216 COMPLETE REDUCTION OF p53 EXPRESSION BY RNA INTERFERENCE FOLLOWING HETEROZYGOUS KNOCKOUT IN PORCINE FIBROBLASTS

Because p53 has a critical role in regulation of cell cycle and apoptosis in mammals, mutations of p53 often cause various cancers in mammals. Murine models have contributed to our understanding in cancer related to p53 mutations. Mice, however, have different characteristics from humans in many ways. For instance, the short lifespan of the mouse gives rise to limitations in clinical application of the data obtained from this species. Hence, it would be beneficial to establish a more suitable model in species other than the mouse. The porcine model could be an appropriate alternative because pigs share many anatomical and physiological similarities with humans. However, the production of pigs with homozygous knockout (KO) requires years of breeding heterozygous KO animals. Here, we completely reduced the expression level of p53 mRNA and protein in miniature pig fetal fibroblasts using a combination of gene targeting and RNA interference technique. These cells may be used for nuclear transfer to directly produce pigs without expression of the gene of interest. First, we disrupted the exon 2 region of p53 gene to produce p53 heterozygous KO cells. Miniature pig fetal fibroblasts were transfected with the p53 gene targeting vector. After Geneticin treatment for 2 weeks, a total of 48 surviving colonies were screened by PCR, and one was identified as a homologous recombinant (1/48, 2.08%). Second, the p53 shRNA expression vector was introduced into fibroblasts to isolate p53 knockdown (KD) cells. Transfected fibroblasts were treated with Zeocin for 3 weeks, and the shRNA integrations were confirmed by PCR. We obtained p53 KO, KD, and KOKD fibroblasts which involve p53 KO and KD either separately or simultaneously. In mRNA expression based on RT-PCR, p53 KO fibroblasts showed no difference with wild-type control (91.8 v. 100%). However, the expression levels of KD and KOKD cells significantly decreased (35.5 and 34.7%) compared with the control. In p53 protein levels analysed by Western blot, reduction of the protein was observed in p53 KD, whereas no reduction in p53 KO that might be due to heterozygous mutation. Interestingly, no p53 protein was detected in KOKD, suggesting complete reduction of the protein by synergistic effect of KO and KD. In this study, we demonstrated that various expression levels of p53 in porcine fibroblasts could be achieved by gene targeting and RNA interference technique. Moreover, complete abolishment of protein expression is feasible using combination of the 2 techniques. In further research, cloned miniature pigs with various levels of p53 expression or even lacking p53 expression may be produced using the fibroblasts isolated in the present study as nuclear donors. These pigs may provide new animal models and insights in cancer with respect to the effect of p53.

Human antibodies targeting the C-type lectin-like domain of the tumor endothelial cell marker clec14a regulate angiogenic properties in vitro

It has been suggested that clec14a may be involved in tumor angiogenesis. However, a molecular mechanism has not been clearly identified. In this study, we show for the first time that C-type lectin-like domain (CTLD) of clec14a may be important for regulating cell migration and filopodia formation. Using phage display technology, recombinant human antibodies specific to the CTLDs of human and mouse clec14a (clec14a-CTLD (immunoglobulin G) IgG) were selected. Functional assays using the antibodies showed that clec14a-CTLD IgGs specifically blocked endothelial cell migration and tube formation without affecting cell viability or activation. Further, clec14a-CTLD IgGs inhibited clec14a-mediated cell–cell contact by blocking interaction between CTLDs. Finally, clec14a cross-linking by the clec14a-CTLD IgGs significantly downregulated clec14a expression on the surface of endothelial cells. These results strongly suggest that the clec14a-CTLD may be a key domain in angiogenesis, and that clec14a-CTLD IgGs specifically inhibit angiogenesis by modulating CTLD-mediated cell interactions and clec14a expression on the surface of endothelial cells.

