The Cornelia de Lange Syndrome-associated factor NIPBL interacts with BRD4 ET domain for transcription control of a common set of genes.

Mutations in NIPBL are the major cause of Cornelia de Lange Syndrome (CdLS). NIPBL is the cohesin-loading factor and has recently been associated with the BET (bromodomains and extra-terminal (ET) domain) proteins BRD2 and BRD4. Related to this, a CdLS-like phenotype has been described associated to BRD4 mutations. Here, we show direct interaction of NIPBL with different BET members in yeast, and selective interaction with BRD4 in cells, being the ET domain involved in the interaction. To understand the relationship between NIPBL and BET proteins, we have performed RNA-Seq expression analysis following depletion of the different proteins. Results indicate that genes regulated by NIPBL largely overlap with those regulated by BRD4 but not with those regulated by BRD2. ChIP-Seq analysis indicates preferential NIPBL occupancy at promoters, and knockdown experiments show mutual stabilization of NIPBL and BRD4 on co-regulated promoters. Moreover, human fibroblasts from CdLS probands with mutations in NIPBL show reduced BRD4 at co-occupied promoters. Functional analysis in vivo, using mutants of Drosophila melanogaster, confirmed the genetic interaction between Nipped-B and fs(1)h, the orthologs of human NIPBL and BRD4, respectively. Thus, we provide evidence for NIPBL and BRD4 cooperation in transcriptional regulation, which should contribute to explain the recently observed CdLS-like phenotype associated with BRD4 mutations.

Lyar-Mediated Recruitment of Brd2 to the Chromatin Attenuates Nanog Downregulation Following Induction of Differentiation.

During development, cellular differentiation programs need tight regulation for proper display of the activity of multiple factors in time and space. Chromatin adaptors of the BET family (Brd2, Brd3, Brd4 and Brdt in vertebrates) are transcription co-regulators tightly associated with the progression of the cell cycle. A key question regarding their function is whether they work as part of the general transcription machinery or, on the contrary, they are precisely recruited to the chromatin through specific transcription factors. Here, we report the selective recruitment of Brd2 to the chromatin by the transcription factor Lyar. We show that Lyar downregulation results in Brd2 dissociation from a number of promoters studied. On the contrary, dissociation of BET proteins from the chromatin has no effect on Lyar occupancy. Under differentiation conditions, the absence of Lyar leads to impaired downregulation of the pluripotency gene Nanog, with concomitant reduction in the upregulation of differentiation markers. Interestingly, following the induction of differentiation, Brd2 depletion exhibits the same effects as expressing a truncated Lyar molecule lacking the Brd2 interacting domain. Both approaches result in stronger Nanog repression, indicating that Lyar-mediated recruitment of Brd2 moderates Nanog downregulation when differentiation is triggered. Moreover, expression of truncated Lyar leads to impaired differentiation and increased apoptosis. Thus, Lyar-mediated recruitment of Brd2 would participate in preserving a proper timing for Nanog silencing ensuring the appropriate establishment of the differentiation program.

The Sumo protease Senp7 is required for proper neuronal differentiation.

Covalent attachment of the Small ubiquitin-like modifier (Sumo) polypeptide to proteins regulates many processes in the eukaryotic cell. In the nervous system, Sumo has been associated with the synapsis and with neurodegenerative diseases. However, its involvement in regulating neuronal differentiation remains largely unknown. Here we show that net Sumo deconjugation is observed during neurogenesis and that Sumo overexpression impairs this process. In an attempt to shed light on the underlying mechanisms, we have analyzed the expression profile of genes coding for components of the sumoylation pathway following induction of neuronal differentiation. Interestingly, we observed strong upregulation of the Senp7 protease at both mRNA and protein levels under differentiation conditions. Sumo proteases, by removing Sumo from targets, are key regulators of sumoylation. Strikingly, loss-of-function analysis demonstrated that Senp7 is required for neuronal differentiation not only in a model cell line, but also in the developing neural tube. Finally, reporter-based analysis of the Senp7 promoter indicated that Senp7 was transiently activated at early stages of neuronal differentiation. Thus, the Sumo protease Senp7 adds to the list of factors involved in vertebrate neurogenesis.

Human iPSC derived disease model of MERTK-associated retinitis pigmentosa.

Retinitis pigmentosa (RP) represents a genetically heterogeneous group of retinal dystrophies affecting mainly the rod photoreceptors and in some instances also the retinal pigment epithelium (RPE) cells of the retina. Clinical symptoms and disease progression leading to moderate to severe loss of vision are well established and despite significant progress in the identification of causative genes, the disease pathology remains unclear. Lack of this understanding has so far hindered development of effective therapies. Here we report successful generation of human induced pluripotent stem cells (iPSC) from skin fibroblasts of a patient harboring a novel Ser331Cysfs*5 mutation in the MERTK gene. The patient was diagnosed with an early onset and severe form of autosomal recessive RP (arRP). Upon differentiation of these iPSC towards RPE, patient-specific RPE cells exhibited defective phagocytosis, a characteristic phenotype of MERTK deficiency observed in human patients and animal models. Thus we have created a faithful cellular model of arRP incorporating the human genetic background which will allow us to investigate in detail the disease mechanism, explore screening of a variety of therapeutic compounds/reagents and design either combined cell and gene- based therapies or independent approaches.

