title: Temporal profiles of appearance of DNase I hypersensitive sites associated with the ovine beta-lactoglobulin gene differ in sheep and transgenic mice.
abstract: The ovine milk protein beta-lactoglobulin is expressed in a distinct temporal pattern during lactogenesis. This expression pattern is reflected in the temporal profile of appearance of DNase I hypersensitive sites (HS) associated with the beta-lactoglobulin gene in the mammary gland. Specifically, HSIV and HSV are present prior to the first major increase in expression, which occurs at mid-pregnancy, while HSI displays the converse profile, being detected after mid-pregnancy and during lactation. The extent of DNase I digestion at HSIII, encompassing the promoter region, reflects the level of beta-lactoglobulin expression. In transgenic mouse mammary chromatin, beta-lactoglobulin transgenes display the same set of DNase I hypersensitive sites as in sheep mammary chromatin. The temporal profile, however, differs from that seen in sheep: notably, HSIV and HSV are detected during lactation. The fact that beta-lactoglobulin transgenes lacking HSIV and HSV are expressed but display a reduced transcription rate per integrated copy is compatible with a functional role for these regions. This suggests that HSIV and HSV may increase the likelihood of high-level transgene expression.
authors.affiliation: Roslin Institute (Edinburgh), Division of Molecular Biology, Scotland, UK. bruce.whitelaw@bbsrc.ac.uk
authors.forename: C B
authors.initials: CB
authors.lastname: Whitelaw
authors.forename: J
authors.initials: J
authors.lastname: Webster
mesh_terms: D000818:Animals; D003850:Deoxyribonuclease I / Q000378:metabolism; D005260:Female; D017353:Gene Deletion; D015870:Gene Expression; D006801:Humans; D007782:Lactoglobulins / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic / Q000235:genetics; D011247:Pregnancy; D012756:Sheep; D013045:Species Specificity; D014158:Transcription, Genetic; D019076:Transgenes / Q000235:genetics
chemical_list: D007782:Lactoglobulins; D003850:Deoxyribonuclease I