Do Class I Myosins Exert Their Functions through Regulation of Actin Dynamics?

Arabidopsis formin 2 regulates cell-to-cell trafficking by capping and stabilizing actin filaments at plasmodesmata

eLife ◽

10.7554/elife.36316 ◽

2018 ◽

Vol 7 ◽

Cited By ~ 17

Author(s):

Min Diao ◽

Sulin Ren ◽

Qiannan Wang ◽

Lichao Qian ◽

Jiangfeng Shen ◽

...

Keyword(s):

Actin Filaments ◽

Transmembrane Domain ◽

Class I ◽

Actin Dynamics ◽

Developmental Defect ◽

Cell Trafficking ◽

Loss Of Function ◽

Localization Signal

Here, we demonstrate that Arabidopsis thaliana Formin 2 (AtFH2) localizes to plasmodesmata (PD) through its transmembrane domain and is required for normal intercellular trafficking. Although loss-of-function atfh2 mutants have no overt developmental defect, PD’s permeability and sensitivity to virus infection are increased in atfh2 plants. Interestingly, AtFH2 functions in a partially redundant manner with its closest homolog AtFH1, which also contains a PD localization signal. Strikingly, targeting of Class I formins to PD was also confirmed in rice, suggesting that the involvement of Class I formins in regulating actin dynamics at PD may be evolutionarily conserved in plants. In vitro biochemical analysis showed that AtFH2 fails to nucleate actin assembly but caps and stabilizes actin filaments. We also demonstrate that the interaction between AtFH2 and actin filaments is crucial for its function in vivo. These data allow us to propose that AtFH2 regulates PD's permeability by anchoring actin filaments to PD.

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Electron microscopy analysis of degenerating pancreatic ß cells in transgenic mice expressing the MHC Class I antigen Dd

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100160297 ◽

1990 ◽

Vol 48 (3) ◽

pp. 548-549

Author(s):

T. A. Stewart ◽

D. Liggitt ◽

S. Pitts ◽

L. Martin ◽

M. Siegel ◽

...

Keyword(s):

Type I Diabetes ◽

Disease Process ◽

Class Ii ◽

Class I ◽

Type I ◽

Aberrant Expression ◽

Mhc Molecules ◽

Endogenous Insulin ◽

Class Ii Mhc ◽

Ifn Γ

Insulin-dependant (Type I) diabetes mellitus (IDDM) is a metabolic disorder resulting from the lack of endogenous insulin secretion. The disease is thought to result from the autoimmune mediated destruction of the insulin producing ß cells within the islets of Langerhans. The disease process is probably triggered by environmental agents, e.g. virus or chemical toxins on a background of genetic susceptibility associated with particular alleles within the major histocompatiblity complex (MHC). The relation between IDDM and the MHC locus has been reinforced by the demonstration of both class I and class II MHC proteins on the surface of ß cells from newly diagnosed patients as well as mounting evidence that IDDM has an autoimmune pathogenesis. In 1984, a series of observations were used to advance a hypothesis, in which it was suggested that aberrant expression of class II MHC molecules, perhaps induced by gamma-interferon (IFN γ) could present self antigens and initiate an autoimmune disease. We have tested some aspects of this model and demonstrated that expression of IFN γ by pancreatic ß cells can initiate an inflammatory destruction of both the islets and pancreas and does lead to IDDM.

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