Tubular lysosome induction couples animal starvation to healthy aging.

Dietary restriction promotes longevity in several species via autophagy activation. However, changes to lysosomes underlying this effect remain unclear. Here using the nematode Caenorhabditis elegans, we show that the induction of autophagic tubular lysosomes (TLs), which occurs upon dietary restriction or mechanistic target of rapamycin inhibition, is a critical event linking reduced food intake to lifespan extension.

Rbp4-Gal4, a germline driver that activates in meiosis, reveals functions for VCP in spermatid development.

Valosin-containing protein (VCP) is a versatile and ubiquitously expressed AAA+ ATPase that regulates multiple stages of spermatogenesis. While VCP has documented roles in mitotic spermatogonia and meiotic spermatocytes, it is also highly expressed in post-meiotic spermatids, suggesting potential late-stage developmental functions as well. However, tools to assess late-stage activities of pleiotropic spermatogenesis genes such as are lacking.

VCP promotes tTAF-target gene expression and spermatocyte differentiation by downregulating mono-ubiquitylated H2A.

Valosin-containing protein (VCP) binds and extracts ubiquitylated cargo to regulate protein homeostasis. VCP has been studied primarily in aging and disease contexts, but it also affects germline development. However, the precise molecular functions of VCP in the germline, particularly in males, are poorly understood.

A familial natural short sleep mutation promotes healthy aging and extends lifespan in .

Sleep loss typically imposes negative effects on animal health. However, humans with a rare genetic mutation in the gene () present an exception; these individuals sleep less without the usual effects associated with sleep deprivation. Thus, it has been suggested that the mutation activates compensatory mechanisms that allows these individuals to thrive with less sleep.

A familial natural short sleep mutation promotes healthy aging and extends lifespan in .

Sleep loss typically imposes negative effects on animal health. However, humans with a rare genetic mutation in the gene ( ) present an exception; these individuals sleep less without the usual effects associated with sleep deprivation. Thus, it has been suggested that the mutation activates compensatory mechanisms that allows these individuals to thrive with less sleep.

Branching Off: New Insight Into Lysosomes as Tubular Organelles.

Lysosomes are acidic, membrane-bound organelles that play essential roles in cellular quality control, metabolism, and signaling. The lysosomes of a cell are commonly depicted as vesicular organelles. Yet, lysosomes in fact show a high degree of ultrastructural heterogeneity.

Reproductive tradeoffs govern sexually dimorphic tubular lysosome induction in Caenorhabditis elegans.

Sex-specific differences in animal behavior commonly reflect unique reproductive interests. In the nematode Caenorhabditis elegans, hermaphrodites can reproduce without a mate and thus prioritize feeding to satisfy the high energetic costs of reproduction. However, males, which must mate to reproduce, sacrifice feeding to prioritize mate-searching behavior.

A meiotic switch in lysosome activity supports spermatocyte development in young flies but collapses with age.

Gamete development ultimately influences animal fertility. Identifying mechanisms that direct gametogenesis, and how they deteriorate with age, may inform ways to combat infertility. Recently, we found that lysosomes acidify during oocyte maturation in , suggesting that a meiotic switch in lysosome activity promotes female germ-cell health.

Degradative tubular lysosomes link pexophagy to starvation and early aging in .

Organelle-specific autophagy directs degradation of eukaryotic organelles under certain conditions. Like other organelles, peroxisomes are subject to autophagic turnover at lysosomes. However, peroxisome autophagy (pexophagy) has yet to be analyzed in a live-animal system, limiting knowledge on its regulation during an animal's life.

Localization of the ubiquitin ligase Dma1 to the fission yeast contractile ring is modulated by phosphorylation.

The timing of cytokinesis relative to other mitotic events in the fission yeast Schizosaccharomyces pombe is controlled by the septation initiation network (SIN). During a mitotic checkpoint, the SIN is inhibited by the E3 ubiquitin ligase Dma1 to prevent chromosome mis-segregation. Dma1 dynamically localizes to spindle pole bodies (SPBs) and the contractile ring (CR) during mitosis, though its role at the CR is unknown.

Phosphorylation in the intrinsically disordered region of F-BAR protein Imp2 regulates its contractile ring recruitment.

The F-BAR protein Imp2 is an important contributor to cytokinesis in the fission yeast Schizosaccharomyces pombe. Because cell cycle-regulated phosphorylation of the central intrinsically disordered region (IDR) of the Imp2 paralog Cdc15 controls Cdc15 oligomerization state, localization and ability to bind protein partners, we investigated whether Imp2 is similarly phosphoregulated. We found that Imp2 is endogenously phosphorylated on 28 sites within its IDR, with the bulk of phosphorylation being constitutive.

CRISPR/Cas9-engineered Drosophila knock-in models to study VCP diseases.

Mutations in Valosin Containing Protein (VCP) are associated with several degenerative diseases, including multisystem proteinopathy (MSP-1) and amyotrophic lateral sclerosis. However, patients with VCP mutations vary widely in their pathology and clinical penetrance, making it difficult to devise effective treatment strategies. A deeper understanding of how each mutation affects VCP function could enhance the prediction of clinical outcomes and design of personalized treatment options.

SVIP is a molecular determinant of lysosomal dynamic stability, neurodegeneration and lifespan.

Missense mutations in Valosin-Containing Protein (VCP) are linked to diverse degenerative diseases including IBMPFD, amyotrophic lateral sclerosis (ALS), muscular dystrophy and Parkinson's disease. Here, we characterize a VCP-binding co-factor (SVIP) that specifically recruits VCP to lysosomes. SVIP is essential for lysosomal dynamic stability and autophagosomal-lysosomal fusion.

