Vol.:(0123456789) 1 3 Molecular Biology Reports https://doi.org/10.1007/s11033-020-05787-8 SHORT COMMUNICATION Diferent miRNA contents between mammary epithelial cells and milk fat globules: a random or a targeted process? Karol Pawlowski 1,2  · Daiane Lago‑Novais 1,3  · Claudia Bevilacqua 4,5  · Lenha Mobuchon 1,4  · Nicolas Crapart 4,5,6  · Yannick Faulconnier 1  · Céline Boby 1  · Gleidson Carvalho 3  · Patrice Martin 4  · Christine Leroux 1 Received: 24 June 2020 / Accepted: 28 August 2020 © Springer Nature B.V. 2020 Abstract MicroRNAs (miRNAs) are small noncoding RNAs present in milk-derived extracellular vesicles and milk fat globules (MFG). Nucleic acid content between the lactating mammary tissue (MT) and MFG are quite similar but discrepancies exist in their miRNA content. Our objective was to identify the origin of these discrepancies, and to evaluate the existence of a possible mechanism sorting miRNAs that will or will not be exported from the mammary epithelial cells (MECs) in bovine MFG. miR-125b-5p, miR-126-3p, miR-141-3p, and miR-204-5p, chosen on the basis of their abundance in the MT, were quantifed using RT-qPCR in lactating cow MT, MFG, and laser capture-microdissected MECs. Two miRNAs (miR- 125b-5p and miR-141-3p) were detected in the MT as well as in MFG and MECs. miR-204-5p was detected only in the MT, suggesting that it is very likely expressed in a cell type other than MECs. miR-126-3p was detected both in the MT and in MECs but not in MFG, suggesting a targeting mechanism for miRNAs in MECs. These results highlights diferences in miRNA content between MECs and MFG may be due to a possibly not random mechanism for loading MFG with miRNA cargos that could involve a variable distribution in MECs or a sorting mechanism. Keywords MicroRNA · Milk fat · Mammary epithelial cells · Lactating cow · Mammary gland Abbreviations Ct Threshold cycle EV Extracellular vesicle MT Mammary tissue MFG Milk fat MEC Mammary epithelial cell miRNA MicroRNAs nt Nucleotides Introduction MicroRNAs (miRNAs) are small non-coding RNAs (~ 22 nucleotides) that are competent to target mRNAs by base pairing to direct their posttranscriptional repression [1]. miRNAs control various biological processes and are thought to regulate at least 60% of genes at the post-tran- scriptional level [1, 2]. miRNAs that are synthesized in dif- ferent cells or tissues have been detected in several biologi- cal fuids, such as blood, milk, and urine, and described as circulating miRNAs [3]. They are free or carried in extracel- lular vesicles (EVs). EVs, defned as lipid bilayer-enclosed extracellular structures, are a heterogeneous family of Karol Pawlowski and Daiane Lago-Novais have contributed equally to this work. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11033-020-05787-8) contains supplementary material, which is available to authorized users. * Christine Leroux christine.leroux@inrae.fr 1 UMR1213 Herbivores, INRAE, Université Clermont- Auvergne, VetAgro Sup, 63122 Saint Genès Champanelle, France 2 Department of Pathology and Veterinary Diagnostics, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Warsaw, Poland 3 Programa de Pós Graduação em Zootecnia, Universidade Federal da Bahia (UFBA), Av. Adhemar de Barros 500, CEP 40170-110, Salvador, BA, Brazil 4 UMR1313 Génétique Animale et Biologie Intégrative, AgroParisTech, Université Paris-Saclay, INRAE, 78350 Jouy-en-Josas, France 5 Plateforme @BRIDGE, INRAE, Domaine de Vilvert, 78350 Jouy-en-Josas, France 6 Excilone, 78990 Elancourt, France