Circ003429 Regulates Unsaturated Fatty Acid Synthesis in the Dairy Goat Mammary Gland by Interacting with miR-199a-3p, Targeting the YAP1 Gene

Circular RNA_015343 sponges microRNA-25 to regulate viability, proliferation, and milk fat synthesis of ovine mammary epithelial cells via INSIG1

In our previous study, circ_015343 was found to inhibit the viability and proliferation of ovine mammary epithelial cells (OMECs) and the expression levels of milk fat synthesis marker genes, but the regulatory mechanism underlying the processes is still unclear. Accordingly in this study, the target relationships between circ_015343 with miR-25 and between miR-25 with insulin induced gene 1 (INSIG1) were verified, and the functions of miR-25 and INSIG1 were investigated in OMECs. The dual-luciferase reporter assay revealed that miR-25 mimic remarkably decreased the luciferase activity of circ_015343 in HEK293T cells cotransfected with a wild-type vector, while it did not change the activity of circ_015343 in HEK293T cells cotransfected with a mutant vector. These suggest that cic_015343 can adsorb and bind miR-25. The miR-25 increased the viability and proliferation of OMECs, and the content of triglycerides in OMECs. In addition, INSIG1 was found to be a target gene of miR-25 using a dual-luciferase reporter assay. Overexpression of INSIG1 decreased the viability, proliferation, and level of triglycerides of OMECs. In contrast, the inhibition of INSIG1 in expression had the opposite effect on activities and triglycerides of OMECs with overexpressed INSIG1. A rescue experiment revealed that circ_015343 alleviated the inhibitory effect of miR-25 on the mRNA and protein abundance of INSIG1. These results indicate that circ_015343 sponges miR-25 to inhibit the activities and content of triglycerides of OMECs by upregulating the expression of INSIG1 in OMECs. This study provided new insights for understanding the genetic molecular mechanism of lactation traits in sheep.

Research Progress on Genomic Regions and Candidate Genes Related to Milk Composition Traits of Dairy Goats Based on Functional Genomics: A Narrative Review

BACKGROUND

Goat milk has gained global attention for its unique nutritional properties and potential health benefits. Advancements in functional genomic technologies have significantly progressed genetic research on milk composition traits in dairy goats.

RESULTS

This review summarizes various research methodologies applied in this field. Genome-wide association studies (GWAS) have identified genomic regions associated with major milk components, with the diacylglycerol acyltransferase 1 (DGAT1) gene and casein gene cluster consistently linked to milk composition traits. Transcriptomics has revealed gene expression patterns in mammary tissue across lactation stages, while the role of non-coding RNAs (such as miRNAs and circRNAs) in regulating milk composition has been confirmed. Proteomic and metabolomic studies have not only helped us gain a more comprehensive understanding of goat milk composition characteristics but have also provided crucial support for the functional validation of genes related to milk components. The integration of multi-omics data has emerged as an effective strategy for elucidating complex regulatory networks from a systems biology perspective.

CONCLUSIONS

Despite progress, challenges remain, including refining reference genomes, collecting large-scale phenotypic data, and conducting functional validations. Future research should focus on improving reference genomes, expanding study populations, investigating functional milk components, exploring epigenetic regulation and non-coding RNAs, and studying microbiome-host genome interactions. These efforts will inform more precise genomic and marker-assisted selection strategies, advancing genetic improvements in milk composition traits in dairy goats.

Milk Lipid Regulation in Dairy Goats: A Comprehensive Review

The growth, development, and milk production traits of dairy goats, which are important sources of high-quality animal protein, are significantly influenced by a combination of genetic and environmental factors. It is imperative to identify key genetic loci that govern economically valuable traits in order to enhance breeding programs. Despite advancements in genomic technologies, there are still gaps in knowledge regarding the interplay between genetic factors and environmental influences, particularly in relation to the regulation of milk production and quality. Therefore, the aim of this paper was to synthesize advancements in the genetic and environmental factors affecting milk production and quality in dairy goats and identify key regulatory mechanisms. This review summarizes the recent progress on the identification of genes associated with milk production traits using whole-genome resequencing, the use of transcriptomic profiling to identify genes linked to milk production, the exploration of regulatory mechanisms of lipid metabolism in goat mammary epithelial cells, and the evaluation of the influence of nutritional factors on milk quality. A comprehensive understanding of these interactions is essential for enhancing breeding strategies and ensuring the sustainability of dairy goat farming. Future research should incorporate multi-omics approaches to unravel the intricate regulatory processes governing milk production and adapt practices to meet global demand while upholding economic and environmental sustainability.

