Shengpeng Wang

The liver exhibits a marked regenerative capacity organized through distinct zones, yet how tissue mechanics coordinate zonated proliferation remains elusive. We reveal that mechanical cues critically contribute to mouse liver regeneration in a highly region-specific manner through sensing by a subpopulation of mid-lobular hepatocytes, which are characterized by dipeptidyl peptidase-4 (DPP4) expression and represent the key proliferative pool of hepatocytes. PIEZO1 is a primary mechanosensor enriched in zone 2 DPP4 ⁺ hepatocytes that integrates biomechanical cues to drive liver regrowth by insulin-like growth factor binding protein 2 (IGFBP2). Genetic disruption of PIEZO1 restrains hepatocyte proliferation and compromises liver regeneration, whereas zonated PIEZO1 gain of function enhances proliferation and accelerates recovery. These findings reveal that DPP4 ⁺ mechanosensitive hepatocytes orchestrate liver regrowth through PIEZO1-mediated mechanosensing, establishing a link between tissue mechanics and liver regeneration.

Aims: Pulmonary artery smooth muscle cells (PASMCs) sense and respond to constant mechanical strain, which is vital for lung homeostasis and disease. Mechanical stimuli and altered glycolytic metabolism are intrinsically intertwined in proliferative PASMCs undergoing a phenotypic switching, however, it remains unclear how biophysical forces and glycolysis are coupled in PASMCs. We report that PIEZO1 plays a critical role in PASMC metabolism and distinguishable mechanical cues differently rewire PIEZO1-mediated signalling into pro- and anti-glycolytic metabolism. Methods and results: Under hypoxia, activation of PIEZO1 promotes glycolysis in PASMCs through HIF1α and PFKFB3, resulting in profound lactate production and cell proliferation. In severe pulmonary injury induced by bleomycin, PIEZO1 is hyper-activated, which led to PPARγ activation, thereby antagonizing TGFβ signalling and restraining glycolysis and proliferation via FBP1. Loss of smooth muscle Piezo1 attenuates pneumonectomy and hypoxia induced PASMC growth and vascular remodelling, while aggravates pulmonary fibrosis in mice. Conclusion: Our study reveals that PIEZO1-mediated mechano-metabolic coupling contributes to PASMCs plasticity. This discovery identified an intrinsic mechanism that integrates mechanical stretch with cellular glycolysis during pulmonary vascular remodelling.

The function of islet macrophages is poorly understood. They promote glucose-stimulated insulin secretion (GSIS) in lean mice, however, the underlying mechanism has remained unclear. We show that activation of the free fatty acid receptor FFAR4 on islet macrophages leads to interleukin-6 (IL-6) release and that IL-6 promotes β-cell function. This mechanism is required for GSIS in lean male mice, but does not function anymore in islets from people with obesity and obese type 2 diabetic male mice. In islets from obese mice, FFAR4 downstream signaling in macrophages is strongly reduced, resulting in impaired FFAR4-mediated IL-6 release. However, IL-6 treatment can still improve GSIS in islets from people with obesity and obese type 2 diabetic mice. These data show that a defect in FFAR4-mediated macrophage activation contributes to reduced GSIS in type 2 diabetes and suggest that reactivating islet macrophage FFAR4 and promoting or mimicking IL-6 release from islet macrophages improves GSIS in type 2 diabetes.

Insulin resistance is a hallmark of obesity-associated type 2 diabetes. Insulin’s actions go beyond metabolic cells and also involve blood vessels, where insulin increases capillary blood flow and delivery of insulin and nutrients. We show that adrenomedullin, whose plasma levels are increased in obese humans and mice, inhibited insulin signaling in human endothelial cells through protein-tyrosine phosphatase 1B–mediated dephosphorylation of the insulin receptor. In obese mice lacking the endothelial adrenomedullin receptor, insulin-induced endothelial nitric oxide–synthase activation and skeletal muscle perfusion were increased. Treating mice with adrenomedullin mimicked the effect of obesity and induced endothelial and systemic insulin resistance. Endothelial loss or blockade of the adrenomedullin receptor improved obesity-induced insulin resistance. These findings identify a mechanism underlying obesity-induced systemic insulin resistance and suggest approaches to treat obesity-associated type 2 diabetes.

