The carboxy-terminus of the human ARPKD protein fibrocystin can control STAT3 signalling by regulating SRC-activation

Area of Science:

• Biochemistry
• Genetics
• Cell Biology

Background:

• Autosomal recessive polycystic kidney disease (ARPKD) is a genetic disorder primarily linked to mutations in the PKHD1 gene.
• The PKHD1 gene encodes fibrocystin (FC), a transmembrane protein with largely unknown cellular functions.
• Dysregulation of cellular signaling pathways is implicated in the pathogenesis of ARPKD.

Purpose of the Study:

• To investigate the functional role of fibrocystin's cytoplasmic tail in cellular signaling.
• To explore the association between fibrocystin, SRC kinase, and STAT3 signaling in the context of ARPKD.
• To identify potential molecular mechanisms underlying ARPKD pathogenesis related to fibrocystin function.

Main Methods:

• Investigated the interaction between fibrocystin's C-terminal fragment and the SRC/STAT3 signaling module.
• Analyzed genetic variants in the PKHD1 gene, specifically focusing on truncating mutations in the cytoplasmic tail of ARPKD patients.
• Utilized co-immunoprecipitation to detect the physical association between SRC and fibrocystin's cytoplasmic tail.
• Assessed the activation status of SRC and STAT3 in renal epithelial cells from ARPKD patients.

Main Results:

• A C-terminal fragment of fibrocystin was found to suppress the SRC/STAT3 signaling module.
• Truncating variants in the fibrocystin cytoplasmic tail were identified in ARPKD patients.
• SRC and the fibrocystin cytoplasmic tail form a dynamic protein complex.
• Increased activation of SRC and STAT3 was observed in renal epithelial cells from ARPKD patients.

Conclusions:

• Fibrocystin's cytoplasmic tail plays a role in regulating SRC/STAT3 signaling.
• Aberrant SRC/STAT3 activation, potentially due to altered fibrocystin function, contributes to ARPKD.
• Targeting the SRC/STAT3 pathway may offer therapeutic strategies for ARPKD.