RESUMO
Cancer cells exhibit modifications in nuclear architecture and transcriptional control. Tumor growth and metastasis are supported by RUNX family transcriptional scaffolding proteins, which mediate the assembly of nuclear-matrix-associated gene-regulatory hubs. We used proteomic analysis to identify RUNX2-dependent protein-protein interactions associated with the nuclear matrix in bone, breast and prostate tumor cell types and found that RUNX2 interacts with three distinct proteins that respond to DNA damage - RUVBL2, INTS3 and BAZ1B. Subnuclear foci containing these proteins change in intensity or number following UV irradiation. Furthermore, RUNX2, INTS3 and BAZ1B form UV-responsive complexes with the serine-139-phosphorylated isoform of H2AX (γH2AX). UV irradiation increases the interaction of BAZ1B with γH2AX and decreases histone H3 lysine 9 acetylation levels, which mark accessible chromatin. RUNX2 depletion prevents the BAZ1B-γH2AX interaction and attenuates loss of H3K9 and H3K56 acetylation. Our data are consistent with a model in which RUNX2 forms functional complexes with BAZ1B, RUVBL2 and INTS3 to mount an integrated response to DNA damage. This proposed cytoprotective function for RUNX2 in cancer cells might clarify its expression in chemotherapy-resistant and/or metastatic tumors.
Assuntos
Proteínas de Transporte/metabolismo , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , DNA Helicases/metabolismo , Reparo do DNA/genética , Proteínas de Ligação a DNA/metabolismo , Fatores de Transcrição/metabolismo , ATPases Associadas a Diversas Atividades Celulares , Acetilação , Neoplasias Ósseas/genética , Neoplasias Ósseas/patologia , Linhagem Celular Tumoral , Subunidade alfa 1 de Fator de Ligação ao Core/genética , Dano ao DNA/genética , Histonas/metabolismo , Humanos , Complexos Multiproteicos/metabolismo , Osteossarcoma/genética , Osteossarcoma/patologia , Fosforilação , Interferência de RNA , RNA Interferente Pequeno , Raios UltravioletaRESUMO
Understanding the mechanisms that sustain pluripotency in human embryonic stem cells (hESCs) is an active area of research that may prove useful in regenerative medicine and will provide fundamental information relevant to development and cancer. hESCs and cancer cells share the unique ability to proliferate indefinitely and rapidly. Because the protein survivin is uniquely overexpressed in virtually all human cancers and in hESCs, we sought to investigate its role in supporting the distinctive capabilities of these cell types. Results presented here suggest that survivin contributes to the maintenance of pluripotency and that post-transcriptional control of survivin isoform expression is selectively regulated by microRNAs. miR-203 has been extensively studied in human tumors, but has not been characterized in hESCs. We show that miR-203 expression and activity is consistent with the expression and subcellular localization of survivin isoforms that in turn modulate expression of the Oct4 and Nanog transcription factors to sustain pluripotency. This study contributes to understanding of the complex regulatory mechanisms that govern whether hESCs proliferate or commit to lineages.
Assuntos
Células-Tronco Embrionárias/fisiologia , Proteínas Inibidoras de Apoptose/metabolismo , MicroRNAs/biossíntese , Células-Tronco Pluripotentes/fisiologia , Diferenciação Celular/genética , Proliferação de Células , Células Cultivadas , Regulação da Expressão Gênica no Desenvolvimento , Regulação Neoplásica da Expressão Gênica , Proteínas de Homeodomínio/biossíntese , Humanos , Proteínas Inibidoras de Apoptose/biossíntese , Proteínas Inibidoras de Apoptose/genética , MicroRNAs/genética , Proteína Homeobox Nanog , Fator 3 de Transcrição de Octâmero/biossíntese , Isoformas de Proteínas/genética , Interferência de RNA , RNA Mensageiro/biossíntese , RNA Mensageiro/metabolismo , RNA Interferente Pequeno , SurvivinaRESUMO
Long suspected, recently recognized, and increasingly studied, non protein-coding RNAs (ncRNAs) are emerging as key drivers of biological control and pathology. Since their discovery in 1993, microRNAs (miRNAs) have been the subject of intense research focus and investigations have revealed striking findings, establishing that these molecules can exert a substantial level of biological control in numerous tissues. More recently, long ncRNAs (lncRNAs), the lesser-studied siblings of miRNA, have been suggested to have a similar robust role in developmental and adult tissue regulation. Mesenchymal stem cells (MSCs) are an important source of multipotent cells for normal and therapeutic tissue repair. Much is known about the critical role of miRNAs in biogenesis and differentiation of MSCs however; recent studies have suggested lncRNAs may play an equally important role in the regulation of these cells. Here we highlight the role of lncRNAs in the regulation of mesenchymal stem cell lineages including adipocytes, chondrocytes, myoblasts, and osteoblasts. In addition, the potential for these noncoding RNAs to be used as biomarkers for disease or therapeutic targets is also discussed.
