6 research outputs found
Properties of Ridges in Elastic Membranes
When a thin elastic sheet is confined to a region much smaller than its size
the morphology of the resulting crumpled membrane is a network of straight
ridges or folds that meet at sharp vertices. A virial theorem predicts the
ratio of the total bending and stretching energies of a ridge. Small strains
and curvatures persist far away from the ridge. We discuss several kinds of
perturbations that distinguish a ridge in a crumpled sheet from an isolated
ridge studied earlier (A. E. Lobkovsky, Phys. Rev. E. 53 3750 (1996)). Linear
response as well as buckling properties are investigated. We find that quite
generally, the energy of a ridge can change by no more than a finite fraction
before it buckles.Comment: 13 pages, RevTeX, acknowledgement adde
Androgen-regulated Formation and Degradation of Gap Junctions in Androgen-responsive Human Prostate Cancer Cells
The constituent proteins of gap junctions, called connexins (Cxs), have a short half-life. Despite this, the physiological stimuli that control the assembly of Cxs into gap junctions and their degradation have remained poorly understood. We show here that in androgen-responsive human prostate cancer cells, androgens control the expression level of Cx32—and hence the extent of gap junction formation—post-translationally. In the absence of androgens, a major fraction of Cx32 is degraded presumably by endoplasmic reticulum–associated degradation, whereas in their presence, this fraction is rescued from degradation. We also show that Cx32 and Cx43 degrade by a similar mechanism. Thus, androgens regulate the formation and degradation of gap junctions by rerouting the pool of Cxs, which normally would have been degraded from the early secretory compartment, to the cell surface, and enhancing assembly into gap junctions. Androgens had no significant effect on the formation and degradation of adherens and tight junction–associated proteins. The findings that in a cell culture model that mimics the progression of human prostate cancer, degradation of Cxs, as well as formation of gap junctions, are androgen-dependent strongly implicate an important role of junctional communication in the prostate morphogenesis and oncogenesis