# Combined Multi-Omics Analysis Reveals the Potential Role of Methionine in Regulating the Proliferation, Differentiation, and Lipid Deposition of Yak Intramuscular Preadipocytes

## TL;DR

This study shows that methionine can boost fat deposition in yaks' muscle cells at moderate levels but causes stress at high levels, offering insights for improving meat quality.

## Contribution

The study is the first to demonstrate a biphasic effect of methionine on yak intramuscular preadipocytes and identifies the PI3K/AKT pathway as a key regulator.

## Key findings

- Moderate methionine (0.5 mM) promotes yak preadipocyte proliferation and differentiation, while excessive methionine (50 mM) suppresses these processes.
- Transcriptomic and proteomic analyses reveal that moderate methionine activates the ECM-receptor interaction and PI3K/AKT pathways.
- Excessive methionine induces DNA damage, oxidative stress, and metabolic dysregulation in yak preadipocytes.

## Abstract

Methionine (Met) is an essential amino acid that influences intramuscular fat (IMF) deposition, a key determinant of yak meat quality. However, the direct mechanism by which Met regulates yak intramuscular preadipocytes (YIMA) remains unknown. In this study, YIMA were exposed to a range of Met concentrations, and cellular assays combined with transcriptomic and proteomic profiling were used to dissect the dose-dependent effects. We found that moderate Met (0.5 mM) markedly promoted YIMA proliferation and adipogenic differentiation, whereas an excessive dose (50 mM) suppressed these processes. Transcriptomics and proteomics analysis revealed that moderate Met activated the ECM-receptor interaction and PI3K/AKT pathways, while excessive Met induced signatures of DNA damage, oxidative stress, and metabolic dysregulation. Functional validation confirmed that the PI3K/AKT pathway is essential for Met-driven adipogenesis and proliferation. This study provides the first yak-specific evidence of a biphasic Met effect and offers a mechanistic framework for optimizing dietary Met supplementation to improve intramuscular fat deposition without eliciting cellular stress.

This study employed integrated transcriptomics and proteomics analysis to investigate the potential role of methionine (Met) in regulating the proliferation, differentiation, and lipid deposition of yak intramuscular preadipocytes (YIMA). Five Met concentrations (0, 0.05, 0.5, 5, and 50 mM) were used to establish the Met model of YIMA. The results of Bodipy, Oil Red O, EdU staining, and qPCR showed that the appropriate Met (0.05, 0.5, and 5 mM) supplementation significantly promoted the proliferation and adipogenic differentiation of YIMA, whereas excessive Met (50 mM) markedly inhibited these processes. To further evaluate the mechanism of Met on YIMA, cells supplemented with 0 mM (control, CON), 0.5 mM (moderate) and 50 mM (excessive) Met were selected for the transcriptomic and proteomic analyses. The results showed that moderate Met treatment primarily enriched pathways related to extracellular matrix–receptor interaction and the PI3K/AKT signaling pathway, while excessive Met significantly enriched processes involving abnormal methylation, DNA damage, and metabolic stress. Functional validation experiments further confirmed that Met regulates YIMA proliferation and differentiation by upregulating p-Akt protein expression and activating the PI3K/AKT pathway. These findings provide molecular insights that support improving yak meat quality and IMF content through dietary Met supplementation.