Stat5 phosphorylation status and DNA-binding activity in the bovine and murine mammary glands

Wheeler, Thomas T.; Broadhurst, Marita; Sadowski, Henry B.; Farr, V. C.; Prosser, Colin G.

doi:10.1016/s0303-7207(01)00481-6

Cited by 38 publications

(33 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the bovine, STAT5 responds to prolactin and other lactogenic growth factors and its activity increases during lactation mostly due to phosphorylation [128,129]. However, in the bovine mammary gland when compared to the rodent, the role of STAT5 in controlling milk protein expression through the Jak2-Stat5 signaling pathway appears to be weak at best [130], highlighting a difference between the bovine and the mouse in protein synthesis regulation. It has been proposed that the transcription factor E74-like factor 5 (ELF5), a co-regulator of the STAT5 signaling and a mammary epithelial specific ELF gene, can compensate for the lack of prolactin signaling in inducing lactation and, particularly, milk protein synthesis in mice [131,132].…”

Section: Regulation Of Milk Protein Expressionmentioning

confidence: 99%

Milk Protein Synthesis in the Lactating Mammary Gland: Insights from Transcriptomics Analyses

Bionaz¹,

Hurley²,

Loor³

2012

Milk Protein

View full text Add to dashboard Cite

Section: Regulation Of Milk Protein Expressionmentioning

confidence: 99%

Milk Protein Synthesis in the Lactating Mammary Gland: Insights from Transcriptomics Analyses

Bionaz¹,

Hurley²,

Loor³

2012

Milk Protein

View full text Add to dashboard Cite

“…This epigenetic mechanism obviously contributes to establish the competence of the promoter for lactation-specific regulation. Indeed, it has previously been postulated that mechanisms other than prolactin-activated STAT5 signalling must contribute to high-level expression of milk genes in the mammary gland of the cow (Wheeler et al 2001). These authors had found that in cattle, but not in the mouse, neither the abundance of STAT5 factors and their mRNAs, nor the binding activity of these factors retrieved from the udders correlate closely with the extent of lactation.…”

Section: The Far Upstream Enhancer Is Functionally Significant In Vivomentioning

confidence: 99%

DNA-remethylation around a STAT5-binding enhancer in the αS1-casein promoter is associated with abrupt shutdown of αS1-casein synthesis during acute mastitis

Vanselow

Yang²,

Herrmann³

et al. 2006

Journal of Molecular Endocrinology

109

114

View full text Add to dashboard Cite

Prolactin stimulates the expression of milk genes during lactation through the activation of STAT5 transcription factors, which subsequently bind to their cognate target sequence on the promoters. Demethylation of 5methylCpG dinucleotides permits the tissue-specific accessibility of transcription factor-binding sites during development, but remethylation has not been shown to contribute to acute suppression of gene expression. We characterize functionally a novel STAT5-binding lactational enhancer in the far upstream promoter (wK10 kbp) of the bovine aS1-casein-encoding gene. This promoter area is hypomethylated in the lactating udder only. Remethylation of this area accompanies an experimentally elicited acute shutdown of casein synthesis in fully lactating cows, whose udder quarters have experimentally been infected with a pathogenic E. coli strain. Within 24 h after infection, the relevant promoter area was remethylated from 10% of the DNA molecules in the uninfected control quarters to w50% in the infected quarters, the typical values for fully lactating and not lactating udders respectively. Increased methylation resulted in tighter chromatin packing. Concomitantly, the aS1-casein mRNA concentration dropped to w50% while the protein synthesis was shut down to w2 . 5% in the infected quarters, alone. The methylation status of the promoter from a not lactationally regulated gene was unaltered, and the distal aS1-casein promoter was not remethylated in udder quarters with subclinical Staphylococcus aureus infections featuring sustained casein synthesis. Hence, infection-related remethylation of the aS1-casein promoter and chromatin remodelling serves as an acute, spatially restricted regulatory mechanism, which might insulate the promoter against the systemically unchanged high levels of circulating prolactin. This provides a rare example for an acute regulatory significance of CpG methylation.

