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MiR-103 controls milk fat accumulation in goat (Capra hircus) mammary gland during lactation.

Lin X, Luo J, Zhang L, Wang W, Gou D - PLoS ONE (2013)

Bottom Line: Further studies revealed that miR-103 expression correlates with the lactation.Further functional analysis showed that over-expression of miR-103 in mammary gland epithelial cells increases transcription of genes associated with milk fat synthesis, resulting in an up-regulation of fat droplet formation, triglyceride accumulation, and the proportion of unsaturated fatty acids.This study provides new insight into the functions of miR-103, as well as the molecular mechanisms that regulate milk fat synthesis.

View Article: PubMed Central - PubMed

Affiliation: Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China.

ABSTRACT
Milk is the primary source of nutrition for young mammals including humans. The nutritional value of milk is mainly attributable to fats and proteins fractions. In comparison to cow milk, goat milk contains greater amounts of total fat, including much higher levels of the beneficial unsaturated fatty acids. MicroRNAs (miRNAs), a well-defined group of small RNAs containing about 22 nucleotides (nt), participate in various metabolic processes across species. However, little is known regarding the role of miRNAs in regulating goat milk composition. In the present study, we performed high-throughput sequencing to identify mammary gland-enriched miRNAs in lactating goats. We identified 30 highly expressed miRNAs in the mammary gland, including miR-103. Further studies revealed that miR-103 expression correlates with the lactation. Further functional analysis showed that over-expression of miR-103 in mammary gland epithelial cells increases transcription of genes associated with milk fat synthesis, resulting in an up-regulation of fat droplet formation, triglyceride accumulation, and the proportion of unsaturated fatty acids. This study provides new insight into the functions of miR-103, as well as the molecular mechanisms that regulate milk fat synthesis.

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The top 30 miRNAs with maximum number of reads count in goat mammary gland during mid-lactation.RNA samples were pooled from 10 individuals during mid-lactation (120 days after parturition). The top 30 miRNAs in mammary gland were identified by Solexa sequencing and clustered based on their reported function (Table S2). Values on X-axis indicate the number of reads count of miRNAs. All goat miRNAs are named after bovine (Bos taurus). “R+1” and“L-1”: compared to bovine's sequence, goat miRNA sequence has addition or reduction of one base on the 3′ or 5′end.
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pone-0079258-g001: The top 30 miRNAs with maximum number of reads count in goat mammary gland during mid-lactation.RNA samples were pooled from 10 individuals during mid-lactation (120 days after parturition). The top 30 miRNAs in mammary gland were identified by Solexa sequencing and clustered based on their reported function (Table S2). Values on X-axis indicate the number of reads count of miRNAs. All goat miRNAs are named after bovine (Bos taurus). “R+1” and“L-1”: compared to bovine's sequence, goat miRNA sequence has addition or reduction of one base on the 3′ or 5′end.

Mentions: 823 conserved miRNAs were identified and subjected to the estimation of their relative abundance. Interestingly, we found that the top 30 most abundantly expressed miRNAs constitute 21.18% of the total miRNAs and they are all conserved miRNAs. We categorized these 30 miRNAs into seven clusters based on their previously reported functions (Figure 1 and Table S2), which included proliferation and apoptosis, immune response and development, lipid metabolism, and epithelial phenotype conferring. Prior to lactation, mammary glands proliferate at a high rate to generate a vast number of epithelial cells [25]. During lactation, mammary gland epithelial cells are responsible for milk fat synthesis and fat globule secretion, which is regulated by the action of several hormones (i.e., insulin) [36]. In the mammary glands of lactating goats, we found that miRNAs associated with cell proliferation (miR-26a, miR-21), conferring epithelial phenotype (miR-29a, miR-30a/d), immune response and development (miR-181, let-7a/b/f/g/i) were abundantly expressed, as well as miRNAs involved in lipid metabolism (miR-103, miR-23a, miR-27b, miR-200a/b/c). Specifically, miR-26a (cell proliferation) was the most abundantly expressed, followed by miR-148 (may control insulin content) and miR-21 (cell proliferation). These data suggest that miRNAs play a critical role in mammary gland regulation and cell proliferation, as well as immune responses, and lipid metabolism. Specific knockdown of miR-148 in pancreatic β-cells or in isolated primary islets down-regulates insulin mRNA levels [37]. Mammary gland does not synthesize insulin, therefore miR-148 is not included in the “lipid metabolism” cluster. Moreover, miR-143 and miR-145, are highly expressed in adipose tissue, and are also abundantly expressed in the goat mammary glands as well, suggesting the same regulatory function of some miRNAs in mammary glands and adipose tissue.


