MicroRNAs (miRNAs) are endogenous non-coding RNAs about ~21 nucleotides in length, and have been shown to function in post-transcriptional gene silencing (PTGS) in plants and animals. miRNAs have been implicated in playing roles in normal development and apoptosis, as well as in carcinogenesis. The roles of miRNAs in PTGS of their target genes still remains unclear as the mechanism can act either by translational silencing of the target mRNA or mRNA degradation. Target genes of miRNAs can usually be detected by homology in the 3’ untranslated region (UTR) of the transcript to the miRNA sequence, however functional evidence of mRNA silencing still needs to be shown experimentally. As part of investigating the roles of miRNAs in normal mammary gland development and carcinogenesis, I have generated a miRNA library from HC11 cells, a normal mouse mammary epithelial cell line. In generating this library, I hope to define the miRNA profile of the normal mammary gland. Due to the limitations of the HC11 cell line, I also intend to generate another miRNA library from primary mouse mammary epithelial cells (MECs). Once these libraries are generated, I can use the miRNA sequences to look for stem-cell specific miRNAs, miRNAs involved specifically in mammary gland development including lactation and involution, and miRNAs that are aberrantly expressed in cancer.

Jaehnig EJ, Heidt AB, Greene SB, Cornelissen I, Black BL.
Increased susceptibility to isoproterenol-induced cardiac hypertrophy and impaired weight gain in mice lacking the histidine-rich calcium-binding protein.
Mol Cell Biol. 2006 Dec;26(24):9315-26.

Anderson JP, Dodou E, Heidt AB, De Val SJ, Jaehnig EJ, Greene SB, Olson EN, Black BL.
HRC is a direct transcriptional target of MEF2 during cardiac, skeletal, and arterial smooth muscle development in vivo.
Mol Cell Biol. 2004 May;24(9):3757-68.

Verzi MP, Anderson JP, Dodou E, Kelly KK, Greene SB, North BJ, Cripps RM, Black BL.
N-twist, an evolutionarily conserved bHLH protein expressed in the developing CNS, functions as a transcriptional inhibitor.
Dev Biol. 2002 Sep 1;249(1):174-90.