Biology subjects

Pauwels, E.

Publications and source records attributed to Pauwels, E..

3 recordsLinked to original sources

bioRxiv2022

Structural insights into TRAP association with ribosome-Sec61 complex, and translocon inhibition by a CADA derivative

During co-translational translocation, the signal peptide of a nascent chain binds Sec61 translocon to initiate protein transport through the ER membrane. Our cryo-EM structure of ribosome-Sec61 shows binding of an ordered heterotetrameric TRranslocon-Associated Protein (TRAP) complex, in which TRAP-{gamma} is anchored at two adjacent positions of 28S rRNA and interacts with ribosomal protein L38 and Sec61/{gamma}. Four transmembrane helices (TMHs) of TRAP-{gamma} cluster with one C-terminal helix of each , {beta}, and {delta} subunits. The seven TMH bundle helps position a crescent-shaped trimeric TRAP-/{beta}/{delta} core in the ER lumen, facing the Sec61 channel. Further, our in vitro assay establishes the CADA derivative CK147 as a translocon inhibitor. A structure of ribosome-Sec61-CK147 reveals CK147 binding the channel and interacting with the plug helix from the lumenal side. The CK147-resistance mutations surround the inhibitor. These structures help in understanding the TRAP functions and provide a new Sec61 site for designing translocon inhibitors. Short SummaryCryo-EM structures reveal TRAP binding to ribosome-Sec61 complex, and CK147 inhibiting Sec61 by arresting the plug helix inside the channel.

cell biology↗

bioRxiv2022

Effect of biomaterial stiffness on cardiac mechanics in a biventricular infarcted rat heart model with microstructural representation of in situ intramyocardial injectate

Intramyocardial delivery of biomaterials is a promising concept for treating myocardial infarction. The delivered biomaterial provides mechanical support and attenuates wall thinning and elevated wall stress in the infarct region. This study aimed at developing a biventricular finite element model of an infarcted rat heart with a microstructural representation of an in situ biomaterial injectate, and a parametric investigation of the effect of the injectate stiffness on the cardiac mechanics. A three-dimensional subject-specific biventricular finite element model of a rat heart with left ventricular infarct and microstructurally dispersed biomaterial delivered one week after infarct induction was developed from ex vivo microcomputed tomography data. The volumetric mesh density varied between 303 mm-3 in the myocardium and 3,852 mm-3 in the injectate region due to the microstructural intramyocardial dispersion. Parametric simulations were conducted with the injectates elastic modulus varying from 4.1 to 405,900 kPa, and myocardial and injectate strains were recorded. With increasing injectate stiffness, the end-diastolic median myocardial fibre and cross-fibre strain decreased in magnitude from 3.6% to 1.1% and from -6.0% to -2.9%, respectively. At end-systole, the myocardial fibre and cross-fibre strain decreased in magnitude from -20.4% to -11.8% and from 6.5% to 4.6%, respectively. In the injectate, the maximum and minimum principal strains decreased in magnitude from 5.4% to 0.001% and from -5.4% to -0.001%, respectively, at end-diastole and from 38.5% to 0.06% and from -39.0% to -0.06%, respectively, at end-systole. With the microstructural injectate geometry, the developed subject-specific cardiac finite element model offers potential for extension to cellular injectates and in silico studies of mechanotransduction and therapeutic signalling in the infarcted heart with an infarct animal model extensively used in preclinical research.

biophysics↗

bioRxiv2021

Simultaneous inhibition of human CD4 and 4-1BB biogenesis suppresses cytotoxic T lymphocyte proliferation

The small molecule cyclotriazadisulfonamide (CADA) down-modulates the human CD4 receptor, an important factor in T cell activation. Here, we addressed the immunosuppressive potential of CADA using in vitro activation models. CADA inhibited lymphocyte proliferation in a mixed lymphocyte reaction, and when human PBMCs were stimulated with CD3/CD28 beads or phytohemagglutinin. The immunosuppressive effect of CADA involved both CD4+ and CD8+ T cells but was, surprisingly, most prominent in the CD8+ T cell subpopulation where it inhibited cell-mediated lympholysis. We discovered a direct down-modulatory effect of CADA on 4-1BB (CD137) expression, a survival factor for activated CD8+ T cells. More specifically, CADA blocked 4-1BB protein biosynthesis by inhibition of its co-translational translocation across the ER membrane in a signal peptide-dependent way. This study demonstrates that CADA, as potent down-modulator of human CD4 and 4-1BB, has promising in vitro immunomodulatory characteristics for future in vivo exploration as immunosuppressive drug.

immunology↗