Biology subjects

Muniz, L.

Publications and source records attributed to Muniz, L..

3 recordsLinked to original sources

bioRxiv2025

Hyper-ovulation in an ovarian-specific transgenic mouse model.

Ovulation is a fundamental prerequisite for achieving successful reproduction. In vertebrates, ovulation is controlled by the cyclical action of hormones, particularly the gonadotropins such as follicle stimulating hormone (FSH) and luteinizing hormone (LH). A critical component of the intracellular activity of these two hormones is relayed by the second messenger cAMP. Although it is well established that a family of transcription factors facilitate cAMP mediated gene expression, it remains unknown how these factors directly affect ovulation. In particular, the Inducible cAMP Early Repressor (ICER) has been implicated in the transcriptional repression of FSH inducible genes during folliculogenesis. Here we show, using an ovarian-specific transgenic mouse model that ICER potentiates ovulation. We observed a twofold rate increase in ovulation for transgenic mice when compared to the wild type in response to exogenous gonadotropin treatment. Furthermore, mature cycling transgenic mice display a significantly enhanced ovulation rate compared to the wild-type. The observed changes in ovulation in the transgenic females are accompanied by altered gonadotropins production and gene expression. Most significantly, the expression of inhibin alpha subunit (INHA) was found to be about 5-fold higher in the transgenic mice. These observations may aid in unraveling some of the molecular mechanisms underlying ovulation and be relevant to the development of novel reproductive technologies. Summary SentenceGeneration of an FSH inducible ovarian specific FLAG-ICER-II(C) Tg Mice results in hyper-ovulation upon gonadotropin stimulation.

developmental biology↗

bioRxiv2022

siRNAs targeting a chromatin-associated RNA induce its transcriptional silencing in human cells

Transcriptional gene silencing by small interfering RNAs (siRNAs) has been widely described in various species, such as plants or fission yeasts. In mammals, its extent remained somewhat debated. Previous studies showed that siRNAs targeting gene promoters can induce the silencing of the targeted promoter, although the involvement of off-target mechanisms was also suggested. Here, by nascent RNA capture and RNA Pol II ChIP, we show that siRNAs targeting a chromatin-associated non-coding RNA induce its transcriptional silencing. Deletion of the sequence targeted by one of these siRNAs on the two alleles by genome editing further show that this silencing is due to base pairing of the siRNA to the target. Moreover, by using cells with heterozygous deletion of the target sequence, we show that only the wild type allele, but not the deleted allele, is silenced by the siRNA, indicating that transcriptional silencing occurs only in cis. Finally, we demonstrate that both Ago1 and Ago2 are involved in this transcriptional silencing. Altogether, our data demonstrate that siRNAs targeting a chromatin-associated RNA at distance from its promoter induce its transcriptional silencing. Our results thus extend the possible repertoire of endogenous or exogenous interfering RNAs.

molecular biology↗

bioRxiv2020

Circular ANRIL isoforms switch from repressors to activators of p15/CDKN2B expression during RAF1 oncogene-induced senescence

Long non-coding RNAs (ncRNAs) are major regulators of gene expression and cell fate. The INK4 locus encodes the tumour suppressor proteins p15INK4b, p16INK4a and p14ARF required for cell cycle arrest and whose expression increases during senescence. ANRIL is a ncRNA antisense to the p15 gene. In proliferative cells, ANRIL prevents senescence by repressing INK4 genes through the recruitment of Polycomb-group proteins. In models of replicative and RASval12 oncogene-induced senescence (OIS), the expression of ANRIL and Polycomb proteins decreases, thus allowing INK4 derepression. Here, we found in a model of RAF1 OIS that ANRIL expression rather increases, due in particular to an increased stability. This led us to search for circular ANRIL isoforms, as circular RNAs are rather stable species. We found that the expression of two circular ANRIL increases in several OIS models (RAF1, MEK1 and BRAF). In proliferative cells, they repress p15 expression, while in RAF1 OIS, they promote full induction of p15, p16 and p14ARF expression. Further analysis of one of these circular ANRIL shows that it interacts with Polycomb proteins and decreases EZH2 Polycomb protein localization and H3K27me3 at the p15 and p16 promoters, respectively. We propose that changes in the ratio between Polycomb proteins and circular ANRIL isoforms allow these isoforms to switch from repressors of p15 gene to activators of all INK4 genes in RAF1 OIS. Our data reveal that regulation of ANRIL expression depends on the senescence inducer and underline the importance of circular ANRIL in the regulation of INK4 gene expression and senescence.

molecular biology↗