Increased decorin mRNA expression leads to larger collagen fibril diameter in SHR kidney cortex

• Published in: The FASEB journal Vol. 24; no. S1; p. 982.3
• Main Authors: Skogstrand, Trude, Leh, Sabine, Moen, Ingrid, Stuhr, Linda Elin Birkhaug, Reed, Rolf, Iversen, Bjarne Magnus, Hultström, Michael
• Format: Journal Article
• Language: English
• Published: Federation of American Societies for Experimental Biology 01-04-2010
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.24.1_supplement.982.3

It has been shown that the renal hypertensive damage in SHR is accompanied by changes in the synthesis, deposition and breakdown of collagen, in particular in the juxtamedullary cortex (JMC). In the present study, we investigated gene expression using Illumina beadarray microarrays comparing renal cortex from 60 week old SHR with WKY rats.
The results showed increased expression of decorin (2.3 fold increase P<0.01). Decorin is a small leucin rich protein (SLRP) which binds collagen and is important in collagen fibril formation. In addition, fibronectin, another SLRP was also increased (1.8 fold increase P<0.01). Finally several forms of fibrillar collagen were upregulated, collagen Ia1 (1.4 fold increase P<0.01), collagen IIIa1 (2.7 fold increase P<0.01) and collagen Ia2 (2.9 fold increase P<0.01). This indicates a changed collagen fibril composition and assembly process.
Further, collagen fibril diameter measurements were performed using TEM. The fibril diameters were increased in the JMC of SHR compared to the outer cortex (P<0.05), while diameters in superficial and juxtamedullary cortex were not different in WKY.
In conclusion, renal interstitial fibrosis in JMC of SHR is composed of thicker collagen fibrils. This increased fibril diameter may be a result of increased SLRP expression in damaged cortex as well as a changed composition of the collagen fibrils.