Complete lack of vitamin C intake generates pulmonary emphysema in senescence marker protein-30 knockout mice

Abstract

Vitamin C (VC) is a potent antioxidant and plays an essential role in collagen synthesis. As we previously reported, senescence marker protein-30 (SMP30) knockout (KO) mice cannot synthesize VC due to the genetic disruption of gluconolactonase (i.e., SMP30). Here, we utilized SMP30 KO mice deprived of VC and found that VC depletion caused pulmonary emphysema due to oxidative stress and a decrease of collagen synthesis by the third month of age. We grew SMP30 KO mice and wild-type (WT) mice on VC-free chow and either VC water [VC(ϩ)] or plain water [VC(Ϫ)] after weaning at 4 wk of age. Morphometric findings and reactive oxygen species (ROS) in the lungs were evaluated at 3 mo of age. No VC was detected in the lungs of SMP30 KO VC(Ϫ) mice, but their ROS increased 50.9% over that of the VC(ϩ) group. Moreover, their collagen content in the lungs markedly decreased, and their collagen I mRNA decreased 82.2% compared with that of the WT VC(Ϫ) group. In the SMP30 KO VC(Ϫ) mice, emphysema developed [21.6% increase of mean linear intercepts (MLI) and 42.7% increase of destructive index compared with VC(ϩ) groups], and the levels of sirtuin 1 (Sirt1) decreased 16.8%. However, VC intake increased the MLI 16.2% and thiobarbituric acid reactive substances 22.2% in WT mice, suggesting that an excess of VC can generate oxidative stress and may be harmful during this period of lung development. These results suggest that VC plays an important role in lung development through affecting oxidant-antioxidant balance and collagen synthesis. chronic obstructive pulmonary disease; collagen VITAMIN C (VC) is a water-soluble, hexonic sugar acid that has two dissociable protons (40) and is abundant in fluids of the lung epithelial lining (50). VC scavenges free radicals such as superoxide (34), singlet oxygen (4), and hydroxyl radicals (2). Several reports indicate that VC has a beneficial effect on lung function but, when depleted during aging, may promote chronic obstructive pulmonary disease (COPD; Refs. 41, 44). On the other hand, VC also plays an essential role in collagen synthesis because it acts as a cofactor for prolyl hydroxylase to catalyze hydroxyproline synthesis, which is involved in collagen helix stabilization (33, 38). Furthermore, VC stimulates collagen biosynthesis not only by promoting the activity of the prolyl hydroxylase, but also by increasing the mRNA of collagen (I and III; Refs. 13,35).Senescence marker protein-30 (SMP30) is characterized by its ever-decreasing content in the liver, kidney, and lung with aging, a decrease that is androgen-independent (11). To clarify the physiological role of SMP30 in age-associated organ disorders, we used gene targeting to establish the SMP30 knockout (KO) mouse from C57BL/6 mice (17). Recently, we (24) reported that SMP30 has gluconolactonase (GNL) activity. Since GNL is a key enzyme in the VC biosynthetic pathway of mammals, mice deprived of GNL (SMP30 KO mice) lack the ability to synthesize VC (19). We (42) further discovered that oxidative stress is greater in the lungs o...

SIRT1 protects against emphysema via FOXO3-mediated reduction of premature senescence in mice

“…Hence, SIRT1 activation downregulated SIPS through FOXO3/p21 pathway, thereby protecting against emphysema. In addition to FOXO3, recent studies have demonstrated the involvement of other developmental and senescence-related genes, such as Wnt/β-catenin, Notch, Klotho, senescence marker protein-30, and Werner syndrome protein, in the development of emphysema (55)(56)(57)(58)(59)(60). However, it remains to be seen whether SIRT1 targets these genes in response to CS exposure.…”

Role of histone deacetylase 2 in epigenetics and cellular senescence: implications in lung inflammaging and COPD

“…It is also likely that carbonyls/oxidants generated or present in cigarette smoke cause immunosenescence of T-and B-cells, leading to abnormal recognition of self-antigens, which is important for the development of COPD (14,54,62,90,109). The involvement of cellular senescence in the pathogenesis of emphysema is also shown in various studies using genetically altered mouse strains (55,64,108,112,139). However, the molecular mechanisms that underlie cigarette smoke-induced cellular senescence in vitro in lung cells and in vivo in mouse lung and the precise role of SIPS in the development of COPD/emphysema are unclear.…”

Vitamin C Protected Human Retinal Pigmented Epithelium from Oxidant Injury Depending on Regulating SIRT1

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