Interactions between BRD4S, LOXL2, and MED1 drive cell cycle transcription in triple‐negative breast cancer

Cell cycle; Gene expression; Triple-negative breast cancerCiclo celular; Expresión génica; Cáncer de mama triple negativoCicle cel·lular; Expressió gènica; Càncer de mama triple negatiuTriple‐negative breast cancer (TNBC) often develops resistance to single‐agent treatment, which can be circumvented using targeted combinatorial approaches. Here, we demonstrate that the simultaneous inhibition of LOXL2 and BRD4 synergistically limits TNBC proliferation in vitro and in vivo. Mechanistically, LOXL2 interacts in the nucleus with the short isoform of BRD4 (BRD4S), MED1, and the cell cycle transcriptional regulator B‐MyB. These interactions sustain the formation of BRD4 and MED1 nuclear transcriptional foci and control cell cycle progression at the gene expression level. The pharmacological co‐inhibition of LOXL2 and BRD4 reduces BRD4 nuclear foci, BRD4‐MED1 colocalization, and the transcription of cell cycle genes, thus suppressing TNBC cell proliferation. Targeting the interaction between BRD4S and LOXL2 could be a starting point for the development of new anticancer strategies for the treatment of TNBC.We thank the CRG genomics unit, the CRG‐UPF flow cytometry unit, and the VHIO mouse facility for their contribution. We thank Pharmaxis for the supply of PXS LOXL2 inhibitors. SS is supported by the Plan Estatal de I + D + I (COMBAT PID2019‐110598GA‐I00), and the ERC Starting Grant (ERC‐StG‐852343‐EPICAMENTE). LP‐R is supported by the Juan de la Cierva‐Formación fellowship (FJC2019‐040598‐I) and Fundación Franscico Cobos fellowship. TVT is supported by Plan Estatal de I + D + I (PID2019‐108008RJ‐I00), AECC (INVES20036TIAN), and a Ramón y Cajal investigator contract (RYC2020‐029098‐I). DC is supported by the la Caixa Foundation PhD fellowship (ID 100010434; fellowship code LCF/BQ/DI19/11730061)

Histone H1 depletion triggers an interferon response in cancer cells via activation of heterochromatic repeats

Histone H1 has seven variants in human somatic cells and contributes to chromatin compaction and transcriptional regulation. Knock-down (KD) of each H1 variant in breast cancer cells results in altered gene expression and proliferation differently in a variant specific manner with H1.2 and H1.4 KDs being most deleterious. Here we show combined depletion of H1.2 and H1.4 has a strong deleterious effect resulting in a strong interferon (IFN) response, as evidenced by an up-regulation of many IFN-stimulated genes (ISGs) not seen in individual nor in other combinations of H1 variant KDs. Although H1 participates to repress ISG promoters, IFN activation upon H1.2 and H1.4 KD is mainly generated through the activation of the IFN response by cytosolic nucleic acid receptors and IFN synthesis, and without changes in histone modifications at induced ISG promoters. H1.2 and H1.4 co-KD also promotes the appearance of accessibility sites genome wide and, particularly, at satellites and other repeats. The IFN response may be triggered by the expression of noncoding RNA generated from heterochromatic repeats or endogenous retroviruses upon H1 KD. In conclusion, redundant H1-mediated silencing of heterochromatin is important to maintain cell homeostasis and to avoid an unspecific IFN response

Chromatin reorganization during epithelial-to-mesenchymal transition : a role for euchromatin lamin B1 domains

