Characterization, expression profiles, intracellular distribution and association analysis of porcine PNAS-4 gene with production traits

Comprehensive analysis of expression profile reveals the ubiquitous distribution of PPPDE peptidase domain 1, a Golgi apparatus component, and its implications in clinical cancer

PPPDE peptidase domain 1 (PPPDE1) is a recently identified gene; however, its expression regulation and biological function are unclear. Previous studies have indicated that PPPDE1 is involved in embryogenesis, apoptosis induction and cell cycle regulation. In the present study, we first used an anti-PPPDE1 antibody to determine that endogenous PPPDE1 is located in the Golgi apparatus. Immunohistochemistry (IHC) of mouse embryos indicated that PPPDE1 was markedly distributed in liver, skin, intestinal villi, and muscles, whereas Western blot analysis of mouse mature organs revealed its ubiquitous expression, without an appreciable distinction in protein abundance. Surprisingly, another potential isoform of PPPDE1 with a molecular weight of 18 kD (rather than its predicted molecular weight of 21 kD) was detected in the mouse kidney, testis, and intestine. Moreover, microarrays that were derived from twelve tumor types revealed that PPPDE1 expression was significantly lower in pancreas, stomach, and skin tumors compared with normal tissue from these organs. We specifically and extensively analyzed PPPDE1 expression in clinical samples and observed strong associations between PPPDE1 expression and (i) differentiation grade in pancreatic ductal adenocarcinoma and (ii) T stage in skin squamous cell carcinoma. Our data are the first to reveal the expression profile of PPPDE1 protein and its implications in cancer. These results will contribute to the understanding of the expression regulation and biological functions of PPPDE1 in development and carcinogenesis.

Expression of hPNAS-4 radiosensitizes Lewis lung cancer

PURPOSE

This study aimed to transfer the hPNAS-4 gene, a novel apoptosis-related human gene, into Lewis lung cancer (LL2) and observe its radiosensitive effect on radiation therapy in vitro and in vivo.

METHODS AND MATERIALS

The hPNAS-4 gene was transfected into LL2 cells, and its expression was detected via western blot. Colony formation assay and flow cytometry were used to detect the growth and apoptosis of cells treated with irradiation/PNAS-4 in vitro. The hPNAS-4 gene was transferred into LL2-bearing mice through tail vein injection of the liposome/gene complex. The tumor volumes were recorded after radiation therapy. Proliferating cell nuclear antigen (PCNA) immunohistochemistry staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay were performed to detect the tumor cell growth and apoptosis in vivo.

RESULTS

The hPNAS-4 gene was successfully transferred into LL2 cells and tumor tissue, and its overexpressions were confirmed via western blot analysis. Compared with the control, empty plasmid, hPNAS-4, radiation, and empty plasmid plus radiation groups, the hPNAS-4 plus radiation group more significantly inhibited growth and enhanced apoptosis of LL2 cells in vitro and in vivo (P<.05).

CONCLUSIONS

The hPNAS-4 gene was successfully transferred into LL2 cells and tumor tissue and was expressed in both LL2 cell and tumor tissue. The hPNAS-4 gene therapy significantly enhanced growth inhibition and apoptosis of LL2 tumor cells by radiation therapy in vitro and in vivo. Therefore, it may be a potential radiosensitive treatment of radiation therapy for lung cancer.

Expression profiling of functional genes in prenatal skeletal muscle tissue in Duroc and Pietrain pigs

In livestock, skeletal muscle is a tissue of major economic importance for meat production and muscle mass is largely determined during the prenatal period by the number and the size of muscle fibres. The understanding of gene expression changes during prenatal pig muscle development is still limited. In this study, genes identified as differentially expressed in a previous microarray research and chosen for the function of the coded protein as putative candidate involved in myogenesis were considered to analyse their expression profile during foetal growth of Duroc and Pietrain pigs. The eleven genes were considered by real-time PCR for a time-course evaluation of the transcription level at six stages of prenatal longissimus dorsi development. The results suggest that the most relevant variations in mRNA levels of the analysed genes seem to follow temporal waves of gene expression. Significant changes of transcription were observed at 21-35 and 63-91 days, the two main phases of skeletal muscle development. During the early phases of Pietrain embryos' development, 10 of the 11 genes showed an induction. In Duroc embryos, a second phase of gene up-regulation can be identified in the phase 63-77 days. These results provide new data on developmental changes of expression profile of 11 genes involved in different functional pathways related to prenatal myogenic processes in Duroc and Pietrain pigs.

