PDRG1 at the interface between intermediary metabolism and oncogenesis

PDRG1 is essential for early plant development as a component of the prefoldin-like complex

p53 AND DNA DAMAGE-REGULATED GENE1 (PDRG1) is part of the prefoldin-like complex (PFDLc) in plants and animals. Whether PDRG1 acts primarily as a subunit of PFDLc or as an independent subunit is not known in any eukaryote. Here, we show that impairment of PDRG1 activity in Arabidopsis thaliana leads to embryonic lethality, as is the case for the other prefoldin-like proteins UXT and AtURI. The subunits of PFDLc are the main interactors of PDRG1 in vivo, and the interactomes of PDRG1, UXT, and AtURI show strong overlaps, including subunits of nuclear RNA polymerases and various complexes of the spliceosome. Our results show that PDRG1 plays an essential role in Arabidopsis mainly as a subunit of PFDLc.

Posttranslational Regulation of Mammalian Sulfur Amino Acid Metabolism

Metabolism of the mammalian proteinogenic sulfur amino acids methionine and cysteine includes the methionine cycle and reverse transsulfuration pathway, establishing many connections with other important metabolic routes. The main source of these amino acids is the diet, which also provides B vitamins required as cofactors for several enzymes of the metabolism of these amino acids. While methionine is considered an essential amino acid, cysteine can be produced from methionine in a series of reactions that also generate homocysteine, a non-proteinogenic amino acid linking reverse transsulfuration with the methionine and folate cycles. These pathways produce key metabolites that participate in synthesizing a large variety of compounds and important regulatory processes (e.g., epigenetic methylations). The impairment of sulfur amino acid metabolism manifests in many pathological processes, mostly correlated with oxidative stress and alterations in glutathione levels that also depend on this part of the cellular metabolism. This review analyzes the current knowledge on the posttranslational regulation of mammalian sulfur amino acid metabolism, highlighting the large number of modification sites reported through high-throughput studies and the surprisingly limited knowledge of their functional impact.

A pan-cancer analysis of the expression and prognostic significance of PDRG1

Background

PDRG1 are involved in various physiological regulations of cells, include cell proliferation, growth, apoptosis and cell cycle regulation, but their roles in cancer have not been clearly studied.

Methods

Firstly, we evaluated the expression and prognostic significance of PDRG1 using a pan-cancer analysis of The Cancer Genome Atlas (TCGA) and Genotypic Tissue Expression (GTEx) databases. Secondly, correlations between PDRG1 and pan-cancer immune cells, m6A methylation, tumor mutation burden (TMB), and microsatellite instability (MSI) were investigated. Finally, we explored the relationship between PDRG1 expression and clinical stage in hepatocellular carcinoma (HCC).

Results

We found that PDRG1 was significantly overexpressed in bladder urothelial carcinoma (BLCA), breast invasive carcinoma (BRCA), cholangiocarcinoma (CHOL), liver hepatocellular carcinoma (LIHC), and other tumor tissues and was associated with prognosis. In addition, PDRG1 was closely associated with pan-cancer immune cells, m6A methylation, TMB, and MSI expression. The expression of PDRG1 in HCC was correlated with clinical stage, and western blot assay confirmed that PDRG1 was significantly overexpressed in HCC tissues.

Conclusions

PDRG1 may be an important pan-cancer molecular biomarker for diagnosis and prognosis, and our results may provide a theoretical basis for its future clinical application in cancer diagnosis, treatment, and prognosis, and have been preliminarily validated in HCC.

