CUR - The Council on Undergraduate Research

Fission Yeast Polycystin Pkd2p Promotes Cell Growth Synergistically with the MOR Pathway

Denisa Ivan, Debatrayee Sinha, Dr. Qian Chen, Department of Biological Sciences, University of Toledo, 2801 Bancroft St, Toledo, OH 43606.

Mutations of human Polycystins lead to a common genetic disorder, Autosomal Dominant Polycystic Kidney Disorder marked by growth of numerous kidney cysts. However, the cellular role of Polycystins in regulating cystic growth remains poorly understood. In our lab we recently discovered that the fission yeast Polycystins homologue Pkd2p, is a novel regulator of cell growth. The temperature sensitive mutant of pkd2—pkd2-B42 showed severely reduced growth rate at restrictive temperature. Morphological studies revealed that pkd2 mutant cells failed tip growth and volume expansion. To understand Pkd2p’s role in cell growth, we examined whether it has any relationship with the MOR signaling pathway. MOR or morphogenesis orb6 related network is a conserved Hippo like kinase pathway essential for polarized cell growth in fission yeast. The double mutant of pkd2-B42 and the MOR mutants showed reduced viability compared to either of the single mutant, revealing a negative genetic interaction. This implies that MOR and Pkd2p might be acting in the same or complimentary pathways to control cell growth. MOR mutants lack cell growth through tip expansion, but can continue depolarized lateral growth, therefore they attain spherical shape. Morphological analysis of the double mutant cells showed that even the lateral growth was prevented. Further a high percentage of the cells appeared darkened as if shrunk. In conclusion we can say, that Pkd2p helps in cell expansion and synergistically act with the MOR pathway in promoting cell growth.

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