Gene expression by simian virus 40 large Tantigen-induced medulloblastomas in mice

Signaling pathways known to have components with mutations in human medulloblastoma include sonic hedgehog, Wnt/beta-catenin and insulin-like growth factor. Microarray analysis was applied to examine the gene expression changes in medulloblastomas of pTet-on/pTRE-SV40Tag transgenic mice. Altogether, 14 112 genes were detectable, including 152 genes with significantly different expression levels. These genes were associated with immunity, the cell cycle, signal transduction, cytoskeleton and metabolism. To further confirm the microarray data, real-time polymerase chain reactions were used to examine the expression changes of genes related to sonic hedgehog, Wnt/beta-catenin and insulin-like growth factor signal pathways. Immunohistochemistry detected insulin receptor substrate-1 in the nuclei of brain tumor tissue cells from pTet-on/pTRE-SV40Tag transgenic mice, suggesting that SV40 large T antigen may activate the insulin-like growth factor signal pathway to promote tumorigenesis.

Establishment of cell lines with porcine spermatogonial stem cell properties

Background:Spermatogonial stem cells(SSCs)are capable of both self-renewal and differentiation to mature functional spermatozoa,being the only adult stem cells in the males that can transmit genetic information to the next generation.Porcine SSCs hold great value in transgenic pig production and in establishment of porcine models for regenerative medicine.However,studies and applications of porcine SSCs have been greatly hampered by the low number of SSCs in the testis as well as the lack of an ideal stable long-term culture system to propagate porcine SSCs perpetually.Results:In the present study,by lentiviral transduction of plasmids expressing the simian virus 40(SV40)large T antigen into porcine primary SSCs,we developed two immortalized cell lines with porcine SSC attributes.The established cell lines,with the expression of porcine SSC and germ cell markers UCHL1,PLZF,THY1,VASA and DAZL,could respond to retinoic acid(RA),and could colonize the recipient mouse testis without tumor formation after transplantation.The cell lines displayed infinite proliferation potential,and have now been cultured for more than 7 months and passaged for over 35 times without morphological abnormalities.Conclusions:We have for the first time established porcine SSC lines that could provide abundant cell sources for mechanistic studies on porcine SSC self-renewal and differentiation,thereby facilitating development of an optimal long-term culture system for porcine primary SSCs and their application to animal husbandry and medicine.

Reversibly immortalized keratinocytes(iKera)facilitate re-epithelization and skin wound healing:Potential applications in cell-based skin tissue engineering

Skin injury is repaired through a multi-phase wound healing process of tissue granulation and re-epithelialization.Any failure in the healing process may lead to chronic non-healing wounds or abnormal scar formation.Although significant progress has been made in developing novel scaffolds and/or cell-based therapeutic strategies to promote wound healing,effective management of large chronic skin wounds remains a clinical challenge.Keratinocytes are critical to re-epithelialization and wound healing.Here,we investigated whether exogenous keratinocytes,in combination with a citrate-based scaffold,enhanced skin wound healing.We first established reversibly immortalized mouse keratinocytes(iKera),and confirmed that the iKera cells expressed keratinocyte markers,and were responsive to UVB treatment,and were non-tumorigenic.In a proof-of-principle experiment,we demonstrated that iKera cells embedded in citrate-based scaffold PPCN provided more effective re-epithelialization and cutaneous wound healing than that of either PPCN or iKera cells alone,in a mouse skin wound model.Thus,these results demonstrate that iKera cells may serve as a valuable skin epithelial source when,combining with appropriate biocompatible scaffolds,to investigate cutaneous wound healing and skin regeneration.