bioRxiv ScienceSearch

bioRxiv · 10.1101/2020.09.15.298802

Lipoprotein distribution of Apo CIII glycoforms in healthy men is linked with low TG and increased insulin sensitivity

Abstract

Glycosylation of Apo CIII modulates its function in triglyceride metabolism, and some variants are associated with a protective or pro-atherogenic lipid profile. These associations have been studied in whole plasma Apo CIII proteoforms, but the proportion of Apo CIII proteoforms in individual lipoprotein fractions has been rarely evaluated. In the present study, we aim to measure the relative content of Apo CIII proteoforms in each lipoprotein fraction (VLDL, IDL, LDL and HDL) in a group of healthy subjects as a potential biomarker for triglyceride metabolism, cardiovascular risk and diabetes. Lipoprotein fractions were separated by differential ultracentrifugation of plasma samples. The relative concentrations of seven Apo CIII variants were measured by mass spectrometric immunoassay, and the complete lipoprotein profile was determined by NMR. The results showed high interindividual variability in the distribution of Apo CIII proteoforms across the study population but a uniform proportion in all lipoprotein fractions. Two Apo CIII variants, Apo CIII0b and Apo CIII1d, were negatively correlated with plasma and VLDL triglycerides regardless of VLDL size and were associated with increased LDL size when transported in LDL particles. Apo CIII0b also showed a negative correlation with lipoprotein-insulin resistance score. Therefore, Apo CIII variants can be reliably measured in lipoprotein fractions, and our results suggest that Apo CIII0b and Apo CIII1d have a protective role in triglyceride metabolism and insulin resistance in healthy individuals.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Rodriguez, M., Rehues, P., Iranzo, V., Mora, J., Balsells, C., Guardiola, M., Ribalta, J.. 2020-09-17. Lipoprotein distribution of Apo CIII glycoforms in healthy men is linked with low TG and increased insulin sensitivity. https://doi.org/10.1101/2020.09.15.298802

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

Trans-branching of polyubiquitin chains orchestrates the DNA replication stress response

Polyubiquitin chain geometry dictates functional consequences of ubiquitylation. Although branched polyubiquitin chains are abundant in cells, little is known about their functions. Here we show that branching on the DNA replication factor PCNA, mediated by the ubiquitin-conjugating enzyme UBE2K and involving lysines 63 and 48 of ubiquitin, orchestrates the sequence of events in response to replication stress. By inducing VCP-dependent extraction of PCNA from chromatin, branching promotes re-priming of stalled forks and necessitates a BRCA1-dependent pathway of daughter-strand gap repair. Our study identifies hyper-accumulation of daughter-strand gaps as the mechanistic basis underlying the toxicity of inhibitors of the PCNA-specific isopeptidase, USP1, in BRCA1-deficient cells. Moreover, an unexpected preference of UBE2K to operate in trans suggests a general timing mechanism to organize hierarchies amongst ubiquitin signals.

molecular biology

Impaired proteostasis is an early feature of the diabetic heart in humans and mice

Diabetes and obesity increase cardiac lipid levels leading to cardiomyopathy and heart failure. We hypothesized that intermittent fasting would reduce cardiac lipid levels. Surprisingly, intermittent fasting increased myocardial triglyceride content, but rescued mortality and attenuated cardiomyopathy in mice overexpressing cardiomyocyte acyl-CoA synthetase 1 (MHC-ACSL1). Lipid overload caused cardiomyocyte accumulation of polyubiquitinated protein aggregates containing desmin, a scaffolding intermediate filament protein, which intermittent fasting prevented. Furthermore, intermittent fasting reversed elevated myocardial C16:0 ceramide content, and knockdown of ceramide synthase CerS5 and CerS6 reduced palmitate-induced protein aggregation, highlighting a role for C16:0 ceramides in this pathology. Conversely, impairing aggrephagy with cardiomyocyte-specific p62 ablation induced heart failure in mice fed a high-fat diet, with paradoxically reduced cardiac lipid content. Crucially, non-failing diabetic human hearts also exhibited protein aggregate pathology. Taken together, these results demonstrate that impaired proteostasis characterizes cardiomyopathy from cardiac lipid overload and identify a promising new therapeutic target for this condition.

molecular biology

Spatial profiling and neurovascular communication in the developing and adolescent cortex following prenatal alcohol exposure

Fetal alcohol spectrum disorders (FASD) constitute a wide range of developmental, cognitive, and behavioral impairments caused by prenatal alcohol exposure (PAE). Although neuronal and vascular consequences of PAE have been studied, how alcohol affects the cerebrovasculature within the framework of the neurovascular unit (NVU) across development remains poorly understood. At minimum, the NVU comprises neurons, astrocyte endfeet, and endothelial cells (ECs), which coordinate to maintain brain homeostasis. Here, we used the NanoString Digital Spatial Profiling platform to characterize spatial transcriptomic data from neurons, astrocytes, and ECs from PAE and saccharin (SAC) control cortices at embryonic day 18 (E18) and postnatal day 28 (P28). Differentially expressed genes were then used for Ingenuity Pathway Analysis (IPA) to identify altered biological pathways and perform comparison analyses across developmental time points, while CellChat was used to infer cell cell communication networks. We uncovered thousands of differentially expressed genes and numerous altered pathways and biological processes in PAE cortices across development. Both IPA and CellChat analyses implicated dysregulation of vascular and extracellular matrix (ECM) remodeling, cell adhesion, and neuroinflammatory signaling. CellChat further predicted the loss of several key bidirectional relationships and altered ligand-receptor interactions among neurovascular cell types at E18 and P28. Overall, these findings identify PAE associated alterations in neurovascular gene expression and intercellular signaling across development, providing potential mechanisms by which PAE may disrupt neurodevelopment.

molecular biology