Biology subjects

Grichine, A.

Publications and source records attributed to Grichine, A..

5 recordsLinked to original sources

bioRxiv2026

Hck signaling drives long-distance ECM degradation through endo-exocytosis coupling in macrophages.

The diversity of strategies implicated in extracellular matrix (ECM) degradation supporting cell invasion has been poorly achieved. Unlike invasive breast cancer cells, which predominantly degrade the ECM locally via an invadosome-associated degradation, dynamic quantification of live imaging of degradation of physiological ECM such as fibrinogen showed that macrophages employ different modes of ECM degradation since digesting ECM both locally and at long distance. Long distance degradation occurring in macrophage is dependent on both matrix metalloproteases (MMPs) and cathepsins release. Optogenetic manipulation showed that HCK signaling specifically regulates positively this new mode of fibrinogen degradation by increasing cathepsins release and activating localized fusion of acidic CD63-endolysosome vesicles at the vicinity of clathrin hotspots at the rear of macrophages, appearing as a new exo-endocytosis coupling. Computational biology and in silico simulations support the importance of the fine spatiotemporal coordination between MMPs and cathepsin activities, and regulation of cathepsin activity by local acid release. Different mode of ECM degradation can thus coexist and this highlight the importance of understanding the cathepsins-MMPs synergy in shaping invasive behavior across different physio-pathological invasion processes.

cell biology↗

bioRxiv2026

Winding-Up of Fibrin Fibers as a Novel Mechanism of Platelet-Mediated Fiber Compaction

This study reveals a previously unrecognized mechanism by which platelets retract and compact fibrin fibers. Using a newly developed 2D fiber-retraction assay, we observed an initial "gearwheel" pattern of actin-myosin organization in spread platelets with associated, extracellular fibrin patches that appear to form an initiation complex for fibrin fiber attachment and rearrangement. The final outcome of this process results in two morphologically different platelet populations. Spread platelets with coiled fibers around and above their pseudo-nucleus. Other platelets are only partially spread on the glass surface and are surrounded by tightly packed fibrin fibers around bulbous protrusions ("bulbs"), mirroring the architecture of platelets and adjacent fibers within a retracted clot. Thus, the observed compaction process might also take place during clot retraction in order to reduce clot volume, stiffen the clot and enhance wound repair. Apart from pulling on fibers like on a rope, platelets actively wrap fibrin fibers into compact structures, similar to balls of wool. Besides DNA packaging, this represents a new example of a natural fiber compaction mechanism. Using a combination of 3D clot-retraction and 2D fiber-retraction assays, expansion and electron microscopy, live imaging and mathematical modeling, we show that platelets use an actomyosin-driven motion to gather and loop fibrin fibers around the base of bulbous protrusions. These bulbs form when a platelet becomes trapped between fibrin fibers during 3D clot retraction or 2D fiber-retraction assays. These findings complement and extend earlier models of platelet-mediated fibrin fiber retractions, offering new insight into how platelets mechanically organize fibrin fibers.

cell biology↗

bioRxiv2025

Optogenetic SH3 nanoclustering of SRC and HCK uncovers the functional specificity of these redundant kinases in macrophages.

Understanding redundancy among Src Family Kinases (SFKs) challenges how cells achieve signaling specificity using closely related enzymes, and paves the way to revisit a basic property of any cell signaling network. Optogenetic control of the adaptor properties of the most redundant SFK members, SRC and HCK, was used to examine their potential specificity in macrophages. Uncoupling their kinase and adaptor functions uncovers an unique mechanism driven by oligomerized- and SH3-dependent specific binding that enables inducing distinct signaling outputs for each kinase. OptoSRC and optoHCK probes revealed that SRC and HCK can trigger specific cellular responses, despite only supposed overlapping functions. The specificity of optoHCK even unveils a novel role in activating polarized clathrin hotspots essential for directional migration. Redundancy could be rebuilt within optoHCK through stepwise optogenetic reconstruction of adaptor modules revealing the essential role of both membrane anchoring and SH2-domain. This deconstructive approach of SFK activation elucidated the molecular basis of their shared and unique signaling activities and supports a model of cooperative functional entanglement between SFK members, rather than simple redundancy.

cell biology↗

bioRxiv2025

The metabolic kinase LKB1 shapes the enteric nervous system bymitigating the oxidative stress and p53 activity

The enteric nervous system (ENS) comprises ganglia of neurons and glial cells derived from migratory multipotent neural crest cells. While the molecular mechanisms of ENS development are well-studied, the involvement of metabolic processes has received less attention. We previously showed that the tumor suppressor kinase LKB1 is essential for the trophic maintenance of postnatal ENS. Here we examined LKB1s role in ENS formation using a genetically engineered mouse model that conditionally inactivates Lkb1 in neural crest progenitors during gut invasion. We conducted a comprehensive phenotyping of the ENS through histology and 3D imaging of cleared tissue, combining lightsheet microscopy with adaptive optics confocal microscopy. We found that Lkb1 loss impairs early neuronal differentiation, followed by glial degeneration, leading to hypoganglionosis and compromised digestive tissue integrity. Metabolite profiling of digestive tracts revealed an increase of oxidative stress upon Lkb1 ablation. In vitro, Lkb1 knockdown induced oxidative stress in neural crest progenitors and their glial derivatives, causing DNA damage and p53 activation. Ablation of p53 rescued glial specification under these conditions. In vivo, hyperphosphorylation of p53 was also observed; however, deletion of p53 alleles in Lkb1 mutants did not restore enteric neurons number. Instead, it improved axonal fiber organization and partially rescued digestive tissue integrity. These findings establish LKB1 as a key metabolic regulator on both the development and maintenance of the ENS, suggesting that aberrant LKB1 signaling may contribute to human enteric glioneuropathies. HighlightsO_LILKB1 loss in enteric progenitors results in extensive hypoganglionosis and disrupts gut tissue homeostasis. C_LIO_LIDuring embryogenesis, LKB1 shapes enteric ganglia by sequentially regulating neuronal differentiation and preserving glial cells, partly by limiting oxidative stress and p53 activity. C_LIO_LIThese findings establish LKB1 as a critical regulator of neural crest cell formation, highlighting its multifaceted roles and potential pathological implications in digestive neuropathies. C_LI

developmental biology↗

bioRxiv2019

Molecular flux control encodes distinct cytoskeletal responses by specifying SRC signaling pathway usage.

Multi-domain signaling proteins sample numerous stimuli to coordinate distinct cellular responses. Understanding the mechanisms of their pleiotropic signaling activity requires to directly manipulate their activity of decision leading to distinct cellular responses. We developed an optogenetic probe, optoSRC, to control spatio-temporally the SRC kinase, a representative example of versatile signaling node, and challenge its ability to generate different cellular responses. Genesis of different local molecular fluxes of the same optoSRC to adhesion sites, was sufficient to trigger distinct and specific acto-adhesive responses. Collectively, this study reveals how hijacking the pleiotropy of SRC signaling by modulating in space and time subcellular molecular fluxes of active SRC kinases.

cell biology↗