Frontotemporal dementia is a debilitating neurodegenerative disorder characterized by frontal and temporal lobe degeneration, resulting in behavioral changes, language difficulties, and cognitive decline. In this study, smallRNA sequencing was conducted on postmortem brain tissues obtained from the frontal and temporal of FTD patients with GRN, MAPT, or C9ORF72 mutations. Our analysis identified miR-129-5p as consistently deregulated across all analyzed mutation conditions and brain regions. Functional investigations in in-vitro models revealed a novel role of miR-129-5p in astrocytes, where its loss led to neuroinflammation and impaired neuronal support functions, including reduced glutamate uptake. Depletion of miR-129-5p in astrocytes also resulted in the loss of neuronal spines and altered neuronal network activity in a cell culture system. These findings highlight miR-129-5p as a potential therapeutic target in neurodegenerative diseases and also sheds light on the role of astrocytes in Frontotemporal dementia pathogenesis.

Aging leads to cognitive decline and increased risk of neurodegenerative diseases. While molecular changes in central nervous system (CNS) cells contribute to this decline, the mechanisms are not fully understood. Long non-coding RNAs (lncRNAs) are key regulators of cellular functions. Background/Objectives: The roles of lncRNAs in aging, especially in glial cells, are not well characterized. Methods: We investigated lncRNA expression in non-neuronal cells from aged mice and identified 3222401L13Rik, a previously unstudied lncRNA, as upregulated in astrocytes during aging. Results: Knockdown of 3222401L13Rik in primary astrocytes revealed its critical role in regulating genes for neuronal support and synapse organization, a function conserved in human iPSC-derived astrocytes. A 3222401L13Rik interacts with the transcription factor Neuronal PAS Domain Protein 3 (Npas3), and overexpression of Npas3 rescues deficits in astrocytes lacking 3222401L13Rik. Conclusions: These data suggest that 3222401L13Rik upregulation may help delay age-related cognitive decline.

Organic cation transporters (OCTs) can transport structurally highly diverse substrates. The molecular basis of this extensive polyspecificity has been further elucidated by cryo-EM. Apparently, in addition to negatively charged amino acids, aromatic residues may contribute to substrate binding and substrate selectivity. In this study, we provide a comprehensive characterization of phenylalanine 244 in OCT1 function. We analyzed the uptake of 144 OCT1 substrates for the phenylalanine 244 to alanine substitution compared to WTOCT1. This substitution had highly substrate-specific effects ranging from transport reduced to 10% of WT activity up to 8-fold increased transport rates. Four percent of substrates showed strongly increased uptake (>200% of WT) whereas 39% showed strongly reduced transport (<50% of WT). Particularly with larger, more hydrophobic, and more aromatic substrates, the Phe244Ala substitution resulted in higher transport rates and lower inhibition of the transporter. In contrast, substrates with a lower molecular weight and less aromatic rings showed generally decreased uptake rates. A comparison of our data to available transport kinetic data demonstrates that generally, high-affinity low-capacity substrates show increased uptake by the Phe244Ala substitution, whereas low-affinity high-capacity substrates are characterized by reduced transport rates. Altogether, our study provides the first comprehensive characterization of the functional role of an aromatic amino acid within the substrate translocation pathway of OCT1. The pleiotropic function further highlights that phenylalanine 244 interacts in a highly specific manner with OCT1 substrates and inhibitors.

Long non-coding RNAs (lncRNAs) are increasingly recognized as regulators of cellular identity and disease associated gene expression programs, yet their role in astrocyte reactivity remains poorly understood. Here, we profiled lncRNA expression in primary mouse astrocytes exposed to inflammatory activation paradigms that model microglia driven signaling. This identified a conserved set of activation responsive lncRNAs, among which Gm16685 emerged as one of the most strongly induced candidates. Gm16685 and its human homolog MITA1 were enriched in the nucleus, and MITA1 expression was increased in selected human datasets from Alzheimer’s disease, Parkinson’s disease and frontotemporal dementia patients. Functional depletion of Gm16685 attenuated inflammatory gene expression and several activation associated astrocyte phenotypes, including reactive oxygen species production, glutamate handling, phagocytic activity and proliferation. Time-resolved transcriptomic analysis indicated that Gm16685 is required for the timely induction of inflammatory response genes. Mechanistically, Gm16685 / MITA1 interacted with the RNA binding protein PCBP2, and Gm16685 depletion was associated with reduced PCBP2 protein abundance, altered splicing of Inhibitor of NF-κB Kinase Subunit Beta (IKKβ) and a shift in downstream inflammatory signaling. Together, our findings identify Gm16685 / MITA1 as a conserved lncRNA regulator of astrocyte reactivity and suggest that non-coding RNA dependent control of RNA binding proteins contributes to inflammatory signaling in neurodegenerative disease relevant contexts.