The molecular chaperone TRiC/CCT binds to the Trp-Asp 40 (WD40) repeat protein WDR68 and promotes its folding, protein kinase DYRK1A binding, and nuclear accumulation.

Trp-Asp (WD) repeat protein 68 (WDR68) is an evolutionarily conserved WD40 repeat protein that binds to several proteins, including dual specificity tyrosine phosphorylation-regulated protein kinase (DYRK1A), MAPK/ERK kinase kinase 1 (MEKK1), and Cullin4-damage-specific DNA-binding protein 1 (CUL4-DDB1). WDR68 affects multiple and diverse physiological functions, such as controlling anthocyanin synthesis in plants, tissue growth in insects, and craniofacial development in vertebrates. However, the biochemical basis and the regulatory mechanism of WDR68 activity remain largely unknown. To better understand the cellular function of WDR68, here we have isolated and identified cellular WDR68 binding partners using a phosphoproteomic approach. More than 200 cellular proteins with wide varieties of biochemical functions were identified as WDR68-binding protein candidates. Eight T-complex protein 1 (TCP1) subunits comprising the molecular chaperone TCP1 ring complex/chaperonin-containing TCP1 (TRiC/CCT) were identified as major WDR68-binding proteins, and phosphorylation sites in both WDR68 and TRiC/CCT were identified. Co-immunoprecipitation experiments confirmed the binding between TRiC/CCT and WDR68. Computer-aided structural analysis suggested that WDR68 forms a seven-bladed ß-propeller ring. Experiments with a series of deletion mutants in combination with the structural modeling showed that three of the seven ß-propeller blades of WDR68 are essential and sufficient for TRiC/CCT binding. Knockdown of cellular TRiC/CCT by siRNA caused an abnormal WDR68 structure and led to reduction of its DYRK1A-binding activity. Concomitantly, nuclear accumulation of WDR68 was suppressed by the knockdown of TRiC/CCT, and WDR68 formed cellular aggregates when overexpressed in the TRiC/CCT-deficient cells. Altogether, our results demonstrate that the molecular chaperone TRiC/CCT is essential for correct protein folding, DYRK1A binding, and nuclear accumulation of WDR68.

Significant increase of plasma tetranectin in ovx mice as defined by proteomics analysis.

BACKGROUND: Proteomics is recognized as a useful tool in the dynamic screening of plasma protein expression. This study aimed to identify increased expressions of novel plasma proteins in ovariectomized mice (ovx) using selective reaction monitoring (SRM) validation in combination with electrospray ionized-quadrupole time-of-flight mass spectrometry (ESI-Q-TOF-MS) screening. MATERIALS AND METHODS: Twenty-week-old female C57BL/6 mice were ovariectomized or subjected to surgical exposure of the ovaries alone (sham). Blood plasma protein at 4 weeks after these operations was pooled for the ovx and sham group each and separated on SDS-PAGE, and then digested by peptides, which were first differentially displayed by ESI-Q-TOF-MS analysis. Mass spectra of peptides upregulated more than twofold in ovx compared to sham mice were selected for protein identification by ESI-Q-TOF-MS. The selected peptides were further validated in independent samples by SRM using electrospray ionized-triple quadrupole-linear ion trap mass spectrometry (ESI-QqLIT-MS). Optimum transitions for SRM were manually chosen for their high specificity in identifying peptides derived from the candidate proteins. RESULTS: Differential analysis of peptides revealed 1,108 upregulated peptides in ovx compared with sham control mice. Among the upregulated peptides, 231 nonredundant proteins were identified. Validation analysis for the potential use of these proteins as markers of bone turnover was performed using ESI-QqLIT-MS. The four proteins from the plasma samples, namely mannose-binding lectin-C, major urinary protein 2, type I collagen alpha 2 chain, and tetranectin, were evaluated in a blinded manner. A statistically significant elevation of all four proteins in the plasma of ovx mice was confirmed by SRM. Of the four upregulated plasma proteins, tetranectin increased by almost 50 times in the ovx mice compared with the sham mice. CONCLUSIONS: On the basis of proteomics analysis, this study demonstrated that four plasma proteins were significantly elevated in the ovx mice; of these, tetranectin was markedly upregulated by almost 50 times compared with the sham mice.

