The classical form of alpha1-antitrypsin (alpha1AT) deficiency is the most common genetic cause of liver disease in children and emphysema in adults. Liver disease is caused by a gain-of-function mechanism triggered by the retention of aggregated mutant alpha1ATZ the endoplasmic reticulum (ER) of liver cells. Our work has shown that wide variation in the liver disease phenotype among deficient individuals can be explained by genetically- and/or environmentally-determined variation in the relative efficiency of the ER degradation/quality control pathway or of the protective cellular responses activated by ER retention of the mutant protein. Emphysema is caused by a loss-of-function mechanism in which the decrease in alpha1AT molecules available in the lung permits uninhibited proteolytic damage. It is exacerbated by oxidative inactivation of residual alpha1AT function that results from cigarette smoking. However, there is also emerging evidence for marked variability in the lung disease phenotype among alpha1AT-deficient individuals even when cigarette smoking is taken into consideration. In studies over the last three years supported by this grant, we have found that autophagy is one of the mechanisms for degradation of mutant alpha1AT and one of the protective cellular responses activated by ER retention of alpha1ATZ. The autophagic response is a general mechanism whereby cytosol and intracellular organelles, such as ER, are first sequestered from the rest of the cytoplasm by the formation of a vesicle, which then fuses with lysosome for degradation of its contents. It occurs in many cell types, especially during stress states, such as nutrient deprivation, and during the cellular remodeling that accompanies differentiation, morphogenesis and aging. We have also confirmed previous work indicating the alpha1AT is expressed in the respiratory epithelium. Finally, we have established several novel genetically engineered cell culture and transgenic mouse model system including cell lines with inducible expression of alpha1ATZ, an autophagy-deficient cell line with inducible expression of alpha1ATZ and a transgenic mouse model with liver-specific inducible expression of alpha1ATZ. We now propose to use these systems, as well as the GFP-LC3 transgenic mouse which generates fluorescent autophagic vesicles, to provide more information about the mechanisms by which the autophagic response is activated in the alpha1AT-deficient state, and the mechanisms by which autophagy contributes to the disposal of mutant alpha1AT in the ER. We also propose studies designed to determine whether autophagy is induced in the respiratory epithelium and whether there is a reason to believe that the autophagic response plays a role in the variation in liver disease and lung disease phenotypes in alpha1AT deficiency. In the last specific aim, we will use genomic analysis of transgenic mice with inducible expression of alpha1ATZ to provide a comprehensive and unbiased evaluation of how the liver responds to the pathologic state that characterizes alpha1AT deficiency.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL037784-20
Application #
6911610
Study Section
Lung Injury, Repair, and Remodeling Study Section (LIRR)
Program Officer
Croxton, Thomas
Project Start
1986-09-01
Project End
2009-06-30
Budget Start
2005-07-01
Budget End
2006-06-30
Support Year
20
Fiscal Year
2005
Total Cost
$358,750
Indirect Cost
Name
Children's Hosp Pittsburgh/Upmc Health Sys
Department
Type
DUNS #
044304145
City
Pittsburgh
State
PA
Country
United States
Zip Code
15224
Maurice, Nicholas; Perlmutter, David H (2012) Novel treatment strategies for liver disease due to ?1-antitrypsin deficiency. Clin Transl Sci 5:289-94
Hidvegi, Tunda; Ewing, Michael; Hale, Pamela et al. (2010) An autophagy-enhancing drug promotes degradation of mutant alpha1-antitrypsin Z and reduces hepatic fibrosis. Science 329:229-32
Perlmutter, D H (2009) Autophagic disposal of the aggregation-prone protein that causes liver inflammation and carcinogenesis in alpha-1-antitrypsin deficiency. Cell Death Differ 16:39-45
Scott, Craig M; Kruse, Kristina B; Schmidt, Bela Z et al. (2007) ADD66, a gene involved in the endoplasmic reticulum-associated degradation of alpha-1-antitrypsin-Z in yeast, facilitates proteasome activity and assembly. Mol Biol Cell 18:3776-87
Hidvegi, Tunda; Mirnics, Karoly; Hale, Pamela et al. (2007) Regulator of G Signaling 16 is a marker for the distinct endoplasmic reticulum stress state associated with aggregated mutant alpha1-antitrypsin Z in the classical form of alpha1-antitrypsin deficiency. J Biol Chem 282:27769-80
Perlmutter, David H (2006) The role of autophagy in alpha-1-antitrypsin deficiency: a specific cellular response in genetic diseases associated with aggregation-prone proteins. Autophagy 2:258-63
Perlmutter, David H (2006) Pathogenesis of chronic liver injury and hepatocellular carcinoma in alpha-1-antitrypsin deficiency. Pediatr Res 60:233-8
Kamimoto, Takahiro; Shoji, Shisako; Hidvegi, Tunda et al. (2006) Intracellular inclusions containing mutant alpha1-antitrypsin Z are propagated in the absence of autophagic activity. J Biol Chem 281:4467-76
Rudnick, David A; Perlmutter, David H (2005) Alpha-1-antitrypsin deficiency: a new paradigm for hepatocellular carcinoma in genetic liver disease. Hepatology 42:514-21
Hidvegi, Tunda; Schmidt, Bela Z; Hale, Pamela et al. (2005) Accumulation of mutant alpha1-antitrypsin Z in the endoplasmic reticulum activates caspases-4 and -12, NFkappaB, and BAP31 but not the unfolded protein response. J Biol Chem 280:39002-15

Showing the most recent 10 out of 55 publications