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Regulatory sequence analysis of semaphorin 4D 5' non-coding region.

ABSTRACT: Semaphorin 4D (Sema4D) has been proven to be one of the hypoxia effectors regulated by hypoxia inducible factor (HIF-1) in multiple cells, and play a role in angiogenesis like VEGF. However, the regulatory sequence characteristics of the Sema4D are not clarified. The possible hypoxia response element (HRE) sequences in 5' non-coding Region before ATG start codon of Sema4D were screened, followed by point mutagenesis and luciferase assay analysis. Sequencing and alignment of this region in 11 cancer cell lines and 4 normal cell lines were also performed, followed by cloning, mutation and luciferase assay analysis. The results showed that there were four possible HREs (HRE1-4) sequences in 1275bp range before ATG start codon. Among HRE1-4, HRE2 and HRE4 were functional HIF-1? binding sites. In addition, these two binding sites play different roles in the regulation of Sema4D expression in HUVEC and Caco-2 cells. There were three nucleotide variants (T471C/A600G/C862T) frequently detected in cancer cell lines. The site variation rates of T471C/A600G/C862T were 72.7%, 18.2%, and 72.7% in cancer cells respectively. Luciferase assays showed that T471C and C862T could significantly increase the expression efficiency of downstream target genes. Furthermore, secondary structure prediction showed that mutations at T471C and C862T apparently lead to change of the gene structure. Our study describes the sequence characteristics of 5' non-coding region of Sema4D, enhances our understanding of the regulatory mechanism of Sema4D and benefits the development of a possible anti-angiogenesis therapeutic strategy for malignancies.

SUBMITTER: Qiu L

PROVIDER: S-EPMC6400819 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Regulatory sequence analysis of semaphorin 4D 5' non-coding region.

Qiu Lijuan L Jiang Hongchao H Luo Jia J Xi Juemin J Wang Xiaodan X Pan Yue Y Chen Junying J Zhao Yujiao Y Sun Qiangming Q

Journal of Cancer 20190129 4

Semaphorin 4D (Sema4D) has been proven to be one of the hypoxia effectors regulated by hypoxia inducible factor (HIF-1) in multiple cells, and play a role in angiogenesis like VEGF. However, the regulatory sequence characteristics of the Sema4D are not clarified. The possible hypoxia response element (HRE) sequences in 5' non-coding Region before ATG start codon of Sema4D were screened, followed by point mutagenesis and luciferase assay analysis. Sequencing and alignment of this region in 11 can ...[more]

PMID: 30854096

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Project description:Around the fifth week after birth, the vaginal cavity in female mouse pups opens to the overlaying skin. This postnatal tissue remodeling of the genital tract occurs during puberty, and it largely depends upon hormonally induced apoptosis that mainly occurs in the epithelium at the lower part of the mouse vaginal cavity. Previously, we showed that most BALB/c mice lacking the class IV Semaphorin (Sema4D) develop imperforate vagina and hydrometrocolpos; therefore, we reasoned that the absence of Sema4D-induced apoptosis in vaginal epithelial cells may cause the imperforate vagina. Sema4D signals via the Plexin-B1 receptor; nevertheless detailed mechanisms mediating this hormonally triggered apoptosis are not fully documented. To investigate the estrogen-dependent control of Sema4D signaling during the apoptosis responsible for mouse vaginal opening, we examined structural and functional modulation of Sema4D, Plexin-B1, and signaling molecules by analyzing both wild-type and Sema4D-/- mice with or without ovariectomy. Both the release of soluble Sema4D and the conversion of Plexin-B1 by proteolytic processing in vaginal tissue peaked 5 weeks after birth of wild-type BALB/c mice at the time of vaginal opening. Estrogen supplementation of ovariectomized wild-type mice revealed that both the release of soluble Sema4D and the conversion of Plexin-B1 into an active form were estrogen-dependent and concordant with apoptosis. Estrogen supplementation of ovariectomized Sema4D-/- mice did not induce massive vaginal apoptosis in 5-week-old mice; therefore, Sema4D may be an essential apoptosis-inducing ligand that acts downstream of estrogen action in vaginal epithelium during this postnatal tissue remodeling. Analysis of ovariectomized mice also indicated that Sema4D contributed to estrogen-dependent dephosphorylation of Akt and ERK at the time of vaginal opening. Based on our results, we propose that apoptosis in vaginal epithelium during postnatal vaginal opening is induced by enhanced Sema4D signaling that is caused by estrogen-dependent structural changes of Sema4D and Plexin-B1.

Project description:OBJECTIVE:We previously discovered a role for the extracellular domain of the transmembrane protein semaphorin 4D (Sema4D) as a fast-acting, selective, and positive regulator of functional ?-aminobutyric acid (GABA)ergic synapse formation in hippocampal neuronal culture. We also demonstrated that Sema4D treatment increases inhibitory tone and suppresses hyperexcitability in an organotypic hippocampal slice culture model of epilepsy. Here, we investigate the ability of Sema4D to promote GABAergic synapse formation and suppress seizure activity in vivo in adult mice. METHODS:We performed a 3-hour, intrahippocampal infusion of Sema4D or control protein into the CA1 region of adult mice. To quantify GABAergic presynaptic bouton density, we performed immunohistochemistry on hippocampal tissue sections isolated from these animals using an antibody that specifically recognizes the glutamic acid decarboxylase isoform 65 protein (GAD65), which is localized to presynaptic GABAergic boutons. To assess seizure activity, we employed 2 in vivo mouse models of epilepsy, intravenous (iv) pentylenetetrazol (PTZ) and hippocampal electrical kindling, in the presence or absence of Sema4D treatment. We monitored seizure activity by behavioral observation or electroencephalography (EEG). To assay the persistence of the Sema4D effect, we monitored seizure activity and measured the density of GAD65-positive presynaptic boutons 3 or 48 hours after Sema4D infusion. RESULTS:Sema4D-treated mice displayed an elevated density of GABAergic presynaptic boutons juxtaposed to hippocampal pyramidal neuron cell bodies, consistent with the hypothesis that Sema4D promotes the formation of new inhibitory synapses in vivo. In addition, Sema4D acutely suppressed seizures in both the PTZ and electrical kindling models. When we introduced a 48-hour gap between Sema4D treatment and the seizure stimulus, seizure activity was indistinguishable from controls. Moreover, immunohistochemistry on brain sections or hippocampal slices isolated 3 hours, but not 48 hours, after Sema4D treatment displayed an increase in GABAergic bouton density, demonstrating temporal correlation between the effects of Sema4D on seizures and GABAergic synaptic components. SIGNIFICANCE:Our findings suggest a novel approach to treating acute seizures: harnessing synaptogenic molecules to enhance connectivity in the inhibitory network.

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Regulatory sequence analysis of semaphorin 4D 5' non-coding region.

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Regulatory sequence analysis of semaphorin 4D 5' non-coding region.

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