[Effects of small GTP-binding protein GDP dissociation stimulator on adipocyte hypertrophy and glucose metabolism disorder in mice].

Objective: To explore the effect and mechanism of small GTP-binding protein GDP dissociation stimulator (SmgGDS) on the development of obesity. Methods: (1) 8-week-old C57BL/6J mice were randomly assigned to normal diet and high fat diet group, with 6 mice in each group. They were fed regular feed and a high fat diet containing 60% fat for 4 months, respectively. The expression of SmgGDS in epididymal adipose tissue (eWAT), liver, and skeletal muscle were measured using Western-blot. (2) 6-week-old wild-type (WT) and SmgGDS knockdown (KD) mice were divided into four groups, each receiving high fat diet for 4 months (7 in each group) and 7 months (9 in each group). Glucose tolerance test (GTT) and insulin tolerance test (ITT) were conducted; The weight, adipose tissue, and liver weight of mice were recorded; HE staining examined adipose tissue structural changes; Western-blot determined extracellular signal-regulated kinase (ERK) 1/2 phosphorylation levels in eWAT; Real time fluorescence quantitative polymerase chain reaction (RT-qPCR) was used to detect mRNA levels of CCAAT/enhancer binding protein α (C/EBPα), C/EBPß and peroxisome proliferator activated receptor γ (PPARγ) in eWAT. (3) Mouse embryonic fibroblasts (MEFs) extracted from WT and KD mice were induced for differentiation. Oil red O staining and Western-blot were used to detect lipid droplet and expression of SmgGDS and phospho-ERK; C/EBPα, C/EBPß and PPARγ mRNA levels were measured using RT-qPCR. (4) 10-week-old C57BL/6J mice were randomly assigned into two groups, with 7 mice in each group. Mice were infected with SmgGDS overexpressing adeno-associated virus (AAV-SmgGDS) or empty vector intraperitoneally, then fed with high fat diet. After 4 weeks, performed GTT and ITT; Recorded the weight and adipose tissue weight of mice; HE staining was used to analyze structural changes of eWAT; Western-blot was used to detect the phosphorylation level of ERK in eWAT. Results: (1) The expression of SmgGDS was significantly upregulated in eWAT of high fat diet fed mice (normal diet group: 0.218±0.037, high fat diet group:0.439±0.072, t=2.74, P=0.034). (2) At 4 months of high fat diet intervention, the glucose tolerance (60 minutes after glucose injection, WT group: 528 mg/dl±21 mg/dl, KD group: 435 mg/dl±17 mg/dl, t=3.47, P=0.030; 90 minutes, WT group: 463 mg/dl±24 mg/dl, KD group: 366 mg/dl±18 mg/dl, t=3.23, P=0.047;120 minutes, WT group: 416 mg/dl±21 mg/dl, KD group: 297 mg/dl±16 mg/dl, t=4.49, P=0.005) and insulin sensitivity (15 minutes after insulin injection, WT group: 77.79%±3.45%, KD group: 54.30%±2.92%, t=3.49, P=0.005; 30 minutes, WT group: 62.27%±5.31%, KD group: 42.25%±1.85%, t=2.978, P=0.024; 90 minutes, WT group: 85.69%±6.63%, KD group: 64.71%±5.41%, t=3.120, P=0.016) of KD mice were significantly improved compared to the WT group, with an increase in eWAT weight ratio (WT: 4.19%±0.18%, KD: 5.12%±0.37%, t=2.28, P=0.042), but a decrease in average adipocyte area (WT group: 5221 µm²±241 µm², KD group: 4410 µm²±196 µm², t=2.61, P=0.026). After 7 months of high fat diet, the eWAT weight ratio of KD mice decreased (WT: 5.02%±0.20%, KD: 3.88%±0.21%, t=3.92, P=0.001) and adipocyte size decreased (WT group: 6 783 µm²±390 µm², KD group: 4785 µm²±303 µm², t=4.05, P=0.002). The phospho-ERK1 in eWAT increased (WT group: 0.174±0.056, KD group: 0.588±0.147, t=2.64, P=0.025), and mRNA level of PPARγ significantly decreased (WT group: 1.018±0.128, KD group: 0.029±0.015, t=7.70, P=0.015). (3) The expression of SmgGDS was significantly increased in differentiated MEF (undifferentiated: 6.789±0.511, differentiated: 10.170±0.523, t=4.63, P=0.010); SmgGDS knock-down inhibited lipid droplet formation in MEF (WT group: 1.00±0.02, KD group: 0.88±0.02, t=5.05, P=0.007) and increased ERK1 (WT group: 0.600±0.179, KD group: 1.325±0.102, t=3.52, P=0.025) and ERK2 (WT group: 2.179±0.687, KD group: 5.200±0.814, t=2.84, P=0.047) activity, which can be reversed by ERK1/2 inhibitor. (4) SmgGDS over expression resulted in weight gain, increased eWAT weight (control group: 3.29%±0.36%, AAV-SmgGDS group: 4.27%±0.26%, t=2.20, P=0.048) and adipocyte size (control group: 3525 µm²±454 µm², AAV-SmgGDS group: 5326 µm²±655 µm², t=2.26, P=0.047), impaired insulin sensitivity(30 minutes after insulin injection, control group: 44.03%±4.29%, AAV-SmgGDS group: 62.70%±2.81%, t=3.06, P=0.019), and decreased ERK1 (control group: 0.829±0.077, AAV-SmgGDS group: 0.326±0.036, t=5.96, P=0.001)and ERK2 (control group: 5.748±0.287, AAV-SmgGDS group: 2.999±0.845, t=3.08, P=0.022) activity in eWAT. Conclusion: SmgGDS knockdown improves obesity related glucose metabolism disorder by inhibiting adipogenesis and adipose tissue hypertrophy, which is associated with ERK activation.

