Reprogramming of germ cells into pluripotency

Abstract

Primordial germ cells (PGCs) are precursors of all gametes, and represent the founder cells of the germline. Although developmental potency is restricted to germ-lineage cells, PGCs can be reprogrammed into a pluripotent state. Specifically, PGCs give rise to germ cell tumors, such as testicular teratomas, in vivo, and to pluripotent stem cells known as embryonic germ cells in vitro. In this review, we highlight the current knowledge on signaling pathways, transcriptional controls, and post-transcriptional controls that govern germ cell differentiation and de-differentiation. These regulatory processes are common in the reprogramming of germ cells and somatic cells, and play a role in the pathogenesis of human germ cell tumors.

Keywords: Primordial germ cell, Embryonic germ cell, Germ cell tumor, Reprogramming, Induced pluripotent stem cell, Small molecule compound, Gene, Signal, Transcription factor

Core tip: Primordial germ cells can be reprogrammed into pluripotent stem cells called as embryonic germ cells in vitro and into pluripotent germ cell tumors in vivo. Germ cell reprogramming can be regulated by signaling pathways, including PI3K/Akt signaling, mitogen-activated protein kinase signaling, transforming growth factor-β signaling, RA signaling. These mechanisms are also involved in somatic cell reprogramming, indicating that there exist common regulatory networks regulating germ and somatic cell reprogramming. On the other hand, regulators for germ cell development prevent germ cell dedifferentiation in unique manners.