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Cellular bicarbonate accumulation and vesicular proton transport promote calcification in the sea urchin larva.

ABSTRACT: The sea urchin embryo develops a calcitic endoskeleton through intracellular formation of amorphous calcium carbonate (ACC). Intracellular precipitation of ACC, requires [Formula: see text] concentrating as well as proton export mechanisms to promote calcification. These processes are of fundamental importance in biological mineralization, but remain largely unexplored. Here, we demonstrate that the calcifying primary mesenchyme cells (PMCs) use Na⁺/H⁺-exchange (NHE) mechanisms to control cellular pH homeostasis during maintenance of the skeleton. During skeleton re-calcification, pH_i of PMCs is increased accompanied by substantial elevation in intracellular [Formula: see text] mediated by the [Formula: see text] cotransporter Sp_Slc4a10. However, PMCs lower their pH_i regulatory capacities associated with a reduction in NHE activity. Live-cell imaging using green fluorescent protein reporter constructs in combination with intravesicular pH measurements demonstrated alkaline and acidic populations of vesicles in PMCs and extensive trafficking of large V-type H⁺-ATPase (VHA)-rich acidic vesicles in blastocoelar filopodial cells. Pharmacological and gene expression analyses underline a central role of the VHA isoforms Sp_ATP6V0a1, Sp_ATP6V01_1 and Sp_ATPa1-4 for the process of skeleton re-calcification. These results highlight novel pH regulatory strategies in calcifying cells of a marine species with important implications for our understanding of the mineralization process in times of rapid changes in oceanic pH.

SUBMITTER: Hu MY

PROVIDER: S-EPMC7542784 | biostudies-literature |

REPOSITORIES: biostudies-literature

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RBFOX2/GOLIM4 Splicing Axis Activates Vesicular Transport Pathway to Promote Nasopharyngeal Carcinogenesis

Project description:ABSTRACT 20-30% of patients with nasopharyngeal carcinoma (NPC) develop distant metastasis or recurrence leading to poor survival, of which the underlying key molecular events have yet to be addressed. Here we profiled alternative splicing events in 85 NPC samples using transcriptome analysis and revealed that the long isoform of GOLIM4 (-L) with exon-7 was highly expressed in NPC and associated with poor prognosis. Lines of evidence demonstrated the pro-tumorigenic function of GOLIM4-L in NPC cells. We further revealed that RBFOX2 binds to a GGAA motif in exon-7 and promotes its inclusion forming GOLIM4-L. RBFOX2 knockdown suppressed the tumorigenesis of NPC cells, phenocopying GOLIM4-L knockdown, which was significantly rescued by GOLIM4-L overexpression. Moreover, high expression of RBFOX2 was correlated with the exon-7 inclusion of GOLIM4 in NPC biopsies and associated with worse prognosis. Furthermore, we observed that RBFOX2 and GOLIM4 could influence vesicle-mediated transport through maintaining the organization of Golgi apparatus. Finally, we revealed that RAB26 interacted with GOLIM4 and mediated its tumorigenic potentials in NPC cells. Taken together, our findings provide insights into how alternative splicing contributes to NPC development, by highlighting a functional link between GOLIM4-L and its splicing regulator RBFOX2 activating vesicle-mediated transport involving RAB26. Keywords: GOLIM4, RBFOX2, Nasopharyngeal carcinoma (NPC), Alternative splicing, RAB26

2022-06-01 | GSE178195 | GEO

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