Formins are evolutionarily conserved multi-domain proteins participating in the control of both actin and microtubule dynamics. Angiosperm formins form two evolutionarily distinct families, Class I and Class II, with class-specific domain layouts. The model plant Arabidopsis thaliana has 21 formin-encoding loci, including 10 Class II members. In this study, we analyze the subcellular localization of two A. thaliana Class II formins exhibiting typical domain organization, the so far uncharacterized formin AtFH13 (At5g58160) and its distant homolog AtFH14 (At1g31810), previously reported to bind microtubules. Fluorescent protein-tagged full length formins and their individual domains were transiently expressed in Nicotiana benthamiana leaves under the control of a constitutive promoter and their subcellular localization (including co-localization with cytoskeletal structures and the endoplasmic reticulum) was examined using confocal microscopy. While the two formins exhibit distinct and only partially overlapping localization patterns, they both associate with microtubules via the conserved formin homology 2 (FH2) domain and with the periphery of the endoplasmic reticulum, at least in part via the N-terminal PTEN (Phosphatase and Tensin)-like domain. Surprisingly, FH2 domains of AtFH13 and AtFH14 can form heterodimers in the yeast two-hybrid assay-a first case of potentially biologically relevant formin heterodimerization mediated solely by the FH2 domain.
- MeSH
- Arabidopsis genetika metabolismus MeSH
- dimerizace MeSH
- endoplazmatické retikulum metabolismus MeSH
- exprese genu MeSH
- forminy genetika metabolismus MeSH
- mikrotubuly metabolismus MeSH
- proteinové domény MeSH
- proteiny huseníčku genetika metabolismus MeSH
- rekombinantní proteiny genetika metabolismus MeSH
- tabák metabolismus MeSH
- vazba proteinů MeSH
- Publikační typ
- časopisecké články MeSH
Formins are evolutionarily conserved eukaryotic proteins engaged in actin nucleation and other aspects of cytoskeletal organization. Angiosperms have two formin clades with multiple paralogs; typical plant Class I formins are integral membrane proteins that can anchor cytoskeletal structures to membranes. For the main Arabidopsis housekeeping Class I formin, FH1 (At3g25500), plasmalemma localization was documented in heterologous expression and overexpression studies. We previously showed that loss of FH1 function increases cotyledon epidermal pavement cell shape complexity via modification of actin and microtubule organization and dynamics. Here, we employ transgenic Arabidopsis expressing green fluorescent protein-tagged FH1 (FH1-GFP) from its native promoter to investigate in vivo behavior of this formin using advanced microscopy techniques. The fusion protein is functional, since its expression complements the fh1 loss-of-function mutant phenotype. Accidental overexpression of FH1-GFP results in a decrease in trichome branch number, while fh1 mutation has the opposite effect, indicating a general role of this formin in controlling cell shape complexity. Consistent with previous reports, FH1-GFP associates with membranes. However, the protein exhibits surprising actin- and secretory pathway-dependent dynamic localization and relocates between cellular endomembranes and the plasmalemma during cell division and differentiation in root tissues, with transient tonoplast localization at the transition/elongation zones border. FH1-GFP also accumulates in actin-rich regions of cortical cytoplasm and associates with plasmodesmata in both the cotyledon epidermis and root tissues. Together with previous reports from metazoan systems, this suggests that formins might have a shared (ancestral or convergent) role at cell-cell junctions.
Cieľom práce bolo posúdiť stav pacientov s D-transpozíciou veľkých ciev po anatomickej korekcii. Pacienti: autori hodnotili 166 detí (115 chlapcov a 51 dievčat), operovaných od januára 1993 do decembra 2003. Priemerná dĺžka sledovania bola 5,8 roka. Výsledky: včasná mortalita bola 6 % (10 pacientov). U 5 pacientov (4,1 %) bola prítomná supravalvárna stenóza pulmonálnej artérie (PS) s gradientom > 40 mmHg, 4 z nich sa podrobili katetrizačnej a/alebo operačnej dilatácii. 1 pacient (0,8 %) mal operačne korigovanú stenózu ascendentnej aorty (grad. 55 mmHg). Insuficiencia aortálnej chlopne sa vyskytla u 47,5 % pacientov, väčšinou však bola nezávažná. 6 pacientov malo angiografický nález disproporcie alebo chýbania 1 hlavnej vetvy koronárnej artérie, s dostatočným kolaterálnym obehom. Záver: anatomická korekcia je v súčasnosti metódou voľby pre výborné prežívanie a nízky výskyt závažných komplikácií.
The aim of the study was to review the status of patients with D-transposition of the great arteries after arterial switch operation (ASO). Patients: the study included 166 patients (115M/51F), operated on between January 1993 - December 2003. Mean follow-up was 5.8 years. Results: early mortality was 6 % (10 pts). In 5 pts (4.1 %) supravalvar pulmonary stenosis with gradient > 40 mmHg occurred, 4 of them underwent a catheter balloon and/or surgical dilatation. 1 patient (0.8 %) had a surgical treatment of supravalvar aortic stenosis (gradient 55 mmHg). Aortic regurgitation occurred in 47.5 % of patients, mostly trivial or mild. In 6 patients was one thin or completely missing main coronary artery branch found, with sufficient collateral circulation. Conclusion: arterial switch operation (ASO) is at present the method of choice because of low mortality and low incidence of severe complications.
