Biology subjects

Lambert, I.

Publications and source records attributed to Lambert, I..

3 recordsLinked to original sources

bioRxiv2025

Knockdown of endothelial Serpine1 improves stroke recovery by attenuating peri-infarct blood flow and blood brain barrier disruption

Focal stroke leads to complex changes in the cerebral microcirculation in surviving brain tissues that strongly influence recovery. Plasminogen activator inhibitor-1 (PAI-1; encoded by Serpine1) is highly upregulated in endothelial cells after stroke. Since the primary function of PAI-1 is to inhibit fibrin clot breakdown, we hypothesized that blocking this pathway would be beneficial for recovery since it is expected to increase capillary blood flow after stroke. Using longitudinal in vivo imaging in mice subjected to ischemic stroke, we unexpectedly found that knockdown of Serpine1 in brain endothelial cells leads to a long-lasting reduction in peri-infarct capillary width, red blood cell velocity and flux. Conversely, stimulating this pathway in naive mice increased capillary width and blood flow. Lowered peri-infarct blood flow in Serpine1 knockdown mice attenuated deleterious blood brain barrier disruption and pro-inflammatory gene expression. Serpine1 knockdown improved the progressive recovery of sensory evoked cortical responses, as well as cognitive and sensorimotor function. These findings challenge the assumption that increased blood flow after stroke is better for recovery and reveal that carefully tuning flow, rather than maximizing it, may be optimal. Further our data highlight the therapeutic potential of targeting endothelial Serpine1/PAI-1 signalling in promoting stroke recovery.

neuroscience↗

bioRxiv2025

New Swiss-knife activities of GroEL/Hsp60 proteins

GroEL/Hsp60 chaperonins are key proteins that control cell metabolism, stress adaptation and survival. They usually form a tetradecameric structure that assists, coupled to ATP hydrolysis, 10% of all cellular protein folding. Using recombinant E. coli, human mitochondrial and M. tuberculosis chaperonins, we found that these proteins have thioesterase, esterase and even, for some of them, auto-acyltransferase activities. The smaller oligomers of Hsp60 and M. tuberculosis GroEL1 were more prone to use the long acyl carbon chain substrate palmitoyl-CoA compared to tetradecameric E. coli GroEL and Hsp60. Enzymatic competition and replacement of M. tuberculosis GroEL1 residues allow identifying Asp86 and Thr89 in the ATP-binding pocket and an additional Ser393 influencing the thioesterase activity. Additionally, M. tuberculosis GroEL1 might enhance palmitoylation of the PpsE protein, which plays a role in the phthiocerol dimycocerosate (PDIM) biosynthesis. This could explain at least partly the involvement of GroEL1 in PDIM biosynthesis and antibiotic resistance.

biochemistry↗

bioRxiv2021

Autoregulation dependent and independent mechanisms are responsible for the systemic control of nodule formation by the plant N demand

In legumes interacting with rhizobia the formation of symbiotic organs responsible for the acquisition of atmospheric nitrogen is depending of the plant nitrogen (N) demand. We discriminated between local and systemic impact of nitrogen on nodule formation using Medicago truncatula plants cultivated in split-root systems. We obtained evidence of the control of nodule formation by whole plant systemic N-satisfaction signaling but obtained little evidence of a local control by mineral nitrogen. We characterized the impact of systemic N signaling on the root transcriptome reprogramming associated to nodule formation. We identified, large genes clusters displaying common expression profiles in response to systemic N signaling enriched in particular fonctions required during these biological processes. We found evidence of a strong effect of SUNN in the control by systemic N signaling of many genes involved in the early interaction with rhizobium as well as organogenesis supporting a role of autoregulation pathway in systemic N signaling. However, we also found evidence that major SUNN independent systemic N signaling controls were maintained in the mutant. This study shed light on the unexpected high complexity of the control of nodule formation by systemic N signaling, that probably involves multiple pathways.

plant biology↗