Lipid Regulatory Element Interact with CD44 on Mitochondrial Bioenergetics in Bovine Adipocyte Differentiation and Lipometabolism

The CD44 gene is a critical factor in animal physiological processes and has been shown to affect insulin resistance and fat accumulation in mammals. Nevertheless, little research has been conducted on its precise functions in lipid metabolism and adipogenic differentiation in beef cattle. This study analyzed the expression of CD44 and miR-199a-3p during bovine preadipocyte differentiation. The luciferase reporter assay demonstrated that CD44 was a direct target of miR-199a-3p. Increased accumulation of lipid droplets and triglyceride levels, altered fatty acid metabolism, and accelerated preadipocyte differentiation were all caused by the upregulation of miR-199a-3p or a reduction in CD44 expression. CD44 knockdown upregulated the expression of adipocyte-specific genes (LPL and FABP4) and altered the levels of lipid metabolites (SOPC, l-arginine, and heptadecanoic acid). Multiomics highlights enriched pathways involved in energy metabolism (MAPK, cAMP, and calcium signaling) and shifts in mitochondrial respiration and glycolysis, indicating that CD44 plays a regulatory role in lipid metabolism. The findings show that intracellular lipolysis, glycolysis, mitochondrial respiration, fat deposition, and lipid droplet composition are all impacted by miR-199a-3p, which modulates CD44 in bovine adipocytes.

Understanding Circular RNAs in Health, Welfare, and Productive Traits of Cattle, Goats, and Sheep

Circular RNAs (circRNAs) are unique noncoding RNA molecules, notable for their covalent closed-loop structures, which play a crucial role in regulating gene expression across a variety of biological processes. This review comprehensively synthesizes the existing knowledge of circRNAs in three key livestock species: Bos taurus (cattle), Ovis aries (sheep), and Capra hircus (goats). It focuses on their functional importance and emerging potential as biomarkers for disease detection, stress response, and overall physiological health. Specifically, it delves into the expression and functionality of circRNAs in these species, paying special attention to traits critical to livestock productivity such as milk production, meat quality, muscle development, wool production, immune responses, etc. We also address the current challenges faced in circRNA research, including the need for standardized methodologies and broader studies. By providing insights into the molecular mechanisms regulated by circRNAs, this review underscores their scientific and economic relevance in the livestock industry. The potential of circRNAs to improve animal health management and the quality of animal-derived products aligns with growing consumer concerns for animal welfare and sustainability. Thus, this paper aims to guide future research directions while supporting the development of innovative strategies in livestock management and breeding.

Effects of dietary Clostridium butyricum and rumen protected fat on meat quality, oxidative stability, and chemical composition of finishing goats

BACKGROUND

Clostridium butyricum (CB) is a probiotic that can regulate intestinal microbial composition and improve meat quality. Rumen protected fat (RPF) has been shown to increase the dietary energy density and provide essential fatty acids. However, it is still unknown whether dietary supplementation with CB and RPF exerts beneficial effects on growth performance and nutritional value of goat meat. This study aimed to investigate the effects of dietary CB and RPF supplementation on growth performance, meat quality, oxidative stability, and meat nutritional value of finishing goats. Thirty-two goats (initial body weight, 20.5 ± 0.82 kg) were used in a completely randomized block design with a 2 RPF supplementation (0 vs. 30 g/d) × 2 CB supplementation (0 vs. 1.0 g/d) factorial treatment arrangement. The experiment included a 14-d adaptation and 70-d data and sample collection period. The goats were fed a diet consisted of 400 g/kg peanut seedling and 600 g/kg corn-based concentrate (dry matter basis).

