Knockout of Stearoyl-CoA Desaturase 1 Decreased Milk Fat and Unsaturated Fatty Acid Contents of the Goat Model Generated by CRISPR/Cas9

Telomere-to-telomere genome assembly of a male goat reveals variants associated with cashmere traits

A complete goat (Capra hircus) reference genome enhances analyses of genetic variation, thus providing insights into domestication and selection in goats and related species. Here, we assemble a telomere-to-telomere (T2T) gap-free genome (2.86 Gb) from a cashmere goat (T2T-goat1.0), including a Y chromosome of 20.96 Mb. With a base accuracy of >99.999%, T2T-goat1.0 corrects numerous genome-wide structural and base errors in previous assemblies and adds 288.5 Mb of previously unresolved regions and 446 newly assembled genes to the reference genome. We sequence the genomes of five representative goat breeds for PacBio reads, and use T2T-goat1.0 as a reference to identify a total of 63,417 structural variations (SVs) with up to 4711 (7.42%) in the previously unresolved regions. T2T-goat1.0 was applied in population analyses of global wild and domestic goats, which revealed 32,419 SVs and 25,397,794 SNPs, including 870 SVs and 545,026 SNPs in the previously unresolved regions. Also, our analyses reveal a set of selective variants and genes associated with domestication (e.g., NKG2D and ABCC4) and cashmere traits (e.g., ABCC4 and ASIP).

Unveiling Novel Mechanism of CIDEB in Fatty Acid Synthesis Through ChIP-Seq and Functional Analysis in Dairy Goat

Goat milk is abundant in nutrients, particularly in milk fats, which confer health benefits to humans. Exploring the regulatory mechanism of fatty acid synthesis is highly important to understand milk composition manipulation. In this study, we used chromatin immunoprecipitation sequencing (ChIP-seq) on goat mammary glands at different lactation stages which revealed a novel lactation regulatory factor: cell death-inducing DFFA-like effector B (CIDEB). RT-qPCR results revealed that CIDEB was significantly upregulated during lactation in dairy goats. CIDEB overexpression significantly increased the expression levels of genes involved in fatty acid synthesis (ACACA, SCD1, p < 0.05; ELOVL6, p < 0.01), lipid droplet formation (XDH, p < 0.05), and triacylglycerol (TAG) synthesis (DGAT1, p < 0.05; GPAM, p < 0.01) in goat mammary epithelial cells (GMECs). The contents of lipid droplets, TAG, and cholesterol were increased (p < 0.05) in CIDEB-overexpressing GMECs, and knockdown of CIDEB led to the opposite results. In addition, CIDEB knockdown significantly decreased the proportion of C16:0 and total C18:2. Luciferase reporter assays indicated that X-box binding protein 1 (XBP1) promoted CIDEB transcription via XBP1 binding sites located in the CIDEB promoter. Furthermore, CIDEB knockdown attenuated the stimulatory effect of XBP1 on lipid droplet accumulation. Collectively, these findings elucidate the critical regulatory roles of CIDEB in milk fat synthesis, thus providing new insights into improving the quality of goat milk.

De novo synthesis of monounsaturated fatty acids modulates exosome-mediated lipid export from human granulosa cells

BACKGROUND

Ovarian somatic cells support the maturation and fertility of oocytes. Metabolic desaturation of fatty acids in these cells has a positive paracrine impact on the maturation of oocytes. We hypothesized that the enzyme stearoyl-CoA desaturase 1 (SCD1) in granulosa cells regulates the lipid cargo of exosomes secreted from these cells by maintaining the balance between saturated and unsaturated lipids. We investigated the effect of SCD1 on exosome lipid content in a cumulus-granulosa cell model under physiologically relevant in vitro conditions.

