# CTRP13-Mediated Effects on Endothelial Cell Function and Their Potential Role in Obesity

## TL;DR

This study shows that CTRP13, a protein linked to obesity, affects endothelial cell function and may contribute to vascular disease.

## Contribution

The study reveals that CTRP13 is upregulated in endothelial cells during obesity and has vaso-modulatory effects.

## Key findings

- CTRP13 is expressed in endothelial cells and is elevated in obese individuals.
- CTRP13 reduces endothelial cell proliferation and alters cell cycle progression via AMPK.
- High glucose and TNF-alpha increase CTRP13 expression in endothelial cells.

## Abstract

Background: Obesity, a major component of cardiometabolic syndrome, contributes to the imbalance between pro- and anti-atherosclerotic factors via dysregulation of adipocytokine secretion. Among these adipocytokines, the C1q/TNF-related proteins (CTRPs) play a role in the modulation of atherosclerosis development and progression. Here, we investigated the vascular effects of CTRP13. Results: CTRP13 is not only expressed in adipose tissue but also in vessels/endothelial cells (ECs) of mice, rats, and humans. Obese individuals (mice, rats, and humans) showed higher vascular CTRP13 expression. Human Umbilical Vein Endothelial Cells (HUVECs), cultured in the presence of serum from obese mice, mimicked this obesity-associated effect on CTRP13 protein expression. Similarly, high glucose conditions and TNF-alpha, but not insulin, resulted in a strong increase in CTRP13 in these cells. Recombinant CTRP13 induced a reduction in EC proliferation via AMPK. In addition, CTRP13 reduced cell cycle progression and increased p53 phosphorylation and p21 protein expression, but reduced Rb phosphorylation, with the effects largely depending on alpha-2 AMPK as suggested by adenoviral overexpression of dominant-negative (DN) or wild-type (WT) alpha 1/alpha 2 AMPK. Conclusion: The present study demonstrates that CTRP13 expression is induced in ECs under diabetic conditions and that CTRP13 possesses significant vaso-modulatory properties which may have an impact on vascular disease progression in patients.