Protein's Dual Location Gave Clue to Role in Cellular Motion

Cell biologists gained deeper insights into the molecular mechanism that regulates how cells move by isolating a protein linked to cellular motion that affects both gene expression and protein transport.

Investigators at the University of California, Santa Barbara (USA) isolated the mDpy-30 protein from various mammalian cells where it exists as a subunit of several histone H3 lysine 4-(H3K4)-methyltransferase (H3K4MT) complexes, in the nucleus and at the trans-Golgi network (TGN).

They reported in the August 3, 2009, online edition of the Journal of Cell Biology that altering mDpy-30 levels changed the distribution of cation-independent mannose 6-phosphate receptor (CIMPR) without affecting that of the TGN marker protein TGN46 or of transferrin receptor. The results indicated that mDpy-30 functioned in endosome to TGN transport of CIMPR, and that its knockdown resulted in the enrichment of internalized CIMPR and recycling of endosomes near cell protrusions.

"We have obtained preliminary evidence that mDpy-30 is an important regulator of cell movement,” said senior author Dr. Dzwokai Ma, assistant professor of molecular, cellular, and developmental biology at the University of California, Santa Barbara. "The movement of a cell is essential to myriad biological functions such as neural networking, proper immunological function, and wound healing. Consequently, when these processes go awry, they can result in the development or progression of human disease, including cancer metastasis.”

"We first found that this protein has a dual location in the cell,” said Dr. Ma, "That spurred us to investigate this protein further, because location is always linked to function.”

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