RESULT

Interaction between CB and RPF was rarely observed on the variables measured, except that shear force was reduced (P < 0.05) by adding CB or RPF alone or their combination; the increased intramuscular fat (IMF) content with adding RPF was more pronounced (P < 0.05) with CB than without CB addition. The pH24h (P = 0.009), a* values (P = 0.007), total antioxidant capacity (P = 0.050), glutathione peroxidase activities (P = 0.006), concentrations of 18:3 (P < 0.001), 20:5 (P = 0.003) and total polyunsaturated fatty acids (P = 0.048) were increased, whereas the L* values (P < 0.001), shear force (P = 0.050) and malondialdehyde content (P = 0.044) were decreased by adding CB. Furthermore, CB supplementation increased essential amino acid (P = 0.027), flavor amino acid (P = 0.010) and total amino acid contents (P = 0.024) as well as upregulated the expression of lipoprotein lipase (P = 0.034) and peroxisome proliferator-activated receptor γ (PPARγ) (P = 0.012), and downregulated the expression of stearoyl-CoA desaturase (SCD) (P = 0.034). The RPF supplementation increased dry matter intake (P = 0.005), averaged daily gain (trend, P = 0.058), hot carcass weight (P = 0.046), backfat thickness (P = 0.006), concentrations of 16:0 (P < 0.001) and c9-18:1 (P = 0.002), and decreased the shear force (P < 0.001), isoleucine (P = 0.049) and lysine content (P = 0.003) of meat. In addition, the expressions of acetyl-CoA carboxylase (P = 0.003), fatty acid synthase (P = 0.038), SCD (P < 0.001) and PPARγ (P = 0.022) were upregulated due to RPF supplementation, resulting in higher (P < 0.001) content of IMF.

CONCLUSIONS

CB and RPF could be fed to goats for improving the growth performance, carcass traits and meat quality, and promote fat deposition by upregulating the expression of lipogenic genes of Longissimus thoracis muscle.

Progress in epigenetic regulation of milk synthesis, with particular emphasis on mRNA regulation and DNA methylation

Inadequate milk secretion and a lack of nutrients in humans and mammals are serious problems. It is of great significance to clarify the mechanisms of milk synthesis and treatment methods. Epigenetic modification, represented by RNA methylation, is an important way of gene expression regulation that profoundly affects human gene expression and participates in various physiological and pathological mechanisms. Epigenetic disorders also have an important impact on the production and secretion of milk. This review systematically summarized the research results of epigenetics in the process of lactation in PubMed, Web of Science, NSTL, and other databases and reviewed the effects of epigenetics on human and mammalian lactation, including miRNAs, circRNAs, lncRNAs, DNA methylations, and RNA methylations. The abnormal expression of miRNAs was closely related to the synthesis and secretion of milk fat, milk protein, and other nutrients in the milk of cattle, sheep, and other mammals. MiRNAs are also involved in the synthesis of human milk and the secretion of nutrients. CircRNAs and lncRNAs mainly target miRNAs and regulate the synthesis of nutrients in milk by ceRNA mechanisms. The abnormal expression of DNA and RNA methylation also has an important impact on milk synthesis. Epigenetic modification has the potential to regulate the milk synthesis of breast epithelial cells. Analyzing the mechanisms of human and mammalian milk secretion deficiency and nutrient deficiency from the perspective of epigenetics will provide a new perspective for the treatment of postpartum milk deficiency in pregnant women and mammalian milk secretion deficiency.

