붉은불개미는 남미가 원산인 외래해충으로써 기후변화로 인한 기온 상승과 국가간 교역량의 증가를 통해 전세계적으로 서식범위를 확장해 나가고 있다. 국내에서는 붉은불개미가 2017년 9월 부산 감만항에서 처음 발견된 이후 올해까지 4차례 추가로 발견되어 국내 침입 및 정착 가능성이 점차 증가하고 있다. 곤충에서 인슐린 신호체계는 일반적으로 산란, 생장 및 발육, 대사계, 스트레스 저항성에 관여하는 것으로 널리 알려져 있다. 본 연구에서는 붉은불개미의 인슐린에 대한 생물학적인 기능을 이해하기 위해 인슐린 수용체(insulin receptor)의 발현을 억제한 후 나타나는 생리적 변화를 관찰하였다. 그 결과 체내빙결점(supercooling point)에 영향을 미쳐 붉은불개미의 저온생리에 영향을 준다는 것을 확인할 수 있었다.

Previously we have succeeded to isolate stem cells (HEAC) from human eyelid adipose tissue, and functionally differentiate them into insulin-secreting cells. In the present study, we examined whether insulin family members might affect the insulinogenic differentiation of HEAC. Insulin treatment during culture affected little on the insulin and c-peptide secretions from HEAC after culture. However, insulin-like growth factor (IGF) 1 treatment decreased both secretions, whereas IGF2 greatly increased the secretions in a glucose-dependent manner. HEAC treated with IGF2 showed stronger expression of Pdx1, Isl1, Pax6 and PC1/3 genes compared to the control. They also showed distinct staining with insulin and c-peptide antibodies, and dithizone. While insulin or IGF2 treatment increased total cell number by 1.3- or 1.5-fold, respectively, each treatment increased the amount of insulin secretion by 27.1- or 78.1-fold, respectively. IGF2-enhanced insulinogenic differentiation was completely blocked by an antibody against insulin receptor (IR), but not by an antibody against IGF1 receptor (IGF1R). Differentiated HEAC showed expression of both IR and IGF1R genes while they expressed neither IGF2 nor IGF2R genes. Based upon these results, it is suggested that whereas IGF1 might inhibit the insulinogenic differentiation of HEAC, insulin and IGF2 could enhance the differentiation, and that the enhancing effect could be mediated via IR.