Northwestern University

Apr
11
Thu 10:00 AM

BMG Seminar: "Building Patterning-Dependent Chromatin States During Embryogenesis" -Shelby Blythe, PhD

When: Thursday, April 11, 2019
10:00 AM - 11:00 AM  

Where: Robert H Lurie Medical Research Center, Baldwin Auditorium, 303 E. Superior, Chicago, IL 60611 map it

Audience: Faculty/Staff - Student - Post Docs/Docs - Graduate Students

Contact: Vanessa Hughes   312.503.5229

Group: Biochemistry & Molecular Genetics Seminar Series

Category: Lectures & Meetings

Description:

The Department of Biochemistry and Molecular Genetics Departmental Seminar Series presents:

In my seminar, I will discuss advances in understanding how Drosophila embryos build the initial homogeneous “ground state” of chromatin structure that will sustain the initial rounds of developmental patterning. I will also address how elaborations on this starting state of chromatin architecture are programmatically introduced by the developmental cues that drive cell fate specification.

Drosophila embryos undergo Zygotic Genome Activation having established a homogeneous chromatin landscape common to all somatic cells of the embryo. Ubiquitously expressed pioneer factors, such as Zelda, establish this initial ‘ground state’ of chromatin structure. Over the next 24 hours of development, cell fate specification and differentiation will take place, bringing with it the emergence of cell-type specific chromatin organization. How do such patterns emerge, and how do developmental patterning systems drive these changes? To address this, I have profiled chromatin accessibility by ATAC-seq between Zygotic Genome Activation and gastrulation comparing wild-type embryos with those simultaneously deficient for all maternal patterning systems. Unlike wild type embryos, quintuple bicoid oskar capicua torsolike Toll[RM9] mutants develop with an apparent single uniform cell identity that carries a molecular signature of posterior endodermal progenitors. I demonstrate that with the exception of Bicoid, maternal systems drive patterning events largely constrained by the initial state of chromatin structure. However, distinct zygotic targets of maternal patterning systems drive regionalized chromatin accessibility patterns, resulting in emergent heterogeneity. One single factor, odd-paired (human homolog: Zic2), displays pioneer-like function and accounts for ~30% of all new accessibility states that emerge in response to maternal patterning cues. Such patterning-dependent changes in chromatin accessibility states represent the emergence of ‘new’ information in the genome, occurring largely at previously silent cis-regulatory modules that are typically not bound by maternal pioneers such as Zelda and GAGA. Future work will involve testing the relative impact of regulating the emergence of such accessibility states in space and time.

Shelby Blythe, PhD
Assistant Professor of Molecular Biosciences
Northwestern University Weinberg College of Arts and Sciences


 

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