USP30 sets a trigger threshold for PINK1–PARKIN amplification of mitochondrial ubiquitylation

The mitochondrial deubiquitylase USP30 negatively regulates the selective autophagy of damaged mitochondria. We present the characterisation of an N-cyano pyrrolidine compound, FT3967385, with high selectivity for USP30. We demonstrate that ubiquitylation of TOM20, a component of the outer mitochondrial membrane import machinery, represents a robust biomarker for both USP30 loss and inhibition. A proteomics analysis, on a SHSY5Y neuroblastoma cell line model, directly compares the effects of genetic loss of USP30 with chemical inhibition. We have thereby identified a subset of ubiquitylation events consequent to mitochondrial depolarisation that are USP30 sensitive. Within responsive elements of the ubiquitylome, several components of the outer mitochondrial membrane transport (TOM) complex are prominent. Thus, our data support a model whereby USP30 can regulate the availability of ubiquitin at the specific site of mitochondrial PINK1 accumulation following membrane depolarisation. USP30 deubiquitylation of TOM complex components dampens the trigger for the Parkin-dependent amplification of mitochondrial ubiquitylation leading to mitophagy. Accordingly, PINK1 generation of phospho-Ser65 ubiquitin proceeds more rapidly in cells either lacking USP30 or subject to USP30 inhibition

Substrate-mimetic AKT inhibitor

Disclosed herein is a species of peptide and non-peptide inhibitors of Akt, an oncogenic protein. Beginning with a residue of Akt target substrate GSK-3, the functional domains of the GSK-3 residue were characterized. Functionally homologous non-peptide groups were substituted for the amino acids of the GSK-3 creating a hybrid peptide-non-peptide and non-peptide compounds capable of binding to Akt. The non-peptide compounds show increased stability and rigidity compared to peptide counterparts and are less susceptible to degradation. The bound non-peptide compounds exhibit an inhibitory effect on Akt, similar to peptide-based Akt inhibitors

Substrate-mimetic Akt inhibitor

Disclosed herein is a species of peptide and non-peptide inhibitors of Akt, an oncogenic protein. Beginning with a residue of Akt target substrate GSK-3, the functional domains of the GSK-3 residue were characterized. Functionally homologous non-peptide groups were substituted for the amino acids of the GSK-3 creating a hybrid peptide-non-peptide and non-peptide compounds capable of binding to Akt. The non-peptide compounds show increased stability and rigidity compared to peptide counterparts and are less susceptible to degradation. The bound non-peptide compounds exhibit an inhibitory effect on Akt, similar to peptide-based Akt inhibitors

Substrate-mimetic Akt inhibitor

Disclosed herein is a species of peptide and non-peptide inhibitors of Akt, an oncogenic protein. Beginning with a residue of Akt target substrate GSK-3, the functional domains of the GSK-3 residue were characterized. Functionally homologous non-peptide groups were substituted for the amino acids of the GSK-3 creating a hybrid peptide-non-peptide and non-peptide compounds capable of binding to Akt. The non-peptide compounds show increased stability and rigidity compared to peptide counterparts and are less susceptible to degradation. The bound non-peptide compounds exhibit an inhibitory effect on Akt, similar to peptide-based Akt inhibitors

Non-peptidic substrate-mimetic inhibitors of Akt as potential anti-cancer agents.

Akt has emerged as a critical target for the development of anti-cancer therapies. It has been found to be amplified, overexpressed, or constitutively activated in numerous human malignancies with oncogenesis derived from the simultaneous promotion of cell survival and suppression of apoptosis. A valuable alternative to the more common ATP-mimetic based chemotherapies is a substrate-mimetic approach, which has the potential advantage of inherent specificity of the substrate-binding pocket. In this paper we present the development of high affinity non-peptidic, substrate-mimetic inhibitors based on the minimum GSK3beta substrate sequence. Optimization of initial peptidic leads resulted in the development of several classes of small molecule inhibitors, which have comparable potency to the initial peptidomimetics, while eliminating the remaining amino acid residues. We have identified the first non-peptidic substrate-mimetic lead inhibitors of Akt 29a-b, which have affinities of 17 and 12 microM, respectively. This strategy has potential to provide a useful set of molecular probes to assist in the validation of Akt as a potential target for anti-cancer drug design

Asymmetric phosphorylation through catalytic P(III) phosphoramidite transfer: Enantioselective synthesis of d-myo-inositol-6-phosphate

Despite the ubiquitous use of phosphoramidite chemistry in the synthesis of biophosphates, catalytic asymmetric phosphoramidite transfer remains largely unexplored for phosphate ester synthesis. We have discovered that a tetrazole-functionalized peptide, in the presence of 10-Å molecular sieves, functions as an enantioselective catalyst for phosphite transfer. This chemistry in turn has been used as the key step in a streamlined synthesis of myo-inositol-6-phosphate. Mechanistic insights implicate phosphate as a directing group for a highly selective kinetic resolution of a protected inositol monophosphate. This work represents a distinct and efficient method for the selective catalytic phosphorylation of natural products