243 REPROGRAMMING OF FIBROBLASTS TO EXPRESS MALE GERM CELL OR MAST CELL FUNCTIONS USING TESTIS OR MAST CELL-DERIVED CELL EXTRACTS

Abstract

The concept of epigenetic reprogramming of a somatic nucleus was supported by the birth of cloned animals and the derivation of embryonic stem cells after nuclear transplantation into oocytes. Moreover, recent studies reported that the direct transformation of one differentiated somatic cell type into another is possible and would be advantageous for producing isogenic replacement cells. In this study, we were able to modulate the cell fate of fibroblasts by introducing cell extracts derived from a mast cell line, RBL-2H3. NIH-3T3 cells were treated with streptolysin O (SLO; 230 ng/mL), which reversibly permeablizes plasma membrane, and incubated for 30 min with the mast cell- derived cell extracts (4 mg/mL). After resealing the membrane of the cells, we incubated the cells for 3 weeks and then analyzed them for the expression of mast cell-specific genes such as MAFA (mast cell function-associated antigen) and FceRI (high-affinity IgE receptor). Our results showed that the cell extracts can activate the expression of mast cell-specific genes, implying that cell extracts can provide regulatory components required for reprogramming the cell fate to initiate a transcriptional program specific for the cell type. Moreover, mast cell-specific degranulation and cell morphology changes were observed in cultured mouse fibroblasts. We could detect mast cell-specific functions even after 15 days of incubation. Next, to induce porcine fibroblasts to take on testis sertoli cell-specific properties, we reversibly permeablized porcine primary fibroblasts with SLO (230 ng/mL) and incubated the cells with porcine testis extracts (4 mg/mL). As expected, in the reprogrammed primary porcine fibroblasts, the porcine testis extracts activated the expression of porcine testis sertoli cell-specific genes including protamine 1 and 2, SOX9, MIS (mullerian inhibitory substance), preproacrosine (ACR), phosphoglycerate kinase-2 (PGK-2), protein C, and c-kit ligand. The male germ cell functions were sustained for more than 10 days after the reprogramming process. Taken together, our data suggest that testis- or mast cell-derived cell extracts can reprogram fibroblasts to express male germ cell or mast cell functions, respectively, supporting the concept that cell extracts can reprogram the genome activity to activate cell-specific gene expression. This work was supported by ARPC (Grant no. 204117-03-1-HD110) in Korea, and by Biogreen 21 program (Grant no. 20050401034658).