TNFα increases tyrosine hydroxylase expression in human monocytes.

Most, if not all, peripheral immune cells in humans and animals express tyrosine hydroxylase (TH), the rate limiting enzyme in catecholamine synthesis. Since TH is typically studied in the context of brain catecholamine signaling, little is known about changes in TH production and function in peripheral immune cells. This knowledge gap is due, in part, to the lack of an adequately sensitive assay to measure TH in immune cells expressing lower TH levels compared to other TH expressing cells.

Non-monotonic dependence of stiffness on actin crosslinking in cytoskeleton composites.

The cytoskeleton is able to precisely tune its structure and mechanics through interactions between semiflexible actin filaments, rigid microtubules and a suite of crosslinker proteins. However, the role that each of these components, as well as the interactions between them, plays in the dynamics of the composite cytoskeleton remains an open question. Here, we use optical tweezers microrheology and fluorescence confocal microscopy to reveal the surprising ways in which actin crosslinking tunes the viscoelasticity and mobility of actin-microtubule composites from steady-state to the highly nonlinear regime.

A novel approach to study markers of dopamine signaling in peripheral immune cells.

Human monocytes express known markers of dopamine synthesis, storage and clearance, including dopamine transporter (DAT), tyrosine hydroxylase (TH), all subtypes of dopamine receptors and vesicular monoamine transporter 2 (VMAT2). Immunohistochemical and immunofluorescent methodologies have traditionally been employed to determine DAT and TH expression in the CNS, their detection in the blood and specifically in the peripheral monocytes has not been studied by flow cytometry. Flow cytometry assays are widely used in medicine and in basic, preclinical or clinical research to quantify physical and chemical characteristics of target cell populations.

Varying crosslinking motifs drive the mesoscale mechanics of actin-microtubule composites.

The cytoskeleton precisely tunes its mechanics by altering interactions between semiflexible actin filaments, rigid microtubules, and crosslinking proteins. We use optical tweezers microrheology and confocal microscopy to characterize how varying crosslinking motifs impact the mesoscale mechanics and mobility of actin-microtubule composites. We show that, upon subtle changes in crosslinking patterns, composites can exhibit two distinct classes of force response - primarily elastic versus more viscous.