Editorial: Colour and form

Cover of the year

When I took over as Editor of Pigment Cell Research one of the new initiatives introduced were the new colour covers that have been widely appreciated. As a continuing part of that initiative, we asked both the editorial board members and the general readership to give their opinion as to the best cover of 2005. Those votes are now in, and both groups have given a clear majority (above 50% of all votes cast) to the February issue, the striking chameleon image provided by Randy Morrison that represented the changing face of the journal as well as the diversity of interests within the field. This image is now awarded the ‘Cover of the year Prize for 2005’.

During the past year, we have also been busy upgrading the journal web site at http://www.pigment.org. One new feature was the virtual issues that allow all papers published in the journal in a particular subject area to be seen in one location rather than having to go over the contents pages of each individual issue. Given the interests of some of our readers, we have now introduced a new ‘Development’ virtual issue, that like the other virtual journals will be expanded as time goes on.

I will also take this opportunity to draw attention to the ‘pigment cell resources’ page on the journal web site that now details the citation and download rate of papers published over the past few years. In this respect, special congratulations go to Dot Bennett and Lynn Lamoreux for their review on the ‘Color loci of mice’ that already leads the citation chart.

Finally, on issues concerning the journal, the publisher will shortly be introducing a new initiative that will gather feedback from authors on their review and production experience. The data generated will help inform editorial and production decision-making with the prime aim of identifying and resolving peer-review or production problems in an effort to increase quality, ensure timely publication, and maximize the journal's development.

Tyrosinase maturation

The genetic information encoded by genes must be translated into proteins if the potential of the cell is to be realized. While many of us with a molecular biological viewpoint tend to think of proteins as linear molecules in which specific domains are illustrated as coloured boxes, the reality is far different. Ever since the first protein structure was determined, understanding how a linear array of amino acids is folded into a fully functional 3-dimensional entity that is far more than the sum of its parts has been a major goal. In this respect Tyrosinase, a copper-containing enzyme with a critical role in melanin synthesis has become an excellent model system for studying protein maturation. In the review by Ning Wang and Dan Hebert, the lessons obtained from the study of Tyrosinase maturation from the synthesis of the protein to its arrival in the melanosome are highlighted, and include both the revelation of melanocyte-specific factors required for correct processing as well as those activities that are more generally implicated in protein folding.

Hermansky–Pudlak

While Tyrosinase represents a model system for studying protein maturation, the melanosome represents a wonderful model for understanding organelle transport. The fact that pigment cells are primarily responsible for the colour of an organism has led to the identification of many diseases with associated defects in pigmentation. The result is large resource of disease-related phenotypes with an increasing number of defined genetic lesions. One such disease that has attracted a considerable amount of interest is Hermansky–Pudlak syndrome (HPS), covered in this issue by a comprehensive review by Maria Wei. Rather than being a single disease, HPS covers a range of disorders that result from defects in intracellular protein trafficking and malfunction of proteins encoded by HPS-associated genes lead to problems in several secretory cell types. As a result, a combination of cell and molecular biology, biochemistry as well as clinical studies has led to a better understanding of the regulation and function of the genes implicated in HPS and to the identification of multi–protein complexes critical for secretory cell function.

Glutamate receptors and Mitf

The expression of genes implicated in melanosome function and biogenesis as well as melanocyte survival is coordinated by the Microphthalmia-associated transcription factor. Understanding what factors and signal transduction pathways might regulate Mitf expression and activity has as a result become a focus for much attention. Recently, the role of Glutamate receptors in melanocyte proliferation has come to prominence owing to the observation that the mGluR1 receptor is implicated in the genesis of melanoma in a mouse model. How glutamate receptors signal in melanocytes and what their downstream targets might be is therefore of considerable interest. In the paper from Hoogduijn et al., a new role for glutamate receptors is revealed – regulation of Mitf expression. This observation may be of crucial importance to our understanding of melanoma as Mitf has recently been implicated in regulating melanocyte and melanoma cell proliferation. Precisely, how the glutamate receptors control Mitf expression and how they might function during normal melanocyte development or in inducing activation or quiescence of melanocyte stem cells are clearly key questions that will need to be addressed.