p110γ and p110δ isoforms of phosphoinositide 3-kinase differentially regulate natural killer cell migration in health and disease

Abstract

The mechanisms that regulate NK cell trafficking are unclear. Phosphoinositide-3 kinases (PI3K) control cell motility and the p110␥ and p110␦ isoforms are mostly expressed in leukocytes, where they transduce signals downstream of G protein coupled receptors (GPCR) or tyrosine kinase receptors, respectively. Here, we set out to determine the relative contribution of p110␥ and p110␦ to NK cell migration in mice. Using a combination of single-cell imaging analysis of transgenic cells reporting on PI3K activity in real time and small molecule inhibitors of p110␥ and p110␦, we show here that the tyrosine-kinase coupled p110␦ is linked to GPCR signaling and, depending on the GPCR, may even be preferentially activated over p110␥. Using gene-targeted mice, we showed that both isoforms were essential for NK cell chemotaxis to CXCL12 and to CCL3 and, in vivo, for normal NK cell migration during pregnancy and to the inflamed peritoneum. By contrast, only p110␦ was indispensable for chemotaxis to S1P and CXCL10 and for NK cell distribution throughout lymphoid and nonlymphoid tissues and for extravasation to tumors. These results implicate p110␦ downstream of GPCRs in NK cells and highlight its nonredundant role as a key regulator of NK cell trafficking in health and disease.cell signaling ͉ cell trafficking ͉ innate immunity N K cells develop primarily in the bone marrow, thymus and lymph nodes and are distributed in lymphoid tissues, and in many organs throughout the body, including uterus, liver, lungs, intestine and peritoneum. Resident and recruited NK cells play important roles in reproduction and in immunological surveillance (1-3), and therefore migration is an important aspect of NK cell biology. Lymphocyte migration is organized by selectins, chemokines and integrins (4) and although some of the factors regulating NK cell trafficking are emerging, the picture is incomplete (1, 5). For example, L-selectin is indispensible for NK cell migration to lymph nodes (6), and some chemokines and chemokine receptors have been identified that orchestrate NK cell egression from the bone marrow (7), migration to the decidua (2), sites of inflammation (3), activated lymph nodes (8), and tumors (9-10). Recently, the GPCR sphingosine 1-phosphate receptor 5 (S1P 5 ) has been identified as a key regulator of NK cell distribution (11). These studies indicate that the mechanisms that regulate NK cell trafficking are distinct from those that regulate the trafficking of other lymphocytes and therefore, in view of the promise of pharmacological inhibitors of leukocyte trafficking to treat disease (12), it is important to know how target molecules regulate trafficking of all leukocyte subsets.Phosphoinositide 3-kinases (PI3Ks) generate lipid second messengers that control disparate aspects of cell biology, including growth, survival, metabolism and motility (13) and are prominent pharmacological targets (14, 15). Class I PI3Ks are the most thoroughly studied in mammalian cells and are composed of 2 subclasses, which include 4 catalytic iso...

Targeting the phosphoinositide 3-kinase pathway in hematologic malignancies

“…10 Notably, p110d and p110g are exclusively expressed in hematopoietic cells, whereas the α and β isoforms are ubiquitous. 1,11,12 Class IA PI3Ks are activated by direct interaction with RTKs, non-RTKs, G-protein coupled receptors (GPCRs), and Ras, whereas class IB enzymes are activated by GPCRs and Ras. [13][14][15][16] The regulatory subunits mediate membrane localization, receptor binding, and activation, whereas the catalytic subunit phosphorylates phosphatidylinositol-4,5-bisphosphate (PI-4,5-P 2 ) to yield phosphatidylinositol-3,4,5-trisphosphate (PIP 3 ).…”

“…1,93 PI3Kd and PI3Kg are mainly expressed in hematopoietic cells. 11 Blocking the activity of specific isoforms that are crucial for survival could theoretically provide complete target inhibition at tolerable doses and maximize the therapeutic index of this drug class.…”

PTEN regulates natural killer cell trafficking in vivo

“…A previous report has demonstrated that NK cell deletion of the p110δ isoform of PI3K also results in the defective trafficking of NK cells, suggesting that the balance of PI3K signals is critical for normal NK cell distribution (32). However, these PI3K-deficient NK cells are less responsive to numerous chemokines acting through G αi , including CXCL12, CCL3, CXCL10, and S1P.…”

“…CXCL12 and VCAM-1 both have important roles in the retention of BM NK cells by binding to CXCR4 and VLA-4 on NK cells, respectively (4,8). Engagement of these receptors can trigger activation of the PI3K pathway (32,33). To test whether insufficient chemokine or integrin retention signals could explain the loss of BM NK cells, we treated PTEN…”

Inhibition of PI3K Signaling Spurs New Therapeutic Opportunities in Inflammatory/Autoimmune Diseases and Hematological Malignancies

“…Likewise, both PI3K␥ and PI3K␦ are necessary for natural killer (NK) cell migration to inflamed tissues and the uterus during early pregnancy in vivo and chemotaxis to CXCL12 and CCL3 in vitro. In contrast, PI3K␦ alone was required for NK cell distribution in steady state as well as for trafficking to lymphomas and for chemotaxis to S1P and CXCL10 in vitro (Saudemont et al, 2009). Other studies in murine models have shown that in vitro, both PI3K␦ and PI3K␥ are required for Fc␥RI-driven mast cell degranulation; in vivo, PI3K␥ (but not PI3K␦) is dispensable for allergic responsiveness (Laffargue et al, 2002;Ali et al, 2004Ali et al, , 2008Kitaura et al, 2005).…”