Reversion of Ras- and Phosphatidylcholine-hydrolyzing Phospholipase C-mediated Transformation of NIH 3T3 Cells by a Dominant Interfering Mutant of Protein Kinase C λ Is Accompanied by the Loss of Constitutive Nuclear Mitogen-activated Protein Kinase/Extracellular Signal-regulated Kinase Activity

Atypical λ/ιPKC Conveys 5-Lipoxygenase/Leukotriene B4-mediated Cross-talk between Phospholipase A2s Regulating NF-κB Activation in Response to Tumor Necrosis Factor-α and Interleukin-1β

“…The generation of HaCaT cells stably expressing the plasmid pBIIX with two copies of an HIV-NF-B sequence cloned upstream of the mouse fos promoter and the Photinus pyralis luciferase coding sequence (31) has been described previously (29). Isolation of NIH-3T3 fibroblasts stably transfected with v-ras or doubly transfected with v-ras-dn/PKC, which was grown in the presence of hygromycin (0.3 mg/ml), has been reported previously (32,33 Assay of cPLA 2 Activity-NIH-3T3 cells were cultured in DMEM with 4.5 g of glucose/liter and 10% FCS to 50% confluency in 6-round multiwell plates and starved in 0.5% FCS-containing DMEM for 24 h. Stimulated NIH-3T3 cells were scraped into lysis buffer (10 mM Hepes, pH 7.5, 0.34 M sucrose, 0.8 mM Triton X-100, 1 mM EDTA, 1 mM EGTA, 10 g/ml leupeptin, 1 mM phenylmethylsulfonyl fluoride, 1 M pepstatin), homogenized by 10 passes through a 26-gauge needle, and centrifuged (14,000 rpm, 10 min, 4°C). For each sample, 70 g of total protein of the supernatant was assayed for cPLA 2 activity using sonicated vesicles of 1-palmitoyl-2-arachidonoyl-sn-glycerol-3-phosphorylcholine (100 M) containing 100,000 cpm of 1-palmitoyl-2-[1-…”

“…Perhaps more probable is that cPLA 2 phosphorylation conveyed by /PKC is brought about in a p38 MAP kinasedependent manner causing phosphorylation on Ser-505 as reported (70,71) and possibly on Ser-727, recently shown to be phosphorylated by the p38 MAP kinase-activated MAP kinase interacting kinase 1 or a closely related kinase (15). MAP kinases are known to be activated downstream of atypical PKCs (33,(72)(73)(74)(75), and the involvement of p38 or p42/44 MAP kinases in TNF-␣/IL-1␤/sPLA 2 /LTB 4 -mediated cPLA 2 activation has recently been suggested (46,63,76,77). Also, p38 MAP kinase and /PKC have been implicated in TNF-␣/IL-1␤-stimulated NF-B activation (37-39, 79 -81).…”

Protein kinase Cι: Human oncogene, prognostic marker and therapeutic target

“…PKCι has also been directly linked to oncogenic Ras signaling (49)(50)(51)(52). Ras can bind and activate aPKCs (53,54) and PKCι has been implicated in oncogenic Ras signaling in fibroblasts (49)(50)(51)55).…”

“…Ras can bind and activate aPKCs (53,54) and PKCι has been implicated in oncogenic Ras signaling in fibroblasts (49)(50)(51)55). PKCι also plays a critical role in oncogenic Ras-mediated transformation in the intestinal epithelium (42).…”

“…Oncogenic Ras can activate atypical PKCs (53,54) and PKCι is required for oncogenic Rasmediated signaling (49)(50)(51). Bcr-Abl transcriptionally regulates PKCι expression through Ras/ Mek-dependent activation of an Elk1 element within the proximal PKCι promoter (71).…”