Changqing Liu

Melatonin improves reprogramming efficiency and proliferation of bovine-induced pluripotent stem cells

Melatonin can modulate neural stem cell (NSC) functions such as proliferation and differentiation into NSC‐derived pluripotent stem cells (N‐iPS) in brain tissue, but the effect and mechanism underlying this are unclear. Thus, we studied how primary cultured bovine NSCs isolated from the retinal neural layer could transform into N‐iPS cell. NSCs were exposed to 0.01, 0.1, 1, 10, or 100 μm melatonin, and cell viability studies indicated that 10 μm melatonin can significantly increase cell viability and promote cell proliferation in NSCs in vitro. Thus, 10 μm melatonin was used to study miR‐302/367‐mediated cell reprogramming of NSCs. We noted that this concentration of melatonin increased reprogramming efficiency of N‐iPS cell generation from primary cultured bovine NSCs and that this was mediated by downregulation of apoptosis‐related genes p53 and p21. Then, N‐iPS cells were treated with 1, 10, 100, or 500 μm melatonin, and N‐iPS (M‐N‐iPS) cell proliferation was measured. We noted that 100 μm melatonin increased proliferation of N‐iPS cells via increased phosphorylation of intracellular ERK1/2 via activation of its pathway in M‐N‐iPS via melatonin receptors 1 (MT1). Finally, we verified that N‐iPS cells and M‐N‐iPS cells are similar to typical embryonic stem cells including the expression of pluripotency markers (Oct4 and Nanog), the ability to form teratomas in vivo, and the capacity to differentiate into all three embryonic germ layers.

Reversine Increases the Plasticity of Long-Term Cryopreserved Fibroblasts to Multipotent Progenitor Cells through Activation of Oct4.

Reversine, a purine analog, had been evidenced that it could induce dedifferentiation of differentiated cells into multipotent progenitor cells. Here, we showed that reversine could increase the plasticity of long-term cryopreserved bovine fibroblasts, and reversine-treated cells achieved the ability to differentiate into all three germ layers cells, such as osteoblasts and adipocytes from mesoblast, neurocyte from ectoderm, hepatocytes and smooth muscle cells from endoderm. Moreover, treatment of reversine caused the grow arrest of fibroblasts at G2/M and distinct cell swelling resulting in the formation of polyploid cells. In parallel, reversine treatment induced a multipotency of fibroblasts might be attributed to the activation of histone modifications, especially the degression of DNA methylation. However, molecular and cellular experiments suggested that reversine treatment enhanced selectively the expression of pluripotent marker gene Oct4 and mesenchymal marker genes CD29, CD44 and CD73, but Sox2 and Nanog were not detected. Taken together, these results clearly demonstrate the ability of reversine to dedifferentiation of long-term cryopreserved somatic cells through activation of pluripotent gene Oct4.

Establishment and genetic characteristics analysis of in vitro culture a fibroblast cell line derived from Wuzhishan miniature pig

Establishment of fibroblast cell lines of endangered pig breeds and research on the gene functions based on the cells made a significant contribution to the conservation and utilization of genetic resources. The Wuzhishan miniature pig ear marginal tissue fibroblast cell line (WPF22) from 22 samples, stocking 87 cryogenically-preserved vials, was successfully established by using primary explants technique and cell cryopreservation techniques. WPF22 cells were adherent, with a population doubling time of 30.2h. Chromosome karyotyping and G-banding analysis showed that >90.2% of cells were diploid (2n=38) prior to the 4th generation. Neither microbial contamination nor cross-contamination was detected by isoenzyme analyses. Cell viability was 97.8% before cryopreservation and 94.9% after recovery. To determine cell permeability, intracellular path and stability of exogenous proteins during the transduction, six fluorescent protein genes were transferred into fibroblasts by lipofectamine-mediated method. The transfection efficiency of six fluorescent protein genes fluctuated between 8.1% and 42.6%. ECFP and DsRed were mostly shown in cytoplasmic in dots around the nucleus, and EYFP and EGFP had a slightly stronger expression in the nucleus than in the cytoplasm, but without expression in some vacuoles. Every index of the WPF22 cell line meets all the standard quality controls of American type Culture Collection (ATCC). This research thus does not only preserve important genetic resources of Wuzhishan miniature pig at the cell level, but also serve as a valuable resource for genome, postgenome and somacloning research.

Construction of a full-length enriched cDNA library and preliminary analysis of expressed sequence tags from Bengal Tiger Panthera tigris tigris.

