CDK2 limits the highly energetic secretory program of mature ß cells by restricting PEP cycle-dependent KATP channel closure.

Hallmarks of mature ß cells are restricted proliferation and a highly energetic secretory state. Paradoxically, cyclin-dependent kinase 2 (CDK2) is synthesized throughout adulthood, its cytosolic localization raising the likelihood of cell cycle-independent functions. In the absence of any changes in ß cell mass, maturity, or proliferation, genetic deletion of Cdk2 in adult ß cells enhanced insulin secretion from isolated islets and improved glucose tolerance in vivo. At the single ß cell level, CDK2 restricts insulin secretion by increasing KATP conductance, raising the set point for membrane depolarization in response to activation of the phosphoenolpyruvate (PEP) cycle with mitochondrial fuels. In parallel with reduced ß cell recruitment, CDK2 restricts oxidative glucose metabolism while promoting glucose-dependent amplification of insulin secretion. This study provides evidence of essential, non-canonical functions of CDK2 in the secretory pathways of quiescent ß cells.

From fragment to clinical candidate--a historical perspective.

As recently as ten years ago few scientists had heard of fragment screening, let alone considered low molecular weight fragments (MW <300) with weak binding affinities to be attractive start points for drug discovery programmes. Today, however, there is widespread acceptance that these fragments can be progressed into lead series and on to become clinical candidates. Consequently, over the past three to four years, fragment-based drug discovery has become firmly established within the biotechnology and pharmaceutical industries as a complimentary strategy to high-throughput screening. In this review, we give a historical perspective of how rapidly fragment-based drug discovery has developed and describe a number of clinical compounds discovered using this approach.