METHODS

Non-luteinized human COV434 granulosa cells were subjected to treatment with an inhibitor of SCD1 (SCDinhib) alone, in combination with oleic acid, or under control conditions. Subsequently, the exosomes were isolated and characterized via nanoparticle tracking analysis, transmission electron microscopy, and Western blotting. We used liquid chromatography mass spectrometry to investigate the lipidomic profiles. We used quantitative PCR with TaqMan primers to assess the expression of genes involved in lipogenesis and control of cell cycle progression.

RESULTS

A trend toward exosome production was observed with a shift toward smaller exosome sizes in cells treated with SCD1inhib. This trend reached statistical significance when SCDinhib was combined with oleic acid supplementation. SCD1 inhibition led to the accumulation of saturated omega-6 lipids in exosomes. The latter effect was reversed by oleic acid supplementation, which also improved exosome production and suppressed the expression of fatty acid synthase and Cyclin D2.

CONCLUSION

These findings underscore the critical role of de novo fatty acid desaturation in the regulation of the export of specific lipids through exosomes, with potential implications for controlling intercellular communication within the ovary.

Genome editing: An insight into disease resistance, production efficiency, and biomedical applications in livestock

One of the primary concerns for the survival of the human species is the growing demand for food brought on by an increasing global population. New developments in genome-editing technology present promising opportunities for the growth of wholesome and prolific farm animals. Genome editing in large animals is used for a variety of purposes, including biotechnology to improve food production, animal health, and pest management, as well as the development of animal models for fundamental research and biomedicine. Genome editing entails modifying genetic material by removing, adding, or manipulating particular DNA sequences from a particular locus in a way that does not happen naturally. The three primary genome editors are CRISPR/Cas 9, TALENs, and ZFNs. Each of these enzymes is capable of precisely severing nuclear DNA at a predetermined location. One of the most effective inventions is base editing, which enables single base conversions without the requirement for a DNA double-strand break (DSB). As reliable methods for precise genome editing in studies involving animals, cytosine and adenine base editing are now well-established. Effective zygote editing with both cytosine and adenine base editors (ABE) has resulted in the production of animal models. Both base editors produced comparable outcomes for the precise editing of point mutations in somatic cells, advancing the field of gene therapy. This review focused on the principles, methods, recent developments, outstanding applications, the advantages and disadvantages of ZFNs, TALENs, and CRISPR/Cas9 base editors, and prime editing in diverse lab and farm animals. Additionally, we address the methodologies that can be used for gene regulation, base editing, and epigenetic alterations, as well as the significance of genome editing in animal models to better reflect real disease. We also look at methods designed to increase the effectiveness and precision of gene editing tools. Genome editing in large animals is used for a variety of purposes, including biotechnology to improve food production, animal health, and pest management, as well as the development of animal models for fundamental research and biomedicine. This review is an overview of the existing knowledge of the principles, methods, recent developments, outstanding applications, the advantages and disadvantages of zinc finger nucleases (ZFNs), transcription-activator-like endonucleases (TALENs), and clustered regularly interspaced short palindromic repeats associated protein 9 (CRISPR/Cas 9), base editors and prime editing in diverse lab and farm animals, which will offer better and healthier products for the entire human race.

MiR-103-5p deficiency suppresses lipid accumulation via upregulating PLSCR4 and its host gene PANK3 in goat mammary epithelial cells

Lipids are intimately related to the unique flavor and nutritional values of goat milk. MicroRNAs (miRNA) participate in the regulation of various biological functions, including the synthesis and degradation of lipids. Several studies have shown that miR-103 is involved in the regulation of lipid metabolism, however, the molecular mechanism by which miR-103 regulates lipid metabolism in goat mammary gland is poorly understood. In this study, miR-103 was knocked out in goat mammary epithelial cells (GMECs) by CRISPR/Cas9, and the accumulation of lipid droplets, triglycerides, and cholesterol in the cells was suppressed subsequently. Overexpression or knockdown of miR-103-5p and miR-103-3p in GMECs revealed that it was miR-103-5p that promoted lipid accumulation but not miR-103-3p. In addition, Pantothenate Kinase 3 (PANK3), the host gene of miR-103, and Phospholipid Scramblase 4 (PLSCR4) were identified as the target genes of miR-103-5p by dual fluorescein and miRNA pulldown. Furthermore, we identified that cellular lipid levels were negatively regulated by PANK3 and PLSCR4. Lastly, in miR-103 knockout GMECs, the knockdown of PANK and PLSCR4 rescued the lipid accumulation. These findings suggest that miR-103-5p promotes lipid accumulation by targeting PLSCR4 and the host gene PANK3 in GMECs, providing new insights for the regulation of goat milk lipids via miRNAs.

