Four New Species of Xenylla (Collembola: Hypogastruridae) from Korea

ABSTRACT Four new species of the collembolan genus Xenylla, X. convexopyga, X. longistriata, X. dotata and X. marina from Korea are described. X. convexopyga is characterized by an absence of the dorsal seta m₃ on Th. II-III. While the other three new species share similarities in dorsal chaetotaxic characters. However, they are dissimilar in the following respects: ventral chaetotaxy, body colour, presence or absence of inner teeth on unguis, the length proportion of abdominal segments and thoracic segments, arrangement of anal papillae and the general shape of apical bulb of fourth antennal segment. As a result of this study, a total of 25 species in 6 genera of Hypogastruridae have been recorded from the Korean Peninsula.     

The global translation profile in a ribosomal protein mutant resembles that of an eIF3 mutant

Background

Genome-wide assays performed in Arabidopsis and other organisms have revealed that the translation status of mRNAs responds dramatically to different environmental stresses and genetic lesions in the translation apparatus. To identify additional features of the global landscape of translational control, we used microarray analysis of polysomal as well as non-polysomal mRNAs to examine the defects in translation in a poly(A) binding protein mutant, pab2 pab8, as well as in a mutant of a large ribosomal subunit protein, rpl24b/shortvalve1.

Results

The mutation of RPL24B stimulated the ribosome occupancy of mRNAs for nuclear encoded ribosomal proteins. Detailed analysis yielded new insights into the translational regulon containing the ribosomal protein mRNAs. First, the ribosome occupancy defects in the rpl24b mutant partially overlapped with those in a previously analyzed initiation factor mutant, eif3h. Second, a group of mRNAs with incomplete coding sequences appeared to be uncoupled from the regulon, since their dependence on RPL24B differed from regular mRNAs. Third, different sister paralogs of the ribosomal proteins differed in their translation state in the wild-type. Some sister paralogs also differed in their response to the rpl24b mutation. In contrast to rpl24b, the pab2 pab8 mutant revealed few gene specific translational defects, but a group of seed storage protein mRNAs were stimulated in their ribosome occupancy. In the course of this work, while optimizing the statistical analysis of ribosome occupancy data, we collected 12 biological replicates of translation states from wild-type seedlings. We defined 20% of mRNAs as having a high variance in their translation state. Many of these mRNAs were functionally associated with responses to the environment, suggesting that subtle variation in the environmental conditions is sensed by plants and transduced to affect the translational efficiency of hundreds of mRNAs.

Conclusions

These data represent the first genome-wide analysis of translation in a eukaryote defective in the large ribosomal subunit. RPL24 and eIF3h play similar but non-identical roles in eukaryotic translation. The data also shed light on the fine structure of the regulon of ribosomal protein mRNAs.

     

Regulation of WNK1 by an autoinhibitory domain and autophosphorylation

WNK family protein kinases are large enzymes that contain the catalytic lysine in a unique position compared with all other protein kinases. These enzymes have been linked to a genetically defined form of hypertension. In this study we introduced mutations to test hypotheses about the position of the catalytic lysine, and we examined mechanisms involved in the regulation of WNK1 activity. Through the analysis of enzyme fragments and sequence alignments, we have identified an autoinhibitory domain of WNK1. This isolated domain, conserved in all four WNKs, suppressed the activity of the WNK1 kinase domain. Mutation of two key residues in this autoinhibitory domain attenuated its ability to inhibit WNK kinase activity. Consistent with these results, the same mutations in a WNK1 fragment that contain the autoinhibitory domain increased its kinase activity. We also found that WNK1 expressed in bacteria is autophosphorylated; autophosphorylation on serine 382 in the activation loop is required for its activity.     

Polymorphisms of the prion protein gene (PRNP) in Hanwoo (Bos taurus coreanae) and Holstein cattle

Polymorphisms in the prion protein gene (PRNP) in humans and sheep correlate with susceptibility to transmissible spongiform encephalopathies (TSEs). Bovine spongiform encephalopathy (BSE) has been reported in British and Japanese cattle; it has occurred thus far in Holstein cattle. BSE in Hanwoo (Bos taurus coreanae) cattle has not been diagnosed up to now. To characterize the bovine PRNP polymorphisms in Korean cattle, we analyzed the open reading frame (ORF) of PRNP in 120 Hanwoo (beef) cattle and 53 Holstein (dairy) cattle. Three polymorphisms were found, the third position of codon 78 (G-->A), the third position of codon 192 (C-->T), and the deletion of a single octa-repeat. An analysis of codon 78 revealed no difference in the genotype (P = 0.2026) or allele (P = 0.7180) frequencies between Hanwoo and Holstein animals. However, there were significant differences in the genotype (P < 0.0001) and allele (P < 0.0001) frequencies at PRNP codon 192 between Hanwoo and Holstein animals. The rate of Holstein animals with deletion of a single octa-repeat was 91.5% undeleted homozygotes, 8.5% heterozygotes (with R3 deletion), and 0% deleted homozygotes. However, none of the 120 Hanwoo animals had any octa-repeat deletions. The genotype (P < 0.0001) and allele (P < 0.0001) frequencies of a single octa-repeat-deletion were also significantly different between Hanwoo and Holstein animals.     

