A role for pericytes as microenvironmental regulators of human skin tissue regeneration.

The cellular and molecular microenvironment of epithelial stem and progenitor cells is poorly characterized despite well-documented roles in homeostatic tissue renewal, wound healing, and cancer progression. Here, we demonstrate that, in organotypic cocultures, dermal pericytes substantially enhanced the intrinsically low tissue-regenerative capacity of human epidermal cells that have committed to differentiate and that this enhancement was independent of angiogenesis. We used microarray analysis to identify genes expressed by human dermal pericytes that could potentially promote epidermal regeneration.

MAD1 and c-MYC regulate UBF and rDNA transcription during granulocyte differentiation.

The regulation of cell mass (cell growth) is often tightly coupled to the cell division cycle (cell proliferation). Ribosome biogenesis and the control of rDNA transcription through RNA polymerase I are known to be critical determinants of cell growth. Here we show that granulocytic cells deficient in the c-MYC antagonist MAD1 display increased cell volume, rDNA transcription and protein synthesis.

Analysis of human megakaryocytic cells using dual-color immunofluorescence labeling.

Background: Megakaryocytes are classically identified by their cellular morphology and expression of platelet glycoproteins.

Methods: In this study, the expression of GPIIIa (CD61) on hemopoietic cells was analyzed by dual-fluorescence flow cytometry.

Results: All monocytic cells (CD14+) were shown to coexpress CD61.

Ultrastructure of primitive hematopoietic stem cells isolated using probes of functional status.

The most primitive hematopoietic stem cells capable of longterm reconstitution of the entire hematopoietic system following transplantation are characterized by their ability to exclude both Rhodamine 123 and Hoechst 33342 dyes (Rh/Ho(dull)), and are an appropriate target population for the determination of stem cell ultrastructure. We have used a fluorescence-activated cell sorter to enrich to near purity these rare, highly quiescent cells. Analysis of the in vitro growth characteristics of Rh/Ho(dull) cells demonstrated an obligatory requirement for multiple growth factors, with 62% of the sorted population having the capacity to form colonies in the presence of CSF-1 + IL-1alpha + IL-3 + SCF.

A NIMA homologue promotes chromatin condensation in fission yeast.

Entry into mitosis requires p34(cdc2), which activates downstream mitotic events through phosphorylation of key target proteins. In Aspergillus nidulans, the NIMA protein kinase has been identified as a potential downstream target and plays a role in regulating chromatin condensation at mitosis. nimA- mutants arrest in a state that physically resembles interphase even though p34(cdc2) is fully active.

Enhancement of radiation-induced regrowth delay by gemcitabine in a human tumor xenograft model.

Gemcitabine, a cytidine nucleoside analogue, has schedule-dependent antitumor activity in vitro and in vivo. Gemcitabine also has dose- and time-dependent radiosensitization properties in vitro. Thus it may have therapeutic application in combination with radiation.

Expression of the tumor-associated mucin MUC1 in an ovarian tumor cell line.

Epithelial sialomucins constitute a family of high-molecular-weight glycoproteins associated with epithelial cell surfaces. Aberrant expression of these molecules has been observed in certain types of human epithelial tumors. Members of the MUC1 family of mucins isolated from different tissue types have been shown to differ in biochemical properties and in immunological reactivity.