<i>Escherichia coli</i> Affects Expression of Circadian Clock Genes in Human Hepatoma Cells

• Main Authors: Urša Kovač, Zala Žužek, Lucija Raspor Dall’Olio, Katka Pohar, Alojz Ihan, Miha Moškon, Damjana Rozman, Marjanca Starčič Erjavec
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Microorganisms
• Subjects: intestinal microbiota; <i>Escherichia coli</i>; circadian clock; circadian rhythm; HepG2
• Online Access: https://www.mdpi.com/2076-2607/9/4/869

Recent research has indicated that dysbiosis of the gut microbiota can lead to an altered circadian clock of the mammalian host. Herein we developed an original system that allows real-time circadian studies of human HepG2 hepatoma cells co-cultured with bacteria. The HepG2 cells with stably integrated firefly luciferase reporter under the control of <i>PERIOD2</i> promoter were co-cultured with <i>E. coli</i> strains isolated from human fecal samples from healthy individuals. The two <i>E. coli</i> strains differ in the phylogenetic group and the number of ExPEC virulence-associated genes: BJ17 has only two, and BJ23 has 15 of 23 tested. In the first 24 h, the <i>E. coli</i> BJ17 affected the HepG2 circadian clock more than BJ23. Cosinor analysis shows a statistically significant change in the amplitude of <i>PER1</i> and <i>2</i> and the phase advance of <i>PER3.</i> A high percentage of necrotic and apoptotic cells occurred at 72 h, while a correlation between the number of ExPEC genes and the influence on the HepG2 core clock gene expression was observed. Our study reveals that the <i>E. coli</i> genetic background is important for the effect on the mammalian circadian clock genes, indicating possible future use of probiotic <i>E. coli</i> strains to influence the host circadian clock.