HIPK2 loss promotes TDP-43 cytoplasmic mis-localization through MAPK-pathway and is associated with TDP-43 proteinopathy in vivo

Homeodomain Interacting Protein Kinase 2 (HIPK2) is a stress sensor kinase that has emerged as a key regulator of neuronal homeostasis and survival. In this study, we investigated the role of HIPK2 in neurodegeneration using both in vivo and in vitro models. We show that Hipk2 knockout mice exhibit motor and cognitive deficits reminiscent of those observed in Amyotrophic Lateral Sclerosis (ALS), which are accompanied by cytoplasmic mis-localization of TDP-43, a hallmark of TDP-43 proteinopathies.

Similarly, HIPK2-knockdown (KD) or expression of a kinase-dead mutant in neuronal SH-SY5Y and NSC-34 cells induces TDP-43 cytoplasmic delocalization without altering its expression levels. HIPK2 depletion changes TDP-43 interactome and results in the phosphorylation of TDP-43 RNA recognition motif 1 (RRM1), which is mediated by mitogen-activated protein kinase (MAPK) and known to interfere with TDP-43 binding to RNA. Interestingly, pharmacological inhibition of MAPK reverts the effects of HIPK2 depletion on TDP-43 subcellular localization.

Altogether, these findings identify HIPK2 as a potential regulator of TDP-43 localization, providing new insights into the molecular mechanisms underlying ALS and related neurodegenerative disorders. Moreover, these results suggest that modulation of HIPK2 or its downstream signaling pathways could have important implications for the development of novel therapeutic strategies in TDP-43 proteinopathies. Lucia D’Esposito and Luigi Di Guida for their invaluable support in animal care, and Gennaro Cito for his technical support.

Claudia Crosio (University of Sassari, Italy) for providing stable SH-SY5Y cell line overexpressing human wild-type Myc-TDP-43. This work was supported by NEXTGENERATIONEU (NGEU) and funded by the Ministry of University and Research (MUR), National Recovery and Resilience Plan (NRRP), project MNESYS (PE0000006) - A multiscale integrated approach to the study of the nervous system in health and disease (DN. 1553 11.10.2022) to GP, SP, and GMP; moreover AP’s PhD fellowship is supported by this project. In addition, this work was supported by European Regional Development Fund (POR Campania FESR 2021-2027), project “RARE.Glials”.

Furthermore, this work was supported by the ANR-AAPG2023, project "UnProSec", and by the FRM grant-MND202310017892 to CZ. VV is supported by a Pasteur-Roux-Cantarini postdoctoral fellowship from the Institut Pasteur. These authors contributed equally: Valeria Valente, Andrea Conte.

These authors jointly supervised this work: Simona Paladino, Giovanna Maria Pierantoni. Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy Valeria Valente, Andrea Conte, Alessandra Palazzi, Carolina Canè, Fabio Pucci, Dominga Fasano, Nunzia Mollo, Laura De Rosa, Chiara Zurzolo, Simona Paladino & Giovanna Maria Pierantoni Institut Pasteur, Université Paris Cité, CNRS UMR 3691, Membrane Traffic and Pathogenesis, Paris, France Department of Chemical Sciences, University of Naples Federico II, Naples, Italy Department for the Promotion of Human Sciences and Quality of Life, San Raffaele University, Rome, Italy Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, University of Naples Federico II, Naples, Italy Correspondence to Simona Paladino or Giovanna Maria Pierantoni. The authors declare no competing interests.