An Epidermal-Specific Role for Arginase1 during Cutaneous Wound Repair
Rachel A. CromptonHelen WilliamsLaura CampbellHui Kheng LimCharis R. SavilleDavid M. AnsellAdam J. ReidJason WongLeah A. VardyMatthew J. HardmanSheena M. Cruickshank
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Polyamine
Catabolism
Ornithine aminotransferase
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Wound healing is an important issue that influences quality of life, and the need for products associated with wound healing is growing annually. New materials and therapies for skin wounds are being continuously researched and developed in order to increase treatment efficacy. Here, we show that the peptide AES16-2M comprised of five short amino acid sequences (REGRT) demonstrates efficacy in wound healing. AES16-2M exerted more effective healing than the control in an acute wound model, and tissue regeneration was similar to that of normal tissue in AES16-2M-treated skin. We found that the increase in re-epithelialization by AES16-2M early in wound development was due to migration of keratinocytes; a scratch assay using a human keratinocyte cell line (HaCaT) also demonstrated effective wound closure by AES16-2M. The migration of keratinocytes effected by AES16-2M was promoted through ERK phosphorylation and blocked with U0126, an ERK inhibitor. Moreover, AES16-2M treatment stimulated human dermal fibroblast (HDF) migration as well as keratinocyte. Taken together, these results suggest that AES16-2M can be an effective therapeutic agent for wound healing by promoting migration of keratinocytes and fibroblasts via ERK phosphorylation.
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Proliferation and migration of keratinocytes are vital processes for the successful epithelization specifically after wounding. MiR-221 has been identified to play a potential role in promoting wound regeneration by inducing blood vessel formation. However, little is known about the role of miR-221 in the keratinocyte proliferation and migration during wound healing. An in vivo mice wound-healing model was generated; the expression levels of miR-221 were assessed by qRT-PCR and fluorescence in situ hybridization. Initially, we found that miR-221 was upregulated in the proliferative phase of wound healing. Further, in an in vivo wound-healing mice model, targeted delivery of miR-221 mimics accelerated wound healing. Contrastingly, inhibition of miR-221 delayed healing. Additionally, we observed that overexpression of miR-221 promoted cell proliferation and migration, while inhibition of miR-221 had the opposite effects. Moreover, we identified SOCS7 as a direct target of miR-221 in keratinocytes and overexpression of SOCS7 reversed the effects of miR-221 in HaCaT keratinocytes. Finally, we identified that YB-1 regulates the expression of miR-221 in HaCaT keratinocytes. Overall, our experiments suggest that miR-221 is regulated by YB-1 in HaCaT keratinocytes and acts on SOCS7, thereby playing an important role in HaCaT keratinocyte proliferation and migration during wound healing.
HaCaT
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Background and purpose: L-arginine is a substrate for arginase, and is also a source of nitric oxide that mediates hypotension in septic shock. The possibility of arginase protection against septic shock was studied. Methods: For experiments of single-dose intravenous injection with arginase A1 (5 μg/mouse), various doses of Escherichia coli (E. coli) were simultaneously injected into the intraperitoneum of each BALB/c mouse. The survival rates were observed for three days. For experiments with multiple-dose injections of arginase, mice were intravenous injected with arginase A1 (5 μg/day/mouse) daily from day 1 to day 4, and E. coli was introduced on day 3. Results: For experiments with multiple doses of arginase A1, when each mouse was injected with E. coli at a dose of 1.6 × 107 colony forming units, they were significantly protected from death by the effect of arginase (P = 0.008). This protection was arginase-dose related and was not a result of direct inhibition by arginase on bacterial growth, or by the presence of L-arginine-degradation products, L-ornithine and urea. Single injection of arginase did not confer a significant protection. Conclusion: Multiple injections of arginase A1 do protect E. coli-induced mice to some extent from death of septic shock, while single injection of arginase did not.
