The transactivation/transformation-domain associated protein (TRRAP) belongs to the Ataxia-telangiectasia mutated (ATM) super-family and has been identified as a cofactor for c-MYC-mediated oncogenic transformation. TRRAP and its yeast homolog (Tra1p) are components of histone acetyltransferase (HAT) complexes, SAGA (refs. 2,4,5), PCAF (ref. 3) and NuA4 (ref. 6), which are important for the regulation of transcription and cell cycle progression and also have a role in cell viability. Yet the biological function of this molecule and how it controls proliferation are still unclear. Here we show that null mutation of Trrap in mice results in peri-implantation lethality due to a blocked proliferation of blastocysts. We use an inducible Cre-loxP system to show that loss of Trrap blocks cell proliferation because of aberrant mitotic exit accompanied by cytokinesis failure and endoreduplication. Trrap-deficient cells fail to sustain mitotic arrest despite chromosome missegregation and disrupted spindles, and display compromised cdk1 activity. Trrap is therefore essential for early development and required for the mitotic checkpoint and normal cell cycle progression.

We investigated the effects of 1α,25-dihydroxyvitamin D3[1,25(OH)2D3] on paracellular intestinal Ca2+absorption by determination of transepithelial electric resistance (TEER), as a measure of tight-junction ion permeability and bidirectional transepithelial45Ca2+fluxes in confluent Caco-2 cell cultures. The rise of TEER to steady-state levels of ∼2,000 Ω ⋅ cm2 was significantly attenuated by 1,25(OH)2D3(by up to 50%) in a dose-dependent fashion between 10−11 and 10−8 M. Synthetic analogs of 1,25(OH)2D3, namely, 1α,25-dihydroxy-16-ene,23-yne-vitamin D3 and 1α,25-dihydroxy-26,27-hexafluoro-16-ene,23-yne-vitamin D3, exhibited similar biopotency, whereas their genomically inactive 1-deoxy congeners were only marginally effective. Enhancement of transepithelial conductance of Caco-2 cell monolayers by vitamin D was accompanied by a significant increase in bidirectional transepithelial45Ca2+fluxes. Although 1,25(OH)2D3also induced cellular45Ca2+uptake from the apical aspect of Caco-2 cell layers and upregulated the expression of calbindin-9kDa mRNA, no significant contribution of the Ca2+-adenosinetriphosphatase-mediated transcellular pathway to transepithelial Ca2+ transport could be detected. Therefore stimulation of Ca2+fluxes across confluent Caco-2 cells very likely results from a genomic effect of vitamin D sterols on assembly and permeability of tight-junctional complexes.

Digital pathology provides a possibility for computational analysis of histological slides and automatization of routine pathological tasks. Histological slides are very heterogeneous concerning staining, sections’ thickness, and artifacts arising during tissue processing, cutting, staining, and digitization. In this study, we digitally reproduce major types of artifacts. Using six datasets from four different institutions digitized by different scanner systems, we systematically explore artifacts’ influence on the accuracy of the pre-trained, validated, deep learning-based model for prostate cancer detection in histological slides. We provide evidence that any histological artifact dependent on severity can lead to a substantial loss in model performance. Strategies for the prevention of diagnostic model accuracy losses in the context of artifacts are warranted. Stress-testing of diagnostic models using synthetically generated artifacts might be an essential step during clinical validation of deep learning-based algorithms.

In the ovarian adenocarcinoma subline N.I, all-trans retinoic acid (ATRA) induced substantial cell death. This response was elicited only at decreased serum levels. Exposure of N.I cells to increasing concentrations of ATRA was accompanied by a considerable up-regulation of c-myc transcript levels that correlated with the rate of cell killing, which itself was an active process as judged by sustained transcriptional expression. ATRA-triggered rounding and detaching of single cells from the substratum was accompanied by degradation of genomic DNA. We show that the N.I model cell line, which is otherwise highly ATRA-resistant, can undergo an ATRA-triggered suicide program when serum is limited. The accompanying c-myc up-regulation seems to be mediated by retinoic-acid-receptor-independent pathways involving membrane-associated phospholipases instead, because manoalide partly suppressed c-myc induction by ATRA but left constitutive c-myc expression unaffected.