By virtue of its ability to regulate the composition of cerebrospinal fluid (CSF), the choroid plexus (CP) is ideally suited to instigate a rapid response to traumatic brain injury (TBI) by producing growth regulatory proteins. For example, Esophageal Cancer Related Gene-4 (Ecrg4) is a tumor suppressor gene that encodes a hormone-like peptide called augurin that is present in large concentrations in CP epithelia (CPe). Because augurin is thought to regulate senescence, neuroprogenitor cell growth and differentiation in the CNS, we evaluated the kinetics of Ecrg4 expression and augurin immunoreactivity in CPe after CNS injury. Adult rats were injured with a penetrating cortical lesion and alterations in augurin immunoreactivity were examined by immunohistochemistry. Ecrg4 gene expression was characterized by in situ hybridization. Cell surface augurin was identified histologically by confocal microscopy and biochemically by sub-cellular fractionation. Both Ecrg4 gene expression and augurin protein levels were decreased 24–72 hrs post-injury but restored to uninjured levels by day 7 post-injury. Protein staining in the supraoptic nucleus of the hypothalamus, used as a control brain region, did not show a decrease of auguin immunoreactivity. Ecrg4 gene expression localized to CPe cells, and augurin protein to the CPe ventricular face. Extracellular cell surface tethering of 14 kDa augurin was confirmed by cell surface fractionation of primary human CPe cells in vitro while a 6–8 kDa fragment of augurin was detected in conditioned media, indicating release from the cell surface by proteolytic processing. In rat CSF however, 14 kDa augurin was detected. We hypothesize the initial release and proteolytic processing of augurin participates in the activation phase of injury while sustained Ecrg4 down-regulation is dysinhibitory during the proliferative phase. Accordingly, augurin would play a constitutive inhibitory function in normal CNS while down regulation of Ecrg4 gene expression in injury, like in cancer, dysinhibits proliferation.
References
[1]
Rolls A, Shechter R, Schwartz M (2009) The bright side of the glial scar in CNS repair. Nat Rev Neurosci 10: 235–241.
[2]
Allan SM, Rothwell NJ (2003) Inflammation in central nervous system injury. Philos Trans R Soc Lond B Biol Sci 358: 1669–1677.
[3]
Romanko MJ, Rola R, Fike JR, Szele FG, Dizon ML, et al. (2004) Roles of the mammalian subventricular zone in cell replacement after brain injury. Prog Neurobiol 74: 77–99.
[4]
Zador Z, Stiver S, Wang V, Manley GT (2009) Role of aquaporin-4 in cerebral edema and stroke. Handb Exp Pharmacol 159–170.
[5]
Johanson C, Stopa E, McMillan P, Roth D, Funk J, et al. (2011) The distributional nexus of choroid plexus to cerebrospinal fluid, ependyma and brain: toxicologic/pathologic phenomena, periventricular destabilization, and lesion spread. Toxicol Pathol 39: 186–212.
[6]
Sharma HS, Zimmermann-Meinzingen S, Johanson CE (2010) Cerebrolysin reduces blood-cerebrospinal fluid barrier permeability change, brain pathology, and functional deficits following traumatic brain injury in the rat. Ann N Y Acad Sci 1199: 125–137.
[7]
Szmydynger-Chodobska J, Strazielle N, Zink BJ, Ghersi-Egea JF, Chodobski A (2009) The role of the choroid plexus in neutrophil invasion after traumatic brain injury. J Cereb Blood Flow Metab 29: 1503–1516.
[8]
Ghabriel MN, Zdziarski IM, Leigh C, Vink R (2010) Changes in the blood-CSF barrier in experimental traumatic brain injury. Acta Neurochir Suppl 106: 239–245.
[9]
Ennis SR, Keep RF (2006) The effects of cerebral ischemia on the rat choroid plexus. J Cereb Blood Flow Metab 26: 675–683.
