Misexpression of the Niemann-Pick disease type C1 (NPC1)-like protein in Arabidopsis causes sphingolipid accumulation and reproductive defects

Abstract

Misexpression of the AtNPC1 - 1 and AtNPC1 - 2 genes leads to altered sphingolipid metabolism, growth impairment, and male reproductive defects in a hemizygous Arabidopsis thaliana (L.) double-mutant population. Abolishing the expression of both gene copies has lethal effects. Niemann-Pick disease type C1 is a lysosomal storage disorder caused by mutations in the NPC1 gene. At the cellular level, the disorder is characterized by the accumulation of storage lipids and lipid trafficking defects. The Arabidopsis thaliana genome contains two genes (At1g42470 and At4g38350) with weak homology to mammalian NPC1. The corresponding proteins have 11 predicted membrane-spanning regions and contain a putative sterol-sensing domain. The At1g42470 protein is localized to the plasma membrane, while At4g38350 protein has a dual localization in the plasma and tonoplast membranes. A phenotypic analysis of T-DNA insertion mutants indicated that At1g42470 and At4g38350 (designated AtNPC1-1 and AtNPC1-2, respectively) have partially redundant functions and are essential for plant reproductive viability and development. Homozygous plants impaired in the expression of both genes were not recoverable. Plants of a hemizygous AtNPC1-1/atnpc1-1/atnpc1-2/atnpc1-2 population were severely dwarfed and exhibited male gametophytic defects. These gene disruptions did not have an effect on sterol concentrations; however, hemizygous AtNPC1-1/atnpc1-1/atnpc1-2/atnpc1-2 mutants had increased fatty acid amounts. Among these, fatty acid α-hydroxytetracosanoic acid (h24:0) occurs in plant sphingolipids. Follow-up analyses confirmed the accumulation of significantly increased levels of sphingolipids (assayed as hydrolyzed sphingoid base component) in the hemizygous double-mutant population. Certain effects of NPC1 misexpression may be common across divergent lineages of eukaryotes (sphingolipid accumulation), while other defects (sterol accumulation) may occur only in certain groups of eukaryotic organisms.

Adaptations to High Salt in a Halophilic Protist: Differential Expression and Gene Acquisitions through Duplications and Gene Transfers

“…These proteins all encoded at least one sterol-sensing domain (PFAM12349) that potentially monitors the free sterol level in the membrane (Li et al, 2016). Since NPC1 proteins might also be involved in the transport of sphingolipids (Malathi et al, 2004; Lloyd-Evans and Platt, 2010; Feldman et al, 2015), repression of these genes in H. seosinensis indicated that transport of lipids, sterol or sphingolipid, was affected.…”

Soybean Haplotype Map (GmHapMap): A Universal Resource for Soybean Translational and Functional Genomics

“…Using this enhanced SNP catalog and a multi-locus mixed-model implementation, a very strong association ( p -value = 4.2×10 −14 and q -value < 0.001) with a SNP residing in the NPC1 (Niemann-Pick C1) gene ( Glyma.14g001500 ) ( Figure 2B ) was detected. An Arabidopsis mutant of this gene ( npc1 ) exhibits a 58% higher fatty acid content (Feldman et al 2015) making this gene a likely candidate contributing to total oil content in soybean. This demonstrates that the increased number of informative SNP loci, obtained through the imputation of untyped variants, can prove highly beneficial in studying the genetic architecture of complex agronomic traits in soybean.…”

“…To illustrate the benefits of the GmHapMap resource for GWAS, we performed an association analysis on soybean seed oil content using imputed SNPs. A strong association with an imputed SNP residing in the NPC1 gene was detected and its orthologue in Arabidopsis is known to contribute to seed oil content (Feldman et al 2015). Several studies in human (Li et al 2009), cattle (Santana et al 2014), pig (Yan et al 2017), maize (Yang et al 2014) and rice (Wang et al 2018) have demonstrated the capacity of imputation to improve the power of GWAS analysis.…”

Microautophagy in Plants: Consideration of Its Molecular Mechanism

“…Form membrane rafts on the vacuolar membrane by transporting sterol during microlipophagy both in the stationary phase and in acute nitrogen starvation in yeast. [23] NPC1 [45] VTC complex Vtc1, Vtc2, Vtc3, Vtc4…”