State-dependent signaling by Ca(v)1.2 regulates hair follicle stem cell function
GENES & DEVELOPMENT
2013; 27 (11): 1217-1222
Using light to control signaling cascades in live neurons
CURRENT OPINION IN NEUROBIOLOGY
2010; 20 (5): 617-622
The signals regulating stem cell activation during tissue regeneration remain poorly understood. We investigated the baldness associated with mutations in the voltage-gated calcium channel (VGCC) Cav1.2 underlying Timothy syndrome (TS). While hair follicle stem cells express Cav1.2, they lack detectable voltage-dependent calcium currents. Cav1.2(TS) acts in a dominant-negative manner to markedly delay anagen, while L-type channel blockers act through Cav1.2 to induce anagen and overcome the TS phenotype. Cav1.2 regulates production of the bulge-derived BMP inhibitor follistatin-like1 (Fstl1), derepressing stem cell quiescence. Our findings show how channels act in nonexcitable tissues to regulate stem cells and may lead to novel therapeutics for tissue regeneration.
View details for DOI 10.1101/gad.216556.113
View details for Web of Science ID 000320110000001
View details for PubMedID 23752588
Prion metal interaction: Is prion pathogenesis a cause or a consequence of metal imbalance?
2009; 181 (3): 282-291
Understanding the complexity of neuronal biology requires the manipulation of cellular processes with high specificity and spatio-temporal precision. The recent development of synthetic photo-activatable proteins designed using the light-oxygen-voltage and phytochrome domains provides a new set of tools for genetically targeted optical control of cell signaling. Their modular design, functional diversity, precisely controlled activity and in vivo applicability offer many advantages for investigating neuronal function. Although designing these proteins is still a considerable challenge, future advances in rational protein design and a deeper understanding of their photoactivation mechanisms will allow the development of the next generation of optogenetic techniques.
View details for DOI 10.1016/j.conb.2010.08.018
View details for Web of Science ID 000283481100015
View details for PubMedID 20850295
Formation of amyloid fibrils by bovine carbonic anhydrase
BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS
2008; 1784 (6): 930-935
Functional role of cellular prion protein (PrPc) has been hypothesized to be in metal homeostasis and providing cells with a superoxide dismutase (SOD)-like activity to escape damage by reactive oxygen species (ROS). PrPc interacts with a range of divalent metal ions and undergoes Cu2+ as well as Zn2+-associated endocytosis, thereby maintaining homeostasis of these and other metal ions. Conformational change to a beta-sheet rich, protease resistant entity, reminiscent of the disease-associated scrapie form called PrPsc, has been found to be induced by interaction of PrPc with metal ions like Cu2+, Zn2+, Mn2+ and Fe2+. This review compiles data from various experimental studies of the interaction of metals with PrPc. The effect of metal ions on the expression and conformation of the prion protein is described in detail with emphasis on their possible physiological and pathogenic role. Further, a hypothesis is presented where attainment of altered conformation by metal-bound PrPc has been viewed as a deleterious consequence of efforts made by cells to maintain metal homeostasis. Thus, PrPc presumably sacrifices itself by converting into PrPsc form in an attempt to protect cells from the toxicity of metal imbalance. Finally, possible reasons for contradictions reported in the literature on the subject are explored and experimental approaches to resolve the same are suggested.
View details for DOI 10.1016/j.cbi.2009.07.021
View details for Web of Science ID 000271043800001
View details for PubMedID 19660443
Amyloids are typically characterized by extensive aggregation of proteins where the participating polypeptides are involved in formation of intermolecular cross beta-sheet structures. Alternate structure attainment and amyloid formation has been hypothesized to be a generic property of a polypeptide, the propensities of which vary widely depending on the polypeptide involved and the physicochemical conditions it encounters. Many proteins that exist in the normal form in-vivo have been shown to form amyloid when incubated in partially denaturing conditions. The protein bovine carbonic anhydrase II (BCA II) when incubated in mildly denaturing conditions showed that the partially unfolded conformers assemble together and form ordered amyloid aggregates. The properties of these aggregates were tested using the traditional Congo-Red (CR) and Thioflavin-T (ThT) assays along with fluorescence microscopy, transmission electron microscopy (TEM), and circular dichroism (CD) spectroscopy. The aggregates were found to possess most of the characteristics ascribed to amyloid fibers. Thus, we report here that the single-domain globular protein, BCA II, is capable of forming amyloid fibrils. The primary sequence of BCA II was also analyzed using recurrence quantification analysis in order to suggest the probable residues responsible for amyloid formation.
View details for DOI 10.1016/j.bbapap.2008.02.020
View details for Web of Science ID 000256655500008
View details for PubMedID 18395531