Texas A&M University

About: Texas A&M University is a education organization based out in College Station, Texas, United States. It is known for research contribution in the topics: Population & Gene. The organization has 72169 authors who have published 164372 publications receiving 5764236 citations.

Osteocyte Wnt/β-Catenin Signaling Is Required for Normal Bone Homeostasis

Abstract: β-Catenin-dependent canonical Wnt signaling plays an important role in bone metabolism by controlling differentiation of bone-forming osteoblasts and bone-resorbing osteoclasts. To investigate its function in osteocytes, the cell type constituting the majority of bone cells, we generated osteocyte-specific β-catenin-deficient mice (Ctnnb1loxP/loxP; Dmp1-Cre). Homozygous mutants were born at normal Mendelian frequency with no obvious morphological abnormalities or detectable differences in size or body weight, but bone mass accrual was strongly impaired due to early-onset, progressive bone loss in the appendicular and axial skeleton with mild growth retardation and premature lethality. Cancellous bone mass was almost completely absent, and cortical bone thickness was dramatically reduced. The low-bone-mass phenotype was associated with increased osteoclast number and activity, whereas osteoblast function and osteocyte density were normal. Cortical bone Wnt/β-catenin target gene expression was reduced, and of the known regulators of osteoclast differentiation, osteoprotegerin (OPG) expression was significantly downregulated in osteocyte bone fractions of mutant mice. Moreover, the OPG levels expressed by osteocytes were higher than or comparable to the levels expressed by osteoblasts during skeletal growth and at maturity, suggesting that the reduction in osteocytic OPG and the concomitant increase in osteocytic RANKL/OPG ratio contribute to the increased number of osteoclasts and resorption in osteocyte-specific β-catenin mutants. Together, these results reveal a crucial novel function for osteocyte β-catenin signaling in controlling bone homeostasis.

The Acid-Mediated Denaturation Pathway of Transthyretin Yields a Conformational Intermediate That Can Self-Assemble into Amyloid†

Abstract: Transthyretin (TTR) amyloid fibril formation is observed during partial acid denaturation and while refolding acid-denatured TTR, implying that amyloid fibril formation results from the self-assembly of a conformational intermediate. The acid denaturation pathway of TTR has been studied in detail herein employing a variety of biophysical methods to characterize the intermediate(s) capable of amyloid fibril formation. At physiological concentrations, tetrameric TTR remains associated from pH 7 to pH 5 and is incapable of amyloid fibril formation. Tetrameric TTR dissociates to a monomer in a process that is dependent on both pH and protein concentration below pH 5. The extent of amyloid fibril formation correlates with the concentration of the TTR monomer having an altered, but defined, tertiary structure over the pH range of 5.0−3.9. The inherent Trp fluorescence-monitored denaturation curve of TTR exhibits a plateau over the pH range where amyloid fibril formation is observed (albeit at a higher concentra...

Highly stable porous polymer networks with exceptionally high gas-uptake capacities.

Abstract: Figure 1 . a) Synthetic route for PPN-3 (X: Adamantane), PPN-4 (X: Si), PPN-5 (X: Ge), and PAF-1 (X: C). b) The default noninterpenetrated diamondoid network of PPN-4 (black, C; pale grey, H; grey, Si). For several decades, porous materials have been exploited for their applications in gas storage. [ 1 ] Recently, several metal–organic frameworks (MOFs) with high surface area and gas-uptake capacity have been reported. [ 2 ]

The Global Precipitation Measurement (GPM) Mission for Science and Society

Abstract: The GPM mission collects essential rain and snow data for scientific studies and societal benefit.