The lue1 mutant was previously isolated in a bio-imaging screen for Arabidopsis mutants exhibiting inappropriate regulation of an AtGA20ox1 promoter-luciferase reporter fusion. Here we show that lue1 is allelic to fra2, bot1 and erh3, and encodes a truncated katanin-like microtubulesevering protein (AtKSS). Complementation of lue1 with the wild-type AtKSS gene restored both wild-type stature and luciferase reporter levels. Hormonal responses of lue1 to ethylene and gibberellins revealed inappropriate cortical microtubule reorientation during cell growth. Moreover, a fusion between the AtKSS protein and GFP decorated cortical microtubules. A yeast two-hybrid screen with AtKSS as the bait identified proteins related to those involved in microtubule processing, including a katanin p80 subunit and a kinesin ortholog. These results indicate that AtKSS is involved in microtubule dynamics in response to plant hormones.

We identified a recessive, brassinolide-insensitive mutant caused by a deletion allele (bri1-201) of the brassinosteroid (BR) receptor BRI1. The bri1-201 mutant displayed altered expression levels of genes differentially regulated by gibberellin (GA). RNA-blot analysis revealed that BR and GA antagonistically regulate the accumulation of mRNAs of the GA-responsive GASA1 gene, as well as the GA-repressible GA5 gene. Expression studies with cycloheximide indicated that the antagonistic effects of GA and BR on GA5 require de novo protein synthesis. Reporter transgene analyses and RNA-blot analysis showed that BR and GA modulate GA5 expression, at least in part, at the transcriptional level, and that the signals are independent and subtractive.

The enzyme ACC oxidase catalyses the last step of ethylene biosynthesis in plants, converting 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene. We have previously described the isolation and characterization of a cDNA clone (pMEL1) encoding an ACC oxidase homolog from melon (Cucumis melo L.). Here we report the isolation and characterization of three genomic clones, corresponding to three putative members of the ACC oxidase gene family in melon. All are transcriptionally active. The sequences of these genes have been determined. One genomic clone (CM-ACO1), corresponding to the cDNA previously isolated, presents a coding region interrupted by three introns. Its transcription initiation site has been defined with RNA from ripe fruit and ethylene-treated leaves. The other two genes (CM-ACO2, CM-ACO3) have only two introns, at positions identical to their counterparts in CM-ACO1. The degree of DNA homology in the coding regions of CM-ACO2 and CM-ACO3 relative to CM-ACO1 is 59% and 75%, respectively. CM-ACO2 and CM-ACO3 are 59% homologous in their coding regions. These three genes have close homology to PH-ACO3, a member of the ACC oxidase multigene family of petunia. The predicted amino acid sequences of CM-ACO1 and CM-ACO3 are 77% to 81% identical to those encoded by the tomato and petunia genes, while the deduced amino acid sequence of CM-ACO2 shows only 42% to 45% homology. RT-PCR analysis using gene-specific primers shows that the three genes are differentially expressed during development, ethylene treatment and wounding. CM-ACO1 is induced in ripe fruit and in response to wounding and to ethylene treatment in leaves. CM-ACO2 is detectable at low level in etiolated hypocotyls. CM-ACO3 is expressed in flowers and is not induced by any of the stimuli tested.

Activation of the receptor tyrosine kinase MET is associated with poor clinical outcome in certain cancers. To target MET more effectively, we developed an antagonistic antibody mixture, Sym015, consisting of two humanized mAbs directed against nonoverlapping epitopes of MET. We screened a large panel of well-annotated human cancer cell lines and identified a subset with highly elevated MET expression. In particular, cell lines of lung cancer and gastric cancer origin demonstrated high MET expression and activation, and Sym015 triggered degradation of MET and significantly inhibited growth of these cell lines. Next, we tested Sym015 in patient- and cell line-derived xenograft models with high MET expression and/or exon 14 skipping alterations, and in models harboring amplification as a mechanism of resistance to EGFR-targeting agents. Sym015 effectively inhibited tumor growth in all these models and was superior to an analogue of emibetuzumab, a monoclonal IgG4 antibody against MET currently in clinical development. Sym015 also induced antibody-dependent cellular cytotoxicity (ADCC) , suggesting that secondary effector functions contribute to the efficacy of Sym015.Retrospectively, all responsive, high MET-expressing models were scored as highly-amplified by hybridization, pointing to amplification as a predictive biomarker for efficacy. Preclinical toxicology studies in monkeys showed that Sym015 was well tolerated, with a pharmacokinetic profile supporting administration of Sym015 every second or third week in humans. The preclinical efficacy and safety data provide a clear rationale for the ongoing clinical studies of Sym015 in patients with -amplified tumors..

The enzyme ACC oxidase catalyses the last step of ethylene biosynthesis in plants, converting 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene. We have previously described the isolation and characterization of a cDNA clone (pMEL1) encoding an ACC oxidase homolog from melon (Cucumis melo L.). Here we report the isolation and characterization of three genomic clones, corresponding to three putative members of the ACC oxidase gene family in melon. All are transcriptionally active. The sequences of these genes have been determined. One genomic clone (CM-ACO1), corresponding to the cDNA previously isolated, presents a coding region interrupted by three introns. Its transcription initiation site has been defined with RNA from ripe fruit and ethylene-treated leaves. The other two genes (CM-ACO2, CM-ACO3) have only two introns, at positions identical to their counterparts in CM-ACO1. The degree of DNA homology in the coding regions of CM-ACO2 and CM-ACO3 relative to CM-ACO1 is 59% and 75%, respectively. CM-ACO2 and CM-ACO3 are 59% homologous in their coding regions. These three genes have close homology to PH-ACO3, a member of the ACC oxidase multigene family of petunia. The predicted amino acid sequences of CM-ACO1 and CM-ACO3 are 77% to 81% identical to those encoded by the tomato and petunia genes, while the deduced amino acid sequence of CM-ACO2 shows only 42% to 45% homology. RT-PCR analysis using gene-specific primers shows that the three genes are differentially expressed during development, ethylene treatment and wounding. CM-ACO1 is induced in ripe fruit and in response to wounding and to ethylene treatment in leaves. CM-ACO2 is detectable at low level in etiolated hypocotyls. CM-ACO3 is expressed in flowers and is not induced by any of the stimuli tested.