A comprehensive analysis of prefoldins and their implication in cancer

Prefoldins (PFDNs) are evolutionary conserved co-chaperones, initially discovered in archaea but universally present in eukaryotes. PFDNs are prevalently organized into hetero-hexameric complexes. Although they have been overlooked since their discovery and their functions remain elusive, several reports indicate they act as co-chaperones escorting misfolded or non-native proteins to group II chaperonins. Unlike the eukaryotic PFDNs which interact with cytoskeletal components, the archaeal PFDNs can bind and stabilize a wide range of substrates, possibly due to their great structural diversity. The discovery of the unconventional RPB5 interactor (URI) PFDN-like complex (UPC) suggests that PFDNs have versatile functions and are required for different cellular processes, including an important role in cancer. Here, we summarize their functions across different species. Moreover, a comprehensive analysis of PFDNs genomic alterations across cancer types by using large-scale cancer genomic data indicates that PFDNs are a new class of non-mutated proteins significantly overexpressed in some cancer types.

PDRG1 predicts a poor prognosis and facilitates the proliferation and metastasis of colorectal cancer

OBJECTIVE

The incidence and mortality of colorectal cancer (CRC) is increasing yearly and CRC patients are becoming younger in global. Evidences have revealed the carcinogenic effect of p53 and DNA damage-regulated gene 1 (PDRG1) in several types of tumors. However, its biological function is yet to be investigated in CRC. This study aimed to unveil the prooncogenic role of PDRG1 in CRC.

METHODS

We detected the expression and clinical pathological features of PDRG1 in CRC tissues and paired non-tumor adjacent tissues. The biological role and molecular mechanism of PDRG1 in CRC were characterized through a range of in vitro and in vivo experiments and datasets analysis.

RESULT

We identified the significant up-regulated expression of PDRG1 both in CRC tissues and cell, and higher expression of PDRG1 was associated with worse clinicopathological stage and poorer survival outcome. Cox regression analysis revealed that PDRG1 is an independent prognostic factor for CRC patients. Silencing of PDRG1 significantly retarded CRC cell vitality, invasion and migration, induced cell apoptosis and G0/G1 phase arrest. PDRG1 knockdown also attenuated tumor growth and metastasis as evidencing in vivo experiment. The expression of p21 and apoptosis related protein was enhanced with the knockdown of PDRG1 while cell cycle protein was inhibited.

CONCLUSION

PDRG1 function as a novel oncogene and participate in malignant progression of CRC by regulating p21-mediated signal pathway, suggesting that it can serve as a valuable predictive biomarker for diagnosing of CRC patient and a promising target for therapy.

Functional Contributions of Prefoldin to Gene Expression

Prefoldin is a co-chaperone that evolutionarily originates in archaea, is universally present in all eukaryotes and acts as a co-chaperone by facilitating the supply of unfolded or partially folded substrates to class II chaperonins. Eukaryotic prefoldin is known mainly for its functional relevance in the cytoplasmic folding of actin and tubulin monomers during cytoskeleton assembly. However, the role of prefoldin in chaperonin-mediated folding is not restricted to cytoskeleton components, but extends to both the assembly of other cytoplasmic complexes and the maintenance of functional proteins by avoiding protein aggregation and facilitating proteolytic degradation. Evolution has favoured the diversification of prefoldin subunits, and has allowed the so-called prefoldin-like complex, with specialised functions, to appear. Subunits of both canonical and prefoldin-like complexes have also been found in the nucleus of yeast and metazoan cells, where they have been functionally connected with different gene expression steps. Plant prefoldin has also been detected in the nucleus and is physically associated with a gene regulator. Here we summarise information available on the functional involvement of prefoldin in gene expression, and discuss the implications of these results for the relationship between prefoldin structure and function.

Role of the PAQosome in Regulating Arrangement of Protein Quaternary Structure in Health and Disease

The PAQosome, formerly known as the R2TP/PFDL complex, is an eleven-subunit cochaperone complex that assists HSP90 in the assembly of numerous large multisubunit protein complexes involved in essential cellular functions such as protein synthesis, ribosome biogenesis, transcription, splicing, and others. In this review, we discuss possible mechanisms of action and role of phosphorylation in the assembly of client complexes by the PAQosome as well as its potential role in cancer, ciliogenesis and ciliopathies.