Inhibition of invasion and migration of prostate cancer cells by miRNA-509-5p via targeting MDM2.

Prostate cancer is a common malignancy of the male reproductive-urinary system. MDM2 is an oncogene, whose expression can be regulated by microRNA (miRNA). The present study investigated the expression and correlation of miRNA-509-5p and MDM2 to determine the mechanism of their function in invasion and migration of prostate cancer cells. RT-PCR was performed to detect the expression of miRNA-509-5p and MDM2 in tumor, tumor-adjacent, and normal tissues, obtained from prostate cancer patients, using the HGC-27 cell line as an in vitro model. Cultured HGC-27 cells were transfected with miRNA-509-5p mimics, miRNA-509-5p inhibitor, and mimic control. Expression levels of miRNA-509-5p and MDM2 were quantified by RT-PCR. Cell proliferation and invasion/migration were examined by the MTT and transwell assays, respectively. MiRNA-509-5p was significantly down-regulated in prostate cancer cells exhibiting high MDM2 mRNA levels. MiRNA mimic transfection elevated miRNA levels and suppressed MDM2 expression. With prolonged incubation time, the proliferation ratio and OD values of miRNA-509-5p mimic transfected cells decreased, along with decrease in cell migration and invasion. These results suggested that miRNA-509-5p negatively regulates MDM2 expression via targeting the 3'-UTR of genes. As a novel tumor suppressor, miRNA-509-5p in prostate cancer HGC-27 cells can suppress MDM2 expression and inhibit cell proliferation, invasion, and migration. Therefore, miRNA-509-5p could be used as a novel therapeutic agent in the treatment of prostate cancer.

Region-specific growth properties and trophic requirements of brain- and spinal cord-derived rat embryonic neural precursor cells.

