Biology subjects

Lerche, M.

Publications and source records attributed to Lerche, M..

5 recordsLinked to original sources

bioRxiv2025

The Rise and Fall of SARM1 Base-Exchange Inhibitors

The sterile alpha and TIR motif containing 1 (SARM1) enzyme is a key driver of axonal degeneration in response to injury, making it an attractive target for treating chemotherapy-induced peripheral neuropathy (CIPN) and other nervous system diseases. In this study, we identified and optimised a new class of base-exchange inhibitors (BEXi) targeting SARM1 and explored their molecular interactions and conformational effects using cryo-EM, HDX-MS and SAXS. Although BEXi produced robust inhibition across all biochemical and cellular assay formats, application at sub-inhibitory concentrations consistently led to paradoxical SARM1 activation, and in neuronal assays, accelerated neurite degeneration. Further analysis showed that BEXi only delayed, rather than prevented, neurite degeneration when applied to primary neuronal cells, even at exceedingly high inhibitor concentrations. These results prompted us to discontinue BEXi development in favour of alternative strategies, underscoring the complexity of SARM1 as a therapeutic target and the need for comprehensive, mechanistically informed screening cascades.

neuroscience↗

bioRxiv2022

Regulation of cell dynamics by rapid transport of integrins through the biosynthetic pathway

Cells sense and respond to the extracellular matrix (ECM) milieu through integrin proteins. Integrin availability on the plasma membrane, regulated by endosomal receptor uptake and recycling, has been extensively studied and regulates cell dynamics in various normal and pathological contexts1-5. In contrast, the role of integrin transport through the biosynthetic pathway has been considered primarily as a mechanism to replenish the receptor pool and too slow to influence cell dynamics6. Here, we adopted the RUSH (Retention Using Selective Hooks) assay to synchronize integrin anterograde transport from the endoplasmic reticulum (ER), allowing spatial and temporal analysis of newly synthesized receptor traffic. We observe that the delivery of new integrins to the plasma membrane is polarized in response to specific ECM ligands, facilitates integrin recruitment specifically to the membrane-proximal tip of focal adhesions (FA) and contributes to cell protrusion and FA growth. We explain the augmented adhesion growth using a computational molecular clutch model7, where increased integrin availability drives recruitment of additional integrins. Notably, a subset of newly synthesized integrins undergo rapid traffic from the ER to the cell surface to facilitate localized cell spreading, seemingly bypassing the Golgi. This unconventional secretion is dependent on cell adhesion and mediated by Golgi reassembling stacking proteins (GRASPs) association with the PDZ-binding motif in the integrin 5 cytoplasmic tail. This spatially targeted delivery of integrins through the biosynthetic pathway may propel cell dynamics by rapidly altering adhesion receptor availability, providing cells with an additional degree of plasticity to respond to their environment.

cell biology↗

bioRxiv2020

ZeroCostDL4Mic: an open platform to simplify access and use of Deep-Learning in Microscopy

The resources and expertise needed to use Deep Learning (DL) in bioimaging remain significant barriers for most laboratories. We present https://github.com/HenriquesLab/ZeroCostDL4Mic/wiki, a platform simplifying access to DL by exploiting the free, cloud-based computational resources of Google Colab. https://github.com/HenriquesLab/ZeroCostDL4Mic/wiki allows researchers to train, evaluate, and apply key DL networks to perform tasks including segmentation, detection, denoising, restoration, resolution enhancement and image-to-image translation. We demonstrate the application of the platform to study multiple biological processes.

bioinformatics↗

bioRxiv2019

Integrin binding dynamics modulate ligand-specific mechanosensing in mammary gland fibroblasts

The link between the modulation of integrin activity and cellular mechanosensing of tissue rigidity, especially on different extracellular matrix ligands, remains poorly understood. Here, we find that primary mouse mammary gland stromal fibroblasts (MSFs) are able to spread efficiently on soft collagen-coated substrates, resembling the soft mammary gland tissue. In addition, MSFs generate high forces and display nuclear YAP at a low matrix stiffness, supported by mature focal adhesions, prominent actin stress fibers, and myosin phosphorylation. We describe that loss of the cytosolic integrin inhibitor, SHARPIN, impedes MSF spreading specifically on soft type I collagen but not on fibronectin. Through quantitative experiments and computational modelling, we find that SHARPIN-deficient MSFs display faster force-induced unbinding of adhesions from collagen-coated beads. Faster unbinding, in turn, impairs force transmission in these cells, particularly, at the stiffness optimum observed for wild-type cells, and increases actin retrograde flow. Mechanistically, we link the impaired mechanotransduction of SHARPIN-deficient cells on collagen to reduced levels of the collagen-binding integrin 11{beta}1. Our results unveil a collagen-specific mechanosensing mechanism and suggest a key function for integrin activity regulation and integrin 11{beta}1 in MSF mechanotransduction.

cell biology↗

bioRxiv2018

Metal-independent ribonucleotide reduction powered by a DOPA radical in Mycoplasma pathogens

Ribonucleotide reductase (RNR) catalyzes the only known de-novo pathway for production of all four deoxyribonucleotides required for DNA synthesis. In aerobic RNRs, a di-nuclear metal site is viewed as an absolute requirement for generating and stabilizing an essential catalytic radical. Here we describe a new group of RNRs found in Mollicutes, including Mycoplasma pathogens, that possesses a metal-independent stable radical residing on a modified tyrosyl residue. Structural, biochemical and spectroscopic characterization reveal a stable DOPA radical species that directly supports ribonucleotide reduction in vitro and in vivo.\n\nThe cofactor synthesis and radical generation processes are fundamentally different from established RNRs and require the flavoprotein NrdI. Several of the pathogens encoding this RNR variant are involved in diseases of the urinary tract and genitalia. Conceivably, this remarkable RNR variant provides an advantage under metal starvation induced by the immune system. We propose that the new RNR subclass is denoted class Ie.

biochemistry↗