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Identification and developmental expression of cyclin-dependent kinase 4 gene in Xenopus laevis
C Goisset1, J C Boucaut, D L Shi
1Laboratoire de Biologie Moléculaire et Cellulaire du Développement, CNRS URA 1135, Université P. et M. Curie, Paris, France.
Abstract:
Cyclin-dependent kinases (CDKs) are a family of serine/threonine protein kinases which play a pivotal role in the eucaryote cell cycle regulation. We have identified the Xenopus homologue of mammalian CDK4 (XCDK4). The protein sequence of XCDK4 has 78 and 77% overall identity to human and mouse CDK4, respectively. Northern blot analysis revealed a single transcript of approximately 4.5 kb present at various stages. XCDK4 transcripts show very dynamic expression during early development. The level of expression is higher during cleavage and gastrulation. In situ hybridization analysis revealed that the transcripts are enriched in the dorsal mesoderm at the beginning of gastrulation, then extend to both the lateral and ventral mesoderm. At the end of gastrulation, XCDK4 transcripts are mainly distributed in the blastoporal region and in the anterior neural fold. During neurulation they become restricted to optic vesicles and to neural crest cells organizing the branchial arches. As development proceeds, XCDK4 transcripts are highly expressed in the branchial arches. At late tail-bud stages, XCDK4 transcripts are also detected in ventral hematopoietic precursor cells. Therefore, this analysis clearly shows that XCDK4 has a regionalized expression during Xenopus embryogenesis.
Insights
Researchers identified Xenopus CDK4 (XCDK4), a key cell cycle regulator. Its dynamic, regionalized expression during embryonic development suggests crucial roles in Xenopus embryogenesis.
Area of Science:
- Developmental Biology
- Molecular Biology
- Cell Cycle Regulation
Background:
- Cyclin-dependent kinases (CDKs) are essential serine/threonine protein kinases regulating the eukaryotic cell cycle.
- CDK4 is a critical regulator involved in cell cycle progression.
Purpose of the Study:
- To identify and characterize the Xenopus homologue of CDK4 (XCDK4).
- To investigate the expression pattern of XCDK4 during early Xenopus development.
Main Methods:
- Sequence analysis to determine XCDK4 homology to mammalian CDK4.
- Northern blot analysis to detect XCDK4 transcript size and abundance.
- In situ hybridization to map XCDK4 transcript localization during embryogenesis.
Main Results:
- Xenopus CDK4 (XCDK4) shares high sequence identity with mammalian CDK4.
- XCDK4 exhibits dynamic and spatially restricted expression throughout Xenopus embryogenesis.
- Transcripts are notably abundant during cleavage and gastrulation, with specific localization in dorsal mesoderm, neural folds, optic vesicles, branchial arches, and hematopoietic precursors.
Conclusions:
- XCDK4 plays a significant role in regulating cell cycle progression during Xenopus development.
- The regionalized expression pattern indicates specific functions in the development of various embryonic tissues, including the nervous system and hematopoietic system.