Les làmines nuclears (A/C i B) són els majors constituents de la làmina nuclear (NL). Els estructuralment conservats dominis associats a les làmines (LADs) estan formats per regions genòmiques que contacten amb la NL. Tot i així, les làmines també s’han trobat dins del nucleoplasma però el paper de les làmines nuceloplasmàtiques encara està per definir. En aquesta tesis, hem mapat la localització de la Lamina B1 en tot el genoma de ratolí en una fracció enriquida en eucromatina i hem seguit el seu dinamisme durant la transició epiteli-mesènquima (EMT). La lamina B1 s’associa amb eucromatina activament expressada i oberta, formant dominis d’eucromatina associats a la lamina B1 (eLADs) dinàmics amb una mida mitjana de 0.3Mb. Les dades del Hi-C relacionen els eLADs amb la organització tri-dimensional del genoma de ratolí durant el procés de transició epiteli-mesènquima i correlaciona l’enriquiment de la lamina B1 a les fronteres de dominis d’associació topològics (TADs) amb un increment de la força de les fronteres. Nivells reduïts de lamina B1 alteren el la EMT i comprometen l’adquisició de característiques mesenquimals. Per tant, el genoma de ratolí necessita de dominis plàstics i dinàmics (eLADs) que continguin nivells predeterminats de lamina B1 per tal que es completi la EMT.The nuclear lamins A/C and B are major constituents of the nuclear lamina (NL). Structurally conserved lamina-associated domains (LADs) are formed by genomic regions that contact the NL. However, lamins are also found in the nucleoplasm, where their role is still unknown. In this thesis, we map the genome-wide localization of lamin B1 into an euchromatin-enriched fraction of the mouse genome and follow its dynamics during the epithelial-to-mesenchymal transition (EMT). Lamin B1 associates with actively expressed and open euchromatin, forming dynamic euchromatin laminB1-associated domains (eLADs) with an average size of 0.3 Mb. Hi-C data link eLADs to the three-dimensional (3D) organization of the mouse genome during EMT process and correlate lamin B1 enrichment at topologically associating domain (TAD) borders with increased border strength. Importantly, reduced levels of lamin B1 alter the EMT signature and compromise acquisition of mesenchymal traits. Therefore, the mouse genome requires dynamic and plastic domains (eLADs) that contain predetermined lamin B1 levels in order to undergo EMT

Chromatin reorganization during epithelial-to-mesenchymal transition : a role for euchromatin lamin B1 domains

Les làmines nuclears (A/C i B) són els majors constituents de la làmina nuclear (NL). Els estructuralment conservats dominis associats a les làmines (LADs) estan formats per regions genòmiques que contacten amb la NL. Tot i així, les làmines també s’han trobat dins del nucleoplasma però el paper de les làmines nuceloplasmàtiques encara està per definir. En aquesta tesis, hem mapat la localització de la Lamina B1 en tot el genoma de ratolí en una fracció enriquida en eucromatina i hem seguit el seu dinamisme durant la transició epiteli-mesènquima (EMT). La lamina B1 s’associa amb eucromatina activament expressada i oberta, formant dominis d’eucromatina associats a la lamina B1 (eLADs) dinàmics amb una mida mitjana de 0.3Mb. Les dades del Hi-C relacionen els eLADs amb la organització tri-dimensional del genoma de ratolí durant el procés de transició epiteli-mesènquima i correlaciona l’enriquiment de la lamina B1 a les fronteres de dominis d’associació topològics (TADs) amb un increment de la força de les fronteres. Nivells reduïts de lamina B1 alteren el la EMT i comprometen l’adquisició de característiques mesenquimals. Per tant, el genoma de ratolí necessita de dominis plàstics i dinàmics (eLADs) que continguin nivells predeterminats de lamina B1 per tal que es completi la EMT.The nuclear lamins A/C and B are major constituents of the nuclear lamina (NL). Structurally conserved lamina-associated domains (LADs) are formed by genomic regions that contact the NL. However, lamins are also found in the nucleoplasm, where their role is still unknown. In this thesis, we map the genome-wide localization of lamin B1 into an euchromatin-enriched fraction of the mouse genome and follow its dynamics during the epithelial-to-mesenchymal transition (EMT). Lamin B1 associates with actively expressed and open euchromatin, forming dynamic euchromatin laminB1-associated domains (eLADs) with an average size of 0.3 Mb. Hi-C data link eLADs to the three-dimensional (3D) organization of the mouse genome during EMT process and correlate lamin B1 enrichment at topologically associating domain (TAD) borders with increased border strength. Importantly, reduced levels of lamin B1 alter the EMT signature and compromise acquisition of mesenchymal traits. Therefore, the mouse genome requires dynamic and plastic domains (eLADs) that contain predetermined lamin B1 levels in order to undergo EMT

Els teus ulls t'enganyen?

