Proper cellular functionality and homeostasis are maintained by the convergent integration of various signaling cascades, which enable cells to respond to internal and external changes. The Dbf2-related kinases LATS1 and LATS2 (LATS) have emerged as central regulators of cell fate, by modulating the functions of numerous oncogenic or tumor suppressive effectors, including the canonical Hippo effectors YAP/TAZ, the Aurora mitotic kinase family, estrogen signaling and the tumor suppressive transcription factor p53. While the basic functions of the LATS kinase module are strongly conserved over evolution, the genomic duplication event leading to the emergence of two closely related kinases in higher organisms has increased the complexity of this signaling network. Here, we review the LATS1 and LATS2 intrinsic features as well as their reported cellular activities, emphasizing unique characteristics of each kinase. While differential activities between the two paralogous kinases have been reported, many converge to similar pathways and outcomes. Interestingly, the regulatory networks controlling the mRNA expression pattern of LATS1 and LATS2 differ strongly, and may contribute to the differences in protein binding partners of each kinase and in the subcellular locations in which each kinase exerts its functions.

Degradation of mutant Ndc10 is mediated by the E3 ligase Doa10 at the endoplasmic reticulum/nuclear envelope membrane. An autonomous degradation motif was localized to the C-terminal region of Ndc10. The motif is composed of two indispensable elements: a hydrophobic surface of an amphipathic helix and a loosely structured, hydrophobic C-terminal tail.

Within the tumor microenvironment, cancer cells coexist with noncancerous adjacent cells that constitute the tumor microenvironment and impact tumor growth through diverse mechanisms. In particular, cancer-associated fibroblasts (CAFs) promote tumor progression in multiple ways. Earlier studies have revealed that in normal fibroblasts (NFs), p53 plays a cell nonautonomous tumor-suppressive role to restrict tumor growth. We now wished to investigate the role of p53 in CAFs. Remarkably, we found that the transcriptional program supported by p53 is altered substantially in CAFs relative to NFs. In agreement, the p53-dependent secretome is also altered in CAFs. This transcriptional rewiring renders p53 a significant contributor to the distinct intrinsic features of CAFs, as well as promotes tumor cell migration and invasion in culture. Concordantly, the ability of CAFs to promote tumor growth in mice is greatly compromised by depletion of their endogenous p53. Furthermore, cocultivation of NFs with cancer cells renders their p53-dependent transcriptome partially more similar to that of CAFs. Our findings raise the intriguing possibility that tumor progression may entail a nonmutational conversion ("education") of stromal p53, from tumor suppressive to tumor supportive.

The three p53 family members, p53, p63 and p73, are structurally similar and share many biochemical activities. Yet, along with their common fundamental role in protecting genomic fidelity, each has acquired distinct functions related to diverse cell autonomous and non-autonomous processes. Similar to the p53 family, the Hippo signaling pathway impacts a multitude of cellular processes, spanning from cell cycle and metabolism to development and tumor suppression. The core Hippo module consists of the tumor-suppressive MST-LATS kinases and oncogenic transcriptional co-effectors YAP and TAZ. A wealth of accumulated data suggests a complex and delicate regulatory network connecting the p53 and Hippo pathways, in a highly context-specific manner. This generates multiple layers of interaction, ranging from interdependent and collaborative signaling to apparent antagonistic activity. Furthermore, genetic and epigenetic alterations can disrupt this homeostatic network, paving the way to genomic instability and cancer. This strengthens the need to better understand the nuances that control the molecular function of each component and the cross-talk between the different components. Here, we review interactions between the p53 and Hippo pathways within a subset of physiological contexts, focusing on normal stem cells and development, as well as regulation of apoptosis, senescence and metabolism in transformed cells.

p53 is a pivotal tumor suppressor and a major barrier against cancer. We now report that silencing of the Hippo pathway tumor suppressors LATS1 and LATS2 in nontransformed mammary epithelial cells reduces p53 phosphorylation and increases its association with the p52 NF-κB subunit. Moreover, it partly shifts p53's conformation and transcriptional output toward a state resembling cancer-associated p53 mutants and endows p53 with the ability to promote cell migration. Notably, LATS1 and LATS2 are frequently down-regulated in breast cancer; we propose that such down-regulation might benefit cancer by converting p53 from a tumor suppressor into a tumor facilitator.