Knockdown of PROX1 promotes milk fatty acid synthesis by targeting PPARGC1A in dairy goat mammary gland

Goat milk is rich in various fatty acids that are beneficial to human health. Chromatin immunoprecipitation followed by sequencing (ChIP-seq) and RNA-seq analyses of goat mammary glands at different lactation stages revealed a novel lactation regulatory factor, Prospero homeobox 1 (PROX1). However, the mechanism whereby PROX1 regulates lipid metabolism in dairy goats remains unclear. We found that PROX1 exhibits the highest expression level during peak lactation period. PROX1 knockdown enhanced the expression of genes related to de novo fatty acid synthesis (e.g., SREBP1 and FASN) and triacylglycerol (TAG) synthesis (e.g., DGAT1 and GPAM) in goat mammary epithelial cells (GMECs). Consistently, intracellular TAG and lipid droplet contents were significantly increased in PROX1 knockdown cells and reduced in PROX1 overexpression cells, and we observed similar results in PROX1 knockout mice. Following PROX1 overexpression, RNA-seq showed a significant upregulation of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PPARGC1A) expression. Further, PPARGC1A knockdown attenuated the inhibitory effects of PROX1 on TAG contents and lipid-droplet formation in GMECs. Moreover, we found that PROX1 promoted PPARGC1A transcription via the PROX1 binding sites (PBSs) located in the PPARGC1A promoter. These results suggest a novel target for manipulating the goat milk-fat composition and improving the quality of goat milk.

Sodium acetate regulates milk fat synthesis through the activation of GPR41/GPR43 signaling pathway

Background

Fat is a critical component in milk, which provided energy for the early growth and development of mammals. Milk fat is positively related to the concentration of acetate in the blood, while the underlying mechanism is still unclear.

Objective

This study is to investigate the effects of sodium acetate (NaAc) on milk fat synthesis in the mammary gland, and explored the underlying mechanism.

Methods

In vitro experiments were carried out in mouse mammary epithelial cell line (HC11) cells cultured with NaAc to explore the potential pathway of NaAc on milk fat synthesis. Furthermore, 24 pregnant mice (from d 18.5 of gestation to d 7 of lactation, exposed to 200 mM NaAc drinking water) were used as an in vivo model to verify the results.

Results

In this study, we found that NaAc promoted milk fat synthesis and the expression of related genes and proteins in HC11 mammary epithelial cells with the activation of GPCR and mTORC1 signaling pathways (p &lt; 0.05). Pretreatment with the mTORC1 inhibitors and G protein inhibitors attenuated the NaAc-induced milk fat synthesis in HC11 mammary epithelial cells (p &lt; 0.05). Importantly, the effect of NaAc on milk synthesis was attenuated in GPR41 and GPR43 knockdown HC11 mammary epithelial cells (p &lt; 0.05). This evidence indicates that NaAc might regulate milk fat synthesis through the GPR41/GPR43-mTORC1 pathway. Consistently, in in vivo experiment, dietary supplementation with NaAc significantly increased milk fat content and fat synthesis-related proteins in mice mammary glands with the activation of mTORC1 and GPCR signaling pathways at peak lactation (p &lt; 0.05).

Conclusion

The addition of NaAc promoted the increase of milk fat synthesis in HC11 mammary epithelial cells and mice mammary glands at peak lactation. Mechanistically, NaAc activates GPR41 and GPR43 receptors, leading to the activation of the mTORC1 signaling pathway to promote the synthesis of milk fat.

