Elizabeth M. McNally

Current obesity therapies reduce weight but often fail to preserve lean mass or sustain metabolic benefit. Glucagon-like peptide-1 receptor agonists (GLP-1RA) improve obesity-associated metabolic disease, but weight loss is often accompanied by reduced energy expenditure, loss of lean mass, and rapid fat-predominant regain after treatment discontinuation. We hypothesized that pharmacologic activation of adipose thermogenesis could specifically target fat loss, complement appetite suppression by increasing energy expenditure, and improve the metabolic quality of weight loss. Guided by our finding that diet-induced thermogenesis is mediated by a zinc finger protein 423 (ZFP423)-controlled pathway, we developed adipose-directed antisense oligonucleotides (ASOs) targeting ZFP423, a transcriptional repressor of brown and beige adipocyte identity. In lean and diet-induced obese mice, weekly Zfp423 ASO treatment induced white adipose beiging, increased body temperature and oxygen consumption, and improved glucose homeostasis, insulin sensitivity, lipid metabolism, mitochondrial respiration, and hepatic steatosis. When combined with the GLP1-RA semaglutide, Zfp423 ASO produced greater weight and fat loss than either monotherapy while preserving lean mass and improving metabolic outcomes. These findings identify Zfp423 as an RNA therapeutic target and support adipose thermogenesis as a complementary strategy for metabolically healthier obesity treatment.

Calcium calmodulin kinase II (CaMKII) signaling is activated by muscle use and drives gene expression that promotes slow oxidative muscle phenotype. Previously, we showed that the calpain 3 knockout (C3KO) mouse model of limb girdle muscular dystrophy R1 (LGMDR1) exhibits impaired slow-oxidative gene expression and these deficits were associated with reduced levels of the CaMKIIβ isoform and attenuated CaMKII signaling in C3KO muscles. To investigate the contribution of CaMKIIβ signaling to the calpain 3-deficient phenotype, we generated both loss-of-function (muscle-specific conditional knockout, Camk2b cKO) and gain-of-function (muscle-specific overexpression of a constitutively active CaMK2b) models. Camk2b cKO muscles exhibited myopathic features and weakness and their muscles failed to upregulate genes that promote oxidative metabolism and stress-responses following endurance exercise, similarly to C3KO muscles. Mitochondrial respiration showed reduced activity of complex I, complex II and fatty acid oxidation. RNA sequencing of LGMDR1 patient biopsies revealed a similar reduction in genes involved in oxidative metabolism, aligning human and mouse findings. Overexpression of a constitutively active Camk2b in C3KO muscles enhanced oxidative metabolism and improved functional performance. Our results support the hypothesis that blunted CaMKIIβ signaling contributes to the failed upregulation of genes involved in oxidative metabolism and stress-responses in C3KO muscles. These studies highlight metabolic insufficiency as a central contributor to LGMDR1 pathogenesis and support the therapeutic potential of targeting CaMKII signaling to ameliorate disease features in LGMDR1.

Genetic testing for cardiomyopathy and arrhythmia (CM/ARRH) provides diagnostic information and informs screening for at-risk relatives. Clinical guidelines recommend genetic testing for these conditions; however, data on how genetic test results influence clinical management recommendations are limited. Here, we determined the frequency of cardiologist-recommended management changes for patients following CM/ARRH genetic testing. This was a retrospective cross-sectional study of patients referred for multigene panel testing between April 2016 and April 2024. Genetically-experienced cardiologists at multicenter academic clinical practices were recruited for participation to complete surveys indicating clinical decision making on patients who had genetic testing. Cases for review were randomly selected to have both positive and non-positive results. Among 249 patients (138 positive, 111 non-positive), 136 (54.6%) received clinical management recommendations for their own or their at-risk relatives? care. Of these, 75 (55.1%) received recommendations for the patient?s own care, most frequently additional diagnostic tests/procedures (n=33). Compared to non-positive results, patients with positive results were more likely to receive recommendations for their own management (66/138, 47.8% vs 9/111, 8.1%; P<0.00001). Patients with positive results in arrhythmogenic cardiomyopathy genes had 263% higher odds of recommended management changes compared to those with TTN (OR=3.63, CI:1.40-9.84, P=0.009). The results from CM/ARRH genetic testing on affected patients influenced cardiologists? medical decision making and management recommendations. Additional research is needed to evaluate how genetic testing for CM/ARRH impact health outcomes.