41 RAPID PRODUCTION OF α-1,3-GALACTOSYLTRANSFERASE-DEFICIENT MINIATURE PIGS BY NUCLEAR TRANSFER FOLLOWING NEONATAL SKIN BIOPSY AND LOSS OF HETEROZYGOSITY

Production of α-1,3-galactosyltransferase (αGT)-deficient pigs is a fundamental task to overcome hyperacute rejection in pig-to-human xenotransplantation. However, the procedure to produce such pigs requires a great deal of cost, time, and labor. Heterozygote αGT knockout (KO) pigs should be bred at least for 2 generations to ultimately produce homozygote progenies. Here, we show that αGT-deficient miniature pigs could be produced in much reduced time using mitotic recombination in neonatal ear skin fibroblasts. Miniature pig fetal fibroblasts were transfected with αGT-targeting vector and treated with neomycin. Eighty-seven colonies were screened by PCR, and 2 among them were identified as homologous recombinants with monoallelic disruption of αGT (targeting efficiency = 2.3%). One of the two colonies was chosen and used for subsequent NT. In total, 559 nuclear transfer embryos reconstructed with αGT gene-targeted fetal fibroblasts were transferred to 5 surrogate gilts. Three gilts became pregnant and developed to term with 3 live piglets delivered. Being analyzed by PCR, all piglets born were found to be αGT gene targeted. Fibroblasts were isolated from ear skin biopsies of a 10-day-old αGT gene-targeted miniature pig. To increase the number of mitotic recombination that occurs spontaneously during cell proliferation, fibroblasts were cultured for 6 to 8 passages. Then, these cells were treated with IB4-conjugated Dynabeads; IB4 lectin binds to galactose-α-1,3-galactose (αGal), the antigen formed by αGT, and is responsible for hyperacute rejection (HAR). Using a magnetic column, fibroblasts bound to IB4 lectin were removed. Remaining cells lacking αGal were cultured further until colony formation. A total of 22 fibroblast colonies were screened by PCR, and 15 among them were confirmed as loss of heterozygosity (LOH) with biallelic disruption of αGT by mitotic recombination (LOH efficiency = 68%). One of these clonal cultures of αGT-deficient fibroblasts was chosen and used for subsequent NT. In total, 729 nuclear transfer embryos reconstructed with αGT-deficient neonatal ear skin fibroblasts were transferred to 4 surrogate gilts. Two gilts became pregnant, and 3 live piglets were produced. Based on PCR, both αGT alleles were targeted in all piglets born. Only 8 months were required from the production of heterozygote to homozygote KO in contrast to approximately 2 years consumed for conventional breeding of heterozygotes. The present study demonstrates that the time required for the production of αGT-deficient miniature pigs could be reduced significantly by neonatal skin biopsies and subsequent selection of mitotic recombinants. Such a procedure may be beneficial for the production of other homozygote KO animals, especially in species that require substantial periods of gestation such as pigs.

290 EFFECT OF EXOGENOUS Oct4 PROTEIN ON DIRECT CONVERSION OF HUMAN FIBROBLASTS INTO NEURAL STEM CELLS

The generation of neural stem cells (NSC) from somatic cells may provide unlimited source of neuronal cells for autologous transplantation to patients of neurological disorders. Recently, direct conversion of fibroblasts into NSC by epigenetic reprogramming has been reported (Han et al. 2012 Cell Stem Cell 10, 465–472; Thier et al. 2012 Cell Stem Cell 10, 473–479; Ring et al. 2012 Cell Stem Cell 11, 100–109). These reprogrammed cells are referred to as induced neural stem cells (iNSC) and they share the characteristics of NSC in their morphology, molecular marker expressions, and capacity to differentiate into neurons, astrocytes, and oligodendrocytes. One of the procedures to convert fibroblasts into iNSC is restriction of Oct4 activity to the initial phase of reprogramming, while Sox2, Klf4, and c-Myc are constitutively expressed. In the present study, we examined the effect of Oct4 in reprogramming of human fibroblasts into iNSC. Oct4 protein was modified by the addition of poly-arginine protein transduction domain to easily penetrate into the cell membrane. We transduced Oct4 protein, in contrast to the previous reports where the Oct4 gene was virally introduced. First, human fibroblasts were transfected by retroviral vectors carrying the genes encoding Sox2, Klf4, and c-Myc. Then, transfected cells were cultured in ReNcell NSC maintenance medium containing Oct4 protein. After 4 days, Oct4 protein was removed from the medium. With Oct4 protein transduction, 21 flat colonies were formed from 4 × 105 fibroblasts. These colonies were picked and passaged for subculture and later became iNSC. However, in the absence of Oct4 protein, no colonies were obtained from the same number of fibroblasts that were initially plated. Approximately 40 days after transduction of reprogramming factors, cluster of iNSC were obtained. These cells expressed molecular markers of human NSC, including Nestin, Sox2, Pax6, and Blbp. Moreover, these iNSC could differentiate into neurons, astrocytes, and oligodendrocytes in vitro. Results of the present study demonstrate that transduction of exogenous Oct4 protein may be essential to the direct conversion of human fibroblasts into iNSC using a combination of reprogramming factors Sox2, Klf4, and c-Myc.

