Cancer cells secrete small membranous extracellular vesicles (EVs) into their microenvironment and circulation. Although their potential as cancer biomarkers has been promising, the identification and quantification of EVs in clinical samples remains challenging. Here we describe a sensitive and rapid analytical technique for profiling circulating EVs directly from blood samples of patients with colorectal cancer. EVs are captured by two types of antibodies and are detected by photosensitizer-beads, which enables us to detect cancer-derived EVs without a purification step. We also show that circulating EVs can be used for detection of colorectal cancer using the antigen CD147, which is embedded in cancer-linked EVs. This work describes a new liquid biopsy technique to sensitively detect disease-specific circulating EVs and provides perspectives in translational medicine from the standpoint of diagnosis and therapy.

Several cell types, including tumour cells, secrete extracellular vesicles (EVs), and tumour-derived EVs play a role in cancer initiation and progression. These vesicles include both a common set of membrane and cytosolic proteins and origin-specific subsets of proteins that likely correlated to cell type–associated functions. To confirm the presence of EVs in the preparations, researchers have identified so-called EV marker proteins, including the tetraspanin family proteins and such cytosolic proteins as heat shock 70 kDa protein 4 (HSP70) and tumour susceptibility gene 101 (TSG101). However, studies have shown that some EV markers are not always present in all EVs, which not only complicates the identification of EVs but also precludes the quantitative evaluation of EV proteins. Thus, it is strongly required to explore well-conserved EV marker proteins that are present at similar levels, regardless of their tissue or cellular origin. In this study, we compared the presence of 11 well-known EV marker proteins by immunoblotting using EVs isolated from 4 human prostate cell lines and 5 human breast cell lines, including cancer cells with different phenotypes. We found that all the tested EVs were positive for CD9 and CD81, with similar abundance that was irrespective of the EV origin. In contrast, other EV marker proteins, such as TSG101, Rab-5b and CD63, were detected in an inconsistent manner, depending on the origin of the EVs. Thus, we propose that the detection of CD9 and/or CD81 should ensure the presence of EVs.

Heterogeneous nuclear ribonucleoprotein D, also known as AUF1, has two DNA/RNA-binding domains, each of which can specifically bind to single-stranded d(TTAGGG) n , the human telomeric repeat. Here, the structure of the C-terminal-binding domain (BD2) complexed with single-stranded d(TTAGGG) determined by NMR is presented. The structure has revealed that each residue of the d(TAG) segment is recognized by BD2 in a base-specific manner. The interactions deduced from the structure have been confirmed by gel retardation experiments with mutant BD2 and DNA. It is known that single-stranded DNA with the telomeric repeat tends to form a quadruplex and that the quadruplex has an inhibitory effect on telomere elongation by telomerase. This time it is revealed that BD2 unfolds the quadruplex of such DNA upon binding. Moreover, the effect of BD2 on the elongation by telomerase was examined in vitro. These results suggest the possible involvement of heterogeneous nuclear ribonucleoprotein D in maintenance of the telomere 3-overhang either through protection of a single-stranded DNA or destabilization of the potentially deleterious quadruplex structure for the elongation by telomerase. Heterogeneous nuclear ribonucleoprotein (hnRNP)1 D, also known as AUF1, was isolated from a HeLa cell nuclear extract as a protein that binds specifically to single-stranded d(T-TAGGG) n , the human telomeric DNA repeat (1). It also binds to r(UUAGGG) n (1) and the AU-rich element of the 3Ј-untranslated region of mRNA (2). It was shown biochemically that hnRNP D binding to the Gua-rich telomeric strand d(T-TAGGG) n destabilizes intrastrand Gua:Gua pairing and that hnRNP D interacts specifically with telomerase in human cell extracts (3). Thus, the involvement of hnRNP D in the maintenance of telomere DNA has been implied.hnRNP D consists of 306 amino acid residues and comprises two ribonucleoprotein (RNP)-type DNA/RNA-binding domains (BDs), BD1 (70 -173) and BD2 (174 -256), and a region rich in glycine and arginine residues (257-306) (4). The RNP-type BD is one of the most common eukaryotic protein sequence motifs for DNA/RNA binding (5), being found in hundreds of proteins (6 -9). A single BD of hnRNP D, either BD1 or BD2, is able to bind to DNA and RNA in a sequence-specific manner (4, 10, 11). The binding affinity of either BD1 or BD2 is comparable with that of the protein having both BD1 and BD2 (4). These results suggest that the basis of the interactions of hnRNP D with DNA and RNA can be addressed by examination with a single BD. We have already reported the structures of BD1 (10) and BD2 (11). We also qualitatively identified the surfaces of BD1 (10) and BD2 (11) interactive with DNA and RNA on chemical shift perturbation analysis, although it should be kept in mind that the perturbation is caused not only through the direct interaction but also thorough the indirect effect of the interaction. Essentially the same surfaces of the BDs are used for the interactions with DNA and RNA.Here, we present the structure of BD2 complexed with d(...

Serum BDNF levels are positively related to the impairment of verbal memory and attention, plasma HVA levels are positively related to motor function, and plasma MHPG levels are positively related to attention in patients with schizophrenia.

In plant cells, boron (B) occurs predominantly as a borate ester associated with rhamnogalacturonan II (RG-II), but the function of this B-RG-II complex has yet to be investigated. 3-Deoxy-D-manno-2-octulosonic acid (KDO) is a specific component monosaccharide of RG-II. Mutant plants defective in KDO biosynthesis are expected to have altered RG-II structure, and would be useful for studying the physiological function of the B-RG-II complex. Here, we characterized Arabidopsis CTP:KDO cytidylyltransferase (CMP-KDO synthetase; CKS), the enzyme activating KDO as a nucleotide sugar prior to its incorporation into RG-II. Our analyses localized the Arabidopsis CKS protein to mitochondria. The Arabidopsis CKS gene occurs as a single-copy gene in the genome, and we could not obtain cks null mutants from T-DNA insertion lines. Analysis using +/cks heterozygotes in the quartet1 background demonstrated that the cks mutation rendered pollen infertile through the inhibition of pollen tube elongation. These results suggest that KDO is an indispensable component of RG-II, and that the complete B-RG-II complex is essential for the cell wall integrity of rapidly growing tissues.