Dephosphorylation of tyrosine 393 in argonaute 2 by protein tyrosine phosphatase 1B regulates gene silencing in oncogenic RAS-induced senescence

PTP1B: mediating ROS signaling to silence genes

Numerous studies have shown that normal cells often respond to the activation of oncogenes by undergoing reactive oxygen species-dependent induction of senescence. Here, we discuss our recent publication identifying protein tyrosine phosphatase PTP1B as an important redox-controlled checkpoint for senescence downstream of oncogenic RAS.

Signaling-mediated regulation of MicroRNA processing

miRNAs are important regulatory elements for gene expression that are involved in diverse physiologic and pathologic processes. Canonical miRNA biogenesis consists of a two-step processing, from primary transcripts (pri-miRNA) to precursor miRNAs (pre-miRNA) mediated by Drosha in the nucleus and from pre-miRNAs to mature miRNAs mediated by Dicer in the cytoplasm. Various routes of miRNA maturation that are tightly regulated by signaling cascades and specific to an individual or a subclass of miRNAs have been recently identified. Here, we review the current findings in signaling-mediated miRNA processing as well as their potential clinical relevance in cancer.

Regulatory Roles of miRNAs in Aging

Aging is a biological process characterized by the progressive deterioration of physiological functions that occurs through the accumulation of macromolecular and cellular damage. This phenomenon impairs tissue function and is a risk factor for many disorders including cardiovascular disease, neurodegenerative disorders, and cancer. A recent study has enumerated nine cellular and molecular hallmarks that represent common denominators of aging and together determine the aging phenotype, highlighting the concept of aging plasticity. Among the multiple molecular mechanisms which may contribute to aging modulation, microRNAs (miRNAs) are raising enormous interest due to their ability to affect all the "Hallmarks of Aging." In this chapter, we will focus on the description of the diverse functional roles of geromiRs, the large and growing subgroup of miRNAs implicated in aging. We will also address the molecular mechanisms underlying miRNA function in aging and discuss potential strategies for managing aging and extending longevity based on geromiR modulation.

New pROSpects for PTP1B: micro-managing oncogene-induced senescence

Oncogene-induced senescence (OIS) provides an important, but incompletely understood, barrier to tumorigenesis. In this issue, Yang et al. (2014) surprisingly report that inactivation of PTP1B by reactive oxygen species is essential for OIS, via effects on AGO2 and microRNA maturation.

ROS-dependent signal transduction

Reactive oxygen species (ROS) are no longer viewed as just a toxic by-product of mitochondrial respiration, but are now appreciated for their role in regulating a myriad of cellular signaling pathways. H2O2, a type of ROS, is a signaling molecule that confers target specificity through thiol oxidation. Although redox-dependent signaling has been implicated in numerous cellular processes, the mechanism by which the ROS signal is transmitted to its target protein in the face of highly reactive and abundant antioxidants is not fully understood. In this review of redox-signaling biology, we discuss the possible mechanisms for H2O2-dependent signal transduction.