Analyses of Bone Regeneration Capacity of Freeze-Dried Bovine Bone and Combined Deproteinized-Demineralized Bovine Bone Particles in Mandibular Defects: The Potential Application of Biological Forms of Bovine-Bone Filler.

OBJECTIVE: This study aimed to evaluate bone regeneration capacity of FDBX granules compared to composite DBBM/DFDBX granules for filling of bone defect in rabbit mandible. MATERIAL AND METHODS: Critical size defects were created in 45 rabbits' mandible. The defect in the control group is left untreated, while in other groups the defects were filled with FDBX granules and composite DBBM/DFDBX granules, respectively. Specimens were collected at 2, 4, and 8 weeks for histology and immunohistochemical analyses. Significant difference is set at p-value < 0.05. RESULTS: The osteoblast-osteoclast quantification, osteoblast expression of Runx2, alkaline phosphatase, collagen-I, and osteocalcin, and osteoclast expression of receptor activator of NF-kB ligand (RANKL) and osteoprotegerin (OPG) in FDBX groups were statistically comparable (p > 0.05) with the composite group, while OPG/RANKL ratio, bone healing scores, and trabecular area were significantly higher (p < 0.05) in the composite compared to FDBX group. CONCLUSION: Composite DBBM/DFDBX granules, within the limitation of this study, has better bone forming capacity than FDBX granules for filling of bone defects in the mandible.

Dysferlin-deficient myotubes show tethering of different membrane compartments characterized by TMEM16E and DHPRα.

TMEM16E deficiency has been shown to be responsible for human limb-girdle muscular dystrophy LGMD2L. We found that endogenous TMEM16E co-localized with caveolin-3 at cytoplasmic vesicular compartments in a myotube from C2C12 cells (C2C12 myotube) without forming a molecular complex. In contrast, a myotube from murine myoblastic dysferlin-deficient GREG cells (GREG myotube) showed not only co-localization but also constitutive association of caveolin-3 and TMEM16E. GREG myotubes also displayed constitutive association of TMEM16E with DHPRα, which reside in different membrane compartments, indicating increased contact of the different vesicular membrane compartments. Τhese results suggest that a dynamic tethering of different membrane compartments might represent a distorted membrane damage repairing process in the absence of dysferlin.

TMEM16E (GDD1) exhibits protein instability and distinct characteristics in chloride channel/pore forming ability.

TMEM16E/GDD1 has been shown to be responsible for the bone-related late-onset disease gnathodiaphyseal dysplasia (GDD), with the dominant allele (TMEM16E(gdd) ) encoding a missense mutation at Cys356. Additionally, several recessive loss-of-function alleles of TMEM16E also cause late-onset limb girdle muscular dystrophy. In this study, we found that TMEM16E was rapidly degraded via the proteasome pathway, which was rescued by inhibition of the PI3K pathway and by the chemical chaperone, sodium butyrate. Moreover, TMEM16E(gdd) exhibited lower stability than TMEM16E, but showed similar propensity to be rescued. TMEM16E did not exhibit cell surface calcium-dependent chloride channel (CaCC) activity, which was originally identified in TMEM16A and TMEM16B, due to their intracellular vesicle distribution. A putative pore-forming domain of TMEM16E, which shared 39.8% similarity in 98 amino acids with TMEM16A, disrupted CaCC activity of TMEM16A via domain swapping. However, the Thr611Cys mutation in the swapped domain, which mimicked conserved cysteine residues between TMEM16A and TMEM16B, reconstituted CaCC activity. In addition, the GDD-causing cysteine mutation made in TMEM16A drastically altered CaCC activity. Based on these findings, TMEM16E possesses distinct function other than CaCC and another protein-stabilizing machinery toward the TMEM16E and TMEM16E(gdd) proteins should be considered for the on-set regulation of their phenotypes in tissues.

PGE2 targets squamous cell carcinoma cell with the activated epidermal growth factor receptor family for survival against 5-fluorouracil through NR4A2 induction.

We found a linear correlation between the Prostaglandin E(2) (PGE(2)) amount and the NR4A2 expression in oral squamous cell carcinoma (SCC) tissues through a statistical analysis among 41 clinical cases. In SCC cell lines, PGE(2) receptor (EP) ligation by exogenous PGE(2) promoted the NR4A2 expression in the cAMP/protein kinase A (PKA)-dependent manner. The process required a nature of SCC cell represented by constitutive activated epidermal growth factor receptor (EGFR) family. Targeted inactivation of the EGFRs interfered the PGE(2)-dependent NR4A2 expression. The PGE(2)-dependent NR4A2 induction is essential for the resistance to anti-cancer drug-induced apoptosis especially in SCC cells which showed constitutive EGFRs activity via autocrine epiregulin, a ligand for EGFRs. Conversely, SCC cells which lack epiregulin expression in their nature could gain the ability to promote the NR4A2 expression in response to PGE(2) and attain the resistance to anti-cancer drug-induced apoptosis under the existence of exogenous epiregulin. These findings suggest that susceptibility of SCC to anti-cancer drug could be compromised when PGE(2) was delivered in the microenvironment of SCC cells supported by constitutive EGFR family activities as their nature.