Deciphering the Impact of RAC1-SPTAN1 in ARPKD Cystogenesis Using Multifaceted Models.

Area of Science:

• Nephrology
• Genetics
• Molecular Biology

Background:

• Autosomal recessive polycystic kidney disease (ARPKD) causes severe kidney cysts and dysfunction, lacking effective treatments.
• Current mouse models fail to fully replicate human ARPKD cystic phenotypes.
• Novel models are crucial for understanding ARPKD pathogenesis and identifying therapeutic targets.

Purpose of the Study:

• To investigate the molecular mechanisms underlying ARPKD cyst formation.
• To identify novel therapeutic targets for ARPKD.
• To develop and utilize advanced models for ARPKD research.

Main Methods:

• Development of kidney organoid-on-chip models mimicking patient distal-nephron cysts.
• Utilized transgenic mice and patient kidney samples for validation.
• Employed transcriptomics, live imaging, single-cell RNA-seq, and CRISPR activation.

Main Results:

• Reduced SPTAN1 levels were identified as a key regulator of RAC1 activation and ARPKD pathology.
• SPTAN1 deficiency led to distal-nephron cysts, elevated RAC1/c-FOS, and altered calcium signaling.
• CRISPR-mediated SPTAN1 restoration in models ameliorated cystic phenotypes and normalized molecular pathways.

Conclusions:

• SPTAN1 is a critical factor in ARPKD pathogenesis, regulating cyst development.
• Altered calcium signaling and RAC1/c-FOS activation are central to ARPKD.
• Epigenome editing targeting SPTAN1 shows therapeutic potential for ARPKD.