Molecular Biology: Open Access

Mixed Inbred FVB;B6 Background Strain Attenuates Kidney Disease and Improves Survival of Gne^M712T/M712T Mice

Abstract

Yadira Valles-Ayoub, Arman Haghighatgoo, Chai Saechao, Zeshan Khokher, Christopher Creencia, Oscar Scremin, Gregory Lawson, DVM, Babak Darvish and Daniel Darvish

Recessive form of Hereditary Inclusion Body Myopathy (HIBM, IBM2, MIM:600737) is an adult onset muscle wasting disorders caused by hypomorphic GNE, the rate-limiting enzyme of sialic acid (Sia) biosynthesis. Unlike human patients, mice bearing the Gne^M712T/M712T genotype in C57BL/6 background strain suffer severe glomerular hematuria, incomplete podocyte development, and do not survive beyond the first few days of life. We crossed heterozygous mice (Gne^M712T/+) of B6 strain with FVB strain mice. In mixed inbred FVB;B6 background, the homozygous mice show attenuated glomerular disease and survive longer (mean survival 22±13 weeks, n=26). Paradoxically, the homozygous mice showed increased total Sia levels in serum (2x control), and Neu5Ac:Neu5Gc ratios are slightly shifted towards Neu5Ac in serum and towards Neu5Gc in muscle tissue. Increase in serum Sia levels may be caused by altered glomerular filtration. This paradoxical increase in serum Sia may contribute to Sia pools of muscle, and exert a potential beneficial effect. In summary, the background strain of mouse model can significantly affect the disease phenotype.