Biology subjects

Mills, M.

Publications and source records attributed to Mills, M..

3 recordsLinked to original sources

bioRxiv2018

Wound-induced polyploidization is driven by Myc and supports tissue repair in the presence of DNA damage

Tissue repair requires either polyploid cell growth or cell division, but the molecular mechanism promoting polyploidy and limiting proliferation remains poorly understood. Here we find that injury to the adult Drosophila epithelium causes cells to enter the endocycle through the activation of Yorkie dependent genes (myc, e2f1, or cycE). Myc is even sufficient to induce the endocycle in the post-mitotic epithelium. As result, epithelial cells enter S phase but mitosis is blocked by inhibition of mitotic gene expression. The mitotic cell cycle program can be activated by simultaneously expressing the mitotic activator, Stg, while genetically depleting fzr. However, forcing cells to undergo mitosis is detrimental to wound repair as the adult fly epithelium accumulates DNA damage and mitotic errors ensue when cells are forced to proliferate. In conclusion, we find that wound-induced polyploidization enables tissue repair when cell division is not a viable option.

cell biology↗

bioRxiv2018

Direct Observation of Topoisomerase IA Gate Dynamics

Type IA topoisomerases cleave single-stranded DNA and relieve negative supercoils in discrete steps corresponding to the passage of the intact DNA strand through the cleaved strand. Although it is assumed type IA topoisomerases accomplish this strand passage via a protein-mediated DNA gate, opening of this gate has never been observed. We developed a single-molecule assay to directly measure gate opening of the E. coli type IA topoisomerases I and III. We found that following cleavage of single-stranded DNA, the protein gate opens by as much as 6.6 nm and can close against forces in excess of 16 pN. Key differences in the cleavage, ligation and gate dynamics of these two enzymes provide insights into their different cellular functions. The single-molecule results are broadly consistent with conformational changes obtained from molecular dynamics simulations. These results allow us to develop a mechanistic model of type IA topoisomerase-ssDNA interactions.

biophysics↗

bioRxiv2017

A suite of transgenic driver and reporter mouse lines with enhanced brain cell type targeting and functionality

Modern genetic approaches are powerful in providing access to diverse types of neurons within the mammalian brain and greatly facilitating the study of their function. We here report a large set of driver and reporter transgenic mouse lines, including 23 new driver lines targeting a variety of cortical and subcortical cell populations and 26 new reporter lines expressing an array of molecular tools. In particular, we describe the TIGRE2.0 transgenic platform and introduce Cre-dependent reporter lines that enable optical physiology, optogenetics, and sparse labeling of genetically-defined cell populations. TIGRE2.0 reporters broke the barrier in transgene expression level of single-copy targeted-insertion transgenesis in a wide range of neuronal types, along with additional advantage of a simplified breeding strategy compared to our first-generation TIGRE lines. These novel transgenic lines greatly expand the repertoire of high-precision genetic tools available to effectively identify, monitor, and manipulate distinct cell types in the mouse brain.

neuroscience↗