Dataset Information

Relative Expression Levels Rather Than Specific Activity Plays the Major Role in Determining In Vivo AKT Isoform Substrate Specificity.

ABSTRACT: The AKT protooncogene mediates many cellular processes involved in normal development and disease states such as cancer. The three structurally similar isoforms: AKT1, AKT2, and AKT3 exhibit both functional redundancy and isoform-specific functions; however the basis for their differential signalling remains unclear. Here we show that in vitro, purified AKT3 is ?47-fold more active than AKT1 at phosphorylating peptide and protein substrates. Despite these marked variations in specific activity between the individual isoforms, a comprehensive analysis of phosphorylation of validated AKT substrates indicated only subtle differences in signalling via individual isoforms in vivo. Therefore, we hypothesise, at least in this model system, that relative tissue/cellular abundance, rather than specific activity, plays the dominant role in determining AKT substrate specificity in situ.

SUBMITTER: Lee RS

PROVIDER: S-EPMC3160084 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Relative Expression Levels Rather Than Specific Activity Plays the Major Role in Determining In Vivo AKT Isoform Substrate Specificity.

Lee Rachel S RS House Colin M CM Cristiano Briony E BE Hannan Ross D RD Pearson Richard B RB Hannan Katherine M KM

Enzyme research 20110822

The AKT protooncogene mediates many cellular processes involved in normal development and disease states such as cancer. The three structurally similar isoforms: AKT1, AKT2, and AKT3 exhibit both functional redundancy and isoform-specific functions; however the basis for their differential signalling remains unclear. Here we show that in vitro, purified AKT3 is ∼47-fold more active than AKT1 at phosphorylating peptide and protein substrates. Despite these marked variations in specific activity b ...[more]

PMID: 21869924

Similar Datasets

Project description:Background: PIK3CA mutations are observed in >30% of breast cancers, which are more common in estrogen receptor (ERÎ±)-positive breast cancer compared with ERÎ±-negative breast cancer. AKT1, 2, and 3 isoforms, major isoforms downstream of PI3K, modulate ERÎ± activity. It is unknown whether PIK3CA mutation leads to preferential activation of specific AKT isoforms with an ability to modulate ERÎ± function. Methods: Gene expression arrays were performed on parental, AKT1 knockdown or AKT2 knockdown MCF-7 breast cancer cells with or without estradiol treatment for three hours. Results: AKT1 had a dominant role in ERÎ±:estradiol-dependent gene expression and proliferation. We have identified a unique gene expression signature that is dependent on ERÎ±, estradiol, AKT1 and the pioneer factor FOXA1. Overexpression of this signature was associated with better outcome in patients with ERÎ±-positive breast cancer. In contrast, AKT2 controlled global gene expression. Cells were maintained in phenol red free MEM with 5% charcoal dextran treated fetal calf serum for four days and then treated with ethanol or 0.1 nM estradiol for three hours. RNA was prepared using RNeasy kit (Qiagen, Valencia, CA, USA) Microarray with biological triplicates was performed using Illumina HumanHT-12 V4 expression beadchip. Genes that showed statistically insignificant signals in majority of samples were removed from the microarray data, and only those probes that showed statistically significant signal in at least half of samples of at least one group were retained. The probe level data was then collapsed to gene level data by retaining only the probes, which showed a maximal coefficient of variation across all samples. The data was imported into partek genomics suite for differential expression analysis. ANOVA analysis was performed to identify genes differentially expressed between AKT1KD vs. pLKO, AKT2KD vs. pLKO, and AKT1KD vs. AKT2KD groups. Stratagene Universal Human Reference RNA (Illumina Catalog # 740000) was used as quality control specimen

Dataset Information

Relative Expression Levels Rather Than Specific Activity Plays the Major Role in Determining In Vivo AKT Isoform Substrate Specificity.

Publications

Relative Expression Levels Rather Than Specific Activity Plays the Major Role in Determining In Vivo AKT Isoform Substrate Specificity.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets