Elucidation of the evolutionary expansion of phosphorylation signaling networks using comparative phosphomotif analysis

Comprehensive Pan-Cancer Analysis of GINS2 for Human Tumour Prognosis and as an Immunological Biomarker

BACKGROUND

In recent years, more and more reports have shown that GINS complex subunit 2 (GINS2) plays an important role in the occurrence and progression of tumours. However, there is a lack of comprehensive and systematic research on its prognostic and immune effects in pan-cancer. Therefore, this study is aimed at investigating the prognostic value and immune-related role of GINS2 in human tumours and providing a comprehensive understanding of its carcinogenic mechanism in pan-cancer.

METHODS

We investigated different databases, including TIMER, TCGA, GTEX, CPTAC, GEPIA, and SangerBox. The study was carried out on the expression and prognosis of GINS2 in human tumours, immune infiltration and microenvironment, immune checkpoints, neoantigens, tumour mutational burden, microsatellite instability, mismatch repair (MMR) genes, methylation, cancer-associated fibroblasts (CAFs), and enrichment analysis of gene set.

RESULTS

GINS2 plays a potential carcinogenic role in various human tumours through mRNA and protein levels. It is highly expressed in most cancers, and its expression is significantly correlated with tumour prognosis. In addition, the expression of GINS2 is associated with immune microenvironment and immune infiltration, especially in brain lower-grade glioma, lung squamous cell carcinoma, TGCT, breast invasive carcinoma, and glioblastoma multiforme. At the same time, GINS2 is related to immune neoantigens and the expression profiles of immune checkpoint genes in pan-cancer. It also affects the expression of DNA MMR genes and methyltransferase in pan-cancer. Finally, the correlation between GINS2 and CAF abundance in most tumours was studied, and an enrichment analysis of GINS2 and its related proteins was also carried out.

CONCLUSION

This is the first study on GINS2 as a prognostic and immune mechanism in pan-cancer. GINS2 may be a valuable prognostic immunological biomarker of pan-cancer. This paper provides a relatively comprehensive understanding on the correlation of GINS2 with pan-cancer.

Evolutionary Divergence of Phosphorylation to Regulate Interactive Protein Networks in Lower and Higher Species

The phosphorylation of proteins affects their functions in extensively documented circumstances. However, the role of phosphorylation in many interactive networks of proteins remains very elusive due to the experimental limits of exploring the transient interaction in a large complex of assembled proteins induced by stimulation. Previous studies have suggested that phosphorylation is a recent evolutionary process that differently regulates ortholog proteins in numerous lineages of living organisms to create new functions. Despite the fact that numerous phospho-proteins have been compared between species, little is known about the organization of the full phospho-proteome, the role of phosphorylation to orchestrate large interactive networks of proteins, and the intertwined phospho-landscape in these networks. In this report, we aimed to investigate the acquired role of phosphate addition in the phenomenon of protein networking in different orders of living organisms. Our data highlighted the acquired status of phosphorylation in organizing large, connected assemblages in Homo sapiens. The protein networking guided by phosphorylation turned out to be prominent in humans, chaotic in yeast, and weak in flies. Furthermore, the molecular functions of GO annotation enrichment regulated by phosphorylation were found to be drastically different between flies, yeast, and humans, suggesting an evolutionary drift specific to each species.

Nuclear Prospero allows one-division potential to neural precursors and post-mitotic status to neurons via opposite regulation of Cyclin E

In Drosophila embryonic CNS, the multipotential stem cells called neuroblasts (NBs) divide by self-renewing asymmetric division and generate bipotential precursors called ganglion mother cells (GMCs). GMCs divide only once to generate two distinct post-mitotic neurons. The genes and the pathways that confer a single division potential to precursor cells or how neurons become post-mitotic are unknown. It has been suggested that the homeodomain protein Prospero (Pros) when localized to the nucleus, limits the stem-cell potential of precursors. Here we show that nuclear Prospero is phosphorylated, where it binds to chromatin. In NB lineages such as MP2, or GMC lineages such as GMC4-2a, Pros allows the one-division potential, as well as the post-mitotic status of progeny neurons. These events are mediated by augmenting the expression of Cyclin E in the precursor and repressing the expression in post-mitotic neurons. Thus, in the absence of Pros, Cyclin E is downregulated in the MP2 cell. Consequently, MP2 fails to divide, instead, it differentiates into one of the two progeny neurons. In progeny cells, Pros reverses its role and augments the downregulation of Cyclin E, allowing neurons to exit the cell cycle. Thus, in older pros mutant embryos Cyclin E is upregulated in progeny cells. These results elucidate a long-standing problem of division potential of precursors and post-mitotic status of progeny cells and how fine-tuning cyclin E expression in the opposite direction controls these fundamental cellular events. This work also sheds light on the post-translational modification of Pros that determines its cytoplasmic versus nuclear localization.

Gaining Insights into the Function of Post-Translational Protein Modification Using Genome Engineering and Molecular Cell Biology

Modifications by kinases are a fast and reversible mechanism to diversify the function of the targeted proteins. The OCT4 transcription factor is essential for preimplantation development and pluripotency of embryonic stem cells (ESC), and its activity is tightly regulated by post-transcriptional modifications. Several phosphorylation sites have been identified by systemic approaches and their functions proposed. Here, we combined molecular and cellular biology with CRISPR/Cas9-mediated genome engineering to pinpoint the function of serine 12 of OCT4 in ESCs. Using chemical inhibitors and an antibody specific to OCT4 phosphorylated on S12, we identified cyclin-dependent kinase (CDK) 7 as upstream kinase. Surprisingly, generation of isogenic mESCs that endogenously ablate S12 revealed no effects on pluripotency and self-renewal, potentially due to compensation by other phosphorylation events. Our approach reveals that modification of distinct amino acids by precise genome engineering can help to clarify the functions of post-translational modifications on proteins encoded by essential gene in an endogenous context.

Large-scale analysis of the evolutionary histories of phosphorylation motifs in the human genome

Background

Protein phosphorylation is a post-translational modification that is essential for a wide range of eukaryotic physiological processes, such as transcription, cytoskeletal regulation, cell metabolism, and signal transduction. Although more than 200,000 phosphorylation sites have been reported in the human genome, the physiological roles of most remain unknown. In this study, we provide some useful datasets for the assessment of functional phosphorylation signaling using a comparative genome analysis of phosphorylation motifs.

Findings

We described the evolutionary patterns of conservation of these and comparative genomic data for 93,101 phosphosites and 1,003,756 potential phosphosites in human phosphomotifs, using 178 phosphomotifs identified in a previous study that occupied 69% of known phosphosites in public databases. Comparative genomic analyses were performed using genomes from nine species from yeast to humans. Here we provide an overview of the evolutionary patterns of phosphomotif acquisition and indicate the dependence on motif structures. Using the data from our previous study, we describe the interaction networks of phosphoproteins, identify the kinase substrates associated with phosphoproteins, and perform gene ontology enrichment analyses. In addition, we show how this dataset can help to elucidate the function of phosphomotifs.

Conclusions

Our characterizations of motif structures and assessments of evolutionary conservation of phosphosites reveal physiological roles of unreported phosphosites. Thus, interactions between protein groups that share motifs are likely to be helpful for inferring kinase-substrate interaction networks. Our computational methods can be used to elucidate the relationships between phosphorylation signaling and cellular functions.

Electronic supplementary material

The online version of this article (doi:10.1186/s13742-015-0057-6) contains supplementary material, which is available to authorized users.