Focal adhesion kinase (FAK) as a central regulator of cardiac resident macrophage development and injury response. - focal adhesions are large multiprotein complexes that allow a cell to anchor itself…

Focal adhesion kinase (FAK) as a central regulator of cardiac resident macrophage development and injury response. - focal adhesions are large multiprotein complexes that allow a cell to anchor itself to the surrounding actin cytoskeleton of the extracellular matrix. Previous studies have demonstrated that focal adhesions exist at the interface of cardiac resident macrophages (crms) and the basement membrane of neighboring cardiomyocytes, suggesting an unexpected mechanosensitive mechanism of immune-cardiomyocyte communication. However, the ways in which cardiac resident macrophages use focal adhesion signaling to regulate their differentiation, localization, and injury-associated effector functions remains undefined. Because cardiac macrophage dysregulation contributes to myocardial inflammation and heart failure progression, understanding these pathways has important implications for cardiovascular disease. I hypothesize that FAK is a central regulator of CRM-CM interactions and contributes to the establishment and function of crms in the developing heart and is essential for activating the reparative effector functions of CRM. To investigate this, i utilized CX3CR1CREERT2; PTK2F/f; ROSA26TDTOMATO mice to delete FAK in crms in vivo. Deletion of FAK in cardiac resident macrophages led to disruption of CRM processes extending from macrophages to cardiomyocytes at baseline, suggesting a requirement for focal adhesion signaling in CRM-cardiomyocyte contact. Acute pressure overload induced via angiotensin II and phenylephrine (angii/PE) infusion resulted in activation of proinflammatory mediators, and chronic overload resulted in decreased left ventricular function measured by echocardiography and worsened the development of cardiac fibrosis in FAK KO mice. These findings suggest that FAK signaling has a protective role during stress. Furthermore, single cell RNA sequencing revealed substantial shifts in monocyte-derived macrophage identities, suggesting a role of FAK in the recruitment and cell fate decisions of monocytes. Future studies will determine how FAK signaling programs CRM identity, localization and contribution to coronary vascular development during embryogenesis (aim 1) and will define the mechanosensitive pathways through which FAK governs CRM activation and monocyte cell fate specification following injury (aim 2). Together these aims will leverage CRM-specific genetic tools, spatial transcriptomics, advanced imaging, and high-resolution single-cell analyses to dissect how loss of mechanotransduction alters both developmental and injury-induced macrophage functions. This work will be the first to establish mechanotransduction as a regulator of CRM biology through an integrated, spatially informed in vivo approach. By defining how crms interpret mechanical cues across developmental and disease contexts, these studies will fill a major GAP in our understanding of immune-cardiomyocyte communication and may reveal new pathways that may be targeted to limit maladaptive inflammation and improve myocardial repair in cardiomyopathy.