Biology subjects

Petersen, E. N.

Publications and source records attributed to Petersen, E. N..

4 recordsLinked to original sources

bioRxiv2025

The dramatic impact of the PER-DBT interaction on circadian timekeeping andtemperature compensation

Circadian timekeeping is orchestrated by multiple clock proteins, but mechanistic understanding is limited. AlphaFold predicts novel interactions between two helical domains of the Drosophila PERIOD (PER) protein and its major kinase Doubletime (DBT). These PER domains, SYQ and LT, are conserved with mammals and are predicted to interact identically with the DBT ortholog casein kinase 1 (CK1). SYQ and LT mutations designed to disrupt this interface result in severe period and temperature-sensitive fly phenotypes, and two LT mutations cause unprecedented free-running periods [≥] 44 hours and temperature-sensitive changes of [~]20 hours. Further characterization of a LT mutant strain shows a severe reduction in both PER phosphorylation and PER degradation. A human PER equivalent of the same LT mutation is a much less efficient in vitro substrate for CK1-mediated phosphorylation. These observations indicate that this conserved PER-DBT interaction is critical for PER phosphorylation, circadian timing and its enigmatic temperature compensation phenomena.

molecular biology↗

bioRxiv2019

Measuring anesthetic resistance in Drosophila by VAAPR

Volatile anesthetics are compounds which are commonly used to induce a reversable loss of consciousness (LOC) in animals. The molecular mechanism of how anesthetics induce LOC is largely unknown. However, observations have been made which show that there are genetically-encoded traits which influence the effective concentration of anesthetics in the inducement of LOC. Despite this long-term observation, little progress has been made in identifying genes involved in anesthetic sensitivity. One reason for this is that many techniques to test anesthetic sensitivity are technically challenging and are inhibitory for high-throughput studies. Here we introduce a technique for testing volatiles and aerosols with positional recording (VAAPR), a method which allows for high-throughput testing of the effect of anesthetics and other aerosolized drugs using Drosophila. Using VAAPR we show that the enzyme phospholipase D (PLD) significantly shifts the concentration of diethyl ether, chloroform, and isoflurane needed to induce LOC in Drosophila. We also show that PLD is required for a paradoxical hyperactivity phenotype. We expect that this technique will allow for additional genes to be found which control anesthetic sensitivity as well as other behavioral phenotypes.

pharmacology and toxicology↗

bioRxiv2019

Phospholipase D Transduces Force to TREK-1 Channels in a Biological Membrane

Rapid conversion of force into a biological signal enables living cells to respond to mechanical forces in their environment. The force is believed to initially affect the plasma membrane and then alter the behavior of membrane proteins. Phospholipase D2 (PLD2) is a mechanosensitive enzyme that is regulated by a structured membrane-lipid site comprised of cholesterol and saturated ganglioside (GM1). Here we show stretch activation of TWIK-related K+ channel (TREK-1) is mechanically evoked by PLD2 and spatial patterning involving ordered GM1 and 4,5- bisphosphate (PIP2) clusters. First, mechanical force deforms the ordered lipids, which lowers membrane cholesterol, disrupts the interaction of PLD2 with the GM1 lipids, and allows a complex of TREK-1 and PLD2 to associate with PIP2 clusters. The association with PIP2 activates the enzyme, which produces the second messenger phosphatidic acid (PA) that gates the channel. Co-expression of catalytically inactive PLD2 inhibits TREK-1 stretch currents in a biological membrane. Cellular uptake of cholesterol inhibits TREK-1 currents in culture and depletion of cholesterol from astrocytes releases TREK-1 from GM1 lipids in mouse brain. Depletion of the PLD2 ortholog in flies results in hypersensitivity to mechanical force. We conclude PLD2 mechanosensitivity combines with TREK-1 ion permeability to elicit a mechanically evoked response. SummaryShear thinning activates TREK-1 through a second messenger.

neuroscience↗

bioRxiv2018

Studies on the mechanism of general anesthesia

Inhaled anesthetics are a chemically diverse collection of hydrophobic molecules that robustly activate TWIK related K+ channels (TREK-1) and reversibly induce loss of consciousness. For a hundred years anesthetics were speculated to target cellular membranes, yet no plausible mechanism emerged to explain a membrane effect on ion channels. Here we show that inhaled anesthetics (chloroform and isoflurane) activate TREK-1 through disruption of palmitate-mediated localization of phospholipase D2 (PLD2) to lipid rafts and subsequent production of signaling lipid phosphatidic acid (PA). Catalytically dead PLD2 robustly blocks anesthetic TREK-1 currents in cell patch-clamp. Localization of PLD2 renders the anesthetic-insensitive TRAAK channel sensitive. General anesthetics chloroform, isoflurane, diethyl ether, xenon, and propofol disrupt lipid rafts and activate PLD2. In the whole brain of flies, anesthesia disrupts rafts and PLDnull flies resist anesthesia. Our results establish a membrane mediated target of inhaled anesthesia and suggest PA helps set anesthetic sensitivity in vivo.

neuroscience↗