Milk Fat Globule Protein Epidermal Growth Factor-8

Abstract

Abstract-Advancing age induces aortic wall thickening that results from the concerted effects of numerous signaling proteins, many of which have yet to be identified. To search for novel proteins associated with aortic wall thickening, we have performed a comprehensive quantitative proteomic study to analyze aortic proteins from young (8 months) and old (30 months) rats and identified 50 proteins that significantly change in abundance with aging. One novel protein, the milk fat globule protein epidermal growth factor 8 (MFG-E8), increases 2.3-fold in abundance in old aorta. Transcription and translation analysis demonstrated that aortic MFG-E8 mRNA and protein levels increase with aging in several mammalian species including humans. Dual immunolabeling shows that MFG-E8 colocalizes with both angiotensin II and monocyte chemoattractant protein (MCP)-1 within vascular smooth muscle cells (VSMCs) of the thickened aged aortic wall. Exposure of early passage VSMCs from young aorta to angiotensin II markedly increases MFG-E8 and enhances invasive capacity to levels observed in VSMCs from old rats. Treatment of VSMCs with MFG-E8 increases MCP-1 expression and VSMCs invasion that are inhibited by the MCP-1 receptor blocker vCCI. Silencing MFG-E8 RNA substantially reduces MFG-E8 expression and VSMCs invasion capacity.The data indicate that arterial MFG-E8 significantly increases with aging and is a pivotal relay element within the angiotensin II/MCP-1/VSMC invasion signaling cascade. Thus, targeting of MFG-E8 within this signaling axis pathway is a potential novel therapy for the prevention and treatment of the age-associated vascular diseases such as atherosclerosis. Key Words: MFG-E8 Ⅲ angiotensin II Ⅲ monocyte chemoattractant protein-1 Ⅲ vascular smooth muscle cells Ⅲ aging P roinflammatory processes and associated elevated invasion capacity of vascular smooth muscle cells (VSMCs) are increased within the diffuse thickening of the arterial wall that evolves with advancing age. [1][2][3][4] In humans, this ageassociated arterial remodeling is an independent risk factor for the epidemic of quintessential human cardiovascular diseases, ie, atherosclerosis, hypertension, and stroke. 1,3,5,6 The age-associated arterial wall thickening and other aspects of arterial remodeling are evolutionarily conserved in various mammalian species, including rodents, nonhuman primates, and humans. 1,3,[7][8][9][10][11][12][13][14] The thickened arterial intima is formed because of VSMCs invasion and proliferation and is not limited to secretion within the subendothelial space. 2,3,7,14 A growing body of evidence indicates that VSMCs within the arterial media begin to express and activate proteases such as matrix metalloprotease (MMP)2 and calpain-1, which enable cytoskeletal remodeling and degradation of (1) basement membranes that surround VSMCs, (2) adjacent matrix, and (3) elastic lamina. Thus VSMCs invasion into the subendothelial space is driven, at least in part, by angiotensin (Ang) Original received September 8, 2008; revision re...

Decreased S -Nitrosylation of Tissue Transglutaminase Contributes to Age-Related Increases in Vascular Stiffness

“…It is interesting to note that the abundance of TG2 remained unchanged in both aging human and rat aorta, an observation supported by a recent proteomic study identifying age-associated alterations in protein expression levels in rat aorta. 31 This highlights the importance of nitrosoredox-dependent posttranslational modifications in determining function and their role in human disease 32 and stresses the critical role of functional proteomics in target identification. TG2 Ϫ/Ϫ mice do not show any overt cardiovascular phenotype when unchallenged, but have altered response(s) compared to WT littermates under several stresses.…”

S100A11 Mediates Hypoxia-induced Mitogenic Factor (HIMF)-induced Smooth Muscle Cell Migration, Vesicular Exocytosis, and Nuclear Activation

“…After HIMF treatment for 5 min, cells were immediately washed twice with cold phosphate-buffered saline (PBS) and then lysed with isoelectric focusing (IEF) lysis buffer comprising 8 M urea, 2 M thiourea, 4% CHAPS, and 50 mM dithiothreitol (DTT) and centrifuged at 16,000 ϫ g for 15 min at 4°C (9). The supernatant was snap frozen and stored at Ϫ80°C.…”

Calorie Restriction Curbs Proinflammation That Accompanies Arterial Aging, Preserving a Youthful Phenotype

“…PDGF‐BB is not only a potent mitogen, but also a strong chemoattractant of VSMCs, creating a permissive tissue microenvironment for VSMC migration and invasion, promoting formation of a thickened intima in vivo 1, 2, 3, 8, 41, 42. Prior findings indicate that PDGF‐BB treatment induces invasion and migration of old VSMCs in vitro 8, 9.…”