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The microstructure of laminin-111 compensates for dystroglycan loss in mammary epithelial cells in downstream expression of milk proteins.

Biomaterials (2019-07-22)
A J Kent, N Mayer, J L Inman, C Hochman-Mendez, M J Bissell, C Robertson
ABSTRACT

Laminin-111 (Ln-1), an extracellular matrix (ECM) glycoprotein found in the basement membrane of mammary gland epithelia, is essential for lactation. In mammary epithelial cells (MECs), dystroglycan (Dg) is believed to be necessary for polymerization of laminin-111 into networks., thus we asked whether correct polymerization could compensate for Dg loss. Artificially polymerized laminin-111 and the laminin-glycoprotein mix Matrigel, both formed branching, spread networks with fractal dimensions from 1.7 to 1.8, whereas laminin-111 in neutral buffers formed small aggregates without fractal properties (a fractal dimension of 2). In Dg knockout cells, either polymerized laminin-111 or Matrigel readily attached to the cell surface, whereas aggregated laminin-111 did not. In contrast, polymerized and aggregated laminin-111 bound similarly to Dg knock-ins. Both polymerized laminin-111 and Matrigel promoted cell rounding, clustering, formation of tight junctions, and expression of milk proteins, whereas aggregated Ln-1 did not attach to cells or promote functional differentiation. These findings support that the microstructure of Ln-1 networks in the basement membrane regulates mammary epithelial cell function.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Hydrocortisone, BioReagent, suitable for cell culture
Sigma-Aldrich
Anti-Laminin antibody produced in rabbit, 0.5 mg/mL, affinity isolated antibody, buffered aqueous solution
Sigma-Aldrich
Phosphatase Inhibitor Cocktail 1, DMSO solution