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Activated macrophages avidly consume arginine via the action of inducible nitric oxide synthase (iNOS) and/or arginase. In contrast to our knowledge regarding macrophage iNOS expression, the stimuli and mechanisms that regulate expression of the cytosolic type I (arginase I) or mitochondrial type II (arginase II) isoforms of arginase in macrophages are poorly defined. We show that one or both arginase isoforms may be induced in the RAW 264.7 murine macrophage cell line and that arginase expression is regulated independently of iNOS expression. For example, 8-bromo-cAMP strongly induced both arginase I and II mRNAs but not iNOS. Whereas interferon-γ induced iNOS but not arginase, 8-bromo-cAMP and interferon-γ mutually antagonized induction of iNOS and arginase I mRNAs. Dexamethasone, which did not induce either arginase or iNOS, almost completely abolished induction of arginase I mRNA by 8-bromo-cAMP but enhanced induction of arginase II mRNA. Lipopolysaccharide (LPS) induced arginase II mRNA, but 8-bromo-cAMP plus LPS resulted in synergistic induction of both arginase I and II mRNAs. In all cases, increases in arginase mRNAs were sufficient to account for the increases in arginase activity. These complex patterns of expression suggest that the arginase isoforms may play distinct, although partially overlapping, functional roles in macrophage arginine metabolism.
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Mammals express two isoforms of arginase, designated types I and II. Arginase I is a component of the urea cycle, and inherited defects in arginase I have deleterious consequences in humans. In contrast, the physiologic role of arginase II has not been defined, and no deficiencies in arginase II have been identified in humans. Mice with a disruption in the arginase II gene were created to investigate the role of this enzyme. Homozygous arginase II-deficient mice were viable and apparently indistinguishable from wild-type mice, except for an elevated plasma arginine level which indicates that arginase II plays an important role in arginine homeostasis.
Argininosuccinate synthase
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Ornithine aminotransferase
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Keratinocyte proliferation and migration are crucial steps during skin wound healing. The functional role of microRNAs (miRs) remains relatively unknown during this process. miR-93 levels have been reported to increase within 24 h of skin wound healing; however, whether miR-93-3p or miR-93-5p plays a specific role in wound healing is yet to be studied. In this study, with the use of an in vivo mouse skin wound-healing model, we demonstrate that miR-93-3p is significantly upregulated, whereas there is no change in the expression of miR-93-5p during skin wound healing. In HaCaT cells, miR-93-3p overexpression increased proliferation and migration of the cells, whereas miR-93-3p inhibition had the reverse effect. Additionally, it was evident that ZFP36L1 was a direct target of miR-93-3p in keratinocytes. Further, ZFP36L1 silencing mirrored the consequences observed during miR-93-3p overexpression on both proliferation and migration of keratinocytes. In addition, we demonstrate that zinc-finger X-linked (ZFX), as a target for ZFP36L1, is involved in the promotion of the miR-93-3p/ZFP36L1 axis in keratinocyte proliferation and migration. Ultimately, we found that mouse skin wound model treatment with anti-miR-93-3p delayed wound healing. Overall, our results show that miR-93-3p is a crucial regulator of skin wound healing that facilitates keratinocyte proliferation and migration through ZFP36L1/ZFX axis. Keratinocyte proliferation and migration are crucial steps during skin wound healing. The functional role of microRNAs (miRs) remains relatively unknown during this process. miR-93 levels have been reported to increase within 24 h of skin wound healing; however, whether miR-93-3p or miR-93-5p plays a specific role in wound healing is yet to be studied. In this study, with the use of an in vivo mouse skin wound-healing model, we demonstrate that miR-93-3p is significantly upregulated, whereas there is no change in the expression of miR-93-5p during skin wound healing. In HaCaT cells, miR-93-3p overexpression increased proliferation and migration of the cells, whereas miR-93-3p inhibition had the reverse effect. Additionally, it was evident that ZFP36L1 was a direct target of miR-93-3p in keratinocytes. Further, ZFP36L1 silencing mirrored the consequences observed during miR-93-3p overexpression on both proliferation and migration of keratinocytes. In addition, we demonstrate that zinc-finger X-linked (ZFX), as a target for ZFP36L1, is involved in the promotion of the miR-93-3p/ZFP36L1 axis in keratinocyte proliferation and migration. Ultimately, we found that mouse skin wound model treatment with anti-miR-93-3p delayed wound healing. Overall, our results show that miR-93-3p is a crucial regulator of skin wound healing that facilitates keratinocyte proliferation and migration through ZFP36L1/ZFX axis.
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