Comparative Morphological and Proteomic Characterization of Adipose Tissues from Different Anatomical Sites in Yili Horses.

Overview

• This study compared the structural and protein composition differences between subcutaneous and pericardial fat tissues in Yili horses.
• It identified unique characteristics and proteins linked to the specific functions and metabolism of fat from these two regions.

Background

• Adipose tissue is not only a storage site for energy but also acts as an endocrine organ, influencing metabolic processes.
• Different adipose depots (fat tissues located in various parts of the body) may have distinct morphological and molecular characteristics, which can affect their function.
• Yili horses, a specific breed, were studied to understand these differences, particularly between subcutaneous adipose tissue (SAT) and pericardial adipose tissue (PCAT).

Research Objectives

• To compare the morphology (cell size and number) of SAT and PCAT in Yili horses.
• To identify differences in protein expression profiles between these two types of adipose tissue.
• To map the biological pathways these proteins participate in and connect morphological differences to specific proteins.

Methodology

• Sample Collection:
  • Adipose tissue samples were taken from 18 Yili horses for morphological analysis.
  • A subgroup of 6 horses’ samples was selected for proteomic profiling.
• Histology:
  • Hematoxylin and eosin (H&E) staining was used to study the tissue morphology under a microscope.
  • Measurements included adipocyte (fat cell) area, diameter, and the number of cells per microscopic field.
• Proteomic Analysis:
  • Mass spectrometry or related techniques identified differentially expressed proteins (DEPs) between SAT and PCAT.
  • Bioinformatics tools performed Gene Ontology (GO) and KEGG pathway enrichment analyses to understand protein functions and related biological pathways.
• Correlation Analysis:
  • Statistical methods linked specific protein expression levels to the measured morphological traits of adipocytes.

Key Findings

• Morphological Differences:
  • Adipocytes in PCAT were larger in size (both area and diameter) than those in SAT.
  • PCAT showed fewer adipocytes per microscopic field compared to SAT.
• Proteomic Differences:
  • 451 proteins were differentially expressed between SAT and PCAT.
  • DEPs were enriched in pathways related to fat metabolism (fatty acid catabolism, glycolysis), structural tissue interaction (ECM-receptor interaction), thermogenesis, and signaling pathways such as Wnt.
• Functional Implications:
  • SAT showed greater activity in substrate utilization, energy metabolism, and lipid turnover, suggesting it is more metabolically active.
  • PCAT was linked more with structural and cardiovascular-related signaling, indicating a role beyond energy storage, possibly in heart and vessel support.
• Candidate Regulatory Proteins:
  • Proteins correlated with morphological differences include:
    • ACAA2 (Acetyl-Coenzyme A Acyltransferase 2) – involved in fatty acid metabolism
    • ENO1 (Enolase 1) and TPI1 (Triosephosphate isomerase 1) – glycolytic enzymes
    • PLIN1 (Perilipin 1) – key in lipid droplet regulation
    • COL6A3 (Collagen type VI alpha 3 chain) and ITGB1 (Integrin beta-1) – involved in extracellular matrix and cell adhesion

Conclusions and Significance

• The study demonstrated clear anatomical site-specific differences in adipose tissue morphology and protein composition in Yili horses.
• Such differences provide insights into the specialized roles of fat depots — SAT being more metabolically dynamic and PCAT potentially playing structural and cardiovascular roles.
• Identification of key proteins offers potential targets for further research on adipose tissue regulation, metabolic function, and possibly equine health related to fat distribution.
• This foundational knowledge can aid in understanding adipose tissue diversity in horses and may inform breeding, health management, and disease prevention strategies.