Sopak Supakul

Benign adult familial myoclonus epilepsy (BAFME) is caused by intronic TTTCA and TTTTA repeat expansions in SAMD12 and other genes; the neuronal basis of cortical hyperexcitability, however, remains unclear. We generated induced pluripotent stem cell (iPSC)-derived glutamatergic and GABAergic neurons from three BAFME1 patients and examined functional and transcriptomic phenotypes. Patient-derived neurons retained the pathogenic repeat expansions and showed a tendency toward upstream intronic RNA accumulation. Calcium imaging revealed increased spontaneous Ca2 + transient frequency in both neuronal subtypes, indicating heightened activity. Pharmacological profiling demonstrated attenuated responses to calcium-permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptor (CP-AMPAR) blockade and GABAA receptor antagonism in GABAergic neurons, suggesting altered inhibitory signaling. RNA sequencing revealed transcriptomic alterations without differential expression of ion channels and neurotransmitter receptors. In glutamatergic neurons, ATF4-regulated genes, including SLC7A5 encoding LAT1, a Kv1.2 channel modulator, were downregulated. Reduced SLC7A5 expression was validated at both mRNA and protein levels. In GABAergic neurons, synapse-associated genes PTPRD and GPC6 were upregulated. TCERG1L and NLRP2 were suppressed across both neuronal subtypes. These findings suggest subtype-specific alterations may contribute to neuronal hyperexcitability in BAFME and provide a platform for mechanistic studies of repeat expansion-associated epilepsies.

ABSTRACT Several protocols for generating oligodendrocytes (OLs) from human pluripotent stem cells have been reported. However, they are limited by long culture duration, intensive handling, and low yield of mature OLs. Transcription factor‐based strategies have improved efficiency, but OLIG2 and SOX10, key regulators of oligodendrocyte precursor cells (OPCs), also promote alternative neural fates. Here, we developed a Tet‐inducible system to control SOX10 and OLIG2 expression, including that of a phosphorylation‐deficient OLIG2 mutant (S147A). Co‐expression of SOX10 and OLIG2 enhanced OPC induction, confirmed by O4 positivity and transcriptomic profiling. Interestingly, only a brief induction of SOX10 + OLIG2(S147A) (2–5 days) efficiently yielded myelin basic protein positive OLs within 25 days, reaching approximately 20% of total cells. In contrast, sustained doxycycline‐mediated expression of SOX10 and OLIG2(S147A) favored OPC proliferation and delayed OL maturation. These findings highlight the importance of temporal control of transcription factor activity in accelerating OL differentiation and provide a practical platform for disease modeling and regenerative applications.

Amyotrophic Lateral Sclerosis/Parkinsonism-Dementia Complex (ALS/PDC), a rare and complex neurological disorder, is predominantly observed in the Western Pacific islands, including regions of Japan, Guam, and Papua. This enigmatic condition continues to capture medical attention due to affected patients displaying symptoms that parallel those seen in either classical amyotrophic lateral sclerosis (ALS) or Parkinson's disease (PD). Distinctly, postmortem examinations of the brains of affected individuals have shown the presence of α-synuclein aggregates and TDP-43, which are hallmarks of PD and classical ALS, respectively. These observations are further complicated by the detection of phosphorylated tau, accentuating the multifaceted proteinopathic nature of ALS/PDC. The etiological foundations of this disease remain undetermined, and genetic investigations have yet to provide conclusive answers. However, emerging evidence has implicated the contribution of astrocytes, pivotal cells for maintaining brain health, to neurodegenerative onset, and likely to play a significant role in the pathogenesis of ALS/PDC. Leveraging advanced induced pluripotent stem cell technology, our team cultivated multiple astrocyte lines to further investigate the Japanese variant of ALS/PDC (Kii ALS/PDC). CHCHD2 emerged as a significantly dysregulated gene when disease astrocytes were compared to healthy controls. Our analyses also revealed imbalances in the activation of specific pathways: those associated with astrocytic cilium dysfunction, known to be involved in neurodegeneration, and those related to major neurological disorders, including classical ALS and PD. Further in-depth examinations revealed abnormalities in the mitochondrial morphology and metabolic processes of the affected astrocytes. A particularly striking observation was the reduced expression of CHCHD2 in the spinal cord, motor cortex, and oculomotor nuclei of patients with Kii ALS/PDC. In summary, our findings suggest a potential reduction in the support Kii ALS/PDC astrocytes provide to neurons, emphasizing the need to explore the role of CHCHD2 in maintaining mitochondrial health and its implications for the disease.