Resultados a medio-largo plazo de pacientes con diabetes tipo 1 remitidos a una consulta monográfica de bombas de insulina / Mid-long term results on the evaluation of type 1 diabetes patients referred to an insulin pump clinic

OBJETIVO: Analizar la evolución a largo plazo de los primeros 69 pacientes con diabetes mellitus tipo 1 remitidos a una consulta monográfica de bombas de insulina durante el periodo 2005-2012, para valorar la iniciación de terapia con infusión subcutánea continua de insulina (ISCI). MATERIAL Y MÉTODOS: Estudio retrospectivo, observacional y unicéntrico de 69 pacientes candidatos a ISCI. Se analizaron los pacientes que no iniciaron ISCI (n = 18) y los que sí lo hicieron (n = 51). Se analizaron las siguientes variables: edad, sexo, duración de la enfermedad, indicación de ISCI, HbA1c, frecuencia de episodios de hipoglucemias severas, cetoacidosis diabética y tasa de retirada de la ISCI. RESULTADOS: El motivo principal para no iniciar ISCI fue el rechazo del paciente (49%), seguido por mejoría de control glucémico tras optimizar tratamiento con múltiples dosis de insulina (MDI) (33%). Las principales indicaciones de ISCI fueron: mal control (49%), seguido de mal control asociado a hipoglucemias no graves (27,5%). La HbA1c previa al inicio de ISCI fue de 8,6 ± 1,5%, con una reducción media de un 1% mantenida durante 5 años (p < 0,001), siendo el descenso superior si la HbA1c basal > 8%. Cinco (10%) pacientes interrumpieron el uso de ISCI tras 1-6 años de la terapia. CONCLUSIÓN: En nuestra práctica clínica uno de cada 4 pacientes remitidos para comenzar ISCI no inician finalmente la terapia. El cambio de MDI a ISCI se asoció con una reducción del 1% de la HbA1c durante los primeros 5 años, siendo mayor en los pacientes con peor control glucémico

OBJECTIVE: To analyse the first 69 type 1 diabetes patients referred to a specialist team between 2005 and 2012 in order to evaluate the indication for continuous subcutaneous insulin infusion (CSII). METHODS: Retrospective, observational, single centre study conducted on 69 adult patients evaluated for CSII. An analysis was made on patients who did not initiate CSII (n = 18) and patients who were treated with CSII (n = 51). Variables included: age, gender, duration of disease, indication for CSII, HbA1c, frequency of severe hypoglycaemia events, episodes of diabetic ketoacidosis, and pump discontinuation. RESULTS: The main reason for not initiating CSII was patient refusal (49%), followed by improving of glycaemic control (33%) after optimising with multiple daily injections (MDI) therapy. The most common CSII indications were: suboptimal glycaemic control (49%), and suboptimal glycaemic control with frequent non-severe hypoglycaemia (27.5%). Baseline HbA1c was 8.6 ± 1.5%, and there was a significant and sustained decrease of 1% over a 5 year period (P < .001), with this reduction being greater in patients with HbA1c > 8%. The use of CSII was stopped by 5 patients (10%) after 1 to 6 years. CONCLUSION: In our clinical practice one in four patients evaluated for CSII did not initiate it. The switch from MDI to CSII was associated with a 1% reduction in HbA1c over 5 years, being greater in patients with poor glycaemic control

Balón intragastrico: revisión de los dispositivos alternativos a los métodos clásicos (Bioenterics) / Intragastric balloon: A review concerning alternative ballons compared to the classical ones (Bioenterics)

Desde la Conferencia de Consenso de Tarpon Spring en 1987, el Balón Intragástrico de Bioenterics se ha impuesto como modelo en el tratamiento de la obesidad con esta técnica. No obstante, a lo largo de los 30 últimos años, y en especial en los 10 últimos, han aparecido nuevos conceptos de balón intragástrico así como modelos alternativos de balón que revisamos en este trabajo (AU)

Since de Tarpon Springs Consensus Conference in 1987, the Bioenterics Intragastric Balloon represents the standard model for obesity treatment with this technique. Nevertheless, over the last 30 years, especially for the last ten years, novel concept of balloons has appeared, as well as new alternative models, which are reviewed in this paper (AU)

[Intragastric balloon: a review concerning alternative balloons compared to the classical ones (Bioenterics)]. / Balón intragastrico: revisión de los dispositivos alternativos a los métodos clásicos (Bioenterics).

Since de Tarpon Springs Consensus Conference in 1987, the Bioenterics Intragastric Balloon represents the standard model for obesity treatment with this technique. Nevertheless, over the last 30 years, especially for the last ten years, novel concept of balloons has appeared, as well as new alternative models, which are reviewed in this paper.

Desde la Conferencia de Consenso de Tarpon Spring en 1987, el Balón Intragástrico de Bioenterics se ha impuesto como modelo en el tratamiento de la obesidad con esta técnica. No obstante, a lo largo de los 30 últimos años, y en especial en los 10 últimos, han aparecido nuevos conceptos de balón intragástrico así como modelos alternativos de balón que revisamos en este trabajo.