Changes in diabetic retinal matrix protein mRNA levels in a common transgenic mouse strain

Recently, all the structural features of non-proliferative diabetic retinopathy have been demonstrated in mice fed 30% galactose for 21-26 months. To determine whether changes in retinal matrix protein mRNA levels occur early in the course of murine diabetes we used a competitive RT-PCR method to quantitate retinal mRNA levels in an inbred mouse strain (FVB) commonly used for transgenic studies. Retinal mRNA was prepared from STZ-diabetic and non-diabetic FVB mice at 4, 8, 12 and 16 weeks and cDNA encoding basement membrane components was quantitated using MIMIC constructs that compete for the same primer pairs. α1 (IV) collagen, the β1 and γ1 chains of laminin, fibronectin, and vitronectin mRNAs were quantitated. For α1 (IV) collagen, statistically significant diabetes-induced increases were apparent by 8 weeks (3.11 ± 0.20 vs. 1.29 ± 0.19 x 10⁶ molecules/μg total RNA, p<0.005). Similarly, diabetes-induced increases were observed by 8 weeks for the β1 chain of laminin (4.54±0.22 vs. 1.85±0.43 x 10⁵ molecules/μg total RNA, p<0.005), the γ1 chain of laminin (7.33±0.29 vs. 4.84±0.76 x 10⁴/μg total RNA, p<0.05), and for fibronectin (2.22±0.21 vs. 1.35±0.15 x 10⁶ molecules/μg total RNA, p<0.05). The magnitude of change was greatest for α1 (IV) collagen (2.4-fold) and β1 laminin (2.5-fold) at 8 weeks, and least for fibronectin (1.6-fold). A smaller diabetes-induced increase in vitronectin mRNA was also observed, but it failed to reach statistical significance at 12 and 16 weeks. These data provide the basis for assessing the effects of genetic manipulation on diabetic retinopathy in transgenic mouse models.