ELIZABETH M PERRUCCIO
$593,803
OHIO STATE UNIVERSITY
Ohio
National Institute on Alcohol Abuse and Alcoholism (NIAAA)
Long-term excessive alcohol consumption leads to a significant prevalence of alcoholic cardiomyopathy (ACM) that is characterized by impaired cardiac function (heart failure, HF) in the absence of other cardiovascular diseases. During the COVID-19 pandemic, increased alcohol consumption due to social isolation has magnified the serious problem. Clinically, ACM is a leading cause of non-ischemic dilated cardiomyopathy increasing mortality and morbidity and puts a tremendous economic burden on our healthcare system. Sarcoplasmic reticulum (SR) Ca2+ ([Ca2+]SR) mishandling is known to play a key role in cardiac hypertrophy and HF development. The SR Ca2+ pump, SERCA2, is essential in [Ca2+]SR handling and reduced SERCA2 expression leading to depleted [Ca2+]SR load is a hallmark of HF. However, failed clinical trials of SERCA2 gene therapy in HF patients suggests that increasing the abundance of SERCA2 per se is insufficient to reverse HF. Although alcohol abuse is a significant risk factor for HF, it can take many years for an alcoholic individual undergoing adaptive cardiac changes with normal function to reach the point of ACM. The underlying mechanisms remain unclear to date. The goal of this proposal is to fill this knowledge gap by exploring a previously unknown mechanism of alcohol activated JNK2 acting as a driver of ACM onset. Our pilot findings show that JNK2, but not JNK1, is critical in alcohol-caused cardiac remodeling via a dynamic regulation of JNK2α variants in augmented SERCA2 pump activity (adaptive) followed by suppressed SERCA2 transcriptional activity (maladaptive). Our lab recently reported a critical role of JNK2 (not JNK1) in enhanced [Ca2+]SR uptake/load via enhanced SERCA2 activity. Aim 1 here will detail how JNK2 interacts/phosphorylates SERCA2 to augment its pump activity as an adaptive response to long-term alcohol exposure. JNK2 has multiple splicing variants (i.e. α, β). We identified that α1, α2, β2 (but not β1) are predominantly expressed in the human heart. And we found significantly increased JNK2α2, but reduced JNK2α1 correlated with reduced SERCA2 expression in human ACM LVs, while increased JNK2α2 suppressed the SERCA2 promoter activity, which is likely due to hypermethylated SERCA2 promoter through JNK2α2-upregulated DNA methyltransferase DNMT1 transcription activity. Thus, Aim 2 will define how JNK2α2 suppresses SERCA2 expression and onsets ACM, and test the translational potentials of blocking the JNK2α2 actions as an anti-ACM therapeutic strategy. Our multi-discipline team will use a unique combination of cutting-edge approaches (protein-SR-myocyte-heart-animal, in vitro to ex vivo to in vivo) including a novel battery of cardiac-specific JNK2α2 mouse models (JNK2act, MKK7D, MKK7D-JNK2dn, JNK2dn), in vivo gene transfer, and biochemical/proteomic/CUT&Tag-Seq/bioinformatics analyses to systematically fulfill the two Specific Aims. The scientific premise of this innovative proposal is strong given the integration of targeted functional measurements and paired with mechanistic experimental designs along with appropriate alternative approaches. Anticipated outcomes from the mechanistic and proof-of-concept translational studies will reveal causal role of JNK2α in ACM onset and provide translational insight into modulating JNK2α variants as a prospective anti-HF intervention.