Event Title

Interaction of the Mid1 Pleckstin Homology Domain with the Major Contractile Ring Element, F-Actin of the Fission Yeast Schizosaccharomyces Pombe

Location

Hager-Lubbers Exhibition Hall

Start Date

16-4-2013 3:30 PM

Description

PURPOSE: Cancer is a disease of uncontrolled cell division. Cell division in eukaryotic cells occurs by the formation of a contractile ring, predominantly composed of filamentous actin (F-actin). During mitosis, actin filaments polymerize to form anti-parallel rings at the medial plane of the cell that constrict causing the cell membrane to pinch and divide. Proteins that regulate this process are essential because dysregulation can lead to uninhibited cell growth and division. In fission yeast, the protein Mid1 functions as a scaffold to recruit regulatory proteins required for actin filament formation and simultaneously anchors the contractile ring at the cell division site. The Mid1 Pleckstrin Homology (PH) domain can bind lipids in the membrane, but direct binding of the PH domain to other contractile ring proteins has not been described. Since F-actin and Mid1 are crucial components for contractile ring formation and proper cytokinesis, it is important to clarify their interaction. SUBJECTS: Purified Mid1 PH domain and F-actin proteins were used for in vitro studies. METHODS: Binding between F-actin and the Mid1 PH domain was confirmed by cosedimentation assay. The significance of the interaction was analyzed by spontaneous actin polymerization assays and rhodamine-phalloidin staining. Results and CONCLUSIONS: The PH domain inhibited F-actin polymers from forming in a dose-dependent manner. This phenomenon was confirmed by rhodamine-phalloidin staining of actin filaments in the presence of the PH domain. The inhibitory effect of the Mid1 PH domain on F-actin may reveal an important regulatory event for actin polymerization during contractile ring assembly.

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Apr 16th, 3:30 PM

Interaction of the Mid1 Pleckstin Homology Domain with the Major Contractile Ring Element, F-Actin of the Fission Yeast Schizosaccharomyces Pombe

Hager-Lubbers Exhibition Hall

PURPOSE: Cancer is a disease of uncontrolled cell division. Cell division in eukaryotic cells occurs by the formation of a contractile ring, predominantly composed of filamentous actin (F-actin). During mitosis, actin filaments polymerize to form anti-parallel rings at the medial plane of the cell that constrict causing the cell membrane to pinch and divide. Proteins that regulate this process are essential because dysregulation can lead to uninhibited cell growth and division. In fission yeast, the protein Mid1 functions as a scaffold to recruit regulatory proteins required for actin filament formation and simultaneously anchors the contractile ring at the cell division site. The Mid1 Pleckstrin Homology (PH) domain can bind lipids in the membrane, but direct binding of the PH domain to other contractile ring proteins has not been described. Since F-actin and Mid1 are crucial components for contractile ring formation and proper cytokinesis, it is important to clarify their interaction. SUBJECTS: Purified Mid1 PH domain and F-actin proteins were used for in vitro studies. METHODS: Binding between F-actin and the Mid1 PH domain was confirmed by cosedimentation assay. The significance of the interaction was analyzed by spontaneous actin polymerization assays and rhodamine-phalloidin staining. Results and CONCLUSIONS: The PH domain inhibited F-actin polymers from forming in a dose-dependent manner. This phenomenon was confirmed by rhodamine-phalloidin staining of actin filaments in the presence of the PH domain. The inhibitory effect of the Mid1 PH domain on F-actin may reveal an important regulatory event for actin polymerization during contractile ring assembly.