# Differential Analysis of Fecal SCFAs and Their Contribution to Adipogenesis in UCP1 Knock-In Pigs

## TL;DR

This study explores how changes in gut microbiota and short-chain fatty acids (SCFAs) in UCP1 gene-edited pigs affect fat development.

## Contribution

The study identifies a link between reduced Streptococcus spp. and lower SCFA levels in UCP1 knock-in pigs, impacting adipogenesis.

## Key findings

- Caproic acid significantly enhances adipocyte differentiation by activating the FFAR4 gene in vitro.
- Streptococcus spp. abundance is positively correlated with SCFA levels and pig body weight.
- Fecal SCFA concentrations are significantly lower in UCP1 knock-in pigs compared to wild-type pigs.

## Abstract

Short-chain fatty acids (SCFAs) are the primary metabolites produced by the gut microbiota from the fermentation of dietary fibre. They frequently function as a kind of signal molecule, regulating the expression of genes within the host cell. The results of animal studies indicate that SCFAs are involved in the acquisition of energy and may contribute to the development of obesity. In this study, we utilized targeted metabolomics and 16s rRNA sequencing techniques to pinpoint gut microbial communities potentially implicated in short-chain fatty acid metabolism. The identified short-chain fatty acids were then applied in in vitro adipocyte validation and lipogenic function studies. These efforts aim to offer a scientific foundation for the commercialization of UCP1 gene-edited pigs.

This study aimed to investigate the changes in fecal short-chain fatty acids (SCFAs) content in UCP1 knock-in pigs (KI pigs) and their effect on adipogenesis. Fecal samples from five 6-month-old wild-type (WT) and KI pigs were collected for targeted metabolomics and 16s rRNA sequencing analyses to identify differences in SCFAs and gut microbiota that may contribute to regulating fat deposition in pigs. The metabolome of pig fecal samples targeted for an analysis of SCFAs identified seven SCFAs, with caproic acid (except isovaleric acid) being the significantly different one. The results of the fecal 16s rRNA analysis demonstrated a notable reduction in the abundance of Streptococcus spp. in the KI pigs in comparison to the WT pigs, with a statistically significant difference. Correlation analyses demonstrated a statistically significant positive correlation between the abundance of Streptococcus spp. and SCFAs, as well as pig body weight and fatness. It was postulated that the reduction in SCFAs in the intestinal tracts of KI pigs may be associated with a reduction in Streptococcus spp. abundance. Compared to WT pigs, the concentration of fecal SCFAs in KI pigs was significantly reduced, which may be related to the decreased abundance of Streptococcus. The in vitro experiments showed that caproic acid could significantly enhance the differentiation efficiency of porcine SVF cells into mature adipocytes by activating the FFAR4 gene.