Baudry, M. | bioRxiv Science

bioRxiv2025

Calpain-2 inhibition or deletion enhances levels of the transcription Factor, MEIS2, and stimulates neurogenesis

Neurogenesis takes place in the subventricular zone (SVZ) and in the dentate gyrus (DG) of the hippocampus of many adult mammalian species. Recent findings indicate that calpain-2 could participate in neurogenesis regulation through the truncation of the transcription factor, Myeloid Ecotropic Viral Integration Site 2 (MEIS2). The present study aimed to test the effects of calpain-2 inhibition/deletion on MEIS2 levels and neurogenesis in adult mice. Two-to-three month-old mice were injected with a selective calpain-2 inhibitor, NA-184, and sacrificed 24 h later. In addition, two-to-three month-old conditional calpain-2 knock-out (C2KO) and calpain-1 knock-out (C1KO) mice were used. Levels of MEIS2 and of cell markers for neurogenesis were analyzed using immunohistochemistry and western blots. Dendritic spines in hippocampal neurons were also analyzed by Golgi staining. Acute treatment of wild-type (WT) mice with NA-184 increased levels of MEIS2 in various brain structures. It also increased numbers of neurons immunopositive for Ki67 and DCX, two markers for neurogenesis, in both the SVZ and DG. MEIS2 levels were elevated in C2KO mouse brain, while they were decreased in C1KO mouse brain. Compared to those in WT mice, neurons from C2KO mice exhibited a decrease in the number of filipodia spines and an increase in the number of mushroom spines, while those from C1KO exhibited opposite changes. These findings further emphasize the critical and opposite roles of calpain-1 and calpain-2 in brain functions in general, and in neurogenesis in particular with MEIS2 as a major downstream mediator. These findings also underline previous conclusions that calpain-1 promotes spine maturation and synaptic plasticity while calpain-2 hinders spine maturation and synaptic plasticity. These results indicate that calpain-2 inhibition/deletion results in increased neurogenesis, as well as in increased maturation of dendritic spines, potentially due to increased levels and activation of MEIS2. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=139 SRC="FIGDIR/small/677817v1_ufig1.gif" ALT="Figure 1"> View larger version (16K): org.highwire.dtl.DTLVardef@1277e38org.highwire.dtl.DTLVardef@1cfa4aaorg.highwire.dtl.DTLVardef@143ac65org.highwire.dtl.DTLVardef@1eb28de_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2023

Identification and neuroprotective properties of NA-184, a selective calpain-2 inhibitor

Our laboratory has shown that calpain-2 activation in the brain following acute injury is directly related to neuronal damage and the long-term functional consequences of the injury, while calpain-1 activation is generally neuroprotective and calpain-1 deletion exacerbates neuronal injury. We have also shown that a relatively selective calpain-2 inhibitor, referred to as C2I, enhanced long-term potentiation and learning and memory, and provided neuroprotection in the controlled cortical impact (CCI) model of traumatic brain injury (TBI) in mice. Similar results were also obtained in conditional calpain-2 knock-out mice. Using molecular dynamic simulation and Site Identification by Ligand Competitive Saturation (SILCS) software, we report here the discovery of a selective calpain-2 inhibitor NA-184, (S)-2-(3-benzylureido)-N-((R,S)-1-((3-chloro-2-methoxybenzyl)amino)-1,2-dioxopentan-3-yl)-4-methylpentanamide whose properties make it a good clinical candidate for the treatment of TBI.

neuroscience↗

bioRxiv2018

UBE3A-mediated p18/LAMTOR1 ubiquitination and degradation regulate mTORC1 activity and synaptic plasticity

Accumulating evidence indicates that the lysosomal Ragulator complex is essential for full activation of the mechanistic target of rapamycin complex 1 (mTORC1). Abnormal mTORC1 activation has been implicated in several developmental neurological disorders, including Angelman syndrome (AS), which is caused by maternal deficiency of the ubiquitin E3 ligase UBE3A. Here we report that Ube3a regulates mTORC1 signaling by targeting p18, a subunit of the Ragulator. Ube3a ubiquinates p18, resulting in its proteasomal degradation, and Ube3a deficiency in hippocampus of AS mice results in increased lysosomal localization of p18 and other members of the Ragulator-Rag complex, such as RagA, and increased mTORC1 activity. P18 down-regulation by siRNA or shRNA in hippocampal CA1 neurons of AS mice reduces elevated mTORC1 activity and improves long-term potentiation (LTP) and dendritic spine maturation. Our results indicate that Ube3a-mediated regulation of p18 and subsequent mTORC1 signaling is critical for typical synaptic plasticity and dendritic spine development.

neuroscience↗