Biology subjects

Sela-Donenfeld, D.

Publications and source records attributed to Sela-Donenfeld, D..

6 recordsLinked to original sources

bioRxiv2023

Hindbrain boundaries as niches of neural progenitor/stem cells regulated by the extracellular matrix proteoglycan chondroitin sulphate.

The interplay between neural progenitor/stem cells (NPSC) and their extracellular matrix (ECM), is a crucial regulatory mechanism that determines their behavior. Nonetheless, how the ECM dictates internal processes remains elusive. The hindbrain is valuable to examine this relationship, as cells in the hindbrain boundaries (HB), which arise between any two neighboring rhombomeres, express the NPSC-marker Sox2 while being surrounded with the ECM molecule chondroitin sulphate proteoglycan (CSPG), in chick and mouse embryos. CSPG expression was used to isolate HB/Sox2+ cells for RNA-sequencing, revealing their distinguished molecular properties as typical NPSCs, which express known and newly-identified genes relating to stem cells, cancer, matrisome and cell-cycle. In contrast, the CSPG-/non-HB cells, displayed clear neural-differentiation transcriptome. To address whether CSPG is significant for hindbrain development, its expression was manipulated in vivo and in vitro. CSPG-manipulations shifted the stem versus differentiation state of HB cells, evident by their behavior and altered gene expression. These results provide novel understanding on the uniqueness of hindbrain boundaries as repetitive pools of NPSCs in-between the rapidly-growing rhombomeres, which rely on their microenvironment to maintain undifferentiated during development. SUMMARY:Transcriptomic analysis of hindbrain boundaries revels them to harbor cells with neural progenitor\stem cell properties that rely on local extracellular matrix to maintain their undifferentiated state.

developmental biology↗

bioRxiv2023

Maternal exposure to environmental levels of carbamazepine induces mild growth retardation in mouse embryos

As chemical pollution is constantly increasing, the impact on the environment and public health must be investigated. This study focuses on the anticonvulsant drug carbamazepine (CBZ), which is ubiquitously present in the environment. Due to its physicochemical properties and stability during wastewater treatment, CBZ is detected in reclaimed wastewater, surface water and groundwater. In water-scarce regions heavily relying on treated wastewater for crop irrigation, CBZ is detected in arable land, produce and even in humans consuming crops irrigated with recealimed wastewater. Aalthough environmental levels of CBZ are very low, risks associated with unintentional exposure to CBZ are essential to be revealed. In perinatal medicine, CBZ is a teratogen; its prescription to pregnant women increases the risk for fetal malformations. This raises the concern of whether environmental exposure to CBZ may also impact embryogenesis. Studies in zebrafish and chick embryos or in cell culture have indicated negative outcomes upon exposure to low CBZ levels. Yet, these systems do not recapitulate the manner by which human fetuses are exposed to pharmaceuticals via maternal uptake. Here, we employed the mouse model to determine whether maternal exposure to environmental-relevant doses of CBZ will impact embryonic development. No effects on fertility, number of gestation sacs, gross embryonic malformations or fetal survival were detected. Yet, embryos were growth-delayed compared to controls (p=0.0011), as manifested in lower embryonic stage and somite number, earlier morphological features and reduction in mitotically-active cells. This study provides the first evidence for the effect of environmental concentration of CBZ on the developmental kinetics of maternally-exposed mammalian embryos. While the developmental delay was relatively modest, its consistency in high number of biological replicates, together with the known implication of developmental delay on post-natal health, calls for further in-depth risk analyses to reveal the effects of pharmaceuticals released to the environment on public health.

developmental biology↗

bioRxiv2022

MMP2 loss leads to defective parturition and severe dystocia in mice

Parturition is the final step of mammalian reproduction and an essential process for the species survival. During pregnancy, the uterus is maintained quiescence which is important for fetal growth and development. However, at term, fundamental changes in myometrial contractility are initiated for efficient expulsion of the fetus. These changes involve tissue remodeling that requires changes in the extracellular matrix (ECM). The gelatinases subgroup of matrix metalloproteinases (MMPs), has only two members: MMP2 and MMP9, which are both known to participate in uterine ECM remodeling throughout the estrus cycle as well as during pregnancy, parturition and postpartum involution. Yet, no knowledge exists regarding their loss-of-function impact on the uterus. Here we investigated the effect of MMP2 and/or MMP9 genetic loss on parturition process. Single and double knockout (dKO) mice for MMP2 and/or MMP9 were used. We found high percentages of dystocia in mmp2-/-, mmp2-/-mmp9+/- and dKO females, but not in mmp9-/- females. Histological analysis of nulliparous uterine tissue of WT, mmp2-/-, mmp9-/- and dKO, at 8 weeks, 4 months and 8-9.5 months, revealed that the uterine tissue of mmp2-/- presents alterations in tissue size and structure, mainly when reaching to 8-9.5 months of age, including enlarged total tissue, myometrium, endometrium and luminal cavity. Additionally, Massons Trichrome staining suggested a mechanism of extensive fibrosis in mmp2-/- myometrium, which may lead to dystocia. Altogether, our research highlights a novel cause for dystocia pathology mediated by loss of MMP2 activity in uterine tissue during mammalian parturition.

