Pathogenic SCN2A variants cause early-stage dysfunction in patient-derived neurons

Pathogenic heterozygous variants in SCN2A, which encodes the neuronal sodium channel NaV1.2, cause different types of epilepsy or intellectual disability (ID)/autism without seizures. Previous studies using mouse models or heterologous systems suggest that NaV1.2 channel gain-of-function typically causes epilepsy, whereas loss-of-function leads to ID/autism. How altered channel biophysics translate into patient neurons remains unknown. Here, we investigated iPSC-derived early-stage cortical neurons from ID patients harboring diverse pathogenic SCN2A variants [p.(Leu611Valfs*35); p.(Arg937Cys); p.(Trp1716*)] and compared them with neurons from an epileptic encephalopathy (EE) patient [p.(Glu1803Gly)] and controls. ID neurons consistently expressed lower NaV1.2 protein levels. In neurons with the frameshift variant, NaV1.2 mRNA and protein levels were reduced by ~ 50%, suggesting nonsense-mediated decay and haploinsufficiency. In other ID neurons, only protein levels were reduced implying NaV1.2 instability. Electrophysiological analysis revealed decreased sodium current density and impaired action potential (AP) firing in ID neurons, consistent with reduced NaV1.2 levels. In contrast, epilepsy neurons displayed no change in NaV1.2 levels or sodium current density, but impaired sodium channel inactivation. Single-cell transcriptomics identified dysregulation of distinct molecular pathways including inhibition of oxidative phosphorylation in neurons with SCN2A haploinsufficiency and activation of calcium signaling and neurotransmission in epilepsy neurons. Together, our patient iPSC-derived neurons reveal characteristic sodium channel dysfunction consistent with biophysical changes previously observed in heterologous systems. Additionally, our model links the channel dysfunction in ID to reduced NaV1.2 levels and uncovers impaired AP firing in early-stage neurons. The altered molecular pathways may reflect a homeostatic response to NaV1.2 dysfunction and can guide further investigations.

Rich forests, rich people? Sustainable finance and its links to forests

Investment products labelled as sustainable, as well as regulations on sustainable finance, such as the EU taxonomy for sustainable activities, are on the rise globally. While some of these products and regulations include forests and forestry, the forest-sustainable finance nexus is largely unexplored in academic research. This paper systematically analyses the emerging expert debate spanning across the financial and forest sectors. We conducted 51 in-depth qualitative interviews with experts from financial institutions, timberland and impact investors, international organizations, civil society organizations and academia. We chose mainly experts from Europe, as one of the regions spearheading the topic globally. Based on these, we identify five main narratives on the nexus between sustainable finance and forests. These narratives are strikingly different regarding such dimensions as emphasis on risks versus opportunities, preference for public versus private governance and investments, as well as on the sustainability of forest-related investments per se. While financial sector experts are mainly concerned about financial risks, and only partially about deforestation risks, forest sector experts with financial expertise promote investment opportunities either for the asset class, or to increase private investment in tropical forests. In contrast, some experts from both the forest and financial sectors explicitly exclude forests as investable assets for the private sector, seeing them instead as pure public goods. We conclude with underlining the importance of more cross-sectoral dialogue, but also research, to both critically assess and advance the role of sustainable finance policy and practice in supporting forest conservation, restoration, and sustainable management.