MicroRNAs in autophagy and their emerging roles in crosstalk with apoptosis

Macroautophagy (hereafter referred to as autophagy) is an evolutionarily conserved self-degradative process, which involves the regular turnover of cellular components via sequestering damaged macromolecules and transporting them for lysosomal degradation. In the past few years, the scientific community has produced remarkable advances in our understanding of the genes that are involved in autophagy and of their profound effects on various diseases. Recently, a new class of noncoding RNAs, known as microRNAs (miRNAs), has been demonstrated to play crucial roles in diverse biological processes including development, cell differentiation and apoptosis. Here, we review the current understanding about miRNAs focusing on their involvement in the autophagy process. Intriguingly, several confirmed targets of these autophagy-miRNAs are also important regulators in the crosstalk between autophagy and apoptosis. Furthermore, transcripts involved in autophagy and apoptosis may indirectly modulate each other by competing for common miRNA binding sites. Thus, miRNAs potentially work as molecular switches between these two intimately connected processes and contribute to the cell fate decision.