A potential application of the MP matrix is indicated to reduce dietary lipid absorption by promoting bile acid binding and regulating intestinal and hepatic lipid-related gene expression.
Abstract
Dietary lipids are typically ingested within complex protein-lipid matrices, where the protein source serves as a primary determinant of lipid digestion and bioavailability. However, the role of myofibrillar proteins, which are major components of meat, in influencing lipid handling and systemic lipid metabolism remains unclear. In this study, we examined the effects of four dietary protein matrices, i.e., myofibrillar protein (MP), sarcoplasmic protein (SP), casein (CAS), and soy protein isolate (SPI) on lipid bioavailability and enterohepatic metabolism in adolescent female C57BL/6J mice. Adolescent female C57BL/6J mice received daily oral gavage of 0.2 mL protein-lipid matrices consisting of soybean oil and protein solution (1 : 1, v/v; 10 mg mL-1 protein) for 32 days. The MP-Oil group exhibited significantly higher fecal excretion of lipids and bile acids, alongside reduced serum total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels compared to the other protein groups. The MP-Oil treatment was also associated with downregulation of intestinal genes involved in lipid uptake (Cd36, Fabp2), re-esterification (Mogat2, Dgat1), and chylomicron assembly (Mttp). In addition, Asbt, Ostα, Fxr, and Fgf15 were downregulated in the ileum but upregulated Cyp7a1 in the liver. These findings indicate a potential application of the MP matrix to reduce dietary lipid absorption by promoting bile acid binding and regulating intestinal and hepatic lipid-related gene expression.
Elevated circulating nonesterified fatty acids (NEFA) represent a key pathological feature in dairy cows with fatty liver. Palmitic acid (PA), a major component of NEFA, can be enzymatically attached to proteins via a reversible post-translational modification known as palmitoylation, which potently modulates protein activity and function. Studies have revealed that aberrant hepatic palmitoylation is a crucial mechanism promoting lipid accumulation in non-ruminants. Nevertheless, the extent and pathological relevance of hepatic protein palmitoylation in dairy cows with fatty liver have largely remained unexplored. Therefore, this study was conducted to determine the status of hepatic protein palmitoylation in dairy cows with fatty liver and to elucidate its functional role in the development of hepatic steatosis. Blood and liver samples were collected from 10 dairy cows with fatty liver (hepatic triglyceride [TG] content >5%) and 10 control cows (hepatic TG content <1%) that had a similar number of lactations (median: 3, range: 2 to 4) and days in milk (median: 9 d, range: 5 to 14 d). To determine the effects of NEFA on palmitoylation, hepatocytes isolated from calves were treated with 1.2 mM NEFA for 12 h. To investigate the effects of palmitoylation on lipid accumulation in bovine hepatocytes, the cells were treated with 1.2 mM NEFA for 12 h in the presence or absence of a palmitoylation inhibitor (2-bromohexadecanoic acid). The results revealed that dairy cows with fatty liver exhibited liver injury and elevated hepatic palmitoyl-CoA content. Moreover, fatty liver dairy cows showed higher hepatic mRNA abundance of ZDHHC4/5/14/20 and lower mRNA abundance of ZDHHC3/19/21/23/24. In contrast, the mRNA abundance of depalmitoylase-related genes, including lysophospholipase 1 (LYPLA1 and LYPLA2), palmitoyl-protein thioesterase 1 (PPT1 and PPT2) and abhydrolase domain containing 17 (ABHD17A, ABHD17B and ABHD17C), was lower in the liver of cows with fatty liver than in control cows. Consistently, a greater abundance of palmitoylated proteins was observed in the liver of dairy cows with fatty liver. In vitro, NEFA treatment induced lipid accumulation, cell injury, and aberrant protein palmitoylation in bovine hepatocytes. Additionally, the upregulation of palmitoyltransferases and downregulation of depalmitoylases observed in cows with fatty liver were recapitulated in NEFA-treated bovine hepatocytes. Importantly, pharmacological inhibition of palmitoylation significantly alleviated NEFA-induced lipid accumulation and cell damage in bovine hepatocytes. Overall, these findings establish protein palmitoylation as both a critical pathological mechanism and a promising therapeutic target for fatty liver in dairy cows.