24 TARGETED DISRUPTION OF ATAXIA-TELANGIECTASIA MUTATED GENE IN MINIATURE PIGS BY SOMATIC CELL NUCLEAR TRANSFER

Ataxia-telangiectasia (A-T) is a genetic disease caused by germline biallelic mutation in the ataxia-telangiectasia mutated gene (ATM) that results in partial or complete loss of ATM expression or activity. A diverse phenotype of the disease includes progressive cerebellar ataxia, oculocutaneous telangiectasias, radiation hypersensitivity, increased cancer incidence, immunodeficiency and chromosomal instability. The frequency of A-T in the United States and United Kingdom has been estimated to be 1:40 000. Heterozygous carriers may also have predisposition to diverse cancers. Although ATM-deficient mice have been produced, none reflects the extent of neurological abnormalities involving the loss of Purkinje cells of the cerebellum seen in patients. Hence, miniature pigs, which are anatomically and physiologically closer to humans, might serve as an alternative model for human A-T. In the present study, we attempted a targeted disruption of ATM in miniature pigs by somatic cell nuclear transfer. Most A-T patients possess mutated ATM with truncation, resulting in prematurely terminated ATM proteins that are highly unstable. To induce the truncation of ATM, we disrupted exon 59 region of ATM that has been known to be critical for ATM kinase activity. Miniature pig fetal fibroblasts were transfected with ATM-targeting vector and treated by neomycin for 2 weeks. A total of 139 colonies were screened by PCR and 3 among them were identified as homologous recombinants with monoallelic disruption of ATM (targeting efficiency = 2.1%). One of the 3 colonies was chosen and used for subsequent nuclear transfer. In total, 611 nuclear transfer embryos reconstructed with ATM-targeted fetal fibroblasts were transferred into 5 surrogate gilts. Two gilts became pregnant and developed to term with a total of 5 live piglets delivered. Being analysed by PCR, all piglets born were found to be ATM gene-targeted. Because conventional murine models of human A-T have provided only limited insights into therapies and pharmacological treatments, the generation of miniature pigs with disrupted ATM will allow new opportunities to more precisely understand A-T and to accelerate discovery of strategies for prevention and treatment of the disease. In addition, such animals may be utilised in studying cancer with respect to the involvement of ATM in cell cycle arrest, DNA repair and apoptosis.

A control theoretic approach to venom immunotherapy with state jumps

We investigate a model-based control method to boost the immune response. We apply this control method to select the appropriate immune response between the Th1 and Th2 responses. The idea of state jump is discussed using hybrid models notation. To implement the control idea we propose physically available methods.

Replacing the rod with the cone transducin subunit decreases sensitivity and accelerates response decay

Cone vision is less sensitive than rod vision. Much of this difference can be attributed to the photoreceptors themselves, but the reason why the cones are less sensitive is still unknown. Recent recordings indicate that one important factor may be a difference in the rate of activation of cone transduction; that is, the rising phase of the cone response per bleached rhodopsin molecule (Rh*) has a smaller slope than the rising phase of the rod response per Rh*, perhaps because some step between Rh* and activation of the phosphodiesterase 6 (PDE6) effector molecule occurs with less gain. Since rods and cones have different G-protein alpha subunits, and since this subunit (Talpha) plays a key role both in the interaction of G-protein with Rh* and the activation of PDE6, we investigated the mechanism of the amplification difference by expressing cone Talpha in rod Talpha-knockout rods to produce so-called GNAT2C mice. We show that rods in GNAT2C mice have decreased sensitivity and a rate of activation half that of wild-type (WT) mouse rods. Furthermore, GNAT2C responses recover more rapidly than WT responses with kinetic parameters resembling those of native mouse cones. Our results show for the first time that part of the difference in sensitivity and response kinetics between rods and cones may be the result of a difference in the G-protein alpha subunit. They also indicate more generally that the molecular nature of G-protein alpha may play an important role in the kinetics of G-protein cascades for metabotropic receptors throughout the body.

