Networks of signal transducers determine the conversion of environmental cues into cellular actions. Among the main players in these networks are protein kinases, which can acutely and reversibly modify protein functions to influence cellular events. One group of kinases, the protein kinase C (PKC) family, have been increasingly implicated in the organization of signal propagation, particularly in the spatial distribution of signals. Examples of where and how various PKC isoforms direct this tier of signal organization are becoming more evident.

SUMMARY Bladder cancer incurs a higher lifetime treatment cost than other cancers due to frequent recurrence of non-invasive disease. Improved prognostic biomarkers and localised therapy are needed for this large patient group. We defined two major genomic subtypes of primary stage Ta tumors that showed differential risk of recurrence. The higher risk subtype was characterised by loss of 9q including TSC1, increased KI67 labelling index, upregulated glycolysis, DNA repair, mTORC1 signaling, features of the unfolded protein response and altered cholesterol homeostasis. Comparison with muscle-invasive bladder cancer mutation profiles revealed lower overall mutation rates and more frequent mutations in RHOB and chromatin modifier genes. More mutations in the histone-lysine demethylase KDM6A were present in non-invasive tumors from females than males.

Highlights d Fast-moving cells in 3D matrix establish low membrane tension at the rear d Caveolae form in response to low membrane tension and recruit the GEF Ect2 d Ect2 activates RhoA to promote F-actin organization and rear retraction d Positive feedback between membrane tension and contractility reinforces retraction

The cell cycle is exquisitely controlled by multiple sequential regulatory inputs to ensure fidelity. Here we demonstrate that the final step in division, the physical separation of daughter cells, is controlled by a member of the PKC gene superfamily. Specifically, we have identified three phosphorylation sites within PKCepsilon that control its association with 14-3-3. These phosphorylations are executed by p38 MAP kinase (Ser 350), GSK3 (Ser 346) and PKC itself (Ser 368). Integration of these signals is essential during mitosis because mutations that prevent phosphorylation of PKCepsilon and/or PKCepsilon binding to 14-3-3 also cause defects in the completion of cytokinesis. Using chemical genetic and dominant-negative approaches it is shown that selective inhibition of PKCepsilon halts cells at the final stages of separation. This arrest is associated with persistent RhoA activation at the midbody and a delay in actomyosin ring dissociation. This study therefore identifies a new regulatory mechanism that controls exit from cytokinesis, which has implications for carcinogenesis.

The protein kinase C (PKC) Ser/Thr kinases account for approximately 2% of the human kinome and regulate diverse cellular behaviors. PKC catalytic activity requires priming phosphorylations at three conserved sites within the kinase domain. Here we demonstrate that priming of PKC is dependent on the conformation of the nucleotide binding pocket but not on its intrinsic kinase activity. Inactive ATP binding site mutants are unprimed, but they become phosphorylated upon occupancy of the ATP binding pocket with inhibitors of PKC. We have exploited this property to screen for PKC inhibitors in vivo. Further, we generated a distinct class of kinase-inactive mutants that maintain the integrity of the ATP binding pocket; such mutants are constitutively primed and functionally distinct from ATP binding site mutants. These data demonstrate that autophosphorylation is not required for PKC priming and show how ATP pocket occupation can enable a kinase to mature as well as function.