RESUMO
Melanocytes, replenished throughout life by melanocyte stem cells (MSCs), play a critical role in pigmentation and melanoma. Here, we reveal a function for the metastasis-associated phosphatase of regenerating liver 3 (PRL3) in MSC regeneration. We show that PRL3 binds to the RNA helicase DDX21, thereby restricting productive transcription by RNAPII at master transcription factor (MITF)-regulated endolysosomal vesicle genes. In zebrafish, this mechanism controls premature melanoblast expansion and differentiation from MSCs. In melanoma patients, restricted transcription of this endolysosomal vesicle pathway is a hallmark of PRL3-high melanomas. Our work presents the conceptual advance that PRL3-mediated control of transcriptional elongation is a differentiation checkpoint mechanism for activated MSCs and has clinical relevance for the activity of PRL3 in regenerating tissue and cancer.
Assuntos
Diferenciação Celular/genética , RNA Helicases DEAD-box/metabolismo , Melanócitos/citologia , Melanoma/metabolismo , Proteínas de Neoplasias/metabolismo , Proteínas Tirosina Fosfatases/metabolismo , Animais , RNA Helicases DEAD-box/genética , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Melanoma/genética , Fator de Transcrição Associado à Microftalmia/genética , Mutação , Proteínas de Neoplasias/genética , Proteínas Tirosina Fosfatases/genética , Células-Tronco/metabolismo , Peixe-Zebra/metabolismo , Proteínas de Peixe-Zebra/metabolismoRESUMO
Migrating cells have to cross many physical barriers and confined in 3D environments. The surrounding environment promotes mechano- and biological signals that orchestrate cellular changes, such as cytoskeletal and adhesion rearrangements and proteolytic digestion. Recent studies provide new insights into how the nucleus must alter its shape, localization and mechanical properties in order to promote nuclear deformability, chromatin compaction and gene reprogramming. It is known that the chromatin structure contributes directly to genomic and non-genomic functions, such as gene transcription and the physical properties of the nucleus. Here, we appraise paradigms and novel insights regarding the functional role of chromatin during nuclear deformation. In so doing, we review how constraint and mechanical conditions influence the structure, localization and chromatin decompaction. Finally, we highlight the emerging roles of mechanogenomics and the molecular basis of nucleoskeletal components, which open unexplored territory to understand how cells regulate their chromatin and modify the nucleus.
Assuntos
Núcleo Celular/genética , Núcleo Celular/metabolismo , Epigênese Genética/genética , HumanosRESUMO
Cell migration through extracellular matrices requires nuclear deformation, which depends on nuclear stiffness. In turn, chromatin structure contributes to nuclear stiffness, but the mechanosensing pathways regulating chromatin during cell migration remain unclear. Here, we demonstrate that WD repeat domain 5 (WDR5), an essential component of H3K4 methyltransferase complexes, regulates cell polarity, nuclear deformability, and migration of lymphocytes in vitro and in vivo, independent of transcriptional activity, suggesting nongenomic functions for WDR5. Similarly, depletion of RbBP5 (another H3K4 methyltransferase subunit) promotes similar defects. We reveal that a 3D environment increases the H3K4 methylation dependent on WDR5 and results in a globally less compacted chromatin conformation. Further, using atomic force microscopy, nuclear particle tracking, and nuclear swelling experiments, we detect changes in nuclear mechanics that accompany the epigenetic changes induced in 3D conditions. Indeed, nuclei from cells in 3D environments were softer, and thereby more deformable, compared with cells in suspension or cultured in 2D conditions, again dependent on WDR5. Dissecting the underlying mechanism, we determined that actomyosin contractility, through the phosphorylation of myosin by MLCK (myosin light chain kinase), controls the interaction of WDR5 with other components of the methyltransferase complex, which in turn up-regulates H3K4 methylation activation in 3D conditions. Taken together, our findings reveal a nongenomic function for WDR5 in regulating H3K4 methylation induced by 3D environments, physical properties of the nucleus, cell polarity, and cell migratory capacity.
Assuntos
Movimento Celular , Polaridade Celular , Cromatina/metabolismo , Epigênese Genética , Histona-Lisina N-Metiltransferase/metabolismo , Proteínas Nucleares/metabolismo , Cromatina/genética , Cromatina/ultraestrutura , Proteínas de Ligação a DNA , Histona-Lisina N-Metiltransferase/química , Histona-Lisina N-Metiltransferase/genética , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Células Jurkat , Microscopia de Força Atômica , Quinase de Cadeia Leve de Miosina/genética , Quinase de Cadeia Leve de Miosina/metabolismo , Proteínas Nucleares/química , Proteínas Nucleares/genéticaRESUMO
Aberrant WNT signaling drives colorectal cancer (CRC). Here, we identify TIAM1 as a critical antagonist of CRC progression through inhibiting TAZ and YAP, effectors of WNT signaling. We demonstrate that TIAM1 shuttles between the cytoplasm and nucleus antagonizing TAZ/YAP by distinct mechanisms in the two compartments. In the cytoplasm, TIAM1 localizes to the destruction complex and promotes TAZ degradation by enhancing its interaction with ßTrCP. Nuclear TIAM1 suppresses TAZ/YAP interaction with TEADs, inhibiting expression of TAZ/YAP target genes implicated in epithelial-mesenchymal transition, cell migration, and invasion, and consequently suppresses CRC cell migration and invasion. Importantly, high nuclear TIAM1 in clinical specimens associates with increased CRC patient survival. Together, our findings suggest that in CRC TIAM1 suppresses tumor progression by regulating YAP/TAZ activity.