Using the fruit fly Drosophila melanogaster as a model organism, this dissertation dissects molecular and biological functions of three proteins: Rootletin (Root), testis-specific
Centrosomin (CnnT) and Spermitin (Sprn). Centrosomes are the major microtubule-organizing centers (MTOCs) in animal cells and each one consists of a pair of centrioles, a mother and a
daughter centriole, surrounded by the pericentriolar material (PCM). Centrosomes play critical roles in cell division, cell polarization and intracellular trafficking, etc. In some cell
types, the mother centriole matures to organize the primary cilium that is important for cell signaling and sensory perception. Cilia are linked at their base to the cell body by a
cytoskeletal structure called the rootlet, whose detailed functions remain largely unknown. We have identified a protein called Rootletin (Root) that localizes at the rootlet in ciliated
neurons. Root is essential for normal neuron-specific behaviors of the flies, including locomotion, mechanosensation, chemosensation and hearing. Furthermore, ultrastructure studies revealed
that Root is required for organizing the rootlet, and we found that rootlet assembly is centriole-dependent. Altogether, we will define the important role of Root in rootlet organization and
its requirement for ciliary functions. Mitochondria are energy centers in cells. In Drosophila, they also participate in sperm tail elongation by providing a structural platform for
microtubule (MT) organization to support the elongating tail. Centrosomin (Cnn) has several variants, its centrosomal forms (CnnC) are essential for functional centrosomes. We discovered that
the other non-centrosomal class of Cnn splice products (CnnT) is mainly expressed in fly testes. And unlike CnnC, which localizes at centrosomes, CnnT localizes to spermatid mitochondria
(nebenkern). Cell culture and in vivo studies show that CnnT is necessary and sufficient to recruit MT-nucleating factors to nucleate MTs on mitochondria. Our study also suggested CnnT is
required for normal sperm elongation and male fertility. Overall, we propose that CnnT promotes assembly of unique MTOCs on the surface of mitochondria where, in elongating sperm cells, it
facilitates sperm tail growth. In the last chapter, we present our study on a novel testis-specific mitochondrial protein named Spermitin (Sprn). Using fluorescence microscopy, we found that
Sprn is a mitochondrial protein localizing in the matrix of the spermatid nebenkern. However, Sprn is dispensable for normal sperm development and male fertility. / A Dissertation submitted to the Department of Biomedical Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2014. / October 30, 2014. / centrosome, cilia, mitochondrion, MTOC, rootlet, spermatogenesis / Includes bibliographical references. / Timothy L. Megraw, Professor Directing Dissertation; Branko Stefanovic, Committee Member; Yanchang Wang, Committee Member; Yi Zhou, Committee
Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_253397 |
| Contributors | Chen, Jieyan (authoraut), Megraw, Timothy L. (professor directing dissertation), Deng, Wu-Min (university representative), Stefanovic, Branko (committee member), Wang, Yanchang (committee member), Zhou, Yi (committee member), Florida State University (degree granting institution), College of Medicine (degree granting college), College of Medicine (degree granting department) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource (103 pages), computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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