Papers by Elisabeth Ehler
bioRxiv (Cold Spring Harbor Laboratory), Jul 19, 2023
Mechanical properties are cues for many biological processes in health or disease. Likewise, in t... more Mechanical properties are cues for many biological processes in health or disease. Likewise, in the heart it is becoming clearer that mechanical signals are critically involved in the disease progression. Cardiomyocytes sense the mechanical properties of their environment at costameres through integrins and associated proteins, including the mechanosensitive protein talin as an integral component. Our previous work indicated different modes of talin tension, depending on the extracellular matrix stiffness. Here, we wanted to study how this leads to downstream mechanotransduction changes, further influencing the cardiomyocyte phenotype. Combining immunoprecipitations and Fluorescence Recovery after Photobleaching (FRAP) experiments, we identify that the talin interacting proteins DLC1, RIAM and paxillin each preferentially bind to talin at specific extracellular matrix stiffness and this interaction is preserved even in absence of tension. This demonstrates a mechanical memory, which we confirm further in vivo in mouse hearts. The mechanical memory is regulated through adhesion related kinase pathways. Optogenetic experiments using the LOVTRAP systems confirm direct competition between the individual proteins, which again is altered through phosphorylation. DLC1 regulates RhoA activity in a stiffness dependent way and both loss and overexpression of DLC1 results in myofibrillar disarray. Together the study demonstrates a mechanism of imprinting mechanical information into the talininteractome to finetune RhoA activity, with impacts on cardiac health and disease.
compared to WT and MD FLT4, which exhibit mainly plasma membrane staining (Figure ). TOF FLT4 PTV... more compared to WT and MD FLT4, which exhibit mainly plasma membrane staining (Figure ). TOF FLT4 PTVs are expressed, but at a lower level than WT, however, this can be augmented by treatments simulating low oxygen levels. Transcriptomic analyses revealed a subset of DEGs that are TOF FLT4-specific compared to both WT and MD expressing cells (TFSGs, Table ). Gene ontology analysis showed that TFSGs were enriched for proteostatic, metabolic and developmental signalling processes. TFSGs were also compared with stably heart expressed developmental genes (SHDGs) and showed significant overlap when examined by permutation testing (Figure ), directly linking in vitro and in vivo transcriptomic data. Inhibitors of all three proteostatic signalling pathways rescued TFSG expression changes, to differing degrees, confirming the mechanism of pathogenesis for FLT4 variants in TOF. Conclusions We demonstrate a gain-of-function mechanism, with varying degrees of penetrance, that is responsible for the TOF phenotype. This contrasts with the already established dominant negative mechanism, that leads to Milroy lymphoedema with other FLT4 variants. Our results succinctly delineate the mechanisms of FLT4 pleiotropy in two unrelated cardiovascular conditions and suggest that targeting proteostatic signalling could identify potential pathways to therapeutic interventions in FLT4-associated TOF.
Journal of Experimental Medicine, Sep 21, 2015
Biophysical Reviews, Sep 9, 2021
Muscle specific signaling has been shown to originate from myofilaments and their associated cell... more Muscle specific signaling has been shown to originate from myofilaments and their associated cellular structures, including the sarcomeres, costameres or the cardiac intercalated disc. Two signaling hubs that play important biomechanical roles for cardiac and/or skeletal muscle physiology are the N2B and N2A regions in the giant protein titin. Prominent proteins associated with these regions in titin are chaperones Hsp90 and αB-crystallin, members of the four-and-a-half LIM (FHL) and muscle ankyrin repeat protein (Ankrd) families, as well as thin filament-associated proteins, such as myopalladin. This review highlights biological roles and properties of the titin N2B and N2A regions in health and disease. Special emphasis is placed on functions of Ankrd and FHL proteins as mechanosensors that modulate muscle-specific signaling and muscle growth. This region of the sarcomere also emerged as a hotspot for the modulation of passive muscle mechanics through altered titin phosphorylation and splicing, as well as tethering mechanisms that link titin to the thin filament system.
Biochemical Journal, Nov 1, 2002
During an ischaemic insult, oedema formation occurs as a consequence of increased vascular permea... more During an ischaemic insult, oedema formation occurs as a consequence of increased vascular permeability. To study mechanisms leading to vascular barrier failure, endothelial cells were exposed to ischaemia (1 % O # in serum-and glucose-free medium) for 5 h. In in itro conditions, ischaemia increased paracellular permeability, disassembled actin stress fibres, displaced focal adhesion kinase (FAK) from focal adhesions and enhanced cytoskeletal association of occludin. Reoxygenation restored paracellular barrier function, actin organization and FAK distribution. The mitogen-activated protein kinase (MAPK)\ extracellular signal-regulated protein kinase (ERK) was rapidly activated after 30 min, strongly inhibited after 5 h of continuous ischaemia and reactivated 3 times more than control during
Biophysical Journal, 2018
Journal of Cell Science, 1999
Vertebrate tropomyosins (TMs) are expressed from four genes, and at least 18 distinct isoforms ar... more Vertebrate tropomyosins (TMs) are expressed from four genes, and at least 18 distinct isoforms are generated via a complex pattern of alternative RNA splicing and alternative promoters. The functional significance of this isoform diversity is largely unknown and it remains to be determined whether specific isoforms are required for assembly and integration into distinct actin-containing structures. The ability of nonmuscle (TM-1, -2, -3, -4, -5(NM1), -5a or -5b) and striated muscle (skeletal muscle α-TM) isoforms to incorporate into actin filaments of neonatal rat cardiomyocytes (NRCs) was studied using expression plasmids containing TM-fusions with GFP (green fluorescent protein) as well as with VSV-or HA-epitope tags. All isoforms, except of fibroblast TM-4, were able to incorporate into the I-band of NRCs. When TM-4 was co-transfected with other low molecular weight (LMW) isoforms of TM (TM-5, TM-5a and TM-5b), it was able to incorporate into sarcomeres of NRCs. This result was n...
Journal of Cell Science, 1999
Regulation of epithelial and endothelial permeability is essential for proper function of compart... 
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Papers by Elisabeth Ehler