dissection-coronal-slice-preparation-developing-mouse-pituitary

Dissection and Coronal Slice Preparation of Developing Mouse Pituitary Gland

The pituitary gland or hypophysis is an important endocrine organ secreting hormones essential for homeostasis. It consists of two glands with separate ...

Second Military Medical University

To investigate the expression of RhoA mRNA in colorectal neoplasms.

[RhoA gene expression in colorectal carcinoma].

Previous studies have shown that dexamethasone (Dex) induces the expression of TGF-beta1 in androgen-independent prostate cancer both in vitro and in vivo. However, it is not clear whether Dex has a direct effect on the expression of TGF-beta receptors. In this study, using the androgen-independent human prostate cancer cell line, PC-3 cells, we demonstrated that Dex increased the expression of TGF-beta receptor type II (TbetaRII), but not TGF-beta receptor type I (TbetaRI) in a time- and dose-dependent manner. The up-regulation of TbetaRII expression by Dex was mediated by glucocorticoid receptor and occurred at the transcriptional level. Dex also enhanced TGF-beta1 signaling and increased the expression of cyclin-dependent kinase inhibitors p15(INK4B) (p15) and p27(KIP1) (p27), which are the target genes of TGF-beta1 and have been identified as inducers of cell cycle arrest at the G1 checkpoint. The antiproliferative effect of Dex was partially blocked by anti-TbetaRII antibody, indicating that elevated TbetaRII and TGF-beta1 signaling were involved in the antiproliferative effect of Dex. Because the TGF-beta1 pathway could not fully explain the antiproliferative effect of Dex, we further examined the effects of Dex on the transcriptional activity of nuclear factor-kappaB (NF-kappaB) and the expression of IL-6 and found that Dex suppressed the transcriptional activity of NF-kappaB and IL-6 mRNA expression in PC-3 cells. These results demonstrated that glucocorticoid inhibited the proliferation of PC-3 cells not only through enhancing growth-inhibitory TGF-beta1 signaling, but also through suppressing transcriptional activities of NF-kappaB.

Glucocorticoid up-regulates transforming growth factor-beta (TGF-beta) type II receptor and enhances TGF-beta signaling in human prostate cancer PC-3 cells.

The failure of breast cancer treatment is largely due to the development of estrogen independence. Current data illustrate that Hedgehog (Hh) signaling may play an important role in breast cancer development. Here, we show that the expression of the Hh effector protein, Gli1 was significantly higher in estrogen-independent breast cancer cells than in estrogen-dependent cells. Our data showed for the first time that stable expression of Gli1 in ER positive breast cancer cell lines MCF-7 and T47D can induce estrogen-independent proliferation and promote G1/S phase transition, which associated with cyclin-Rb axi. Gli1 can also attenuate the response of proliferation to estrogenic stimulation, which was correlated with down-regulation of expression of ERalpha and PR, as well as down-regulation of transactivation of ERalpha. Our results suggest that up-regulation of Gli1 in breast cancer cells may be one of the mechanisms responsible for developing estrogen independence and this process may be regulated through down-regulation of expression and transactivation of ERalpha.

Expression of Gli1 correlates with the transition of breast cancer cells to estrogen-independent growth.

Although more than 40 beta-defensins have been identified in rat epididymis, little is known about their regulation or their relation to male infertility caused by inflammation. Using a rat model of epididymitis induced by lipopolysaccharide (LPS), we examined expression of SPAG11E (also known as Bin1b), a caput epididymis-specific beta-defensin in rat. Unlike the expression of other beta-defensins in various epithelial cells with upregulated expression after LPS stimulation, expression of SPAG11E was significantly decreased by LPS at the mRNA and protein levels. LPS treatment also significantly decreased both sperm binding to SPAG11E and sperm motility, and supplementation of the spermatozoa with recombinant SPAG11E in vitro remarkably increased both SPAG11E binding and motility of sperm. To clarify whether decreased expression is a common pattern of epididymal beta-defensins after LPS stimulation, we examined the expression of another 12 epididymal beta-defensins expressed in the caput epididymis. For nine of these beta-defensins, expression was decreased, but for the other three, expression remained unaffected. These findings demonstrate that LPS-induced epididymitis can decrease the expression of epididymal beta-defensins and that disruption of SPAG11E expression is involved in the impairment of sperm motility.

Lipopolysaccharide-induced epididymitis disrupts epididymal beta-defensin expression and inhibits sperm motility in rats.