Relief of the Dma1-mediated checkpoint requires Dma1 autoubiquitination and dynamic localization.

Chromosome segregation and cell division are coupled to prevent aneuploidy and cell death. In the fission yeast Schizosaccharomyces pombe, the septation initiation network (SIN) promotes cytokinesis, but upon mitotic checkpoint activation, the SIN is actively inhibited to prevent cytokinesis from occurring before chromosomes have safely segregated. SIN inhibition during the mitotic checkpoint is mediated by the E3 ubiquitin ligase Dma1.

VCP-dependent muscle degeneration is linked to defects in a dynamic tubular lysosomal network in vivo.

Lysosomes are classically viewed as vesicular structures to which cargos are delivered for degradation. Here, we identify a network of dynamic, tubular lysosomes that extends throughout Drosophila muscle, in vivo. Live imaging reveals that autophagosomes merge with tubular lysosomes and that lysosomal membranes undergo extension, retraction, fusion and fission.

Cdk1 promotes cytokinesis in fission yeast through activation of the septation initiation network.

In Schizosaccharomyces pombe, late mitotic events are coordinated with cytokinesis by the septation initiation network (SIN), an essential spindle pole body (SPB)-associated kinase cascade, which controls the formation, maintenance, and constriction of the cytokinetic ring. It is not fully understood how SIN initiation is temporally regulated, but it depends on the activation of the GTPase Spg1, which is inhibited during interphase by the essential bipartite GTPase-activating protein Byr4-Cdc16. Cells are particularly sensitive to the modulation of Byr4, which undergoes cell cycle-dependent phosphorylation presumed to regulate its function.

CK1 is required for a mitotic checkpoint that delays cytokinesis.

Failure to accurately partition genetic material during cell division causes aneuploidy and drives tumorigenesis. Cell-cycle checkpoints safeguard cells from such catastrophes by impeding cell-cycle progression when mistakes arise. FHA-RING E3 ligases, including human RNF8 and CHFR and fission yeast Dma1, relay checkpoint signals by binding phosphorylated proteins via their FHA domains and promoting ubiquitination of downstream targets.

Dnt1 acts as a mitotic inhibitor of the spindle checkpoint protein dma1 in fission yeast.

The Schizosaccharomyces pombe checkpoint protein Dma1 couples mitotic progression with cytokinesis and is important in delaying mitotic exit and cytokinesis when kinetochores are not properly attached to the mitotic spindle. Dma1 is a ubiquitin ligase and potential functional relative of the human tumor suppressor Chfr. Dma1 delays mitotic exit and cytokinesis by ubiquitinating a scaffold protein (Sid4) of the septation initiation network, which, in turn, antagonizes the ability of the Polo-like kinase Plo1 to promote cell division.

Polar opposites: Fine-tuning cytokinesis through SIN asymmetry.

Mitotic exit and cell division must be spatially and temporally integrated to facilitate equal division of genetic material between daughter cells. In the fission yeast, Schizosaccharomyces pombe, a spindle pole body (SPB) localized signaling cascade termed the septation initiation network (SIN) couples mitotic exit with cytokinesis. The SIN is controlled at many levels to ensure that cytokinesis is executed once per cell cycle and only after cells segregate their DNA.

Fission yeast Dma1 requires RING domain dimerization for its ubiquitin ligase activity and mitotic checkpoint function.

In fission yeast (Schizosaccharomyces pombe), the E3 ubiquitin ligase Dma1 delays cytokinesis if chromosomes are not properly attached to the mitotic spindle. Dma1 contains a C-terminal RING domain, and we have found that the Dma1 RING domain forms a stable homodimer. Although the RING domain is required for dimerization, residues in the C-terminal tail are also required to help form or stabilize the dimeric structure because mutation of specific residues in this region disrupts Dma1 dimerization.

VACM-1/cul5 expression in vascular tissue in vivo is induced by water deprivation and its expression in vitro regulates aquaporin-1 concentrations.

VACM-1, a cul5 gene product, when overexpressed in vitro, has an antiproliferative effect. In vivo, VACM-1/cul5 is present in tissues involved in the regulation of water balance. Neither proteins targeted for VACM-1/cul5-specific degradation nor factors that may regulate its expression in those tissues have been studied.

Mutational analysis of VACM-1/cul5 exons in cancer cell lines.

VACM-1, a cul-5 gene product, functions via an E3 ligase complex and when overexpressed, has an antiproliferative effect in many cell types. Overexpression of VACM-/cul5 cDNA mutated at the PKA-specific phosphorylation site at Ser730 reversed this phenotype. These effects are associated with the appearance of larger M(r) species subsequently identified as a Nedd8-modified VACM-1/cul5.

Dma1 ubiquitinates the SIN scaffold, Sid4, to impede the mitotic localization of Plo1 kinase.

Proper cell division requires strict coordination between mitotic exit and cytokinesis. In the event of a mitotic error, cytokinesis must be inhibited to ensure equal partitioning of genetic material. In the fission yeast, Schizosaccharomyces pombe, the checkpoint protein and E3 ubiquitin ligase, Dma1, delays cytokinesis by inhibiting the septation initiation network (SIN) when chromosomes are not attached to the mitotic spindle.

Resveratrol enhances anti-proliferative effect of VACM-1/cul5 in T47D cancer cells.

Vasopressin-activated calcium-mobilizing (VACM-1) protein is a cul-5 gene product that forms complexes with a subclass of ubiquitin E3 ligases involved in proteasomal protein degradation. The expression of VACM-1 cDNA in the T47D breast cancer cell line inhibits growth and decreases phosphorylation of mitogen activated protein kinase. Factors that regulate expression or stability of VACM-1 protein have not been identified, however.