BACKGROUND: Cardiomyopathies frequently arise from rare, highly penetrant coding variants with variable clinical expressivity. Genome-wide association studies (GWAS) suggest significant polygenic contributions to cardiovascular diseases, including cardiomyopathy. Most GWAS loci map to poorly conserved noncoding regions, requiring human genome context for experimental validation. METHODS: We created engineered heart tissues (EHTs) from human induced pluripotent stem cell-derived cardiomyocytes and primary cardiac fibroblasts. We assayed single-cell gene expression and chromatin accessibility to generate comprehensive genome-wide regulatory maps. Open chromatin regions were integrated with chromatin contact information and used to fine-map cardiomyopathy GWAS single-nucleotide polymorphisms. Single-nucleotide polymorphisms and their associated open chromatin regions were assessed using reporter assays, genome editing, and expression profiling. RESULTS: EHT Single-cell RNA-seq recapitulated major cardiac cell types, with advanced cardiomyocyte maturation compared with monolayer human induced pluripotent stem cell cardiomyocytes. More than 400 000 open chromatin regions were resolved to cell types and assayed for transcription factor motifs. Functional fine-mapping of GWAS loci prioritized 5817 variants, and reporter assays validated allele-specific enhancer activity. We identified an intergenic chr3p25.1 locus harboring significant GWAS signals from both dilated cardiomyopathy and left ventricular ejection fraction. Several of these variants lie in open chromatin regions participating in long-range chromatin interactions with SLC6A6 and GRIP2 . Haplotype-resolved and synthetic reporter assays confirmed enhancer activity and narrowed candidate single-nucleotide polymorphisms. CRISPR-deletion of this region reduced expression of both SLC6A6 and GRIP2 , indicating the enhancer regulates the expression of multiple genes. EHTs with the enhancer deletion displayed markedly reduced contractile function, confirming that this enhancer region contributes to myocardial function. CONCLUSIONS: EHTs are an experimentally tractable platform for testing the function of noncoding variants as modifiers of cardiomyopathy. Variants fine-mapped from cardiomyopathies using EHT regulatory maps have functional consequences and provide a set of prioritized sites to advance the study of polygenic heart failure.

Plasma membrane repair is critical for tissue integrity, especially for elongated contractile muscle cells. Genetically mediated defects in plasma membrane resealing produce persistent leak, leading to a disordered extracellular matrix (ECM). Loss of the membrane repair protein dysferlin slows sarcolemmal resealing and promotes excess leak. Annexin A6 is also implicated in sarcolemmal repair, forming repair caps at the site of membrane disruption. On its own, deletion of the gene for annexin A6, Anxa6 , had little effect on muscle health. In contrast, combined loss of dysferlin and annexin A6 ( DysfA6 ) generated muscle fibers with profoundly defective membrane leak. Strikingly, Anxa6 deletion in the context of loss of dystrophin ( mdxA6 ) did not exacerbate muscle defects. The persistent membrane leak in DysfA6 muscle resulted in marked macrophage infiltration with disordered macrophage polarization. Injured muscle fibers were targets of macrophage efferocytosis. Loss of Anxa6 was associated with increased expression of annexins A1 and A2, both of which were heavily deposited into the ECM. In vitro, macrophages exposed to annexins A1 and A2 increased Csf1 expression, consistent with a model where excess leak results in annexins A1 and A2 in the ECM, where this protein composition influences macrophage proliferation and efferocytosis. Muscle lacking dysferlin and annexin A6, two proteins critical for muscle resealing, cause leaky membranges and invite macrophages to come take a bite.

Continuous biomarker monitoring is revolutionizing chronic disease management, with glucose monitoring for diabetes as the primary example. Given the success of this approach, a transition to continuous protein monitoring (CPM, a real-time, implantable or wearable technology) could similarly advance precision medicine. In this work, we review state-of-the-art CPM platforms and their prospective clinical impact across both chronic disorders—metabolic, cardiovascular, autoimmune, and neurodegenerative—and acute crises, such as sepsis and transplant dysfunction. We also highlight remaining barriers to widespread adoption, including sensor stability, robust machine learning models for live interpretation, and responsible data handling for patient privacy. With continued engineering and clinical validation, emerging biosensor technologies could transform disease management, facilitating earlier interventions and individualizing treatment strategies, ultimately improving patient outcomes.