Downregulation of heat shock protein B8 decreases osteogenic differentiation potential of dental pulp stem cells during in vitro proliferation

OBJECTIVES

Tissue-derived stem cells, such as dental pulp stem cells (DPSCs), reduce differentiation capability during in vitro culture. We found that cultured DPSCs reduce expression of heat shock protein B8 (HspB8) and GIPC PDZ domain containing family member 2 (Gipc2). Our objectives were to evaluate the changes in DPSC composition during in vitro proliferation and to determine whether HspB8 and Gipc2 have function in differentiation potential of DPSCs.

MATERIALS AND METHODS

Different passages of rat DPSCs were evaluated for changes in CD90+ and/or CD271+ stem cells and changes in osteogenic potential. Real-time RT-PCR and immunostaining were conducted to determine expression of HspB8 and Gipc2. Expression of the genes in DPSCs was knocked down by siRNA, followed by osteogenic induction to evaluate the function of the genes.

RESULTS

About 90% of cells in the DPSC cultures were CD90+ and/or CD271+ cells without dramatic change during in vitro proliferation. The DPSCs at passages 3 to 5 (P3 to P5) possess strong osteogenic potential, but such potential was greatly reduced at later passages. Expression of HspB8 and Gipc2 was significantly reduced at P11 versus P3. Knock-down of HspB8 expression abolished osteogenic potential of the DPSCs, but knock-down of Gipc2 had no effect.

CONCLUSIONS

CD90+ and CD271+ cells are the major components of DPSCs in in vitro culture. High-level expression of HspB8 was critical for maintaining differentiation potential of DPSCs.

Analysis of bull (Bos taurus) seminal vesicle fluid proteome in relation to seminal plasma proteome

The existing knowledge on the bull seminal vesicle proteome, a major seminal plasma constituent, and its relationship with seminal plasma is limited. This knowledge is prerequisite for a better understanding of seminal plasma variability, which is linked to semen quality. The objective of this study was to characterize the proteomes of seminal vesicle fluid and seminal plasma and to compare them to better understand the origin of seminal plasma proteins. We collected ejaculates and seminal vesicle fluid postmortem from 6 mature Holstein Friesian bulls. We performed the analysis and identification of proteins using 2-dimensional electrophoresis coupled with matrix-assisted laser desorption/ionization mass spectrometry. We identified 105 proteins in bull seminal vesicle fluid and 88 proteins in seminal plasma. For both seminal vesicles and seminal plasma proteins described in our study, top biological functions were cellular movement, cell death and survival, and cellular growth and proliferation. Additionally, seminal vesicle fluid proteins were involved in protein degradation and synthesis. Seminal plasma proteins were also involved in cellular assembly and organization and cell-to-cell signaling and interactions. Proteins of both fluids were involved in the following canonical pathways: glycolysis, gluconeogenesis, liver X receptor/farnesoid X receptor, and farnesoid X receptor/retinoid X receptor activation. Additionally, seminal vesicle fluid proteins appeared to be involved in oxidative stress response mediated by nuclear factor E2-related factor 2. Our results described the bull seminal vesicle fluid proteome for the first time and allowed for significant expansion of the current knowledge on the bull seminal plasma proteome. Moreover, analysis indicated that both bull seminal vesicle fluid and seminal plasma proteomes contained interconnected protein groups related to protective functions, glycolysis, and the morphology and physiology of the spermatozoa. These proteins and their interactions could be targeted in future research.

Impact of cryopreservation on bull () semen proteome

Cryopreservation of bull spermatozoa is a well-established technique, allowing artificial insemination of cattle on a commercial scale. However, the extent of proteome changes in seminal plasma and spermatozoa during cryopreservation are not yet fully known. The objective of this study was to compare the proteomes of fresh, equilibrated, and cryopreserved bull semen (spermatozoa and seminal plasma) to establish the changes in semen proteins during the cryopreservation process. Semen was collected from 6 mature Holstein Friesian bulls. After sample processing, comparative analysis and identification of proteins was performed using 2-dimensional difference in-gel electrophoresis coupled with matrix-assisted laser desorption/ionization mass spectrometry. Analysis of spermatozoa extracts revealed that 25 identified protein spots, representing 16 proteins, underwent significant ( < 0.05) changes in abundance due to equilibration and cryopreservation. Eighteen protein spots decreased in abundance, 5 protein spots increased in abundance, and 2 protein spots showed different, specific patterns of abundance changes. Analysis of seminal fluid containing seminal plasma showed that 6 identified protein spots, representing 4 proteins, underwent significant ( < 0.05) changes in abundance due to equilibration and cryopreservation. Two protein spots increased in abundance and 4 decreased in abundance. Semen extending and equilibration seems to be responsible for a significant portion of the proteome changes related to cryopreservation technology. Most sperm proteins affected by equilibration and cryopreservation are membrane bound, and loss of those proteins may reduce natural spermatozoa coating. Further research is needed to unravel the mechanisms of the particular protein changes described in this study and establish the relationship between those changes and sperm quality.

