Biology subjects

Rodriguez-Nieto, S.

Publications and source records attributed to Rodriguez-Nieto, S..

3 recordsLinked to original sources

bioRxiv2024

C9orf72 repeat expansion-carrying iPSC-microglia from FTD patients show increased phagocytic activity concomitantly with decreased number of autophagosomal-lysosomal vesicles

C9orf72 hexanucleotide repeat expansion (HRE) is a major genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. The role of microglia in these C9orf72 HRE-associated diseases is understudied. To elucidate effects of C9orf72 HRE on microglia, we have characterized human induced pluripotent stem cell-derived microglia (iMG) from behavioral variant frontotemporal dementia (bvFTD) patients carrying the C9orf72 HRE. C9orf72 HRE iMG were compared to iMG from healthy controls and sporadic bvFTD patients. The phenotypes of iMG were analyzed using bulk RNA sequencing, biochemical and immunofluorescence analyses, and live cell imaging. C9orf72 HRE-carrying iMG showed nuclear RNA foci and poly-GP dipeptide repeat proteins but no decreased C9orf72 mRNA or protein expression. TDP-43 pathology was absent from all bvFTD iMG. As compared to healthy control iMG, quantitative immunofluorescence analyses indicated that all bvFTD iMG had reduced number, size, and intensity of LAMP2-A-positive vesicles. C9orf72 HRE-carrying iMG additionally showed decreased number, size, and intensity of p62/SQSTM1-positive vesicles. These changes were accompanied by increased phagocytic activity of the C9orf72 HRE-carrying iMG. Serum starvation increased phagocytic activity also in the iMG of sporadic bvFTD patients. RNA sequencing revealed that iMG of C9orf72 HRE-carrying bvFTD patients as compared to the iMG of sporadic bvFTD patients showed differential gene expression in pathways related to RNA and protein regulation and mitochondrial metabolism. Our data suggest potential alterations in the autophagosomal/lysosomal pathways in bvFTD patient iMG, which are further reinforced by the C9orf72 HRE and functionally manifest as increased phagocytic activity.

neuroscience↗

bioRxiv2024

Single-cell transcriptomic changes in oligodendrocytes and precursors derived from Parkinson's disease patient-iPSCs with LRRK2-G2019S mutation

Despite extensive research, the contribution of the LRRK2 p.G2019S mutation to Parkinsons disease (PD) remains unclear. Recent findings indicate oligodendrocytes (ODCs) and their progenitors are vulnerable in PD pathogenesis. Notably, oligodendrocyte precursor cells (OPCs) exhibit high endogenous expression of LRRK2. We induced PD patient-iPSCs with the LRRK2 p.G2019S mutation into oligodendroglial lineages and performed single-cell RNA sequencing. Cell type composition analysis revealed an increase in OPCs, proliferating OPCs and ciliated ependymal cells in LRRK2 lines, all of which are characterized by LRRK2 expression. Differential expression analysis revealed transcriptomic changes in several pathways, including down-regulation of genes related to myelin assembly in ODCs, semaphorin-plexin pathway in OPCs, and cilium movement in proliferating OPCs. Cell-cell communication analysis identified significant alterations in several signaling pathways including a deactivation of PSAP signaling and an activation of MIF signaling in LRRK2 lines. Additionally, we observed an overall increase in SEMA6 signaling communication in LRRK2 cell lines; however, OPCs derived from these LRRK2 lines specifically lost SEMA6 signaling due to a down-regulation of SEMA6A and PLXNA2. Pseudotemporal trajectory analysis revealed that SHH had significantly altered expression along the pseudotime, accompanied by higher expression levels in LRRK2 lines. We propose that dysfunctional semaphorin-plexin signaling, along with cilia movement and SHH signaling, might represent early events in PD pathology.

neuroscience↗

bioRxiv2024

Frontotemporal dementia patient-derived iPSC neurons show cell pathological hallmarks and evidence for synaptic dysfunction and DNA damage

Frontotemporal dementia (FTD) is the second most common cause of dementia in patients under 65 years, characterized by diverse clinical symptoms, neuropathologies, and genetic background. Synaptic dysfunction is suggested to play a major role in FTD pathogenesis. Disturbances in the synaptic function can also be associated with the C9orf72 repeat expansion (C9-HRE), the most common genetic mutation causing FTD. C9-HRE leads to distinct pathological hallmarks, such as C9orf72 haploinsufficiency and development of toxic RNA foci and dipeptide repeat proteins (DPRs). FTD patient brains, including those carrying the C9-HRE, are also characterized by neuropathologies involving accumulation of TDP-43 and p62/SQSTM1 proteins. This study utilized induced pluripotent stem cell (iPSC)-derived cortical neurons from C9-HRE-carrying or sporadic FTD patients and healthy control individuals. We report that the iPSC neurons derived from C9-HRE carriers developed typical C9-HRE-associated hallmarks, including RNA foci and DPR accumulation. All FTD neurons demonstrated increased TDP-43 nucleus-to-cytosolic shuttling and p62/SQSTM1 accumulation, and changes in nuclear size and morphology. In addition, the FTD neurons displayed reduced number and altered morphologies of dendritic spines and significantly altered synaptic function indicated by a decreased response to stimulation with GABA. These structural and functional synaptic disturbances were accompanied by upregulated gene expression in the FTD neurons related to synaptic function, including synaptic signaling, glutamatergic transmission, and pre- and postsynaptic membrane, as compared to control neurons. Pathways involved in DNA repair were significantly downregulated in FTD neurons. Only one gene, NUPR2, potentially involved in DNA damage response, was differentially expressed between the sporadic and C9-HRE-carrying FTD neurons. Our results show that the iPSC neurons from FTD patients recapitulate pathological changes of the FTD brain and strongly support the hypothesis of synaptic dysfunction as a crucial contributor to disease pathogenesis in FTD.

neuroscience↗