Sialic acid-focused quantitative mouse serum glycoproteomics by multiple reaction monitoring assay.

Despite increasing importance of protein glycosylation, most of the large-scale glycoproteomics have been limited to profiling the sites of N-glycosylation. However, in-depth knowledge of protein glycosylation to uncover functions and their clinical applications requires quantitative glycoproteomics eliciting both peptide and glycan sequences concurrently. Here we describe a novel strategy for the multiplexed quantitative mouse serum glycoproteomics based on a specific chemical ligation, namely, reverse glycoblotting technique, focusing sialic acids and multiple reaction monitoring (MRM). LC-MS/MS analysis of de-glycosylated peptides identified 270 mouse serum peptides (95 glycoproteins) as sialylated glycopeptides, of which 67 glycopeptides were fully characterized by MS/MS analyses in a straightforward manner. We revealed the importance of a fragment ion containing innermost N-acetylglucosamine (GlcNAc) residue as MRM transitions regardless the sequence of the peptides. Versatility of the reverse glycoblotting-assisted MRM assays was demonstrated by quantitative comparison of 25 targeted glycopeptides from 16 proteins between mice with homo and hetero types of diabetes disease model.

Fecal microbiota in patients with a stoma decreases anaerobic bacteria and alters taxonomic and functional diversities.

Colorectal cancer (CRC) is one of the most common malignant diseases. Generally, stoma construction is performed following surgery for the resection of the primary tumor in patients with CRC. The association of CRC with the gut microbiota has been widely reported, and the gut microbiota is known to play an important role in the carcinogenesis, progression, and treatment of CRC. In this study, we compared the microbiota of patients with CRC between with and without a stoma using fecal metagenomic sequencing data from SCRUM-Japan MONSTAR-SCREEN, a joint industry-academia cancer research project in Japan. We found that the composition of anaerobes was reduced in patients with a stoma. In particular, the abundance of Alistipes, Akkermansia, Intestinimonas, and methane-producing archaea decreased. We also compared gene function (e.g., KEGG Orthology and KEGG pathway) and found that gene function for methane and short-chain fatty acids (SCFAs) production was underrepresented in patients with a stoma. Furthermore, a stoma decreased Shannon diversity based on taxonomic composition but increased that of the KEGG pathway. These results suggest that the feces of patients with a stoma have a reduced abundance of favorable microbes for cancer immunotherapy. In conclusion, we showed that a stoma alters the taxonomic and functional profiles in feces and may be a confounding factor in fecal microbiota analysis.

Vanadium-binding proteins (vanabins) from a vanadium-rich ascidian Ascidia sydneiensis samea.

Since the beginning of the last century, it has been known that ascidians accumulate high levels of a transition metal, vanadium, in their blood cells, although the mechanism for this curious biological function remains unknown. Recently, we identified three vanadium-binding proteins (vanabins), previously denoted as vanadium-associated proteins (VAPs) [Zool. Sci. 14 (1997) 37], from the cytoplasm fraction of vanadium-containing blood cells (vanadocytes) of the vanadium-rich ascidian Ascidia sydneiensis samea. Here, we describe the cloning, expression, and analysis of the metal-binding ability of vanabins. Recombinant proteins of two independent but related vanabins, vanabin1 and vanabin2, bound to 10 and 20 vanadium(IV) ions with dissociation constants of 2.1x10(-5) and 2.3x10(-5) M, respectively. The binding of vanadium(IV) to these vanabins was inhibited by the addition of copper(II) ions, but not by magnesium(II) or molybdate(VI) ions. Vanabins are the first proteins reported to show specific binding to vanadium ions; this should provide a clue to resolving the problem regarding the selective accumulation of vanadium in ascidians.

High-throughput synthesis of stable isotope-labeled transmembrane proteins for targeted transmembrane proteomics using a wheat germ cell-free protein synthesis system.

Using a wheat germ cell-free protein synthesis system, we developed a high-throughput method for the synthesis of stable isotope-labeled full-length transmembrane proteins as proteoliposomes to mimic the in vivo environment, and we successfully constructed an internal standard library for targeted transmembrane proteomics by using mass spectrometry.