Venegas, A. | bioRxiv Science

bioRxiv2023

Activity-assembled nBAF complex mediates rapid immediate early gene transcription by regulating RNA Polymerase II productive elongation.

Signal-dependent RNA Polymerase II (Pol2) productive elongation is an integral component of gene transcription, including those of immediate early genes (IEGs) induced by neuronal activity. However, it remains unclear how productively elongating Pol2 overcome nucleosomal barriers. Using RNAi, three degraders, and several small molecule inhibitors, we show that the mammalian SWI/SNF complex of neurons (neuronal BAF, or nBAF) is required for activity-induced transcription of neuronal IEGs, including Arc. The nBAF complex facilitates promoter-proximal Pol2 pausing, signal-dependent Pol2 recruitment (loading), and importantly, mediates productive elongation in the gene body via interaction with the elongation complex and elongation-competent Pol2. Mechanistically, Pol2 elongation is mediated by activity-induced nBAF assembly (especially, ARID1A recruitment) and its ATPase activity. Together, our data demonstrate that the nBAF complex regulates several aspects of Pol2 transcription and reveal mechanisms underlying activity-induced Pol2 elongation. These findings may offer insights into human maladies etiologically associated with mutational interdiction of BAF functions.

neuroscience↗

bioRxiv2020

p38delta genetic ablation protects female mice from anthracycline cardiotoxicity

BACKGROUNDThe efficacy of an anthracycline antibiotic doxorubicin (DOX) as a chemotherapeutic agent is limited by dose-dependent cardiotoxicity. DOX is associated with activation of intracellular stress signaling pathways including p38 MAPKs. While previous studies have implicated p38 MAPK signaling in DOX-induced cardiac injury, the roles of the individual p38 isoforms, specifically, of the alternative isoforms p38{gamma} and p38{delta}, remain uncharacterized. OBJECTIVESTo determine the potential cardioprotective effects of p38{gamma} and p38{delta} genetic deletion in mice subjected to acute DOX treatment. METHODSMale and female wild-type (WT), p38{gamma}-/-, p38{delta}-/- and p38{gamma}-/-{delta}-/- mice were injected with 30 mg/kg DOX and their survival was tracked for ten days. During this period cardiac function was assessed by echocardiography and electrocardiography and fibrosis by PicroSirius Red staining. Immunoblotting was performed to assess the expression of signaling proteins and markers linked to autophagy. RESULTSSignificantly improved survival was observed in p38{delta}-/- female mice post-DOX relative to WT females, but not in p38{gamma}-/- or p38{gamma}-/-{delta}-/- male or female mice. The improved survival in DOX-treated p38{delta}-/- females was associated with decreased fibrosis, increased cardiac output and LV diameter relative to DOX-treated WT females, and similar to saline-treated controls. Structural and echocardiographic parameters were either unchanged or worsened in all other groups. Increased autophagy, as evidenced by increased LC3-II level, and decreased mTOR activation was also observed in DOX-treated p38{delta}-/- females. CONCLUSIONSp38{delta} plays a crucial role in promoting DOX-induced cardiotoxicity in female mice by inhibiting autophagy. Therefore, p38{delta} targeting could be a potential cardioprotective strategy in anthracycline chemotherapy. NEW AND NOTEWORTHYThis study for the first time identifies the roles of the alternative p38{gamma} and p38{delta} MAPK isoforms in promoting DOX-cardiotoxicity in a sex-specific manner. While p38{gamma} systemic deletion did not affect DOX-cardiotoxicity, p38{delta} systemic deletion was cardioprotective in female but not in male mice. Cardiac structure and function were preserved in DOX-treated p38{delta}-/- females and autophagy was increased.

physiology↗