Atherosclerotic lesions develop preferentially in arterial regions exposed to disturbed blood flow, where endothelial cells acquire an inflammatory phenotype. How disturbed flow induces endothelial cell inflammation is incompletely understood. Here we show that histone H3.3 phosphorylation at serine 31 (H3.3S31) regulates disturbed-flow-induced endothelial inflammation by allowing rapid induction of FOS and FOSB, required for inflammatory gene expression. We identified protein kinase N1 (PKN1) as the kinase responsible for disturbed-flow-induced H3.3S31 phosphorylation. Disturbed flow activates PKN1 in an integrin α5β1-dependent manner and induces its translocation into the nucleus, and PKN1 is also involved in the phosphorylation of the AP-1 transcription factor JUN. Mice with endothelium-specific PKN1 loss or endothelial expression of S31 phosphorylation-deficient H.3.3 mutants show reduced endothelial inflammation and disturbed-flow-induced vascular remodeling in vitro and in vivo. Together, we identified a pathway whereby disturbed flow through PKN1-mediated histone phosphorylation and FOS/FOSB induction promotes inflammatory gene expression and vascular inflammation.

Inflammation is a protective response to pathogens and injury. To be effective it needs to be resolved by endogenous mechanisms in order to avoid prolonged and excessive inflammation, which can become chronic. Specialized pro-resolving mediators (SPMs) are a group of lipids derived from omega-3 fatty acids, which can induce the resolution of inflammation. How SPMs exert their anti-inflammatory and pro-resolving effects is, however, not clear. Here, we show that SPMs such as protectins, maresins, and D-series resolvins function as biased positive allosteric modulators (PAM) of the prostaglandin E ₂ (PGE ₂ ) receptor EP4 through an intracellular binding site. They increase PGE ₂ -induced G _s -mediated formation of cAMP and thereby promote anti-inflammatory signaling of EP4. In addition, SPMs endow the endogenous EP4 receptor on macrophages with the ability to couple to G _i -type G-proteins, which converts the EP4 receptor on macrophages from an anti-phagocytotic receptor to one increasing phagocytosis, a central mechanism of the pro-resolving activity of synthetic SPMs. In the absence of the EP4 receptor, SPMs lose their anti-inflammatory and pro-resolving activity in vitro and in vivo. Our findings reveal an unusual mechanism of allosteric receptor modulation by lipids and provide a mechanism by which synthetic SPMs exert pro-resolving and anti-inflammatory effects, which may facilitate approaches to treat inflammation.

Objective: Transcranial focused ultrasound (tFUS) neuromodulation offers a noninvasive, safe, deep brain stimulation with high precision, presenting potential in understanding neural circuits and treating brain disorders. This in vivo study investigated the mechanism of tFUS in activating the opening of the mechanosensitive ion channels Piezo1 and Piezo2 in the mouse motor cortex to induce motor responses. Methods: Piezo1 and Piezo2 were knocked down separately in the mouse motor cortex, followed by EMG and motor cortex immunofluorescence comparisons before and after knockdown under tFUS stimulation. Results: The results demonstrated that the stimulation-induced motor response success rates in Piezo knockdown mice were lower compared to the control group (Piezo1 knockdown: 57.63% ± 14.62%, Piezo2 knockdown: 73.71% ± 13.10%, Control mice: 85.69% ± 10.23%). Both Piezo1 and Piezo2 knockdowns showed prolonged motor response times (Piezo1 knockdown: 0.62 ± 0.19 s, Piezo2 knockdown: 0.60 ± 0.13 s, Control mice: 0.44 ± 0.12 s) compared to controls. Additionally, Piezo knockdown animals subjected to tFUS showed reduced immunofluorescent c-Fos expression in the target area when measured in terms of cells per unit area compared to the control group. Conclusion: This in vivo study confirms the pivotal role of Piezo channels in tFUS-induced neuromodulation, highlighting their influence on motor response efficacy and timing. Significance: This study provides insights into the mechanistic underpinnings of noninvasive brain stimulation techniques and opens avenues for developing targeted therapies for neural disorders.