July 2016 | Volume 214, No. 1
People & Ideas
- Lysosome acidification by photoactivated nanoparticles restores autophagy under lipotoxicity
Lipotoxicity is frequently associated with alkalinization of lysosomes and impaired autophagic flux but the relationship between the two is unclear. Trudeau et al. show that autophagic flux can be restored in β islet cells chronically exposed to fatty acids by re-acidification of lysosomes with photoactivatable nanoparticles.
- Exosomes mediate cell contact–independent ephrin-Eph signaling during axon guidance
Ephs interact with ESCRT complex components and are released via extracellular vesicles or exosomes. EphB2 released via exosomes mediates a novel cell contact–independent mode of ephrin-Eph signaling that contributes to axon guidance in cell–cell repulsion processes.
- The Sam68 nuclear body is composed of two RNase-sensitive substructures joined by the adaptor HNRNPL
Some nuclear bodies are formed with an architectural RNA (arcRNA) as the structural core. Here, Mannen et al. screened for new nuclear bodies built on unidentified arcRNAs and found that the Sam68 nuclear body (SNB) is composed of two distinct RNase-sensitive substructures. HNRNPL acts as the adaptor to combine the two substructures, thus forming the full SNB.
- SEC16A is a RAB10 effector required for insulin-stimulated GLUT4 trafficking in adipocytes
Sec16A is known to be required for COPII vesicle formation from the ER. Here, Bruno et al. show that, independent of its role at the ER, Sec16A is a RAB10 effector involved in the insulin-stimulated formation of specialized transport vesicles that ferry the GLUT4 glucose transporter to the plasma membrane of adipocytes.
- Phosphatidylserine transport by Ups2–Mdm35 in respiration-active mitochondria
Phosphatidylethanolamine, an essential phospholipid for mitochondrial functions, is synthesized at the mitochondrial inner membrane. Miyata et al. demonstrate that Ups2–Mdm35, a protein complex in the mitochondrial intermembrane space, mediates phosphatidylserine transport for phosphatidylethanolamine synthesis in respiration-active mitochondria of Saccharomyces cerevisiae.
- A Presenilin-2–ARF4 trafficking axis modulates Notch signaling during epidermal differentiation
Ciliogenesis in differentiating epidermal cells correlates with activation of Notch signaling, which requires Presenilin-2 targeting to basal bodies/cilia. Ezratty et al. show that the GTPase ARF4 regulates Presenilin-2 localization and subsequent Notch-dependent differentiation, suggesting that polarized exocytosis to basal bodies spatially regulates Notch signaling during skin development.
- Facilitation of axon regeneration by enhancing mitochondrial transport and rescuing energy deficits
Zhou et al. show that reduced mitochondrial motility and energy deficits in injured axons are intrinsic mechanisms contributing to regeneration failure in mature neurons.