👤 Ilya Chuykin

FGF receptors play pivotal roles in morphogenetic processes, including vertebrate neurulation. Planar cell polarity signaling coordinates cell orientation in the tissue plane and is essential for neural tube closure. Here, we demonstrate abnormal planar polarity in the Xenopus neuroectoderm depleted of FGFR1, suggesting a mechanistic connection between FGFR signaling and morphogenesis. FGFR1 associates with the core planar cell polarity protein Vangl2, leading to its phosphorylation at N-terminal tyrosines, a modification also induced by FGF8. Vangl2 phosphorylation requires FGFR1 activity in Xenopus embryos and mouse embryonic stem cells, extending our observations to mammals. A non-phosphorylatable Vangl2 construct exhibits increased binding to the receptor tyrosine kinase PTK7, suggesting a potential role of Vangl2 phosphorylation. By contrast, a phosphomimetic Vangl2 mutant shows reduced interactions with Prickle and PTK7, and disrupted planar polarity in the neuroectoderm. Together, these findings identify cross-talk between the FGFR1 and planar cell polarity pathways mediated by Vangl2 tyrosine phosphorylation. Show less

FGF receptors (FGFR) play pivotal roles in morphogenetic processes including vertebrate neurulation. Planar cell polarity (PCP) signaling coordinates cell polarization in tissue plane and also plays an essential role in neural tube closure. Here we demonstrate abnormal PCP in Show less

Spermatogenesis is driven by an ordered series of events, which rely on trafficking of specific proteins between nucleus and cytoplasm. The karyopherin α family of proteins mediates movement of specific cargo proteins when bound to karyopherin β. Karyopherin α genes have distinct expression patterns in mouse testis, implying they may have unique roles during mammalian spermatogenesis. Here, we use a loss-of-function approach to determine specifically the role of Kpna6 in spermatogenesis and male fertility. We show that ablation of Kpna6 in male mice leads to infertility and has multiple cumulative effects on both germ cells and Sertoli cells. Kpna6-deficient mice exhibit impaired Sertoli cell function, including loss of Sertoli cells and a compromised nuclear localization of the androgen receptor. Furthermore, our data demonstrate devastating defects on spermiogenesis, including incomplete sperm maturation and a massive reduction in sperm number, accompanied by disturbed histone-protamine exchange, differential localization of the transcriptional regulator BRWD1 and altered expression of RFX2 target genes. Our work uncovers an essential role of Kpna6 in spermatogenesis and, hence, in male fertility. Show less