Biology subjects

Lau, H.-T.

Publications and source records attributed to Lau, H.-T..

4 recordsLinked to original sources

bioRxiv2021

Displacement of PKA catalytic subunit from AKAP signaling islands drives pathology in Cushing's syndrome

Mutations in the catalytic subunit of protein kinase A (PKAc) drive the stress hormone disorder adrenal Cushings syndrome. Here we define mechanisms of action for the PKAc-L205R and W196R variants. Both Cushings mutants are excluded from A kinase anchoring protein (AKAP) signaling islands and consequently diffuse throughout the cell. Kinase-dead experiments show that PKA activity is required for cortisol hypersecretion. However, kinase activation is not sufficient, as only cAMP analog drugs that displace native PKAc from AKAPs enhance cortisol release. Rescue experiments that incorporate mutant PKAc into AKAP signaling islands abolish cortisol overproduction, indicating that kinase anchoring restores normal endocrine function. Phosphoproteomics show that PKAc-L205R and W196R engage different mitogenic signaling pathways. ERK activity is elevated in adrenal-specific PKAc-W196R knock-in mice. Conversely, PKAc-L205R attenuates Hippo signaling, thereby upregulating the YAP/TAZ transcriptional co-activators. Thus, aberrant localization of each Cushings variant promotes the transmission of a distinct downstream pathogenic signal.

molecular biology↗

bioRxiv2021

Multiplexed profiling of kinase interactomes quantifies cellular network plasticity

Cells utilize protein-protein interaction (PPI) networks to receive, transduce, and respond to stimuli. Interaction network rewiring drives devastating diseases like cancers, making PPIs attractive targets for pharmacological intervention. Kinases are druggable nodes in PPI networks but high-throughput proteomics approaches to quantify disease-associated kinome PPI rewiring are lacking. We introduce kinobead competition and correlation analysis (Ki-CCA), a chemoproteomics approach to simultaneously map hundreds of endogenous kinase PPIs. We identified 2,305 PPIs of 300 kinases across 18 diverse cancer lines, quantifying the high plasticity of interaction networks between cancer types, signaling, and phenotypic states; this database of dynamic kinome PPIs provides deep insights into cancer cell signaling. We discovered an AAK1 complex promoting epithelial-mesenchymal transition and drug resistance, and depleting its components sensitized cells to targeted therapy. Ki-CCA enables rapid and highly multiplexed mapping of kinome PPIs in native cell and tissue lysates, without epitope tagged baits, protein labeling, or antibodies.

biochemistry↗

bioRxiv2019

Kinome-centric pharmacoproteomics identifies signaling pathways underlying cellular responses to targeted cancer drugs

ABSTRACTKinase-dependent signaling networks are frequently dysregulated in cancer, driving disease progression. While kinase inhibition has become an important therapeutic approach many cancers resist drug treatment. Therefore, we need both reliable biomarkers that predict drug responses and new targets to overcome drug resistance. Determining the kinase(s) that control cancer progression in individual cancers can pose a significant challenge. Genomics has identified important, yet limited numbers of kinase driver mutations. Transcriptomics can quantify aberrant gene expression, but it cannot measure the protein phosphorylation that regulates kinase-dependent signaling network activity. Proteomics measures protein expression and phosphorylation and, therefore, quantifies aberrant signaling network activity directly. We developed a kinome-centric pharmacoproteomics platform to study signaling pathways that determine cancer drug response. Using hepatocellular carcinoma (HCC) as our model, we determined kinome activity with kinobead/LC-MS profiling, and screened 299 kinase inhibitors for growth inhibition. Integrating kinome activity with drug responses, we obtained a comprehensive database of predictive biomarkers, and kinase targets that promote drug sensitivity and resistance. Our dataset specified pathway-based biomarkers for the clinical HCC drugs sorafenib, regorafenib and lenvatinib, and we found these biomarkers enriched in human HCC specimens. Strikingly, our database also revealed signaling pathways that promote HCC cell epithelial-mesenchymal transition (EMT) and drug resistance, and that NUAK1 and NUAK2 regulate these pathways. Inhibition of these kinases reversed the EMT and sensitized HCC cells to kinase inhibition. These results demonstrate that our kinome pharmacoproteomics platform discovers both predictive biomarkers for personalized oncology and novel cancer drug targets.

cancer biology↗

bioRxiv2019

CCDC186 recruits EARP and controls dense-core vesicle cargo sorting by exit

The regulated release of peptide hormones depends on their packaging into dense-core vesicles (DCVs). Two models have been proposed for DCV cargo sorting. The \"sorting by entry\" model proposes that DCV cargos selectively enter nascent DCVs at the trans-Golgi network (TGN). The \"sorting by exit\" model proposes that sorting occurs by the post-TGN removal of non-DCV cargos and retention of mature DCV cargos. Here we show that the coiled-coil protein CCDC186 controls sorting by exit. Ccdc186 KO insulinoma cells secrete less insulin, fail to retain insulin and carboxypeptidase E in mature DCVs at the cell periphery, and fail to remove carboxypeptidase D from immature DCVs. A mutation affecting the endosome-associated recycling protein (EARP) complex causes similar defects in DCV cargo retention and removal. CCDC186 and EARP may act together to control the post-Golgi retention of cargos in mature DCVs.

cell biology↗