An insulin-like growth factor homologue of Singapore grouper iridovirus modulates cell proliferation, apoptosis and enhances viral replication.
Insulin-like growth factors (IGFs) play crucial roles in regulating cell differentiation, proliferation and apoptosis. In this study, a novel IGF homologue gene (IGF-like) encoded by Singapore grouper iridovirus (SGIV) ORF062R (termed SGIV-IGF), was cloned and characterized. The coding region of SGIV-IGF is 771 bp in length, with a variable number of tandem repeats (VNTR) locus at the 3'-end. We cloned one isoform of this novel gene, 582 bp in length, containing the predicted IGF domain and 3.6 copy numbers of the 27 bp repeat unit. SGIV-IGF was an early transcribed gene during viral infection, and SGIV-IGF was distributed predominantly in the cytoplasm with a diffused granular appearance. Intriguingly, overexpression of SGIV-IGF was able to promote the growth of grouper embryonic cells (GP cells) by promoting G1/S phase transition, which was at least partially dependent on its 3'-end VNTR locus. Furthermore, viral titre assay and real-time quantitative PCR (RT-qPCR) analysis proved that SGIV-IGF could promote SGIV replication in grouper cells. In addition, overexpression of SGIV-IGF mildly facilitated apoptosis in SGIV-infected non-host fathead minnow (FHM) cells. Together, our study demonstrated a novel functional gene of SGIV which may regulate viral replication and cellular processes through multiple mechanisms that appear to be cell type-dependent.
Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China.
Yang
Y
Yan
Department of Medicine, University of Alabama at Birmingham, 901 19th Street South, Birmingham, AL 35294, USA.
Huachun
H
Cui
University of Chinese Academy of Sciences, Beijing, PR China.|Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China.
Chuanyu
C
Guo
Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou 510080, PR China.
Jun
J
Li
Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China.
Xiaohong
X
Huang
Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China.
Jingguang
J
Wei
Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China.
Qiwei
Q
Qin
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D020869:Gene Expression Profiling; D017994:Iridovirus / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D010473:Perciformes / Q000196:embryology / Q000821:virology*; D017995:Ranavirus / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012846:Singapore; D013002:Somatomedins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D014779:Virus Replication / Q000187:drug effects*
D013002:Somatomedins; D014764:Viral Proteins