Zhou, Yuqiao
(2016)
INACTIVATION OF IRE1α IN OSTERIX-CRE EXPRESSING DENTAL MESENCHYME DISRUPTS DENTIN FORMATION.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Endoplasmic reticulum (ER) stress signaling is a cellular adaptive mechanism that is activated in response to the accumulation of misfolded and/or unfolded proteins in the ER lumen, a cellular stress termed ER stress. Inositol requiring enzyme 1α (IRE1α) is an ER membrane-resident proximal sensor for ER stress. Herein, we aim to determine the biological role of IREα in regulating dentinogenesis in vivo, by selectively deleting IRE1α in Osterix-expressing cells, including odontoblasts. Isolated molars from IRE1α conditional knockout (Ire1a CKO) mice displayed a significantly (p < 0.05) reduced mRNA expression of genes involved in the ER biogenesis and clearance of mal-folded/misfolded proteins, e.g., endoplasmic reticulum–localized DnaJ 4 (ERdj4), compared with their control littermates. Consequently, IRE1α deficiency leads to heightened ER stress, as evidenced by increased protein expression of ER stress markers, e.g., phosphorylated PKR-like kinase (p-PERK) and phosphorylated eukaryotic initiation factor 2α (p-eIF2α), in IRE1α-deficient odontoblasts, compared with WT odontoblasts shown by Immunohistochemistry staining. Odontoblast deficiency of IRE1α resulted in significantly decreased dentin matrix deposition rate, and consequently reduced dentin thickness and an increased ratio of predentin vs. dentin thickness, as shown by calcein double labeling and H&E staining respectively (p < 0.05). Micro-computed tomography analysis demonstrated a significantly reduced root dentin volume in the IRE1α-deficient molars, compared with control counterparts. Furthermore, it was found that odontoblast deficiency of IRE1α resulted in compromised odontoblastic differentiation and/or function, as reflected by significantly reduced gene and/or protein expression of odontoblast differentiation markers, e.g., dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP1), and alpha-1 type I collage (COL1), in the odontoblasts of IRE1α-deficient molars, compared with control counterparts. In addition, IRE1α-deficiency in odontoblast leads to a decrease of β-catenin protein expression in the pulp and odontoblast cell layer of Ire1a CKO mice. Collectively, these data demonstrate that IRE1α is a critical physiological regulator for dentinogenesis.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
13 December 2016 |
| Date Type: |
Publication |
| Defense Date: |
28 November 2016 |
| Approval Date: |
13 December 2016 |
| Submission Date: |
7 December 2016 |
| Access Restriction: |
2 year -- Restrict access to University of Pittsburgh for a period of 2 years. |
| Number of Pages: |
40 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
School of Dental Medicine > Dental Science |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Dentinogenesis;Odontoblast;ER stress signaling; IRE1; XBP1 |
| Date Deposited: |
13 Dec 2016 22:08 |
| Last Modified: |
13 Dec 2018 06:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/30505 |
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