Cnih3 Deletion Dysregulates Dorsal Hippocampal Transcription Across the Estrous Cycle.

In females, the hippocampus-a critical brain region for coordination of learning, memory, and behavior-displays altered physiology and behavioral output across the estrous or menstrual cycle. However, the molecular effectors and cell types underlying these observed cyclic changes have only been partially characterized to date. Recently, profiling of mice null for the AMPA receptor trafficking gene Cnih3 have demonstrated estrous-dependent phenotypes in dorsal hippocampal synaptic plasticity, composition, and learning/memory. We therefore profiled dorsal hippocampal transcriptomes from female mice in each estrous cycle stage, and contrasted it with that of males, across wildtype and Cnih3 mutants. In wildtypes, we identified only subtle differences in gene expression between the sexes, while comparing estrous stages to one another revealed up to >1000 differentially expressed genes. These estrous-responsive genes are especially enriched in gene markers of oligodendrocytes and the dentate gyrus, and in functional gene sets relating to estrogen response, potassium channels, and synaptic gene splicing. Surprisingly, Cnih3 knockouts showed far broader transcriptomic differences between estrous cycle stages and males. Moreover, Cnih3 knockout drove subtle but extensive expression changes accentuating sex differential expression at diestrus and estrus. Altogether, our profiling highlights cell types and molecular systems potentially impacted by estrous-specific gene expression patterns in the adult dorsal hippocampus, enabling mechanistic hypothesis generation for future studies of sex-differential neuropsychiatric function and dysfunction. Moreover, these findings suggest an unrecognized role of Cnih3 in buffering against transcriptional effects of estrous, providing a candidate molecular mechanism to explain estrous-dependent phenotypes observed with Cnih3 loss. Significance Statement Cnih3 mutants show estrous-dependent alterations in learning, as well as physiological and anatomical changes in the dorsal hippocampus. However, the transcriptomic consequences of the estrous cycle on gene expression in the dorsal hippocampus of mice, including of Cnih3 mutants, have not been characterized. Here, we identify candidate cell types, pathways, and gene regulators putatively involved in estrous-dependent gene expression in wildtype mice. We then contrast these with dorsal hippocampal transcriptomics in Cnih3 knockout mice. Utilizing our wild-type data as a reference, we demonstrate that Cnih3 knockout mice have accentuated transcriptional responses across the estrous cycle.