Construction Of GOLPH2 Knockout Mouse And Preliminary Study Of GOLPH2’s Function In The Immune System

Golgi phosphoprotein 2(GOLPH2) is a Golgi-residing protein mainly expressed in epithelial tissues. In normal conditions, GOLPH2 is anchored on the Golgi membrane, and is speculated to be involved in post-translational modification of other proteins. However, GOLPH2 can be secreted outside cells under certain not well defined pathological conditions. Some studies found that GOLPH2 were up-regulated significantly in viral hepatitis, cirrhosis and in patients of hepatocellular carcinoma(HCC), both in the serum and in tissues. Thus, GOLPH2 levels could be a serum marker for early detection of HCC with potentially greater sensitivity and specificity than α-fetoprotein(AFP), a traditional biomarker for HCC for nearly half a century. Moreover, recent clinical studies show that in patients of prostate cancer, lung cancer and Alzheimer’s disease, GOLPH2 expression is also up-regulated, suggesting that it may play a broad role in the development of diseases.We first found that GOLPH2 could repress the transcription of two subunit genes of interleukin-12(IL-12), p35 and p40. IL-12 plays a key role in promoting the differentiation of na?ve T helper(Th) cells into Th1 cells, which are crucial for cell-mediated immunity against intracellular pathogens and cancer. Therefore, we hypothesize that the up-regulated GOLPH2 could promote the development of tumorigenesis indirectly through the inhibition of IL-12.In order to investigate its functions further, we constructed a GOLPH2 knockout(KO) mouse strain by the TALEN technology. GOLPH2 KO mice displayed little difference from WT mice in gross appearance, behavior, blood cell account, physiological index and spleen cell composition.Because endotoxin-induced shock model has been widely used to study the acute inflammatory response, we constructed such a model by intraperitoneal injection of LPS and checked the concentration of major immune cytokines in the serum. We found higher levels of serum IL-12 in GOLPH2 KO mice compared with WT controls, this is in accordance with the experiment results in vitro.To assess the role of GOLPH2 in the immune activities of dendritic cells(DCs), we compared the mRNA expression profiles of LPS-activated WT and KO DCs derived from the bone marrow by next generation RNA-sequencing. Bioinformatic analyses of the sequencing data suggest that GOLPH2 may be involved in the regulation of extracellular matrix, cytoskeleton or other structural components.Our studies begin to reveal the potential role of GOLPH2 in the hematopoietic system and non-hematopoietic tissues, also lay the foundation for further investigation of GOLPH2’s multifaceted activities in normal and pathogenic conditions.