Proteomic identification of nuclear rupture-associated proteins in laminopathy hearts

The nuclear envelope can rupture in various age-associated conditions, including cellular senescence, neurodegenerative disorders, cancer, myocardial infarction, and premature aging. Nuclear rupture can lead to pathological consequences, such as gene expression defects, DNA damage, and innate immune activation, or instead be resolved through endogenous repair. How these divergent outcomes are regulated remains unknown. This is a critical gap in our understanding, because uncovering the underlying mechanisms could enable strategies to prevent rupture or promote repair. We hypothesize that proteins recruited to nuclear rupture sites – most of which remain unidentified – regulate these cellular responses. To test this hypothesis, we will systematically identify proteins recruited to nuclear rupture sites. Our disease model is LMNA-related dilated cardiomyopathy (LMNA-DCM), a fatal heart disease. LMNA encodes Lamin A/C, a nuclear lamina protein that maintains nuclear envelope integrity. We have developed cardiomyocyte-specific Lmna-knockout mice (LmnaCKO) as a model of LMNA-DCM and observed frequent nuclear rupture in the heart, as in the patient hearts. In Aim 1, we will identify proteins recruited to nuclear rupture sites in LmnaCKO cardiomyocytes using in-vivo BioID. As baits, we will use three rupture-associated proteins that we found to accumulate at rupture sites in LmnaCKO hearts: namely, BANF1, which binds DNA at rupture sites; LEMD2, a transmembrane protein implicated in membrane repair; and catalytically inactive cGAS (icGAS), which marks both ruptured and repaired nuclei. In Aim 2A, we will validate the localization of candidate proteins identified in Aim 1 and determine whether they preferentially associate with ruptured or repaired nuclei. In Aim 2B, we will assess the functional roles of select candidates by depleting them in vivo and measuring their effects on nuclear rupture and repair frequencies. If successful, this project will yield the first systematic identification of nuclear rupture-associated proteins in any cellular context. By defining the “rupture proteome”, this project has the potential to uncover novel regulators of nuclear rupture and repair, offering the potential therapeutic targets for LMNA-DCM and other age-related conditions characterized by nuclear envelope rupture. Project Number: 1R21AG098113-01A1 | Fiscal Year: 2026 | NIH Institute/Center: National Institute on Aging (NIA) | Principal Investigator: Kohta Ikegami | Institution: CINCINNATI CHILDRENS HOSP MED CTR, CINCINNATI, OH | Award Amount: $445,500 | Activity Code: R21 | Study Section: Cell Structure and Function 1 Study Section[CSF1] View on NIH RePORTER: https://reporter.nih.gov/project-details/11369719