NSPc1 promotes cancer stem cell self-renewal by repressing the synthesis of all-trans retinoic acid via targeting RDH16 in malignant glioma.

Polycomb group (PcG) proteins play an important role in development and stem cell maintenance, and their dysregulation have been closely linked to oncogenesis and cancer stem cell phenotypes. Here, we found that nervous system polycomb 1 (NSPc1) was highly expressed in stem cell-like glioma cells (SLCs). Knockdown of NSPc1 in SLCs resulted in impaired neurosphere formation and self-renewal abilities, down-regulated expression of stemness markers such as NESTIN, CD133 and SOX2, and decreased capacity to propagate subcutaneous xenografts. In contrast, glioma cells overexpressing NSPc1 exhibited a stem cell-like phenotype, up-regulated expression of stemness markers NESTIN, CD133 and SOX2, and an enhanced capacity to propagate subcutaneous xenografts. Furthermore, we identified that NSPc1 epigenetically repressed the expression of retinol dehydrogenase 16 (RDH16) by directly binding to a region upstream (-1073 to -823) of the RDH16 promoter. Next, we confirmed that RDH16 is a stemness suppressor that partially rescues SLCs from the NSPc1-induced increase in neurosphere formation. Finally, we showed that ATRA partly reversed the NSPc1-induced stemness enhancement in SLCs, through mechanisms correlated with an ATRA-dependent decrease in the expression of NSPc1. Thus, our results demonstrate that NSPc1 promotes cancer stem cell self-renewal by repressing the synthesis of ATRA via targeting RDH16 and may provide novel targets for glioma treatment in the future.

An autosomal genomic scan for loci linked to type 2 diabetes in northern Han Chinese.

We report the results of a genome-wide scan conducted in 219 individuals from 34 large multiplex nuclear pedigrees from the northern Han Chinese population at an average resolution of about 10 cM. Nonparametric two-point and multipoint linkage analyses were performed to detect evidence of linkage with type 2 diabetes in this study. On chromosome 1 four regions showed evidence of linkage with type 2 diabetes in northern Han Chinese. Of these regions a marker D1S193 (73 cM) showed evidence of linkage (two-point nonparametric linkage 2.409), and another region (around 190 cM) was a replication of several other studies performed in different ethnic populations. Evidences of linkage have been confirmed by typing additional markers (average distance 1-5 cM) flanking these two positive regions on chromosome 1. We also found indication of linkage with type 2 diabetes on chromosomes 2, 10, 12, 18, 20, and 22 by two-point linkage analyses.

Association study of an SNP combination pattern in the dopaminergic pathway in paranoid schizophrenia: a novel strategy for complex disorders.

Schizophrenia is a common mental disorder with a complex pattern of inheritance. Despite a large number of studies in the past decades, its molecular etiology remains unknown. In this study, we proposed a 'system-thinking' strategy in seeking the combined effect of susceptibility genes for a complex disorder by using paranoid schizophrenia as an example. We genotyped 85 reported single-nucleotide polymorphisms (SNPs) present in 23 genes for the dopamine (DA) metabolism pathway among 83 paranoid schizophrenics and 108 normal controls with detailed clinical and genetic information. We developed two novel multilocus approaches-the potential effective SNP combination pattern and potential effective dynamic effects analysis, by which three susceptibility genotype combinations were found to be associated with schizophrenia. These results were also validated in a family-based cohort consisting of 95 family trios of paranoid schizophrenia. The present findings suggest that the COMT and ALDH3 combination may be the most common type involved in predisposing to schizophrenia. Since the combination blocks the whole pathways for the breakdown of DA and noradrenaline, it is very likely to play a central role in developing paranoid schizophrenia.

Inhibition of LZIP-mediated transcription through direct interaction with a novel host cell factor-like protein.

