PhD Scientific Days 2024

Poster Session E - Molecular Medicine 2.

Severity Ranking of Stearyl-CoA Sesaturase-1 Missense Mutations by In Silico and In Vitro Methods

Text of the abstract

Nowadays, due to the nutritional habits of developed and developing countries, the prevalence of syndromes connected to disturbances in lipid metabolism, such as obesity-related diseases and metabolic syndrome, is globally increasing.

The key enzyme to maintaining lipid homeostasis is stearoyl-CoA-desaturase-1 (SCD1), which catalyzes the first cis-double bond in the acyl-CoA chain, though have an essential role both supplying fat storage and contributing to cellular defense against lipotoxicity. The expression of SCD1 is regulated at several levels, but the modulating effect of genetic variations must also be considered.

The present work aims to investigate whether naturally occurring missense mutations in SCD1 can affect the expression or function of the enzyme.

The in silico impact and 3D structure of missense variants in SCD1 were predicted using ten different prediction programs and the I-Tasser software, respectively, and analyzed in vitro in a cell culture system. Changes in mutation-dependent SCD1 and ER stress markers were monitored by immunoblotting at the protein level and by qPCR at the mRNA level. The fatty acid profile was investigated by MS.

Based on our results, a severity ranking of the effect of SCD1 missense mutations can be established from deleterious to mild. The c.253AfsTer7 insertion mutation leads to significant changes in protein structure, activity, and quantity, as well as in ER stress, thus proved to have the most damaging effect. p.H125P variant showed significantly reduced protein abundance and desaturation activity with mild ER stress due to the adverse structural change predicted in silico. The p.A333T had only a moderately deleterious effect; a reduced enzyme activity and expression profile were observed, even though neither significant change in the enzyme structure was predicted, and no signs of ER stress were detected. In contrast, p.M224L did not cause any changes in the tested parameters and slightly increased protein production.

Our results suggest that naturally occurring missense variations in SCD1 can cause varying degrees of change in the quantity and function of the enzyme.

This work was supported by FK_138115 and ÚNKP-23-3-I grants.