Synaptogenesis

Agrin-induced phosphorylation of the acetylcholine receptor regulatescytoskeletal anchoring and clustering. Borges, L. S. &Ferns, M. J. Cell Biol. 153 , 1–11 (2001) [Pubmed]

Neuromuscular-junction (NMJ) development requires agrin and the muscle-specificreceptor tyrosine kinase MuSK. Does agrin-induced tyrosine phosphorylationof acetylcholine receptors (AChRs) participate in their localization at theNMJ? The authors addressed this question by expressing 'tyrosine-minus' formsof the AChR β-subunit in cultured myotubes. They found that tyrosinephosphorylation is required for AChR anchoring to the cytoskeleton and contributesto receptor clustering.

Psychiatric disorders

Association between an agouti-related protein gene polymorphism andanorexia nervosa. Vink, T. et al. Mol. Psychiatry 6 , 325–328 (2001)

Agouti-related peptide (AGRP) stimulates food intake and participates inthe regulation of body weight. Vink et al. searched for AGRPpolymorphisms in people with anorexia nervosa and identified two alleles thatwere significantly enriched in the patients. The authors suggest that variationsin AGRP are a risk factor for the development of this eating disorder.

Sensory systems

Effects of membrane potential and tension on prestin, the outer haircell lateral membrane motor protein. Santos-Sacchi, J.et al. J. Physiol. 531 , 661–666 (2001) [Pubmed]

Reciprocal electromechanical properties of rat prestin: the motor moleculefrom rat outer hair cells. Ludwig, J. et al. Proc. NatlAcad. Sci. USA 98 , 4178–4183 (2001) [Pubmed]

Heterologous expression of prestin confers cells with fast motility, indicatingthat this molecule might be the motor protein of outer hair cells (OHCs).These two papers provide additional support for this idea by showing thatmembrane potential and tension have similar effects on prestin in transfectedcells as they do in OHCs. However, the two papers disagree on whether prestinalone has all the characteristics of the OHC motor protein or if additionalproteins are required for the formation of a functional complex.

Development

The winged-helix transcription factor FoxD3 is important for establishingthe neural crest lineage and repressing melanogenesis in avian embryos. Kos, R. et al. Development 128 , 1467–1479 (2001)[Pubmed]

Kos et al. cloned the chick homologue of the transcription factorFoxD3 and found that it might serve two functions during neural-crest development.First, FoxD3 might participate in segregation of neural crest cells, as itsmisexpression led to the appearance of a larger neuroepithelial territoryexpressing neural-crest markers. Second, FoxD3 might repress melanogenesis,as knocking down its expression led to an expansion of the melanoblast lineage.