# Porcine SCD1 Regulates Lipid Droplet Number via CLSTN3B in PK15 Cells

## TL;DR

This study shows that SCD1 in pig cells controls lipid droplet numbers through CLSTN3B, affecting fat storage and meat quality.

## Contribution

The novel finding is that SCD1 regulates lipid droplet number via CLSTN3B in porcine cells.

## Key findings

- SCD1 deletion reduced triacylglycerols and lipid droplet numbers in PK15 cells.
- SCD1 overexpression increased lipid droplet numbers, confirming its regulatory role.
- RNA-seq identified CLSTN3B as a key mediator of SCD1's effect on lipid droplets.

## Abstract

Fat deposition is a critical determinant of pork quality traits, with lipid droplets serving as essential organelles for lipid storage in adipose tissue. However, the role of SCD1 in lipid droplet biogenesis remains unclear. In this study, we utilized CRISPR/Cas9 to generate SCD1-deficient cells and found that SCD1 regulates both fatty acid composition and lipid droplet number. RNA-seq analysis further revealed an association between SCD1 and CLSTN3B, and experimental validation demonstrated that SCD1 modulates lipid droplet number via targeting CLSTN3B.

Fat deposition plays a key role in determining porcine meat quality traits, with lipid droplets serving as critical organelles for lipid storage in adipose tissue. Inhibiting lipid droplet biogenesis disrupts the lipid storage capacity of adipocytes. The Stearoyl-CoA Desaturase (SCD) family is crucial in regulating polyunsaturated fatty acid/monounsaturated fatty acid (PUFA/MUFA) composition, while its role in lipid droplet formation remains unclear. This study employed CRISPR/Cas9 to create SCD1-deficient porcine renal epithelial cells (PK15), enabling an investigation into SCD1’s role in fatty acid composition and lipid droplet regulation. RNA-seq analysis was conducted to elucidate the mechanisms underlying SCD1’s impact on lipid droplet numbers. Results showed that SCD1 deletion significantly decreased triacylglycerols (TAG) content, altered fatty acid composition, and decreased lipid droplet numbers. Conversely, SCD1 overexpression increased lipid droplet numbers, confirming SCD1’s role in regulating lipid droplet abundance. RNA-seq analysis revealed that SCD1 regulates lipid metabolism via Calsyntenin 3β (CLSTN3B). Experimental validation confirmed the SCD1-CLSTN3B regulation of lipid droplet numbers. In summary, we discovered the role of SCD1 in regulating the number of lipid droplets, highlighting its potential impact on lipid metabolism and adipocyte function in pigs.