Project description:Understanding the intricate cellular interactions involved in bone restoration is crucial for developing effective strategies to promote bone healing and mitigate conditions such as osteoporosis and fractures. Here, we provide compelling evidence supporting the anabolic effects of a pharmacological Pyk2 inhibitor (Pyk2-Inh) in promoting bone restoration. Using an ovariectomized mouse model, we administered Pyk2-Inh orally, resulting in increased bone mass characterized by reduced bone resorption, increased bone formation and decreased bone marrow fat. In vitro, Pyk2 inhibition significantly impedes osteoclast differentiation and bone resorption. In a co-culture system comprising osteoblasts and osteoclasts, Pyk2-Inh effectively suppressed osteoclast differentiation, accompanied by a substantial increase in the transcriptional expression of Tnfrsf11b and Csf1 in osteoblasts. Additionally, Pyk2 signaling inhibition markedly enhances alkaline phosphatase (ALP) activity, a hallmark of osteoblast differentiation, through an increase in canonical Wnt/β-catenin signaling. Notably, analysis of human mesenchymal stem cells through RNA-seq revealed a novel candidate, SCARA5, identified through Pyk2-Inh treatment. We demonstrate that Scara5 plays a crucial role in suppressing the differentiation from stromal cell into adipocytes, and accelerates lineage commitment to osteoblasts, establishing Scara5 as a negative regulator of bone formation. These results suggest Pyk2 as a potential therapeutic target for both adipogenesis and osteogenesis in bone marrow. Our findings underscore the importance of Pyk2 signaling inhibition as a key regulator of bone remodeling, offering promising prospects for the development of novel osteoporosis therapies.
Project description:Cancer stem cells (CSCs) are implicated in tumor initiation, metastasis and drug resistance, and are considered as attractive targets for cancer therapy. We identified a clinically relevant signaling nexus mediated by PYK2 and its impact on stemness in triple negative breast cancer (TNBC). PYK2 depletion in multiple mesenchymal TNBC cell lines markedly reduced the expression of PKCα and AXL proteins and reduced the number of mammosphere-forming cells and cells harboring CSCs characteristic markers. PYK2 and PKCα cooperate at a convergence point of multiple stemness-inducing pathways to regulate AXL levels and concomitantly the levels/activation of key transcription factors implicated in stemness including STAT3, TAZ, FRA1 and SMAD3 as well as the pluripotent transcription factors Nanog and Oct4, and in-turn affect their target genes. Targeting the AXL-PYK2-PKCα circuit could be a promising strategy to eliminate CSCs in TNBC and possibly overcome drug resistance.
Project description:We demonstrated that Pyk2 is a novel fear memory suppressor molecule and Pyk2 null mice provide a model for understanding fear-related disorders.
Project description:We demonstrated that Pyk2 is a novel fear memory suppressor molecule and Pyk2 null mice provide a model for understanding fear-related disorders.
Project description:Macrophage infiltration in mammary tumors is associated with enhanced tumor progression, metastasis, and poor clinical outcome, and considered as target for therapeutic intervention. Here we used different genetic mouse models and show that ablation of the tyrosine kinase PYK2, either in breast cancer cells, only in the tumor microenvironment, or both, markedly reduced the number of infiltrating tumor macrophages and concomitantly inhibited tumor angiogenesis and tumor growth. Strikingly, PYK2 depletion only in macrophages was sufficient to induce similar effects. These phenotypic changes were associated with reduced monocyte recruitment and a substantial decrease in tumor-associated macrophages (TAMs). Mechanistically, we show that PYK2 mediates mutual communication between breast cancer cells and macrophages through critical effects on key receptor signaling. Specifically, PYK2 ablation inhibited Notch1 signaling and consequently reduced CCL2 secretion by breast cancer cells, and concurrently reduced the levels of CCR2, CXCR4, IL4R, and Stat6 activation in macrophages. These bidirectional effects modulate monocyte recruitment, macrophage polarization and tumor angiogenesis. PYK2 expression is correlated with infiltrated macrophages in breast cancer patients, and its significant effects on macrophage infiltration and their pro-tumorigenic phenotype suggest that PYK2 targeting can be utilized as an effective strategy to modulate TAMs and possibly sensitize breast cancer to immunotherapy.
Project description:To investigate the specificity of Defactinib on IRF5 target genes we compare LPS-induced transcriptomes in WT and IRF5 KO BMDMs treated with either Defactinib or vehicle. Macrophage transcriptomic signature under PYK2 inhibition phenocopied IRF5 deficiency
Project description:Pyk2 is a multidomain non-receptor tyrosine kinase that undergoes a complex, multi-stage activation process. Ca2+-flux induces conformational rearrangements that relieve autoinhibitory FERM domain interactions. The kinase domain phosphorylates a key linker residue to recruit Src kinase. Pyk2 and Src mutually phosphorylate activation loop residues to confer full activation. While the mechanisms of autoinhibition are established, the conformational dynamics associated with autophosphorylation and Src recruitment remain unclear. Here, we employ hydrogen/deuterium exchange mass spectrometry (HDX-MS) to map the conformational changes associated with Src-mediated activation segment phosphorylation in a Pyk2 construct encompassing FERM and kinase domains (residues 20-692). Results reveal increased dynamics at regulatory interfaces spanning FERM and kinase domains. Phosphorylation of the activation segment stabilizes two antiparallel beta strands linking activation and catalytic loops. Increased dynamics of the C-terminal end of the activation loop propagate to the F-helix, explaining how phosphorylation prevents reversion to the autoinhibitory FERM interaction. HDX-guided site-directed mutagenesis and kinase activity profiling establish a mechanism for phosphorylation-induced active site sculpting to confer high activity.