Male-pronuclei-specific granulin facilitates somatic cells reprogramming via mitigating excessive cell proliferation and enhancing lysosomal function.

Critical reprogramming factors resided predominantly in the oocyte or male pronucleus can enhance the efficiency or the quality of induced pluripotent stem cells (iPSCs) induction. However, few reprogramming factors exist in the male pronucleus had been verified. Here, we demonstrated that granulin (Grn), a factor enriched specifically in male pronucleus, can significantly improve the generation of iPSCs from mouse fibroblasts. Grn is highly expressed on Day 1, Day 3, Day 14 of reprogramming induced by four Yamanaka factors and functions at the initial stage of reprogramming. Transcriptome analysis indicates that Grn can promote the expression of lysosome-related genes, while inhibit the expression of genes involved in DNA replication and cell cycle at the early reprogramming stage. Further verification determined that Grn suppressed cell proliferation due to the arrest of cell cycle at G2/M phase. Moreover, ectopic Grn can enhance the lysosomes abundance and rescue the efficiency reduction of reprogramming resulted from lysosomal protease inhibition. Taken together, we conclude that Grn serves as an activator for somatic cell reprogramming through mitigating cell hyperproliferation and promoting the function of lysosomes.

WD repeat domain 82 (Wdr82) facilitates mouse iPSCs generation by interfering mitochondrial oxidative phosphorylation and glycolysis.

BACKGROUND: Abundantly expressed factors in the oocyte cytoplasm can remarkably reprogram terminally differentiated germ cells or somatic cells into totipotent state within a short time. However, the mechanism of the different factors underlying the reprogramming process remains uncertain. METHODS: On the basis of Yamanaka factors OSKM induction method, MEF cells were induced and reprogrammed into iPSCs under conditions of the oocyte-derived factor Wdr82 overexpression and/or knockdown, so as to assess the reprogramming efficiency. Meanwhile, the cellular metabolism was monitored and evaluated during the reprogramming process. The plurpotency of the generated iPSCs was confirmed via pluripotent gene expression detection, embryoid body differentiation and chimeric mouse experiment. RESULTS: Here, we show that the oocyte-derived factor Wdr82 promotes the efficiency of MEF reprogramming into iPSCs to a greater degree than the Yamanaka factors OSKM. The Wdr82-expressing iPSC line showed pluripotency to differentiate and transmit genetic material to chimeric offsprings. In contrast, the knocking down of Wdr82 can significantly reduce the efficiency of somatic cell reprogramming. We further demonstrate that the significant suppression of oxidative phosphorylation in mitochondria underlies the molecular mechanism by which Wdr82 promotes the efficiency of somatic cell reprogramming. Our study suggests a link between mitochondrial energy metabolism remodeling and cell fate transition or stem cell function maintenance, which might shed light on the embryonic development and stem cell biology.

Inducing somatic cells into pluripotent stem cells is an important platform to study the mechanism of early embryonic development.

The early embryonic development starts with the totipotent zygote upon fertilization of differentiated sperm and egg, which undergoes a range of reprogramming and transformation to acquire pluripotency. Induced pluripotent stem cells (iPSCs), a nonclonal technique to produce stem cells, are originated from differentiated somatic cells via accomplishment of cell reprogramming, which shares common reprogramming process with early embryonic development. iPSCs are attractive in recent years due to the potentially significant applications in disease modeling, potential value in genetic improvement of husbandry animal, regenerative medicine, and drug screening. This review focuses on introducing the research advance of both somatic cell reprogramming and early embryonic development, indicating that the mechanisms of iPSCs also shares common features with that of early embryonic development in several aspects, such as germ cell factors, DNA methylation, histone modification, and/or X chromosome inactivation. As iPSCs can successfully avoid ethical concerns that are naturally present in the embryos and/or embryonic stem cells, the practicality of somatic cell reprogramming (iPSCs) could provide an insightful platform to elucidate the mechanisms underlying the early embryonic development.