SCIeNTIfIC REPORTs | 7: 16776 | DOI:10.1038/s41598-017-16603-y
RNA-seq of serial kidney biopsies
obtained during progression
of chronic kidney disease from
dogs with X-linked hereditary
Candice P. Chu
, Jessica A. Hokamp
, Rachel E. Cianciolo
, Alan R. Dabney
, George E. Lees
& Mary B. Nabity
Dogs with X-linked hereditary nephropathy (XLHN) have a glomerular basement membrane defect
that leads to progressive juvenile-onset renal failure. Their disease is analogous to Alport syndrome in
humans, and they also serve as a good model of progressive chronic kidney disease (CKD). However, the
gene expression prole that aects progression in this disease has only been partially characterized.
To help ll this gap, we used RNA sequencing to identify dierentially expressed genes (DEGs), over-
represented pathways, and upstream regulators that contribute to kidney disease progression. Total
RNA from kidney biopsies was isolated at 3 clinical time points from 3 males with rapidly-progressing
CKD, 3 males with slowly-progressing CKD, and 2 age-matched controls. We identied 70 DEGs by
comparing rapid and slow groups at specic time points. Based on time course analysis, 1,947 DEGs
were identied over the 3 time points revealing upregulation of inammatory pathways: integrin
signaling, T cell activation, and chemokine and cytokine signaling pathways. T cell inltration was
veried by immunohistochemistry. TGF-β1 was identied as the primary upstream regulator. These
results provide new insights into the underlying molecular mechanisms of disease progression in XLHN,
and the identied DEGs can be potential biomarkers and therapeutic targets translatable to all CKDs.
X-linked hereditary nephropathy (XLHN) in dogs leads to chronic kidney disease (CKD) because of a
defect in type IV collagen in the glomerular basement membrane (GBM). In the XLHN dogs in this study, a
naturally-occurring, 10-base-pair deletion in the COL4A5 gene located on the X chromosome results in the ina-
bility to synthesize complete α5 chains
. is alteration in the type IV collagen network compromises the struc-
ture and function of the GBM in both aected (hemizygous) males and, to a lesser extent, carrier (heterozygous)
XLHN in dogs is analogous to Alport syndrome (AS) in humans, as approximately 85% of people with AS
have an X-linked mutation in COL4A5
. AS is characterized by juvenile-onset CKD, ocular abnormalities, and
hearing loss in aected males
. us far, only the renal abnormalities have been detected in XLHN dogs
. In dogs
with XLHN, juvenile-onset CKD manifests as persistent proteinuria of glomerular origin as early as 3–6 months
of age, followed by decreasing glomerular ltration rate and worsening azotemia, typically leading to end-stage
renal failure before 1 year of age
Although XLHN has been studied as an example of canine CKD caused by glomerular disease and as an
animal model of human AS
, the gene expression profile that affects progression has only been partially
Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M
University, College Station, TX, USA.
Department of Veterinary Biosciences, College of Veterinary Medicine, The
Ohio State University, Columbus, OH, USA.
Department of Statistics, College of Science, Texas A&M University,
College Station, TX, USA.
Department of Veterinary Integrative Biomedical Sciences, College of Veterinary Medicine
and Biomedical Sciences, Texas A&M University, College Station, TX, USA.
Department of Small Animal Clinical
Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA.
Correspondence and requests for materials should be addressed to M.B.N. (email: firstname.lastname@example.org)
Received: 2 May 2017
Accepted: 25 October 2017
Published: xx xx xxxx