Medicine and Health Sciences Commons^™

Characterization Of The Key Mouse Cochlear Developmental Genes For Auditory Hair Cell Regeneration, Zhiyong Liu

Theses and Dissertations (ETD)

Mammalian inner ear cochlear auditory hair cells (HCs) and adjacent supporting cells (SCs) are believed to derive from the same progenitors during development. However, unlike SCs of nonmammalian vertebrates, mammalian cochlear SCs cannot be converted into functional hair cells (HCs) after damage, thus leading to permanent deafness. To entitle mammals with the ability to restore hearing capacity after HC damage, we first achieved proliferation of SCs by acute ablation of p27 or Sox2. Secondly, we overactivated Notch1 signaling in the mouse inner ear at different developmental stages, and found that the ability of Notch signaling in generating new HCs declines …

Insights Into P53-Dependent Apoptotic Signaling And Cell Fate Vis-A-Vis Functional Cooperation Among Bcl-Xl, Cytoplasmic P53, And Puma, John C. Fisher

Theses and Dissertations (ETD)

Following DNA damage, nuclear p53 induces the expression of PUMA (p53 upregulated modulator of apoptosis), a BH3‑only protein that binds and inhibits the anti‑apoptotic BCL‑2 repertoire, including BCL‑xL. Structural investigations of PUMA and the BCL‑xL×PUMA BH3 domain complex by X‑ray crystallography and nuclear magnetic resonance (NMR) spectroscopy reveal a novel, PUMA‑induced, domain‑swapped dimerization of BCL‑xL that requires a π‑stacking interaction between PUMA W71 and BCL‑xL H113. PUMA is an intrinsically disordered protein, but upon interaction with BCL‑xL, PUMA W71 and the PUMA BH3 domain residues fold into an alpha helix and subtly remodel BCL‑xL to trigger its dimerization. Wild type …

The Biochemical Pathway Leading To Lpa Generation Upon Blood Coagulation, Alyssa Lynn Jefferson Bolen

Theses and Dissertations (ETD)

Platelet activation initiates an upsurge in 18:2 and 20:4 lysophosphatidic acid (LPA) production. The biochemical pathway responsible for LPA production during blood clotting is not fully understood. We have purified a phospholipase A₁ (PLA₁) from thrombin-activated human platelets using sequential chromatographic steps followed by fluorophosphonate‑biotin affinity labeling and proteomics. We identified acyl‑protein thioesterase 1 (aka. lysophospholipase A1, accession code O75608) as a novel PLA₁. Addition of this recombinant PLA₁ significantly increased the production of sn‑2‑esterified polyunsaturated LPCs and the corresponding LPAs in plasma. We next examined the regioisomeric preference of lysophospholipase …

Novel Insights Into Ubiquitin-Like Protein E1-E2 Interactions, Asad Taherbhoy

Theses and Dissertations (ETD)

Posttranslational modification of macromolecules by ubiquitin-like proteins (UBLs) such as ubiquitin, Sumo and NEDD8 regulate a vast array of processes in the cell. Transfer of UBLs to their target generally occurs by a series of molecular handoffs down an E1‑E2‑E3 cascade. We are interested in understanding how E1‑E2 pairs interact and mediate UBL transfer. To this effect, we studied two E1‑E2 pairs: the Sumo pathway (Sumo utilizes a canonical E1 and E2) and the Atg8 pathway (Atg8 is a UBL involved in autophagy that utilizes a non-canonical E1‑E2 pair).

Sumo conjugation is initiated by the heterodimeric Aos1‑Uba2 E1 enzyme (in …