Biology subjects

Muegge, B.

Publications and source records attributed to Muegge, B..

3 recordsLinked to original sources

bioRxiv2025

EGR1 drives sex-differences in glioblastoma tumorigenicity

Although progress has been made in treating glioblastoma (GBM), with fewer than 5% of patients surviving more than 5 years after diagnosis. For reasons that are not well understood, females are roughly 60% as likely as males to develop GBM, and female patients consistently respond better to treatment than do males. Understanding the molecular etiology of these sex differences in tumor progression and resiliency to treatment could reveal potent new therapeutic targets, ultimately improving survival of both male and female GBM patients. Here we show that the transcription factor Egr1 is a primary mediator of sex differences in multiple GBM tumorigenic phenotypes. In multivariate analysis, high levels of EGR1 expression are correlated with shortened survival for male GBM patients only. To investigate the molecular mechanisms underlying this sex difference, we performed a genomic analysis in our established ex vivo murine model of sex differences, which showed that the transcription factors Egr1 and Klf5 preferentially recruit the transcriptional activator Brd4 to enhancers in male cells relative to female cells, explaining a previously made observation that Brd4 inhibitors reverse sex differences in GBM. Next, using murine and human primary GBM cells, we demonstrated that the small molecule compound SR18662, which downregulates Egr1 and its downstream target Klf5, abrogates GBM growth, migration, invasion, clonogenicity, and response to radiation in a sex-biased fashion. Finally, we knocked down Egr1 and Klf5 via CRISPRi in both untreated and SR18662-treated GBM cells to reveal the sex-biased anti-tumorigenic effects of SR18662 were largely due to Egr1 downregulation, independent of Klf5 downregulation. This result was replicated in vivo. Our results strongly indicate that an Egr1 regulon is a key determinant of sex differences in GBM. As EGR1 is implicated in the cancer biology of many cancers that also display sex differences in incidence and treatment response, our results are likely to be broadly applicable in oncology.

cancer biology↗

bioRxiv2021

Islet primary cilia motility controls insulin secretion

Primary cilia are specialized cell-surface organelles that mediate sensory perception and, in contrast to motile cilia and flagella, are thought to lack motility function. Here we show that primary cilia in pancreatic beta cells exhibit movement that is required for glucose-dependent insulin secretion. Beta cell cilia contain motor proteins conserved from those found in classic motile cilia, and their 3D motion is dynein-driven and dependent on ATP and glucose metabolism. Inhibition of cilia motion blocks beta cell calcium influx and insulin secretion. Beta cells from humans with type 2 diabetes have altered expression of cilia motility genes. Our findings redefine primary cilia as dynamic structures possessing both sensory and motile function and establish that pancreatic beta cell cilia movement plays a critical role in controlling insulin secretion.

cell biology↗

bioRxiv2020

Biofilm Formation and Virulence of Shigella flexneri is Modulated by pH of Gastrointestinal Tract

Shigella infections remain a major public health issue in developing countries. One model of Shigella pathogenesis suggests that the microfold epithelial cells in the small intestine are the preferred initial site of infection. However, a growing body of evidence supports an alternative model whereby Shigella primarily infects a much wider range of epithelial cells that reside primarily within the colon. Here, we investigated whether the luminal pH difference between the small intestine and colon could provide evidence in support of either model of Shigella flexneri pathogenesis. As virulence factors leading to cellular invasion are linked to biofilms in S. flexneri, we examined the effect of pH on S. flexneris ability to form and maintain adherent biofilms when induced by deoxycholate. We showed that a basic pH inhibited formation and dispersed pre-assembled mature biofilms while an acidic pH (similar to the colonic environment) did not have either of these effects. To further elucidate this phenomenon at the molecular level, we probed the transcriptomes of biofilms and S. flexneri grown in different pH conditions. We identified specific amino acid metabolic pathways (cysteine and arginine) that were enriched in the bacteria that formed the biofilms, but decreased upon pH increase. We then utilized a type III secretion system reporter strain to show that increasing pH reduced deoxycholate-induced virulence of S. flexneri in a dose dependent manner. Taken together, these experiments support a model whereby Shigella infection is favored in the colon because of the local pH differences in these organs.

microbiology↗