the G protein-coupled receptor APJ, and plays important roles in the cardiovascular system. Our previous studies showed that apelin-13 promotes the hypertrophy of H9c2 rat cardiomyocytes through the PI3K-autophagy pathway. The aim of this study was to explore what roles ER stress and autophagy played in apelin-13-induced hypertrophy of cardiomyocytes in vitro. Treatment of H9c2 cells with apelin-13 (0.001-2 µmol/L) dose-dependently increased the production of ROS and the expression levels of NADPH oxidase 4 (NOX4). Knockdown of Nox4 with siRNAs effectively prevented the reduction of GSH/GSSG ratio in apelin-13-treated cells. Furthermore, apelin-13 treatment dose-dependently increased the expression of Bip and CHOP, two ER stress markers, in the cells. Knockdown of APJ or Nox4 with the corresponding siRNAs, or application of NADPH inhibitor DPI blocked apelin-13-induced increases in Bip and CHOP expression. Moreover, apelin-13 treatment increased the formation of autophagosome and ER fragments and the LC3 puncta in the ER of the cells. Knockdown of APJ, Nox4, Bip or CHOP with the corresponding siRNAs, or application of DPI or salubrinal attenuated apelin-13-induced overexpression of LC3-II/I and beclin 1. Finally, knockdown of Nox4, Bip or CHOP with the corresponding siRNAs, or application of salubrinal significantly suppressed apelin-13-induced increases in the cell diameter, volume and protein contents. Our results demonstrate that ER stress-autophagy is involved in apelin-13-induced H9c2 cell hypertrophy.

[A pilot study of a novel method for bedside placement of post-pyloric feeding tubes in critically ill patients].

OBJECTIVE: To investigate a novel method of bedside placement of post-pyloric feeding tubes in critically ill patients, and to evaluate its success rate, time used, and safety of this bedside method. METHODS: Data of consecutive patients requiring post-pyloric feeding from February 2009 to July 2009 were collected. In this new method, a non weighted 130-cm-long nasoenteric feeding tube with a guide wire was used under 10 mg of intravenous metoclopramide. The tube was gradually advanced, and the position of the tube was confirmed by auscultation to detect bubbling sound and respiration of inflated air (the vacuum test), as well as pH measurement of aspirated fluid. An abdominal radiograph was made finally for confirmation of the position of the tube before the feeding was initiated. The time taken to insert the tube, the success rate, the time between the decision to feed and commencement of feeding, and the complications of the procedure were recorded. RESULTS: In 28 patients the post-pyloric feeding tube was placed. The main indication was 18 cases with high risk of aspiration, 3 with gastroparesis, and 7 with acute pancreatitis. Of the 28 tube placements performed, 26 (92.9%) were successful, and in 21 (75.0% of 28) the tube was in the jejunum. The average time for successful placement was (20.36+/-6.41) minutes. The time between the decision for feeding and commencement of feeding was (4.15+/-1.68) hours. No complications occurred. CONCLUSION: Using a conventional nasoenteric feeding tube with a guide wire, and only one medical staff needed for the placement of the tube, this method is an efficient and cost-effective method of bedside post-pyloric feeding tube placement.