Expression and functions of proteases in vascular tissues.
With the emergence of new models for wood formation and the increasing emphasis on improving the efficiency of cellulosic biofuel production, research on vascular tissue biology has intensified in recent years. Some of the most active areas of research focus on manipulating activity of enzymes in the cellulose, hemicellulose, pectin and lignin pathways. In addition, great strides have been made in the characterization of transcriptional networks controlling genes that affect differentiation, secondary cell wall synthesis and programmed cell death in xylem. Less attention has been devoted to the characterization of proteases that may be important regulators of post-translational events that affect vascular cell differentiation and function and cell wall composition. Several genes for proteases and components of the ubiquitin/26S proteasome pathway are upregulated in xylem and phloem and in cell culture systems for studying the differentiation of xylem tracheary elements (TEs). Although small molecule protease inhibitors have been used to explore the roles of proteases during the differentiation of cultured TEs, only a small number of vascular tissue-associated protease genes have been directly tested to determine whether they play roles in vascular tissue biology. In this report, we review roles for proteases in vascular cell differentiation and function as determined through the use of protease inhibitors and genetic analyses and conclude by identifying opportunities for future research in this area.
Department of Horticulture, Virginia Tech, Blacksburg, VA 24061, USA.
H Earl
HE
Petzold
Mingzhe
M
Zhao
Eric P
EP
Beers
D002454:Cell Differentiation; D002473:Cell Wall / Q000201:enzymology*; D004789:Enzyme Activation; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008024:Ligands; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D063245:Plant Development; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D010944:Plants / Q000201:enzymology* / Q000235:genetics; D011480:Protease Inhibitors / Q000737:chemistry; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D011499:Protein Processing, Post-Translational; D052584:Xylem / Q000235:genetics / Q000378:metabolism
D008024:Ligands; D010940:Plant Proteins; D011480:Protease Inhibitors; D061988:Proteasome Inhibitors; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease