In vitro SAR of (5-(2H)-isoxazolonyl) ureas, potent inhibitors of hormone-sensitive lipase

A series of (5-(2H)-isoxazolonyl) ureas were developed as nanomolar inhibitors of hormone-sensitive lipase, an enzyme of potential importance in the treatment of diabetes.     

Synthesis and SAR of 2-arylbenzoxazoles, benzothiazoles and benzimidazoles as inhibitors of lysophosphatidic acid acyltransferase-beta

2-Arylbenzoxazoles, benzothiazoles and benzimidazoles were identified as new classes of potent, isoform specific inhibitors of lysophosphatidic acid acyltransferase-beta (LPAAT-beta). Effects of selected inhibitors on proliferation of tumor cells in vitro were investigated.     

Functional genomic approaches using the nematode Caenorhabditis elegans as a model system

Since the completion of the genome project of the nematode C. elegans in 1998, functional genomic approaches have been applied to elucidate the gene and protein networks in this model organism. The recent completion of the whole genome of C. briggsae, a close sister species of C. elegans, now makes it possible to employ the comparative genomic approaches for identifying regulatory mechanisms that are conserved in these species and to make more precise annotation of the predicted genes. RNA interference (RNAi) screenings in C. elegans have been performed to screen the whole genome for the genes whose mutations give rise to specific phenotypes of interest. RNAi screens can also be used to identify genes that act genetically together with a gene of interest. Microarray experiments have been very useful in identifying genes that exhibit co-regulated expression profiles in given genetic or environmental conditions. Proteomic approaches also can be applied to the nematode, just as in other species whose genomes are known. With all these functional genomic tools, genetics will still remain an important tool for gene function studies in the post genome era. New breakthroughs in C. elegans biology, such as establishing a feasible gene knockout method, immortalized cell lines, or identifying viruses that can be used as vectors for introducing exogenous gene constructs into the worms, will augment the usage of this small organism for genome-wide biology.     

Nonconcerted evolution of histone 3 genes in a liverwort, Conocephalum conicum

To estimate the extent of genetic variation at the DNA level, the histone 3 (H3) genes were sequenced from single individual each from the three cryptic species recognized based on allozyme analyses, YFS, J and T types of Conocephalum conicum and two closely related species, C. japonicum and Marchantia polymorpha. Although the H3 genes are known to be highly conserved, the nucleotide diversities were 0.128, 0.109, 0.108, 0.049 and 0.034. These values are 30 to 100 times higher than that in Drosophila melanogaster (0.001). Besides, there were considerable differences in the position, length and number of introns among the loci of H3 genes. The observed high level of nucleotide diversities was explained by the fixation of many random mutations, and non-concerted evolution that resulted from low rates of unequal crossing-over and gene conversion probably due to the dispersed structure of H3 genes on genome in this species. The non-concerted evolutionary pattern was established by the analysis of phylogenetic tree and divergence rates. This study confirmed previous results suggesting that natural populations of liverwort maintains high extent of variation at DNA level.     

Insulin-like growth factor-1 receptor signaling in 3T3-L1 adipocyte differentiation requires lipid rafts but not caveolae

Previously, we have found that lipid rafts/caveolae were essential for insulin-like growth factor-1 (IGF-1) receptor signaling during 3T3-L1 preadipocytes differentiation induction. However, it was not identified as to which of the membrane lipid-ordered microdomains mediates the receptor signal. Using small double-stranded RNA-mediated interference (RNAi), we successfully suppressed the caveolin-1 protein expression. In cells stably transfected with vector expressing small interfering RNA (siRNA) fragment, no caveolin-1 protein or caveola was detected. On the other hand, removal of caveolin-1 did not affect the caveolinless lipid rafts or the localization of IGF-1 receptor in lipid rafts on plasma membrane. IGF-1 receptor signal transduction and induced cellular differentiation were normal in RNAi cells with only lipid rafts. Furthermore, these IGF-1 receptor signaling events were still sensitive to the cholesterol-binding reagents. Thus, our results suggest that lipid rafts are sufficient for IGF-1 receptor signaling and the recruitment of signal molecules by caveolin-1 is not essential for IGF-1 receptor signaling.     

