FKBP38 Protects Bcl-2 from Caspase-dependent Degradation

The cellular processes that regulate Bcl-2 at the posttranslational levels are as important as those that regulate bcl-2 synthesis. Previously we demonstrated that the suppression of FK506-binding protein 38 (FKBP38) contributes to the instability of Bcl-2 or leaves Bcl-2 unprotected from degradation in an unknown mechanism. Here, we studied the underlying molecular mechanism mediating this process. We first showed that Bcl-2 binding-defective mutants of FKBP38 fail to accumulate Bcl-2 protein. We demonstrated that the FKBP38-mediated Bcl-2 stability is specific as the levels of other anti-apoptotic proteins such as Bcl-X^L and Mcl-1 remained unaffected. FKBP38 enhanced the Bcl-2 stability under the blockade of de novo protein synthesis, indicating it is posttranslational. We showed that the overexpression of FKBP38 attenuates reduction rate of Bcl-2, thus resulting in an increment of the intracellular Bcl-2 level, contributing to the resistance of apoptotic cell death induced by the treatment of kinetin riboside, an anticancer drug. Caspase inhibitors markedly induced the accumulation of Bcl-2. In caspase-3-activated cells, the knockdown of endogenous FKBP38 by small interfering RNA resulted in Bcl-2 down-regulation as well, which was significantly recovered by the treatment with caspase inhibitors or overexpression of FKBP38. Finally we presented that the Bcl-2 cleavage by caspase-3 is blocked when Bcl-2 binds to FKBP38 through the flexible loop. Taken together, these results suggest that FKBP38 is a key player in regulating the function of Bcl-2 by antagonizing caspase-dependent degradation through the direct interaction with the flexible loop domain of Bcl-2, which contains the caspase cleavage site.     

Systematically assessing the influence of 3-dimensional structural context on the molecular evolution of mammalian proteomes

The 3-dimensional (3D) structural context of amino acid residues in a protein could significantly impact the level of selective constraint on the residues. Here, by analyzing 767 mammalian proteins, we systematically investigate how various 3D structural contexts influence selective constraint. The structural contexts we examined include solvent accessibility, secondary structure, and intramolecular residue-residue interactions. Through this analysis, we offer quantitative information on how 3D structural contexts affect the level of selective constraint.     

SNP identification, linkage disequilibrium, and haplotype analysis for a 200-kb genomic region in a Korean population

Understanding patterns of linkage disequilibrium (LD) across genomes may facilitate association mapping studies to localize genetic variants influencing complex diseases, a recognition that led to the International Haplotype Mapping Project (HapMap). Divergent patterns of haplotype frequency and LD across global populations require that the HapMap database be supplemented with haplotype and LD data from additional populations. We conducted a pilot study of the LD and haplotype structure of a genomic region in a Korean population. A total of 165 SNPs were identified in a 200-kb region of 22q13.2 by direct sequencing. Unphased genotype data were generated for 76 SNPs in 90 unrelated Korean individuals. LD, haplotype diversity, and recombination rates were assessed in this region and compared with the HapMap database. The pattern of LD and haplotype frequencies of Korean samples showed a high degree of similarity with Japanese data. There was a strong correlation between high LD and low recombination frequency in this region. We found considerable similarities in local LD patterns between three Asian populations (Han Chinese, Japanese, and Korean) and the CEPH population. Haplotype frequencies were, however, significantly different between them. Our results should further the understanding of distinctive Korean genomic features and assist in designing appropriate association studies.     

