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Updated: Aug 20, 2026
Functional Cloning Using a Xenopus Oocyte Expression System
Published on: January 30, 2016
Molecular cloning and expression of cDNA coding for four spliced isoforms of casein kinase Ialpha in goldfish oocytes
Ryo Horiguchi1, Mika Tokumoto, Yoshitaka Nagahama
1Department of Molecular Biomechanics, Graduate University for Advanced Studies, Okazaki, 444-8585, Japan.
Abstract:
Casein kinase I (CKI) is a member of the serine/threonine protein kinases and located in a separate group within the superfamily of eukaryotic protein kinases. CKI isoforms regulate several checkpoints of the cell cycle and meiosis. In higher eukaryotes, CKIalpha has four isoforms produced through the alternative splicing of two short inserts. Here, we report the cloning, sequencing and expression of four alternatively spliced isoforms of CKIalpha from goldfish ovary. The cloned cDNAs were 2099-3002-bp long and classified as CKIalpha, CKIalphaS, CKIalphaL and CKIalphaLS. It was revealed that two major (3.0 and 2.0 kb) messages were strongly expressed in the ovary. Four isoforms are expressed in previtellogenic to vitellogenic oocytes. In the huge nucleus of the oocyte, referred to as the germinal vesicle, CKIalphaS is dominant and CKIalphaL is expressed at a detectable level. Immunoblot analysis revealed that CKIalpha and CKIalphaS are major products in both immature and mature oocytes. These two isoforms were expressed in a tissue-dependent manner.
Insights
This study identifies and characterizes four casein kinase I alpha (CKIα) isoforms in goldfish ovaries. These isoforms play distinct roles in oocyte development and are expressed in a tissue-specific manner.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Casein kinase I (CKI) is a crucial serine/threonine protein kinase family involved in eukaryotic cell cycle regulation.
- CKIalpha (CKIα) isoforms are known to regulate cell cycle and meiosis checkpoints.
- Alternative splicing in higher eukaryotes generates multiple CKIα isoforms.
Purpose of the Study:
- To clone, sequence, and analyze the expression of alternatively spliced CKIα isoforms from goldfish ovaries.
- To investigate the specific roles and expression patterns of CKIα isoforms during oocyte maturation.
Main Methods:
- Cloning and sequencing of complementary DNAs (cDNAs) encoding CKIα isoforms.
- Messenger RNA (mRNA) expression analysis using Northern blotting.
- Protein expression analysis via immunoblotting.
Main Results:
- Four distinct CKIα isoforms (CKIα, CKIαS, CKIαL, and CKIαLS) were identified in goldfish ovary.
- Two major mRNA transcripts (3.0 and 2.0 kb) were highly expressed in the ovary.
- CKIαS was dominant in the germinal vesicle of oocytes, while CKIα and CKIαS were major protein products in both immature and mature oocytes.
- Isoform expression demonstrated tissue-specific patterns.
Conclusions:
- The study elucidates the diversity of CKIα isoforms in goldfish oogenesis.
- Differential expression of CKIα isoforms suggests specialized functions in oocyte development and cell cycle regulation.
- Tissue-specific expression highlights the complex regulatory mechanisms of CKIα in goldfish reproduction.
