Septin 7 is a centrosomal protein that ensures S phase entry and microtubule nucleation by maintaining the abundance of p150glued.

Septins play important roles in regulating development and differentiation. Septin 7 (SEPT7) is a crucial component in orchestrating the septin core complex into highly ordered filamentous structures. Here, we showed that genetic depletion of SEPT7 or treatment with forchlorfenuron (FCF; a compound known to affect septin filament assembly) led to reduced the S phase entry in cell models and zebrafish embryos. In addition to colocalizing with actin filaments, SEPT7 resided in the centrosome, and SEPT7 depletion led to aberrant mitotic spindle pole formation. This mitotic defect was rescued in SEPT7-deficient cells by wild-type SEPT7, suggesting that SEPT7 maintained mitotic spindle poles. In addition, we observed disorganized microtubule nucleation and reduced cell migration with SEPT7 depletion. Furthermore, SEPT7 formed a complex with and maintained the abundance of p150glued , the component of centriole subdistal appendages. Depletion of p150glued resulted in a phenotype reminiscent of SEPT7-deficient cells, and overexpression of p150glued reversed the defective phenotypes. Thus, SEPT7 is a centrosomal protein that maintains proper cell proliferation and microtubule array formation via maintaining the abundance of p150glued .

LRWD1 Regulates Microtubule Nucleation and Proper Cell Cycle Progression in the Human Testicular Embryonic Carcinoma Cells.

Leucine-rich repeats and WD repeat domain containing protein 1 (LRWD1) is a testis-specific protein that mainly expressed in the sperm neck where centrosome is located. By using microarray analysis, LRWD1 is identified as a putative gene that involved in spermatogenesis. However, its role in human male germ cell development has not been extensively studied. When checking in the semen of patients with asthenozoospermia, teratozoospermia, and asthenoteratozoospermia, the level of LRWD1 in the sperm neck was significantly reduced with a defective neck or tail. When checking the sub-cellular localization of LRWD1 in the cells, we found that LRWD1 resided in the centrosome and its centrosomal residency was independent of microtubule transportation in NT2/D1, the human testicular embryonic carcinoma, cell line. Depletion of LRWD1 did not induce centrosome re-duplication but inhibited microtubule nucleation. In addition, the G1 arrest were observed in LRWD1 deficient NT2/D1 cells. Upon LRWD1 depletion, the levels of cyclin E, A, and phosphorylated CDK2, were reduced. Overexpression of LRWD1 promoted cell proliferation in NT2/D1, HeLa, and 239T cell lines. In addition, we also observed that autophagy was activated in LRWD1 deficient cells and inhibition of autophagy by chloroquine or bafilomycin A1 promoted cell death when LRWD1 was depleted. Thus, we found a novel function of LRWD1 in controlling microtubule nucleation and cell cycle progression in the human testicular embryonic carcinoma cells. J. Cell. Biochem. 119: 314-326, 2018. © 2017 Wiley Periodicals, Inc.

Lysosomal activity maintains glycolysis and cyclin E1 expression by mediating Ad4BP/SF-1 stability for proper steroidogenic cell growth.

The development and differentiation of steroidogenic organs are controlled by Ad4BP/SF-1 (adrenal 4 binding protein/steroidogenic factor 1). Besides, lysosomal activity is required for steroidogenesis and also enables adrenocortical cell to survive during stress. However, the role of lysosomal activity on steroidogenic cell growth is as yet unknown. Here, we showed that lysosomal activity maintained Ad4BP/SF-1 protein stability for proper steroidogenic cell growth. Treatment of cells with lysosomal inhibitors reduced steroidogenic cell growth in vitro. Suppression of autophagy did not affect cell growth indicating that autophagy was dispensable for steroidogenic cell growth. When lysosomal activity was inhibited, the protein stability of Ad4BP/SF-1 was reduced leading to reduced S phase entry. Interestingly, treatment of cells with lysosomal inhibitors reduced glycolytic gene expression and supplying the cells with pyruvate alleviated the growth defect. ChIP-sequence/ChIP studies indicated that Ad4BP/SF-1 binds to the upstream region of Ccne1 (cyclin E1) gene during G1/S phase. In addition, treatment of zebrafish embryo with lysosomal inhibitor reduced the levels of the interrenal (adrenal) gland markers. Thus lysosomal activity maintains steroidogenic cell growth via stabilizing Ad4BP/SF-1 protein.

Primary Cilium-Regulated EG-VEGF Signaling Facilitates Trophoblast Invasion.

Trophoblast invasion is an important event in embryo implantation and placental development. During these processes, endocrine gland-derived vascular endothelial growth factor (EG-VEGF) is the key regulator mediating the crosstalk at the feto-maternal interface. The primary cilium is a cellular antenna receiving environmental signals and is crucial for proper development. However, little is known regarding the role of the primary cilium in early human pregnancy. Here, we demonstrate that EG-VEGF regulates trophoblast cell invasion via primary cilia. We found that EG-VEGF activated ERK1/2 signaling and subsequent upregulation of MMP2 and MMP9, thereby facilitating cell invasion in human trophoblast HTR-8/SVneo cells. Inhibition of ERK1/2 alleviated the expression of MMPs and trophoblast cell invasion after EG-VEGF treatment. In addition, primary cilia were observed in all the trophoblast cell lines tested and, more importantly, in human first-trimester placental tissue. The receptor of EG-VEGF, PROKR1, was detected in primary cilia. Depletion of IFT88, the intraflagellar transporter required for ciliogenesis, inhibited primary cilium growth, thereby ameliorating ERK1/2 activation, MMP upregulation, and trophoblast cell invasion promoted by EG-VEGF. These findings demonstrate a novel function of primary cilia in controlling EG-VEGF-regulated trophoblast invasion and reveal the underlying molecular mechanism. J. Cell. Physiol. 232: 1467-1477, 2017. © 2016 Wiley Periodicals, Inc.

Cell Cycle-Dependent Localization of Dynactin Subunit p150 glued at Centrosome.

p150(glued) is the largest subunit of dynactin protein complex, through which cargo vesicles link to the microtubule minus-end directed motor protein dynein. In addition, p150(glued) also locates in the mother centriole where it organizes the subdistal appendage. The components of appendage are dynamically regulated throughout the cell cycle stages, but it is still unclear whether the centrosomal residency of p150(glued) correlated with cell cycle progression. Here we found that p150(glued) was located in the mother centriole during G1/S stage and its centrosomal residency was independent of microtubule transportation. However, the centrosomal p150(glued) became blurred at G2/M phase and this event was not regulated by its phosphorylation. Entering into mitosis, p150(glued) was robustly enriched in the mitotic spindle nearby the spindle poles but not in the centrosome. During serum starvation (G0 stage), p150(glued) appeared at the base of primary cilium and its depletion attenuated starvation-induced primary cilium formation. We also checked its role in the maintenance of centrosome homeostasis and configuration, and found depletion of p150(glued) did not induce centrosome amplification or splitting but inhibited U2OS cell growth. G1 arrest and reduced EdU incorporation were observed in p150(glued) deficient U2OS cells. In addition, cyclin E was downregulated following p150(glued) depletion. The p53/p21 signaling was activated indicating that CDKs were inactivated. The reduced cell growth was ameliorated in the p150(glued) depleted cells when treated with p53 inhibitor. Thus, we have identified the centrosomal targeting of p150(glued) in distinct cell cycle stage and uncovered its role in controlling G1/S transition.