Stem-cell-abundant proteins Nanog, Nucleostemin and Musashi1 are highly expressed in malignant cervical epithelial cells

<p>Abstract</p> <p>Background</p> <p>Nanog, nucleostemin (NS) and musashi1 (Msi1) are proteins that are highly expressed in undifferentiated embryonic stem (ES) cells and have been shown to be essential in maintaining the pluripotency and regulating the proliferation and asymmetric division of ES cells and several nervous system tumor cells. The roles of Nanog, NS and Msi1 in development and progression of cervical carcinoma have, until now, not been well documented.</p> <p>Methods</p> <p>In this study, expression of Nanog, NS and Msi1 was detected by immunohistochemistry analysis in 235 patients with various degrees of cervical epithelial lesions, including 49 with normal cervical epithelia, 31 with mild dysplasia (CIN I), 77 with moderate-severe dysplasia (CIN II-III) and 78 with squamous cervical carcinomas (SCCs). Associations with various clinical pathological prognostic variables were analyzed in 50 early-stage SCC patients.</p> <p>Results</p> <p>Nanog, NS and Msi1 expression levels were significantly higher in SCC patients compared with CIN patients, and were higher in CIN patients compared with those with normal cervical epithelia. Nanog expression levels showed significantly differences according to different tumor sizes (P < 0.05), whereas there were no differences in NS and Msi1 expression levels according to different clinical pathological parameters.</p> <p>Conclusion</p> <p>Our findings indicate that Nanog, NS and Msi1 may be involved in carcinogenesis of the cervix and progression of cervical carcinoma.</p

Methyl group assignment using pseudocontact shifts with PARAssign

Macromolecular Biochemistr

Conformational features and ionization states of Lys side chains in a protein studied using the stereo-array isotope labeling (SAIL) method

Although both the hydrophobic aliphatic chain and hydrophilic ζ-amino group of the Lys side chain presumably contribute to the structures and functions of proteins, the dual nature of the Lys residue has not been fully investigated using NMR spectroscopy, due to the lack of appropriate methods to acquire comprehensive information on its long consecutive methylene chain. We describe herein a robust strategy to address the current situation, using various isotope-aided NMR technologies. The feasibility of our approach is demonstrated for the Δ+PHS/V66K variant of staphylococcal nuclease (SNase), which contains 21 Lys residues, including the engineered Lys-66 with an unusually low pKa of ∼ 5.6. All of the NMR signals for the 21 Lys residues were sequentially and stereospecifically assigned using the stereo-array isotope-labeled Lys (SAIL-Lys), [U-13C,15N; β2,γ2,δ2,ε3-D4]-Lys. The complete set of assigned 1H, 13C, and 15N NMR signals for the Lys side-chain moieties affords useful structural information. For example, the set includes the characteristic chemical shifts for the 13Cδ, 13Cε, and 15Nζ signals for Lys-66, which has the deprotonated ζ-amino group, and the large upfield shifts for the 1H and 13C signals for the Lys-9, Lys-28, Lys-84, Lys-110, and Lys-133 side chains, which are indicative of nearby aromatic rings. The 13Cε and 15Nζ chemical shifts of the SNase variant selectively labeled with either [ε-13C;ε,ε-D2]-Lys or SAIL-Lys, dissolved in H2O and D2O, showed that the deuterium-induced shifts for Lys-66 were substantially different from those of the other 20 Lys residues. Namely, the deuterium-induced shifts of the 13Cε and 15Nζ signals depend on the ionization states of the ζ-amino group, i.e., −0.32 ppm for Δδ13Cε [NζD3+-NζH3+] vs. −0.21 ppm for Δδ13Cε [NζD2-NζH2] and −1.1 ppm for Δδ15Nζ[NζD3+-NζH3+] vs. −1.8 ppm for Δδ15Nζ[NζD2-NζH2]. Since the 1D 13C NMR spectrum of a protein selectively labeled with [ε-13C;ε,ε-D2]-Lys shows narrow (&gt; 2 Hz) and well-dispersed 13C signals, the deuterium-induced shift difference of 0.11 ppm for the protonated and deprotonated ζ-amino groups, which corresponds to 16.5 Hz at a field strength of 14 T (150 MHz for 13C), could be accurately measured. Although the isotope shift difference itself may not be absolutely decisive to distinguish the ionization state of the ζ-amino group, the 13Cδ, 13Cε, and 15Nζ signals for a Lys residue with a deprotonated ζ-amino group are likely to exhibit distinctive chemical shifts as compared to the normal residues with protonated ζ-amino groups. Therefore, the isotope shifts would provide a useful auxiliary index for identifying Lys residues with deprotonated ζ-amino groups at physiological pH levels.</p

Methyl-Specific Isotope Labeling Strategies for NMR Studies of Membrane Proteins

International audienceMethyl groups are very useful probes of structure, dynamics and interactions in protein NMR spectroscopy. In particular, methyl-directed experiments provide high sensitivity even in very large proteins, such as membrane proteins in a membrane-mimicking environment. In this chapter we discuss the approach for labelling methyl groups in E. coli based protein expression, as exemplified with the mitochondrial carrier GGC