Molecular characterization of the recombinant A-chain of a type II ribosome-inactivating protein (RIP) from Viscum album coloratum and structural basis on its ribosome-inactivating activity and the sugar-binding properties of the B-chain

Mistletoe (Viscum album) lectins, which are classified as a type II ribosome-inactivating protein (RIP) due to their unique biological function and the potential medical and therapeutic application in cancer cells, receive a rising attention. The heterodimeric glycoproteins contain the Achain with catalytic activity and the B-chain with sugar binding properties. In recent years, studies involving the lectins from the white berry European mistletoe (Viscum album) and the yellow berry Korean mistletoe (Viscum album coloratum) have been described. However, the detailed mechanism in exerting unique cytotoxic effect on cancer cells still remains unclear. Here, we aim to understand and define the molecular basis and biological effects of the type II RIPs, through the studies of the recombinant Korean mistletoe lectin. To this end, we expressed, purified the recombinant Korean mistletoe lectin (rKML), and investigated its molecular characteristics in vitro, its cytotoxicity and ability to induce apoptotic cell death in cancer cells. To gain structural basis for its catalytic activity and sugar binding properties, we performed homology modeling studies based on the high degree of sequence identity and conserved secondary structure prediction between Korean and European, Himalayan mistletoe lectins, and Ricin.     

The preparation of D-phenylalanine imprinted microbeads by a novel method of modified suspension polymerization

Molecularly imprinted polymeric microbeads (MIPMs) were prepared by the suspension and modified suspension polymerization methods using D-phenylalanine as the template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, toluene as the porogen, polyvinyl alcohol as the stabilizer, and sodium dodecyl sulfate as the surfactant. The addition of a surfactant to the conventional suspension polymerization mixture decreased the mean particle size of the MIPMs and increased the adsorption selectivity. For the modified suspension polymerization method, the mean particle size of the MIPMs was smaller than the particle size of MIPMs prepared via conventional suspension polymerization. Moreover, the adsorption selectivity improved considerably compared to the adsorption selectivities of MIPs reported previously.     

Determination of functional strength imbalance of the lower extremities

The purposes of this study were (a) to determine whether a significant strength imbalance existed between the left and right or dominant (D) and nondominant (ND) legs and (b) to investigate possible correlations among various unilateral and bilateral closed kinetic chain tests, including a field test, and traditional isokinetic dynamometry used to determine strength imbalance. Fourteen Division I collegiate women softball players (20.2 +/- 1.4 years) volunteered to undergo measures of average peak torque for isokinetic flexion and extension at 60 degrees .s(-1) and 240 degrees .s(-1); in addition, measures of peak and average force of each leg during parallel back squat, 2-legged vertical jump, and single-leg vertical jump and performance in a 5-hop test were examined. Significant differences of between 4.2% and 16.0% were evident for all measures except for average force during single-leg vertical jump between the D and ND limbs, thus revealing a significant strength imbalance. The 5-hop test revealed a significant difference between D and ND limbs and showed a moderate correlation with more sophisticated laboratory tests, suggesting a potential use as a field test for the identification of strength imbalance. The results of this study indicate that a significant strength imbalance can exist even in collegiate level athletes, and future research should be conducted to determine how detrimental these imbalances could be in terms of peak performance for athletes, as well as the implications for injury risk.     

Tunicothrix rostrata n. g., n. sp., a new urostylid ciliate (Ciliophora, Stichotrichia) from the Yellow Sea

The morphology and infraciliature of a new ciliate, Tunicothrix rostrata n. g., n. sp., isolated from the Yellow Sea, are investigated using live observation and protargol impregnation. Tunicothrix rostrata measures about 160 x 40 mum in vivo, and has a frontal beak-like protrusion, a conspicuous cortical alveolar layer, two right marginal rows, and usually three distinct midventral pairs. The discovery of T. rostrata enables us to reconsider the classification of Erniella wilberti, a curious ciliate with obscure midventral pairs. Both species are highly similar in overall appearance and nuclear and ciliary pattern. Thus, they are united in a new genus of the family Urostylidae, Tunicothrix, and E. wilberti is transferred to Tunicothrix: Tunicothrix wilbertiLin and Song, 2004 n. comb. By contrast, Erniella filiformis, type species of Erniella, has several ventral rows and does not belong to the urostylids. Tunicothrix rostrata is easily distinguished from T. wilberti by its beak-like anterior protrusion and by the distinctly elongated right marginal row 2, which curves anteriorly on the dorsal side of the cells. Tunicothrix is closely related to Parabirojimia, differing by the invariably two (vs. five-eight) right marginal rows and the conspicuous (vs. ordinary) alveolar layer, a unique feature in urostylid ciliates.