P5A ATPase controls ER translocation of Wnt in neuronal migration.

The Wnt family contains conserved secretory proteins required for developmental patterning and tissue homeostasis. However, how Wnt is targeted to the endoplasmic reticulum (ER) for processing and secretion remains poorly understood. Here, we report that CATP-8/P5A ATPase directs neuronal migration non-cell autonomously in Caenorhabditis elegans by regulating EGL-20/Wnt biogenesis. CATP-8 likely functions as a translocase to translocate nascent EGL-20/Wnt polypeptide into the ER by interacting with the highly hydrophobic core region of EGL-20 signal sequence. Such regulation of Wnt biogenesis by P5A ATPase is common in C. elegans and conserved in human cells. These findings describe the physiological roles of P5A ATPase in neural development and identify Wnt proteins as direct substrates of P5A ATPase for ER translocation.

In vivo imaging of a PVD neuron in Caenorhabditis elegans.

The nematode Caenorhabditis elegans nociceptive PVD neurons have highly ordered dendritic branches, making this an ideal model to study the development and organization of dendrites. A ser-2-promoter-driven GFP reporter line wyIs592[ser-2prom-3p::myr-GFP] provides a comprehensive visualization of PVD anatomy. Here, we describe the detailed procedures for imaging a PVD neuron using wyIs592 at late L4 larval stage in vivo by confocal microscopy. This protocol can also be applied to imaging other cells in C. elegans. For complete details on the use and execution of this protocol, please refer to Feng et al. (2020).

CATP-8/P5A ATPase Regulates ER Processing of the DMA-1 Receptor for Dendritic Branching.

Dendrite morphogenesis is essential for a neuron to establish its receptive field and is, thus, the anatomical basis for the proper functioning of the nervous system. The molecular mechanisms governing dendrite branching are not fully understood. Using the multi-dendritic PVD neuron in the nematode Caenorhabditis elegans, we identify CATP-8/P5A ATPase as a key regulator of dendrite branching that controls the translocation of the DMA-1 receptor to the endoplasmic reticulum (ER). The specific signal peptide of DMA-1 and the ATPase activity of CATP-8 are essential for this process. Our results reveal that P5A ATPase may regulate protein translocation in the ER.

Crystal structure of a bacterial homolog to human lysosomal transporter, spinster.

Lysosomes break down various biomolecules and spinster is one of the major efflux carriers removing degradation products from lysosomal lumen to keep it in healthy size and proper function. Although it is well established that a dysfunctional spinster will cause enlarged lysosomes and in turn lead to developmental defects and abnormal behavior in animals, little was known about the transportation mechanism and substrate specificity of spinster. Here, we report a crystal structure of spinster homolog from Hyphomonas neptunium, HnSPNS, in its inward-facing conformation with and without substrate bound. HnSPNS is crystallized in a monomer and a substrate-binding cavity was formed in the center of its transmembrane helices. A blob of electron density corresponding to its substrate was found in the cavity near a conserved residue, R42, which is locked in position by the interactions with conserved residues E129 and R122. Our results suggest that human spinster serves as a transporter translocating negatively-charged lipophilic small molecules and E129 might serve as a switch to control the conformational change via its protonation-deprotonation cycle.

A putative soybean GmsSOS1 confers enhanced salt tolerance to transgenic Arabidopsis sos1-1 mutant.

The cDNA of GmsSOS1, a putative plasma membrane Na(+)/H(+) antiporter gene isolated from Glycine max, Glycine soja, and their hybrid, was constructed into plant expression vector pCAMBIA 1300 and then transformed with Agrobacterium tumefaciens under the control of CaMV 35S promoter to Arabidopsis thaliana wild-type (WT) and mutant (atsos1-1) plants. By hygromycin resistance detection and PCR analysis, transgenic plants (WT35S:GmsSOS1 and atsos1-1 35S:GmsSOS1) were obtained. Seed germination, seedling growth, and Na(+) contents in roots and shoots were analytically compared among WT, atsos1-1 mutant, and their transgenic lines under salt stress. The results showed that when GmsSOS1 was integrated into the genome of A. thaliana, the inhibitions of salt stress on seed germination and seedling growth were all significantly improved, and enhanced salt tolerance was displayed, which may be attributed to the decrease of Na(+) absorption in roots and transportation in shoots of the transgenic lines, especially for that of atsos1-1 mutant.