Biology subjects

Kang, H. C.

Publications and source records attributed to Kang, H. C..

4 recordsLinked to original sources

bioRxiv2023

Histone H1.2 Dependent Translocation of Poly (ADP-ribose) Initiates Parthanatos

Toxic cellular insults activate the nuclear protein poly (ADP-ribose) (PAR) polymerase-1 (PARP-1) to initiate parthanatos, a regulated cell death program. PAR acts as a death signal by translocating from the nucleus to the cytosol, where it activates the next steps in the parthanatic cell death cascade. How PAR translocates from the nucleus to the cytosol is not known. Here we show that PARylation and PAR binding to histone H1.2 enables it to act as a carrier, transporting PAR out of the nucleus to the cytosol. Knocking down the expression of histone H1.2 via CRISPR/Cas9 and knockout of histone H1.2 reduces the translocation of PAR to the cytosol after treatment of human cortical neurons with N-methyl-D-aspartate (NMDA) or following oxygen-glucose deprivation (OGD). The PAR-dependent E3 ubiquitin ligase, Iduna (RNF146) ubiquitinates PARylated H1.2. Overexpression of Iduna reduces the expression levels of cytosolic histone H1.2, preventing the translocation of PAR following NMDA or OGD exposure, similar to inhibition of PAR formation by the PARP inhibitor, DPQ. Whereas, the catalytically null variant Iduna C60A, or the PAR binding mutant Iduna Y156A and R157A (YRAA) was ineffective in ubiquitinating histone H1.2 and preventing the reduction in cytosolic histone H1.2 levels and PAR translocation from the nucleus to the cytosol. Histone H1.2 heterozygote and homozygote knockout mice exhibited reduced infarct volume 24 hrs post middle cerebral artery occlusion (MCAO) and showed better recovery in motor deficits than wildtype littermates at day 3 and/or day 7 post MCAO. Collectively, these findings reveal histone H1.2 as the key carrier of PAR out of the nucleus to the cytosol where it participates in the next step of the parthanatic cell death cascade.

cell biology↗

bioRxiv2023

MARCH5-dependent NLRP3 ubiquitination is an essential step for NEK7 docking on the mitochondria

The NLRP3 inflammasome is a global immune-sensor that is activated by a repertoire of endogenous and exogenous stimuli. NLRP3 translocates to mitochondria but whether mitochondria involvement in the inflammasome assembly is unclear. Here, we show that the mitochondrial E3 ligase MARCH5 is a key regulator of NLRP3 inflammasome assembly. Myeloid cell-specific March5 conditional knockout (March5 cKO) mice exhibited an attenuated mortality rate upon LPS or Pseudomonas aeruginosa challenge. Macrophages derived from March5 cKO mice failed to secrete IL-1{beta} and IL-18 after microbial infection. Mechanistically, MARCH5 interacts with the NACHT domain of NLRP3 and promotes K27-linked polyubiquitination of K324 and K430 residues of NLRP3. Ubiquitination-defective NLRP3 mutants neither bind to NEK7, nor form NLRP3 oligomers, but remain binding to MAVS. Accordingly, NLRP3 mutants led to abortive ASC speck formation and diminished IL-1{beta} production. We propose that MARCH5-dependent NLRP3 ubiquitination creates a docking site for NEK7 binding, playing as a fundamental step-wise regulator on the mitochondria.

immunology↗

bioRxiv2022

Proteome-wide microarray-based screening of PAR-binding proteins

Poly(ADP-ribose) (PAR) plays a crucial role in intracellular signaling and scaffolding through covalent modification or non-covalent binding to target proteins. The non- covalent binding PARylome has not been extensively characterized. Here we performed a PAR-binding screen using a human protein microarray that covers most of the human proteome to characterize the non-covalent binding PARylome. A total of 356 PAR- binding proteins were identified. The PAR-binding PARylome suggests that PAR- binding regulates a variety of biological processes beyond well-characterized DNA damage signaling and DNA repair. Proteins that may be reprogrammed by PAR-binding include signaling molecules, transcription factors, nucleic acid binding proteins, calcium binding proteins, ligases, oxidoreductases, enzymes, transferases, hydrolases, and receptors. The global database of PAR-binding proteins that we established will be a valuable tool for further in-depth analysis of the role of PARylation in a wide range of biological contexts.

biochemistry↗

bioRxiv2021

Oncomodulin derived from regeneration-associated macrophages in dorsal root ganglia promotes axon regeneration in the spinal cord

Preconditioning nerve injury drives pro-regenerative perineuronal macrophage activation in dorsal root ganglia (DRG). The present study reports that oncomodulin (ONCM) is produced from the regeneration-associated macrophages (RAMs) and strongly influences regeneration of DRG sensory axons. Preconditioning injury upregulated ONCM in DRG macrophages in a CCR2 dependent manner. ONCM in macrophages was necessary to produce RAMs in the in vitro model of neuron-macrophage interaction and played an essential role in for preconditioning or CCL2-induced neurite outgrowth. ONCM potently increased neurite outgrowth in cultured DRG neurons by activating a distinct gene set, particularly neuropeptide-related genes. Increasing extracellularly secreted ONCM in DRGs sufficiently enhanced capacity of neurite outgrowth. To achieve sustained ONCM activity in vivo, recombinant ONCM was encapsulated by a reducible epsilon-poly(L-lysine)-nanogel (REPL-NG) system based on electrostatic interaction. Localized injection of REPL-NG/ONCM complex into DRGs achieved a remarkable long-range axonal regeneration beyond spinal cord lesion, surpassing the extent of the preconditioning effects.

neuroscience↗