Stomatin is an important membrane raft protein which can combine skeleton protein, some ion channel, and transporter to regulate their functions. However, until now no data on its expression and function in CNS are available. In this study, we examined distribution of stomatin in CNS of rat, and investigated the effects of hypoxia exposure and glucocorticoid on stomatin expression in cerebral cortex of rat. Immunofluorescence staining revealed a broad expression of stomatin protein in many areas of adult rat brain and spinal cord, including the ventral horn of spinal cord, causal magnocellular nucleus of hypothalamus, the V layer of the cerebral cortex, solitary nucleus, 10 and 12 nuclei, and so on. Hypoxia or ischemic hypoxia significantly up-regulated stomatin expression in cerebral cortex, and the up-regulation was independent on adrenocortical steroids since it also occurred in adrenalectomized (ADX) rats. Moreover, treatment of ADX or sham-operated rats with dexamethasone, a synthetic glucocorticoid alone could significantly stimulate expression of stomatin in lung and heart, but not in cerebral cortex. However, dexamethasone could enhance the hypoxia-stimulated expression of stomatin in cerebral cortex of ADX rats. These findings suggested that stomatin might be involved in various physiological functions and cellular events of neurons in CNS under physiological conditions and play a potential protective role under hypoxic conditions.

Distribution of stomatin expressing in the central nervous system and its up-regulation in cerebral cortex of rat by hypoxia.

In mammals, pain sensation is initiated by the detection of noxious stimuli through specialized transduction ion channels and receptors in nociceptive sensory neurons. Transient receptor potential (TRP) channels are the key sensory transducers that confer nociceptors distinct sensory modalities. However, the regulatory mechanisms about their expression are poorly defined. Here we show that the zinc-finger protein ZBTB20 regulates TRP channels expression in nociceptors. ZBTB20 is highly expressed in nociceptive sensory neurons of dorsal root ganglia. Disruption of ZBTB20 in nociceptors led to a marked decrease in the expression levels of TRPV1, TRPA1 and TRPM8 and the response of calcium flux and whole-cell currents evoked by their respective specific agonists. Phenotypically, the mice lacking ZBTB20 specifically in nociceptors showed a defect in nociception and pain sensation in response to thermal, mechanical and inflammatory stimulation. Our findings point to ZBTB20 as a critical regulator of nociception and pain sensation by modulating TRP channels expression in nociceptors.

ZBTB20 regulates nociception and pain sensation by modulating TRP channel expression in nociceptive sensory neurons.

Alpha-fetoprotein (AFP) represents a classical model system to study developmental gene regulation in mammalian cells. We previously reported that liver ZBTB20 is developmentally regulated and plays a central role in AFP postnatal repression. Here we show that ZBTB20 is a sequence-specific transcriptional repressor of AFP. By ELISA-based DNA-protein binding assay and conventional gel shift assay, we successfully identified a ZBTB20-binding site at -104/-86 of mouse AFP gene, flanked by two HNF1 sites and two C/EBP sites in the proximal promoter. Importantly, mutation of the core sequence in this site fully abolished its binding to ZBTB20 in vitro, as well as the repression of AFP promoter activity by ZBTB20. The unique ZBTB20 site was highly conserved in rat and human AFP genes, but absent in albumin genes. These help to explain the autonomous regulation of albumin and AFP genes in the liver after birth. Furthermore, we demonstrated that transcriptional repression of AFP gene by ZBTB20 was liver-specific. ZBTB20 was dispensable for AFP silencing in other tissues outside liver. Our data define a cognate ZBTB20 site in AFP promoter which mediates the postnatal repression of AFP gene in the liver.

ZBTB20 is a sequence-specific transcriptional repressor of alpha-fetoprotein gene.

The anterior pituitary harbours five distinct hormone-producing cell types, and their cellular differentiation is a highly regulated and coordinated process. Here we show that ZBTB20 is essential for anterior pituitary development and lactotrope specification in mice. In anterior pituitary, ZBTB20 is highly expressed by all the mature endocrine cell types, and to some less extent by somatolactotropes, the precursors of prolactin (PRL)-producing lactotropes. Disruption of Zbtb20 leads to anterior pituitary hypoplasia, hypopituitary dwarfism and a complete loss of mature lactotropes. In ZBTB20-null mice, although lactotrope lineage commitment is normally initiated, somatolactotropes exhibit profound defects in lineage specification and expansion. Furthermore, endogenous ZBTB20 protein binds to Prl promoter, and its knockdown decreases PRL expression and secretion in a lactotrope cell line MMQ. In addition, ZBTB20 overexpression enhances the transcriptional activity of Prl promoter in vitro. In conclusion, our findings point to ZBTB20 as a critical regulator of anterior pituitary development and lactotrope specification.

Dongmei Cao

Department of Pathophysiology

Second Military Medical University

Dissection and Coronal Slice Preparation of Developing Mouse Pituitary Gland