Embryonic stem cells (ESCs) are metabolically distinct from their differentiated counterparts. ESC mitochondria are less complex and fewer in number than their differentiated progeny. However, few studies have examined the proteins responsible for differences in mitochondrial structure and function between ESCs and somatic cells. Therefore, in this study, we aimed to investigate the differences between mitochondrial proteins in these two cell types. We demonstrate that HSP60 is more abundant in mouse ESC mitochondria than in mouse embryonic fibroblasts. Depletion of HSP60 inhibited mouse ESC proliferation and self-renewal, characterized by decreased OCT4 expression. HSP60 depletion also enhanced apoptosis during mouse ESC differentiation into embryoid bodies. Our results suggest that HSP60 expression has an essential role in ESC self-renewal and survival of differentiated cells from ESCs.

BACKGROUND: Congenital adrenal hyperplasia (CAH) results from an inherited defect in enzymatic steps required to synthesize cortisol from cholesterol. 21-hydroxylase deficiency accounts for 95% cases of CAH. It appears that the frequency and the type of the responsible mutations differ according to the ethnic background and the type of mutation can predict the clinical outcomes such as salt losing type (SL), simple virilizing type (SV) and non-classic type (NC). METHODS: We have analyzed CYP21 genes in 55 Korean cases (110 chromosomes) of CAH by Southern blotting, PCR-dot hybridization and PCR amplification-created restriction site method. The patients include 43 cases of SL and 12 of SV. None of the NC was found. RESULTS: We found the mutations in 94% (103/110) of the examined chromosomes. A total of 10 types of mutations were discovered. The mutations include aberrant splicing of intron 2 (i2, 35%), CYP21 gene deletion (32%) and I172N (11%) in order. When the relationship between the clinical types and genotypes were correlated, most of the SL patients have either i2 (42%) or CYP21 gene deletion (41%), while SV patients have I172N (33%) or P30L (21%). The parents' mutation was investigated in 20 cases. In 4 families, one of the parents was not the obligatory heterozygote carrier i.e. did not have a mutation. The results suggest the high incidence of de novo mutation. CONCLUSION: We have identified the frequency of mutations of the CYP21 in Korean AGS patients. Our results shows that the clinical type of AGS can be predicted from the genotypes of CYP21. Also the high incidence of de novo mutation of CYP21 confirmed the genetic instability of major histocompatibility III region where the CYP21 is located.
Adrenal Hyperplasia, Congenital ; Adrenogenital Syndrome* ; Blotting, Southern ; Cholesterol ; Gene Deletion ; Genotype* ; Heterozygote ; Histocompatibility ; Humans ; Hydrocortisone ; Incidence ; Introns ; Parents ; Phenotype* ; Polymerase Chain Reaction ; Steroid 21-Hydroxylase*

The molecular mechanism underlying the initiation of somatic cell reprogramming into induced pluripotent stem cells (iPSCs) has not been well described. Thus, we generated single-cell-derived clones by using a combination of drug-inducible vectors encoding transcription factors (Oct4, Sox2, Klf4 and Myc) and a single-cell expansion strategy. This system achieved a high reprogramming efficiency after metabolic and epigenetic remodeling. Functional analyses of the cloned cells revealed that extracellular signal-regulated kinase (ERK) signaling was downregulated at an early stage of reprogramming and that its inhibition was a driving force for iPSC formation. Among the reprogramming factors, Myc predominantly induced ERK suppression. ERK inhibition upregulated the conversion of somatic cells into iPSCs through concomitant suppression of serum response factor (SRF). Conversely, SRF activation suppressed the reprogramming induced by ERK inhibition and negatively regulated embryonic pluripotency by inducing differentiation via upregulation of immediate early genes, such as c-Jun, c-Fos and EGR1. These data reveal that suppression of the ERK-SRF axis is an initial molecular event that facilitates iPSC formation and may be a useful surrogate marker for cellular reprogramming.