Biology subjects

Kiyoi, T.

Publications and source records attributed to Kiyoi, T..

2 recordsLinked to original sources

bioRxiv2024

PIKFYVE inhibition induces endosome- and lysosome-derived vacuole enlargement via ammonium accumulation

FYVE-type zinc finger-containing phosphoinositide kinase (PIKFYVE), that is essential for PtdIns(3,5)P2 production, is an important regulator of lysosomal homeostasis. PIKFYVE dysfunction leads to cytoplasmic vacuolization; however, the underlying mechanism remains unknown. In this study, we explored the cause of vacuole enlargement upon PIKFYVE inhibition in DU145 prostate cancer cells. Enlargement of vacuoles by PIKFYVE inhibition required glutamine and its metabolism by glutaminases. Addition of ammonia, a metabolite of glutamine, was sufficient to enlarge vacuoles via PIKFYVE inhibition. Moreover, PIKFYVE inhibition led to intracellular ammonium accumulation. Endosome-lysosome permeabilization resulted in ammonium leakage from the cells, indicating ammonium accumulation in the endosomes and lysosomes. Ammonium accumulation and vacuole expansion were suppressed by the lysosomal lumen neutralization. It is therefore assumed that PIKFYVE inhibition interferes with the efflux of NH4+, which is protonated NH3 in the lysosomal lumen, leading to osmotic swelling of vacuoles. Notably, glutamine or ammonium is required for PIKFYVE inhibition-induced suppression of lysosomal function and autophagic flux. In conclusion, this study showed that PIKfyve inhibition disrupts lysosomal homeostasis via ammonium accumulation. Summary statementInhibition of the phosphoinositide kinase PIKFYVE results in endosome/lysosome enlargement and impaired lysosomal function. This study showed that the accumulation of glutamine-derived ammonium is the cause of these events.

cell biology↗

bioRxiv2021

Highly concentrated trehalose induces transient senescence-associated secretory phenotype in fibroblasts via CDKN1A/p21

Trehalose is the nonreducing disaccharide of glucose, evolutionarily conserved in invertebrates, but does not exist in vertebrates. The living skin equivalent (LSE) is an organotypic coculture containing keratinocytes cultivated on fibroblast-populated dermal substitutes. We demonstrated that human primary fibroblasts treated with highly concentrated trehalose promote significantly extensive spread of the epidermal layer of LSE without any deleterious effects. The RNA-seq analysis data and Ingenuity pathway analysis of the differentially expressed genes of trehalose-treated 2D and 3D fibroblasts at early time points revealed the involvement of the CDKN1A pathway, which is necessary for the marked upregulation of growth factors including DPT. By contrast, the mRNA-seq data of LSEs 2-weeks after air exposure indicated that gene expression profiles are similar for untreated and trehalose-treated cells in both keratinocytes and fibroblasts. The trehalose-treated fibroblasts were positive for senescence-associated {beta}-galactosidase with the significantly downregulated expressions of LMNB1. Finally, we demonstrated that transplantation of the dermal substitute with trehalose-treated fibroblasts accelerated wound closure and increased capillary formation significantly in the experimental mouse wounds in vivo. These data indicate that high-concentration trehalose can induce the beneficial senescence-associated secretory phenotype in fibroblasts via CDKN1A/p21, which may be therapeutically useful for optimal wound repair.

cell biology↗