Anti-sperm antibodies and seminal characteristics after testicular biopsy or epididymal aspiration in dogs

A study was performed to determine if performing testicular biopsies or epididymal aspirates in dogs would induce sperm-bound anti-sperm antibodies (ASA), affect long-term sperm production or semen quality. Semen was collected from 8 mature dogs 3 times a week before and after hemicastration and then 3 times a week after testicular biopsy (n=3 and 1 control) or epididymal aspiration (n=3 and 1 control). Detection of anti-sperm IgG (ASA) on sperm cells was performed by flow cytometry analysis using a flow cytometer. Two dogs with testicular biopsies became positive for ASA 16 d after testicular biopsy and remained positive for 7 and 9 d, respectively. One dog that had an epididymal aspirate became positive 13 d after epididymal aspiration and remained positive for 35 d. One dog became positive 21 d after hemicastration and remained positive for 28 d. Sperm output declined significantly in 7 of 8 dogs after hemicastration. A control epididymal aspirate treatment dog had decreased sperm output, and a testicular biopsy treatment dog had increased sperm output. None of the dogs with ASA had significant changes in sperm output after treatment. Sperm motility declined significantly in 3 dogs after hemicastration. An epididymal aspiration treatment dog had a decrease in sperm motility, a control epididymal aspirate treatment dog and a control testicular biopsy treatment dog each had increases in sperm motility. None of the dogs with ASA had significant changes in motility. The percentage of normal spermatozoa significantly decreased in 3 dogs and significantly increased in 1 dog after hemicastration. Two dogs that had testicular biopsies and 1 dog that had an epididymal aspiration had decreases in percent normal sperm. Two of 3 dogs with decreases in percent normal sperm after treatment had ASA, but 2 dogs with ASA had no change in motility. Hemicastration, epididymal aspiration, and testicular biopsy can induce ASA production within 2 wk of the procedure, but ASA are transient and do not have a predictably negative effect on total sperm output or motility. Testicular biopsy and epididymal aspiration are safe diagnostic procedures, but further work investigating post-treatment fertility must be done before final conclusions can be made.

Effect of thalidomide on apoptosis of lymphocytes and neutrophils

Thalidomide causes congenital anomalies and it is immunomodulatory. These properties could be explained by an ability to alter the orderly process of programmed cell death during embryogenesis and modulation of apoptosis of lymphoid and/or myeloid cells in the immune response. Apoptosis of lymphoid and myeloid cells was studied by measuring the percentage of cells capable of excluding propidium iodide and expressing phosphatidylserine on their outer membrane. In addition, expression of Fc gamma RIII (CD16) was used to assess neutrophil apoptosis. Thalidomide did not affect the rate of apoptosis of CTLL-2 cells deprived of, or supplemented with, IL-2; of T-cells (mitogen-stimulated or resting) or of neutrophils. However, neutrophils obtained from HIV-infected patients treated with thalidomide showed reduced expression of CD16, a surrogate marker for apoptosis of neutrophils. Thalidomide's effect on neutrophil apoptosis in vivo warrants further investigation.

Memory and CD8+ are the predominant bovine bronchoalveolar lymphocyte phenotypes

Bovine lymphocytes obtained by bronchoalveolar lavage (BAL) of healthy calves were simultaneously analyzed and compared to peripheral blood lymphocytes using monoclonal antibodies specific for bovine leukocyte differentiation antigens. Phenotypic differences were observed between bronchoalveolar and peripheral blood T-lymphocyte subpopulations, demonstrating selective lymphocyte migration to the bovine lung. The bronchoalveolar and peripheral blood T-lymphocyte populations, defined by expression of CD2, were similar, but bronchoalveolar T lymphocytes were predominately CD8+ while peripheral blood T cells were predominately CD4+. In addition, memory lymphocytes, characterized by low expression of CD45R and activated lymphocytes (CD25+), were found in significantly higher proportions in the bronchoalveolar compartment. The proportion of gammadelta T lymphocytes was, however, significantly higher in peripheral blood. B cells were observed in similar proportions in the bronchoalveolar compartment and peripheral blood.

Isolation and characterization of the canine melanoma antigen recognized by the murine monoclonal antibody IBF9 and its distribution in cultured canine melanoma cell lines

OBJECTIVE

To characterize the canine melanoma antigen recognized by the murine monoclonal antibody IBF9 as to its cellular location, molecular size, protein and glycogen contents, and distribution in cell lines.

SAMPLE POPULATION

7 cultured canine melanoma cell lines.

PROCEDURE

Molecular characteristics of the antigen were determined by western blotting, enzymatic digestion studies, and tunicamycin inhibition studies. Distribution of the antigen in the cultured melanoma cell lines was determined by flow cytometry.

RESULTS

The antigen consists of 2 proteins with molecular mass of 89 and 85 kd. Tunicamycin and enzymatic digestion studies indicated that these proteins contained little glycosylation. Immunogold and immunofluorescence studies localized the antigen to the cell surface. Antigen expression was consistent within each cell line, with > 90% of the cells positive for all cell lines except 1 (80%). Percentage of positive cells and relative intensity of immunostaining were constant throughout all phases of the cell cycle.