[10]
Palm D, Knuckey N, Guglielmo M, Watson P, Primiano M, et al. (1995) Choroid plexus electrolytes and ultrastructure following transient forebrain ischemia. Am J Physiol 269: R73–79.
[11]
Chodobski A, Szmydynger-Chodobska J (2001) Choroid plexus: target for polypeptides and site of their synthesis. Microsc Res Tech 52: 65–82.
[12]
Johanson CE, Palm DE, Primiano MJ, McMillan PN, Chan P, et al. (2000) Choroid plexus recovery after transient forebrain ischemia: role of growth factors and other repair mechanisms. Cell Mol Neurobiol 20: 197–216.
[13]
Mirabeau O, Perlas E, Severini C, Audero E, Gascuel O, et al. (2007) Identification of novel peptide hormones in the human proteome by hidden Markov model screening. Genome Res 17: 320–327.
[14]
Gonzalez AM, Podvin S, Lin SY, Miller MC, Botfield H, et al. (2011) Ecrg4 expression and its product augurin in the choroid plexus: impact on fetal brain development, cerebrospinal fluid homeostasis and neuroprogenitor cell response to CNS injury. Fluids Barriers CNS 8: 6.
[15]
Kujuro Y, Suzuki N, Kondo T (2010) Esophageal cancer-related gene 4 is a secreted inducer of cell senescence expressed by aged CNS precursor cells. Proc Natl Acad Sci U S A 107: 8259–8264.
[16]
The gene paint website. Available: http://www.genepaint.org/cgi-bin/mgrqcgi？94?APPNAME=genepaint&PRGNAME=analysis_vi？ewer&ARGUMENTS=-AQ64622747128404,-AEG,-A？804,-Asetstart,-A5. Accessed 2011 Aug 26.
[17]
The Allen Brain Atlas Resources [Internet]. Seattle (WA): Allen Institute for Brain Science. ？2009. Available: http://www.brain-map.org. Last accessed 2011 Aug 26.
[18]
Ozawa A, Lick AN, Lindberg I (2011) Processing of proaugurin is required to suppress proliferation of tumor cell lines. Mol Endocrinol 25: 776–784.
[19]
Trudel C, Faure-Desire V, Florkiewicz RZ, Baird A (2000) Translocation of FGF2 to the cell surface without release into conditioned media. J Cell Physiol 185: 260–268.
[20]
Leadbeater WE, Gonzalez AM, Logaras N, Berry M, Turnbull JE, et al. (2006) Intracellular trafficking in neurones and glia of fibroblast growth factor-2, fibroblast growth factor receptor 1 and heparan sulphate proteoglycans in the injured adult rat cerebral cortex. J Neurochem 96: 1189–1200.
[21]
Roberton A, Gonzalez AM, Stopa EG, Leadbeater WE, Coimbra R, et al. (2009) Immunohistochemical evidence that argilin, the product of the ECRG4 gene, encodes a novel neuroendocrine peptide. Endocrine Abstracts, Society for Endocrinology BES 2009, Harrogate, UK 15: S82.
[22]
Johanson C, Stopa E, Baird A, Sharma H (2011) Traumatic brain injury and recovery mechanisms: peptide modulation of periventricular neurogenic regions by the choroid plexus-CSF nexus. J Neural Transm 118: 115–133.
[23]
Vanaja DK, Ehrich M, Van den Boom D, Cheville JC, Karnes RJ, et al. (2009) Hypermethylation of genes for diagnosis and risk stratification of prostate cancer. Cancer Invest 27: 549–560.
[24]
Mori Y, Ishiguro H, Kuwabara Y, Kimura M, Mitsui A, et al. (2007) Expression of ECRG4 is an independent prognostic factor for poor survival in patients with esophageal squamous cell carcinoma. Oncol Rep 18: 981–985.
