Investigating WNT signalling in the lung

Autosomal recessive polycystic kidney disease (ARPKD) is a rare hereditary condition that has been reported to affect approximately one in every 20,000 newborns worldwide. It is caused by a mutation in PKHD1, the gene encoding the protein Fibrocystin (FPC). The primary pathophysiology of ARPKD has been characterized by cystic kidney disease, liver fibrosis, and lung failure. The most severe cases of ARPKD have been observed in neonatal life, with a mortality rate of 30–40%, where the cause of death has been attributed to respiratory distress resulting from lung hypoplasia. If this stage is survived, the chances of long-term survival have been noted to increase to 80%. The specific etiology of this hypoplasia has remained unknown; however, it has been linked to kidney enlargement and oligohydramnios. As a branch of non-canonical WNT signalling, the planar cell polarity (PCP) pathway has emerged as a key ciliary signalling mechanism. Recent studies have highlighted the involvement of core PCP proteins in both ARPKD pathology and lung development and homeostasis. The aim of the study was to determine whether there was a link between non-canonical Wnt signalling and the PKHD1 mutation that was responsible for lung hypoplasia seen in ARPKD patients. Both lung tissue samples from 9-month-old Pkhd1T36M/T36M mice and A549 cells were used in this study. Key proteins from both canonical and non-canonical Wnt pathways were quantified by Western blotting to determine the primary intercellular Wnt signalling pathway associated with lung hypoplasia in ARPKD mutant mouse lungs. Following this, WNT4 and ATMIN single and double knockdowns, as well as WNT11 and PKD2 single and double knockdowns, were performed in A549 cells to assess the interrelationship between these genes and to determine their functional effects in lung epithelial cells. Several cellular functions, including apoptosis, proliferation, adhesion, migration, cell morphology, and actin cytoskeleton expression and localization, were examined. Studies on mouse lungs indicated that the PCP pathway was the primary pathway affected in Pkhd1-mutated mouse lungs, with observed changes in the protein expression of Vangl2 and Scribble. Meanwhile, studies on human lung cell lines suggested that WNT4, ATMIN, WNT11, and PKD2 could be potential regulators of lung development, particularly in branching morphogenesis, alveolar development, and angiogenesis. These findings suggested a contribution to the development of pulmonary hypoplasia in ARPKD patients, in contrast to the initial theory that pulmonary hypoplasia was a secondary effect of cystic and enlarged kidneys. Further investigations will be required to determine the direct involvement of Pkhd1 in lung development. If confirmed, these findings could aid in the development of effective diagnostic tools and therapeutic targets for pulmonary hypoplasia in ARPKD patients.

Citation

Aravindan, R. (2025) Investigating WNT signalling in the lung. University of Wolverhampton. https://wlv.openrepository.com/handle/2436/626006

Publisher

University of Wolverhampton

URI

https://wlv.openrepository.com/handle/2436/626006

Type

Thesis or dissertation

Language

en

Description

A thesis submitted in partial fulfilment of the requirement of the University of Wolverhampton for the degree of Master of Philosophy.

Collections

Theses and Dissertations