Distribution of human PLUNC/BPI fold-containing (BPIF) proteins

Abstract

Although gene expression studies have shown that human PLUNC (palate, lung and nasal epithelium clone) proteins are predominantly expressed in the upper airways, nose and mouth, and proteomic studies have indicated they are secreted into airway and nasal lining fluids and saliva, there is currently little information concerning the localization of human PLUNC proteins. Our studies have focused on the localization of three members of this protein family, namely SPLUNC1 (short PLUNC1), SPLUNC2 and LPLUNC1 (long PLUNC1). Western blotting has indicated that PLUNC proteins are highly glycosylated, whereas immunohistochemical analysis demonstrated distinct patterns of expression. For example, SPLUNC2 is expressed in serous cells of the major salivary glands and in minor mucosal glands, whereas SPLUNC1 is expressed in the mucous cells of these glands. LPLUNC1 is a product of a population of goblet cells in the airway epithelium and nasal passages and expressed in airway submucosal glands and minor glands of the oral and nasal cavities. SPLUNC1 is also found in the epithelium of the upper airways and nasal passages and in airway submucosal glands, but is not co-expressed with LPLUNC1. We suggest that this differential expression may be reflected in the function of individual PLUNC proteins.

Dual Acute Proinflammatory and Antifibrotic Pulmonary Effects of Short Palate, Lung, and Nasal Epithelium Clone–1 after Exposure to Carbon Nanotubes

“…Originally named PLUNC (11), the gene product now called SPLUNC1 (short PLUNC1) is also referred to as secretory protein in upper respiratory tract (12), lung-specific X protein (13), nasopharyngeal carcinoma-related protein (14), or bactericidal/ permeability-increasing-fold containing (BPIF) A1 protein (15). SPLUNC1 encodes a richly secreted protein detected in human sputum and tracheobronchial secretions, as well as in saliva (16), nasal lavage fluid (17), and apical secretions from cultured human tracheobronchial epithelial cells (11,12,18).…”

Increased expression of BPI fold-containing family A member 1 is associated with metastasis and poor prognosis in human colorectal carcinoma

“…Based on their predicted structure of being homologous to one or both domains of the bactericidal or permeability-increasing protein (BPI), PLUNCs can be subdivided in two groups: Short (SPLUNC) and long (LPLUNC) proteins (11). Recently, PLUNC family members have been included in the BPI fold-containing superfamily, leading to a novel nomenclature whereby SPLUNC1 protein has the designation BPIFA1 (25,26). Previously, various antimicrobial activities have been attribu ted to BPIFA1, in addition to evidence that it may function as a host defense protein (4,6,7).…”

Salivary BPIFA1 (SPLUNC1) and BPIFA2 (SPLUNC2 A) are modified by head and neck cancer radiotherapy

“…24 This difference in expression suggests that each one occupies an individual niche and potentially has individual functions. 18 ; 20 Irradiation appears to have a greater effect on the function of parotid glands because serous acini are more susceptible to permanent radiotherapyinduced damage than are mucous acini, 43 resulting in thicker saliva. As a serous salivary gland, the parotid gland only produces one of the BPIF proteins, BPIFA2, and thus we might have expected to see a greater effect of radiation therapy on BPIFA2 levels.…”