Modulate Host Gene Expression Research Articles

Differential expression of growth factors at the cellular level in virus-infected brain.

The contribution of host factors to rabies virus (RV) transcription/replication and axonal/transsynaptic spread is largely unknown. We previously identified several host genes that are up-regulated in the mouse brain during RV infection, including neuroleukin, which is involved in neuronal growth and survival, cell motility, and differentiation, and fibroblast growth factor homologous factor 4 (FHF4), which has been implicated in limb and nervous system development. In this study, we used real-time quantitative RT-PCR to assess the expression of mRNAs specific for neuroleukin, the two isoforms of FHF4 (FHF4-1a and -1b) encoded by the FHF4 gene, and N protein of RV in neurons and astrocytes isolated by laser capture microdissection from mouse brains infected with the laboratory-adapted RV strain CVS-N2c or with a street RV of silver-haired bat origin. Differences in the gene expression patterns suggest that the capacity of RV strains to infect nonneuronal cells and differentially modulate host gene expression may be important in virus replication and spread in the CNS.

Cloning of a tobacco cDNA coding for a putative transcriptional coactivator MBF1 that interacts with the tomato mosaic virus movement protein

Viral movement through plasmodesmata in host plants depends on the interaction between virus-encoded movement protein (MP) and host proteins. To search for MP-interacting protein (MIP), far-western screening of a tobacco cDNA library was carried out using a recombinant MP of tomato mosaic virus (ToMV) as a probe. One of the positive cDNA clones, designated MIP204, was highly homologous to a class of transcriptional coactivators commonly referred to as multiprotein bridging factor 1 (MBF1). ToMV MP could also bind to the Arabidopsis homologues of MBF1. The recombinant MIP204 bound to MPs of ToMV and a crucifer tobamovirus CTMV-W, but not of cucumber mosaic virus. MPs of ToMV and the related virus may interact with MBF1-like proteins to modulate host gene expression.

Modulation of Host Gene Expression during Initiation and Early Growth of Nodules in Cowpea, Vigna unguiculata (L.) Walp.

Inoculation of 2-day-old cowpea (Vigna unguiculata [L.] Walp.) seedlings with Rhizobium fredii USDA257 results in proficient nodulation of the tap root. The most abundant nodulation occurs in a region roughly corresponding to the position of the root tip at the time of inoculation. We have examined plant gene expression in this region, after inoculation with either USDA257 or a nonnodulating mutant, 257B3. After isolation of mRNA and in vitro translation, the protein products were separated by two-dimensional gel electrophoresis. Seven proteins are induced within 2.5 days after inoculation with USDA257. One additional induced protein is detectable by 3.5 days after inoculation, and three more appear by day 6. Three of the proteins that are differentially expressed at 2.5 and 3.5 days after inoculation are produced at equivalent levels after 6 days, indicating transient induction of these genes during early stages of nodule development. Several proteins were more abundant in translations of mRNA from roots that had been inoculated with the nonnodulating mutant. This was particularly true after 6 days, when nine proteins were in this class. Thus, altered plant gene expression in carefully selected, highly responsive tissue can be detected 2 days before emerging nodules are visible on the roots, and 6 to 7 days before acetylene reduction is detectable. Additionally, comparisons of ionically bound cell wall proteins isolated 6 days after inoculation revealed four that were unique to nodulating roots, suggesting that some of the nodulation-induced genes may code for structural proteins.

The nucleotide sequence of the Escherichia coli K12 nusB (groNB) gene.

The nusB (groNB) gene product of Escherichia coli plays a pivotal role in allowing bacteriophage lambda N protein to function as an antiterminator of mRNA transcription and in modulating host gene expression. In addition it is essential for bacterial viability since mutations in it result in a cold-sensitivity phenotype for growth. We have previously cloned the nusB gene and shown it to code for a 14,500-Mr protein. Here we present the primary DNA sequence of the nusB gene. From the sequence we deduce that it codes for a slightly basic protein (21 basic as opposed to 20 acidic amino acids) composed of 139 amino acids with a cumulative 15,689-Mr. The predicted N-terminal amino acid sequence as well as the overall amino acid composition agrees well with that of the purified protein.