Heterogametic species require chromosome-wide gene regulation to compensate for differences in sex chromosome gene dosage. In Drosophila melanogaster, transcriptional output from the single male X-chromosome is equalized to that of XX females by recruitment of the Male Specific Lethal (MSL) complex, which increases transcript levels of active genes two-fold. MSL complex contains several protein components and two non-coding roX (RNA on the X) RNAs that are transcriptionally activated by MSL complex. We previously discovered that targeting of MSL complex to the X-chromosome is dependent on the Chromatin-Linked Adapter for MSL Protein (CLAMP) zinc finger protein. To better understand CLAMP function, we used the CRISPR/Cas9 genome editing system to generate a frameshift mutation in the clamp gene that eliminates expression of CLAMP protein. We found that clamp null females die at the third instar larval stage, while almost all clamp null males die at earlier developmental stages. Moreover, we found that in clamp null females roX gene expression is activated whereas in clamp null males roX gene expression is reduced. Therefore, CLAMP regulates roX abundance in a sex-specific manner. Our results provide new insights into sex-specific gene regulation by an essential transcription factor.

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Antenatal administration of synthetic glucocorticoids (sGC) is the standard of care for women at risk for preterm labor before 34 gestational weeks. Despite their widespread use, the type of sGC used and their dose or the dosing regimens are not standardized in the United States of America or worldwide. Several studies have identified neural deficits and the increased risk for cognitive and psychiatric disease later in life for children administered sGC prenatally. However, the precise molecular and cellular targets of GC action in the developing brain remain largely undefined. In this study, we demonstrate that a single dose of glucocorticoid during mid-gestation in mice leads to enhanced proliferation in select cerebral cortical neural stem/progenitor cell populations. These alterations are mediated by dose-dependent changes in the expression of cell cycle inhibitors and in genes that promote cell cycle re-entry. This leads to changes in neuronal number and density in the cerebral cortex at birth, coupled to long-term alterations in neurite complexity in the prefrontal cortex and hippocampus in adolescents, and changes in anxiety and depressive-like behaviors in adults.

Glucocorticoids are given to pregnant women at risk for premature delivery to promote lung maturation. Despite reports of detrimental effects of glucocorticoids on telencephalic neural stem/progenitor cells (NSPCs), the regional and cellular expression of the glucocorticoid receptor (GR) in various NSPC populations in the intact brain has not been thoroughly assessed. Therefore in this study we performed a detailed analysis of GR protein expression in the developing mouse ventral and dorsal telencephalon in vivo. At embryonic day 11.5 (E11.5), the majority of Pax6-positive radial glial cells (RGCs) and Tbr2-positive intermediate progenitor cells (IPCs) expressed nuclear GR, while a small number of RGCs on the apical ventricular zone (aVZ), expressed cytoplasmic GR. However, on E13.5, the latter population of RGCs increased in size, whereas abventricular NSPCs and especially neurons of the cortical plate, expressed nuclear GR. In IPCs, GR was always nuclear. A similar expression profile was observed throughout the ventral telencephalon, hippocampus and olfactory bulb, with NSPCs of the aVZ primarily expressing cytoplasmic GR, while abventricular NSPCs and mature cells primarily expressed nuclear GR. Close to birth, nuclear GR accumulated within specific cortical areas such as layer V, the subplate and CA1 area of the hippocampus. In summary, our data show that GR protein is present in early NSPCs of the dorsal and ventral telencephalon at E11.5 and primarily occupies the nucleus. Moreover, our study suggests that the subcellular localization of the receptor may be subjected to region and neurodevelopmental stage-specific regulation.