Zhu, Ming et al. (2020) MicroPubl Biol

Jin, Yishi, Chisholm, Andrew D, Zhu, Ming

[MicroPubl Biol, 2020]

VWA8 proteins, named for von Willebrand factor A (VWA) domain containing 8, are conserved from worm to mammals (Whittaker & Hynes, 2002). In mouse, vwa8 gene produces long and short protein isoforms (VWA8a and VWA8b), and in rat livers VWA8a has been shown to localize to the matrix side of inner mitochondrial membrane (Luo et al., 2020). C. elegans vwa-8 is also predicted to produce two major protein isoforms. The short isoform (974 AA) shares identical AA sequences as the long isoform (1804 AA). The two isoforms contain an MTS (mitochondrial targeting sequence) at the N terminus, followed by three AAA ATPase domains, which are associated with diverse cellular activities; and the long isoform contains a VWA domain at the C terminus. To determine the endogenous expression pattern of C. elegans VWA-8, we generated a GFP knock-in allele, ju1799, in which GFP was in-frame fused at the C terminus to label the full-length protein specifically. The endogenous VWA-8::GFP was expressed in mitochondria of hypodermis, intestine and muscle, but was not detectable in neurons (Fig 1A). In hypodermis, VWA-8::GFP was colocalized with MitoTracker Red, a mitochondria marker (Fig 1B).

Zhu, Ming et al. (2020) MicroPubl Biol

Zhu, Ming, Chisholm, Andrew D, Jin, Yishi

[MicroPubl Biol, 2020]

VWA8 proteins, named for von Willebrand factor A (VWA) domain containing 8, are conserved from worm to mammals (Whittaker & Hynes, 2002). In human, two SNPs (rs9566845 and rs9566867) in vwa8 are found to be associated with bipolar disorder with comorbid migraine (Oedegaard et al., 2010). Another SNP (rs9532931) is tentatively associated with a specific sub-group of autism patients (Anney et al., 2010). The C. elegans VWA-8 long isoform shares 38% and 55% amino acid sequence identity and similarity, respectively, with human VWA8 long isoform. We showed that endogenous VWA-8 is expressed in mitochondria of somatic tissues, except neurons (Zhu, Chisholm & Jin, 2020). To determine the function of C. elegans vwa-8, we generated a null allele vwa-8(ju1659) by CRISPR-Cas9. vwa-8(ju1659) mutants are homozygous viable, and indistinguishable from wild type in gross phenotypes such as body size, brood size, growth rate and movement.

Melander RJ et al. (2015) Chem Biol "From worms to targeting virulence factors."

Melander C, Melander RJ

[Chem Biol, 2015]

Rising antibiotic resistance means that alternative antibacterial strategies are sorely needed. In this issue, Zhu etal. (2015) report the use of a Caenorhabditis elegans model to validate the Pseudomonas aeruginosa virulence factor LasB as a potential therapeutic target and to identify a LasB inhibitor with invivo efficacy.

Yeh CY et al. (2021) Dev Cell "A leucine-derived fatty acid unlocks the mTOR to development."

Yeh CY, Lamming DW

[Dev Cell, 2021]

Understanding how nutrient-sensitive signaling pathways regulate development and aging is an active area of research. In this issue of Developmental Cell,Zhu and colleagues (2021) identify a specific monomethylated branched-chain fatty acid that overrides nutrient deprivation signaling and activates mTORC1 in C.elegans and mammalian cells.

Molinie N et al. (2016) Dev Cell "WASP and WAVE Team Up at the Leading Edge."

Molinie N, Gautreau A

[Dev Cell, 2016]

Arp2/3-dependent branched actin networks drive membrane protrusions, with WAVE being recognized as the critical Arp2/3 activator in this process. In this issue of Developmental Cell, Zhu etal. (2016) demonstrate that WASP, an Arp2/3 activator mostly involved in endocytosis, collaborates with WAVE to promote migration of neuroblasts in Caenorhabditis elegans.

Hodgkin J (2002) Genes Dev "The remarkable ubiquity of DM domain factors as regulators of sexual phenotype: ancestry or aptitude?"

