HdeA has been shown to prevent acid-induced aggregation of proteins. With a mass of only 9.7 kDa, HdeA is one of the smallest chaperones known. Unlike other molecular chaperones, which are typically complex, multimeric ATP-dependent machines, HdeA is known to undergo an acid-induced dimer to monomer transition and functions at low pH as a disordered monomer without the need for energy factors. Thus, HdeA must possess features that allow it to bind substrates and regulate substrate affinity in a small and energy-independent package. To understand better how HdeA accomplishes this, we studied the conformational changes that accompany a shift to low pH and substrate binding. We find that the acid-induced partial unfolding and monomerization that lead to HdeA activation occur very rapidly (k >3.5 s ؊1 ). Activation exposes the hydrophobic dimer interface, which we found to be critical for substrate binding. We show by intramolecular FRET that the partially unfolded character of active HdeA allows the chaperone to adopt different conformations as required for the recognition and high-affinity binding of different substrate proteins. These efficient adaptations help to explain how a very small protein is rapidly activated and can bind a broad range of substrate proteins in a purely pH-regulated manner.HdeA ͉ periplasm ͉ posttranslational regulation

Mesenchymal stromal cells (MSCs) are rare progenitor cells that can be isolated from various tissues. They exhibit multilineage differentiation potential, support regenerative processes, and interact with various immune cells. Therefore, MSCs represent a promising tool for regenerative medicine. However, source-dependent and donor-dependent differences of MSC properties, including implications on their clinical application are still largely unknown. We evaluated MSCs derived from perinatal tissues umbilical cord (UC) and amniotic membrane (AM) in comparison to adult MSCs from bone marrow (BM), which were used as gold standard. We found genetic background-independent differences between MSCs from UC and AM. While AM-and UC-MSCs were closer to each other than to BM-MSCs, they also exhibited differences between each other. AM-MSCs from different donors but not UC-MSCs displayed high interdonor variability. In addition, we show that although all MSCs expressed similar surface markers, MSC populations from UC and AM showed differential profiles of gene expression and paracrine factor secretion to BM-derived MSCs. Notably, pathway analysis of gene expression data revealed intriguing differences between MSCs suggesting that MSCs from UC and AM possess in general a higher potential of immunomodulatory capacity, whereas BM-MSCs showed a higher potential of supporting regenerative processes as exemplified by neuronal differentiation and development. These differences between perinatal and BM-derived MSCs may be relevant for clinical applications.

Mesenchymal stromal cells (MSCs) are promising candidates for cell therapy. Their therapeutic use requires extensive expansion to obtain a sufficiently high number of cells for clinical applications. State-of-the-art expansion systems, that is, primarily culture flask-based systems, are limited regarding scale-up, automation, and reproducibility. To overcome this bottleneck, microcarrier (MC)-based expansion processes have been developed. For the first time, MSCs from the perinatal sources umbilical cord (UC) and amniotic membrane (AM) were expanded on MCs. This study focuses on the comparison of flask- and Cytodex 1 MC-expanded MSCs by evaluating the influence of the expansion process on biological MSC characteristics. Furthermore, we tested the hypothesis to obtain more homogeneous MSC preparations by expanding cells on MCs in controlled large-scale bioreactors. MSCs were extensively characterized determining morphology, cell growth, surface marker expression, and functional properties such as differentiation capacity, secretion of paracrine factors, and gene expression. Based on their gene expression profile MSCs from different donors and sources clearly clustered in distinct groups solely depending on the expansion process-MC or flask culture. MC- and flask-expanded MSCs significantly differed from each other regarding surface markers and both paracrine factors and gene expression profiles. Furthermore, based on gene expression analysis, MC cultivation of MSCs in controlled bioreactor systems resulted in less heterogeneity between cells from different donors. In conclusion, MC-based MSC expansion in controlled bioreactors has the potential to reliably produce MSCs with altered characteristics and functions as compared to flask-expanded MSCs. These findings may be useful for the generation of MSCs with tailored properties for clinical applications.

MicroRNAs (miRs) contribute to different aspects of cardiovascular pathology, among others cardiac hypertrophy and atrial fibrillation. The aim of our study was to evaluate the impact of miR-221/222 on cardiac electrical remodeling. Cardiac miR expression was analyzed in a mouse model with altered electrocardiography parameters and severe heart hypertrophy. Next generation sequencing revealed 14 differentially expressed miRs in hypertrophic hearts, with miR-221 and-222 being the strongest regulated miR-cluster. This increase was restricted to cardiomyocytes and not observed in cardiac fibroblasts. Additionally, we evaluated the change of miR-221/222 in vivo in two models of pharmacologically induced heart hypertrophy (angiotensin II, isoprenaline), thereby demonstrating a stimulus-induced increase in miR-221/222 in vivo by angiotensin II but not by isoprenaline. Whole transcriptome analysis by RNA-seq and qRT-PCR validation revealed an enriched number of downregulated mRNAs coding for proteins located in the T-tubule, which are also predicted targets for miR-221/222. Among those, mRNAs were the L-type Ca 2+ channel subunits as well as potassium channel subunits. We confirmed that both miRs target the 3′-untranslated regions of Cacna1c and Kcnj5. Furthermore, enhanced expression of these miRs reduced L-type Ca 2+ channel and Kcnj5 channel abundance and function, which was analyzed by whole-cell patch clamp recordings or Western blot and flux measurements, respectively. miR-221 and-222 contribute to the regulation of L-type Ca 2+ channels as well as Kcnj5 channels and, therefore, potentially contribute to disturbed cardiac excitation generation and propagation. Future studies will have to evaluate the pathophysiological and clinical relevance of aberrant miR-221/222 expression for electrical remodeling. Keywords Electrical remodeling • Cardiomyocytes • Angiotensin II • Heart hypertrophy Abbreviations ANOVA Analysis of variance AUC Area under the curve AII Angiotensin II Bp Base pair BW Body weight Cacna1C Calcium voltage-gated channel subunit α1 C, L-type Cacnb2 Calcium voltage-gated channel auxiliary subunit β2 Cacna2d1 Voltage-dependent calcium channel subunit α2/δ1 Cav1.2 L-type Ca 2+ channel CCH Carbachol, acetylcholine analog cDNA Complementary DNA CE Carbachol effect CM Cardiomyocyte ddPCR Droplet digital PCR Cellular and Molecular Life Sciences

Background The treatment of canine adrenal insufficiency consists of hormone substitution and requires high owner compliance and intense human–dog interaction. This might affect the quality of life (QoL) of owners and their pets. The aim of the study was to evaluate the impact of hypoadrenocorticism and its treatment on the QoL of dogs and their owners. Methods Owners completed a web‐based survey that contained items concerning signalment, owner QoL, dog QoL and long‐term therapy. Results Three hundred and twenty‐two owners participated. Most owners feared an adrenal crisis. Approximately half of the participants reported that the bond between them and their pet increased after diagnosis. Although many participants felt that their own QoL was not affected by their dog's disease, worries about costs and leaving their dog unsupervised were frequently reported. Half of the study participants increased their dog's glucocorticoid doses when a stressful situation was foreseeable (‘boosting’ of therapy). Some administered hydrocortisone, mostly switched from prednisolone, resulting in a reduction in side effects. Conclusions Special attention should be given to glucocorticoid therapy and owner's QoL. The overall worry of an adrenal crisis might increase caregivers’ burden, reducing their overall QoL. Hydrocortisone might be a safe alternative to prednisolone, but further research is necessary to evaluate its long‐term efficacy and safety in dogs.