Short-term exposure to an obesogenic diet causes dynamic dysregulation of proteasome-mediated protein degradation in the hypothalamus of female rats

ABSTRACT

Objectives

Previous work has shown that exposure to a high fat diet dysregulates the protein degradation process in the hypothalamus of male rodents. However, whether this occurs in a sex-independent manner is unknown. The objective of this study was to determine the effects of a short-term obesogenic diet on the ubiquitin-proteasome mediated protein degradation process in the hypothalamus of female rats.

Methods

We fed young adult female rats a high fat diet or standard rat chow for 7 weeks. At the end of the 7th week, animals were euthanized and hypothalamus nuclear and cytoplasmic fractions were collected. Proteasome activity and degradation-specific (K48) ubiquitin signaling were assessed. Additionally, we transfected female rats with CRISPR-dCas9-VP64 plasmids in the hypothalamus prior to exposure to the high fat diet in order to increase proteasome activity and determine the role of reduced proteasome function on weight gain from the obesogenic diet.

Results

We found that across the diet period, females gained weight significantly faster on the high fat diet than controls and showed dynamic downregulation of proteasome activity, decreases in proteasome subunit expression and an accumulation of degradation-specific K48 polyubiquitinated proteins in the hypothalamus. Notably, while our CRISPR-dCas9 manipulation was able to selectively increase some forms of proteasome activity, it was unable to prevent diet-induced proteasome downregulation or abnormal weight gain.

Conclusions

Collectively, these results reveal that acute exposure to an obesogenic diet causes reductions in the protein degradation process in the hypothalamus of females.

KEYWORDS:

• Obesity
• sex differences
• hypothalamus
• ubiquitin
• proteasome

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data presented here are included within the manuscript text. Individual requests for data files can be sent to the corresponding author.

Additional information

Funding

This work was supported by National Institute of Health (NIH) [grant numbers MH120498, MH120569, MH122414 and MH123742] and U.S. Department of Agriculture (USDA) HATCH fund [project number VA-160114]. T.M. is supported by a Diversity Supplement from the National Institute of Mental Health (NIMH) and the George Washington Carver Program at Virginia Tech.