Yan Tian, Xiaobing Li, Shiyue Ma et al.· Journal of Dairy Science· 0 citations
Protein utilization efficiency is a key determinant of metabolic health, body composition, and muscle function, particularly under high-protein dietary conditions and when using plant-based protein sources with lower digestibility. However, the extent to which enhancing early gastric proteolysis translates into improved whole-body protein utilization remains unclear. The present in vivo study investigated whether supplementation with an actinidin-enriched kiwifruit concentrate (Kwd+®) modulates protein utilization efficiency and physiological outcomes under normoproteic and hyperproteic dietary conditions using casein or pea protein as dietary sources. Rats were fed normoproteic casein (NP), high-protein casein (CHP), or high-protein pea (PHP) diets with or without Kwd+® supplementation for 8 weeks. Gastric protein hydrolysis patterns were evaluated by SDS–PAGE, while metabolic outcomes were assessed through body composition, plasma amino acid profiling, skeletal muscle morphology, and contractile function. Kwd+® supplementation enhanced gastric proteolysis in a protein source-dependent manner. Despite the absence of significant changes in circulating amino acid concentrations after multiple comparison correction, Kwd+® improved markers of protein utilization efficiency depending on dietary protein source. In animals fed a high-protein pea diet, supplementation significantly reduced fat mass relative to accumulated protein intake, indicating improved nutrient partitioning. In contrast, in animals fed a high-protein casein diet, Kwd+® increased muscle mass relative to protein intake, suggesting enhanced anabolic efficiency. Under normoproteic conditions, Kwd+® supplementation was associated with an increased muscle fiber cross-sectional area and improved fatigue resistance without alterations in fiber type composition or contractile protein abundance. These findings demonstrate that modulation of early gastric proteolysis through actinidin produces protein source-dependent effects on protein utilization efficiency, nutrient partitioning, and muscle function. This work highlights a novel nutritional strategy to improve metabolic outcomes and muscle performance, particularly in the context of high-protein and plant-based diets.
Iván Benito-Vázquez, Pablo Méndez-Albiñana, Aaron Fernández-Quintero et al.· International Journal of Mol...· 0 citations
Lipid droplets (LDs) are the primary organelles responsible for storing neutral lipids. As a key factor in curing, salting has poorly understood effects on intramuscular LDs. In this study, porcine biceps femoris muscles were dry-salted with 1% or 3% NaCl for 3 d, and isolated LDs were subjected to lipidomic analysis (pooled samples). A total of 458 lipid molecules were identified, among which triacylglycerols (132, 28.82%), phosphatidylcholines (58, 12.66%), phosphatidylethanolamines (53, 11.57%), and diacylglycerols (37, 8.08%) were dominant. Multivariate analysis revealed separation among different groups, indicating salt-dependent remodeling of LD lipids. Phospholipid downregulation was extensive, coinciding with reduced LD particle size and suggested altered surface phospholipid composition. Core glycerolipids showed a shift in predominant triacylglycerol species from 56 carbons to 54 (1%) and 50 (3%), reflecting selective remodeling of TG molecular species under enhanced lipolytic conditions. This study provides a subcellular perspective for understanding salt-regulated lipid transformation in meat processing.
