Developmental, cellular, and behavioral phenotypes in a mouse model of congenital hypoplasia of the dentate gyrus
ELIFE
Authors: Rattner, Amir; Terrillion, Chantelle E.; Jou, Claudia; Kleven, Tina; Hu, Shun Felix; Williams, John; Hou, Zhipeng; Aggarwal, Manisha; Mori, Susumu; Shin, Gloria; Goff, Loyal A.; Witter, Menno P.; Pletnikov, Mikhail; Fenton, Andre A.; Nathans, Jeremy
Abstract
In the hippocampus, a widely accepted model posits that the dentate gyrus improves learning and memory by enhancing discrimination between inputs. To test this model, we studied conditional knockout mice in which the vast majority of dentate granule cells (DGCs) fail to develop - including nearly all DGCs in the dorsal hippocampus - secondary to eliminating Wntless (Wls) in a subset of cortical progenitors with Gfap-Cre. Other cells in the Wls(fl/-);Gfap-Cre hippocampus were minimally affected, as determined by single nucleus RNA sequencing. CA3 pyramidal cells, the targets of DGC-derived mossy fibers, exhibited normal morphologies with a small reduction in the numbers of synaptic spines. Wls(fl/-);Gfap-Cre mice have a modest performance decrement in several complex spatial tasks, including active place avoidance. They were also modestly impaired in one simpler spatial task, finding a visible platform in the Morris water maze. These experiments support a role for DGCs in enhancing spatial learning and memory.
Overexpression of transcription factor Foxa1 and target genes remediate therapeutic protein production bottlenecks in Chinese hamster ovary cells
BIOTECHNOLOGY AND BIOENGINEERING
Authors: Berger, Audrey; Le Fourn, Valerie; Masternak, Jacqueline; Regamey, Alexandre; Bodenmann, Iris; Girod, Pierre-Alain; Mermod, Nicolas
Abstract
Despite extensive research conducted to increase protein production from Chinese hamster ovary (CHO) cells, cellular bottlenecks often remain, hindering high yields. In this study, a transcriptomic analysis led to the identification of 32 genes that are consistently upregulated in high producer clones and thus might mediate high productivity. Candidate genes were associated with functions such as signaling, protein folding, cytoskeleton organization, and cell survival. We focused on two engineering targets, Erp27, which binds unfolded proteins and the Erp57 disulfide isomerase in the endoplasmic reticulum, and Foxa1, a pioneering transcription factor involved in organ development. Erp27 moderate overexpression increased production of an easy-to-express antibody, whereas Erp27 and Erp57 co-overexpression increased cell density, viability, and the yield of difficult-to-express proteins. Foxa1 overexpression increased cell density, cell viability, and easy- and difficult-to-express protein yields, whereas it decreased reactive oxygen species late in fed-batch cultures. Foxa1 overexpression upregulated two other candidate genes that increased the production of difficult- and/or easy-to-express proteins, namely Ca3, involved in protecting cells from oxidative stress, and Tagap, involved in signaling and cytoskeleton remodeling. Overall, several genes allowing to overcome CHO cell bottlenecks were identified, including Foxa1, which mediated multiple favorable metabolic changes that improve therapeutic protein yields.