[25]
Li LW, Yu XY, Yang Y, Zhang CP, Guo LP, et al. (2009) Expression of esophageal cancer related gene 4 (ECRG4), a novel tumor suppressor gene, in esophageal cancer and its inhibitory effect on the tumor growth in vitro and in vivo. Int J Cancer 125: 1505–1513.
[26]
Su T, Liu H, Lu S (1998) [Cloning and identification of cDNA fragments related to human esophageal cancer]. Zhonghua Zhong Liu Za Zhi 20: 254–257.
[27]
Yue CM, Deng DJ, Bi MX, Guo LP, Lu SH (2003) Expression of ECRG4, a novel esophageal cancer-related gene, downregulated by CpG island hypermethylation in human esophageal squamous cell carcinoma. World J Gastroenterol 9: 1174–1178.
[28]
Tadross JA, Patterson M, Suzuki K, Beale KE, Boughton CK, et al. (2010) Augurin stimulates the hypothalamo-pituitary-adrenal axis via the release of corticotrophin-releasing factor in rats. Br J Pharmacol 159: 1663–1671.
[29]
Norton WT (1999) Cell reactions following acute brain injury: a review. Neurochem Res 24: 213–218.
[30]
Qureshi IA, Mehler MF (2010) Emerging role of epigenetics in stroke: part 1: DNA methylation and chromatin modifications. Arch Neurol 67: 1316–1322.
[31]
Ibrahimi OA, Zhang F, Hrstka SC, Mohammadi M, Linhardt RJ (2004) Kinetic model for FGF, FGFR, and proteoglycan signal transduction complex assembly. Biochemistry 43: 4724–4730.
[32]
Boulougouris P, Elder J (2001) Epidermal growth factor receptor structure, regulation, mitogenic signalling and effects of activation. Anticancer Res 21: 2769–2775.
[33]
Popovic M, Bella J, Zlatev V, Hodnik V, Anderluh G, et al. (2011) The interaction of Jagged-1 cytoplasmic tail with afadin PDZ domain is local, folding-independent, and tuned by phosphorylation. J Mol Recognit 24: 245–253.
[34]
Blits-Huizinga CT, Nelersa CM, Malhotra A, Liebl DJ (2004) Ephrins and their receptors: binding versus biology. IUBMB Life 56: 257–265.
[35]
Li Y, Chen J, Chopp M (2002) Cell proliferation and differentiation from ependymal, subependymal and choroid plexus cells in response to stroke in rats. J Neurol Sci 193: 137–146.
[36]
Kernie SG, Parent JM (2010) Forebrain neurogenesis after focal Ischemic and traumatic brain injury. Neurobiol Dis 37: 267–274.
[37]
Clarke WE, Berry M, Smith C, Kent A, Logan A (2001) Coordination of fibroblast growth factor receptor 1 (FGFR1) and fibroblast growth factor-2 (FGF-2) trafficking to nuclei of reactive astrocytes around cerebral lesions in adult rats. Mol Cell Neurosci 17: 17–30.
[38]
Logan A, Frautschy SA, Gonzalez AM, Sporn MB, Baird A (1992) Enhanced expression of transforming growth factor beta 1 in the rat brain after a localized cerebral injury. Brain Res 587: 216–225.
[39]
Logan A, Berry M, Gonzalez AM, Frautschy SA, Sporn MB, et al. (1994) Effects of transforming growth factor beta 1 on scar production in the injured central nervous system of the rat. Eur J Neurosci 6: 355–363.
[40]
Logan A, Frautschy SA, Gonzalez AM, Baird A (1992) A time course for the focal elevation of synthesis of basic fibroblast growth factor and one of its high-affinity receptors (flg) following a localized cortical brain injury. J Neurosci 12: 3828–3837.
[41]
Baird A, Eliceiri BP, Gonzalez AM, Johanson CE, Leadbeater W, et al. (2011) Targeting the choroid plexus-CSF-brain nexus using peptides identified by phage display. Methods Mol Biol 686: 483–498.
