Biology subjects

Molina, A.

Publications and source records attributed to Molina, A..

21 records · Page 2Linked to original sources

bioRxiv2019

Functional characterization of genes mediating cell wall metabolism and responses to plant cell wall integrity impairment

Plant cell walls participate in all plant-environment interactions. Maintaining cell wall integrity (CWI) during these interactions is essential. This realization led to increased interest in CWI and resulted in knowledge regarding early perception and signalling mechanisms active during CWI maintenance. By contrast, knowledge regarding processes mediating changes in cell wall metabolism upon CWI impairment is very limited. To identify genes involved and to investigate their contributions to the processes we selected 23 genes with altered expression in response to CWI impairment and characterized the impact of T-DNA insertions in these genes on cell wall composition using Fourier-Transform Infrared Spectroscopy (FTIR) in Arabidopsis thaliana seedlings. Insertions in 14 genes led to cell wall phenotypes detectable by FTIR. A detailed analysis of four genes found that their altered expression upon CWI impairment is dependent on THE1 activity, a key component of CWI maintenance. Phenotypic characterizations of insertion lines suggest that the four genes are required for particular aspects of CWI maintenance, cell wall composition or resistance to Plectosphaerella cucumerina infection in adult plants. Taken together, the results implicate the genes in responses to CWI impairment, cell wall metabolism and/or pathogen defence, thus identifying new molecular components and processes relevant for CWI maintenance.

plant biology↗

bioRxiv2018

Mathematical modeling supports fate restriction in neurogenic progenitors of the embryonic ventral spinal cord

In the developing neural tube in chicken and mammals, neural stem cells proliferate and differentiate according to a stereotyped spatio-temporal pattern. Several actors have been identified in the control of this process, from tissue-scale morphogens patterning (Shh, BMP) to intrinsic determinants in neural progenitor cells. In a previous study (Bonnet et al. eLife 7, 2018), we have shown that the CDC25B phosphatase promotes the transition from proliferation to differentiation in a cell-cycle independent fashion. In this study, we set up a mathematical model linking progenitor modes of division to the dynamics of progenitors and differentiated populations. Here, we build on this previous model to propose a complete dynamical picture of this process. We start from the standard model in which progenitors are homogeneous and can perform any type of divisions (proliferative division yielding two progenitors, asymmetric neurogenic divisions yielding one progenitor and one neuron, and terminal symmetric divisions yielding two neurons). We constraint this model using published data about mode of divisions and population dynamics of progenitors/neurons at different developmental stages (Saade et al. Cell Reports 4, 2013), and check the effect of CDC25B gain of function in this context. Next, we explore the scenarios in which progenitors population is actually split into two different pools, one of which composed of cells that have lost the capacity to perform proliferative divisions (fate restriction). We show that one such scenario appears relevant and calls for further identification of the alternative role of CDC25B in such a fate restriction.

developmental biology↗

bioRxiv2017

Neurogenic decisions require a cell cycle independent function of the CD25B phosphatase

A fundamental issue in developmental biology and in organ homeostasis is understanding the molecular mechanisms governing the balance between stem cell maintenance and differentiation into a specific lineage. Accumulating data suggest that cell cycle dynamics plays a major role in the regulation of this balance. Here we show that the G2/M cell cycle regulator CDC25B phosphatase is required in mammals to finely tune neuronal production in the neural tube. We show that in chick neural progenitors, CDC25B activity is both required and sufficient to stimulate neurogenic divisions and to promote neuronal differentiation. We design a mathematical model showing that within a limited period of time, cell cycle length modifications cannot account for changes in the ratio of the mode of division. Using a CDC25B point mutation that cannot interact with CDK, we show that part of CDC25B activity on neurogenic divisions is independent of its action on the cell cycle.

developmental biology↗