Host cell factor 1 (HCF-1) is a cellular transcriptional coactivator which coordinates the assembly of enhancer complex through direct interactions with viral and cellular trans-activators such as VP16, Oct-1, LZIP, and GA-binding protein. These interactions are mediated by the beta-propeller domain comprising the first 380 residues of HCF-1 with six kelch repeats. Here we describe the identification and characterization of a novel HCF-like kelch repeat protein, designated HCLP-1. HCLP-1 is a ubiquitously expressed nuclear protein which is composed almost entirely of a six-bladed beta-propeller. HCLP-1 selectively interacts with LZIP but not with VP16. The physical interaction between HCLP-1 and LZIP leads to the repression of the LZIP-dependent transcription. The HCLP-1-binding domain of LZIP maps to residues 109-315, which contain the bZIP DNA-binding motif. Electrophoretic mobility shift assay demonstrates that HCLP-1 indeed interferes with the binding of LZIP to its DNA target. Thus, HCLP-1 serves a transcriptional co-repressor function mediated through its inhibitory interaction with the LZIP transcription factor. Our findings suggest a new mechanism for transcriptional regulation by HCF-like proteins.

The apparent specificity of NotI (5'-GCGGCCGC-3') is enhanced by M.FnuDII or M.BepI methyltransferases (5'-mCGCG-3'): cutting bacterial chromosomes into a few large pieces.

The restriction endonuclease (ENase) NotI is blocked by methylation within its recognition sequence at 5'-GCGGCmCGC-3'. This sensitivity to methylation can be used to enhance the specificity of NotI in vivo and in vitro. Modification by M.FnuDII or M.BepI methyltransferases (MTase) (5'-mCGCG-3') will block NotI (5'-GCGGCCGC-3') cleavage at overlapping MTase/ENase sites 5'-CGCGGCCGC-3' (equivalent to 5'-GCGGCCGCG-3'), and increase the apparent cleavage specificity of NotI about twofold. This 'cross-protection' procedure reduces the number of NotI fragments in the genomes of Escherichia coli and Bacillus subtilis, as resolved by pulsed field electrophoresis. Application of this method to large DNAs in vitro requires the preparation of highly purified DNA MTases.

Construction and screening of Plasmodium falciparum cDNA library.

The HAINAN isolate of Plasmodium falciparum FCC1/HN was cultured in vitro in large quantities. The total parasite mRNA was purified and reverse transcribed into cDNA. The cDNA fragments were inserted into lambda gt11 to construct a P. falciparum FCC1/HN erythrocytic stage cDNA library. Inhibitory monoclonal antibodies (McAbs) M26-32, F6-C2, and F6-D3 were used to screen the cDNA library expressed in E. coli. A total of 27 positive clones were found to react with M26-32 alone and 34 clones with both M26-32 and F6-C2. These expressed proteins may be candidates for use in malaria vaccine.

Cloning and characterization of an abundant Plasmodium knowlesi antigen which cross reacts with Gambian sera.

A 110 kDa Plasmodium knowlesi antigen, termed PK110, has been identified on the basis of messenger RNA abundance in late schizonts. Most Plasmodium genes previously cloned have been identified by immune sera, which have selected immunodominant antigens composed of repeating epitopes. Although PK110 was not selected by immune sera, it also contains amino acid repeats, indicating that this structure may be a common feature of malarial proteins. Determination of 296 codons in the PK110 gene revealed the presence of thirteen tandem repeats of twelve amino acids whose consensus sequence is E E T Q K T V E P E Q T. A termination codon interrupts the fourteenth repeat, indicating that these repeats are at the C-terminus of the protein. Indirect immunofluorescence experiments with sera raised against the lambda gt11 fusion protein indicate that PK110 is present in intra-erythrocytic late schizonts. Cloned PK110 is recognized by Gambian sera, and shares epitopes with Plasmodium ovale. PK110 does not cross react immunologically or by DNA hybridization with Plasmodium falciparum.

Two unique restriction endonucleases from Neisseria lactamica.

Two new site-specific endonucleases, N1a III and N1a IV, have been isolated from Neisseria lactamica. N1a III recognizes the sequence, CATG, and cleaves 3' of the sequence to produce a four base 3' extension. N1a IV recognizes the sequence, GGNNCC, and cleaves between the two N's to produce blunt ended fragments.

A type II restriction endonuclease with an eight nucleotide specificity from Streptomyces fimbriatus.

A new site-specific endonuclease, Sfi I, has been isolated from Streptomyces fimbriatus . This is the first report of a type II restriction endonuclease whose recognition specificity requires eight nucleotides. Sfi I cleaves the sequence, GGCCNNNN / NGGCC , symmetrically to produce a three base, 3' extension.