UNC-104/KIF1A is a Kinesin-3 motor that transports synaptic vesicles from the cell body towards the synapse by binding to PI(4,5)P2 through its PH domain. The fate of the motor upon reaching the synapse is not known. We found that wild-type UNC-104 is degraded at synaptic regions through the ubiquitin pathway and is not retrogradely transported back to the cell body. As a possible means to regulate the motor, we tested the effect of cargo binding on UNC-104 levels. The unc-104(e1265) allele carries a point mutation (D1497N) in the PI(4,5)P2 binding pocket of the PH domain, resulting in greatly reduced preferential binding to PI(4,5)P2 in vitro and presence of very few motors on pre-synaptic vesicles in vivo. unc-104(e1265) animals have poor locomotion irrespective of in vivo PI(4,5)P2 levels due to reduced anterograde transport. Moreover, they show highly reduced levels of UNC-104 in vivo. To confirm that loss of cargo binding specificity reduces motor levels, we isolated two intragenic suppressors with compensatory mutations within the PH domain. These show partial restoration of in vitro preferential PI(4,5)P2 binding and presence of more motors on pre-synaptic vesicles in vivo. These animals show improved locomotion dependent on in vivo PI(4,5)P2 levels, increased anterograde transport, and partial restoration of UNC-104 protein levels in vivo. For further proof, we mutated a conserved residue in one suppressor background. The PH domain in this triple mutant lacked in vitro PI(4,5)P2 binding specificity, and the animals again showed locomotory defects and reduced motor levels. All allelic variants show increased UNC-104 levels upon blocking the ubiquitin pathway. These data show that inability to bind cargo can target motors for degradation. In view of the observed degradation of the motor in synaptic regions, this further suggests that UNC-104 may get degraded at synapses upon release of cargo.

Dynamic and reciprocal epithelial-mesenchymal interactions are critical for the normal morphogenesis and maintenance of epithelia. Epimorphin has been identified as a unique molecule expressed by mesenchymal cells and myofibroblasts and has putative morphogenetic effects in multiple epithelial tissues, including intestine, skin, mammary gland, lung, gallbladder, and liver. To define the in vivo role of epimorphin, we created epimorphin-null mice by targeted inactivation of the epimorphin gene. Male epimorphin-/- mice are sterile due to abnormal testicular development and impaired spermatogenesis. Intestinal growth is increased in epimorphin-/- mice due to augmented crypt cell proliferation and crypt fission during the neonatal (suckling) period, mediated at least in part by changes in bone morphogenetic protein (Bmp) and Wnt/beta-catenin signaling pathways. Colonic mucosal injury and colitis induced by dextran sodium sulfate (DSS) are ameliorated in epimorphin-/- mice, probably due to the increased proliferative capacity of the epimorphin-/- colon. These in vivo findings support the notion that epimorphin is a key stromal regulator of epithelial cell proliferation and growth in the intestine. In addition, our studies demonstrate a novel and critical role for epimorphin in regulating testicular development and growth as well as spermatogenesis.

Axonal transport of synaptic vesicles (SVs) is a KIF1A/UNC-104 mediated process critical for synapse development and maintenance yet little is known of how SV transport is regulated. Using C. elegans as an in vivo model, we identified SAM-4 as a novel conserved vesicular component regulating SV transport. Processivity, but not velocity, of SV transport was reduced in sam-4 mutants. sam-4 displayed strong genetic interactions with mutations in the cargo binding but not the motor domain of unc-104. Gain-of-function mutations in the unc-104 motor domain, identified in this study, suppress the sam-4 defects by increasing processivity of the SV transport. Genetic analyses suggest that SAM-4, SYD-2/liprin-α and the KIF1A/UNC-104 motor function in the same pathway to regulate SV transport. Our data support a model in which the SV protein SAM-4 regulates the processivity of SV transport.

Premature ovarian failure (POF) results from a number of disorders. The POF model is primarily based on chemotherapeutic injury, and hence is not suitable for assessing the effects of chronic stress on ovarian function. Therefore, improved animal models are required to analyze the effects of chronic stress on ovarian reserve. The feasibility of the chronic unpredictable mild stress (CUMS) method for establishing a model of POF was examined. The depressive behavior exhibited by rats was evaluated with the open field and sucrose preference tests. Vaginal smears were obtained for assessment of the estrous cycle. The ovarian reserve of the animals was evaluated using the estrous cycle, ovarian histology and serum levels of gonadotropin releasing hormone (GnRH), follicle‑stimulating hormone (FSH), estradiol (E2), and anti‑Müllerian hormone (AMH). Compared with the control group, body weight, time spent in the center, horizontal movement, vertical frequency, consumption of sucrose, sucrose preference, number of small follicles from the rats, and serum E2, AMH and GnRH levels were significantly decreased in the CUMS group (all P<0.05). However, the estrous cycle was prolonged significantly (P<0.05) and serum FSH levels were increased significantly (P<0.01). These results suggested that the CUMS model rats exhibited depression‑like behaviors. CUMS may induce psychological stress and decrease ovarian reserve in female rats. Thus, the CUMS model may be used to assess the effects of chronic stress on female reproductive function.

