Hierarchical reactivation of transcription during mitosis-to-G1 transition by Brn2 and Ascl1 in neural stem cells.

During mitosis, chromatin condensation is accompanied by a global arrest of transcription. Recent studies suggest transcriptional reactivation upon mitotic exit occurs in temporally coordinated waves, but the underlying regulatory principles have yet to be elucidated. In particular, the contribution of sequence-specific transcription factors (TFs) remains poorly understood. Here we report that Brn2, an important regulator of neural stem cell identity, associates with condensed chromatin throughout cell division, as assessed by live-cell imaging of proliferating neural stem cells. In contrast, the neuronal fate determinant Ascl1 dissociates from mitotic chromosomes. ChIP-seq analysis reveals that Brn2 mitotic chromosome binding does not result in sequence-specific interactions prior to mitotic exit, relying mostly on electrostatic forces. Nevertheless, surveying active transcription using single-molecule RNA-FISH against immature transcripts reveals differential reactivation kinetics for key targets of Brn2 and Ascl1, with transcription onset detected in early (anaphase) versus late (early G1) phases, respectively. Moreover, by using a mitotic-specific dominant-negative approach, we show that competing with Brn2 binding during mitotic exit reduces the transcription of its target gene Nestin Our study shows an important role for differential binding of TFs to mitotic chromosomes, governed by their electrostatic properties, in defining the temporal order of transcriptional reactivation during mitosis-to-G1 transition.

Zeb1 potentiates genome-wide gene transcription with Lef1 to promote glioblastoma cell invasion.

Glioblastoma is the most common and aggressive brain tumor, with a subpopulation of stem-like cells thought to mediate its recurring behavior and therapeutic resistance. The epithelial-mesenchymal transition (EMT) inducing factor Zeb1 was linked to tumor initiation, invasion, and resistance to therapy in glioblastoma, but how Zeb1 functions at molecular level and what genes it regulates remain poorly understood. Contrary to the common view that EMT factors act as transcriptional repressors, here we show that genome-wide binding of Zeb1 associates with both activation and repression of gene expression in glioblastoma stem-like cells. Transcriptional repression requires direct DNA binding of Zeb1, while indirect recruitment to regulatory regions by the Wnt pathway effector Lef1 results in gene activation, independently of Wnt signaling. Amongst glioblastoma genes activated by Zeb1 are predicted mediators of tumor cell migration and invasion, including the guanine nucleotide exchange factor Prex1, whose elevated expression is predictive of shorter glioblastoma patient survival. Prex1 promotes invasiveness of glioblastoma cells in vivo highlighting the importance of Zeb1/Lef1 gene regulatory mechanisms in gliomagenesis.

Vulvar Hailey-Hailey disease treated with low-dose naltrexone: case report and literature review.

PURPOSE: To report a case of vulvar familial benign pemphigus, or Hailey-Hailey disease, treated successfully with low-dose naltrexone and to review the current literature. METHODS: We report a case of a 71-year-old white woman with vulvar Hailey-Hailey disease recalcitrant to topical corticosteroids. After treatment with low-dose naltrexone, 3 mg nightly was initiated, the lesions began to heal and 5 months later her skin showed no lesions. A literature review on the use of low-dose naltrexone for Hailey-Hailey disease was performed. We searched the PubMed/MEDLINE databases for previous case reports using the key words ''Pemphigus, Benign Familial'' and ''naltrexone". RESULTS: We found 35 more cases of Hailey-Hailey disease treated with naltrexone, showing promising results, reported until January 2020, with no major adverse effects. CONCLUSION: Low-dose naltrexone may represent a cost-effective and successful treatment modality in nongeneralized Hailey-Hailey disease without serious adverse effects. Future prospective studies are needed to investigate this interesting therapeutic option.

Exuberant connubial allergic contact dermatitis from diphenhydramine.

Connubial or consort allergic contact dermatitis occurs when the agent causing the dermatitis has not been used by the patient but by his partner or other cohabitants or proxy. Most cases are due to fragrances, cosmetics or topical nonsteroidal anti-inflammatory agents. We report a case of a connubial dermatitis caused by topical diphenhydramine in a woman who applied the cream on her husband's back.

Multinucleate cell angiohistiocytoma: a new case report with dermoscopy.

Multinucleate cell angiohistiocytoma (MCA) is a benign fibrohistiocytic and vascular proliferation usually located on the extremities. It may be underdiagnosed owing to lack of recognition by clinicians and pathologists. We report a 48-year-old man with asymptomatic grouped reddish papules on the dorsum of his right hand for 8 years. Histopathological and immunohistochemical examinations revealed features of MCA with a fibrohistiocytic cell infiltrate in the dermis and multinucleate cells in the stroma. Recently, the dermoscopy aspects of MCA have been described. We add another observation of this useful tool and correlate it with clinical evolution.

Merkel cell carcinoma: a review and update on aetiopathogenesis, diagnosis and treatment approaches.

Merkel cell carcinoma (MCC) or primary cutaneous neuroendocrine carcinoma is a relatively uncommon form of skin cancer. It is an aggressive neoplasm with high tendency for local recurrence and lymph node and distant metastasis, whose incidence has been rising in the last 2 decades.A novel polyomavirus (MCPyV) has been found in a significant proportion of MCCs, and this finding significantly contributed to the understanding of its pathogenesis.It is fairly consensual at the current state of know-ledge that appropriate staging, including sentinel lymph node biopsy, is very important in order to plan adequate treatment. Treatment includes aggressive surgery of the primary tumour and lymph node basin, commonly combined with adjuvant radiotherapy. Chemotherapy is usually reserved for distant metastasis.In the present article, the authors review the current knowledge about MCC with special emphasis on the new pathogenetic findings and current recommendations regarding management.

