Nozawa, A. | bioRxiv Science

bioRxiv2023

Changes in cell morphology and function induced by NRAS Q61R mutation in lymphatic endothelial cells

Recently, a low-level somatic mutation in NRAS gene (c.182 A > G, Q61R) was identified in the specimens of patients with kaposiform lymphangiomatosis (KLA). However, it is unknown how these low-frequency mutated cells can affect the characterization and surrounding environment of their lesions. To understand the pathogenesis and association of these gene abnormalities, we established NRASQ61R mutated lymphatic endothelial cells (LECs) transfected with lentivirus vector and undertook morphological and functional characterization, protein expression profiling, and metabolome analysis. NRASQ61R human dermal LECs showed poor tube formation and high cell proliferation and migration ability with increasing ratios of mutated cells. Analysis of signaling pathways showed inactivation of the PIK3/AKT/mTOR pathway and hyperactivation of the RAS/MAPK/ERK pathway, which was improved by MEK inhibitor treatment. This study may show the theoretical circumstances in vitro induced by NRASQ61R-mutated cells in the affected lesions of KLA patients.

cell biology↗

bioRxiv2021

Repeated translocation of a supergene underlying rapid sex chromosome turnover in Takifugu fish

Recent studies have revealed a surprising diversity of sex chromosomes in vertebrates. However, the detailed mechanism of their turnover is still elusive. To understand this process, it is necessary to compare closely related species in terms of sex-determining genes and the chromosomes harboring them. Here, we explored the genus Takifugu, in which one strong candidate sex-determining gene, Amhr2, has been identified. To trace the processes involved in transitions in the sex determination system in this genus, we studied 12 species and found that while the Amhr2 locus likely determines sex in the majority of Takifugu species, three species have acquired sex-determining loci at different chromosomal locations. Nevertheless, the generation of genome assemblies for the three species revealed that they share a portion of the male-specific supergene that contains a candidate sex-determining gene, GsdfY, along with genes that potentially play a role in male fitness. The shared supergene span approximately 100 kb and are flanked by two duplicated regions characterized by CACTA transposable elements. These results suggest that the shared supergene has taken over the role of sex-determining locus from Amhr2 in lineages leading to the three species, and repeated translocations of the supergene underlie the turnover of sex chromosomes in these lineages. These findings highlight the underestimated role of a mobile supergene in the turnover of sex chromosomes in vertebrates. SignificanceAlthough turnover of sex chromosomes is very common in many vertebrate lineages, the transition process is still elusive. We studied the sex-determining region (SDR) of 12 congeneric fish species. We found that while nine species retained their ancestral SDR, three species had acquired derived SDRs. Although the derived SDRs resided in three different chromosomes, they harbored a shared supergene flanked by two putative transposable elements. The results highlight the underestimated role of a mobile supergene in turnover of sex chromosomes in vertebrates.

genomics↗