Clinical Screening Of CARD9 Gene Mutation And The Study Of CARD9 Protein Structure

Background and PurposeCaspase recruitment domain-containg protein 9(CARD9)is a member of CARD family.CARD9 is one of the most important immune proteins.Many studie have confirmed that the abnormal of CARD9 is related to many disease,such as inflammatory bowel disease,cardiova-scular and tumor.In resent years,many studies have found that mutations in the CARD9 gene are associated with human fungal susceptibility.More and more mutations in the CARD9 gene have been discovered and reported in patients with mycosis.The role of CARD9 in fungal infection has became a hot issue in the study of fungi and host immunity,but little is known about its exact pathogenic mechanism.Therefore,this study aims to carry out CARD9 gene mutation test in patients with relapsed refractory mycosis and severe fungal infection.Study how the CARD9 mutations affect protein structure using the method of computational biology.Bulid the three-dimensional structure of CARD9 protein to further understand the relationship of CARD9 gene mutation and fungal susceptibility.MethodsThis study collected patients with fungal infections,most of whom have the characteristics of prolonged disease course and lack the common predisposing factors.Take the CARD9 gene test using next-generation sequencing.For patients with pathogenic CARD9 mutation,peripheral blood mononuclear cells and neutrophils were extracted for anti-fungal immune function research.Using molecular docking technology to study the impact of the CARD9 gene mutation on the structure of CARD domain,revealing the pathogenic mechanism of the mutation.Bulid the threedimensional structure of CARD9 protein by de novo prediction to further understand the characteristics of CARD9 protein.Results1.In this study,a total of 6 patients were collected.Gene testing revealed that two of them carry the pathogenic mutations of CARD9 gene.2.Immune function study found that the patient with recurrent candida lymphadenitis who carrying mutations of CARD9 gene(c.68C>A,c.820 dup G)has an abnormal ability to kill Candidas.3.The result of molecular dynamics simulations revealed that CARD9 homozygous mutations R18 W,R35Q and R57 H will affect the structure of CARD9-CARD-BCL10 complex.4.The full-length three-dimensional structure of CARD9 protein was obtained by de novo prediction.ConclusionThis study revealed that compound heterozygous mutations of CARD9 gene(c.68C> A,c.820 dup G)can affect the level of cytokines and the function of neutrophils in the immune process against Candida albicans,resulting in repeated illness of the patient.This research explain the effect of CARD9 mutations on the complex structure and construct the full-length three-dimensional spatial structure of CARD9 protein innovatively use the methods of protein structural biology and computational biology,in order to provide the basia for subsequent research.