To better understand the role of ceRNA network in labor, transcriptome sequencing was performed on the myometrium of 17 parturients at different labor durations (0–24 h). Competing endogenous RNA (ceRNA) can also regulate the gene expression. The uterine contractility is gradually enhanced with the progression of labor, which is related to the gene expression of the myometrium. The maintenance of coordinated powerful episodic contractions of the uterus is the crucial factor for normal labor. Taken together, our results establish a mechanism for how mitotic proteins Bub3 and BuGZ functions in transcriptional regulation in a eukaryotic organism. The deposition of BuGZ along cat-3 chromatin hindered the recruitment of transcription activators GCN4/CPC1 and NC2 complex, thereby preventing the assembly of the transcriptional machinery. However, the zinc finger domains of BuGZ have no effects on DNA binding, although mutations of these highly conserved domains lead to loss of cat-3 repression. Further experiments demonstrated that BuGZ binds directly to the cat-3 gene and responses to cat-3 overexpression induced by oxidative stresses. Despite loss of the interaction, the amount of BuGZ mutant protein negatively correlated with the cat-3 expression level, indicating that BuGZ amount rather than Bub3-BuGZ interaction determines cat-3 transcription level. Our data indicate that BuGZ and Bub3 interact directly via the GLEBS domain of BuGZ. The absence of Bub3 caused a significant decrease in BuGZ protein levels.
Here, we demonstrate that Bub3 and BuGZ negatively regulate cat-3 transcription in the model filamentous fungus Neurospora crassa. In aerobic organisms, transcriptional regulation of catalase genes in response to developmental or environmental stimuli is necessary for redox homeostasis.
The spindle assembly checkpoint factors Bub3 and BuGZ play critical roles in mitotic process, but little is known about their roles in other cellular processes in eukaryotes. These findings suggest that BuGZ not only serves as a molecular chaperone for Bub3 but also enhances its loading onto kinetochores during prometaphase in a microtubule-dependent manner to promote chromosome alignment. Interestingly, we show that microtubules are required for the highest kinetochore loading of Bub3, BubR1, and CENP-E during prometaphase. This enhanced Bub3 loading is required for proper chromosome alignment and metaphase to anaphase progression. BuGZ also uses its microtubule-binding domain to enhance the loading of Bub3 to kinetochores that have assumed initial interactions with microtubules in prometaphase. Using its conserved GLEBS, BuGZ directly binds and stabilizes Bub3. By screening for mitotic regulators in the spindle envelope and matrix (Spemix), we identify a conserved Bub3 interacting and GLE-2-binding sequence (GLEBS) containing ZNF207 (BuGZ) that associates with spindle microtubules and regulates chromosome alignment. Equal chromosome segregation requires proper assembly of many proteins, including Bub3, onto kinetochores to promote kinetochore-microtubule interactions.
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