Structure analysis of the protein transduction domain of human Period1 and its mutant analogs

Human Period1 (hPer1) has been proved to be able to translocate into cells in a protein transduction manner. The segment of amino acids 830-845 of hPer1 is its protein transduction domain (PTD). In order to explore the membrane penetrating mechanism of hPer1-PTD and the physico-chemical properties necessary in the process, Ala scanning mutation method was used to investigate the variation in the peptide internalization. To further investigate the related physico-chemical requirements, the three dimensional structures of hPer1-PTD and its mutant analogs were simulated by Rosetta method. The electrostatic potentials and energies of these structures were calculated using the Delphi algorithm to solve Poisson-Boltzman equation. The hydrophobicity was assessed by the percentage of the nonpolar area in SAS (solvent accessible surface (SAS)). It has been proved that the Arg836 was the key residue for peptide internalization. When this Arg mutated into Ala, the peptide could not cross the membrane. The large enough area with positive charge was the decisive factor for hPer1-PTD. The alpha-helical structure seemed to play an assistant role so as to enable the positive charge connected in spatial arrangement.

Protein transduction domain of membrane penetrating peptide can efficiently deliver DNA and protein into mouse liver for gene therapy

BACKGROUND

The development of a harmless and efficient nonviral gene delivery system that can facilitate the penetration of nucleic acids through the plasma membrane is a key to successful gene therapy. The aim of this study was to test a nonviral gene transferring vector's function of delivering DNA into liver cells to provide an important clue for gene transfer in liver gene therapy.

METHODS

The complex of DNA and DNA delivering protein was injected into mice through their tail veins. Then the mice were killed and their liver tissue was sectioned. The gene transferring results were detected using a confocal laser scanning microscope.

RESULTS

Fluorescence analysis indicated that both DNA-membrane penetrating peptide (MPP) complex and DNA- hepatocyte specific receptor binding domain (HSRBD)-MPP complex could go into liver cells. The fluorescence value of liver cells in the DNA- HSRBD-MPP group was higher than that in the DNA-MPP group.

CONCLUSIONS

MPP can successfully deliver DNA and protein into cells, and MPP with a HSRBD can specifically deliver DNA into liver cells. These have laid a foundation for further study on the nonviral liver cell gene delivering system.

[Functional analysis of the CPS I upstream sequences with a CAT assay]

Expression plasmids (pKCPSx-CAT) containing carbamyl phosphate synthetase I (CPS I) upstream sequences of different lengths were constructed, and the function and characteristics of the sequences were studied with the CAT assay. The results showed that the CPS I upstream sequences exerted highly tissue-specific control on CPS I gene expression, and the -142- -38bp region relative to the cap site was found to be indispensable for CPS I gene transcription. The -1700- -161bp region contains sequences which confer an enhancing effect on CPS I gene transcription. Dexamethasone and thioproline (a differentiation inducer) showed enhancing effects on CPS I gene transcription in hepatoma cells. These results would have significance in studies on the gene regulation of CPS I associated with the mechanism of hepatocyte differentiation and carcinogenesis.

[Construction of the mammalian expression systems in hepatoma and non-liver cells with rat CPSI cDNA fragments]

Studies on recombination of 0.587 kb and 0.712 kb CPSI cDNA fragments with pSV2 vecter and recombinant pSV2-CPS505 and pSV2-CPS507 plasmid expression of CPSI in non-liver culture cells were presented. The results confirmed that the NIH/3T3 and 7402 hepatoma culture cells transfected individually with pSV2-CPS505 and pSV2-CPS507 plasmid were able to express CPSI effectively. The non-translational sequence is not indispensible to the highly tissue specific expression of CPS I. The studies provided experimental evidence and a cellular model for expression of novel CPSI in vitro, which has a great significance for carcinogenesis and differentiation.

[Expression of rat CPSI full-length cDNA gene in non-liver culture cells]

The full-length CPSI cDNA gene (5.65kb in length) was recombined with pSV2 expression vector, and the recombinant pSV2-CPScf plasmid was expressed CPSI in 7402 hepatoma, CHO and NIH/3T3 cell lines. The pSV2-CPScf plasmid was able to express CPSI protein stably and effectively in all three cell lines. The transcriptional product was identified by Northern blot and nuclear 'runoff' transcription in vitro to be full length CPSI mRNA. Post-transcription and translation processing were found to be not indispensible for the tissue-specific control of CPSI gene expression. This study also provides evidence of large molecular cDNA gene expression using the pSV2 vector and provides cultured cell lines producing CPSI protein in non-liver cells.

Functional analysis of the CPS I upstream sequences with a cat assay

Expression plasmids (pKCPS-CAT) containing carbamyl phosphate synthetase (CPS I) upstream sequences of different lengths were constructed, and the function and characteristics of the sequences were studied with the CAT assay. Results showed that the CPS I upstream sequences exerted highly tissue-specific control on CPS I gene expression, and the -113 approximately -38 bp region relative to the cap site was found to be indispensable for CPS I gene transcription. The -1700 approximately -161 bp region contains sequences which confer an enhancing effect on CPS I gene transcription. Dexamethasone and thioproline (a differentiation inducer) showed enhancing effects on CPS I gene transcription in hepatoma cells. These results would have significance in studies on the gene regulation of CPS I associated with the mechanism of hepatocyte differentiation and carcinogenesis.

[Chemical constituents of Swertia tetraptera Maxim. var. xinglongensis Ji Ma et R. N. Zhao]

Five natural products were isolated from S. tetraptera var. xinglongensis of which four were proved to be oleanolic acid, 1,3-dihydroxy-4,7-dimethoxyxanthone, 1-hydroxy-2,3,5-trimethoxyxanthone and beta-sitosterol. 1,3-dihydroxy-4,7-dimethoxyxanthone has been obtained for the first time from the genus Swertia.