In this study, a full-length enriched cDNA library was successfully constructed from Bengal tiger, Panthera tigris tigris, the most well-known wild Animal. Total RNA was extracted from cultured Bengal tiger fibroblasts in vitro. The titers of primary and amplified libraries were 1.28 × 106 pfu/mL and 1.56 × 109 pfu/mL respectively. The percentage of recombinants from unamplified library was 90.2% and average length of exogenous inserts was 0.98 kb. A total of 212 individual ESTs with sizes ranging from 356 to 1108 bps were then analyzed. The BLASTX score revealed that 48.1% of the sequences were classified as a strong match, 45.3% as nominal and 6.6% as a weak match. Among the ESTs with known putative function, 26.4% ESTs were found to be related to all kinds of metabolisms, 19.3% ESTs to information storage and processing, 11.3% ESTs to posttranslational modification, protein turnover, chaperones, 11.3% ESTs to transport, 9.9% ESTs to signal transducer/cell communication, 9.0% ESTs to structure protein, 3.8% ESTs to cell cycle, and only 6.6% ESTs classified as novel genes. By EST sequencing, a full-length gene coding ferritin was identified and characterized. The recombinant plasmid pET32a-TAT-Ferritin was constructed, coded for the TAT-Ferritin fusion protein with two 6× His-tags in N and C-terminal. After BCA assay, the concentration of soluble Trx-TAT-Ferritin recombinant protein was 2.32 ± 0.12 mg/mL. These results demonstrated that the reliability and representativeness of the cDNA library attained to the requirements of a standard cDNA library. This library provided a useful platform for the functional genome and transcriptome research of Bengal tigers.

Establishment and Characterization of Fibroblast Cell Line Derived from Siberian Tiger (Panthera tigris altaica)

The Siberian tiger ear marginal tissue fibroblast cell line (STF34) from 34 samples was successfully established using primary explants technique and cell cryoconservation technology. STF34 cells were adherent, with a population doubling time of 24 h. Chromosome analysis showed that 90.2%-91.6% of cells were diploid (2n = 38). Isoenzyme analyses of lactate dehydrogenase and malate dehydrogenase showed that STF34 cells had no cross-contamination with other species. Tests for cell line contamination with bacteria, fungi, viruses, and mycoplasmas were all negative. Every index of the STF34 cell line meets all the standard quality controls of American Type Culture Collection. Not only has the germline of this important Siberian tiger species been preserved at the cell level, but also valuable material had been provided for genome, postgenome, and somacloning research.

Generation and analysis of a large-scale expressed sequence tags from a full-length enriched cDNA library of Siberian tiger (Panthera tigris altaica)

In this study, a full-length enriched cDNA library was successfully constructed from Siberian tiger, the worlds most endangered species. The titers of primary and amplified libraries were 1.28×10(6)pfu/mL and 1.59×10(10)pfu/mL respectively. The proportion of recombinants from unamplified library was 91.3% and the average length of exogenous inserts was 1.06kb. A total of 279 individual ESTs with sizes ranging from 316 to 1258bps were then analyzed. Furthermore, 204 unigenes were successfully annotated and involved in 49 functions of the GO classification, cell (175, 85.5%), cellular process (165, 80.9%), and binding (152, 74.5%) are the dominant terms. 198 unigenes were assigned to 156 KEGG pathways, and the pathways with the most representation are metabolic pathways (18, 9.1%). The proportion pattern of each COG subcategory was similar among Panthera tigris altaica, P. tigris tigris and Homo sapiens, and general function prediction only cluster (44, 15.8%) represents the largest group, followed by translation, ribosomal structure and biogenesis (33, 11.8%), replication, recombination and repair (24, 8.6%), and only 7.2% ESTs classified as novel genes. Moreover, the recombinant plasmid pET32a-TAT-COL6A2 was constructed, coded for the Trx-TAT-COL6A2 fusion protein with two 6× His-tags in N and C-terminal. After BCA assay, the concentration of soluble Trx-TAT-COL6A2 recombinant protein was 2.64±0.18mg/mL. This library will provide a useful platform for the functional genome and transcriptome research of for the P. tigris and other felid animals in the future.

