title: The extracellular matrix locally regulates asynchronous concurrent lactation in tammar wallaby (Macropus eugenii).
abstract: Asynchronous concurrent lactation (ACL) is an extreme lactation strategy in macropod marsupials including the tammar wallaby, that may hold the key to understanding local control of mammary epithelial cell function. Marsupials have a short gestation and a long lactation consisting of three phases; P2A, P2B and P3, representing early, mid and late lactation respectively and characterised by profound changes in milk composition. A lactating tammar is able to concurrently produce phase 2A and 3 milk from adjacent glands in order to feed a young newborn and an older sibling at heel. Physiological effectors of ACL remain unknown and in this study the extracellular matrix (ECM) is investigated for its role in switching mammary phenotypes between phases of tammar wallaby lactation. Using the level of expression of the genes for the phase specific markers tELP, tWAP, and tLLP-B representing phases 2A, 2B and 3 respectively we show for the first time that tammar wallaby mammary epithelial cells (WallMECs) extracted from P2B acquire P3 phenotype when cultured on P3 ECM. Similarly P2A cells acquire P2B phenotype when cultured on P2B ECM. We further demonstrate that changes in phase phenotype correlate with phase-specific changes in ECM composition. This study shows that progressive changes in ECM composition in individual mammary glands provide a local regulatory mechanism for milk protein gene expression thereby enabling the mammary glands to lactate independently.
authors.affiliation: Centre for Biotechnology, Chemistry and Systems Biology, BioDeakin, Deakin University, 75 Pigdons Rd., 3217 VIC, Australia. stephenw@deakin.edu.au
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Wanyonyi
authors.forename: Christophe
authors.initials: C
authors.lastname: Lefevre
authors.forename: Julie A
authors.initials: JA
authors.lastname: Sharp
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Nicholas
mesh_terms: D000367:Age Factors; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism* / Q000648:ultrastructure; D005109:Extracellular Matrix / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D005786:Gene Expression Regulation; D005838:Genotype; D007774:Lactation / Q000235:genetics* / Q000378:metabolism; D007614:Macropodidae / Q000235:genetics* / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000378:metabolism* / Q000648:ultrastructure; D008894:Milk Proteins / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D011480:Protease Inhibitors / Q000378:metabolism; D015398:Signal Transduction; D000067816:Whey Proteins
chemical_list: D015415:Biomarkers; D002352:Carrier Proteins; D008894:Milk Proteins; D011480:Protease Inhibitors; D000067816:Whey Proteins
keywords: Extracellular matrix; Lactation; Mammary epithelial cells; Milk protein genes; Neonatal development