Intraflagellar transport-A deficiency ameliorates ADPKD renal cystogenesis in a renal tubular- and maturation-dependent manner
Primary cilia are sensory organelles built and maintained by intraflagellar transport (IFT) multi-protein complexes. Deletion of different IFT-B genes attenuates polycystic kidney disease (PKD) severity in juvenile and adult Autosomal Dominant (AD) PKD mouse models, while deletion of an IFT-A adaptor, Tulp3, attenuates PKD severity in adult mice only. These studies indicate that dysfunction of specific cilia components has potential therapeutic value. To broaden our understanding of cilia dysfunction and its therapeutic potential, here we investigate the impact of global deletion of an IFT-A gene, Thm1, in juvenile and adult ADPKD mouse models. Both juvenile and adult models exhibited increased kidney weight:body weight (KW/BW) ratios, renal cysts, inflammation, lengthened renal cilia, and increased levels of the nutrient sensor, O-linked {beta}-N-acetylglucosamine (O-GlcNAc). Thm1 deletion in juvenile ADPKD mice reduced KW/BW ratios and cortical collecting duct cystogenesis, but increased proximal tubular and glomerular dilations and did not reduce inflammation, cilia lengths, and O-GlcNAc signaling. In contrast, Thm1 deletion in adult ADPKD mice markedly attenuated renal cystogenesis, inflammation, cilia lengths, and O-GlcNAc. Thus, unlike IFT-B genes, the role of Thm1 deletion in ADPKD mouse models is development-specific. Unlike an IFT-A adaptor gene, deleting Thm1 in juvenile ADPKD mice is partially ameliorative. Our studies suggest that different microenvironmental factors found in distinct nephron segments and between developing and mature kidneys modify ciliary homeostasis and ADPKD pathobiology. Further, elevated levels of O-GlcNAc, which regulates cellular metabolism and ciliogenesis, may be a novel feature and critical regulator of certain key ADPKD pathological processes.