Disease relevance of BIN2

• We have isolated two new BR-insensitive mutants (dwarf12-1D and dwf12-2D) after screening Arabidopsis ethyl methanesulfonate mutant populations. dwf12 mutants displayed the characteristic morphology of previously reported BR dwarfs including short stature, short round leaves, infertility, and abnormal de-etiolation [1].

High impact information on BIN2

• BES1 is phosphorylated and appears to be destabilized by the glycogen synthase kinase-3 (GSK-3) BIN2, a negative regulator of the BR pathway [2].
• Here, we describe four recessive alleles of the UCU2 gene, whose homozygotes display helical rotation of several organs in addition to other phenotypic traits shared with ucu1 mutants [3].
• We propose that BES1/BZR1 are two nuclear components of BR signaling that are negatively regulated by BIN2 through a phosphorylation-initiated process [4].
• It was proposed that BR signals, perceived by a membrane BR receptor complex that contains the leucine (Leu)-rich repeat receptor-like kinase BRI1, inactivate BIN2 to relieve its inhibitory effect on unknown downstream BR-signaling components [4].
• In addition, dwf12 mutants exhibited several unique phenotypes, including severe downward curling of the leaves [1].

Biological context of BIN2

• Genetic analysis of the bin2 (BR-INSENSITIVE 2) mutant indicated that the BR-insensitive dwarf phenotype was due to a semidominant mutation in the BIN2 gene that mapped to the middle of chromosome IV between the markers CH42 and AG [5].
• A gene dosage experiment using triploid plants suggested that the bin2 phenotypes were likely caused by either neomorphic or hypermorphic gain-of-function mutations in the BIN2 gene [5].
• In this paper we report the characterization of three novel members of the Arabidopsis shaggy-related protein kinase (ASK) multigene family, named ASKdzeta (ASKzeta), ASKetha (ASKeta) and ASKiota (ASKiota) [6].
• Sequence analyses indicate that the tetraploid cotton genome includes four genes with strong sequence similarity to BIN 2 [7].

Associations of BIN2 with chemical compounds

• We have positionally cloned the UCU1 gene, which encodes an AtSK protein involved in the cross-talk between auxin and brassinosteroid signaling pathways, as indicated by the responses of ucu1 mutants to plant hormones and the phenotypes of double mutants involving ucu1 alleles [8].
• Lithium chloride treatment was able to suppress the gain-of-function bin2-1 mutation but had a much weaker effect on a strong BR receptor mutant, suggesting the presence of a BIN2-independent regulatory step downstream of BR receptor activation [9].

Other interactions of BIN2

• BES1 and its closest homolog, BZR1, which was also uncovered as a potential BR-signaling protein, display specific interactions with BIN2 in yeast [4].
• In addition to the BR-insensitive dwarf phenotype, bin2 mutants exhibited BR insensitivity when assayed for root growth inhibition and feedback inhibition of CPD gene expression [5].

References