Regulation of Focal Adhesion Kinase through a Direct Interaction with an Endogenous Inhibitor

Focal Adhesion Regulation as a Strategy against Kidney Fibrosis

Chronic kidney fibrosis poses a significant global health challenge with effective therapeutic strategies remaining elusive. While cell-extracellular matrix (ECM) interactions are known to drive fibrosis progression, the specific role of focal adhesions (FAs) in kidney fibrosis is not fully understood. In this study, we investigated the role of FAs in kidney tubular epithelial cell fibrosis by employing precise nanogold patterning to modulate integrin distribution. We demonstrate that increasing ligand spacing disrupts integrin clustering, thereby inhibiting FA formation and attenuating fibrosis. Importantly, enhanced FA activity is associated with kidney fibrosis in both human disease specimens and murine models. Mechanistically, FAs regulate fibrosis through mechanotransduction pathways, and our in vivo experiments show that suppressing mechanotransduction significantly mitigates kidney fibrosis in mice. These findings highlight the potential of targeting FAs as a therapeutic strategy, offering new insights into clinical intervention in kidney fibrosis.

FAK-LINC01089 negative regulatory loop controls chemoresistance and progression of small cell lung cancer

The focal adhesion kinase (FAK) tyrosine kinase is activated and upregulated in multiple cancer types including small cell lung cancer (SCLC). However, FAK inhibitors have shown limited efficacy in clinical trials for cancer treatment. With the aim of identifying potential therapeutic strategies to inhibit FAK for cancer treatment, we investigated long non-coding RNAs (lncRNAs) that potentially regulate FAK in SCLC. In this study, we identified a long non-coding RNA LINC01089 that binds and inhibits FAK phosphorylation (activation). Expression analysis revealed that LINC01089 was downregulated in SCLC tissues and negatively correlated with chemoresistance and survival in SCLC patients. Functionally, LINC01089 inhibited chemoresistance and progression of SCLC in vitro and in vivo. Mechanistically, LINC01089 inhibits FAK activation by blocking binding with Src and talin kinases, while FAK negatively regulates LINC01089 transcription by activating the ERK signaling pathway to recruit the REST transcription factor. Furthermore, LINC01089-FAK axis mediates the expression of drug resist-related genes by modulating YBX1 phosphorylation, leading to drug resistance in SCLC. Intriguingly, the FAK-LINC01089 interaction depends on the co-occurrence of the novel FAK variant and the non-conserved region of LINC01089 in primates. In Conclusion, our results indicated that LINC01089 may serve as a novel high-efficiency FAK inhibitor and the FAK-LINC01089 axis represents a valuable prognostic biomarker and potential therapeutic target in SCLC.

Focal adhesion kinase coordinates costamere-related JNK signaling with muscle fiber transformation after Achilles tenotomy and tendon reconstruction

Achilles tendon rupture necessitates rapid tendon reattachment to reinstate plantar flexion before affected muscles deteriorate through muscle fiber atrophy and transformation. The implicated process may involve alterations in sarcolemmal sites of myofibril attachment (costameres), which control myofibrillogenesis via a mechano-regulated mechanism through integrin-associated focal adhesion kinase (FAK). We assessed the contribution of FAK to alterations in fiber type composition and expression of costamere-associated structural proteins, the phosphorylation status of Y397-FAK and downstream mTOR/JNK-P70S6K hypertrophy signaling in rat soleus muscle after Achilles tenotomy and tendon repair. Achilles tenotomy induced a profound deterioration of muscle composition 14 days, but not 4 days, following tendon release, comprising specifically increased area percentages of fast type fibers, fibers with internal nuclei, and connective tissue. Concomitantly, expression of costameric proteins FAK and meta-vinculin, and phosphorylation of T421/S424-P70S6K and T183/Y185-JNK was elevated, all of which was mitigated by tendon reattachment immediately after release. Overexpression of FAK in soleus muscle fibers and reattachment corrected the expression of meta- and gamma-vinculin isoforms to the lower levels in mock controls while further enhancing T183/Y185-JNK phosphorylation and levels of FAK C-terminus-related inhibitory proteins. Co-overexpression of the FAK inhibitor, FRNK, lowered FAK-overexpression driven Y397-FAK phosphorylation and T183/Y185-JNK phosphorylation. FAK levels correlated to molecular and cellular hallmarks of fiber degeneration. The findings demarcate the window between 4 and 14 days after tenotomy as costamere-dependent muscle transformation process, and expose that FAK overexpression prevents molecular aspects of the pathology which within the study limitations does not result in the mitigation of muscle fiber degeneration.250 words.

The DWORF micropeptide enhances contractility and prevents heart failure in a mouse model of dilated cardiomyopathy

Calcium (Ca2+) dysregulation is a hallmark of heart failure and is characterized by impaired Ca2+ sequestration into the sarcoplasmic reticulum (SR) by the SR-Ca2+-ATPase (SERCA). We recently discovered a micropeptide named DWORF (DWarf Open Reading Frame) that enhances SERCA activity by displacing phospholamban (PLN), a potent SERCA inhibitor. Here we show that DWORF has a higher apparent binding affinity for SERCA than PLN and that DWORF overexpression mitigates the contractile dysfunction associated with PLN overexpression, substantiating its role as a potent activator of SERCA. Additionally, using a well-characterized mouse model of dilated cardiomyopathy (DCM) due to genetic deletion of the muscle-specific LIM domain protein (MLP), we show that DWORF overexpression restores cardiac function and prevents the pathological remodeling and Ca2+ dysregulation classically exhibited by MLP knockout mice. Our results establish DWORF as a potent activator of SERCA within the heart and as an attractive candidate for a heart failure therapeutic.

Targeting Focal Adhesion Kinase Using Inhibitors of Protein-Protein Interactions

Focal adhesion kinase (FAK) is a cytoplasmic non-receptor protein tyrosine kinase that is overexpressed and activated in many human cancers. FAK transmits signals to a wide range of targets through both kinase-dependant and independent mechanism thereby playing essential roles in cell survival, proliferation, migration and invasion. In the past years, small molecules that inhibit FAK kinase function have been developed and show reduced cancer progression and metastasis in several preclinical models. Clinical trials have been conducted and these molecules display limited adverse effect in patients. FAK contain multiple functional domains and thus exhibit both important scaffolding functions. In this review, we describe the major FAK interactions relevant in cancer signalling and discuss how such knowledge provide rational for the development of Protein-Protein Interactions (PPI) inhibitors.

Endogenous Control Mechanisms of FAK and PYK2 and Their Relevance to Cancer Development

Focal adhesion kinase (FAK) and its close paralogue, proline-rich tyrosine kinase 2 (PYK2), are key regulators of aggressive spreading and metastasis of cancer cells. While targeted small-molecule inhibitors of FAK and PYK2 have been found to have promising antitumor activity, their clinical long-term efficacy may be undermined by the strong capacity of cancer cells to evade anti-kinase drugs. In healthy cells, the expression and/or function of FAK and PYK2 is tightly controlled via modulation of gene expression, competing alternatively spliced forms, non-coding RNAs, and proteins that directly or indirectly affect kinase activation or protein stability. The molecular factors involved in this control are frequently deregulated in cancer cells. Here, we review the endogenous mechanisms controlling FAK and PYK2, and with particular focus on how these mechanisms could inspire or improve anticancer therapies.