Folliculin controls lung alveolar enlargement and epithelial cell survival through E-cadherin, LKB1, and AMPK

Cell Rep. 2014 Apr 24;7(2):412-423. doi: 10.1016/j.celrep.2014.03.025. Epub 2014 Apr 13.

Abstract

Spontaneous pneumothoraces due to lung cyst rupture afflict patients with the rare disease Birt-Hogg-Dubé (BHD) syndrome, which is caused by mutations of the tumor suppressor gene folliculin (FLCN). The underlying mechanism of the lung manifestations in BHD is unclear. We show that BHD lungs exhibit increased alveolar epithelial cell apoptosis and that Flcn deletion in mouse lung epithelium leads to cell apoptosis, alveolar enlargement, and an impairment of both epithelial barrier and overall lung function. We find that Flcn-null epithelial cell apoptosis is the result of impaired AMPK activation and increased cleaved caspase-3. AMPK activator LKB1 and E-cadherin are downregulated by Flcn loss and restored by its expression. Correspondingly, Flcn-null cell survival is rescued by the AMPK activator AICAR or constitutively active AMPK. AICAR also improves lung condition of Flcn(f/f):SP-C-Cre mice. Our data suggest that lung cysts in BHD may result from an underlying defect in alveolar epithelial cell survival, attributable to FLCN regulation of the E-cadherin-LKB1-AMPK axis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases / genetics
  • AMP-Activated Protein Kinases / metabolism
  • Animals
  • Apoptosis*
  • Birt-Hogg-Dube Syndrome / metabolism*
  • Birt-Hogg-Dube Syndrome / pathology
  • Cadherins / genetics
  • Cadherins / metabolism
  • Cell Line, Tumor
  • Cell Survival
  • Gene Deletion
  • Humans
  • Mice
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Pulmonary Alveoli / metabolism*
  • Pulmonary Alveoli / pathology
  • Rats
  • Respiratory Mucosa / metabolism*
  • Respiratory Mucosa / pathology
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism*

Substances

  • Bhd protein, mouse
  • Cadherins
  • Proto-Oncogene Proteins
  • Tumor Suppressor Proteins
  • Stk11 protein, mouse
  • Protein-Serine-Threonine Kinases
  • AMP-Activated Protein Kinases