Fluid shear stress-modulated chromatin accessibility reveals the mechano-dependency of endothelial SMAD1/5-mediated gene transcription

Bone morphogenetic protein (BMP) signaling and fluid shear stress (FSS) mediate complementary functions in vascular homeostasis and disease development. It remains to be shown whether altered chromatin accessibility downstream of BMP and FSS offers a crosstalk level to explain changes in SMAD-dependent transcription. Here, we employed ATAC-seq to analyze arterial endothelial cells stimulated with BMP9 and/or FSS. We found that BMP9-sensitive regions harbor non-palindromic GC-rich SMAD-binding elements (GGCTCC) and 69.7% of these regions become BMP-insensitive in the presence of FSS. While GATA and KLF transcription factor (TF) motifs are unique to BMP9- and FSS-sensitive regions, respectively, SOX motifs are common to both. Finally, we show that both SOX(13/18) and GATA(2/3/6) family members are directly upregulated by SMAD1/5. These findings highlight the mechano-dependency of SMAD-signaling by a sequential mechanism of first elevated pioneer TF expression, allowing subsequent chromatin opening to eventually providing accessibility to novel SMAD binding sites.

Enhancer hijacking at the ARHGAP36 locus is associated with connective tissue to bone transformation

Heterotopic ossification is a disorder caused by abnormal mineralization of soft tissues in which signaling pathways such as BMP, TGFβ and WNT are known key players in driving ectopic bone formation. Identifying novel genes and pathways related to the mineralization process are important steps for future gene therapy in bone disorders. In this study, we detect an inter-chromosomal insertional duplication in a female proband disrupting a topologically associating domain and causing an ultra-rare progressive form of heterotopic ossification. This structural variant lead to enhancer hijacking and misexpression of ARHGAP36 in fibroblasts, validated here by orthogonal in vitro studies. In addition, ARHGAP36 overexpression inhibits TGFβ, and activates hedgehog signaling and genes/proteins related to extracellular matrix production. Our work on the genetic cause of this heterotopic ossification case has revealed that ARHGAP36 plays a role in bone formation and metabolism, outlining first details of this gene contributing to bone-formation and -disease.

AI reveals insights into link between CD33 and cognitive impairment in Alzheimer's Disease

Modeling biological mechanisms is a key for disease understanding and drug-target identification. However, formulating quantitative models in the field of Alzheimer's Disease is challenged by a lack of detailed knowledge of relevant biochemical processes. Additionally, fitting differential equation systems usually requires time resolved data and the possibility to perform intervention experiments, which is difficult in neurological disorders. This work addresses these challenges by employing the recently published Variational Autoencoder Modular Bayesian Networks (VAMBN) method, which we here trained on combined clinical and patient level gene expression data while incorporating a disease focused knowledge graph. Our approach, called iVAMBN, resulted in a quantitative model that allowed us to simulate a down-expression of the putative drug target CD33, including potential impact on cognitive impairment and brain pathophysiology. Experimental validation demonstrated a high overlap of molecular mechanism predicted to be altered by CD33 perturbation with cell line data. Altogether, our modeling approach may help to select promising drug targets.

Bufavirus genotype 3 in Turkish children with severe diarrhoea

Recently a parvovirus called bufavirus (BuV) has been implicated as a causative agent of diarrhoea. To further reveal the epidemiology and genetic characteristics of BuV, this study was performed in Turkish children with diarrhoea. BuV was detected in 1.4% (8/583) of stool samples. All stool samples from healthy children (n = 148) were negative for BuV. Diarrhoea in BuV-positive patients was severe and occurred mainly during the colder months of the year. Complete genome sequences were generated from four BuVs. Only BuV3 was found, which was genetically and phylogenetically similar to Bhutanese BuV3, indicating that BuV3 is prevalent in Asian countries.

[The mental foramen syndrome]

The authors outline an extraordinary rare case of metastatic mandible carcinoma. The examined patient who earlier had a mastectomy due to breast carcinoma showed signs of the foramen mentale syndrome (numbness, pain, swelling) also on the right side after 5 years. The process of the generalized malignant tumour was first indicated by the mandibula metastatic tumour of the foramen mentale syndrome.