Changes In Nuclear Expression Research Articles

Changes in IL-16 Expression in the Ovary during Aging and Its Potential Consequences to Ovarian Pathology.

Aging in females is not only associated with the changes in hormonal status but is also responsible for dysregulation of immune functions in various organs including ovaries. The goal of this study was to determine whether the expression of interleukin 16 (IL-16), a proinflammatory and chemoattractant cytokine, changes during ovarian aging, to determine factors involved in such changes in IL-16 expression, and to examine if changes in IL-16 expression during aging predisposes the ovary to pathologies. Ovarian tissues from premenopausal women (30-50 years old), women at early menopause (55-59 years old), and late menopause (60-85 years old) were used. In addition, tumor tissues from patients with ovarian high-grade serous carcinoma at early stage (n = 5) were also used as reference tissue for comparing the expression of several selected markers in aging ovaries. The expression of IL-16, frequency of macrophages (a source of IL-16) and expression of microRNA (miR) 125a-5p (a regulator of IL-16 gene) were performed by immunohistochemistry, immunoblotting, and gene expression assays. In addition, we examined changes in nuclear expression of IL-16 expression with regards to exposure to follicle-stimulating hormone (FSH) by in vitro cell culture assays with human ovarian cancer cells. The frequencies of IL-16 expressing cells were significantly higher in ovarian stroma in women at early and late menopause as compared with premenopausal women (P < 0.0001). Similar patterns were also observed for macrophages. Expression of miR-125a-5p decreased significantly (P < 0.001) with the increase in IL-16 expression during aging. Furthermore, expression of nuclear IL-16 increased remarkably upon exposure to FSH. Consequently, ovarian aging is associated with increased expression of IL-16 including its nuclear fraction. Therefore, persistent high levels of FSH in postmenopausal women may be a factor for enhanced expression of IL-16. Effects of increased nuclear fraction of IL-16 need to be examined.

Functional coupling of presequence processing and degradation in human mitochondria.

The mitochondrial proteome is built and maintained mainly by import of nuclear-encoded precursor proteins. Most of these precursors use N-terminal presequences as targeting signals that are removed by mitochondrial matrix proteases. The essential mitochondrial processing protease MPP cleaves presequences after import into the organelle thereby enabling protein folding and functionality. The cleaved presequences are subsequently degraded by peptidases. While most of these processes have been discovered in yeast, characterization of the human enzymes is still scarce. As the matrix presequence peptidase PreP has been reported to play a role in Alzheimer's disease, analysis of impaired peptide turnover in human cells is of huge interest. Here, we report the characterization of HEK293T PreP knockout cells. Loss of PreP causes severe defects in oxidative phosphorylation and changes in nuclear expression of stress response marker genes. The mitochondrial defects upon lack of PreP result from the accumulation of presequence peptides that trigger feedback inhibition of MPP and accumulation of nonprocessed precursor proteins. Also, the mitochondrial intermediate peptidase MIP that cleaves eight residues from a subset of precursors after MPP processing is compromised upon loss of PreP suggesting that PreP also degrades MIP generated octapeptides. Investigation of the PrePR183Q patient mutation associated with neurological disorders revealed that the mutation destabilizes the protein making it susceptible to enhanced degradation and aggregation upon heat shock. Taken together, our data reveal a functional coupling between precursor processing by MPP and MIP and presequence degradation by PreP in human mitochondria that is crucial to maintain a functional organellar proteome.

Protective effect of ghrelin against paraquat-induced acute lung injury in mice

To measure the levels of ghrelin-induced expression or activation of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and quinone oxidoreductase 1 (NQO1) in the PQ-injured lungs of mice and to evaluate the protective effect of ghrelin against paraquat (PQ)-induced acute lung injury in mice. According to the random number table method, 50 ICR mice of clean grade were assigned to 5 groups: normal control group (n = 10), PQ group (n = 10), and ghrelin intervention groups (n = 30). For PQ group, mice were injected with a single dose of PQ (20 mg/kg, i.p.); for ghrelin intervention groups, mice were injected with a single dose of PQ (20 mg/kg, i.p.), and then ghrelin was injected at three concentrations (16.58, 33.15, and 49.73 µg/kg). Lung tissues were collected and proceeded to the following studies. HE staining was used for histopathological examination under a light microscope, and the changes in nuclear expression of Nrf2 were evaluated by Western blot. The activities of HO-1 and NQO1 were measured by ELISA. Malondialdehyde (MDA) content and MPO activity were measured by colorimetry. Another 40 mice were divided into PQ group (n = 10) and 16.58, 33.15, and 49.73 µg/kg ghrelin intervention groups (n = 10 for each); mortality and clinical manifestations were recorded within 72 h. Compared with the normal control group, the PQ group showed significant increases in nuclear protein level of Nrf2, content of MDA, and activities of HO-1, NQO1, and MPO (P < 0.05 for all). Compared with the PQ group, ghrelin treatment significantly increased the expression of Nrf2 and activities of HO-1 and NQO1 and significantly reduced the content of MDA and activity of MPO (P < 0.01 for all). Histopathological studies indicated that ghrelin showed an antioxidant property that reduced the histological changes induced by PQ in the lungs. The ghrelin intervention groups had a significantly lower mortality than the PQ group, and there was a significant difference between the high-dose ghrelin intervention group and PQ group (P < 0.05). Ghrelin can up-regulate nuclear expression of Nrf2, increase the activities of HO-1 and NQO1, and reduce the activity of MPO and content of MDA, thus protecting PQ-exposed mice from acute lung injury.

Increased Sp1 phosphorylation as a mechanism of hepatocyte growth factor (HGF/SF)-induced vascular endothelial growth factor (VEGF/VPF) transcription.

Hepatocyte growth factor (HGF/SF)-induced expression of vascular endothelial growth factor (VEGF/VPF) has been implicated in paracrine amplification of angiogenesis, contributing to angiogenic responses during inflammation, wound healing, collateral formation and tumor growth. We have shown previously that HGF/SF-mediated VEGF/VPF expression by keratinocytes is primarily dependent on transcriptional activation, and we mapped the HGF/SF-responsive element to a GC-rich region between bp -88 and -65. Sp1-like factors bind to this element constitutively; however the VEGF/VPF promoter is transactivated by HGF/SF in the absence of induced binding activity. In experimental approaches to clarify molecular mechanisms of Sp1-dependent VEGF/VPF gene transcription, neither HGF/SF-dependent changes in nuclear expression nor in relative DNA binding activity of Sp family members to the indicated element were observed. Thus, HGF/SF was hypothesized to induce VEGF/VPF gene transcription via increased transactivation activity of Sp1 owing to biochemical modification. In immunoprecipitation studies, HGF/SF was found to increase the amount of serine-phosphorylated Sp1, revealing a likely mechanism of HGF/SF-induced VEGF/VPF expression, as phosphorylation may enhance the transcriptional activity of Sp1. The contribution of different signaling molecules to HGF/SF-induced VEGF/VPF transcription was demonstrated by the use of chemical inhibition, of expression of kinase-deficient signaling proteins, and by the use of antisense oligonucleotides. Herein, we provide evidence that PI 3-kinase, MEK1/2 and PKC-zeta play a significant role in HGF/SF-induced VEGF/VPF promoter activation. Together, our results elucidate a critical pathway of paracrine amplification of angiogenesis, suggesting that HGF/SF-induced Sp1 phosphorylation may activate VEGF/VPF promoter activity that requires the contribution of distinct signaling molecules.