Chemotherapy leads to a loss of fertility and reproductive endocrine function, thereby increasing the risk of premature ovarian failure (POF). Studies have suggested that the transplantation of mesenchymal stem cells could inhibit apoptosis in ovarian granulosa cells and improve follicular development. In the present study, the effects of human umbilical cord mesenchymal stem cell (UCMSC) transplantation on ovarian function after ovarian damage caused by chemotherapy and the mechanism underlying these effects were investigated. POF model rats were obtained by the intraperitoneal injection of cyclophosphamide, and cultured UCMSCs were transplanted by tail vein injection. Serum estrogen, follicle-stimulating hormone, gonadotropin releasing hormone, and anti-Mullerian hormone levels were detected by ELISA. Folliculogenesis was evaluated by histopathological examination. The expression levels of nerve growth factor (NGF), high affinity nerve growth factor receptor (TrkA), follicle-stimulating hormone receptor (FSHR), and caspase-3 were evaluated by western blotting and RT-qPCR. The natural reproductive capacity was assessed by pregnant rate and numbers of embryos. The results indicated that UCMSC transplantation recovered disturbed hormone secretion and folliculogenesis in POF rats. NGF and TrkA levels increased, while FSHR and caspase-3 decreased. The pregnancy rate of POF rats was improved. Therefore, UCMSCs could reduce ovarian failure due to premature senescence caused by chemotherapy, and the NGF/TrkA signaling pathway was involved in the amelioration of POF.

Microcystin-LR (MC-LR) is a potent inhibitor of protein phosphatases 1 and 2A, and has potent hepatotoxicity and tumor promotion activity. Numerous studies on MC-LR toxicity have been conducted in rat hepatocytes, but few studies of the effects of microcystins on human hepatocytes have been done. In this study, HL7702 cells (a human normal liver cell line) were incubated in MC-LR for 24 h. The existence of MC-LR in HL7702 cells was confirmed. Furthermore, PP2A activity and the alteration of PP2A subunits were assessed. The results show that PP2A activity decreased from the concentration of 1 μM MC-LR, showing a concentration-dependent decline, to about 34% at 10 μM MC-LR. This activity undergone opposite change with alternations of phosphorylated Y307-PP2A/C and PP2A/C subunit but showed same change with the alteration of the ratio of methylated L309-PP2A/C to PP2A/C. B55α, a regulatory subunit of PP2A, was slightly increases in cells treated with the highest concentration of MC-LR (10 μM), and colocalized increasedly with rearranged-microtubules after 1 μM MC-LR exposure. However, the proportion of early apoptotic cells did not show any change at various concentration of MC-LR for 24 h. To our knowledge, this is the first report showing MC-LR-induced alteration of PP2A phosphatase in human cultured hepatocytes, and the mechanism of action seems to be similar as described before in vitro. The alteration of PP2A and microtubule seems to be the early event induced by MC-LR exposure.

Three new eudesmane sesquiterpenes, 5 beta-hydroxyilicic acid (1), 5 alpha-hydroxyl-4-epi-ilicic acid methyl ester (2), and 3 alpha-hydroxyilicic acid (3), together with 12 known sesquiterpenes were isolated from the aerial part of Laggera alata. Their structures were elucidated primarily by NMR and mass spectroscopic methods. The structures of 1 and 2 were confirmed by X-ray crystallography.

SUMMARYLittle is known about transcriptional control of neurite branching or presynaptic differentiation, events that occur relatively late in neuronal development. Using the Caenorhabditis elegans mechanosensory circuit as an in vivo model, we show that SAM-10, an ortholog of mammalian single-stranded DNA-binding protein (SSDP), functions cell-autonomously in the nucleus to regulate synaptic differentiation, as well as positioning of, a single neurite branch. PLM mechanosensory neurons in sam-10 mutants exhibit abnormal placement of the neurite branch point, and defective synaptogenesis, characterized by an overextended synaptic varicosity, underdeveloped synaptic morphology and disrupted colocalization of active zone and synaptic vesicles. SAM-10 functions coordinately with Lim domain-binding protein 1 (LDB-1), demonstrated by our observations that: (1) mutations in either gene show similar defects in PLM neurons; and (2) LDB-1 is required for SAM-10 nuclear localization. SAM-10 regulates PLM synaptic differentiation by suppressing transcription of prk-2, which encodes an ortholog of the mammalian Pim kinase family. PRK-2-mediated activities of SAM-10 are specifically involved in PLM synaptic differentiation, but not other sam-10 phenotypes such as neurite branching. Thus, these data reveal a novel transcriptional signaling pathway that regulates neuronal specification of neurite branching and presynaptic differentiation.