Source (MLPCN Center Name): The Scripps Research Institute Molecular Screening Center
Affiliation: The Scripps Research Institute, TSRI
Assay Provider: Ben Cravatt, TSRI
Network: Molecular Library Probe Production Centers Network (MLPCN)
Grant Proposal Number: 1 R01 CA132630 Fast Track
Grant Proposal PI: Ben Cravatt, TSRI
External Assay ID: LYPLA2_INH_POST-PRUN_SUMMARY

Name: Summary of probe development efforts to identify inhibitors of lysophospholipase 2 (LYPLA2).

Description: Reversible protein phosphorylation networks play essential roles in most cellular processes. While over 500 kinases catalyze protein phosphorylation, only two enzymes, PP1 and PP2a, are responsible for >90% of all serine/ threonine phosphatase activity (1). Phosphatases, unlike kinases, achieve substrate specificity through complex subunit assembly and post-translational modifications rather than number. PP2a, for example, typically exists as heterotrimer with diverse subunits that may combinatorially make as many as 70 different holoenzyme assemblies (2). Mutations in several of these PP2a subunits have been identified in human cancers, suggesting that PP2a may act as a tumor suppressor (3). Adding further complexity, several residues of the catalytic subunit of PP2a can be reversibly phosphorylated, and the C-terminal leucine residue can be reversibly methylated (4,5). Protein phosphatase methylesterase 1 (PME-1) is specifically responsible for demethylation of the carboxyl terminus (6).

Methylesterification is thought to control the binding of different subunits to PP2a, but little is known about physiological significance of this post-translational modification in vivo (7). Recently, PME-1 has been identified as a protector of sustained ERK pathway activity in malignant gliomas (8). In order to further elucidate the role of PP2a methylation in vivo, our lab has generated mice that lack PME-1 (PME-1 (-/-) mice) by targeted gene disruption (9). Unfortunately, PME-1 deletion resulted in perinatal lethality, underscoring the importance of PME-1 but hindering our biological studies. Biochemical elucidation of PME-1 and other protein modifiers such as lysophospholipases (LYPLA) would thus greatly benefit from the development of potent and selective chemical inhibitors (10).

Summary of Probe Development Effort:

This probe development effort is focused on the identification of LYPLA2 inhibitors (AID 2177). All AIDs that contain results associated with this project can be found in the "Related Bioassays" section of this Summary AID.

References:

1. Oliver, C. J., Shenolikar, S. (1998). Physiologic importance of protein phosphatase inhibitors. Front. Biosci. 3, D961-972.
2. Janssens, V., Goris, J. (2001). Protein phosphatase 2A: a highly regulated family of serine/threonine phosphatases implicated in cell growth and signalling. Biochem. J. 353, 417-439.
3. Janssens, V., Goris, J., Van Hoof, C. (2005). PP2A: the expected tumor suppressor. Curr. Opin. Genet. Dev. 15, 34-41.
4. Chen, J., Martin, B. L., Brautigan, D. L. (1992). Regulation of protein serine-threonine phosphatase type-2A by tyrosine phosphorylation. Science 257, 1261-1264.
5. Favre, B., Zolnierowicz, S., Turowski, P., Hemmings, B. A. (1994). The catalytic subunit of protein phosphatase 2A is carboxyl-methylated in vivo. J. Biol. Chem. 269, 16311-16317.
6. Lee, J., Chen, Y., Tolstykh, T., Stock, J. (1996). A specific protein carboxyl methylesterase that demethylates phosphoprotein phosphatase 2A in bovine brain. Proc. Natl. Acad. Sci. U. S. A. 93, 6043-6047.
7. Wu, J., Tolstykh, T., Lee, J., Boyd, K., Stock, J. B., Broach, J. R. (2000). Carboxyl methylation of the phosphoprotein phosphatase 2A catalytic subunit promotes its functional association with regulatory subunits in vivo. Embo J. 19, 5672-5681.
8. Puustinen, P., Junttila, M. R., Vanhatupa, S., Sablina, A. A., Hector, M. E., Teittinen, K., Raheem, O., Ketola, K., Lin, S., Kast, J., Haapasalo, H., Hahn, W. C., Westermarck, J. (2009). PME-1 protects extracellular signal-regulated kinase pathway activity from protein phosphatase 2A-mediated inactivation in human malignant glioma. Cancer Res. 69, 2870-2877.
9. Ortega-Gutierrez, S., Leung, D., Ficarro, S., Peters, E. C., Cravatt, B. F. (2008). Targeted disruption of the PME-1 gene causes loss of demethylated PP2A and perinatal lethality in mice. PLoS ONE 3, e2486.
10. Kidd, D., Liu, Y., Cravatt, B. F. (2001). Profiling serine hydrolase activities in complex proteomes. Biochemistry 40, 4005-4015.

Keywords:

Summary, Summary AID, PME-1, protein phosphatase methylesterase 1, PPME-1, protein phosphatase 2a, PP2a, lysophospholipase, LYPLA1, LYPLA2, cancer, fluorescence polarization, activity-based protein profiling, ABPP, fluorophosphonate rhodamine, FP-Rh, antagonist, inhibitor, counterscreen, high throughput screen, HTS, 1536, Scripps, Scripps Florida, The Scripps Research Institute Molecular Screening Center, SRIMSC, Molecular Libraries Probe Production Centers Network, MLPCN.

Details of protocols, compound structures, and results from the original assays can be found in PubChem at the respective AIDs.

A probe development project is underway at the SRIMSC.

Grant Number: 1 R01 CA132630