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1.  Evidence for participation of uterine natural killer cells in the mechanisms responsible for spontaneous preterm labor and delivery 
The purpose of this study was to determine in a mouse model whether uterine natural killer (uNK) cell cytotoxic activation induces infection/inflammation-associated preterm labor and delivery.
Study design
Wild type or interleukin (IL)-10−/− mice were injected intraperitoneally with lipopolysaccharide on gestational day 14. Mice were either killed for collection of uteroplacental tissue, spleen, and serum or allowed to deliver. Uteroplacental tissue was used for histology and characterization of uNK cells.
Low-dose lipopolysaccharide treatment triggered preterm labor and delivery in IL-10−/−, but not wild type mice, in a manner independent of progesterone levels. Preterm labor and delivery in IL-10−/− mice was associated with an increased number and placental infiltration of cytotoxic uNK cells and placental cell death. Depletion of NK cells or tumor necrosis factor (TNF)α neutralization in these mice restored term delivery. Furthermore, TNFα neutralization prevented uNK cell infiltration and placental cell apoptosis.
The uNK cell-TNFα-IL-10 axis plays an important role in the genesis of infection/inflammation-induced preterm labor/delivery.
PMCID: PMC3893044  PMID: 19114277
cytokines; inflammation; preterm birth; uterine natural killer cells
2.  TLR6 Modulates First Trimester Trophoblast Responses to Peptidoglycan1 
Intrauterine bacterial infections are a well-established cause of pregnancy complications. One key observation in a number of abnormal pregnancies is that placental apoptosis is significantly elevated. First trimester trophoblast cells are known to express TLR1 and TLR2 and to undergo apoptosis following exposure to Gram-positive bacterial peptidoglycan (PDG). Thus, the objectives of this study were to determine whether PDG-induced pregnancy complications are associated with placental apoptosis and to characterize the cellular mechanisms involved. We have demonstrated, using an animal model, that delivery of PDG to pregnant mice early in gestation resulted in highly elevated placental apoptosis, evidenced by trophoblast M-30 and active caspase 3 immunostaining. Using an in vitro model of human first trimester trophoblasts, apoptosis induced by PDG was found to be mediated by both TLR1 and TLR2 and that this could be blocked by the presence of TLR6. Furthermore, in the presence of TLR6, exposure to PDG resulted in trophoblast NF-κB activation and triggered these cells to secrete IL-8 and IL-6. The findings of this study suggest that a Gram-positive bacterial infection, through TLR2 and TLR1, may directly promote the elevated trophoblast cell death and that this may be the underlying mechanism of pregnancy complications, such as preterm delivery. Furthermore, the expression of TLR6 may be a key factor in determining whether the response to PDG would be apoptosis or inflammation.
PMCID: PMC3025812  PMID: 18424724
3.  Structure and expression of the maize (Zea mays L.) SUN-domain protein gene family: evidence for the existence of two divergent classes of SUN proteins in plants 
BMC Plant Biology  2010;10:269.
The nuclear envelope that separates the contents of the nucleus from the cytoplasm provides a surface for chromatin attachment and organization of the cortical nucleoplasm. Proteins associated with it have been well characterized in many eukaryotes but not in plants. SUN (Sad1p/Unc-84) domain proteins reside in the inner nuclear membrane and function with other proteins to form a physical link between the nucleoskeleton and the cytoskeleton. These bridges transfer forces across the nuclear envelope and are increasingly recognized to play roles in nuclear positioning, nuclear migration, cell cycle-dependent breakdown and reformation of the nuclear envelope, telomere-led nuclear reorganization during meiosis, and karyogamy.
We found and characterized a family of maize SUN-domain proteins, starting with a screen of maize genomic sequence data. We characterized five different maize ZmSUN genes (ZmSUN1-5), which fell into two classes (probably of ancient origin, as they are also found in other monocots, eudicots, and even mosses). The first (ZmSUN1, 2), here designated canonical C-terminal SUN-domain (CCSD), includes structural homologs of the animal and fungal SUN-domain protein genes. The second (ZmSUN3, 4, 5), here designated plant-prevalent mid-SUN 3 transmembrane (PM3), includes a novel but conserved structural variant SUN-domain protein gene class. Mircroarray-based expression analyses revealed an intriguing pollen-preferred expression for ZmSUN5 mRNA but low-level expression (50-200 parts per ten million) in multiple tissues for all the others. Cloning and characterization of a full-length cDNA for a PM3-type maize gene, ZmSUN4, is described. Peptide antibodies to ZmSUN3, 4 were used in western-blot and cell-staining assays to show that they are expressed and show concentrated staining at the nuclear periphery.
The maize genome encodes and expresses at least five different SUN-domain proteins, of which the PM3 subfamily may represent a novel class of proteins with possible new and intriguing roles within the plant nuclear envelope. Expression levels for ZmSUN1-4 are consistent with basic cellular functions, whereas ZmSUN5 expression levels indicate a role in pollen. Models for possible topological arrangements of the CCSD-type and PM3-type SUN-domain proteins are presented.
PMCID: PMC3017857  PMID: 21143845

Results 1-3 (3)