Evolution of the phospho-tyrosine signaling machinery in premetazoan lineages

Tyrosine phosphorylation: thirty years and counting

In the 30 years since its discovery, tyrosine phosphorylation has emerged as a fundamentally important mechanism of signal transduction and regulation in all eukaryotic cells, governing many processes, including cell proliferation, cell cycle progression, metabolic homeostasis, transcriptional activation, neural transmission, differentiation and development, and aging. Perturbations in tyrosine phosphorylation underlie many human diseases, and in particular cancer, and this has prompted the development of inhibitors of tyrosine kinases implicated in disease, a number of which have been approved for clinical use. The following is a brief personal reflection on some of the salient findings over the past 30 years that led to the development of tyrosine kinase inhibitors for disease therapy.

Evolution of protein phosphatases in plants and animals

Protein phosphorylation appears to be a universal mechanism of protein regulation. Genomics has provided the means to compile inventories of protein phosphatases across a wide selection of organisms and this has supplied insights into the evolution of this group of enzymes. Protein phosphatases evolved independently several times yielding the groups we observe today. Starting from a core catalytic domain, phosphatases evolved by a series of gene duplication events and by adopting the use of regulatory subunits and/or fusion with novel functional modules or domains. Recent analyses also suggest that the serine/threonine specific enzymes are more ancient than the PTPs (protein tyrosine phosphatases). It is likely that the latter played a key role at the onset of metazoan evolution in conjunction with the tremendous expansion of tyrosine kinases and PTPs at this point. In the present review, we discuss the evolution of the PTPs, the serine/threonine specific PPP (phosphoprotein phosphatase) and PPM (metallo-dependent protein phosphatase) families and the more recently discovered phosphatases that utilize an aspartate-based catalytic mechanism. We will also highlight examples of convergent evolution and several phosphatases which are unique to plants.

2008: Signaling breakthroughs of the year

This year's signaling breakthroughs extended from protein crystals to cells and subcellular structures to whole genomes. Nominations included research on synapses in brains and in B cells; the evolution and regulation of signaling networks; the identification of a new class of plant hormones; insights into the causes and treatments of disease, such as cancer and schizophrenia; and a possible way to stay in shape while avoiding exercise.

The molecular origins of multicellular transitions

Multicellularity has evolved multiple times independently from a variety of ancestral unicellular lineages. Past research on multicellularity was focused more on explaining why it was repeatedly invented and less so on the molecular foundations associated with each transition. Several recent comparative functional analyses of microbial unicellular and multicellular genomes have begun to throw considerable light on the molecular commonalities exhibited by independent multicellular transitions. These have enabled the delineation of the likely functional components of the genetic toolkit required for multicellular existence and to surprising discoveries, such as the presence of several toolkit components in unicellular lineages. The study of these toolkit proteins in a unicellular context has begun yielding insights into their ancestral functions and how they were coopted for multicellular development.