Cloning of Chicken Pre-B-cell Colony-Enhancing Factor 1 (PBEF1) and Characterization of its Spatial Expression

Abstract

The pre-B-cell colony-enhancing factor 1 (PBEF1) was originally identified from lymphocytes in human as a cytokine to enhance the pre-B-cell colony formation. However, most recent studies demonstrated that it could also mimic effects of insulin and lower plasma glucose level in mice. Using chicken as the experiment model to explore its potential physiological roles in lower vertebrates, we cloned the full-length cDNA coding for PBEF1 from chicken ovary. It encodes for a 493 amino acid peptide and shares extremely high homology (~94%) with that of mouse, rat and human. Interestingly, unlike most of the cytokines identified, the putative chicken PBEF1 lacks a typical signal peptide sequence at its N-terminus, thereby raising an interesting issue whether Chicken PBEF1 represents a secreted cytokine or a cytosolic enzyme as reported in rats and mice. Using RT-PCR and Northern blot analysis, we noticed that chicken PBEF1 was abundantly expressed in all of the examined tissues including brain, heart, lung, liver, intestine, kidney, muscle, ovary, pancreas, testis, pituitary and spleen. The ubiquitous expression of chicken PBEF1, together with its conserved amino acid sequence, clearly implies that PBEF1 might play critical role in a variety of tissues besides lymphoid tissue and fatty tissues found in vertebrates.