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Roldan, E.

Publications and source records attributed to Roldan, E..

3 recordsLinked to original sources

Bringing calorimetry (back) to life

Micro-calorimetry offers significant potential as a quantitative method for studying the structure and function of biological systems, for instance, by probing the excess heat released by cellular or sub-cellular structures, isothermal or not, when external parameters change. We present the conceptual framework of nonequilibrium calorimetry, and as illustrations, we compute the heat capacity of biophysical models with few degrees of freedom related to ciliar motion (rowing model) and molecular motor motion (flashing ratchets). Our quantitative predictions reveal intriguing dependencies of the (nonequilibrium) heat capacity as a function of relevant biophysical parameters, which can even take negative values as a result of biological activity.

biophysics↗

Bisphosphonates Trigger Anti-Ageing Effects Across Multiple Cell Types and Protect Against Senescence

Bisphosphonates (BPs) have been the major class of medicines used to treat disorders of excessive bone loss for over five decades. Recently it has been recognized that BPs may also have additional significant beneficial extra-skeletal effects. These include a reduction of all-cause mortality and of conditions commonly linked to ageing, such as cancer and cardiovascular disease. Here we show that bisphosphonates co-localize with lysosomal and endosomal organelles in non-skeletal cells and stimulate cell growth at low doses. In vivo spatial transcriptomic analysis revealed differentially expressed senescence markers in multiple organs of aged BP-treated mice, and a shift in cellular composition toward those of young counterparts. Similarly, a 5000-plex plasma proteome analysis from osteopenic patients before and after BP-treatment showed significant alterations in [~]400 proteins including GTPase regulators and markers of senescence, autophagy, apoptosis, and inflammatory responses. Furthermore, treatment with BPs protected against the onset of senescence in vitro. Proteome-wide target deconvolution using 2D thermal profiling revealed novel BP-binding targets (PHB2, ASAH1), and combined with RNA- and ATAC-seq of BP-treated cells and patient data, suggests downstream regulation of the MEF2A transcription factor within the heart. Collectively, these results indicate how BPs may beneficially modify the human plasma proteome, and directly impact multiple non-skeletal cell types through previously unidentified proteins, thereby influencing a range of pathways related to senescence and ageing.

cell biology↗

Protamine sequence determines species-specific nuclear shape and histone retention

Nuclear shape observed after the forced expression of mouse or human Protamine 1 (PRM1) in fibroblasts led us to propose the hypothesis that PRM1 sequence plays an important role in imposing the overall shape of the protaminized nucleus. Comparison of mouse and human PRM1 sequence pointed to cysteines 15 and 29 as potential critical residues in the mouse PRM1 sequence inducing the characteristic mouse "hooked" nuclear sperm shape. To explore this idea, mice with mutations in PRM1 Cys15 and Cys29 were generated. These mice remained fertile with no significant changes in sperm count or protamine expression levels. However, modifications in sperm head shape were observed. Transmission electron microscopy revealed disrupted chromatin condensation in mutant sperm, with several morphological changes and a remarkable increase in histone retention. Overall, the findings suggest that species-specific PRM1 cysteine residue positions are crucial for nuclear shape determination and histone retention in spermatozoa.

developmental biology↗