Acetate-Induced Milk Fat Synthesis Is Associated with Activation of the mTOR Signaling Pathway in Bovine Mammary Epithelial Cells

Acetate is a precursor substance for fatty acid synthesis in bovine mammary epithelial cells (BMECs), and the mTOR signaling pathway plays an important role in milk fat synthesis. However, the mechanism of the regulatory effects of acetate on lipogenic genes via the mTOR signaling pathway in BMEC remains unknown. We hypothesized that acetate can enhance the expression of lipogenic genes and triglyceride (TG) production by activating the mTOR signaling pathway in BMECs. Therefore, the aim of this study was to investigate the network of acetate-regulated lipid metabolism by the mTOR signaling pathway in BMECs. These results showed that TG synthesis was elevated (p < 0.01) in BMECs with acetate treatment. The lipid droplets were increased in the acetate-treated groups compared with those in the control group through the Bodipy staining of the lipids. In addition, the fatty acid profile in BMECs treated with acetate was affected, with an elevation in the proportions of C14:0, C16:0, and C18:0. The mRNA levels of the sterol-response-element-binding protein 1 (SREBP1), stearoyl-CoA desaturase 1 (SCD1), and fatty acid synthase (FAS) genes involved in the lipogenesis and transcriptional factors were upregulated (p < 0.05) in BMECs with acetate treatment. Remarkably, the expression of acetyl-CoA carboxylase α (ACCα) and FAS rate-limiting enzymes involved in lipogenesis was upregulated in BMECs with acetate treatment. Moreover, the addition of acetate enhanced the key protein expression of S6K1, which is related to the mTOR signaling pathway. Taken together, our data suggest that TG accumulation and expression of lipogenic genes induced by acetate are associated with the activation of the mTOR signaling pathway, which provides new insights into the understanding of the molecular mechanism in the expression of mTOR-signaling-pathway-regulated lipogenic genes.

Mechanism of SCD Participation in Lipid Droplet-Mediated Steroidogenesis in Goose Granulosa Cells

Stearoyl-CoA desaturase (SCD) is a key enzyme catalyzing the rate-limiting step in monounsaturated fatty acids (MUFAs) production. There may be a mechanism by which SCD is involved in lipid metabolism, which is assumed to be essential for goose follicular development. For this reason, a cellular model of SCD function in goose granulosa cells (GCs) via SCD overexpression and knockdown was used to determine the role of SCD in GC proliferation using flow cytometry. We found that SCD overexpression induced and SCD knockdown inhibited GCs proliferation. Furthermore, ELISA analysis showed that SCD overexpression increased the total cholesterol (TC), progesterone, and estrogen levels in GCs, while SCD knockdown decreased TC, progesterone, and estrogen levels (p < 0.05). Combining these results with those of related multi-omics reports, we proposed a mechanism of SCD regulating the key lipids and differentially expressed gene (DEGs) in glycerophospholipid and glycerolipid metabolism, which participate in steroidogenesis mediated by the lipid droplet deposition in goose GCs. These results add further insights into understanding the lipid metabolism mechanism of goose GCs.

Application of Gene Editing Technology in Resistance Breeding of Livestock

As a new genetic engineering technology, gene editing can precisely modify the specific gene sequence of the organism’s genome. In the last 10 years, with the rapid development of gene editing technology, zinc-finger nucleases (ZFNs), transcription activator-like endonucleases (TALENs), and CRISPR/Cas9 systems have been applied to modify endogenous genes in organisms accurately. Now, gene editing technology has been used in mice, zebrafish, pigs, cattle, goats, sheep, rabbits, monkeys, and other species. Breeding for disease-resistance in agricultural animals tends to be a difficult task for traditional breeding, but gene editing technology has made this easier. In this work, we overview the development and application of gene editing technology in the resistance breeding of livestock. Also, we further discuss the prospects and outlooks of gene editing technology in disease-resistance breeding.