Third-year graduate student Farhana Taher Sumya (CBP track) is the first author of the article “Development and Initial Characterization of Cellular Models for COG Complex-Related CDG-II Diseases” in the journal Frontiers in Genetics.
Farhana used CRISPR/Cas9 gene-editing approach to create novel cellular models for two human COG4 mutations (G516R and R729W). Constructed isogenic RPE1 and HEK293T cell lines were comprehensively characterized using biochemical, microscopy (superresolution and electron), and proteomics approaches. The analysis revealed similar stability and localization of COG complex subunits, wild-type cell growth, and normal Golgi morphology in all three cell lines. Importantly, COG4-G516R cells demonstrated increased HPA-647 lectin binding to the plasma membrane glycoconjugates, while COG4-R729W cells revealed high GNL-647 lectin binding, indicating specific defects in O- and N-glycosylation. Both mutant cell lines express the elevated level of heparin sulfate proteoglycans. Moreover, a quantitative mass-spectrometry analysis of proteins secreted by COG-deficient cell lines revealed abnormal secretion of SIL1 and ERGIC-53 proteins by COG4-G516R cells. Interestingly, the clinical phenotype of patients with congenital mutations in SIL1 gene (Marinesco-Sjogren syndrome) overlaps with the phenotype of COG4-G516R patients (Saul-Wilson syndrome). This work is the first compressive study involving the creation of different COG mutations in human cell lines other than the patient’s fibroblast. It may help to address the underlying cause of the phenotypic defects leading to the discovery of a proper treatment guideline for COG-CDGs.
The senior author of the study is Dr. Vladimir Lupashin (Physiology and Cell Biology), in collaboration with Irina Pokrovskaya, M.S. (Physiology and Cell Biology).
A huge congrats to Farhana and the Lupashin lab on all their hard work!