Verruciform xanthoma: report of two cases.

Verruciform xanthoma (VX) is an uncommon benign condition of unknown etiology, which frequently affects the oral mucosa in adults. Other less common locations include the anogenital region and the skin. VX typically presents as an asymptomatic plaque showing a verrucous appearance. Histological examination is essential for the diagnosis and shows verrucous hyperplasia of the epidermis and xanthoma cells limited to the dermal papillae. We present herein two cases of VX and discuss the histopathological findings and possible correlation with a postulated etio-pathogenesis.

Targeting the hemangioblast with a novel cell type-specific enhancer.

BACKGROUND: Hemangioblasts are known as the common precursors for primitive hematopoietic and endothelial lineages. Their existence has been supported mainly by the observation that both cell types develop in close proximity and by in vitro differentiation and genetic studies. However, more compelling evidence will arise from tracking their cell fates using a lineage-specific marker. RESULTS: We report the identification of a hemangioblast-specific enhancer (Hb) located in the cis-regulatory region of chick Cerberus gene (cCer) that is able to direct the expression of enhanced green fluorescent protein (eGFP) to the precursors of yolk sac blood and endothelial cells in electroporated chick embryos. Moreover, we present the Hb-eGFP reporter as a powerful live imaging tool for visualizing hemangioblast cell fate and blood island morphogenesis. CONCLUSIONS: We hereby introduce the Hb enhancer as a valuable resource for genetically targeting the hemangioblast population as well as for studying the dynamics of vascular and blood cell development.

Identification of Novel Hemangioblast Genes in the Early Chick Embryo.

During early vertebrate embryogenesis, both hematopoietic and endothelial lineages derive from a common progenitor known as the hemangioblast. Hemangioblasts derive from mesodermal cells that migrate from the posterior primitive streak into the extraembryonic yolk sac. In addition to primitive hematopoietic cells, recent evidence revealed that yolk sac hemangioblasts also give rise to tissue-resident macrophages and to definitive hematopoietic stem/progenitor cells. In our previous work, we used a novel hemangioblast-specific reporter to isolate the population of chick yolk sac hemangioblasts and characterize its gene expression profile using microarrays. Here we report the microarray profile analysis and the identification of upregulated genes not yet described in hemangioblasts. These include the solute carrier transporters SLC15A1 and SCL32A1, the cytoskeletal protein RhoGap6, the serine protease CTSG, the transmembrane receptor MRC1, the transcription factors LHX8, CITED4 and PITX1, and the previously uncharacterized gene DIA1R. Expression analysis by in situ hybridization showed that chick DIA1R is expressed not only in yolk sac hemangioblasts but also in particular intraembryonic populations of hemogenic endothelial cells, suggesting a potential role in the hemangioblast-derived hemogenic lineage. Future research into the function of these newly identified genes may reveal novel important regulators of hemangioblast development.

Do you know this syndrome? Dyspigmentation along the Blaschko lines caused by trisomy 7 mosaicism.

Dyspigmentation along the Blaschko lines is strongly suggestive of a mosaic skin disorder. We report a 9-year-old male patient who presented with swirls and streaks of both hypo and hyperpigmentation involving the entire body. Additionally, he had hypertrichosis, musculoskeletal and minor neurodevelopment abnormalities but no intellectual disability. Cultured fibroblast displayed trisomy 7 mosaicism, which can explain this pigmentary phenotype. Widespread dyspigmentation associated with involvement of other organs should prompt systemic examination to detect additional anomalies and genetic evaluation should be considered, even with normal fetal karyotype.

Fixed drug eruption by etoricoxib confirmed by patch test.

Non-steroidal, anti-inflammatory drugs, followed by antibiotics, are the main causes of fixed drug eruption. They provoke one or several round erythematous or bullous lesions that recur in the same place after taking the causative medication. A positive patch test on residual, lesional skin can replace satisfactorily oral reintroduction. We describe the case of a 74-year-old woman with numerous, rounded, erythematous lesions on the trunk and recurrent blistering on the fifth right-hand finger, which developed a few hours after taking etoricoxib. Lesional patch testing with etoricoxib was positive and reproduced the typical pattern of a fixed drug eruption upon histopathology. We emphasize the specific reactivity of the etoricoxib patch test, and the capacity to reproduce the histologic pattern of the reaction.

MyT1 Counteracts the Neural Progenitor Program to Promote Vertebrate Neurogenesis.

The generation of neurons from neural stem cells requires large-scale changes in gene expression that are controlled to a large extent by proneural transcription factors, such as Ascl1. While recent studies have characterized the differentiation genes activated by proneural factors, less is known on the mechanisms that suppress progenitor cell identity. Here, we show that Ascl1 induces the transcription factor MyT1 while promoting neuronal differentiation. We combined functional studies of MyT1 during neurogenesis with the characterization of its transcriptional program. MyT1 binding is associated with repression of gene transcription in neural progenitor cells. It promotes neuronal differentiation by counteracting the inhibitory activity of Notch signaling at multiple levels, targeting the Notch1 receptor and many of its downstream targets. These include regulators of the neural progenitor program, such as Hes1, Sox2, Id3, and Olig1. Thus, Ascl1 suppresses Notch signaling cell-autonomously via MyT1, coupling neuronal differentiation with repression of the progenitor fate.