Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.
The peptidyl-prolyl isomerase Pin1 is proposed to have diverse functions in many vital aspects of the cell. Despite the multitude of proteins targeted by Pin1 and the proposed regulatory role it plays in critical cellular functions, Pin1 is an essential gene in some eukaryotic organisms, but is dispensable in metazoans. In two genetic models, Candida albicans and Drosophila melanogaster, Pin1 participates in distinct developmental processes regulated by the MAPK pathway. Pin1-deficient mice exhibit decreased primordial germ cell proliferation during embryonic development, along with several degenerative or proliferative defects in the adult testis, retina, mammary gland, and brain. The combination of primordial germ cell deficit and spermatogonial depletion contributes to severe fertility defects in Pin1-null mice. Since growth factor activated MAPK pathways are vital to germ cell proliferation and differentiation, a role for Pin1 in mammalian germ cell development and spermatogenesis is discussed in the context of the Ras/MEK/MAPK pathway.