GPCR-induced calcium transients trigger nuclear actin assembly for chromatin dynamics.

Although the properties of the actin cytoskeleton in the cytoplasm are well characterized, the regulation and function of nuclear actin filaments are only recently emerging. We previously demonstrated serum-induced, transient assembly of filamentous actin within somatic cell nuclei. However, the extracellular cues, cell surface receptors as well as underlying signaling mechanisms have been unclear.

In contrast to Chlamydia trachomatis, Waddlia chondrophila grows in human cells without inhibiting apoptosis, fragmenting the Golgi apparatus, or diverting post-Golgi sphingomyelin transport.

The Chlamydiales are an order of obligate intracellular bacteria sharing a developmental cycle inside a cytosolic vacuole, with very diverse natural hosts, from amoebae to mammals. The clinically most important species is Chlamydia trachomatis. Many uncertainties remain as to how Chlamydia organizes its intracellular development and replication.

Genetic analysis of SCO2997, encoding a TagF homologue, indicates a role for wall teichoic acids in sporulation of Streptomyces coelicolor A3(2).

Streptomyces coelicolor contains two gene clusters putatively involved in wall teichoic acid biosynthesis. Inactivation of the tagF homologue SCO2997 or SCO2584, a component of the Streptomyces spore wall synthesizing complex, affected sporulation. The mutant phenotypes resembled those of mre mutants, suggesting a function of wall teichoic acids in the differentiation of Streptomyces.

The MreB-like protein Mbl of Streptomyces coelicolor A3(2) depends on MreB for proper localization and contributes to spore wall synthesis.

Most bacteria with a rod-shaped morphology contain an actin-like cytoskeleton consisting of MreB polymers, which form helical spirals underneath the cytoplasmic membrane to direct peptidoglycan synthesis for the elongation of the cell wall. In contrast, MreB of Streptomyces coelicolor is not required for vegetative growth but has a role in sporulation. Besides MreB, S.

Proteins encoded by the mre gene cluster in Streptomyces coelicolor A3(2) cooperate in spore wall synthesis.

It is still an open question how an intracellular cytoskeleton directs the synthesis of the peptidoglycan exoskeleton. In contrast to MreB of rod-shaped bacteria, which is essential for lateral cell wall synthesis, MreB of Streptomyces coelicolor has a role in sporulation. To study the function of the S.

Serum components and activated Ha-ras antagonize expression of perivenous marker genes stimulated by beta-catenin signaling in mouse hepatocytes.

Hepatocytes of the periportal and perivenous zones of the liver lobule show marked differences in the contents and activities of many enzymes and other proteins. Previous studies from our and other groups have pointed towards an important role of beta-catenin-dependent signaling in the regulation of expression of genes encoding proteins with preferential perivenous localization, whereas, in contrast, signaling through Ras-dependent pathway(s) may induce a 'periportal' phenotype. We have now conducted a series of experiments to further investigate this hypothesis.