DNA methylation is a key regulator of embryonic stem cell (ESC) biology, dynamically changing between naïve, primed, and differentiated states. The p53 tumor suppressor is a pivotal guardian of genomic stability, but its contributions to epigenetic regulation and stem cell biology are less explored. We report that, in naïve mouse ESCs (mESCs), p53 restricts the expression of the de novo DNA methyltransferases Dnmt3a and Dnmt3b while upregulating Tet1 and Tet2, which promote DNA demethylation. The DNA methylation imbalance in p53-deficient (p53 −/− ) mESCs is the result of augmented overall DNA methylation as well as increased methylation landscape heterogeneity. In differentiating p53−/− mESCs, elevated methylation persists, albeit more mildly. Importantly, concomitant with DNA methylation heterogeneity, p53−/− mESCs display increased cellular heterogeneity both in the "naïve" state and upon induced differentiation. This impact of p53 loss on 5-methylcytosine (5mC) heterogeneity was also evident in human ESCs and mouse embryos in vivo. Hence, p53 helps maintain DNA methylation homeostasis and clonal homogeneity, a function that may contribute to its tumor suppressor activity.[Keywords: DNA methylation; p53; stem cells] Supplemental material is available for this article. DNA methylation is a key epigenetic mark that is correlated with the major transitions during embryogenesis and other developmental processes. Differentiation and dedifferentiation of mouse embryonic stem cells (mESCs) provide a model for analyzing the regulation and possible functional roles of DNA methylation in maintaining pluripotency and facilitating differentiation. For example, when mESCs are induced to undergo differentiation, the transcriptional network ensuring pluripotency is silenced, and de novo DNA methylation is observed at promoters of key pluripotency factors (Thiagarajan et al. 2014). Conversely, when serum-maintained mESCs are moved to serum-free conditions with two kinase inhibitors (2i), their developmental potential is enhanced alongside substantial loss of DNA methylation . These transitions recapitulate early embryonic stages (Nichols and Smith 2009;Martin Gonzalez et al. 2016), but the mechanisms modulating DNA methylation remain to be fully characterized. The DNA methylation machinery is crucial for lineage specification, and mice lacking functional DNA methyltransferases (DNMTs) fail to develop properly (Siegfried and Cedar 1997;Smith and Meissner 2013); therefore, more comprehensive elucidation of the regulation of DNA methylation is pivotal to understanding the pluripotent state.In mammals, DNA methylation is governed by three DNMTs: Dnmt3a and Dnmt3b, responsible for setting de novo DNA methylation patterns, and Dnmt1, required primarily for maintenance of such patterns. In addition, TET enzymes (Tet1 and Tet2 in mESCs) facilitate demethylation by catalyzing oxidation of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), which, by sequential oxidation steps, provides the substrate for reversal to unmethylated...

In luminal B tumors LATS2 depletion results in metabolic rewiring whereas LATS1 depletion promotes the expression of basal-like features.

The analysis of cell-free DNA (cfDNA) in plasma represents a rapidly advancing field in medicine, providing information on pathological processes in the body. Blood cfDNA is in the form of nucleosomes, which maintain their tissue-and cancer-specific epigenetic state. We developed EPINUC, a single-molecule multi-parametric assay to comprehensively profile the Epigenetics of Plasma Isolated Nucleosomes, DNA methylation and cancer-specific protein biomarkers. Our system allows high-resolution detection of six active and repressive histone modifications, their ratios and combinatorial patterns, on millions of individual nucleosomes by single-molecule imaging. In addition, it provides sensitive and quantitative data on plasma proteins, including detection of nonsecreted tumor-specific proteins such as mutant p53. Applying this analysis to a cohort of plasma samples detected colorectal cancer at high accuracy and sensitivity, even at early stages. Finally, combining EPINUC with direct single-molecule DNA sequencing revealed the tissue-of-origin of colorectal, pancreatic, lung and breast tumors. EPINUC provides multi-layered clinical-relevant information from limited liquid biopsy material, establishing a novel approach for cancer diagnostics.