SYT14L, especially its C2 domain, is involved in regulating melanocyte differentiation.

Department of Physiology, Institute of Health Sciences and Medical Research Center for Neural Dysfunction, School of Medicine, Gyeongsang National University, Jinju 660-751, Republic of Korea.
Journal of dermatological science (Impact Factor: 3.71). 08/2013; DOI: 10.1016/j.jdermsci.2013.07.010
Source: PubMed

ABSTRACT The formation of dendrites by melanocytes is highly analogous to that process in neural cells. We previously reported that a C2 domain-containing protein, copine-1, is involved in the extension of dendrites by neural cells. However, the effect of C2 domain-containing proteins in dendrite formation by melanocytes has not yet been elucidated.
The aim of this study was to screen novel C2 domain-containing proteins related to dendrite outgrowth in melanocytes and to investigate their precise roles in melanocyte dendrite formation during differentiation.
We transduced mouse melan-a melanocytes with a recombinant adenovirus expressing a C2 domain library. Dendrite elongation, melanin content, tyrosinase activity and Western blot analyses were conducted to elucidate the possible underlying mechanisms of action in melanocytes.
Sixteen sets of C2 domain-containing proteins were identified whose over-expression resulted in dendrite lengthening. Among those, we focused on the C2 domain of SYT14L (truncated mutant of SYT14L) in this study. Forced expression of full length SYT14L or the C2 domain of SYT14L induced a significant elongation of dendrite length accompanied by the induction of melanocyte differentiation-related markers, including melanin synthesis, tyrosinase catalytic activity and the expression of tyrosinase (TYR), tyrosinase related protein-1 (TRP-1) and TRP-2. In addition, over-expression of either the C2 domain or the full length form of SYT14L significantly increased the phosphorylation of ERK and CREB.
These results suggest that SYT14L, especially its C2 domain, may play an important role in regulating melanocyte differentiation through the modulation of ERK and (or) CREB signaling.

  • [Show abstract] [Hide abstract]
    ABSTRACT: REGULATION of pigmentation is of considerable importance throughout the animal kingdom. Photoprotection, social behaviour, and a number of disorders like albinism, vitiligo, and melanoma are affected by the amount and distribution of melanin in the organism. Melanin is synthesised in melanosomes beginning with the oxidation of tyrosine to dihydroxy-phenyalanine (DOPA) by the enzyme tyrosinase. In Cloudman S91 melanoma cells, tyrosinase activity and melanisation are stimulated by elevated intracellular levels of cyclic AMP1, apparently through the inactivation of an inhibitor of tyrosinase2. We initiated a series of experiments to identify the molecules controlling tyrosinase activity. Kuo and Greengard's observations on the widespread occurrence of cyclic AMP-dependent protein kinases throughout the phyla suggested that protein phosphorylation reactions might be involved3. We describe here a cell-free system in which tyrosinase is activated following the addition of a cyclic AMP-dependent protein kinase isolated from melanoma cells. The kinetics of the reaction in the cell-free system are similar to those in intact cells. The activation of tyrosinase is completely dependent on the protein kinase and is enhanced by cyclic AMP, ATP, and magnesium. The activation involves the removal of an inhibitor of tyrosinase; in addition, a phosphoprotein phosphatase is present which is distinct from the inhibitor but which appears to antagonize the kinase-mediated reaction.
    Nature 07/1977; 267(5610):444-7. · 38.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Copine1 is a ubiquitously expressed protein found in various tissues including the brain, but little is known about the physiological function of this protein. Here, we showed that copine1 is involved in neuronal differentiation. Over-expression of copine1 clearly increased neurite outgrowth and expression of Tuj1, a neuronal marker protein, in HiB5 cells. In addition, endogenous copine1 was transiently increased at the early time during neuronal differentiation of HiB5 cells. When the expression of endogenous copine1 was knocked-down by its specific shRNA, PDGF-mediated neurite outgrowth was clearly decreased in HiB5 cells. Furthermore, over-expression of copine1 increased phosphorylation of Akt and copine1-specific shRNA decreased phosphorylation of Akt during neuronal differentiation of HiB5 cells. Interestingly, the phosphorylation level of PI3K, generally known as an upstream protein of Akt, was not changed by copine1 expression. These results suggest that copine1 enhances neuronal differentiation of HiB5 cells not through the PI3K-Akt pathway, but by using another Akt activated signal pathway.
    Molecules and Cells 12/2012; 34(6):549-54. · 2.21 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In mammalian melanocytes, melanin synthesis is controlled by tyrosinase, the critical enzyme in the melanogenic pathway. We and others showed that the stimulation of melanogenesis by cAMP is due to an increased tyrosinase expression at protein and mRNA levels. However, the molecular events connecting the rise of intracellular cAMP and the increase in tyrosinase activity remain to be elucidated. In this study, using B16 melanoma cells, we showed that cAMP-elevating agents stimulated mitogen-activated protein (MAP) kinase, p44mapk. This effect was mediated by the activation of MAP kinase kinase. cAMP-elevating agents induced a translocation of p44mapk to the nucleus and an activation of the transcription factor AP-1. cAMP-induced AP-1 contained FOS-related antigen-2 in association with JunD, while after phorbol ester stimulation AP-1 complexes consist mainly of JunD/c-Fos heterodimers. In an attempt to connect these molecular events to the control of tyrosinase expression that appears to be the pivotal point of melanogenesis regulation, we hypothesized that following its activation by cAMP, p44mapk activates AP-1. Then AP-1 could stimulate tyrosinase expression through the interaction with specific DNA sequences present in the mouse tyrosinase promoter.
    Journal of Biological Chemistry 11/1995; 270(41):24315-20. · 4.65 Impact Factor