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Aberrant telomerase reactivation in differentiated cells represents a major event in oncogenic transformation. Recurrent somatic mutations in the human telomerase reverse transcriptase (TERT) promoter region, predominantly localized to two nucleotide positions, are highly prevalent in many cancer types. Both mutations create novel consensus E26 transformation-specific (ETS) motifs and are associated with increased TERT expression. Here, we perform an unbiased proteome-wide survey of transcription factor binding at TERT promoter mutations in melanoma. We observe ELF1 binding at both mutations in vitro and we show that increased recruitment of GABP is enabled by the spatial architecture of native and novel ETS motifs in the TERT promoter region. We characterize the dynamics of competitive binding between ELF1 and GABP and provide evidence for ELF1 exclusion by transcriptionally active GABP. This study thus provides an important description of proteome-wide, mutation-specific binding at the recurrent, oncogenic TERT promoter mutations., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Somatic mutations in the promoter of the gene for telomerase reverse transcriptase (TERT) are the most common noncoding mutations in cancer. They are thought to activate telomerase, contributing to proliferative immortality, but the molecular events driving TERT activation are largely unknown. We observed in multiple cancer cell lines that mutant TERT promoters exhibit the H3K4me2/3 mark of active chromatin and recruit the GABPA/B1 transcription factor, while the wild-type allele retains the H3K27me3 mark of epigenetic silencing; only the mutant promoters are transcriptionally active. These results suggest how a single-base-pair mutation can cause a dramatic epigenetic switch and monoallelic expression., (© 2015 Stern et al.; Published by Cold Spring Harbor Laboratory Press.)

Background: Calcium binding protein 4 (CABP4), specifically located in photoreceptor synaptic terminals, has been associated with congenital stationary night blindness based on this clinical diagnosis being made for three individuals from two Swiss families with CABP4 mutations; however, the few reported cases limit phenotype-genotype correlation. We expand the number of reported patients with CABP4 mutations and clinically characterise the CABP4-related phenotype., Methods: A retrospective case series of 11 individuals (age 2â 26 years; four consanguineous families) with early-onset retinal dysfunction found to harbour CABP4 mutations after a strategy of homozygosity analysis and/or candidate gene testing., Results: The 11 patients from four families harboured the same homozygous CABP4 mutation (c.81_82insA; p.Pro28Thrfs*4) and shared a common haplotype. All patients had congenital nystagmus, stable low vision, photophobia and a normal or near-normal fundus appearance. None complained of night blindness when specifically questioned. Eight had hyperopic cycloplegic refractions (≥+ 1.00 dioptre). Electroretinography showed an electronegative waveform response to scotopic bright flash, near-normal to subnormal rod function, and delayed and/or decreased cone responses or was non-recordable. Although these and previously reported families with homozygous mutations were labelled with different clinical diagnoses, all had similar clinical features., Conclusion: These typical clinical features, which do not include a symptom of night blindness, suggest CABP4 mutations. The phenotype is best uniformly termed congenital cone-rod synaptic disorder. In Saudi Arabia a founder homozygous c.81_82insA CABP4 mutation is a recurrent cause.

Heparanase-1 (HPR1), an endoglycosidase that specifically degrades heparan sulfate (HS) proteoglycans, is overexpressed in a variety of malignancies. Our present study sought to determine whether oncogene BRAF and RAS mutations lead to increased HPR1 expression. Reverse transcription-polymerase chain reaction analysis revealed that HPR1 gene expression was increased in HEK293 cells transiently transfected with a mutant BRAF or RAS gene. Flow cytometric analysis revealed that B-Raf activation led to loss of the cell surface HS, which could be blocked by two HPR1 inhibitors: heparin and PI-88. Cotransfection of a BRAF or RAS mutant gene with HPR1 promoter-driven luciferase reporters increased luciferase reporter gene expression in HEK293 cells. Knockdown of BRAF expression in a BRAF-mutated KAT-10 tumor cell line led to the suppression of HPR1 gene expression, subsequently leading to increased cell surface HS levels. Truncational and mutational analyses of the HPR1 promoter revealed that the Ets-relevant elements in the HPR1 promoter were critical for BRAF activation-induced HPR1 expression. Luciferase reporter gene expression driven by a four-copy GA binding protein (GABP) binding site was significantly lower in BRAF siRNA-transfected KAT-10 cells than in the control siRNA-transfected cells. We further showed that BRAF knockdown led to suppression of the expression of the GABPβ, an Ets family transcription factor involved in regulating HPR1 promoter activity. Taken together, our study suggests that B-Raf kinase activation plays an important role in regulating HPR1 expression. Increased HPR1 expression may contribute to the aggressive behavior of BRAF-mutated cancer.