Properties of WNK1 and implications for other family members

WNKs are large serine/threonine protein kinases structurally distinct from all other members of the protein kinase superfamily. Of the four human WNK family members, WNK1 and WNK4 have been linked to a hereditary form of hypertension, pseudohypoaldosteronism type II. We characterized the biochemical properties and regulation of WNK1 that may contribute to its physiological activities and abnormal function in disease. We showed that WNK1 is activated by hypertonic stress in kidney epithelial cells and in breast and colon cancer cell lines. In addition, hypotonic stress also led to a modest increase in WNK1 activity. Gel filtration suggested that WNK1 exists as a tetramer, and yeast two-hybrid data showed that the N terminus of WNK1 (residues 1-222) interacts with residues 481-660, which includes the WNK1 autoinhibitory domain and a C-terminal coiled-coil domain. Although cell biological studies have suggested a functional interaction between WNK1 and WNK4, we found no evidence of stable interactions between these kinases. However, WNK1 phosphorylated both WNK4 and WNK2. In addition, the WNK1 autoinhibitory domain inhibited the catalytic activity of these WNKs. These findings suggest potential mechanisms for interconnected regulation of WNK family members.     

WNK1 activates ERK5 by an MEKK2/3-dependent mechanism

WNK1 belongs to a unique protein kinase family that lacks the catalytic lysine in its normal position. Mutations in human WNK1 and WNK4 have been implicated in causing a familial form of hypertension. Here we report that overexpression of WNK1 led to increased activity of cotransfected ERK5 in HEK293 cells. ERK5 activation was blocked by the MEK5 inhibitor U0126 and expression of a dominant negative MEK5 mutant. Expression of dominant negative mutants of MEKK2 and MEKK3 also blocked activation of ERK5 by WNK1. Moreover, both MEKK2 and MEKK3 coimmunoprecipitated with endogenous WNK1 from cell lysates. WNK1 phosphorylated both MEKK2 and -3 in vitro, and MEKK3 was activated by WNK1 in 293 cells. Finally, ERK5 activation by epidermal growth factor was attenuated by suppression of WNK1 expression using small interfering RNA. Taken together, these results place WNK1 in the ERK5 MAP kinase pathway upstream of MEKK2/3.     

Synthesis of novel multivalent fluorescent inhibitors with high affinity to prostate cancer and their biological evaluation

Prostate-specific membrane antigen (PSMA) is an important biological target for therapy and diagnosis of prostate cancer. In this study, novel multivalent PSMA inhibitors with glutamate-urea-lysine structures were designed to improve inhibition characteristics. Precursors of the novel inhibitors were prepared from glutamic acid with di-tert-butyl ester. A near-infrared molecular dye, sulfo-Cy5.5, was introduced into the precursors to generate the final PSMA fluorescent inhibitors, compounds 12–14, to visualize prostate cancer. Biological behaviors of the inhibitors were evaluated using in vitro inhibition assays, in vivo fluorescent imaging, and ex vivo biodistribution assays. K_i values from inhibition studies indicated that dimeric inhibitor 13 with a glutamine linker showed approximately 3-fold more inhibitory activity than monomeric inhibitor 12. According to other biological studies using a mouse model of prostate cancer, dimeric inhibitor compounds 13 and 14 had higher tumor accumulation than the monomer. However, glutamine-based dimeric inhibitor 13 showed lower liver uptake than dimeric inhibitor 14, which had a benzene structure. Thus, these studies suggest that glutamine-based dimeric inhibitor 13 can be a promising optical inhibitor of prostate cancer.     

Four New Species of Symphypleona (Collembola) from Korea

ABSTRACT Four new species of Symphypleona, Ptenothrix plumiseta, Deuterosminthurus serratus, Sminthurus annulatus, Smithurinus distinctus , are described from Korea. Especially two genera, Deuterosminthurus and Sminthurinus are new record to Korea. Korean Collembola Symphypleona add up to 18 species, 11 genera in 6 family.