Background: Recent genomewide association study suggested that the top single-nucleotide polymorphism, rs978056, in HECW1 gene (which encodes HECT, C2 and WW domain containing E3 ubiquitin protein ligase 1) associated with the levels of galactose-deficient IgA1 (Gd-IgA1) in IgA nephropathy (IgAN). However, HECW1 expression in IgAN has not yet been examined.
Methods: In the following study, we have enrolled 40 patients with IgAN and 40 healthy controls. The expression level of HECW1, as well as plasma levels of Gd-IgA1 and IgA1, were determined detected.
Results: IgAN patients presented with significantly elevated Gd-IgA1 and IgA1 levels compared with those of the healthy controls (p < .001 and p = .03, respectively). We further divided the patients into two groups according to the median level of HECW1 (0.58). We found the levels of Gd-IgA1 and IgA1 were significantly higher in low HECW1 level group compared with those in high HECW1 level group (p = .02 and p = .04, respectively). And HECW1 mRNA expression had a significant inverse correlation with Gd-IgA1 levels in IgAN patients (r= -0.34, p = .03). It seemed that the risk genotype (rs978056 GG) was associated with reduced HECW1 expression in 80 Han Chinese from Beijing, although the difference was not significant (p = .09). No significant association with clinical and pathological manifestations was observed between patients with high and low levels of HECW1.
Conclusion: We reported for the first time that HECW1 mRNA levels were negatively correlated with Gd-IgA1 levels. Our study points to a new regulatory mechanism of IgAN that can explain the aberrant glycosylation of IgA1.
Keywords: Galactose-deficient IgA1; HECW1 mRNA level; IgA nephropathy; rs978056.