MiR-103 controls milk fat accumulation in goat (Capra hircus) mammary gland during lactation.

Lin X, Luo J, Zhang L, Wang W, Gou D - PLoS ONE (2013)

The top 30 miRNAs with maximum number of reads count in goat mammary gland during mid-lactation.RNA samples were pooled from 10 individuals during mid-lactation (120 days after parturition). The top 30 miRNAs in mammary gland were identified by Solexa sequencing and clustered based on their reported function (Table S2). Values on X-axis indicate the number of reads count of miRNAs. All goat miRNAs are named after bovine (Bos taurus). “R+1” and“L-1”: compared to bovine's sequence, goat miRNA sequence has addition or reduction of one base on the 3′ or 5′end.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3823599&req=5

pone-0079258-g001: The top 30 miRNAs with maximum number of reads count in goat mammary gland during mid-lactation.RNA samples were pooled from 10 individuals during mid-lactation (120 days after parturition). The top 30 miRNAs in mammary gland were identified by Solexa sequencing and clustered based on their reported function (Table S2). Values on X-axis indicate the number of reads count of miRNAs. All goat miRNAs are named after bovine (Bos taurus). “R+1” and“L-1”: compared to bovine's sequence, goat miRNA sequence has addition or reduction of one base on the 3′ or 5′end.
Mentions: 823 conserved miRNAs were identified and subjected to the estimation of their relative abundance. Interestingly, we found that the top 30 most abundantly expressed miRNAs constitute 21.18% of the total miRNAs and they are all conserved miRNAs. We categorized these 30 miRNAs into seven clusters based on their previously reported functions (Figure 1 and Table S2), which included proliferation and apoptosis, immune response and development, lipid metabolism, and epithelial phenotype conferring. Prior to lactation, mammary glands proliferate at a high rate to generate a vast number of epithelial cells [25]. During lactation, mammary gland epithelial cells are responsible for milk fat synthesis and fat globule secretion, which is regulated by the action of several hormones (i.e., insulin) [36]. In the mammary glands of lactating goats, we found that miRNAs associated with cell proliferation (miR-26a, miR-21), conferring epithelial phenotype (miR-29a, miR-30a/d), immune response and development (miR-181, let-7a/b/f/g/i) were abundantly expressed, as well as miRNAs involved in lipid metabolism (miR-103, miR-23a, miR-27b, miR-200a/b/c). Specifically, miR-26a (cell proliferation) was the most abundantly expressed, followed by miR-148 (may control insulin content) and miR-21 (cell proliferation). These data suggest that miRNAs play a critical role in mammary gland regulation and cell proliferation, as well as immune responses, and lipid metabolism. Specific knockdown of miR-148 in pancreatic β-cells or in isolated primary islets down-regulates insulin mRNA levels [37]. Mammary gland does not synthesize insulin, therefore miR-148 is not included in the “lipid metabolism” cluster. Moreover, miR-143 and miR-145, are highly expressed in adipose tissue, and are also abundantly expressed in the goat mammary glands as well, suggesting the same regulatory function of some miRNAs in mammary glands and adipose tissue.

Bottom Line: Further studies revealed that miR-103 expression correlates with the lactation.Further functional analysis showed that over-expression of miR-103 in mammary gland epithelial cells increases transcription of genes associated with milk fat synthesis, resulting in an up-regulation of fat droplet formation, triglyceride accumulation, and the proportion of unsaturated fatty acids.This study provides new insight into the functions of miR-103, as well as the molecular mechanisms that regulate milk fat synthesis.

View Article: PubMed Central - PubMed

Affiliation: Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China.

ABSTRACT
Milk is the primary source of nutrition for young mammals including humans. The nutritional value of milk is mainly attributable to fats and proteins fractions. In comparison to cow milk, goat milk contains greater amounts of total fat, including much higher levels of the beneficial unsaturated fatty acids. MicroRNAs (miRNAs), a well-defined group of small RNAs containing about 22 nucleotides (nt), participate in various metabolic processes across species. However, little is known regarding the role of miRNAs in regulating goat milk composition. In the present study, we performed high-throughput sequencing to identify mammary gland-enriched miRNAs in lactating goats. We identified 30 highly expressed miRNAs in the mammary gland, including miR-103. Further studies revealed that miR-103 expression correlates with the lactation. Further functional analysis showed that over-expression of miR-103 in mammary gland epithelial cells increases transcription of genes associated with milk fat synthesis, resulting in an up-regulation of fat droplet formation, triglyceride accumulation, and the proportion of unsaturated fatty acids. This study provides new insight into the functions of miR-103, as well as the molecular mechanisms that regulate milk fat synthesis.

Show MeSH