Abstract: microRNAs（miRNAs）represent a class of 19-25 nucleotides long,evolutionarily conserved,single-stranded,non-coding RNA molecules which are widely detected in eukaryotic organism. miRNAs play a post-transcriptional regulatory role by inhibiting the expression or translation of target genes. miR-155,an important member of the microRNAs family,has been increasingly studied due to its multifunctional characteristics. It is involved in many biological processes,such as the development and differentiation of hematopoietic cells,the development and differentiation of immune cells,inflammatory reaction,immune response,muscle development and adipose differentiation. miR-155 is highly expressed in many cancer tissues or cell lines,such as liver cancer,lymphoma,breast cancer,pancreatic cancer,lung cancer and so on,and closely related to tumorigenesis,tumor invasion and metastasis. With the continuous deepening of researches,miR-155 is likely to become a new tumor marker and a novel target for tumor gene therapy. miR-155 plays an irreplaceable role in various life processes and plays an indispensable role in the regulation of relevant signalling pathways. It is a typical important multifunctional miRNA. In this paper,we reviewed the research progresses on the major characteristics and relevant function of miR-155,aiming at discussing the important roles that miR-155 plays in the life activities of the organism and providing new ideas and new methods for the treatment of various diseases.

Key words: miR-155, hematopoiesis, inflammatory, immune, tumor, muscle development, adipose differentiation