To determine whether neural precursor cells have region-specific growth properties, we compared the proliferation, mitogenicity, and differentiation of these cells isolated from the embryonic day 16 rat forebrain and spinal cord. Neural precursor cells isolated from both regions were cultured in growth medium supplemented with epidermal growth factor, basic fibroblast growth factor, or epidermal growth factor+basic fibroblast growth factor. Under all three conditions, both neural precursor cell populations proliferated for multiple passages. While spinal cord-derived neural precursor cells proliferated moderately faster in epidermal growth factor-enriched growth medium, brain-derived cells proliferated much faster in basic fibroblast growth factor-enriched growth medium. When exposed to both epidermal growth factor and basic fibroblast growth factor, the two neural precursor cell populations expanded and proliferated more rapidly than when exposed to a single factor, with brain-derived neural precursor cells expanding significantly faster than spinal cord-derived ones (P<0.0001). Differentiation studies showed that both neural precursor cell populations were multi-potent giving rise to neurons, astrocytes, and oligodendrocytes. However, neuronal differentiation from brain-derived neural precursor cells was greater than spinal cord-derived ones (11.95+/-5.00% vs 1.92+/-1.13%; passage 2). Further, the two neural precursor cell populations differentiated into a similar percentage of oligodendrocytes (brain: 8.66+/-5.85%; spinal cord: 7.69+/-3.91%; passage 2). Immunofluorescence and Western blot studies showed that neural precursor cells derived from both regions expressed receptors for basic fibroblast growth factor and epidermal growth factor. However, brain-derived neural precursor cells expressed higher levels of the two receptors than spinal cord-derived ones in growth medium containing epidermal growth factor+basic fibroblast growth factor. Thus, our results showed that neural precursor cells isolated from the two regions of the CNS have distinct properties and growth requirements. Identifying phenotypic differences between these neural precursor cell populations and their growth requirements should provide new insights into the development of cell therapies for region-specific neurological degenerative diseases.

CD44 expression in papillary serous endometrial carcinoma.

The objective of this paper is to evaluate the relationship between CD44 expression and the clinicopathologic features of papillary serous endometrial cancer. CD44 expression was assessed in 32 cases of papillary serous endometrial carcinoma by standard immunohistochemical staining techniques. Clinicopathologic features including myometrial invasion, nodal metastases, tumor spread, stage, and the shedding of malignant cells on cervical cytology were reviewed. The Chi-square test was used for statistical analysis. CD44 was not expressed in 81% of patients with papillary serous endometrial carcinoma. Malignant cells were seen on cervical cytology in 68% of all cases with significantly more in the CD44-negative group (78% vs. 33%, P 0.05). CD44 expression was not related to stage, myometrial invasion, nodal involvement, or intraperitoneal spread. We conclude that the cell adhesion molecule CD44 is expressed infrequently in papillary serous endometrial carcinoma. Shedding of malignant cells on cervical cytology is common in papillary serous endometrial cancer and occurs more frequently in CD44-negative cases. CD44 expression doesn't appear to be related to known prognostic features such as nodal metastases or stage. The biologic aggressiveness of this tumor type may, in part, be related to its lack of CD44 expression.

The acid-fast stain is a superior stain for use in the mean mature spermatid count for testicular biopsies.

The mean mature spermatid count (MMSC) provides a useful, simplified quantitative evaluation of human spermatogenesis that is based on the number of mature spermatids in histological sections of testicular biopsies. Here, the activity of the acid-fast (AF) stain was compared to that of the usual hematoxylin and eosin (H&E) stain in performing the MMSC. Thirty bilateral testicular biopsies showing normal spermatogenesis were chosen retrospectively from 15 subfertile patients with obstructive azoospermia or severe oligospermia. The MMSC was determined on each biopsy by utilizing both H&E and AF stains. The AF stain proved to be specific for the mature spermatids normally counted for the MMSC. It simplified recognition of mature spermatids, thereby shortening the overall time required for the procedure. The mean AF MMSC was lower than the mean H&E MMSC, and the mean interobserver differences were decreased. The AF stain is a superior stain for the MMSC when used in conjunction with the H&E stain for descriptive histology.

Association of human Pur alpha with the retinoblastoma protein, Rb, regulates binding to the single-stranded DNA Pur alpha recognition element.

