Abstract: Objective To compare urinary Smad1 and the protein content of Smad1 in renal tissues of patients with diabetic nephropathy (DN) and the patients with other types of nephropathy. Methods According to the result of renal biopsy, the patients were collected and divided into four groups as follows: the patients with diabetes nephropathy(DN group, 9 cases), with focal segmental glomerulosclerosis (FSGS group, 5 cases), with IgA nephropathy (IgA group, 12 cases) and with minimal change nephrosis (MNP group, 10 cases). Urinary Smad1 was examined using ELISA. The expression of Smad1, Col4 and α-SMA in renal tissues was detected by immunohistochemistry and immunofluorescence staining method. Results Urinary Smad1 can be detected in the DN group and there other groups (FSGS group, IgA group and MNP group). The urinary Smad1 from four groups was higher significantly than those from 47 healthy people with routine physical examination (P<0.05). The expression of Smad1 in different area of the renal tissues(the area of glomerulus and renal tubule) can be observed by immuno-histochemistry staining in the patients with four different types of nephropathy. The Smad1 expression in the renal tissue of the patients with diabetes nephropathy was higher than that of three other groups (P<0.05). The co-expression of Col4 and α-SMA with Smad1 in different area of the renal tissues (the area of glomerulus and renal tubule) was found. Conclusions The over-expression of Smad1 in different area of the renal tissues can be observed and is related with renal damage.

Key words: diabetes nephropathy, renal biopsy, Smad1 protein, type Ⅳ collagen protein(Col4), smooth muscle α-actin(α-SAM)