Date of Award

8-2018

Degree Type

Thesis

Degree Name

Cell and Molecular Biology (M.S.)

Department

Cell and Molecular Biology

First Advisor

Dawn Hart

Second Advisor

Matthew Christians

Third Advisor

Agnieszka Szarecka

Academic Year

2017/2018

Abstract

In animal and yeast cells, cell division (cytokinesis) is facilitated by the formation of a contractile acto-myosin ring (CAR). Proper CAR formation and constriction is heavily reliant on the temporal regulation, phosphorylation, and localization of key proteins. In the fission yeast S. pombe, Mid1 is an important dimeric CAR scaffolding protein that connects the contractile apparatus to the plasma membrane at the right place and time during cytokinesis. Mid1 is confined to both the nucleus and protein assemblies called nodes during interphase, and transitions to the cell cortex at mitotic entry as nodes mature and coalesce into the CAR. Rad24 is a 14-3-3 protein involved in cell cycle checkpoints known to interact with CAR proteins and some of their regulators. 14-3-3 proteins bind to a conserved consensus phosphorylation motif, RXXpS, which is targeted by Sid2 and other NDR-kinases. The Septation Initiation Network (SIN) is a conserved signaling pathway to facilitate separation of two new daughter cells. Sid2, the terminal kinase of the SIN, has numerous targets in the CAR, including Mid1. Removal of Rad24 has distinct consequences on the timing of major cytokinetic events.

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