Hodgkin J

[Genes Dev, 2002]

The CM domain is a cysteine-rich DNA-binding motif first recognized in proteins encoded by the Drosophila set determination gene doublesex (Erdman and Burtis 1993; Zhu et al. 2000). As the name doublesex (dsx) suggests, this gene has functions in both sexes: Its transcripts undergo sex-specific alternative splicing, so that it can encode either a male-specific isoform, DSX(M), or a female-specific isoform, DSX(F) (Baker and Wolfner 1988; Burtis and Baker 1989). These proteins have the same N-terminal DNA-binding domain, but different C termini that confer different regulatory properties on the two forms. The expression of DSX(M) directs male development, and the expression of DSX(F) directs female development, throughout most of the somatic tissues of the fruit fly.

Sagulo, Seth et al. (2015) International Worm Meeting "Investigating the Role of Host Cell Factor 1 and Ribosomal S6 Kinase in Regulation of Longevity."

Sagulo, Seth, Lee, Siu Sylvia

[International Worm Meeting, 2015]

The Lee lab has identified Host Cell Factor 1 (HCF-1) as a transcriptional corepressor of DAF-16/FOXO, a major downstream effector of the highly conserved insulin/insulin-like (IIS) signaling pathway. C. elegans that are mutant in hcf-1 have an extended lifespan that is dependent on daf-16. Host Cell Factor 1 is a nuclear expressed protein that acts as a scaffolding protein as it does not have a clear DNA binding domain. Thus it likely plays a role in various protein-protein interactions, some of which may be important for regulating lifespan. Since many of the proteins that interact with HCF-1 have not yet been identified immunoprecipitation-mass spectrometry (IP-MS) was performed in collaboration with the Ruvkun lab and Ming Zhu, Meng-Qiu Dong of the Dong lab. This was done using a strain of C. elegans expressing HCF-1 tagged with GFP. Several chromatin related factors including the histone deacetylase SIN-3 which has been previously shown to interact with HCF-1 in addition to many metabolism proteins were found to interact with HCF-1. Surprisingly, the downstream kinase of the highly conserved target of rapamycin (TOR) pathway, ribosomal S6 kinase (RSKS-1/S6K1) was also identified which suggests it may play a role in the regulation of HCF-1 through phosphorylation. Interestingly, previously published data shows that rsks-1 mutants have an extended lifespan that is dependent on daf-16 which is similar to hcf-1 mutants. To support the IP-MS data, the genetic relationship of rsks-1 and hcf-1 was tested. The rsks-1;hcf-1 double mutant does not show an additive extension of lifespan compared to either of the rsks-1 or hcf-1 single mutants providing evidence that HCF-1 and RSKS-1 may be working through the same pathway to regulate longevity in C. elegans. Since HCF-1 and RSKS-1 are both highly conserved proteins understanding the novel biochemical and genetic connection between them will be relevant to aging in mammals.

He XY et al. (1998) J Biol Chem "A human brain L-3-hydroxyacyl-coenzyme A dehydrogenase is identical to an amyloid beta-peptide-binding protein involved in Alzheimer's disease."

He XY, Schulz H, Yang SY

[J Biol Chem, 1998]

A novel L-3-hydroxyacyl-CoA dehydrogenase from human brain has been cloned, expressed, purified, and characterized. This enzyme is a homotetramer with a molecular mass of 108 kDa. Its subunit consists of 261 amino acid residues and has structural features characteristic of short chain dehydrogenases. It was found that the amino acid sequence of this human brain enzyme is identical to that of an endoplasmic reticulum amyloid beta-peptide-binding protein (ERAB), which mediates neurotoxicity in Alzheimer's disease (Yan, S. D., Fu, J., Soto, C., Chen, X., Zhu, H., Al-Mohanna, F., Collison, K., Zhu, A., Stern, E., Saido, T., Tohyama, M., Ogawa, S., Roher, A., and Stern, D. (1997) Nature 389, 689-695). The purification of human brain short chain L-3-hydroxyacyl-CoA dehydrogenase made it possible to characterize the structural and catalytic properties of ERAB. This NAD+-dependent dehydrogenase catalyzes the reversible oxidation of L-3-hydroxyacyl-CoAs to form 3-ketoacyl-CoAs, but it does not act on the D-isomers. The catalytic rate constant of the purified enzyme was estimated to be 37 s-1 with apparent Km values of 89 and 20 microM for acetoacetyl-CoA and NADH, respectively. The activity ratio of this enzyme for substrates with chain lengths of C4, C8, and C16 was approximately 1:2:2. The human short chain L-3-hydroxyacyl-CoA dehydrogenase gene is organized into six exons and five introns and maps to chromosome Xp11.2. The amino-terminal NAD-binding region of the dehydrogenase is encoded by the first three exons, whereas the other exons code for the carboxyl-terminal substrate-binding region harboring putative catalytic residues. The results of this study lead to the conclusion that ERAB involved in neuronal dysfunction is encoded by the human short chain L-3-hydroxyacyl-CoA dehydrogenase gene.

