Kuninaka, S. | Search bioRxiv

bioRxiv2021

Purinergic receptor P2RY14 cAMP signaling regulates EGFR-driven Schwann cell precursor self-renewal and nerve tumor initiation in neurofibromatosis.

Neurofibromatosis type 1 (NF1) is a genetic disorder characterized by nerve tumors called neurofibromas, in which Schwann cells (SCs) lack NF1 and show deregulated RAS signaling. NF1 is also implicated in regulation of cAMP. Gene expression profiling and protein expression identified P2RY14 in SCs and SC precursors (SCPs) implicating P2RY14 as a candidate upstream regulator of cAMP in EGF-dependent SCP. We found that SCP self-renewal was reduced by genetic or pharmacological inhibition of P2RY14. In NF1 deficient SCs and malignant peripheral nerve sheath tumor (MPNST) cells, P2RY14 inhibition decreased EGFR-driven phospho-Akt and increased cAMP signaling. In a neurofibroma mouse model, genetic deletion of P2RY14 increased mouse survival, delayed neurofibroma initiation and rescued cAMP signaling. Conversely, elevation of cAMP diminished SCP number in vitro and diminished SC proliferation in neurofibroma bearing mice in vivo. These studies identify the purinergic receptor P2RY14 as a critical G-protein-coupled receptor (GPCR) in NF1 mutant SCPs and SCs and suggest roles for EGFR-GPCR crosstalk in facilitating SCP self-renewal and neurofibroma initiation via cAMP and EGFR-driven phospho-Akt.

neuroscience↗

bioRxiv2020

Phosphorylation of the Anaphase Promoting Complex activator CDH1/FZR regulates the transition from Meiosis I to Meiosis II in mouse male germ cell

CDH1/FZR is an activator of Anaphase promoting complex/Cyclosome (APC/C), best known for its role as E3 ubiquitin ligase that drives the cell cycle. APC/C activity is regulated by CDK-mediated phosphorylation of CDH1 during mitotic cell cycle. Although the critical role of CDH1 phosphorylation has been shown mainly in yeast and in vitro cell culture studies, its biological significance in mammalian tissues in vivo remained elusive. Here, we examined the in vivo role of CDH1 phosphorylation using a mouse model, in which non-phosphorylatable substitutions were introduced in the putative CDK-phosphorylation sites of CDH1. Although ablation of CDH1 phosphorylation did not show substantial consequences in mouse somatic tissues, it led to severe testicular defects resulting in male infertility. In the absence of CDH1 phosphorylation, male juvenile germ cells entered meiosis normally but skipped meiosis II producing diploid spermatid-like cells. In aged testis, male germ cells were overall abolished, showing Sertoli cell-only phenotype. The present study demonstrated that phosphorylation of CDH1 is required for temporal regulation of APC/C activity at the transition from meiosis I to meiosis II, and for spermatoginial stem cell maintenance, which raised an insight into the sexual dimorphism of CDH1-regulation in germ cells.

cell biology↗