The effects of arginine on gene expression in bovine mammary and longissimus dorsi tissues.

Citation

J. Dairy Sci. Vol. 105, Suppl. 1, Page 395. (abs. 2435V).

Résumé en langage clair

The objective of this study was to determine effects of Arg supply on expression of a select set of genes related to AA metabolism and nutrient partitioning in mammary and longissimus dorsi tissues. Six rumen-cannulated, lactating Holstein cows were used in a replicated 3 × 3 Latin square design with 14-d periods. Treatments were continuous abomasal infusion that supplied 0 (ARGx0), 49.2 (ARGx1), and 98.4 (ARGx2) g/d Arg in an otherwise complete AA mixture at 900 g/d: ARGx1 treatment profiled the rumen microbial AA and met MP
requirements. Tissue samples collected by biopsy on d 14 were analyzed by RT-qPCR relative to stably expressed genes for each tissue. The Arg dose effects were tested for contrasts (PL = linear; PQ = quadratic). Arg infusion increased mammary mRNA expression of genes involved in proline (Pro) synthesis (OAT (PL = 0.04; PQ = 0.06), PYCR1 (PL = 0.01)) and tended to decrease PYCR1 in muscle (PL = 0.13; PQ = 0.06). Other Arg metabolism genes (ASL, ASS1, ARG2) were decreased in ARGx1 in muscle (PQ < 0.04). Arg infusion decreased AA transporter SLC38A9, but increased SLC7A1, SLC7A5, and SLC7A8, mTORC1 regulators CASTOR1 and LAMTOR4, and ribosomal RNA18S1 in mammary tissue (PL < 0.05) but not in muscle (PL ≥ 0.16), indicating mammary-specific upregulation of protein synthesis. Of the vascular function genes, Arg supply increased mammary NOS3 (PQ = 0.08), FLT1 (PL = 0.05; PQ = 0.01), KDR (PQ = 0.11), and TEK (PL = 0.13; PQ = 0.12), whereas muscle exhibited a decrease for BDKRB2 (PL < 0.01; PQ < 0.01), TEK (PQ = 0.03), ANGPT2 (PQ = 0.11), and VEGFA (PQ = 0.11). The transcription factor response to Arg was different between tissues. In mammary, Arg supply increased ATF4 (PL = 0.03), whereas ARGx1 tended to increase ATF6 (PQ = 0.07), and decreased FOS (PQ = 0.05). In muscle, ARGx1 decreased ATF6 (PQ = 0.02), but increased JUN (PL < 0.01) and FOS (PL = 0.13). Gene expression in muscle was consistent with an optimized response to Arg supply, whereas Arg appeared to support milk production in the mammary glands through upregulation of genes related to Pro synthesis, AA transport, and protein synthesis.

Résumé

The objective of this study was to determine effects of Arg supply on expression of a select set of genes related to AA metabolism and nutrient partitioning in mammary and longissimus dorsi tissues. Six rumen-cannulated, lactating Holstein cows were used in a replicated 3 × 3 Latin square design with 14-d periods. Treatments were continuous abomasal infusion that supplied 0 (ARGx0), 49.2 (ARGx1), and 98.4 (ARGx2) g/d Arg in an otherwise complete AA mixture at 900 g/d: ARGx1 treatment profiled the rumen microbial AA and met MP
requirements. Tissue samples collected by biopsy on d 14 were analyzed by RT-qPCR relative to stably expressed genes for each tissue. The Arg dose effects were tested using mixed model ANOVA and polynomial
contrasts (L = linear; Q = quadratic). Arg infusion increased mammary mRNA expression of genes involved in proline (Pro) synthesis (OAT (PL = 0.04; PQ = 0.06), PYCR1 (PL = 0.01)) and tended to decrease PYCR1
in muscle (PL = 0.13; PQ = 0.06). Other Arg metabolism genes (ASL, ASS1, ARG2) were decreased in ARGx1 in muscle (PQ < 0.04). Arg infusion decreased AA transporter SLC38A9, but increased SLC7A1, SLC7A5, and SLC7A8, mTORC1 regulators CASTOR1 and LAMTOR4, and ribosomal RNA18S1 in mammary tissue (PL < 0.05) but not in muscle (PL ≥ 0.16), indicating mammary-specific upregulation of protein synthesis. Of the vascular function genes, Arg supply increased mammary NOS3 (PQ = 0.08), FLT1 (PL = 0.05; PQ = 0.01), KDR (PQ = 0.11), and TEK (PL = 0.13; PQ = 0.12), whereas muscle exhibited a decrease for BDKRB2 (PL < 0.01; PQ < 0.01), TEK (PQ = 0.03), ANGPT2 (PQ = 0.11), and VEGFA (PQ = 0.11). The transcription factor response to Arg was different between tissues. In mammary, Arg supply increased ATF4 (PL = 0.03), whereas ARGx1 tended to increase ATF6 (PQ = 0.07), and decreased FOS (PQ = 0.05). In muscle, ARGx1 decreased ATF6 (PQ = 0.02), but increased JUN (PL < 0.01) and FOS (PL = 0.13). Gene expression in muscle was consistent with an optimized response to Arg supply, whereas Arg appeared to support milk production in the mammary glands through upregulation of genes related to Pro synthesis, AA transport, and protein synthesis.

Date de publication

2022-06-19

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