Single-cell analysis of human skin identifies CD14+ type 3 dendritic cells co-producing IL1B and IL23A in psoriasis.

Inflammatory skin diseases including atopic dermatitis (AD) and psoriasis (PSO) are underpinned by dendritic cell (DC)-mediated T cell responses. Currently, the heterogeneous human cutaneous DC population is incompletely characterized, and its contribution to these diseases remains unclear. Here, we performed index-sorted single-cell flow cytometry and RNA sequencing of lesional and nonlesional AD and PSO skin to identify macrophages and all DC subsets, including the newly described mature LAMP3+BIRC3+ DCs enriched in immunoregulatory molecules (mregDC) and CD14+ DC3. By integrating our indexed data with published skin datasets, we generated a myeloid cell universe of DC and macrophage subsets in healthy and diseased skin. Importantly, we found that CD14+ DC3s increased in PSO lesional skin and co-produced IL1B and IL23A, which are pathological in PSO. Our study comprehensively describes the molecular characteristics of macrophages and DC subsets in AD and PSO at single-cell resolution, and identifies CD14+ DC3s as potential promoters of inflammation in PSO.

Glioma-propagating cells as an in vitro screening platform: PLK1 as a case study.

Gliomas are the most devastating of primary adult malignant brain tumors. These tumors are highly infiltrative and can arise from cells with extensive self-renewal capability and chemoresistance, frequently termed glioma-propagating cells (GPCs). GPCs are thus the plausible culprits of tumor recurrence. Treatment strategies that eradicate GPCs will greatly improve disease outcome. Such findings support the use of GPCs as in vitro cellular systems for small-molecule screening. However, the nuances in using GPCs as a cellular screening platform are not trivial. These slow-growing cells are typically cultured as suspension, spheroid structures in serum-free condition supplemented with growth factors. Consequently, replenishment of growth factors throughout the screening period must occur to maintain cells in their undifferentiated state, as the more lineage-committed, differentiated cells are less tumorigenic. We present a case study of a small-molecule screen conducted with GPCs and explain how unique sphere activity assays were implemented to distinguish drug efficacies against the long-term, self-renewing fraction, as opposed to transient-amplifying progenitors, the latter of which are detected in conventional viability assays. We identified Polo-like kinase 1 as a regulator of GPC survival. Finally, we leveraged on public glioma databases to illustrate GPC contribution to disease progression and patient survival outcome.

Parkin pathway activation mitigates glioma cell proliferation and predicts patient survival.

Mutations in the parkin gene, which encodes a ubiquitin ligase, are a major genetic cause of parkinsonism. Interestingly, parkin also plays a role in cancer as a putative tumor suppressor, and the gene is frequently targeted by deletion and inactivation in human malignant tumors. Here, we investigated a potential tumor suppressor role for parkin in gliomas. We found that parkin expression was dramatically reduced in glioma cells. Restoration of parkin expression promoted G(1) phase cell-cycle arrest and mitigated the proliferation rate of glioma cells in vitro and in vivo. Notably, parkin-expressing glioma cells showed a reduction in levels of cyclin D1, but not cyclin E, and a selective downregulation of Akt serine-473 phosphorylation and VEGF receptor levels. In accordance, cells derived from a parkin-null mouse model exhibited increased levels of cyclin D1, VEGF receptor, and Akt phosphorylation, and divided significantly faster when compared with wild-type cells, with suppression of these changes following parkin reintroduction. Clinically, analysis of parkin pathway activation was predictive for the survival outcome of patients with glioma. Taken together, our study provides mechanistic insight into the tumor suppressor function of parkin in brain tumors and suggests that measurement of parkin pathway activation may be used clinically as a prognostic tool in patients with brain tumor.

Cryopreservation of cancer-initiating cells derived from glioblastoma.

Glioblastoma multiforme (GBM) represents the most devastating adult brain tumor. GBM follows a hierarchical development in oncogenesis, with a sub-population of cells - brain tumor stem cells (BTSCs), exhibiting tumor-initiating potential. BTSCs possess extensive self-renewal capability and can repopulate the entire tumor mass. They are resistant to conventional therapies, suggesting that they are the likely candidates of tumor recurrence. Their eradication is thus important for an effective cure. Previous works showed that human-derived BTSCs could be stably maintained for 10-15 passages in serum-free condition, and gene expression and karyotypic hallmarks similar to the primary tumors were preserved. However, primary cells have been shown to sustain additional karyotypic aberrations owing to the harsh conditions of extended in vitro serial passage. Several investigators have proposed passaging these cells in xenograft models. A limitation of such an approach is the inability to return to identical passages for experimental repetitions, or the unavailability of suitably-aged mice for implantation. We have devised a method to cryopreserve BTSCs and that important characteristics were maintained, establishing a repository for drug screening endeavors.

Aurora B kinase activity is required to prevent polar cortical ingression during cytokinesis.

Cytokinesis requires proper regulation of microtubule dynamics. It has been suggested that dynamic astral microtubules prevent cortical ingression. However, it remains unknown how astral microtubules maintain their dynamic state. Here we show that aurora B kinase, a component of the chromosome passenger complex, is required to sustain the dynamic state of astral microtubules during cytokinesis. Treatment of HeLa cells with Hesperadin, an inhibitor of aurora B kinase, caused abnormal cortical protrusion, leading to cortical ingression in the protruding region and cytokinesis failure. Actin filaments, myosin II, and RhoA failed to localize at the equator but instead distributed along the lateral and/or polar cortex in cells treated with Hesperadin. Time-lapse analyses of microtubule dynamics showed that, in cells treated with Hesperadin, abnormally bundled astral microtubules targeted the protruding region. Mitotic kinesin-like protein 1 (MKLP1), a component of the spindle midzone required for bundling of microtubules, was not detected along bundled astral microtubules in cells treated with Hesperadin, suggesting that factors other than MKLP1 may be involved in this process. Our results suggest that aurora B kinase activity is required for proper regulation of microtubule dynamics to ensure that cytokinesis occurs precisely at the cell equator.

Specific distribution of overexpressed aurora B kinase during interphase of normal epithelial cells.

BACKGROUND: It is known that aurora B, a chromosomal passenger protein responsible for the proper progression of mitosis and cytokinesis, is overexpressed throughout the cell cycle in cancer cells. Overexpression of aurora B produced multinuclearity and induced aggressive metastasis, suggesting that overexpressed aurora B has multiple functions in cancer development. However, the detailed dynamics and functions of overexpressed aurora B are poorly understood. RESULTS: We overexpressed GFP fused aurora B kinase in normal rat kidney epithelial cells. Using spinning disk confocal microscopy, we found that overexpressed aurora B-GFP was predominantly localized in the nucleus and along the cortex as a dot-like or short filamentous structure during interphase. Time-lapse imaging revealed that a cytoplasmic fraction of overexpressed aurora B-GFP was incorporated into the nucleus after cell division. Immunofluorescence showed that the nuclear fraction of overexpressed aurora B did not induce ectopic phosphorylation of histone H3 after cell division. The cytoplasmic fraction of overexpressed aurora B-GFP was mainly associated with cortical actin filaments but not stress fibers. Myosin II regulatory light chain, one of the possible targets for aurora B, did not colocalize with cortical aurora B-GFP, suggesting that overexpressed aurora B did not promote phosphorylation of myosin II regulatory light chain in interphase cells. CONCLUSION: We conclude that overexpressed aurora B has a specific localization pattern in interphase cells. Based on our findings, we propose that overexpressed aurora B targets the nuclear and cortical proteins during interphase, which may contribute to cancer development and tumor metastasis.