Oriented cell division is one mechanism progenitor cells use during development and to maintain tissue homeostasis. Common to most cell types is the asymmetric establishment and regulation of cortical NuMA-dynein complexes that position the mitotic spindle. Here, we discover that HMMR acts at centrosomes in a PLK1-dependent pathway that locates active Ran and modulates the cortical localization of NuMA-dynein complexes to correct mispositioned spindles. This pathway was discovered through the creation and analysis of Hmmr-knockout mice, which suffer neonatal lethality with defective neural development and pleiotropic phenotypes in multiple tissues. HMMR over-expression in immortalized cancer cells induces phenotypes consistent with an increase in active Ran including defects in spindle orientation. These data identify an essential role for HMMR in the PLK1-dependent regulatory pathway that orients progenitor cell division and supports neural development.

Cell-cycle progression and the acquisition of a migratory phenotype are hallmarks of human carcinoma cells that are perceived as independent processes but may be interconnected by molecular pathways that control microtubule nucleation at centrosomes. Here, cell-cycle progression dramatically impacts the engraftment kinetics of 4T1-luciferase2 breast cancer cells in immunocompetent BALB/c or immunocompromised NOD-SCID gamma (NSG) mice. Multiparameter imaging of wound closure assays was used to track cell-cycle progression, cell migration, and associated phenotypes in epithelial cells or carcinoma cells expressing a fluorescence ubiquitin cell-cycle indicator. Cell migration occurred with an elevated velocity and directionality during the S-G-phase of the cell cycle, and cells in this phase possess front-polarized centrosomes with augmented microtubule nucleation capacity. Inhibition of Aurora kinase-A (AURKA/Aurora-A) dampens these phenotypes without altering cell-cycle progression. During G-phase, the level of phosphorylated Aurora-A at centrosomes is reduced in hyaluronan-mediated motility receptor (HMMR)-silenced cells as is the nuclear transport of TPX2, an Aurora-A-activating protein. TPX2 nuclear transport depends upon HMMR-T703, which releases TPX2 from a complex with importin-α (KPNA2) at the nuclear envelope. Finally, the abundance of phosphorylated HMMR-T703, a substrate for Aurora-A, predicts breast cancer-specific survival and relapse-free survival in patients with estrogen receptor (ER)-negative ( = 941), triple-negative (TNBC) phenotype ( = 538), or basal-like subtype ( = 293) breast cancers, but not in those patients with ER-positive breast cancer ( = 2,218). Together, these data demonstrate an Aurora-A/TPX2/HMMR molecular axis that intersects cell-cycle progression and cell migration. Tumor cell engraftment, migration, and cell-cycle progression share common regulation of the microtubule cytoskeleton through the Aurora-A/TPX2/HMMR axis, which has the potential to influence the survival of patients with ER-negative breast tumors. .

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A mouse model of amyotrophic lateral sclerosis-parkinsonism-dementia complex based on the consumption of cycad seed flour was used to determine whether the observed pathology of motor neuron loss begins in the distal axons or the spinal cord. Assessments of neuromuscular junction integrity and motor neurons were performed at multiple time points. Mice fed cycad pellets performed worse on the wire hang than controls. Microglial activation in cycad-fed mice was observed with motor neuron degeneration at 12 weeks, but reactive astrocyte proliferation was not observed. After 33 weeks of cycad feeding, motor neuron loss had stabilized, with no evidence of neuromuscular junction endplate denervation. These data suggest that neuronal pathology begins at the soma and proceeds distally in a 'dying forward' pattern.

Both rapamycin (RAPA) and cyclosporin A (CsA) are commonly used for immunosuppression, however their adverse side effects limit their application. Thus, it is of interest to develop novel means to enhance or preserve the immunosuppressive activity of RAPA or CsA while reducing their toxicity. Halofuginone (HF) has been recently tested as a potential immunosuppressant. This study investigated the interaction of HF with RAPA or with CsA in cell cultures. Cell proliferation in cultures was determined using methylthiazol tetrazolium assay, and cell apoptosis assessed by flow cytometric analysis and Western blot. The drug-drug interaction was determined according to Loewe’s equation or Bliss independence. Here, we showed that addition of HF to anti-CD 3 antibody-stimulated splenocyte cultures induced synergistic suppression of T cell proliferation in the presence of RAPA, indicated by an interaction index (γ) value of < 1.0 between HF and RAPA, but not in those with CsA. The synergistic interaction of RAPA with HF in the suppression of T cell proliferation was also seen in a mixed lymphocyte reaction and Jurkat T cell growth, and was positively correlated with an increase in cell apoptosis, but not with proline depletion. In cultured kidney tubular epithelial cells, HF attenuated the cytotoxicity of CsA. In conclusion, these data indicate that HF synergistically enhances anti-T cell proliferation of RAPA and reduces the nephrotoxicity of CsA in vitro, suggesting the potential use of HF for enhancing anti-T cell proliferation of RAPA and reducing CsA-mediated nephrotoxicity.