The extracellular matrix regulates MaeuCath1a gene expression

• MaeuCath1 is temporally regulated during tammar wallaby lactation.
• The extracellular matrix (ECM) regulates MaeuCath1 gene expression in a lactation phase-dependent manner.
• MaeuCath1 promoter region −709 to −15 has ECM-responsive positive regulatory activity.
• MaeuCath1 promoter region −919 to −710 has repressor activity.

We have previously shown that the gene for MaeuCath1, a cathelicidin secreted in wallaby milk is alternately spliced into two variants, MaeuCath1a and MaeuCath1b which are temporally regulated in order to provide antimicrobial protection to the newborn and stimulate mammary growth, respectively. The current study investigated the extracellular matrix (ECM) for its regulatory role in MaeuCath1 gene expression. Reverse transcription qPCR using RNA isolated from mammary epithelial cells (WallMEC) cultured on ECM showed that ECM regulates MaeuCath1a gene expression in a lactation phase-dependent manner. Luciferase reporter-based assays and in silico analysis of deletion fragments of the 2245 bp sequence upstream of the translation start site identified ECM-dependent positive regulatory activity in the −709 to −15 region and repressor activity in the −919 to −710 region. Electrophoretic Gel Mobility Shift Assays (EMSA) using nuclear extract from ECM-treated WallMEC showed differential band shift in the −839 to −710 region.