64 VALPROIC ACID ENHANCES IN VITRO DEVELOPMENT OF SOMATIC CELL NUCLEAR TRANSFER EMBRYOS IN PIGS

Epigenetic modification influences reprogramming and subsequent development of somatic cell nuclear transfer embryos. Such modification includes an increase of histone acetylation and a decrease of DNA methylation in transferred donor nuclei. Histone deacetylase inhibitors (HDACi) such as trichostatin A (TSA) and valproic acid (VPA) have been known to maintain high cellular levels of histone acetylation. Hence, the treatment of HDACi to NT embryos may increase efficiency of cloning. Indeed, TSA treatment has significantly enhanced the developmental competence of nuclear transfer embryos in several species including pigs (Zhang et al. 2007 Cloning Stem Cells 9, 357-363; Li et al. 2008 Theriogenology 70, 800-808). Valproic acid, another type of HDACi, has often been used to assist reprogramming of somatic cells into induced pluripotent stem cells in mice. In the present study, we tested the potency of VPA compared with TSA on the enhancement of in vitro development in porcine nuclear transfer embryos. Reconstructed embryos were produced by transferring nuclei of adult ear skin fibroblasts into enucleated oocytes. After electrical activation, these embryos were cultured in PZM-3 containing no HDACi (control), 5 mM VPA, or 50 nM TSA for 24 h, and another 5 days thereafter without HDACi. At least 3 replicates were conducted for the following experiments. The rates of cleavage were not different among the VPA, TSA, and control groups. However, the rate of blastocyst development was significantly higher (P < 0.05) in embryos treated with VPA than in those treated with TSA and without HDACi (125/306, 40.8% v. 94/313, 30.0% v. 80/329, 24.3%). Differential staining of inner cell mass (ICM) and trophectoderm (TE) also supported the beneficial effect of VPA treatment in NT embryos. Compared with the control group, the number of TE cells was significantly increased (P < 0.05) in the VPA and TSA treatment groups (79.3 ± 7.4 v. 74.6 ± 9.2 v. 40.0 ± 6.7). Moreover, VPA treatment significantly increased (P < 0.05) the number of ICM cells compared with the control (15.6 ± 1.7 v. 10.8 ± 2.6), whereas no differences were observed between the TSA treatment and control group (12.9 ± 3.0 v. 10.8 ± 2.6). The present study demonstrates that VPA enhances in vitro development of nuclear transfer embryos, in particular by an increase of blastocyst formation and the number of ICM cells, suggesting that VPA may be more potent than TSA in supporting developmental competence of cloned embryos. However, long-term effects of different HDACi in the development of nuclear transfer embryos, including any adverse outcome from destabilizing epigenetic condition, remain to be determined by further in vivo embryo transfer studies.

Intra- and inter-observer reproducibility of volume measurement of knee cartilage segmented from the OAI MR image set using a novel semi-automated segmentation method

OBJECTIVE

We developed a semi-automated method based on a graph-cuts algorithm for segmentation and volumetric measurements of the cartilage from high-resolution knee magnetic resonance (MR) images from the Osteoarthritis Initiative (OAI) database and assessed the intra- and inter-observer reproducibility of measurements obtained via this method.

DESIGN

MR image sets from 20 subjects of varying Kellgren-Lawrence (KL) grades (from 0 to IV) on fixed flexion knee radiographs were selected from the baseline double-echo and steady-state (DESS) knee MR images in the OAI database (0.B.1 Imaging Data set). Two trained radiologists independently performed the segmentation of knee cartilage twice using the semi-automated method. The volumes of segmented cartilage were computed and compared. The intra- and inter-observer reproducibility were determined by means of the coefficient of variation (CV%) of repeated cartilage segmented volume measurements. The subjects were also divided into the low- (0, I or II) and high-KL (III or IV) groups. The differences in cartilage volume measurements and CV% within and between the observers were tested with t tests.

RESULTS

The mean (+/-SD) intra-observer CV% for the 20 cases was 1.29 (+/-1.05)% for observer 1 and 1.67 (+/-1.14)% for observer 2, while the mean (+/-SD) inter-observer CV% was 1.31 (+/-1.26)% for session 1 and 1.79 (+/-1.72)% for session 2. There was no significant difference between the two intra-observer CV%'s (P=0.272) and between the two inter-observer CV%'s (P=0.353). The mean intra-observer CV% of the low-KL group was significantly smaller than that for the high-KL group for observer 1 (0.83 vs 1.86%: P=0.025). The segmentation processing times used by the two observers were significantly different (observer 1 vs 2): (mean 49+/-12 vs 33+/-6min) for session 1 and (49+/-8 vs 32+/-8min) for session 2.

CONCLUSION

The semi-automated graph-cuts method allowed us to segment and measure cartilage from high-resolution 3T MR images of the knee with high intra- and inter-observer reproducibility in subjects with varying severity of OA.