A Zinc-Finger Protein family Required for Pairing and Synapsis
in C. elegans
杨茹& 岳云欢
Review
• Pairing: side-by-side alignment of homologs• Synapsis: intimate association of
chromosomes specifically in the context of the synaptonemal complex (SC)
Details of Prophase I
细线期 偶线期
双线期 终变期 中期 I
粗线期Condensation: chromosomes become visible
Pairing: telomere bouquet Synapsis is complete
Chiasma formation
p610
Former investigation
The wild-type haploid karyotype of C. elegans
HIM-8 protein
• HIM:high incidence of males
• HIM-8 binds to the X chromosome pairing center and mediates chromosome-specific meiotic synapsis. Cell 123, 1051–1063. [Phillips, C.M., Wong, C., Bhalla, N., Carlton, P.M., Weiser, P.,Meneely, P.M., and Dernburg, A.F. (2005).]
The HIM-8 Protein
Localizes to the PC Region of
the X Chromoso
me
New Results
• The Gene cluster of the Family of Zinc-Finger Proteins
ZIM: zinc-finger protein in meiosis
SC incomplete : Mutations in the zim Genes Result in Meiotic Defects
Results of Mutation of Each zim Gene
Each zim Gene Is Responsible for Synapsis of Specific Autosome Pairs
1.Premeiotic 2.Pairing and Synapsis3. 4. &5.pachtene
Diagram of a hermaphrodite gonad
Pairing of Chromosome V Is Disruptedin the zim-2 Mutant
Diagram of a hermaphrodite gonadGenomic locations of FISH
Wild-type gonad
Wild-type gonad
premeioticTransition
zone Pachytene region
ZIM-2 mutation
Each chromosome relies on a specific member of the family
ZIM Proteins Bind to the Pairing Centersof the Chromosomes They Control
Pairing Centers Associate with the Nuclear Envelopebut Do Not Cluster
Multiple foci dispersed along the nuclear periphery
•Schematic of the ZIM/HIM-8 gene cluster in C. elegans, C. briggsae, and C. remanei. Predicted orthologs based on sequence comparisons are linked by gray shading.
Evolution of the ZIM/HIM-8 Protein Family
Questions
• The relationship between zim/him and telomeres?
• Recognition of the homolog chromosome
Conclusion & ReviewIs the result important?The first effort to find a family of protein
working in pairing and synapsisWhy could they succeed?The good model animal: C.elegansThe former research : SC 、 PC 、 HIM-8……