Welcome to the Ansel Lab!
MicroRNAs, transcription factors, and epigenetic regulation shape the gene expression programs that determine cell identity and function. The Ansel lab studies how these molecular mechanisms work together to control lymphocyte development, differentiation, and function in immunity.
We use in vitro cell differentiation systems, mouse genetics, disease models, and gene expression analyses in cells from human clinical samples to unravel the regulatory networks that underlie immunity and immune pathology, especially allergy and asthma.
Lymphocyte lineage decisions are critical for the development of protective immunity against a great diversity of pathogens, but improper or exaggerated responses also contribute to the development and pathology of autoimmune diseases, chronic inflammation, allergy, and asthma. Our primary experimental system is the differentiation of helper T cells, the central coordinators of adaptive immune responses. Upon immune activation, naïve CD4+ T cells can differentiate into several different helper T cell effectors subtypes (e.g. Th1, Th2, Th17, iTreg, Tfh, etc.). These lineages are defined by their characteristic gene expression programs and mediate distinct immune functions. We and many others have documented how these gene expression programs are controlled by external factors from other cells and the environment, inducible and lineage-specific transcription factors, the cis-regulatory DNA elements to which they bind, and epigenetic modifications that constrain chromatin accessibility at those sites. Aside from their importance in health and disease, the depth of our knowledge about the networks that control helper T cells makes them an attractive model for studying new basic mechanisms of gene regulation, such as noncoding RNAs.
Active projects in the laboratory mostly focus on miRNAs. We study how individual miRNA families regulate helper T cell differentiation and immune function, as well as the regulation of the miRNA pathway itself during immune responses. Naive CD4+ T cells that cannot produce any miRNAs exhibit reduced cell division and survival in response to immune stimuli. Surprisingly, they also undergo rapid unrestrained differentiation into effector cells. We have developed a screening technology that allows us to rapidly determine which specific miRNAs regulate each of these T cell behaviors, and a high throughput nanoscaled pipeline for determining miRNA expression patterns in small clinical samples (such as sorted T cell subsets from the airways of human asthmatic subjects, serum, sputum, and other sources of extracellular miRNAs, etc.). In addition, we discovered that T cells rapidly reset their miRNA repertoire upon activation. This process that involves ubiquitination and degradation of Argonaute proteins, but the signaling mechanisms and the fate of associated miRNAs remains unknown. This rapid change in miRNA expression may be important to allow T cells to change their gene expression programs and develop effector functions.
The major research goals of our laboratory are:
1) To define the molecular mechanisms that control miRNA homeostasis in lymphocytes, and determine how the miRNA repertoire is so dramatically remodeled during T cell activation.
2) To characterize the function of individual miRNAs that regulate T cell differentiation and immune effector functions.
3) To determine how the expression and function of miRNAs contribute to the pathogenic properties of T cells in human asthma.
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