Limitations of the MRL mouse as a model for cardiac regeneration.

Objective: Myocardial repair following injury in mammals is restricted such that damaged areas are replaced by scar tissue, impairing cardiac function. MRL mice exhibit exceptional regenerative healing in an ear punch wound model. Some myocardial repair with restoration of heart function has also been reported following cryoinjury.

Lys-gamma3-MSH: a global regulator of hormone sensitive lipase activity?

Gamma-melanocyte stimulating hormone (gamma-MSH) is a peptide derived from the ACTH precursor, pro-opiomelanocortin (POMC), and belongs to a family of peptides called the melanocortins that also comprises alpha- and beta-MSH. Although conserved in tetrapods, the biological role of gamma-MSH remains largely undefined. It has been demonstrated previously that gamma-MSH is involved in the regulating the activity of hormone sensitive lipase (HSL) activity in the adrenal and more recently, in the adipocyte.

The patterns of wingless, decapentaplegic, and tinman position the Drosophila heart.

Two secreted signaling molecules, wingless (wg) and decapentaplegic (dpp), are required to specify the heart in Drosophila. wg and dpp are also required to specify other cell types within the mesoderm and in many other regions of the embryo. Because the spatial patterns of wg and dpp are dynamic, different populations of mesodermal cells are exposed to different combinations of wg and/or dpp at different times.

Drosophila's insulin/PI3-kinase pathway coordinates cellular metabolism with nutritional conditions.

Studies in Drosophila have characterized insulin receptor/phosphoinositide 3-kinase (Inr/PI3K) signaling as a potent regulator of cell growth, but its function during development has remained uncertain. Here we show that inhibiting Inr/PI3K signaling phenocopies the cellular and organismal effects of starvation, whereas activating this pathway bypasses the nutritional requirement for cell growth, causing starvation sensitivity at the organismal level. Consistent with these findings, studies using a pleckstrin homology domain-green fluorescent protein (PH-GFP) fusion as an indicator for PI3K activity show that PI3K is regulated by the availability of dietary protein in vivo.