PTEN regulates cilia through Dishevelled.

Cilia are hair-like cellular protrusions important in many aspects of eukaryotic biology. For instance, motile cilia enable fluid movement over epithelial surfaces, while primary (sensory) cilia play roles in cellular signalling. The molecular events underlying cilia dynamics, and particularly their disassembly, are not well understood. Phosphatase and tensin homologue (PTEN) is an extensively studied tumour suppressor, thought to primarily act by antagonizing PI3-kinase signalling. Here we demonstrate that PTEN plays an important role in multicilia formation and cilia disassembly by controlling the phosphorylation of Dishevelled (DVL), another ciliogenesis regulator. DVL is a central component of WNT signalling that plays a role during convergent extension movements, which we show here are also regulated by PTEN. Our studies identify a novel protein substrate for PTEN that couples PTEN to regulation of cilia dynamics and WNT signalling, thus advancing our understanding of potential underlying molecular etiologies of PTEN-related pathologies.

Evidence for positive selection on a number of MicroRNA regulatory interactions during recent human evolution.

MicroRNA (miRNA)-mediated gene regulation is of critical functional importance in animals and is thought to be largely constrained during evolution. However, little is known regarding evolutionary changes of the miRNA network and their role in human evolution. Here we show that a number of miRNA binding sites display high levels of population differentiation in humans and thus are likely targets of local adaptation. In a subset we demonstrate that allelic differences modulate miRNA regulation in mammalian cells, including an interaction between miR-155 and TYRP1, an important melanosomal enzyme associated with human pigmentary differences. We identify alternate alleles of TYRP1 that induce or disrupt miR-155 regulation and demonstrate that these alleles are selected with different modes among human populations, causing a strong negative correlation between the frequency of miR-155 regulation of TYRP1 in human populations and their latitude of residence. We propose that local adaptation of microRNA regulation acts as a rheostat to optimize TYRP1 expression in response to differential UV radiation. Our findings illustrate the evolutionary plasticity of the microRNA regulatory network in recent human evolution.