CircRNA-02191 regulating unsaturated fatty acid synthesis by adsorbing miR-145 to enhance CD36 expression in bovine mammary gland

CD36 functions as a receptor for long-chain fatty acids, promoting the absorption and transport of long-chain unsaturated fatty acids. However, the regulatory influence of upstream circRNAs or miRNAs on its expression in cow mammary gland remains unclear. Herein, we performed high-throughput sequencing to screen for differentially expressed miRNAs and mRNAs in bovine mammary tissue during the late-lactation and the dry period to screen and conducted bioinformatics analysis to identify 420 miRNA/mRNA pairs, including miR-145/CD36. Experimental results indicate that miR-145 can directly target CD36 and inhibit its expression. Additionally, the circRNA-02191 sequence is predicted to contain a miR-145 binding site. As shown by dual luciferase reporter system detection, circRNA-02191 bound to miR-145 and its overexpression significantly reduced the expression of miR-145. Furthermore, the overexpression of miR-145 inhibited triglyceride accumulation, while circRNA-02191 enhanced the expression of the miR-145 target gene CD36. The above results indicate that circRNA-02191 can regulate triglyceride and fatty acid components by binding miR-145 and subsequently alleviating the inhibitory effect of miR-145 on the expression of CD36. Taken together, these findings present a novel approach to improve milk quality by analyzing the regulatory effect and mechanism regulating the circ02191/miR-145/CD36 pathway on fatty acid synthesis in the mammary gland of dairy cows.

Non-coding transcriptomic profiles in the sheep mammary gland during different lactation periods

Sheep milk production is a dynamic and multifactorial trait regulated by diverse biological mechanisms. To improve the quality and production of sheep milk, it is necessary to understand the underlying non-coding transcriptomic mechanisms. In this study, ribonucleic acid-sequencing (RNA-seq) was used to profile the expression of microRNAs (miRNAs) and circular RNAs (circRNAs) in the sheep mammary gland at three key lactation time points (perinatal period, PP; early lactation, EL; and peak lactation, PL). A total of 2,369 novel circRNAs and 272 miRNAs were profiled, of which 348, 373, and 36 differentially expressed (DE) circRNAs and 30, 34, and 7 DE miRNAs were detected in the comparison of EL vs. PP, PL vs. PP, and PL vs. EL, respectively. A series of bioinformatics analyses including functional enrichment, machine learning prediction, and competing endogenous RNA (ceRNA) network analyses were conducted to identify subsets of the potential candidate miRNAs (e.g., oar_miR_148a, oar_miR_362, and oar_miR_432) and circRNAs (e.g., novel_circ_0011066, novel_circ_0010460, and novel_circ_0006589) involved in sheep mammary gland development. Taken together, this study offers a window into the dynamics of non-coding transcriptomes that occur during sheep lactation and may provide further insights into miRNA and circRNA that influence sheep mammary gland development.

Circ007071 Inhibits Unsaturated Fatty Acid Synthesis by Interacting with miR-103-5p to Enhance PPARγ Expression in the Dairy Goat Mammary Gland

Understanding more precisely the mechanisms controlling the metabolism of fatty acid in the mammary gland of dairy goats is essential for future improvements in milk quality. Particularly since recent data have underscored a key role for circular RNAs (circRNAs) in the mammary gland function, high-throughput sequencing technology was used to identify expression levels of circRNAs in the mammary tissue of dairy goats during early and peak lactation in the present study. Compared with early lactation, results demonstrated that the expression level of circ007071 during peak lactation was 12.02-fold up-regulated. Subsequent studies in goat mammary epithelial cells (GMECs) revealed that circ007071 stimulated the synthesis of triglycerides (TAG) and cholesterol, as well as increased the content of saturated fatty acids (C16:0 and C18:0). More importantly, using a double luciferase reporting system allowed us to detect the circ007071 sequence at a binding site of miR-103-5p, indicating that it targeted this miRNA. Overexpression of circ007071 significantly decreased the abundance of miR-103-5p and led to inhibition of TAG synthesis. In contrast, the abundance of peroxisome proliferator-activated receptor γ (PPARγ), a target gene of miR-103-5p, was reinforced with the overexpression of circ007071. Thus, we conclude that one key function of circ007071 in the regulation of milk fat synthesis is to attenuate the inhibitory effect of miR-103-5p on PPARγ via direct interactions with miRNA. As a result, the process of TAG and saturated fatty acid is able to proceed.