Shih-Chieh Chien et al. (2007) International Worm Meeting "The MIG-15 kinase functions in canonical Wnt signaling."

Gian Garriga, Shih-Chieh Chien

[International Worm Meeting, 2007]

MIG-15 is an ortholog of Nck-interacting kinase (NIK) in mice and Misshapen in Drosophila. All three molecules belong to the Ste20 kinase superfamily. We have characterized the cell migration defects of mig-15 mutants, confirming and extending some of the observations made by Zhu and Hedgecock (1997)1. During embryogenesis, the HSN neurons migrate anteriorly, and we found that the HSNs often stopped prematurely in mig-15 mutants. In L1 animals, the descendents of the QR neuroblast migrate anteriorly, while QL descendents migrate posteriorly. In mig-15 mutants, the QR descendents stopped prematurely while the QL descendents migrated anteriorly in the wrong direction. These cell migration defects are similar to those found in Wnt mutants, raising the intriguing possibility that mig-15 may function in Wnt signaling. To test this hypothesis, we asked whether expression of mab-5 in QL was affected by mig-15 mutations. The Wnt EGL-20, acting through a canonical Wnt signaling pathway, turns on mab-5 expression. MAB-5, a Hox transcription factor, then specifies the posterior migration program of QL. Using a mab-5::lacZ reporter, we found that mab-5 expression was greatly attenuated in mig-15 mutants, consistent with MIG-15 playing an important role in Wnt signaling. We also found that a gain-of-function mab-5 mutation suppressed the QL defect of mig-15 mutants, providing genetic evidence that mig-15 acts upstream of mab-5 in the Wnt signaling pathway. Drosophila Misshapen has been shown to function in the Planar Cell Polarity, which is mediated by Frizzled receptors and Dishevelled, components that also function in Wnt signaling. Yet the role of MIG-15 in QL migration is novel since its homologs have not been implicated in canonical Wnt signaling. We will define where MIG-15 acts in the canonical Wnt signaling pathway and whether it acts directly in the process, or indirectly by regulating one of the Wnt pathway components. 1: Zhu, X. & Hedgecock, E.M. (1997). International C. elegans Meeting.

Meng, Jun et al. (2017) International Worm Meeting "Myrf ER-bound transcription factors drive C. elegans synaptic plasticity via cleavage-dependent nuclear translocation."

Jin, Xia, Tao, Huaping, Dong, Meng-Qiu, Qi, Yingchuan, Witvliet, Daniel, Ma, Xiaoxia, Michell, James, Jin, Yishi, Zhu, Ming, Meng, Jun, Zhen, Mei

[International Worm Meeting, 2017]

One of the enigmatic characteristics of the developing nervous system is its ability to remodel and refine neuronal connections during its transition into a functional, mature nervous system. A striking and informative example of synaptic refinement occurs during the development of the C. elegans nervous system, in which the GABAergic dorsal D (DD) neuron reverses its axonal and dendritic domains without overt changes in morphology. The synaptic rewiring allows DD neurons to acquire new connectivity and be integrated into a more mature motor circuit. This dramatic process offers a powerful model in which we can identify genes that are essential for the developmental plasticity of neurons. We have identified myrf-1, a homologue of Myrf (Myelin regulatory factor) family transcription factors, as a key regulator of synaptic rewiring in C. elegans. MYRF-1 and its paralog MYRF-2 are functionally redundant specifically in synaptic rewiring. They co-exist in the same protein complex, and act cooperatively to regulate synaptic rewiring. We find that the MYRF proteins localize to the endoplasmic reticulum membrane, and that they are cleaved into active N-terminal fragments, which then translocate into the nucleus to drive synaptic rewiring. Over-expression of active forms of MYRF is sufficient to accelerate synaptic rewiring. MYRF-1 and MYRF-2 are the first genes identified to be indispensable for promoting synaptic rewiring in C. elegans. These findings reveal a novel molecular mechanism underlying synaptic rewiring and developmental circuit plasticity.