bEndogenous retroviruses (ERVs) comprise a significant percentage of the mammalian genome, and it is poorly understood whether they will remain as inactive genomes or emerge as infectious retroviruses. Although several types of ERVs are present in domestic cats, infectious ERVs have not been demonstrated. Here, we report a previously uncharacterized class of endogenous gammaretroviruses, termed ERV-DCs, that is present and hereditary in the domestic cat genome. We have characterized a subset of ERV-DC proviral clones, which are numbered according to their genomic insertions. One of these, ERV-DC10, located in the q12-q21 region on chromosome C1, is an infectious gammaretrovirus capable of infecting a broad range of cells, including human. Our studies indicate that ERV-DC10 entered the genome of domestic cats in the recent past and appeared to translocate to or reintegrate at a distinct locus as infectious ERV-DC18. Insertional polymorphism analysis revealed that 92 of 244 domestic cats had ERV-DC10 on a homozygous or heterozygous locus. ERV-DC-like sequences were found in primate and rodent genomes, suggesting that these ERVs, and recombinant viruses such as RD-114 and BaEV, originated from an ancestor of ERV-DC. We also found that a novel recombinant virus, feline leukemia virus subgroup D (FeLV-D), was generated by ERV-DC env transduction into feline leukemia virus in domestic cats. Our results indicate that ERV-DCs behave as donors and/or acceptors in the generation of infectious, recombinant viruses. The presence of such infectious endogenous retroviruses, which could be harmful or beneficial to the host, may affect veterinary medicine and public health.

The DELLA protein SLENDER RICE1 (SLR1) is a repressor of gibberellin (GA) signaling in rice (Oryza sativa), and most of the GA-associated responses are induced upon SLR1 degradation. It is assumed that interaction between GIBBERELLIN INSENSITIVE DWARF1 (GID1) and the N-terminal DELLA/TVHYNP motif of SLR1 triggers F-box protein GID2-mediated SLR1 degradation. We identified a semidominant dwarf mutant, Slr1-d4, which contains a mutation in the region encoding the C-terminal GRAS domain of SLR1 (SLR1 G576V ). The GA-dependent degradation of SLR1 G576V was reduced in Slr1-d4, and compared with SLR1, SLR1 G576V showed reduced interaction with GID1 and almost none with GID2 when tested in yeast cells. Surface plasmon resonance of GID1-SLR1 and GID1-SLR1 G576V interactions revealed that the GRAS domain of SLR1 functions to stabilize the GID1-SLR1 interaction by reducing its dissociation rate and that the G576V substitution in SLR1 diminishes this stability. These results suggest that the stable interaction of GID1-SLR1 through the GRAS domain is essential for the recognition of SLR1 by GID2. We propose that when the DELLA/TVHYNP motif of SLR1 binds with GID1, it enables the GRAS domain of SLR1 to interact with GID1 and that the stable GID1-SLR1 complex is efficiently recognized by GID2.

DELLA protein is a key negative regulator of gibberellin (GA) signaling. Although how DELLA regulates downstream gene expression remains unclear, DELLA has been proposed to function as a transcriptional activator. However, because DELLA lacks a DNAbinding domain, intermediate protein(s) mediating the DELLA/DNA interaction are believed to be necessary for activating DELLA target genes. Here, using yeast hybrid screenings, we identified five members of INDETERMINATE DOMAIN (IDD) protein family which bind physically to both DELLA and the promoter sequence of the GA-positive regulator SCARECROW-LIKE 3 (SCL3), which previously was characterized as a DELLA direct target gene. Transient assays using Arabidopsis protoplasts demonstrated that a luciferase reporter controlled by the SCL3 promoter was additively transactivated by REPRESSOR of ga1-3 (RGA) and IDDs. Phenotypic analysis of transgenic plants expressing AtIDD3 (one of the 16 IDDs in the Arabidopsis genome) fused with the plant-specific repression domain (SRDX) supported the possibility that AtIDD3 is positively involved in GA signaling. In addition, we found that SCL3 protein also interacts with IDDs, resulting in the suppression of its target gene expression. In this context, DELLA and SCL3 interact competitively with IDD proteins to regulate downstream gene expression. These results suggest that the coregulators DELLA and SCL3, using IDDs as transcriptional scaffolds for DNA binding, antagonistically regulate the expression of their downstream targets to control the GA signaling pathway.transcription factor | gibberellin feedback regulation | coactivator/corepressor exchange regulation system G ibberellins (GAs) are diterpene phytohormones that regulate many cellular and developmental events such as cell elongation, leaf expansion, flowering, pollen maturation, and the transition from vegetative growth to flowering (1-4). Several protein factors involved in GA signaling have been identified. Among these, DELLA protein is a key player in the regulation of GA responses. DELLA proteins are characterized by a DELLA/TVHYNP motif at the N terminus and a GRAS domain [named after its first three members: GA INSENSITIVE (GAI), REPRESSOR of ga1-3 (RGA), and SCARECROW (SCR)] at the C terminus, placing DELLAs within the GRAS family of transcriptional regulators. GRAS-domain transcription factors have diverse functions in growth and development. Recent intensive studies revealed how GA is perceived by the GA receptor GIBBERELLIN INSENSITIVE DWARF1 (GID1) and how the perceived GA signal is transmitted to DELLA. By binding to active GAs, GID1 acquires the ability to interact with DELLA, allowing further interaction with an F box protein, SLEEPY1/GID2. DELLA is polyubiquitinated by E3 ubiquitin-ligase SCF SLY1/GID2 and finally is degraded through the 26S proteasome. However, how DELLA regulates downstream gene expression in GA signaling has remained unclear.In Arabidopsis, five DELLA genes have been identified; GAI, RGA, and three RGA-LIKE proteins (RGL1, RGL2, and RGL3) (1-...

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Background: Systemic corticosteroids are one of the most commonly used therapeutic modalities for patients with extensive alopecia areata (AA), although they entail several drawbacks. Objective: To determine the best modality for systemic corticosteroid use in terms of their efficacy, relapse rate, and side effects. Methods: Fifty-one patients with single or multiple AA (AA/multiplex) and 38 patients with alopecia totalis or AA universalis (AA totalis/universalis) were enrolled in this open study. They were randomly divided into three groups depending on the time of their initial visit. They were administered (1) oral dexamethasone (Dex) 0.5 mg/day for 6 months (Dex group), (2) intramuscular triamcinolone acetonide (imTA) 40 mg once a month for 6 months followed by 40 mg once every 1.5 months for 1 year (imTA group), and (3) pulse therapy (PT) using oral predonine 80 mg for 3 consecutive days once every 3 months (PT group). After the treatment, each treatment modality was evaluated by the response rate, relapse rate, and side effect profile. Results: The response rate of AA/multiplex was significantly better in the imTA group than in the Dex group. The overall relapse rate and that of AA totalis/universalis were significantly better in the PT group than in the Dex group. Dysmenorrhea was the most common and problematic side effect. Impairment of the adrenocortical reserve was seen in 7% of the PT group and 23% of the imTA group, which was recov ered without any further medical treatment. Conclusion: imTA or pulse therapy is effective for AA and has an acceptable level of side effects. The development of a new strategy to reduce the relapse rate is needed.