Construction and Preliminary Characterization Analysis of Wuzhishan Miniature Pig Bacterial Artificial Chromosome Library with Approximately 8-Fold Genome Equivalent Coverage

Bacterial artificial chromosome (BAC) libraries have been invaluable tools for the genome-wide genetic dissection of complex organisms. Here, we report the construction and characterization of a high-redundancy BAC library from a very valuable pig breed in China, Wuzhishan miniature pig (Sus scrofa), using its blood cells and fibroblasts, respectively. The library contains approximately 153,600 clones ordered in 40 superpools of 10 × 384-deep well microplates. The average insert size of BAC clones was estimated to be 152.3 kb, representing approximately 7.68 genome equivalents of the porcine haploid genome and a 99.93% statistical probability of obtaining at least one clone containing a unique DNA sequence in the library. 19 pairs of microsatellite marker primers covering porcine chromosomes were used for screening the BAC library, which showed that each of these markers was positive in the library; the positive clone number was 2 to 9, and the average number was 7.89, which was consistent with 7.68-fold coverage of the porcine genome. And there were no significant differences of genomic BAC library from blood cells and fibroblast cells. Therefore, we identified 19 microsatellite markers that could potentially be used as genetic markers. As a result, this BAC library will serve as a valuable resource for gene identification, physical mapping, and comparative genomics and large-scale genome sequencing in the porcine.

Isolation and Biological Characterization of a novel type of Pulmonary Mesenchymal Stem Cells derived from Wuzhishan Miniature pig embryo

Pulmonary mesenchymal stem cells (PMSCs) have great potential in lung tissue engineering and represent attractive candidates for disease treatment in human and veterinary research. However, a reliable method for isolation and localization of porcine PMSCs in situ is still uncertain. In this study, we successfully isolated PMSCs from Wuzhishan miniature pig embryos in vitro and also attempted to unravel its fundamental differentiation potential and biological characteristics. The isolated PMSCs, which could be cultured and passaged for at least 15 passages, exhibited a typical fibroblast‐like morphology and high proliferative potential. Moreover, the PMSCs could express pluripotent marker genes (Oct4 and Nanog) and MSCs‐related surface antigens (β‐integrin, CD44, CD71, CD73, CD90, and CD105), while the expressions of CD34 and CD45 were negative. Cell cycle examination showed that the rate of G0/G1 was about 72.1–90.2%. Additionally, the PMSCs not only could be induced to transdifferentiate into mesoblastic cells such as osteoblasts, chondrocytes, and adipocytes in vitro, but also the neural ectoderm and endoderm. Together, these data demonstrate the multiple differentiations potential of PMSCs in vitro, which confers potential use in serving as desirable cell types for lung injury regeneration.

MicroRNAs Regulate the Wnt/Ca2+ Signaling Pathway to Promote the Secretion of Insulin in Pancreatic Nestin-Positive Progenitor Cells

MicroRNAs (miRNAs) are small noncoding RNAs that bind to the 3′-UTR of mRNAs and function mainly in post-transcriptional regulation. MiRNAs have been implicated to play roles in organ development, including that of the pancreas. Many miRNAs, such as miR-375, miR-124, miR-7, miR-21 and miR-221, have been shown to regulate insulin production as well as insulin secretion. However, it is not known whether miRNAs can regulate insulin secretion via the control of intracellular Ca2+ in pancreatic beta cells. In this research, expression profiles of miRNAs and mRNAs were investigated using RNA-sequencing and microarray analysis in chicken pancreatic nestin-positive progenitor cells and differentiated pancreatic beta cells. A number of miRNAs were up-regulated after differentiation of progenitors into beta cells, which regulate cell signaling pathways to control cell function. miR-223 and miR146a were shown to promote insulin secretion from pancreatic beta cells by regulating the concentration of intracellular Ca2+ via the down-regulation of their target genes.

Construction and analysis of Siberian tiger bacterial artificial chromosome library with approximately 6.5-fold genome equivalent coverage.

Bacterial artificial chromosome (BAC) libraries are extremely valuable for the genome-wide genetic dissection of complex organisms. The Siberian tiger, one of the most well-known wild primitive carnivores in China, is an endangered animal. In order to promote research on its genome, a high-redundancy BAC library of the Siberian tiger was constructed and characterized. The library is divided into two sub-libraries prepared from blood cells and two sub-libraries prepared from fibroblasts. This BAC library contains 153,600 individually archived clones; for PCR-based screening of the library, BACs were placed into 40 superpools of 10 × 384-deep well microplates. The average insert size of BAC clones was estimated to be 116.5 kb, representing approximately 6.46 genome equivalents of the haploid genome and affording a 98.86% statistical probability of obtaining at least one clone containing a unique DNA sequence. Screening the library with 19 microsatellite markers and a SRY sequence revealed that each of these markers were present in the library; the average number of positive clones per marker was 6.74 (range 2 to 12), consistent with 6.46 coverage of the tiger genome. Additionally, we identified 72 microsatellite markers that could potentially be used as genetic markers. This BAC library will serve as a valuable resource for physical mapping, comparative genomic study and large-scale genome sequencing in the tiger.