The Rho family GEF Asef2 regulates cell migration in three dimensional (3D) collagen matrices through myosin II.

Cell migration is fundamental to a variety of physiological processes, including tissue development, homeostasis, and regeneration. Migration has been extensively studied with cells on 2-dimensional (2D) substrates, but much less is known about cell migration in 3D environments. Tissues and organs are 3D, which is the native environment of cells in vivo, pointing to a need to understand migration and the mechanisms that regulate it in 3D environments.

Activation of Rac by Asef2 promotes myosin II-dependent contractility to inhibit cell migration on type I collagen.

Non-muscle myosin II (MyoII) contractility is central to the regulation of numerous cellular processes, including migration. Rho is a well-characterized modulator of actomyosin contractility, but the function of other GTPases, such as Rac, in regulating contractility is currently not well understood. Here, we show that activation of Rac by the guanine nucleotide exchange factor Asef2 (also known as SPATA13) impairs migration on type I collagen through a MyoII-dependent mechanism that enhances contractility.

Glia co-culture with neurons in microfluidic platforms promotes the formation and stabilization of synaptic contacts.

Two novel microfluidic cell culture schemes, a vertically-layered set-up and a four chamber set-up, were developed for co-culturing central nervous system (CNS) neurons and glia. The cell chambers in these devices were separated by pressure-enabled valve barriers, which permitted us to control communication between the two cell types. The unique design of these devices facilitated the co-culture of glia with neurons in close proximity (∼50-100 μm), differential transfection of neuronal populations, and dynamic visualization of neuronal interactions, such as the development of synapses.

The endosomal adaptor protein APPL1 impairs the turnover of leading edge adhesions to regulate cell migration.

Cell migration is a complex process that requires the integration of signaling events that occur in distinct locations within the cell. Adaptor proteins, which can localize to different subcellular compartments, where they bring together key signaling proteins, are emerging as attractive candidates for controlling spatially coordinated processes. However, their function in regulating cell migration is not well understood.

A versatile valve-enabled microfluidic cell co-culture platform and demonstration of its applications to neurobiology and cancer biology.

A versatile microfluidic platform allowing co-culture of multiple cell populations in close proximity with separate control of their microenvironments would be extremely valuable for many biological applications. Here, we report a simple and compact microfluidic platform that has these desirable features and allows for real-time, live-cell imaging of cell-cell interactions. Using a pneumatically/hydraulically controlled poly(dimethylsiloxane) (PDMS) valve barrier, distinct cell types can be cultured in side-by-side microfluidic chambers with their optimum culture media and treated separately without affecting the other cell population.

An APPL1/Akt signaling complex regulates dendritic spine and synapse formation in hippocampal neurons.

The formation and plasticity of dendritic spines and synapses, which are poorly understood on a molecular level, are critical for cognitive functions, such as learning and memory. The adaptor protein containing a PH domain, PTB domain, and leucine zipper motif (APPL1) is emerging as a critical regulator of various cellular processes in non-neuronal cells, but its function in the nervous system is not well understood. Here, we show that APPL1 localizes to dendritic spines and synapses and regulates the development of these structures in hippocampal neurons.

Co-culture of neurons and glia in a novel microfluidic platform.

In this study, we developed a microfluidic cell co-culture platform that permits individual manipulation of the microenvironment of different cell types. Separation of the cell culture chambers is controlled by changing the position of a microfabricated valve, which serves as a barrier between the chambers. This unique feature of our platform allowed us to maintain healthy co-cultures of hippocampal neurons and glia for several weeks under optimal conditions.

The Rho-family GEF Asef2 activates Rac to modulate adhesion and actin dynamics and thereby regulate cell migration.

Asef2 is a recently identified Rho-family guanine nucleotide exchange factor (GEF) that has been implicated in the modulation of actin, but its function in cell migration and adhesion dynamics is not well understood. In this study, we show that Asef2 is an important regulator of cell migration and adhesion assembly and disassembly (turnover). Asef2 localizes with actin at the leading edge of cells.

N-wasp and the arp2/3 complex are critical regulators of actin in the development of dendritic spines and synapses.

Changes in the number, size, and shape of dendritic spines are associated with synaptic plasticity, which underlies cognitive functions such as learning and memory. This plasticity is attributed to reorganization of actin, but the molecular signals that regulate this process are poorly understood. In this study, we show neural Wiskott-Aldrich syndrome protein (N-WASP) regulates the formation of dendritic spines and synapses in hippocampal neurons.

alpha5 integrin signaling regulates the formation of spines and synapses in hippocampal neurons.

The actin-based dynamics of dendritic spines play a key role in synaptic plasticity, which underlies learning and memory. Although it is becoming increasingly clear that modulation of actin is critical for spine dynamics, the upstream molecular signals that regulate the formation and plasticity of spines are poorly understood. In non-neuronal cells, integrins are critical modulators of the actin cytoskeleton, but their function in the nervous system is not well characterized.

8-OH-DPAT attenuates isoproterenol- but not forskolin-stimulated accumulation of cAMP in mediobasal hypothalamus.

Ovariectomized female rats were used to test the possibility that the 5-HT(1A) receptor agonist, 8-hydroxy-2-(di-N-propylamino) tetralin (8-OH-DPAT), inhibits cyclic AMP (cAMP) accumulation in the mediobasal hypothalamus. Tissue slices were incubated with forskolin or with the beta-adrenergic receptor agonist, isoproterenol, to stimulate accumulation of cAMP. Both compounds increased accumulation of cAMP.

Restraint accentuates the effects of 5-HT2 receptor antagonists and a 5-HT1A receptor agonist on lordosis behavior.

The effect of restraint on lordosis behavior was examined in proestrous and ovariectomized, hormone-primed rats. Restraint durations from 5 to 60 min had no effect on lordosis behavior of proestrous rats. There was also no effect of 5 min restraint on lordosis behavior of ovariectomized rats hormonally primed with 10 microg estradiol benzoate and 500 microg progesterone.