Hannafon, B. | bioRxiv Science

bioRxiv2025

A Non-canonical Role for Hepatocyte MLKL in Promoting Mitochondrial Dysfunction and Senescence in the Aging Liver

Liver aging is characterized by chronic inflammation and metabolic dysfunction that contributes to the progression of metabolic dysfunction-associated steatotic liver disease (MASLD). Necroptosis, a form of inflammatory cell death, is activated in aging livers, and genetic (Ripk3-/-or Mlkl-/- mice) or pharmacological (RIPK1 inhibitor necrostatin-1s) inhibition of necroptosis attenuates liver inflammation and pathology. However, the cell type-specific role of necroptosis in liver aging remains unclear. Given that MLKL is expressed in hepatocytes, and its expression increases with age, we generated hepatocyte-specific MLKL-overexpressing mice (MLKLHepOE) to determine its role in liver aging. Unexpectedly, MLKL overexpression in hepatocytes did not induce necroptosis, but instead upregulated markers of cellular senescence (cell cycle arrest genes and SASP factors), increased macrophage infiltration, and elevated M1 macrophage marker expression. Electron microscopy and mitochondrial analyses revealed abnormal mitochondrial morphology, elevated oxidative stress, and disrupted mitochondrial dynamics, while lipidomics demonstrated alterations in hepatic lipid metabolites. In agreement with our observations in MLKLHepOE mice, MLKL overexpression in AML12 hepatocytes impaired mitochondrial respiration, increased proinflammatory extracellular vesicle (EV) release, and induced senescence markers, without triggering cell death. Together, these findings reveal a non-lethal, non-necroptotic role for MLKL in promoting hepatocyte senescence and metabolic dysfunction via mitochondrial impairment and EV-mediated inflammation. Our study highlights MLKL as a novel driver of liver inflammaging and a potential therapeutic target for age-related liver disease.

cell biology↗

bioRxiv2024

Preferential Release of microRNAs via Extracellular Vesicles is Associated with Ductal Carcinoma In Situ to Invasive Breast Cancer Progression

Ductal carcinoma in situ (DCIS) is a benign "pre-cancer" that increases the risk of invasive breast cancer (IBC). Not all DCIS progress to IBC, and the primary factors driving progression remain unclear. Small extracellular vesicles (sEVs) or exosomes are known to play a role in advanced cancers, but their involvement in DCIS is poorly understood. This study examined the role of sEVs and their RNA content in DCIS progression. Rab27A, which regulates exosome release, is elevated in DCIS and IBC tissues compared with normal breast tissues. Inhibition of sEV release via Rab27A knockdown alters pro-invasive pathways and reduces invasion in a DCIS mouse model. Using the isogenic MCF10 breast cancer progression series, we found a significant increase in microRNAs (miRNAs) in sEVs from normal to malignant states, with the highest number of differentially expressed miRNAs in IBC sEVs compared with DCIS sEVs. In vivo, DCIS invasive progression elevated circulating sEV miRNA levels, which decreased upon Rab27A knockdown. Re-expression of miR-205, preferentially loaded into IBC sEVs, reduced proliferation, invasion, and EMT marker expression in DCIS cells. Combined Rab27A knockdown and miR-205 expression repressed TGF-{beta} signaling, activated p38, and induced cell cycle arrest and cell death. These findings illustrate that sEVs and their miRNAs promote DCIS progression, and the reintroduction of miR-205 in DCIS cells can inhibit invasive progression.

cancer biology↗