Science - 31 January 2020

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RESEARCH | IN OTHER JOURNALS

physiological relevance has not
been explored. Yan et al. studied
two different experimental
mouse tumor models and
found that MAIT cells promoted
lung metastasis by quashing
natural killer cell activity. The
researchers could block this
effect and reduce metastasis
by using inhibitory antibodies
against MR1. Targeting the MAIT
cell–MR1 axis may represent an
emerging strategy for cancer
immunotherapy. —PNK
Cancer Discov. 10 , 124 (2020).

CELL BIOLOGY

The cellular architecture

of ERAD

Endoplasmic reticulum (ER)–
associated degradation (ERAD)
is an evolutionarily conserved
quality control mechanism
whereby misfolded proteins
are removed from the ER and
degraded in the cytosol by the
ubiquitin-proteasome system.
Many ERAD-mediating proteins
have been identified, but their
spatial organization within the
cell is less well established.
Albert et al. used in situ cryo–
electron tomography to image
the native molecular land-
scape within Chlamydomonas
cells. They found that ERAD
proteins concentrated within

~200-nanometer cytosolic foci

that contacted the ER mem-

brane away from the ER-Golgi

interface. The ribosome-exclud-

ing ERAD microcompartments

consisted of a core of clustered

proteasomes surrounded by

Cdc48. Within these clusters,

active proteasomes appeared to

engage directly with substrates

at the ER membrane, a func-

tion thought to be performed

by Cdc48. In live-cell imaging

experiments, the proteasome

clusters were seen to form

dynamically, possibly by liquid-

liquid phase separation. This

dynamic, but well-defined,

architecture of ERAD machinery

likely contributes to efficient

protein quality control. —SMH

Proc. Natl. Acad. Sci. U.S.A. 117 , 1069

(2020).

NEUROSCIENCE

Fast and slow recycling of

synaptic vesicles

The function of microtubules

and filamentous actin in mature

synapses is not fully under-

stood. Using confocal and

stimulated emission depletion

microscopy on a giant audi-

tory synapse of the rat nervous

system, termed the calyx of

Held, Babu et al. found that

microtubules extended into

terminal swellings and were par-

tially colocalized with synaptic

vesicles. Depolymerization of

microtubules in calyceal termi-

nals prolonged the recovery of

excitatory postsynaptic currents

from short-term depression,

whereas fast recovery from

short-term depression was

prolonged by depolymeriza-

tion of filamentous actin. These

results reveal distinct contribu-

tions of filamentous actin and

microtubules to synaptic neuro-

transmission and indicate that

these cytoskeletal elements

independently contribute to dif-

ferent aspects of the recycling

of synaptic vesicles. —PRS

J. Neurosci. 40 , 131 (2020).

QUANTUM GASES

Probing a quantum

emulsion

Ultracold atomic gases with

strongly repulsive interactions

can be a useful model system

for studying the emergence

of itinerant ferromagnetism.

However, the same atoms

that can order magnetically

are also prone to pairing into

loosely bound molecules. If

an atomic system is suddenly

placed in a strongly interact-

ing regime, both processes

occur and an inhomogeneous,

phase-separated state con-

sisting of unpaired and paired

atoms can form. Scazza et al.

studied this state with a variety

of probes. The data were con-

sistent with the formation of a

quantum emulsion consisting

of polarized domains coexisting

with paired atoms. The state

was stabilized by low tempera-

tures and strong interactions.

—JS

Phys. Rev. A 101 , 013603 (2020).

MEMBRANE PROTEINS

Simulating deformation

Biological membranes are

jam-packed with proteins and

enzymes that exert forces, both

static and dynamic, on their

adjacent lipids and can cause

local and global changes in mem-

brane curvature. Zhou et al. used

large-scale molecular dynam-

ics simulations to understand

how the membranes around

a small-molecule transporter

deform as the protein undergoes

motions coupled to transport. By

comparing different states of the

transporter, the authors found

that the lipids move with the

transport domains, causing local

deformations of ~10 angstroms

in an area of ~1000 square

angstroms at a cost of 6 to 7

kilocalories per mole. —MAF

eLife 8 , e50576 (2019).

FAT M E TA B O L I S M

Signals from lipid hydrolysis

A

n exploration of how lipolysis is coupled

to mitochondrial changes that increase

oxidative capacity may reveal how a

Mediterranean diet is beneficial. Najt

et al. found that monounsaturated

fatty acids (MUFAs) released by lipolysis

bound to the protein perilipin 5, which car-

ried them to the nucleus. MUFAs also bound

to the deacetylase sirtuin 1 (SIRT1), which

is implicated in the health span–improving

effects of caloric restriction. MUFA binding

increased SIRT1 activity toward certain sub-

strates. Foods like nuts, avocados, and olive

oil all provide MUFAs in the diet, and these

effects could in part underlie their beneficial

properties. —LBR

Mol. Cell 10.1016/j.molcel.2019.12.003 (2020).

Eating a selection of foods that are high in

monounsaturated fatty acids is beneficial for health.

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PHOTO: PROSTOCK-STUDIO/ALAMY STOCK PHOTO

Published by AAAS