Comparative RNA-Seq transcriptome analyses of diabetic nerve and kidney disease

Treating insulin resistance with pioglitazone normalizes renal function and improves small nerve fibre function and architecture; however, it does not affect large myelinated nerve fibre function in mouse models of type 2 diabetes (T2DM), indicating that pioglitazone affects the body in a tissue-specific manner. To identify distinct molecular pathways regulating diabetic peripheral neuropathy (DPN) and nephropathy (DN), as well those affected by pioglitazone, we assessed DPN and DN gene transcript expression in control and diabetic mice with or without pioglitazone treatment. Differential expression analysis and self-organizing maps were then used in parallel to analyse transcriptome data. Differential expression analysis showed that gene expression promoting cell death and the inflammatory response was reversed in the kidney glomeruli but unchanged or exacerbated in sciatic nerve by pioglitazone. Self-organizing map analysis revealed that mitochondrial dysfunction was normalized in kidney and nerve by treatment; however, conserved pathways were opposite in their directionality of regulation. Collectively, our data suggest inflammation may drive large fibre dysfunction, while mitochondrial dysfunction may drive small fibre dysfunction in T2DM. Moreover, targeting both of these pathways is likely to improve DN. This study supports growing evidence that systemic metabolic changes in T2DM are associated with distinct tissue-specific metabolic reprogramming in kidney and nerve and that these changes play a critical role in DN and small fibre DPN pathogenesis. These data also highlight the potential dangers of a 'one size fits all' approach to T2DM therapeutics, as the same drug may simultaneously alleviate one complication while exacerbating another. PMID: 28272773 Overall design: mRNA profiles of four diabetic complication-prone tissues (sciatic nerve, dorsal root ganglia, kidney glomeruli and kidney cortex) from 16-week old BKS.Cg-m +/+ Leprdb/J mice with/without pioglitazone treatment of 15 mg/kg for 11 weeks. db/db genetic model was used for type 2 diabetes model. Deep sequencing of six biological replicates in each tissues using Illumina HiSeq 2000.

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Hinder LM, Park M, Rumora AE, Hur J, Eichinger F, Pennathur S, Kretzler M, Brosius FC 3rd, Feldman EL