PI3Kγ

PI3Kγ is a Class I PI3K isoform that generates PIP₃ and supports leukocyte signaling during inflammation^[1]. Mechanistically, PI3Kγ acts downstream of GPCRs, where p110γ couples with regulatory subunits to control chemoattractant-driven signaling^[2]. In inflammatory models, PI3Kγ-null neutrophils show impaired PIP₃ production, Akt activation, respiratory burst, and motility, while macrophages show reduced chemotactic migration and defective accumulation in septic peritonitis^[3]. In cancer models, macrophage PI3Kγ controls a switch between immune stimulation and immune suppression through Akt/mTOR, NFκB, and C/EBPβ signaling^[4]. Compared with related isoforms, PI3Kγ is the only Class IB PI3K catalytic isoform, whereas PI3Kα, PI3Kβ, and PI3Kδ belong to Class IA^[5]. This distinction supports isoform-focused experimental design, especially when separating myeloid-cell PI3Kγ biology from lymphocyte-enriched PI3Kδ signaling^[5][6]. For research applications, selective PI3Kγ inhibition reshaped suppressive myeloid cells and improved checkpoint blockade responses in mouse tumor models^[7]. Dual PI3Kδ/PI3Kγ inhibitors such as IPI-145 provide tools for testing combined innate and adaptive immune PI3K signaling in biochemical, cellular, and in vivo assays^[8].