But no alteration in brown adipose tissue mass. This could indicate a possible role for MIC-1/GDF15 in inhibition of lipid formation and/or accumulation. However the increase in adiposity MIC-12/2 mice is more likely to have developed because of increase in food intake, at least in female mice. Whilst in male mice, we could not identify significant alteration in food intake, small differences, significant enough to alter body weight and compositions could still exist but are beyond our capacity to detect in this study. MIC-1/GDF15 was first identified as an appetite regulator when it was discovered that its overexpression in cancer and otherdiseases lead to anorexia/cachexia. The data in this study indicates that under physiological conditions, MIC-1/GDF15 also plays a small role in the regulation of energy intake and expenditure, with greater effects in females than in males. Thus it would appear that diseases associated with marked increases in MIC-1/GDF15 expression subvert a normal physiological pathway to cause anorexia/cachexia. A better understanding of this pathway is important for a complete understanding of energy homeostasis and more effective therapy of the anorexia/cachexia syndrome.Author ContributionsConceived and designed the experiments: VWT LM HJ TK SBJ SL HH DAB AS SNB. Performed the experiments: VWT LM HJ TK RM 
KKML HZ LW CPM LJ YH. Analyzed the data: VWT LM HJ TK RM DAB AS SNB. Contributed reagents/materials/analysis tools: CPM. Wrote the paper: VWT DAB AS SNB.
Macromolecular drugs including therapeutic peptides and biologicals such as insulin and vaccines are the preferred therapies for various systemic diseases 1]. However, owing to their proteolytic degradation in the gastrointestinal tract and poor permeation across the intestinal epithelium, all therapeutic macromolecules suffer from poor oral bioavailability and thus have to be administered via parenteral route 2,3]. Parenteral route, though effective in administration of therapeutics, suffers from severe limitations including pain, needle-phobia and poor patient compliance. Hence, significant attention is being dedicated to the development of orally administered formulations of biologics 4?]. Owing to the challenges and Epigenetics complexity of in vivo models of oral absorption, in vitro experimental models that allow assessment and/or prediction of oral bioavailability play a vital role in development of oral biologics. Several experimental models have been developed for predicting intestinal permeability including in situ isolated perfused intestinal systems, everted gut sac and cultured cell monolayers8]. Among these, Caco-2 cell monolayers are one of the most Epigenetic Reader Domain studied 18204824 approaches for predicting oral absorption of therapeutic peptides, and are considered the gold standard for predicting in vitro intestinal permeability and absorption 9?2]. Caco-2 is a human colon carcinoma cell line, which when grown on permeable filter supports, grows into monolayers with differentiated phenotypes exhibiting many salient features of small intestinal villus epithelium, the most important ones being development of intercellular tight junctions and inclusion of various metabolic enzymes present in the intestinal 
epithelium. Caco-2 cell lines have been widely used to predict oral absorption of novel therapeutic agents during early stages of development. A conventional fully differentiated and confluent Caco-2 monolayer development requires about 3 weeks to culture with 9?0 labor-intensive.But no alteration in brown adipose tissue mass. This could indicate a possible role for MIC-1/GDF15 in inhibition of lipid formation and/or accumulation. However the increase in adiposity MIC-12/2 mice is more likely to have developed because of increase in food intake, at least in female mice. Whilst in male mice, we could not identify significant alteration in food intake, small differences, significant enough to alter body weight and compositions could still exist but are beyond our capacity to detect in this study. MIC-1/GDF15 was first identified as an appetite regulator when it was discovered that its overexpression in cancer and otherdiseases lead to anorexia/cachexia. The data in this study indicates that under physiological conditions, MIC-1/GDF15 also plays a small role in the regulation of energy intake and expenditure, with greater effects in females than in males. Thus it would appear that diseases associated with marked increases in MIC-1/GDF15 expression subvert a normal physiological pathway to cause anorexia/cachexia. A better understanding of this pathway is important for a complete understanding of energy homeostasis and more effective therapy of the anorexia/cachexia syndrome.Author ContributionsConceived and designed the experiments: VWT LM HJ TK SBJ SL HH DAB AS SNB. Performed the experiments: VWT LM HJ TK RM KKML HZ LW CPM LJ YH. Analyzed the data: VWT LM HJ TK RM DAB AS SNB. Contributed reagents/materials/analysis tools: CPM. Wrote the paper: VWT DAB AS SNB.
Macromolecular drugs including therapeutic peptides and biologicals such as insulin and vaccines are the preferred therapies for various systemic diseases 1]. However, owing to their proteolytic degradation in the gastrointestinal tract and poor permeation across the intestinal epithelium, all therapeutic macromolecules suffer from poor oral bioavailability and thus have to be administered via parenteral route 2,3]. Parenteral route, though effective in administration of therapeutics, suffers from severe limitations including pain, needle-phobia and poor patient compliance. Hence, significant attention is being dedicated to the development of orally administered formulations of biologics 4?]. Owing to the challenges and complexity of in vivo models of oral absorption, in vitro experimental models that allow assessment and/or prediction of oral bioavailability play a vital role in development of oral biologics. Several experimental models have been developed for predicting intestinal permeability including in situ isolated perfused intestinal systems, everted gut sac and cultured cell monolayers8]. Among these, Caco-2 cell monolayers are one of the most studied 18204824 approaches for predicting oral absorption of therapeutic peptides, and are considered the gold standard for predicting in vitro intestinal permeability and absorption 9?2]. Caco-2 is a human colon carcinoma cell line, which when grown on permeable filter supports, grows into monolayers with differentiated phenotypes exhibiting many salient features of small intestinal villus epithelium, the most important ones being development of intercellular tight junctions and inclusion of various metabolic enzymes present in the intestinal epithelium. Caco-2 cell lines have been widely used to predict oral absorption of novel therapeutic agents during early stages of development. A conventional fully differentiated and confluent Caco-2 monolayer development requires about 3 weeks to culture with 9?0 labor-intensive.
