Lhx8 interacts with a novel germ cell-specific nuclear factor containing an Nbl1 domain in rainbow trout (Oncorhynchus mykiss).
Lhx8 is an important transcription factor that is preferentially expressed in germ cells. Lhx8 null mice are infertile due to lack of oocytes and impairment of the transition from primordial follicles to primary follicles. Lhx8 deficiency also affects the expression of many important oocyte-specific genes. In this study, we report the characterization of rainbow trout lhx8 genes and identification of a novel germ cell-specific nuclear factor that interacts with Lhx8. Two lhx8 genes, lhx8a and lhx8b, were identified, encoding proteins of 344 and 361 amino acids, respectively. The two proteins share 83% sequence identity and both transcripts are specifically expressed in the ovary. Quantitative real time PCR analysis demonstrated that both genes are expressed highly in pre-vitellogenic ovaries as well as in early stage embryos. Using a yeast two-hybrid screening system, a novel protein (Borealin-2) interacting with Lhx8 was identified. The interaction between either Lhx8a or Lhx8b and Borealin-2 was further confirmed by a bimolecular fluorescence complementation (BiFC) assay. Borealin-2 is a protein of 255 amino acids containing an Nbl1 domain, and its mRNA expression is restricted to the ovary and testis. A GFP reporter assay revealed that Borealin-2 is a nuclear protein. Collectively, results indicate that both Lhx8a and Lhx8b function through interaction with Borealin-2, which may play an important role during oogenesis and early embryogenesis in rainbow trout.
Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, West Virginia, United States of America.
Liyuan
L
Fu
Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, West Virginia, United States of America.
Prasanthi P
PP
Koganti
Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, West Virginia, United States of America.
Jian
J
Wang
Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, West Virginia, United States of America.
Lei
L
Wang
Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, West Virginia, United States of America.
Cheng-Lun
CL
Wang
Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, West Virginia, United States of America.
Jianbo
J
Yao
D000818:Animals; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005260:Female; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D060850:LIM-Homeodomain Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008297:Male; D057136:Nuclear Receptor Subfamily 6, Group A, Member 1 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017686:Oncorhynchus mykiss / Q000196:embryology / Q000235:genetics* / Q000378:metabolism*; D009866:Oogenesis / Q000235:genetics; D054730:Protein Interaction Domains and Motifs; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D059467:Transcriptome; D020798:Two-Hybrid System Techniques
D018797:Cell Cycle Proteins; D029941:Fish Proteins; D060850:LIM-Homeodomain Proteins; D057136:Nuclear Receptor Subfamily 6, Group A, Member 1; D012333:RNA, Messenger; D014157:Transcription Factors