Abstract
In mammals, leptin and tumor-necrosis factor (TNF) are prominent interacting adipokines mediating appetite control and insulin sensitivity. While TNF pleiotropically functions in immune defense and cell survival, leptin is largely confined to signaling energy stores in adipocytes. Knowledge about the function of avian leptin and TNF is limited and they are absent or lowly expressed in adipose, respectively. Employing radiation-hybrid mapping and FISH-TSA, we mapped TNF and its syntenic genes to chicken chromosome 16 within the major histocompatibility complex (MHC) region. This mapping position suggests that avian TNF has a role in regulating immune response. To test its possible interaction with leptin within the immune system and beyond, we compared the transcription patterns of TNF, leptin and their cognate receptors obtained by meta-analysis of GenBank RNA-seq data. While expression of leptin and its receptor (LEPR) were detected in the brain and digestive tract, TNF and its receptor mRNAs were primarily found in viral-infected and LPS-treated leukocytes. We confirmed leptin expression in the duodenum by immunohistochemistry staining. Altogether, we suggest that whereas leptin and TNF interact as adipokines in mammals, in birds, they have distinct roles. Thus, the interaction between leptin and TNF may be unique to mammals.
Highlights
In mammals, leptin is a key adipokine that works in concert with other adipokines such as tumor-necrosis factor (TNF) to regulate energy homeostasis [1,2]
We have previously shown that the chicken TNF is expressed primarily in embryonic and adult spleens, as well as in monocytes and macrophages [13,14]
This location was confirmed by using PCR primers for TRIM7.2, BRD2, TAP2 and ABHD16A, which are located within the major histocompatibility complex (MHC) cluster on GGA16 in the current genome assembly (Table 1)
Summary
Leptin is a key adipokine that works in concert with other adipokines such as TNF ( known as TNFα) to regulate energy homeostasis [1,2]. TNF has a broader function in the immune system, which includes immune cell development and functional regulation. This is in addition to TNF’s general role in the control of survival, proliferation, differentiation and death of cells [8]. Leptin and TNF work in concert and stimulate each other’s expression both in the adipose tissue and in immune cells [9,10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
