Correlation of secreted protein acidic and rich in cysteine with diabetic nephropathy

Abstract

To detect the serum concentrations of secreted protein acidic and rich in cysteine (SPARC) in patients with diabetic nephropathy and SPARC mRNA and protein expressions in renal tissue of db/db mice (C57BL/KsJ, diabetic nephropathy mice), thus preliminary exploration on the role of secreted protein acidic riches in cysteine in the development of diabetic nephropathy were carried out. Serum SPARC levels in normal subjects, patients with type 2 diabetes mellitus (without diabetic nephropathy), chronic renal failure (without diabetes mellitus), and diabetic nephropathy were determined with enzyme-linked immunosorbent assay. 12-week-old db/db mice (db/db group) and its littermate wild-type control mice (NC group) were selected with 6 from each group, and the kidney tissue were taken. RT-PCR, Western blot, and immunofluorescence were used to detect the mRNA, targeted protein expressions of SPARC and the staining of renal tissue. The serum level of SPARC in diabetic nephropathy group was significantly higher than those in normal group, type 2 diabetes mellitus, and chronic renal failure group (P < 0.05 or P < 0.01). The SPARC level in the type 2 diabetes mellitus group was higher than that in normal group (P < 0.05), but there was no difference between normal group and chronic renal failure. SPARC mRNA and protein levels in renal tissue of db/db mice were higher compared with the normal control group (P < 0.05). The long term hyperglycemic state in patients with diabetic nephropathy causes pathological change of renal tissue. Simultaneously, increased secretion of SPARC from renal tissue results in elevation of serum SPARC level. SPARC correlates with the occurrence and progression of diabetes, and it may play a role in pathological change of diabetic nephropathy.

Keywords: Secreted protein acidic and rich in cysteine; diabetic nephropathy; insulin-like growth factor; transforming growth factor β1.

Figure 1

Serum SPARC levels in four groups. Date are expressed as mean (μg/L) ± S.E.M. a. P < 0.01, DN VS Normal; b. P < 0.01, DN VS DM; c. P < 0.05, DN VS CRF; d. P < 0.05, DM VS Normal.

Figure 2

The expression of SPARC mRNA in db/db mice and control mice, ^aP < 0.05, db/db mice vs control mice.

Figure 3

The expression of SPARC in db/db mice and control mice, ^aP < 0.05, db/db vs control mice.

Figure 4

The immunofluorescence stain of kidney tissue of db/db mice and control mice (SPARC positive staining showed green fluorescence, and the more of SPARC content, the stronger of the staining; (A) was the immunofluorescence staining of kidney tissue in control group; (C) showed the immunofluorescence staining of db/db Mice kidneys; (B, D) were respectively the ordinary light microscopy of (A, C). The results showed that kidney tissue staining in db/db group was significantly stronger than that in the NC group, indicating a significant increase in SPARC protein expression in kidney tissue compared with the control group.