physiology↗

bioRxiv2022

Initiation of fibronectin fibrillogenesis is an enzyme-dependent process

Fibronectin fibrillogenesis and mechanosensing both depend on integrin-mediated force transmission to the extracellular-matrix. However, force transmission is in itself dependent on fibrillogenesis, and fibronectin fibrils are found in soft embryos where high forces cannot be applied, suggesting that force cannot be the sole initiator of fibrillogenesis. Here we identify a nucleation step prior to force transmission, driven by fibronectin oxidation mediated by lysyl-oxidase enzyme family members. This oxidation induces fibronectin clustering that promotes early adhesion, alters cellular response to soft matrices, and enhances force transmission to the matrix. In contrast, absence of fibronectin oxidation abrogates fibrillogenesis, perturbs cell-matrix adhesion, and compromises mechanosensation. Moreover, fibronectin oxidation promotes cancer cells colony formation in soft agar as well as collective and single-cell migration. These results reveal a force-independent enzyme-dependent mechanism that initiates fibronectin fibrillogenesis, establishing a critical step in cell adhesion and mechanosensing.

cell biology↗

bioRxiv2022

HREM, RNAseq and cell-cycle analyses reveal the role of the G2/M-regulatory protein, Wee1, on the survivability of chicken embryos during diapause.

Avian blastoderm can enter into diapause when kept at low temperatures, and successfully resume development (SRD) when re-incubated in body-temperature. These abilities, which are largely affected by the temperature and duration of the diapause, are poorly understood at the cellular and molecular level. To determine how temperature affects embryonic morphology during diapause, High-Resolution Episcopic Microscopy (HREM) analysis was utilized. While blastoderms diapausing at 12{degrees}C for 28 days presented typical cytoarchitecture, similar to non-diapaused embryos, at 18{degrees}C much thicker blastoderms with higher cell-number were observed. RNAseq was conducted to discover the genes underlying these phenotypes, revealing differentially-expressed cell-cycle regulatory genes. Amongst them, Wee1, a negative-regulator of G2/M transition, was highly expressed at 12{degrees}C compared to 18{degrees}C. This finding suggested that cells at 12{degrees}C are arrested at the G2/M phase, as supported by bromodeoxyuridine incorporation (BrdU) assay and phosho-histone-H3 (pH3) immuno-staining. Inhibition of Wee1 during diapause at 12{degrees}C resulted in cell-cycle progression beyond the G2/M and augmented tissue volume, resembling the morphology of 18{degrees}C-diapaused embryos. These findings suggest that diapause at low temperatures leads to Wee1 upregulation which arrests the cell-cycle at the G2/M phase, promoting the perseverance of embryonic cytoarchitecture and future SRD. In contrast, Wee1 is not up-regulated during diapause at higher temperature, leading to continuous proliferation and maladaptive morphology associated with poor survivability. Combining HREM-based analysis with RNAseq and molecular manipulations, we present a novel mechanism that regulates the ability of diapaused-avian embryos to maintain their cytoarchitecture via cell-cycle arrest, which enables their SRD.

evolutionary biology↗

bioRxiv2021

How do avian embryos resume development following diapause? A new role for TGF-β in regulating pluripotency-related genes

Avian embryos can halt their development for long periods at low temperature in a process called diapause and successfully resume development when reincubated at maternal body temperature. Successful resumption of development depends on different factors, including temperature. We have recently shown that embryos that enter diapause at 18 {degrees}C present a significant reduction in their ability to develop normally when put back into incubation, compared to embryos entering diapause at 12 {degrees}C. However, the mechanisms underlying these differences are unknown. To address this question, transcriptome analysis was performed to compare the effect of diapause temperature on gene expression, and to identify pathways involved in the process. Genetic comparison and pathway-enrichment analysis revealed that TGF-{beta} and pluripotency-related pathways are differentially regulated at the two temperatures, with higher expression at 12 {degrees}C compared to 18 {degrees}C. Investigating the involvement of the TGF-{beta} pathway revealed an essential role for BMP4 in regulating the expression of the transcription factors Nanog and Id2, which are known to regulate pluripotency and self-renewal in embryonic stem cells. BMP4 gain- and loss-of-function experiments in embryos in diapause at the different temperatures revealed the main role of BMP4 in enabling resumption of normal development following diapause. Collectively, these findings identify molecular regulators that facilitate embryos ability to undergo diapause at different temperatures and resume a normal developmental program.

developmental biology↗