Prokaryotic expression, purification and characterization of a novel pro-apoptosis protein hPNAS-4

Recently, hPNAS-4 [human PNAS-4; also known as C1orf121 (Genbank accession number NP-057160)] was reported to be a novel pro-apoptotic protein in mammalian cells. However, at present there is little information about hPNAS-4 and its molecular mechanisms. In our present studies, the hPNAS-4 gene was first cloned into the pGEX-6p-1 vector with a GST (glutathione transferase) tag to express in soluble form in Escherichia coli induced with 0.5 mM IPTG (isopropyl beta-D-thiogalactoside) at 25 degrees C, and the recombinant hPNAS-4 was purified to near homogeneity with 96% purity by affinity chromatography and anion-exchange chromatography. The purified hPNAS-4 protein was further identified by liquid chromatography-ESI (electrospray ionization)-MS analysis and used to raise polyclonal antibodies that could specifically recognize the hPNAS-4 protein. In addition, hPNAS-4 is localized to the cytoplasm and the perinuclear compartment. Furthermore, the overexpression of hPNAS-4 in human A549 lung cancer cells resulted in decrease of cell viability via apoptosis. This study represented an important step to investigate the characterization for the new pro-apoptosis protein hPNAS-4, which should aid the discovery of new drug targets for the development of effective therapeutic approaches to cancer in the future.

Improved therapeutic efficacy against murine carcinoma by combining honokiol with gene therapy of PNAS-4, a novel pro-apoptotic gene

PNAS-4, a novel pro-apoptotic gene activated during the early response to DNA damage, can inhibit proliferation via apoptosis when overexpressed in some tumor cells. Recent studies have indicated that honokiol can induce apoptosis, inhibit angiogenesis, and suppress tumor growth. In the present study, we investigated whether mouse PNAS-4 (mPNAS-4) could augment the apoptosis of tumor cells induced by honokiol in vitro, and whether the antiangiogenic activity of honokiol and induction of apoptosis by mPNAS-4 could work cooperatively to improve the antitumor efficacy in vivo. In vitro, mPNAS-4 inhibited proliferation of murine colorectal carcinoma CT26 and Lewis lung carcinoma LL2 cells through induction of apoptosis, and significantly augmented the apoptosis of CT26 and LL2 cells induced by honokiol. Compared with treatment with mPNAS-4 or honokiol alone, in vivo systemic administration of an expression plasmid encoding mPNAS-4 and low-dose honokiol significantly suppressed tumor growth through the enhanced induction of apoptosis and the augmented inhibition of angiogenesis. Our data suggest that the combined treatment with mPNAS-4 plus honokiol augments antitumor effects in vitro and in vivo, and that the improved antitumor activity in vivo may be associated with enhanced induction of apoptosis and augmented inhibition of angiogenesis. The present study may provide a novel and effective method for the treatment of cancer.

Molecular cloning, expression patterns and subcellular localization of porcine TMCO1 gene

The product of transmembrane and coiled-coil domains 1 (TMCO1) gene is a member of DUF841 superfamily of several eukaryotic proteins with unknown function. The partial DNA sequence of porcine TMCO1 was first cloned with a pig 567 bp ORF encoding 188 amino acids. By tissues expression analysis, the TMCO1 was found highly expressed in the liver, kidney and heart. The porcine TMCO1 protein was subsequently demonstrated to localize in the mitochondrion by confocal fluorescence microscopy. This data provides an important basis for conducing further studies on the functions and regulatory mechanisms underlying the role of TMCO1 gene.