Expression of the adrenomedullin binding protein, complement factor H, in the pancreas and its physiological impact on insulin secretion

Abstract

Adrenomedullin (AM) is a ubiquitous peptide hormone which, among other functional roles, reduces insulin secretion in the pancreas. Recently we have described the interaction between AM and the complement regulator protein factor H, which results in mutual modulation of their respective functions. Here we identify the expression of factor H in the cells of the rat pancreatic islets by immunohistochemistry and multiple immunofluorescence followed by confocal microscopy. In addition, double immunogold staining under the electron microscope showed coexistence of insulin and factor H immunoreactivities within the same secretory granules; interestingly, factor H staining was found in the electron-lucent haloes whereas the insulin antibody labeled preferentially the dense cores. The existence of factor H mRNA in the pancreas was confirmed by RT-PCR and in situ hybridization. The function of factor H in the pancreas was investigated with an insulin secretion assay. Addition of factor H to freshly isolated islets in the presence of AM resulted in a further reduction in insulin secretion with a concomitant elevation of cAMP, suggesting that factor H increases AM function in glucose homeostasis. The expression of factor H in the pancreas may play other important roles such as protection against complementmediated cell lysis.

Transgenic expression of human thymidylate synthase accelerates the development of hyperplasia and tumors in the endocrine pancreas

“…Isolation of islets from exocrine pancreas Pancreatic islets were isolated from four TS þ /À transgenic mice and four wild-type FVB mice as described previously (Martinez et al, 2001). Each mouse was perfused through the heart with Hank's balanced salt solution (HBSS, Sigma) to remove blood from the pancreatic vessels.…”

Adrenomedullin (AM) and adrenomedullin binding protein (AM-BP) in the bovine mammary gland and milk: Effects of stage of lactation and experimental intramammary E. coli infection

“…Examples of activity include its capacity to ameliorate regional ischemic events and blood shunting during sepsis by maintaining local tissue oxygen perfusion and blood flow [43], reducing tissue necrosis and apoptosis through AM/AM-BP complex-augmented production of anti-apoptotic BCL-2 cascade factors and concomitantly decreased pro-apoptotic Bax gene expression [44], effects on pancreatic hormone secretion and localized tissue metabolic responses to pancreatic hormones [13,29,30], interactions with the LPS-TNF-␣-nitric oxide cascade [12,13,38], and its effects to neutralize growth and pathogenic activities of both Gram-negative and Gram-positive [8][9][10] bacteria.…”

“…Previous data derived from mass spectroscopy proteomic analysis of isolated and purified AM-BP has demonstrated that AM-BP and complement factor-H are one and the same [17], and that the initial localization and quantification of AM-BP by 125 I-AM ligand blot [16] coincided with that derivable using Western blot analysis based on antibody against C-F H [30]. Therefore, milk levels of AM-BP were measured by Western blot using rabbit antihuman C-F H (Serotec, Raleigh, NC) as the primary antibody.…”

“…Antibodies for AM and AM-BP immunohistochemistry were rabbit anti-AM (P-072, 1:1000 dilution; [29]) and rabbit anti-human C-F H (Serotec, Raleigh, NC, 1:2000 dilution; [30]). Mammary biopsy samples were embedded in paraffin, sectioned at 5 m and mounted on glass slides.…”

Relationship Between Obesity and Immune System a Review Article

“…Basal levels of complement activation have rather beneficial metabolic effects, ranging from stimulation of insulin secretion in pancreatic β-cells (ASP, fH) [41,42] to insulin-like actions with regard to adipocyte maturation and energy regulation (adipsin, ASP, C3a, C5a) [43]. In contrast, increased complement action can contribute to metabolic pathology.…”