BackgroundMany ion channels are preferentially located in caveolae where compartmentalisation/scaffolding with signal transduction components regulates their activity. Channels that are mechanosensitive may be additionally dependent on caveolar control of the mechanical state of the membrane. Here we test which mechanism underlies caveolar-regulation of the mechanosensitive I Cl,swell channel in the adult cardiac myocyte.Methodology/Principal FindingsRat ventricular myocytes were exposed to solution of 0.02 tonicity (T; until lysis), 0.64T for 10–15 min (swelling), and/or methyl-β-cyclodextrin (MBCD; to disrupt caveolae). MBCD and 0.64T swelling reduced the number of caveolae visualised by electron microscopy by 75 and 50% respectively. MBCD stimulated translocation of caveolin 3 from caveolae-enriched buoyant membrane fractions, but both caveolin 1 and 3 remained in buoyant fractions after swelling. I Cl,swell inhibition in control cells decreased time to half-maximal volume (t 0.5,vol; 0.64T), consistent with a role for I Cl,swell in volume regulation. MBCD-treated cells showed reduced time to lysis (0.02T) and t 0.5,vol (0.64T) compared with controls. The negative inotropic response to swelling (an index of I Cl,swell activation) was enhanced by MBCD.Conclusions/SignificanceThese data show that disrupting caveolae removes essential membrane reserves, which speeds swelling in hyposmotic conditions, and thereby promotes activation of I Cl,swell. They illustrate a general principle whereby caveolae as a membrane reserve limit increases in membrane tension during stretch/swelling thereby restricting mechanosensitive channel activation.

The known challenge of underutilization of data and biological material from biorepositories as potential resources for medical research has been the focus of discussion for over a decade. Recently developed guidelines for improved data availability and reusability—entitled FAIR Principles (Findability, Accessibility, Interoperability, and Reusability)—are likely to address only parts of the problem. In this article, we argue that biological material and data should be viewed as a unified resource. This approach would facilitate access to complete provenance information, which is a prerequisite for reproducibility and meaningful integration of the data. A unified view also allows for optimization of long-term storage strategies, as demonstrated in the case of biobanks. We propose an extension of the FAIR Principles to include the following additional components: (1) quality aspects related to research reproducibility and meaningful reuse of the data, (2) incentives to stimulate effective enrichment of data sets and biological material collections and its reuse on all levels, and (3) privacy-respecting approaches for working with the human material and data. These FAIR-Health principles should then be applied to both the biological material and data. We also propose the development of common guidelines for cloud architectures, due to the unprecedented growth of volume and breadth of medical data generation, as well as the associated need to process the data efficiently.

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A calculation grid developed by an international expert group was tested across biobanks in six countries to evaluate costs for collections of various types of biospecimens. The assessment yielded a tool for setting specimen-access prices that were transparently related to biobank costs, and the tool was applied across three models of collaborative partnership.

Cardiac hypertrophy is associated with a dramatic change in the gene expression profile of cardiac myocytes. Many genes important during development of the fetal heart but repressed in the adult tissue are reexpressed, resulting in gross physiological changes that lead to arrhythmias, cardiac failure, and sudden death. One transcription factor thought to be important in repressing the expression of fetal genes in the adult heart is the transcriptional repressor REST (repressor element 1-silencing transcription factor). Although REST has been shown to repress several fetal cardiac genes and inhibition of REST function is sufficient to induce cardiac hypertrophy, the molecular mechanisms employed in this repression are not known. Here we show that continued REST expression prevents increases in the levels of the BNP (Nppb) and ANP (Nppa) genes, encoding brain and atrial natriuretic peptides, in adult rat ventricular myocytes in response to endothelin-1 and that inhibition of REST results in increased expression of these genes in H9c2 cells. Increased expression of Nppb and Nppa correlates with increased histone H4 acetylation and histone H3 lysine 4 methylation of promoter-proximal regions of these genes. Furthermore, using deletions of individual REST repression domains, we show that the combined activities of two domains of REST are required to efficiently repress transcription of the Nppb gene; however, a single repression domain is sufficient to repress the Nppa gene. These data provide some of the first insights into the molecular mechanism that may be important for the changes in gene expression profile seen in cardiac hypertrophy.The repressor element 1-silencing transcription factor (REST) was originally identified as an important transcription factor regulating the expression of neuron-specific genes (12, 53) but has since been shown to be a key transcriptional regulator in heart development (28) and vascular smooth muscle growth (11). Disruption of REST function by expression of a dominant-negative form specifically in the heart results in cardiomyopathy, arrhythmias, and sudden death (28). These effects are thought to result from the reexpression of fetal cardiac genes and have led to the proposition that REST represses the fetal cardiac gene program in the adult heart (28). In vascular smooth muscle, loss of REST has been implicated in neointimal hyperplasia, and inhibition of REST results in increased smooth muscle proliferation (11). Several genes that are repressed by REST in myocytes have been identified, including the genes encoding the brain and atrial natriuretic peptides (Nppb and Nppa, encoding BNP and ANP, respectively), ␣-skeletal actin (Acta1), potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channels 2 and 4 (Hcn2 and Hcn4), and voltage-gated calcium channel subunit alpha Cav3.2 (Cacna1h) (26, 43). Levels of BNP and ANP are particularly important, since increased levels of these peptides in circulation are clinical indicators of the severity of hypertrophy (8,29,38,61)....