Transcriptional regulation of connective tissue growth factor by sphingosine 1-phosphate in rat cultured mesangial cells

AbstractConnective tissue growth factor (CTGF) is induced by transforming growth factor-β (TGF-β) via Smad activation in mesangial cells. We recently reported that sphingosine 1-phosphate (S1P) induces CTGF expression in rat cultured mesangial cells. However, the mechanism by which S1P induces CTGF expression is unknown. The present study revealed that S1P-induced CTGF expression is mediated via pertussis toxin-insensitive pathways, which are involved in the activation of small GTPases of the Rho family and protein kinase C. We also showed by luciferase reporter assays and chromatin immunoprecipitation that S1P induces CTGF expression via Smad activation as TGF-β does

Altered expression of testis-specific genes, piRNAs, and transposons in the silkworm ovary masculinized by a W chromosome mutation

<p>Abstract</p> <p>Background</p> <p>In the silkworm, <it>Bombyx mori</it>, femaleness is strongly controlled by the female-specific W chromosome. Originally, it was presumed that the W chromosome encodes female-determining gene(s), accordingly called <it>Fem</it>. However, to date, neither <it>Fem </it>nor any protein-coding gene has been identified from the W chromosome. Instead, the W chromosome is occupied with numerous transposon-related sequences. Interestingly, the silkworm W chromosome is a source of female-enriched PIWI-interacting RNAs (piRNAs). piRNAs are small RNAs of 23-30 nucleotides in length, which are required for controlling transposon activity in animal gonads. A recent study has identified a novel mutant silkworm line called KG, whose mutation in the W chromosome causes severe female masculinization. However, the molecular nature of KG line has not been well characterized yet.</p> <p>Results</p> <p>Here we molecularly characterize the KG line. Genomic PCR analyses using currently available W chromosome-specific PCR markers indicated that no large deletion existed in the KG W chromosome. Genetic analyses demonstrated that sib-crosses within the KG line suppressed masculinization. Masculinization reactivated when crossing KG females with wild type males. Importantly, the KG ovaries exhibited a significantly abnormal transcriptome. First, the KG ovaries misexpressed testis-specific genes. Second, a set of female-enriched piRNAs was downregulated in the KG ovaries. Third, several transposons were overexpressed in the KG ovaries.</p> <p>Conclusions</p> <p>Collectively, the mutation in the KG W chromosome causes broadly altered expression of testis-specific genes, piRNAs, and transposons. To our knowledge, this is the first study that describes a W chromosome mutant with such an intriguing phenotype.</p

The Baculovirus Uses a Captured Host Phosphatase to Induce Enhanced Locomotory Activity in Host Caterpillars

The baculovirus is a classic example of a parasite that alters the behavior or physiology of its host so that progeny transmission is maximized. Baculoviruses do this by inducing enhanced locomotory activity (ELA) that causes the host caterpillars to climb to the upper foliage of plants. We previously reported that this behavior is not induced in silkworms that are infected with a mutant baculovirus lacking its protein tyrosine phosphatase (ptp) gene, a gene likely captured from an ancestral host. Here we show that the product of the ptp gene, PTP, associates with baculovirus ORF1629 as a virion structural protein, but surprisingly phosphatase activity associated with PTP was not required for the induction of ELA. Interestingly, the ptp knockout baculovirus showed significantly reduced infectivity of larval brain tissues. Collectively, we show that the modern baculovirus uses the host-derived phosphatase to establish adequate infection for ELA as a virion-associated structural protein rather than as an enzyme

Precocious Metamorphosis in the Juvenile Hormone–Deficient Mutant of the Silkworm, Bombyx mori

Insect molting and metamorphosis are intricately governed by two hormones, ecdysteroids and juvenile hormones (JHs). JHs prevent precocious metamorphosis and allow the larva to undergo multiple rounds of molting until it attains the proper size for metamorphosis. In the silkworm, Bombyx mori, several “moltinism” mutations have been identified that exhibit variations in the number of larval molts; however, none of them have been characterized molecularly. Here we report the identification and characterization of the gene responsible for the dimolting (mod) mutant that undergoes precocious metamorphosis with fewer larval–larval molts. We show that the mod mutation results in complete loss of JHs in the larval hemolymph and that the mutant phenotype can be rescued by topical application of a JH analog. We performed positional cloning of mod and found a null mutation in the cytochrome P450 gene CYP15C1 in the mod allele. We also demonstrated that CYP15C1 is specifically expressed in the corpus allatum, an endocrine organ that synthesizes and secretes JHs. Furthermore, a biochemical experiment showed that CYP15C1 epoxidizes farnesoic acid to JH acid in a highly stereospecific manner. Precocious metamorphosis of mod larvae was rescued when the wild-type allele of CYP15C1 was expressed in transgenic mod larvae using the GAL4/UAS system. Our data therefore reveal that CYP15C1 is the gene responsible for the mod mutation and is essential for JH biosynthesis. Remarkably, precocious larval–pupal transition in mod larvae does not occur in the first or second instar, suggesting that authentic epoxidized JHs are not essential in very young larvae of B. mori. Our identification of a JH–deficient mutant in this model insect will lead to a greater understanding of the molecular basis of the hormonal control of development and metamorphosis

バキュロウイルスが持つbv/odv-e26遺伝子は宿主チョウ目昆虫の行動を操作するためにウイルス感染を最適化する因子である

Dataset for the manuscript entitled "Baculovirus bv/odv-e26 is required for host behavioral manipulation by optimizing viral virulence to lepidopteran hosts"1.

Is the expression of sense and antisense transgenes really sufficient for artificial piRNA production?

SummaryAnimals have evolved an elegant defense system against a diverse range of selfish elements such as transposons. In animal germ line cells, PIWI proteins and small RNAs associated with PIWI proteins (piRNAs) are at the heart of this defense system. piRNAs are 23–30-nt-long small RNAs that act as sequence-specific guides for PIWI proteins. PIWI proteins possess a slicer activity that is guided by piRNAs; the PIWI–piRNA complex thus silences transposon activity by cleaving transposon RNAs [1]. At present, how de novo piRNA production occurs against a new non-self element is largely unknown. A recent study by Itou et al. [2] using reporter transgenic mice concluded that the concomitant expression of sense and antisense RNA transcripts is sufficient for piRNA production. Our bioinformatic analysis using the same piRNA datasets, however, demonstrates that the introduction of the antisense reporter construct alone produces transgene-derived piRNAs, which is inconsistent with a part of the conclusions of Itou et al. [2]

バキュロウイルスの多角体形成機構に関する分子生物学的研究

University of Tokyo (東京大学