title: Gene expression analysis of protein synthesis pathways in bovine mammary epithelial cells purified from milk during lactation and short-term restricted feeding.
abstract: The objective of the study was to investigate selected key regulatory pathways of milk protein biosynthesis in primary bovine mammary epithelial cells (MECs) of dairy cows during the first 155 days of lactation. In addition, cows were exposed to feed restriction for a short period (FR) during different stages of lactation (week 4 and 21 pp) to study adjustment processes of molecular protein biosynthesis to metabolic challenge. Morning milk samples from twenty-four Holstein-Friesian cows were collected throughout the experimental period (n = 10 per animal). MEC from raw milk were purified using an immunomagnetic separation technique and used for real-time quantitative PCR analyses. As was seen in transcript abundances of all major milk proteins, mRNA levels of E74-like factor 5 (ELF5), an enhancer of signal transducer and activator of transcription (STAT) action, concomitantly decreased towards mid-lactation. Expression of ELF5 as well as of all milk protein genes showed a similar increase during FR in early lactation. Occasional changes in expression could be seen in other Janus kinase (JAK)/STAT factors and in mammalian target of rapamycin (mTOR) pathway elements. Amino acid transfer and glucose transporter and the β-casein expression were also partially affected. In conclusion, our findings suggest a pivotal role of the transcription factor ELF5 in milk protein mRNA expression with complementary JAK/STAT and mTOR signalling for the regulation of protein biosynthesis in the bovine mammary gland.
authors: Physiology Weihenstephan, ZIEL, Technische Universitaet Muenchen, Freising, Germany.
authors: T
authors: T
authors: Sigl
authors: H H D
authors: HH
authors: Meyer
authors: S
authors: S
authors: Wiedemann
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D001692:Biological Transport; D002417:Cattle; D004032:Diet / Q000662:veterinary; D004847:Epithelial Cells / Q000378:metabolism*; D005260:Female; D005508:Food Deprivation / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D051246:Glucose Transport Proteins, Facilitative / Q000235:genetics / Q000378:metabolism; D053612:Janus Kinases / Q000235:genetics / Q000378:metabolism; D007774:Lactation / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000166:cytology*; D008892:Milk / Q000737:chemistry / Q000166:cytology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D050791:STAT Transcription Factors / Q000235:genetics / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D000596:Amino Acids; D051246:Glucose Transport Proteins, Facilitative; D012333:RNA, Messenger; D050791:STAT Transcription Factors; D053612:Janus Kinases; D058570:TOR Serine-Threonine Kinases
keywords: JAK/STAT; cell signalling; gene expression; mTOR; primary mammary epithelial cells; transcription factor