Seizure-induced LIN28A disrupts pattern separation via aberrant hippocampal neurogenesis
In-Young Choi, Jung-Ho Cha, Seong Yun Kim, Jenny Hsieh, Kyung-Ok Cho
In-Young Choi, Jung-Ho Cha, Seong Yun Kim, Jenny Hsieh, Kyung-Ok Cho
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Research Article Neuroscience Stem cells

Seizure-induced LIN28A disrupts pattern separation via aberrant hippocampal neurogenesis

Abstract

Prolonged seizures can disrupt stem cell behavior in the adult hippocampus, an important brain structure for spatial memory. Here, using a mouse model of pilocarpine-induced status epilepticus (SE), we characterized spatiotemporal expression of Lin28a mRNA and proteins after SE. Unlike Lin28a transcripts, induction of LIN28A protein after SE was detected mainly in the subgranular zone, where immunoreactivity was found in progenitors, neuroblasts, and immature and mature granule neurons. To investigate roles of LIN28A in epilepsy, we generated Nestin-Cre:Lin28aloxP/loxP (conditional KO [cKO]) and Nestin-Cre:Lin28a+/+ (WT) mice to block LIN28A upregulation in all neuronal lineages after acute seizure. Adult-generated neuron- and hippocampus-associated cognitive impairments were absent in epileptic LIN28A-cKO mice, as evaluated by pattern separation and contextual fear conditioning tests, respectively, while sham-manipulated WT and cKO animals showed comparable memory function. Moreover, numbers of hilar PROX1-expressing ectopic granule cells (EGCs), together with PROX1+/NEUN+ mature EGCs, were significantly reduced in epileptic cKO mice. Transcriptomics analysis and IHC validation at 3 days after pilocarpine administration provided potential LIN28A downstream targets such as serotonin receptor 4. Collectively, our findings indicate that LIN28A is a potentially novel target for regulation of newborn neuron-associated memory dysfunction in epilepsy by modulating seizure-induced aberrant neurogenesis.

Authors

In-Young Choi, Jung-Ho Cha, Seong Yun Kim, Jenny Hsieh, Kyung-Ok Cho

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Figure 7

Transcriptomics analysis of hippocampi from LIN28A cKO WT and -cKO mice at 3 d after pilocarpine-induced status epilepticus (SE).

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Transcriptomics analysis of hippocampi from LIN28A cKO WT and -cKO mice ...
(A) Experimental timeline. (B) Hierarchical clustering between LIN28A WT and LIN28A-cKO mice. (C) Multidimensional scaling plot demonstrating 3 distinct groups among sham-WT, sham-cKO, SE-WT, and SE-cKO. (D) GSEA enrichment plot and heatmap of differentially expressed genes (DEGs) with neurotransmitter receptor activity in pilocarpine-treated LIN28A WT and LIN28A-cKO mice. (E) Graphs showing the relative mRNA expression of several DEGs in the hippocampus. Note that Htr4 expression was significantly increased, whereas Htr2c and Htr1b transcription was downregulated in pilocarpine-treated LIN28A-cKO compared with WT mice. Htr4: Welch’s ANOVA test without outlier, followed by 2-stage linear step-up procedure of Benjamini, Krieger, and Yekutieli post hoc test. P = 0.010, W(3.000, 20.500) = 4.835. Sham-WT (n = 12), sham-cKO (n = 11), SE-WT (n = 11), SE-cKO (n = 12). Htr2c: Kruskal-Wallis H test without outlier, followed by 2-stage linear step-up procedure of Benjamini, Krieger, and Yekutieli post hoc test. P = 0.005, H = 12.480. Sham-WT (n = 12), sham-cKO (n = 11), SE-WT (n = 13), SE-cKO (n = 12). Htr1b: Kruskal-Wallis H test without outlier, followed by 2-stage linear step-up procedure of Benjamini, Krieger, and Yekutieli post hoc test. P = 0.001, H = 16.060. For pilocarpine-treated animals, additional Mann-Whitney U test was performed. P = 0.014, U = 47.500. Sham-WT (n = 12), sham-cKO (n = 13), SE-WT (n = 17), SE-cKO (n = 12). Data are presented as mean ± SEM. *P < 0.05, **P < 0.01,#P < 0.05 vs. SE-WT. (F) Representative microscopic images showing HTR4- and LIN28A-immunoreactive cells in the subgranular zone (SGZ) of pilocarpine-treated LIN28A WT and LIN28A-cKO mice. White arrowheads indicate a double-immunoreactive cell in SGZ. Experiment was independently replicated 3 times. Scale bar: 20 μm.