PAK is essential for RAS-induced upregulation of cyclin D1 during the G1 to S transition

Oncogenic RAS mutants such as v-Ha-RAS induce cell cycling, in particular the G1 to S transition, by upregulating cyclin D1 and downregulating p27, an inhibitor for cyclin-dependent kinases (CDKs). PI-3 kinase appears to be involved in the regulation of both cyclin D1 and p27. In this report, using two distinct inhibitors specific for PAK1-3 (CEP-1347 and WR-PAK18), we present the first evidence indicating that the PIX/Rac/CDC42-dependent Ser/Thr kinases PAK1-3, acting downstream of PI-3 kinase and upstream of the Raf/MEK/ERKs kinase cascade, is essential for RAS-induced upregulation of cyclin D1, but not downregulation of p27. Since these PAK-inhibitors block selectively the malignant growth of RAS transformants, in which PAK1 is constitutively activated, but not normal cell growth, it is suggested that RAS transformants are addicted to the high levels of PAK1 for their malignant entry to S phase.     

A novel proteomic coculture model of prostate cancer cell growth

Chemotherapy and androgen ablation therapy are only temporarily effective against prostate cancer, and current studies are ongoing to test agents that target proteins responsible for autocrine and paracrine stimulated growth. Given limitations of current laboratory models to test the effect of these agents on cell growth and protein targets, we developed a coculture model that can distinguish paracrine stimulated growth and effects on proteins. We found that LNCaP prostate cancer cells and an immortalized rat prostate cell line transfected to overexpress the antiapoptotic resistance protein Bcl-2 were stimulated to grow (>2-fold increase, p < 0.01) through autocrine effects from additional cells in an upper chamber of our system. Using a proteomic approach with a two-dimensional differential in gel electrophoresis method to increase fidelity, four proteins were found to increase after autocrine induced growth stimulation. These proteins were all identified by mass spectrometry as enzymes in the glycolytic pathway, validating the ability of this system to detect both clonogenic growth and the effect on proteins. These data, therefore, demonstrate a novel coculture model for further study of agents that target proteins in pathways of paracrine or autocrine stimulated cell growth.     

Estrogen receptor-alpha gene haplotype is associated with primary knee osteoarthritis in Korean population

Estrogen and estrogen receptors (ERs) are known to play important roles in the pathophysiology of osteoarthritis (OA). To investigate ER-alpha gene polymorphisms for its associations with primary knee OA, we conducted a case-control association study in patients with primary knee OA (n = 151) and healthy individuals (n = 397) in the Korean population. Haplotyping analysis was used to determine the relationship between three polymorphisms in the ER-alpha gene (intron 1 T/C, intron 1 A/G and exon 8 G/A) and primary knee OA. Genotypes of the ER-alpha gene polymorphism were determined by PCR followed by restriction enzyme digestion (PvuII for intron 1 T/C, XbaI for intron 1 A/G, and BtgI for exon 8 G/A polymorphism). There was no significant difference between primary knee OA patients and healthy control individuals in the distribution of any of the genotypes evaluated. However, we found that the allele frequency for the exon 8 G/A BtgI polymorphism (codon 594) was significantly different between primary knee OA patients and control individuals (odds ratio = 1.38, 95% confidence interval = 1.01-1.88; P = 0.044). In haplotype frequency estimation analysis, there was a significant difference between primary knee OA patients and control individuals (degrees of freedom = 7, chi2 = 21.48; P = 0.003). Although the number OA patients studied is small, the present study shows that ER-alpha gene haplotype may be associated with primary knee OA, and genetic variations in the ER-alpha gene may be involved in OA.