Primary cilia of odontoblasts: possible role in molar morphogenesis.

A primary cilium, a sensory organelle present in almost every vertebrate cell, is regularly described in odontoblasts, projecting from the surfaces of the cells. Based on the hypothesis that the primary cilium is crucial both for dentin formation and possibly in tooth pain transmission, we have investigated the expression and localization of the main cilium components and involvement of the OFD1 gene in tooth morphogenesis. Odontoblasts in vitro express tubulin, inversin, rootletin, OFD1, BBS4, BBS6, ALMS1, KIF3A, PC1, and PC2. In vivo, cilia are aligned parallel to the dentin walls, with the top part oriented toward the pulp core. Close relationships between cilium and nerve fibers are evidenced. Calcium channels are concentrated in the vicinity of the basal body. Analysis of these data suggests a putative role of cilia in sensing the microenvironment, probably related to dentin secretion. This hypothesis is enhanced by the huge defects observed on molars from Ofd1 knockout mice, showing undifferentiated dentin-forming cells.

A natural anatoxin, Amm VIII, induces neutralizing antibodies against the potent scorpion alpha-toxins.

In this study, we have used Amm VIII, a natural anatoxin from the scorpion Androctonus mauretanicus mauretanicus, to elicit specific polyclonal antibodies in rabbit. Using liquid-phase radioimmunoassay, we have studied its selectivity and its neutralizing activity both in vitro and in vivo for the most lethal scorpion alpha-toxins described, in particular the alpha-toxin of reference AaH II. We have shown that the anti-Amm VIII serum prevents the association of 125I-AaH II with its receptor and is able to remove 125I-AaH II already bound to its site (the half-life of the complex 125I-AaH II-receptor site was 12 min in the absence of anti-Amm VIII serum but decreased to only 2 min in the presence of anti-Amm VIII serum). In vivo, the serum also has a protective effect in mice: 42 LD50 of AaH II by millilitre are neutralized, measured by subcutaneous injection.

TRPP2: Ca2+-permeable cation channel and more.

TRPP2 (polycystin-2) is a member of the TRP family of non-selective cation channels that is mutated in human autosomal polycystic kidney disease. It is thought to function together with polycystin-1 (PKD1), a large plasma membrane integral protein, as part of a multiprotein complex involved in transducing Ca2+-dependent mechanosensitive information in renal epithelial cells. TRPP2 has been implicated in Ca2+-dependent pathways in a variety of biological functions and species, including cell proliferation, sperm fertilization, mating behavior and asymmetric gene expression. Although its function as a Ca2+-permeable cation channel is well established, its precise role, regulation and subcellular localization in plasma membrane, endoplasmic reticulum and cilium have remained controversial. The present review summarizes the most pertinent recent evidence regarding the structural and functional properties of TRPP2 channels, focusing on the regulation and physiology of mammalian TRPP2.