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DTSTAMP:20260424T143401Z
UID:1746442800@ist.ac.at
DTSTART:20250505T130000
DTEND:20250505T140000
DESCRIPTION:Speaker: Syamala Inumella\nhosted by Mario de Bono\nAbstract: A
 s root epidermal cells progress from a phase of elongation to differentiat
 ion\, their cortical microtubule (MT) arrays exhibit a transversal-to-long
 itudinal reorientation. The hormone cytokinin\, a key regulator of root de
 velopment\, facilitates these cytoskeletal changes. However\, the molecula
 r mechanisms underlying hormone-mediated MT reorientation during root deve
 lopment are still unknown. Here\, we find that MT reorientation in root ce
 lls differs from the existing model in hypocotyl cells\, as it does not re
 ly on the rescue of the new MT plus-end formed by severing. We show that c
 ytokinin facilitates MT array reorganization during cell differentiation b
 y promoting katanin’s (KTN1) severing activity\, and by modulating KTN1
 ’s association with microtubules. Additionally\, cytokinin regulates SPI
 RAL2 (SPR2) in a phosphorylation-dependent manner\, directing its localiza
 tion to\, and stabilization of\, the new MT minus-end created by katanin-m
 ediated severing at crossovers. Notably\, our findings suggest that dynami
 c and reversible phosphorylation at S579 of SPR2 is crucial for the proper
  functioning of the MT severing machinery. Finally\, we identify MAP65-1 a
 nd CLASP as additional targets of cytokinin phosphoregulation. Cytokinin t
 reatment decreases MT-MAP65-1 association in elongating cells\, likely to 
 expose MTs to KTN1-mediated severing\, whereas it increases MT-CLASP assoc
 iation to stabilize the growing plus-end. In this way\, cytokinin drives M
 T reorganization during cell development by simultaneously modulating seve
 ral microtubule-associated proteins. These results reveal key molecular pl
 ayers in hormone-mediated cytoskeletal regulation\, and highlight protein 
 phosphorylation as a powerful tool during this process.
LOCATION:Moonstone Bldg / Ground floor / Seminar Room F (I24.EG.030f ) and 
 Zoom\, ISTA
ORGANIZER:
SUMMARY:Syamala Inumella: Molecular Mechanisms of Microtubule Reorganizatio
 n in Elongating Root Epidermal Cells
URL:https://talks-calendar.ista.ac.at/events/5702
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