Treball de recerca realitzat per alumnes d’ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l’any 2008. Per què cada persona interpreta d’una manera diferent una il•lusió òptica? Quins són els factors que afecten a aquesta interpretació diferent de la realitat? S’analitzen els conceptes de percepció i il•lusió òptica mitjançant una recerca bibliogràfica. Posteriorment s’ha investigat per esbrinar els possibles factors que distorsionen la percepció. Algunes limitacions, com ara el temps i els recursos necessaris només han permés centrar-se en quatre factors: la miopia, l’astigmatisme, l’edat i el sexe. La recerca que s’ha dut a terme consisteix en la realització d’unes enquestes i la posterior extracció de les conclusions a partir d’aquestes mitjançant un programa estadístic. Es conclou que els defectes visuals i l’edat són factors importants que alteren la percepció visual; els factors socioculturals afecten en part la mateixa percepció, i el sexe no afecta la percepció visual

Lysine-Specific Histone Demethylases Contribute to Cellular Differentiation and Carcinogenesis

Histone modifications regulate chromatin structure, gene transcription, and other nuclear processes. Among the histone modifications, methylation has been considered to be a stable, irreversible process due to the slow turnover of methyl groups in chromatin. However, the discovery of three different classes of lysine-specific demethylases—KDM1, Jumonji domain-containing demethylases, and lysyl oxidase-like 2 protein—has drastically changed this view, suggesting a role for dynamic histone methylation in different biological process. In this review, we describe the different mechanisms that these enzymes use to remove lysine histone methylation and discuss their role during physiological (cell differentiation) and pathological (carcinogenesis) processes

LOXL2 Oxidizes Methylated TAF10 and Controls TFIID-Dependent Genes during Neural Progenitor Differentiation

Protein function is often regulated and controlled by posttranslational modifications, such as oxidation. Although oxidation has been mainly considered to be uncontrolled and nonenzymatic, many enzymatic oxidations occur on enzyme-selected lysine residues; for instance, LOXL2 oxidizes lysines by converting the ε-amino groups into aldehyde groups. Using an unbiased proteomic approach, we have identified methylated TAF10, a member of the TFIID complex, as a LOXL2 substrate. LOXL2 oxidation of TAF10 induces its release from its promoters, leading to a block in TFIID-dependent gene transcription. In embryonic stem cells, this results in the inactivation of the pluripotency genes and loss of the pluripotent capacity. During zebrafish development, the absence of LOXL2 resulted in the aberrant overexpression of the neural progenitor gene Sox2 and impaired neural differentiation. Thus, lysine oxidation of the transcription factor TAF10 is a controlled protein modification and demonstrates a role for protein oxidation in regulating pluripotency genes.This work was supported by grants from Instituto de Salud Carlos III (ISCIII) FIS/FEDER (PI12/01250; CP08/00223), MINECO (SAF2013-48849- C2-1-R), Association for International Cancer Research (AICR), Red Temática de Investigación Cooperativa en Cáncer (RTICC, RD012/0036/005), Fundación Cientıfica de la Asociacion Espanñola contra el Cáncer (AECC), AECC Catalunya, and Fundacio´ La Marato´ TV3. S.P. was a recipient of a Miguel Servet contract (ISCIII/FIS); A.I., J.P.C., L.P.-R., and L.F. are supported by contracts from AICR, Fundacio´ La Marato´ TV3, Fundacio´ FERO, and FI Fellowship from/nGeneralitat de Catalunya, respectivel

LOXL2 Oxidizes Methylated TAF10 and Controls TFIID-Dependent Genes during Neural Progenitor Differentiation.

