Biology subjects

Ruhanen, H.

Publications and source records attributed to Ruhanen, H..

3 recordsLinked to original sources

bioRxiv2024

Functional omics of ORP7 in primary endothelial cells.

BackgroundMany members of the oxysterol binding protein related protein (ORP) family have been characterized in detail over the past decades, but the lipid transport and other functions of ORP7 still remain elusive. What is known about ORP7 points toward an endoplasmic reticulum and plasma membrane-localized protein, which also interacts with GABARAPL2 and unlipidated LC3B, suggesting a further autophagosomal/lysosomal association. Functional roles of ORP7 have been suggested in cholesterol efflux, hypercholesterolemia, and macroautophagy. We performed a hypothesis-free omics analysis of chemical ORP7 inhibition utilizing transcriptomics and lipidomics as well as proximity biotinylation interactomics to characterize ORP7 functions in a primary cell type, human umbilical vein endothelial cells (HUVECs). Moreover, assays on metrics such as angiogenesis, cholesterol efflux and lipid droplet quantification were conducted. ResultsPharmacological inhibition of ORP7 lead to an increase in gene expression related to lipid metabolism and inflammation, while genes associated with cell cycle and cell division were downregulated. Lipidomic analysis revealed increases in ceramides, lysophosphaditylcholines, as well as saturated and monounsaturated triacylglycerols. Significant decreases were seen in all cholesteryl ester and in some unsaturated triacylglycerol species, compatible with the detected decrease of mean lipid droplet area. Along with the reduced lipid stores, ABCG1-mediated cholesterol efflux and angiogenesis decreased. Interactomics revealed an interaction of ORP7 with AKT1, a central metabolic regulator. ConclusionsThe transcriptomics results suggest an increase in prostanoid as well as oxysterol synthesis, which could be related to the observed upregulation of proinflammatory genes. We envision that the defective angiogenesis in HUVECs subjected to ORP7 inhibition could be the result of an unfavorable plasma membrane lipid composition and/or reduced potential for cell division. To conclude, the present study suggests multifaceted functions of ORP7 in lipid homeostasis, angiogenic tube formation and gene expression of lipid metabolism, inflammation and cell cycle in primary endothelial cells, possibly through AKT1 interaction.

molecular biology↗

bioRxiv2024

Menopause-associated proteomic and lipidomic alterations in high-density lipoprotein: Perimenopause is characterized by smaller triacylglycerols-enriched particles.

High-density lipoprotein particles (HDL) possess anti-inflammatory, anti-thrombotic, cytoprotective, and anti-oxidative properties, thus protecting against cardiovascular diseases. Menopause is associated with changes in serum metabolome and HDL size distribution. We analyzed the protein and lipid composition of the HDL particles from pre-, peri-, and postmenopausal women (N=216) with nuclear magnetic resonance and mass spectrometry to get a deeper insight into the composition of HDL in different stages of menopause. Both particle size and composition differed; in perimenopause, the proportion of small HDL particles (8.7 nm on average) was higher, and the proportion of large HDL particles (12.1 nm on average) was lower than in pre- or postmenopause. In perimenopause, each particle size class was enriched with triacylglycerols, and the calculated lipid class ratio of triacylglycerol/cholesteryl ester was the highest within perimenopausal HDL particles. This potentially affects the HDL interaction with lipid-modifying enzymes. We also observed directionally opposite associations for HDL cholesteryl ester and unesterified cholesterol with systemic estradiol and follicle-stimulating hormone levels, especially regarding S-sized HDL particles, but not the hormone associations with HDL triacylglycerols. Perimenopausal HDL also exhibited a lower proportion of apolipoproteins (apoA-I, apoA-II, apoC-I, apoC-III, apoD and apoE) per particle than premenopausal or postmenopausal HDL. In summary, we found that premenopausal and postmenopausal HDL particles were compositionally similar and differed from perimenopausal ones. We suggest that menopause, and especially the unbalanced hormonal state in perimenopause, are reflected in the lipid and protein compositions of the HDL, which, in turn, may affect the functions of the HDL particle.

molecular biology↗

bioRxiv2023

Seasonal and genetic effects on lipid profiles of juvenile Atlantic salmon

Seasonality can influence many physiological traits requiring optimal energetic capacity for life-history stage transitions. In Atlantic salmon, high-energy status is essential for the initiation of maturation. Atlantic salmon lipid reserves are predominantly found in the viscera and myosepta in the muscle while the liver is essential for maintaining lipid metabolism. A genomic study found a region including a transcription co-factor-coding gene, vgll3, linked to Atlantic salmon maturation timing, which acts as an inhibitor of adipogenesis in mice, and mediates maturation via condition factor in Atlantic salmon. Here we investigate the influence of season and vgll3 genotypes associating with early (EE) and late (LL) maturation on lipid profiles in the muscle and liver in juvenile Atlantic salmon. We reared Atlantic salmon for two years until the occurrence of sexually mature males and sampled muscle and liver at two time points: spring and autumn of the second year. We found no seasonal or genotype effect in lipid profiles in muscle of immature males and females. However, in the liver we did detect a triacylglycerol (TG) enrichment and a genotype specific direction of change in membrane lipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), from spring to autumn. Specifically, from spring to autumn membrane lipid concentrations increased in vgll3*EE individuals and decreased in vgll3*LL individuals. This could be explained with two possible scenarios 1) a seasonally more stable capacity of endoplasmic reticulum (ER) functions in vgll3*EE individuals compared to vgll3*LL individuals or 2) vgll3*LL individuals storing larger lipid droplets from spring to autumn in the liver compared to vgll3*EE individuals at the expense of ER capacity. This genotype specific seasonal direction of change in membrane lipid concentrations provides more indirect evidence that a mechanism linking vgll3 with lipid metabolism and storage exists. HighlightsO_LISeasonal lipid species profile separation in muscle and liver in juvenile Atlantic salmon C_LIO_LIGenotype specific direction of change of membrane lipids from spring to autumn C_LIO_LIIndirect evidence that a mechanism linking vgll3 with lipid metabolism and storage exists C_LI

evolutionary biology↗