High impact information on MSI1

• In Arabidopsis thaliana, the three CAF-1 subunits are encoded by FAS1, FAS2 and, most likely, MSI1, respectively [1].
• Further more, msi1 mutant gametophytes initiate endosperm development in the absence of fertilization at a high penetrance [2].
• In contrast with msi1, supernumerary nuclei in rbr1 female gametophytes originate mainly from the endosperm precursor lineage but do not express an endosperm fate marker [3].
• As msi1 autonomous seeds mostly contain autonomous endosperm, our results indicate that the developing endosperm is sufficient to enhance cell proliferation and differentiation in the seed coat [3].
• These results reveal that the functions of FAS1, FAS2 and MSI1 are not restricted to meristems, but are also needed to control genome replication at multiple steps of development [4].

Biological context of MSI1

• We have cloned the MEDICIS gene and show that it encodes the Arabidopsis homologue of the yeast WD40 domain protein MULTICOPY SUPRESSOR OF IRA (MSI1) [5].
• We report that single mutations in the gene MULTICOPY SUPPRESSOR OF IRA 1 (MSI1) are able to initiate parthenogenetic development of the embryo in Arabidopsis thaliana from eggs cells produced by meiosis [6].
• MSI1 is needed to establish epigenetic H3K4 di-methylation and H3K9 acetylation marks in SOC1 chromatin [7].
• Strong ectopic expression of AtMSI1 produced no visible altered phenotype, but reduction of AtMSI1 dramatically affected development [8].
• Efficient formation of heterochromatin, but not methylation of centromeric DNA repeats, depends on AtMSI1 presence demonstrating a key role of AtMSI1 in maintenance of chromatin structure [8].

Other interactions of MSI1

• However, MSI1 function is independent of FLC [7].

References