Transcript Zinc-Finger Proteins Required for Pairing and Synapsis

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
p610
细线期
Condensation: chromosomes
become visible
双线期
Chiasma
formation
偶线期
Pairing: telomere bouquet
终变期
粗线期
Synapsis is
complete
中期I
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
Diagram of a hermaphrodite gonad
1.Premeiotic
2.Pairing and Synapsis
3. 4. &5.pachtene
Pairing of Chromosome V Is Disrupted
in the zim-2 Mutant
Diagram of a hermaphrodite gonad
Genomic locations of FISH
Wild-type
gonad
premeiotic
Transition
zone
Pachytene region
Wild-type gonad
ZIM-2 mutation
Each chromosome relies on a specific member of the family
ZIM Proteins Bind to the Pairing Centers
of the Chromosomes They Control
Pairing Centers Associate with the Nuclear Envelope
but 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 & Review
Is the result important?
The first effort to find a family of protein
working in pairing and synapsis
Why could they succeed?
The good model animal: C.elegans
The former research : SC、PC、HIM-8
……