CONCLUSIONS

The antigen identified by MAB IBF9 is a well-conserved and highly expressed cell surface protein present during all phases of the cell cycle in all malignant canine melanoma cell lines examined.

CLINICAL RELEVANCE

Because of consistency in expression, the antigen may have potential for use in dogs for melanoma immunodiagnostics and immunotherapy.

Evidence for genetic control of vaccine-induced antibody responses in cattle

The purpose of our study was to identify evidence for genetic control of immune responses in cattle. To address this question, we evaluated the variation of antibody responses induced by vaccination with Brucella abortus Strain 19, a live attenuated bacterial vaccine, in large half-sibling families. The data were analyzed using a parametric statistical model that incorporated the effects of sire, bovine major histocompatibility complex (BoLA) types and parameters related to the experimental design. The BoLA types represented a readily identifiable marker, analogous to those known to be associated with genetic control of immune responses in other mammals. Variation between individual animals within our test population was significant but we were able to identify both individual animals and families with high or low antibody production phenotypes. In several cases, these traits were significantly correlated with individual bulls, suggesting the existence of sire effects, or with individual BoLA types. These findings are consistent with the theory that at least two separate genes or genetic systems contribute to the control of bovine antibody responses to B. abortus vaccination. These genetic effects are likely to be analogous to those identified in several species of laboratory rodents and humans.

Cryopreservation of bovine buffy coat leukocytes for use in immunologic studies

A simple cryogenic technique for preserving bovine buffy coat leukocytes was developed. This was coupled with a variation of the standard discontinuous gradient technique to purify mononuclear cells that retained immunologic function. The total number of mononuclear cells recovered from cyropreserved samples were only 87 to 42% of those recovered from freshly obtained blood samples. However, the functional capabilities of mononuclear cells from cyopreserved buffy coat preparations were retained. Polyclonal proliferative responses to 3 mitogens were measured, using a titration of mitogen concentrations, and were found to be normal, compared with those of cells isolated from fresh blood. Blood samples collected after vaccination with Brucella abortus contained leukocytes that responded to irradiated B abortus. These antigen-specific responses were also retained through cyopreservation. Cell surface expression of T-lymphocyte antigens, CD2, CD4, and CD8, and cell-surface IgM on B lymphocytes was also evaluated. Flow cytometric analysis of fresh and cryopreserved mononuclear cell preparations indicated that the relative proportions of different subpopulations were not altered. The technical simplicity of our cryopreservation system will allow processing of large numbers of samples with the ability to assay various immune functions at a later time.

Cell fusion caused by herpes simplex virus-1 (HSV-1) strains tsB5 and MP is inhibited at pH 6.7 and pH 7.0

We investigated the effect of different pH conditions on Vero cell cultures infected with herpes simplex virus-1 (HSV-1) wild-type strain KOS, and syncytial mutants HSV-1 HFEM (tsB5) and HSV-1 mp (MP). Cell fusion was inhibited when infected cells were continuously incubated with culture media adjusted to pH 6.7 or pH 7.0. Inhibition of cell fusion was rapidly reversible when infected cell cultures were returned to pH 7.5. The rate of synthesis and cell-surface expression of virus-specified glycoproteins gB, gC, gD, and gH were not affected during continuous incubation at pH 7.0, but they were reduced at pH 6.7 in comparison to pH 7.5. At later hours p.i. however, these glycoproteins continued to accumulate at all tested pH levels. Accumulation of infectious virions was substantially reduced for MP, KOS, and tsB5 at pH 6.7. At pH 7.0, KOS and tsB5 titers were greatly reduced but MP titers were not affected.

Analysis of the genes encoding the largest subunit of RNA polymerase II in Arabidopsis and soybean

We have cloned and sequenced the gene encoding the largest subunit of RNA polymerase II (RPB1) from Arabidopsis thaliana and partially sequenced genes from soybean (Glycine max). We have also determined the nucleotide sequence for a number of cDNA clones which encode the carboxyl terminal domains (CTDs) of RNA polymerase II from both soybean and Arabidopsis. The Arabidopsis RPB1 gene encodes a polypeptide of approximately 205 kDa, consists of 12 exons, and encompasses more than 8 kb. Predicted amino acid sequence shows eight regions of similarity with the largest subunit of other prokaryotic and eukaryotic RNA polymerases, as well as a highly conserved CTD unique to RNA polymerase II. The CTDs in plants, like those in most other eukaryotes, consist of tandem heptapeptide repeats with the consensus amino acid sequence PTSPSYS. The portion of RPB1 which encodes the CTD in plants differs from that of RPB1 of animals and lower eukaryotes. All the plant genes examined contain 2-3 introns within the CTD encoding regions, and at least two plant genes contain an alternatively spliced intron in the 3' untranslated region. Several clustered amino acid substitutions in the CTD are conserved in the two plant species examined, but are not found in other eukaryotes. RPB1 is encoded by a multigene family in soybean, but a single gene encodes this subunit in Arabidopsis and most other eukaryotes.