Accumulation of unfolded Z alpha1-antitrypsin inside the endoplasmic reticulum (ER) induces ER proteotoxic stress and increases the incidence of liver injury, fibrosis/cirrhosis and carcinogenesis. Alpha1-antitrypsin deficiency (AATD) is the most common genetic cause of metabolic liver disease in children and the most frequent inherited indication for liver failure and transplantation in the pediatric population, However, the clinical course of AATD-related liver disease is highly variable5, 6, 7.Epidemiological studies of PiZ AATD give rise to three outstanding questions in the field: (1) What are the mechanisms of adaptation to the misfolded AAT accumulation inside the lumen of the endoplasmic reticulum (ER) ? (2) Do the mechanisms of adaption specifically target misfolded AAT or do they also target other unfolded proteins? and (3) Can we design therapeutic strategies to activate these adaptive mechanisms to induce protection? Misfolded proteins within the ER lumen usually trigger adaptive measures termed the unfolded protein response (UPR). However, accumulation of the AAT mutant polymers only activates a modest UPR. The major objective of this project is to explore a novel adaptive mechanism that regulates ER proteotoxic stress by N6-adenosine-methyltransferase 14 (METTL14) at the epitranscriptional level, and thereby translate this novel mechanism to a therapeutic strategy by elevating m6A mRNA modification using an FDA approved drug, entacapone. Thus, the applicant will test the central hypothesis that METTL14, induced by unfolded AAT accumulation, suppresses cell death and hepatotoxicity (Aim 1) by modulating pro-apoptotic transcription factor CHOP m6A modification (Aim2). Aim 1: Determine the protective role of METTL14 in response to AAT deficiency. Our preliminary studies showed that METTL14 liver-specific knockout mice (METTL14Alb) are more susceptible to AAT deficiency-induced liver injury. Here, we will further determine the role of the METTL14 in AATD-induced liver injury by Adeno-Associated Virus (AAV)-METTL14 injection (Aim1.1). Moreover, a FDA approved drug, entacapone, will be evaluated in treatment of AAT deficiency induced liver injury through elevating the m6A mRNA modification (Aim 1.2). Aim 2: Elucidate the molecular mechanisms underlying how METTL14 protects liver from AATD-induced toxicity. We will determine how the METTL14-CHOP axis regulates AAT deficiency adaptation and liver disease development. (2) We will determine whether m6A modification links METTL14 to CHOP mRNA translation in response to AAT deficiency. Aim 3: Determine the molecular mechanisms underlying how METTL14 is induced by misfolded AAT accumulation through ubiquitin-proteasome pathway. The ubiquitination of METTL14 was dramatically decreased in the liver of the Piz mice without changes in mRNA levels. Here we will explore a novel molecular mechanism that links misfolded AAT accumulation to METTL14 ubiquitination and protein stability.
|Effective start/end date||7/1/21 → 6/30/23|
- Alpha-1 Foundation (Letter - 06-05-2021)
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