title: Gene silencing and overexpression of porcine peptidoglycan recognition protein long isoforms: involvement in beta-defensin-1 expression.
abstract: Peptidoglycan recognition proteins (PGRPs) are a group of newly identified proteins with emerging functions in mammalian innate immunity. Here we report the identification and characterization of two long isoforms of porcine PGRP. Their complete cDNA sequences encode predicted peptides of 252 and 598 residues and are named pPGRP-L1 and pPGRP-L2, respectively. These porcine isoforms share identical PGRP domains at their C terminus, which are highly conserved with human and mouse orthologs. pPGRP-L1 is expressed constitutively in several tissues, including bone marrow, intestine, liver, spleen, kidney, and skin. pPGRP-L2 is highly expressed in the duodenum and liver, and expression in intestinal tissues is increased by Salmonella infection. In intestinal cells, expression of both pPGRP-L1 and pPGRP-L2 is increased by bacterial infection. Recombinant pPGRP-L1 and pPGRP-L2 have N-acetylmuramoyl-L-alanine amidase activity. Loss-of-function and gain-of-function experiments indicate that these two pPGRPs are involved in expression of the antimicrobial peptide beta-defensin-1. Silencing of pPGRP-L2 in intestinal cells challenged with Listeria monocytogenes results in downregulation of beta-defensin-1. Conversely, overexpression of pPGRP-L1 or pPGRP-L2 dramatically upregulates expression of beta-defensin-1. Collectively, these findings suggest that porcine PGRPs are involved in antimicrobial peptide expression.
authors.affiliation: Department of Anatomy and Physiology, College of Veterinary Medicine, 228 Coles Hall, Kansas State University, Manhattan, KS 66506-5802, USA.
authors.forename: Yongming
authors.initials: Y
authors.lastname: Sang
authors.forename: Balaji
authors.initials: B
authors.lastname: Ramanathan
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Ross
authors.forename: Frank
authors.initials: F
authors.lastname: Blecha
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D002478:Cells, Cultured; D020868:Gene Silencing; D007422:Intestines / Q000166:cytology; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013552:Swine; D023083:beta-Defensins / Q000096:biosynthesis* / Q000235:genetics*
chemical_list: D002352:Carrier Proteins; C406407:DEFB1 protein, human; D020033:Protein Isoforms; D023083:beta-Defensins; C118897:peptidoglycan recognition protein