Pompe disease is caused by autosomal recessive mutations in the acid alpha-glucosidase (GAA) gene, which encodes GAA. Although enzyme replacement therapy has recently improved patient survival greatly, the results in skeletal muscles and for advanced disease are still not satisfactory. Here, we report the derivation of Pompe disease-induced pluripotent stem cells (PomD-iPSCs) from two patients with different GAA mutations and their potential for pathogenesis modeling, drug testing and disease marker identification. PomDiPSCs maintained pluripotent features and had low GAA activity and high glycogen content. Cardiomyocyte-like cells (CMLCs) differentiated from PomD-iPSCs recapitulated the hallmark Pompe disease pathophysiological phenotypes, including high levels of glycogen and multiple ultrastructural aberrances. Drug rescue assessment showed that exposure of PomD-iPSC-derived CMLCs to recombinant human GAA reversed the major pathologic phenotypes. Furthermore, L-carnitine treatment reduced defective cellular respiration in the diseased cells. By comparative transcriptome analysis, we identified glycogen metabolism, lysosome and mitochondria-related marker genes whose expression robustly correlated with the therapeutic effect of drug treatment in PomD-iPSC-derived CMLCs. Collectively, these results demonstrate that PomDiPSCs are a promising in vitro disease model for the development of novel therapeutic strategies for Pompe disease.

Figure 1. Nuclear GRP75 physically interacts with RAR/RXR in differentiated NB cells.

Figure 2. A model delineating the GRP75-mediated regulation of RA-elicited neuronal differentiation through direct interaction with RAR/RXR and the structure modeling predicting interaction interfaces between GRP75 and RAR/RXR.

Retinoic acid (RA) has been approved for the differentiation therapy of neuroblastoma (NB). Previous work revealed a correlation between glucose-regulated protein 75 (GRP75) and the RA-elicited neuronal differentiation of NB cells. The present study further demonstrated that GRP75 translocates into the nucleus and physically interacts with retinoid receptors (RAR and RXR) to augment RA-elicited neuronal differentiation. GRP75 was required for RAR/RXR-mediated transcriptional regulation and was shown to reduce the proteasome-mediated degradation of RAR/RXRin a RA-dependent manner. More intriguingly, the level of GRP75/RAR/RXR tripartite complexes was tightly associated with the RA-induced suppression of tumor growth in animals and the histological grade of differentiation in human NB tumors. The formation of GRP75/RAR/RXR complexes was intimately correlated with a normal MYCN copy number of NB tumors, possibly implicating a favorable prognosis of NB tumors. The present findings reveal a novel function of nucleus-localized GRP75 in actively promoting neuronal differentiation, delineating the mode of action for the differentiation therapy of NB by RA.
(PLoS One, 6(10): e26236, 2011.)

Zebrafish (Danio rerio) is used to be a model system for the in vivo studies in the biomedical area. To expend the research scope of physical biochemical and physiological studies, a cold tolerance model of zebrafish is developed. The common carp (Cyprinus carpio) muscle form creatine kinase (CK, EC 2.7.3.2) has been realized as an enzyme which maintained the enzyme activity around 15 oC. At the same time, a cold inducible promoter of zebrafish HSC70 is able to increase the expression of gene product for 9.8 folds at the same temperature range. To construct these two molecular and transgenesis into zebrafish provide a cold tolerance model fish. The transgenic zebrafish can keep its swimming behavior at 13 oC. The swimming distance is 42% increase in 13 oC. This model fish is benefit for the studies of ectothermal vertibrete in low temperature.