Abstract: SA-PO676
Unbiased Transcriptional Analysis of the Nail-Patella-Like Renal Disease Inducing LMX1B R246Q Variant Reveals Dysregulation of Several Genes Critical to Homeostasis of Podocytes and the Glomerular Basement Membrane
Session Information
- Pediatric Glomerular Disease
November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Pediatric Nephrology
- 1700 Pediatric Nephrology
Authors
- Lane, Brandon M., Duke University School of Medicine, Durham, North Carolina, United States
- Hall, Gentzon, Duke University School of Medicine, Durham, North Carolina, United States
- Wu, Guanghong, Duke University School of Medicine, Durham, North Carolina, United States
- Chryst-Stangl, Megan, Duke University School of Medicine, Durham, North Carolina, United States
- Spurney, Robert F., Duke University School of Medicine, Durham, North Carolina, United States
- Gbadegesin, Rasheed A., Duke University School of Medicine, Durham, North Carolina, United States
Background
While most genetic variants in LIM Homeobox Transcription Factor 1 Beta (LMX1B) are associated with the development of Nail Patella Syndrome, select variants such as R246Q produce renal limited phenotypes known as Nail Patella Like Renal Disease (NPLRD). Using a targeted analysis of key podocyte genes, we have previously identified several candidates that are downregulated by R246Q in cultured human podocytes. However, a more comprehensive transcriptional analysis is needed to understand the pathological mechanisms driving kidney specific disease development in NPLRD patients and to identify possible theraputic targets.
Methods
Differentiated conditionally immortalized human podocytes cell lines stably overexpressing equivalent levels of wild type LMX1B or the R246Q variant were analyzed using Illumina RNAseq technology.
Results
The analysis of LMX1B R246Q revealed significant reductions in genes that have been previously implicated in renal disease, including SULF1 and CLIC5, (fold changes of -7.6, and -7.1 respectively). These genes as well as FIBIN (-24.1), COL3A1 (-4.6), ODAM (-5.3), TNIP3 (-5.2), PRKG2 (-5.0), RGS5 (-3.3), ADRA1D (-3.1), and CDH11 (-2.8) were the most highly downregulated targets by the R246Q variant in a kidney focused analysis of the data. The most highly upregulated genes include ANKHD1 (2.9), CCL2 (2.1), C8ORF4 (2.1), ST14 (2.0), MMP9 (1.7), MMP2 (1.7), MMP7 (1.7), and CSF2 (1.7). A kidney focused pathway analysis of the transcriptional data in this study revealed that Matrix Metalloproteinase (MMP) inhibition was the top candidate pathway affected.
Conclusion
While downregulation of key podocyte genes was observed in the transcriptional analysis of LMX1B R246Q, the milieu of affected genes suggest additional pathogenic mechanisms may exist. The upregulation of MMP genes as well as a downregulation of critical basement membrane genes including SULF1 and COL3A1 suggests that glomerular basement membrane (GBM) modification is a key component of R246Q mediated renal disease.
Funding
- NIDDK Support