# Rubimaillin ameliorates liver fibrosis by triggering the ferroptosis of activated hepatic stellate cells through targeting CPT1A

## TL;DR

Rubimaillin, a compound from traditional Chinese medicine, reduces liver fibrosis by causing cell death in liver cells through a process called ferroptosis.

## Contribution

Rubimaillin is shown to target CPT1A and induce ferroptosis in activated hepatic stellate cells, offering a new therapeutic strategy for liver fibrosis.

## Key findings

- Rubimaillin ameliorates liver fibrosis in mice by triggering ferroptosis in activated hepatic stellate cells.
- Rubimaillin directly binds to and inhibits CPT1A, leading to metabolic reprogramming and cell death.
- CPT1A deficiency or overexpression negates the effects of Rubimaillin-induced ferroptosis.

## Abstract

Liver fibrosis is defined as the excessive accumulation of extracellular matrix proteins in the liver due to chronic liver injury. Targeted ferroptosis of activated hepatic stellate cells (HSCs) is considered a promising therapeutic strategy for liver fibrosis. Rubimaillin (Rub), a naphthoquinone compound extracted from traditional Chinese medicine Rubia cordifolia L., exhibits various activities in multiple diseases. This study aimed to investigate the anti-hepatic fibrosis effect, the direct protein target, and molecular mechanism of Rub. Here, our results demonstrated that Rub effectively ameliorated liver fibrosis via triggering the ferroptosis of activated HSCs in mice models. Subsequently, we confirmed that Rub directly binds to carnitine palmitoyltransferase 1A (CPT1A) at SER592, THR594, and THR689, and inhibits its activity using PROTAC technology, computer molecular dynamics simulations, CETSA, DARTS, BLI, and site mutation assays. Further, the inhibition or deficiency of CPT1A in activated HSCs could trigger metabolic reprogramming-mediated ferroptosis. Moreover, CPT1A deficiency or overexpression could eliminate the effects of Rub-induced ferroptosis. Mechanistically, Rub-induced ferroptosis in activated HSCs was associated with metabolic reprogramming mediated by targeting CPT1A. Taken together, our results indicate the beneficial effects, the direct protein target and the molecular mechanism via which Rub induces ferroptosis in activated HSCs to ameliorate liver fibrosis.