show abstract

“…After 2 h, cells were lysed and Western blot with antibodies against Abl (8E9) or antiphosphotyrosine (4G10) was performed as described previously. 7 Monoclonal antiphospho-STAT5 antibodies were a kind gift from Tom Wheeler (Hamilton, New Zealand), 9 the hybridoma supernatant was diluted 1:200. Polyclonal anti-STAT5 antibodies were purchased from Santa Cruz (Heidelberg, Germany).…”

Section: Western Blot Analysismentioning

confidence: 99%

Phosphorylation of tyrosine 393 in the kinase domain of Bcr-Abl influences the sensitivity towards imatinib in vivo

et al. 2003

View full text Add to dashboard Cite

The Bcr-Abl fusion protein arising through the t(9;22)(q34;q11) reciprocal translocation is the causative agent in chronic myeloid leukemia and a subset of acute lymphocytic leukemia. Imatinib mesylate is a specific inhibitor of the Bcr-Abl kinase and has shown promising results in clinical studies. The structural relation between the Bcr-Abl oncogene and the tyrosine kinase inhibitor imatinib has recently been elucidated by an elegant crystal structure analysis, emphasizing the importance of dephosphorylated tyrosine 393 (Tyr393) in BcrAbl for access of the inhibitor to the kinase domain. By mutating this tyrosine to phenylalanine and thereby mimicking a constitutively dephosphorylated state, we now show that Ba/ F3 cells transformed by this mutant demonstrate an increased sensitivity towards imatinib in vivo. This effect is not due to an impaired kinase activity of Bcr-Abl Y393F, since a synthetic substrate is phosphorylated with similar kinetics. Treatment of Ba/F3 cells transfected with Bcr-Abl wild type with a phosphatase inhibitor diminished the effect of imatinib, but did not influence the growth of Ba/F3 cells transfected with BcrAblY393F. The results support the findings of the crystal structure and indicate that Tyr393 indeed plays a significant role for the sensitivity of Bcr-Abl towards imatinib in vivo. These data implicate the regulation of Tyr393 phosphorylation as a potential mechanism of imatinib resistance. Leukemia (2003) IntroductionThe tyrosine kinase inhibitor imatinib has recently emerged as an important new treatment option in patients with chronic myeloid leukemia (CML) and Philadelphia chromosome-positive (Ph + ) acute lymphocytic leukemias (ALL) carrying the t(9;22) translocation. 1,2 Unfortunately, many patients with advanced CML and nearly all patients with ALL quickly develop resistance to imatinib treatment. [3][4][5] Imatinib has been shown to bind specifically to the nucleotide-binding pocket in the catalytic domain of Bcr-Abl. 6 Tyrosine 393 (Tyr393) is located in the activation loop of the Bcr-Abl kinase domain and has been proposed to stabilize the activation loop in the open formation when phosphorylated, thereby restricting the access of imatinib to the catalytic region and compromising its inhibitory function. Thus, phosphorylation of Tyr393 may function as a switch, regulating accessibility of imatinib to its binding site in the Bcr-Abl protein. Therefore, other molecules that are able to 'flick the switch' may influence imatinib sensitivity in a Bcr-Abl tranformed cell, and overexpression of kinases or downregulation of phosphatases targeting Tyr393 may induce imatinib resistance. As the importance of this amino acid for imatinib binding has been shown in vitro, we aimed at examining the relevance of phosphorylation of Tyr393 in vivo. We demonstrate here that a mutant Bcr-Abl imitating a constitutively dephosphorylated Tyr393 renders Ba/F3 cells more sensitive towards imatinib inhibition. Materials and methods DNA constructs, cells and transfectionsThe mutation of Tyr3...

show abstract

Stat5 phosphorylation status and DNA-binding activity in the bovine and murine mammary glands

Cited by 38 publications

References 29 publications

Milk Protein Synthesis in the Lactating Mammary Gland: Insights from Transcriptomics Analyses

Milk Protein Synthesis in the Lactating Mammary Gland: Insights from Transcriptomics Analyses

DNA-remethylation around a STAT5-binding enhancer in the αS1-casein promoter is associated with abrupt shutdown of αS1-casein synthesis during acute mastitis

Phosphorylation of tyrosine 393 in the kinase domain of Bcr-Abl influences the sensitivity towards imatinib in vivo

Contact Info

Product

Resources

About