The retinoblastoma protein, Rb, is detected in extracts of monkey CV-1 cells complexed with Pur alpha, a sequence-specific single-stranded DNA-binding protein implicated in control of gene transcription and DNA replication. These complexes can be immunoextracted from cell lysates using monoclonal antibodies to either Pur alpha or Rb. The Pur alpha-Rb complexes contain a form of Pur alpha with extensive post-synthetic modification, as demonstrated following expression of Pur alpha cDNA fused to a 9-amino acid epitope tag. Human Pur alpha, expressed as a glutathione S-transferase fusion protein, specifically binds to the hypophosphorylated form of Rb with an affinity as high as that of SV40 large T-antigen. In the absence of DNA, glutathione S-transferase-Pur alpha binds to p56RB, an NH2-terminal-truncated Rb protein purified from Escherichia coli, containing the T-antigen binding domain, to form multimeric complexes. The single-stranded DNA Pur alpha recognition element disrupts these complexes. Conversely, high concentrations of p56RB prevent Pur alpha binding to DNA. Through use of a series of deletion mutants, the DNA binding activity of Pur alpha is localized to a series of modular amino acid repeats. Rb binding involves a Pur alpha region with limited homology to the Rb-binding region of SV40 large T-antigen. Binding of Pur alpha to p56RB, the COOH-terminal portion of Rb, is inhibited by a synthetic peptide containing the T-antigen Rb-binding motif.

Localization of PURA, the gene encoding the sequence-specific single-stranded-DNA-binding protein Pur alpha, to chromosome band 5q31.

Pur alpha (PurA) is a sequence-specific single-stranded-DNA-binding protein implicated in control of both DNA replication and transcription. We have localized the Pur alpha gene (PURA) to human chromosome band 5q31 by fluorescence in situ hybridization with a 16-kb genomic probe together with hybridization of a cDNA probe to blots of DNA from human-hamster cell lines containing individual human chromosomes. Sequences with homology to the PURA locus are also present at 6q14. The 5q31 locus is frequently deleted in myelogenous leukemia and other cancers.

Conservation in human and mouse Pur alpha of a motif common to several proteins involved in initiation of DNA replication.

Pur alpha is a sequence-specific single-stranded DNA-binding protein with affinity for an element present in several eukaryotic origins of DNA replication (ori) and gene regulatory regions. We report here the cDNA sequence for mouse pur alpha and an extraordinary degree of conservation between human and mouse Pur alpha (hPurA and mPurA, respectively). There are only two single-amino-acid (aa) changes between hPurA (322 aa) and mPurA (321 aa). One PurA region of 22 aa, termed the 'psycho' motif, possesses significant homology to a counterpart in the SV40 large T-antigen, to several other transforming proteins of DNA tumor viruses, and to certain cellular proteins in yeast and human cells that may also be involved in the initiation of DNA replication.

Sequence of cDNA comprising the human pur gene and sequence-specific single-stranded-DNA-binding properties of the encoded protein.

The human Pur factor binds strongly to a sequence element repeated within zones of initiation of DNA replication in several eukaryotic cells. The protein binds preferentially to the purine-rich single strand of this element, PUR. We report here the cloning and sequencing of a cDNA encoding a protein with strong affinity for the PUR element. Analysis with a series of mutated oligonucleotides defines a minimal single-stranded DNA Pur-binding element. The expressed Pur open reading frame encodes a protein of 322 amino acids. This protein, Pur alpha, contains three repeats of a consensus motif of 23 amino acids and two repeats of a second consensus motif of 26 amino acids. Near its carboxy terminus, the protein possesses an amphipathic alpha-helix and a glutamine-rich domain. The repeat region of Pur cDNA is homologous to multiple mRNA species in each of several human cell lines and tissues. The HeLa cDNA library also includes a clone encoding a related gene, Pur beta, containing a version of the 23-amino-acid consensus motif similar, but not identical, to those in Pur alpha. Results indicate a novel type of modular protein with capacity to bind repeated elements in single-stranded DNA.