Endoplasmic Reticulum Homeostasis and Stress Responses in Caenorhabditis elegans

The Intestine as a Lifespan- and Proteostasis-Promoting Signaling Tissue

In multicellular organisms such as Caenorhabditis elegans, cellular stress stimuli and responses are communicated between tissues to promote organismal health- and lifespan. The nervous system is the predominant regulator of cell nonautonomous proteostasis that orchestrates systemic stress responses to integrate both internal and external stimuli. This review highlights the role of the intestine in mediating cell nonautonomous stress responses and explores recent findings that suggest a central role for the intestine to regulate organismal proteostasis. As a tissue that receives and further transduces signals from the nervous system in response to dietary restriction, heat- and oxidative stress, and hypoxia, we explore evidence suggesting the intestine is a key regulatory organ itself. From the perspective of naturally occurring stressors such as dietary restriction and pathogen infection we highlight how the intestine can function as a key regulator of organismal proteostasis by integrating insulin/IGF-like signaling, miRNA-, neuropeptide- and metabolic signaling to alter distal tissue functions in promoting survival, health- and lifespan.

Melatonin reduces the endoplasmic reticulum stress and polyubiquitinated protein accumulation induced by repeated anesthesia exposure in Caenorhabditis elegans

Endoplasmic reticulum (ER) stress has been linked to anesthesia-induced neurotoxicity, but melatonin seems to play a protective role against ER stress. Synchronized Caenorhabditis elegans were exposed to isoflurane during the developmental period; melatonin treatment was used to evaluate its role in preventing the defective unfolded protein response (UPR) and ER-associated protein degradation (ERAD). The induced expression of hsp-4::GFP by isoflurane was attenuated in the isoflurane-melatonin group. Isoflurane upregulated the expression of ire-1, whereas melatonin did not induce ire-1 expression in C. elegans even after isoflurane exposure. With luzindole treatment, the effect of melatonin on the level of ire-1 was significantly attenuated. The reduced expression of sel-1, sel-11, cdc-48.1, and cdc-48.2 due to isoflurane was restored by melatonin, although not up to the level of the control group. The amount of polyubiquitinated proteins was increased in the isoflurane group; however, melatonin suppressed its accumulation, which was significantly inhibited by a proteasome inhibitor, MG132. The chemotaxis index of the isoflurane-melatonin group was improved compared with the isoflurane group. Melatonin may be a potential preventive molecule against defective UPR and ERAD caused by repeated anesthesia exposure. The ire-1 branch of the UPR and ERAD pathways can be the target of melatonin to reduce anesthesia-induced ER stress.

The Effects of Bergamot Polyphenolic Fraction, Cynara cardunculus, and Olea europea L. Extract on Doxorubicin-Induced Cardiotoxicity

Doxorubicin is an anthracycline that is commonly used as a chemotherapy drug due to its cytotoxic effects. The clinical use of doxorubicin is limited due to its known cardiotoxic effects. Treatment with anthracyclines causes heart failure in 15–17% of patients, resulting in mitochondrial dysfunction, the accumulation of reactive oxygen species, intracellular calcium dysregulation, the deterioration of the cardiomyocyte structure, and apoptotic cell death. Polyphenols have a wide range of beneficial properties, and particular importance is given to Bergamot Polyphenolic Fraction; Oleuropein, one of the main polyphenolic compounds of olive oil; and Cynara cardunculus extract. These natural compounds have particular beneficial characteristics, owing to their high polyphenol contents. Among these, their antioxidant and antoproliferative properties are the most important. The aim of this paper was to investigate the effects of these three plant derivatives using an in vitro model of cardiotoxicity induced by the treatment of rat embryonic cardiomyoblasts (H9c2) with doxorubicin. The biological mechanisms involved and the crosstalk existing between the mitochondria and the endoplasmic reticulum were examined. Bergamot Polyphenolic Fraction, Oleuropein, and Cynara cardunculus extract were able to decrease the damage induced by exposure to doxorubicin. In particular, these natural compounds were found to reduce cell mortality and oxidative damage, increase the lipid content, and decrease the concentration of calcium ions that escaped from the endoplasmic reticulum. In addition, the direct involvement of this cellular organelle was demonstrated by silencing the ATF6 arm of the Unfolded Protein Response, which was activated after treatment with doxorubicin.