Niksic, A. | Search bioRxiv

bioRxiv2025

Histone Succinylation-Driven LINE-1 Reactivation Links High-Fat Diet Stress to Hepatic Inflammation and Liver Disease

Endogenous retroelements such as LINE-1 (L1) are stress-responsive genomic elements increasingly implicated in stress induced inflammation and associated pathogenic states. Here, we uncover a novel mechanism whereby high-fat diet-associated palmitic acid stress triggers chromatin remodeling that derepresses L1 elements and an IRF3-dependent interferon response, leading to innate immune activation in hepatocytes. Mechanistically, we show that that palmitic acid exposure promoted p300/CBP-mediated H3K122 succinylation at L1 promoters, coupled with reduced sirtuin desuccinylase cofactor availability, thereby enhancing chromatin accessibility and transcription. Antisense oligonucleotide-mediated L1 silencing abrogated this response by resetting chromatin homeostasis, demonstrating a causal role for L1 in palmitate-induced inflammation. In vivo, L1 knockdown in a fructose-palmitate-cholesterol (FPC) diet-induced mouse model of MASLD/MASH improved insulin sensitivity, reduced hepatic inflammation, and ameliorated fibrosis. These findings identify L1 derepression as a key epigenetic and inflammatory effector of dietary lipid stress and establish L1 inhibition as a potential therapeutic strategy for metabolic liver disease.

molecular biology↗

bioRxiv2020

Variation in a pleiotropic regulatory module drives evolution of head shape and eye size in Drosophila

Revealing the mechanisms underlying the breath-taking morphological diversity observed in nature is a major challenge in Biology. It has been established that recurrent mutations in hotspot genes cause the repeated evolution of rather simple morphological traits, such as body pigmentation or the gain and loss of structures. To date, however, it remains elusive whether hotspot genes contribute to natural variation in complex morphological traits, such as the size and shape of organs. Since natural variation in head morphology is pervasive in Drosophila, we studied the molecular and developmental basis of differences in compound eye size and head shape in two closely related Drosophila species. We show that differences in both traits are established late during head development and we applied comparative transcriptomics and chromatin accessibility data to identify the GATA transcription factor Pannier (Pnr) as central factor regulating these differences. Although the genetic manipulation of Pnr affected multiple aspects of dorsal head development, the effect of natural variation is restricted to a subset of the phenotypic space. We present data suggesting that this developmental constraint is caused by the co-evolution of expression of pnr and its co-factor u-shaped (ush). We propose that natural variation in highly connected developmental regulators with pleiotropic functions is a major driver for morphological evolution and we discuss implications on gene regulatory network evolution. In comparison to previous findings, our data strongly suggests that evolutionary hotspots do not contribute to the repeated evolution of eye size and head shape in Drosophila.

evolutionary biology↗