Jiajing Pan, Yiying Yu, Guofeng Jin et al.· Food Chemistry· 0 citations
Dysphagia-adapted fluidized meat products alter the protein matrix structure and may impair digestibility. This work evaluated the digestive and nutritional properties of carboxymethyl cellulose (CMC)-modified myofibrillar protein (MP) thickened fluids across three matrices: liquid solution (MP), semisolid state (MP/CMC), and solid gel (MPgel). In vitro digestion indicated all MP matrices exhibited lower digestibility under elderly digestive conditions than adult systems, especially during gastric stage. CMC promoted protein hydrolysis by enhancing the accessibility of MP to pepsin. Digestive kinetics implied that initial and maximal gastric digestion rates of MP/CMC for adults were 13.07- and 3.65-fold higher than those of liquid MP, while dense cross-linked networks reduced digestion extent and rates in MP gel. In vivo, CMC thickening slowed gastrointestinal transit of semisolid MP, sustaining abundant gastric peptides and maintaining high steady-state serum total amino acids in mice. This work provided fundamental insights into the digestive and nutritional characteristics of CMC-induced meat protein-based fluids.
Jiale Chai, Jingjie Wang, Yue Wang et al.· Journal of Agricultural and...· 0 citations
The liver is a metabolically active organ vital for carbohydrate, protein, and lipid metabolism as well as detoxification of harmful substances. Here, we integrated multiple reaction monitoring (MRM) profiling, untargeted lipidomics, and desorption electrospray ionization-mass spectrometry imaging (DESI-MSI) to identify age-associated changes in lipid profiles in the liver of adult mice across three age groups: adult (3–4 months), midaged (10 months), and old (19–21 months). Comparative lipidomic analysis revealed age-dependent remodeling of membrane phospholipids and sphingolipids. Aging was associated with significant alterations of phosphatidylcholines (PC), lysophosphatidylcholines (LPC), phosphatidylserines (PS), phosphatidylethanolamines (PE), and phosphatidylinositols (PI), characterized by reduced levels of unsaturated PC species (PC 36:5, PC 36:4) and saturated PC 32:0 alongside increased LPCs and highly unsaturated PC 40:7. In parallel, sphingolipids were also altered, with increased ceramides (Cer 34:1; O2, CerP 36:1; O2, ACer 59:1; O2) and sphingomyelins (SM 34:1; O2, SM 34:0; O2), and decreased levels of longer-chain sphingomyelins (SM 40:1; O2, SM 42:1; O2, SM 40:2; O2) compared with adult and midaged mice. Additionally, DESI-MSI revealed age-associated changes in monounsaturated (palmitoleic, oleic, eicosenoic) and polyunsaturated (linoleic, docosahexaenoic) fatty acids. These lipid alterations were consistently observed across multiple mass spectrometry platforms, including spatially resolved lipid distributions obtained by DESI-MSI, and are linked to membrane structure, signaling, and metabolism, providing new insights into age-related liver dysfunction.
Punyatoya Panda, C. Ferreira, Allison J. Schaser et al.· Journal of Proteome Research· 0 citations
The functional consequences of consuming conventional and alternative protein rich food matrices remain poorly understood. This study characterized diverse protein rich food matrices and investigated their effect on gut microbiota, muscle protein synthesis, and host metabolic function in rats. Arthropods and lentils contained chitin, resistant starch, polyphenols, and antioxidant activity, whereas egg and picanha were enriched in cholesterol and precursors of trimethylamine N-oxide (TMAO). Lentils and crickets consumption resulted in the lowest fat mass gain, glucose area under the curve and serum lipopolysaccharide (LPS) concentration and lentils the highest fecal butyrate. Gut microbiota alpha diversity was similar among rats fed casein, cricket, acocil, and beef diets, whereas diets containing higher amounts and different types of fat, including egg, picanha, and chinicuil, reduced alpha diversity. Cricket consumption increased the abundance of Faecalibacterium, whereas lentil consumption promoted Bifidobacterium. Rats fed picanha or egg exhibited the highest serum LPS concentrations, while acocil and beef induced the greatest stimulation of muscle protein synthesis followed by cricket, egg, and lentil diets. Biological effects of dietary protein depend on the entire food matrix rather than content alone and cricket and lentil matrices emerge as sustainable protein sources.
Mariana Villegas-Romero, M. Sánchez-Tapia, Julieta Hernández-Acosta et al.· npj Science of Food· 0 citations