Structural Analysis of the Smad2−MAN1 Interaction That Regulates Transforming Growth Factor-β Signaling at the Inner Nuclear Membrane

Biochemistry ◽  
2010 ◽  
Vol 49 (37) ◽  
pp. 8020-8032 ◽  
Author(s):  
Emilie Kondé ◽  
Benjamin Bourgeois ◽  
Carine Tellier-Lebegue ◽  
Wei Wu ◽  
Javier Pérez ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Growth Factor ◽  
Nuclear Membrane ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Inner Nuclear Membrane

scholarly journals The Integral Inner Nuclear Membrane Protein MAN1 Physically Interacts with the R-Smad Proteins to Repress Signaling by the Transforming Growth Factor-β Superfamily of Cytokines

2005 ◽  
Vol 280 (16) ◽  
pp. 15992-16001 ◽  
Author(s):  
Deng Pan ◽  
Luis D. Estévez-Salmerón ◽  
Shannon L. Stroschein ◽  
Xueliang Zhu ◽  
Jun He ◽  
...  
Keyword(s):  
Growth Factor ◽  
Membrane Protein ◽  
Nuclear Membrane ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Activin Signaling ◽  
Inner Nuclear Membrane ◽  
Smad Proteins ◽  
Inner Nuclear Membrane Protein ◽  
Nuclear Membrane Protein

Smad proteins are critical intracellular mediators of the transforming growth factor-β, bone morphogenic proteins (BMPs), and activin signaling. Upon ligand binding, the receptor-associated R-Smads are phosphorylated by the active type I receptor serine/threonine kinases. The phosphorylated R-Smads then form heteromeric complexes with Smad4, translocate into the nucleus, and interact with various transcription factors to regulate the expression of downstream genes. Interaction of Smad proteins with cellular partners in the cytoplasm and nucleus is a critical mechanism by which the activities and expression of the Smad proteins are modulated. Here we report a novel step of regulation of the R-Smad function at the inner nuclear membrane through a physical interaction between the integral inner nuclear membrane protein MAN1 and R-Smads. MAN1, through the RNA recognition motif, associates with R-Smads but not Smad4 at the inner nuclear membrane in a ligand-independent manner. Overexpression of MAN1 results in inhibition of R-Smad phosphorylation, heterodimerization with Smad4 and nuclear translocation, and repression of transcriptional activation of the TGFβ, BMP2, and activin-responsive promoters. This repression of TGFβ, BMP2, and activin signaling is dependent on the MAN1-Smad interaction because a point mutation that disrupts this interaction abolishes the transcriptional repression by MAN1. Thus, MAN1 represents a new class of R-Smad regulators and defines a previously unrecognized regulatory step at the nuclear periphery.

Perianale Fisteln bei CED: vom Mausmodell zur Klinik

2018 ◽  
Vol 75 (5) ◽  
pp. 287-294
Author(s):  
Michael Scharl
Keyword(s):  
Growth Factor ◽  
Morbus Crohn ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Interleukin 13

Zusammenfassung. Fisteln stellen nach wie vor eine der wichtigsten Komplikationen bei Patienten mit Morbus Crohn dar. Bei mindestens einem Drittel aller Morbus Crohn Patienten treten im Laufe der Erkrankung Fisteln auf. Eine dauerhafte Heilung der Fistel wird jedoch, auch unter Ausschöpfung sämtlicher medikamentöser und chirurgischer Therapieoptionen, nur in rund einem Drittel dieser Patienten erreicht. Der genaue molekulare Mechanismus der Fistelentstehung ist bis heute nicht ganz klar. Aus histopathologischer Sichtweise stellen Fisteln eine röhrenartige Struktur dar, welche von flachen epithelartigen Zellen ausgekleidet ist. Als ursächlicher Entstehungsmechanismus wird dabei die sogenannte epitheliale-zu-mesenchymale Transition (EMT) angesehen und es kann eine starke Expression der Entzündungsmediatoren Tumor Nekrose Faktor, Interleukin-13 und Transforming Growth Factor β in den Fistelarealen nachgewiesen werden. Zusätzlich zu den bereits etablierten, medikamentösen Therapieoptionen, also Antibiotika, Immunmodulatoren und anti-TNF Antikörper, stellt insbesondere der Einsatz der mesenchymalen Stammzelltherapie einen erfolgversprechenden Therapieansatz für die Zukunft dar.

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