Protein function is often regulated and controlled by posttranslational modifications, such as oxidation. Although oxidation has been mainly considered to be uncontrolled and nonenzymatic, many enzymatic oxidations occur on enzyme-selected lysine residues; for instance, LOXL2 oxidizes lysines by converting the ε-amino groups into aldehyde groups. Using an unbiased proteomic approach, we have identified methylated TAF10, a member of the TFIID complex, as a LOXL2 substrate. LOXL2 oxidation of TAF10 induces its release from its promoters, leading to a block in TFIID-dependent gene transcription. In embryonic stem cells, this results in the inactivation of the pluripotency genes and loss of the pluripotent capacity. During zebrafish development, the absence of LOXL2 resulted in the aberrant overexpression of the neural progenitor gene Sox2 and impaired neural differentiation. Thus, lysine oxidation of the transcription factor TAF10 is a controlled protein modification and demonstrates a role for protein oxidation in regulating pluripotency genes.This work was supported by grants from Instituto de Salud Carlos III (ISCIII) FIS/FEDER (PI12/01250; CP08/00223), MINECO (SAF2013-48849- C2-1-R), Association for International Cancer Research (AICR), Red Temática de Investigación Cooperativa en Cáncer (RTICC, RD012/0036/005), Fundación Cientıfica de la Asociacion Espanñola contra el Cáncer (AECC), AECC Catalunya, and Fundacio´ La Marato´ TV3. S.P. was a recipient of a Miguel Servet contract (ISCIII/FIS); A.I., J.P.C., L.P.-R., and L.F. are supported by contracts from AICR, Fundacio´ La Marato´ TV3, Fundacio´ FERO, and FI Fellowship from/nGeneralitat de Catalunya, respectivel

LOXL2-mediated H3K4 oxidation reduces chromatin accessibility in triple-negative breast cancer cells

Cromosomes; Marcadors pronòsticsCromosomas; Marcadores de pronósticoChromosomes; Prognostic markersOxidation of H3 at lysine 4 (H3K4ox) by lysyl oxidase-like 2 (LOXL2) generates an H3 modification with an unknown physiological function. We find that LOXL2 and H3K4ox are higher in triple-negative breast cancer (TNBC) cell lines and patient-derived xenografts (PDXs) than those from other breast cancer subtypes. ChIP-seq revealed that H3K4ox is located primarily in heterochromatin, where it is involved in chromatin compaction. Knocking down LOXL2 reduces H3K4ox levels and causes chromatin decompaction, resulting in a sustained activation of the DNA damage response (DDR) and increased susceptibility to anticancer agents. This critical role that LOXL2 and oxidized H3 play in chromatin compaction and DDR suggests that functionally targeting LOXL2 could be a way to sensitize TNBC cells to conventional therapy.This work was supported by grants from Instituto de Salud Carlos III (ISCIII) FIS/FEDER (PI12/01250; CP08/00223; PI16/00253; and CB16/12/00449), MINECO (SAF2013-48849-C2-1-R) to SP, BFU2015-68354 to THS, Breast Cancer Research Foundation (BCRF-17-008) to JA, AGL2014-52395-C2-2-R to DA, Worldwide Cancer Research, Red Temática de Investigación Cooperativa en Cáncer (RD012/0036/005), Fundación Científica de la Asociación Española contra el Cáncer, and Fundació La Marató TV3. THS was supported by institutional funding (MINECO) through the Centres of Excellence Severo Ochoa award and the CERCA Programme of the Catalan Government, and SS-B, by a Fundació La Caixa fellowship. We thank La Caixa Foundation and Cellex Foundation for provide research facilities and equipment. GV has received funding from the MINECO (a “Juan de la Cierva Incorporation” fellowship; IJCI-2014-20723). SP was a recipient of a Miguel Servet contract (ISCIII/FIS), and AI, JPC-C, LP-G, and GS-B are supported by contracts from Worldwide Cancer Research, Fundació La Marató TV3, Fundació FERO, and a FI Fellowship from the Generalitat de Catalunya, respectively