Differential expression of chaperonin containing T-complex polypeptide (CCT) subunits during fetal and adult skin wound healing

CCTδ colocalizes with actin and β-tubulin: Insight into its involvement in the cytoskeleton formation of the intracellular parasite Nosema bombycis

The chaperonin-containing t-complex polypeptide 1 (CCT) is a molecular chaperone protein that is widely present in eukaryotic cytoplasm and can assist in the folding of newly synthesized proteins. The CCT complex consists of eight completely different subunits, among which the δ subunit plays an extremely important role in the folding and assembly of cytoskeleton proteins as an individual or complex with other subunits. In this study, we identified the CCTδ in the microsporidian Nosema bombycis (NbCCTδ) for the first time. The NbCCTδ gene contains a complete ORF of 1497 bp in length that encodes a 498 amino acid polypeptide. NbCCTδ is expressed throughout the entire lifecycle of N. bombycis and rather higher in early stage of proliferation. Indirect immunofluorescence results showed that NbCCTδ was colocalized with actin and β-tubulin during the proliferative and sporogonic phases of N. bombycis. RNA interference down-regulated the expression of the NbCCTδ gene. These results imply that NbCCTδ may participate in cytoskeleton formation and proliferation of N. bombycis.

Local Probiotic Therapy with Lactobacillus plantarum Mitigates Scar Formation in Rabbits after Burn Injury and Infection

BACKGROUND

Infection is the most common complication in burn-injured patients and is believed to contribute to the hypertrophic scarring frequently observed in such injury. Pseudomonas aeruginosa is a common pathogen in burn wound infection. We examined the effect of local probiotic therapy with Lactobacillus plantarum on the severity of the scarring following burn wounding and infection with P. aeruginosa in a rabbit model.

METHODS

Full-thickness burn wounds were inoculated with control vehicle or L. plantarum; wounds were then challenged with bioluminescent P. aeruginosa. The time course of the ensuing infection was monitored by quantification of the emitted light. After allowing wounds to contract to near completion, they were harvested and analyzed for markers of scar formation.

RESULTS

Application of L. plantarum curtailed both the severity and the length of the pseudomonal infection. Probiotic therapy significantly reduced both Type I collagen mRNA concentrations and total collagen protein accumulation in infected wounds, consistent with reduced scarring. Surprisingly, the probiotic showed a nearly equivalent effect in uninfected wounds. Masson's trichrome staining confirmed these findings histologically.

CONCLUSIONS

Lactobacillus plantarum shows exciting potential as a therapeutic agent to both counteract burn wound infection and to alleviate scarring even in the absence of infection.

Chaperonin containing T-complex polypeptide subunit eta is a potential marker of joint contracture: an experimental study in the rat

Joint contracture is a fibroproliferative disorder that restricts joint mobility, resulting in tissue degeneration and deformity. However, the etiology of joint contracture is still unknown. Chaperonin containing T-complex polypeptide subunit eta (CCT-eta) is reported to increase in fibrotic diseases. The purpose of this study was to investigate whether CCT-eta is implicated in joint contracture and to determine the role of CCT-eta in the progression of joint contracture by analyzing a rat model. We immobilized the left knee joint of rat by internal fixation for 8 weeks. The non-immobilized right leg served as a control. The range of motion (ROM) of the knee was investigated. Fibroblasts were obtained from the posterior joint capsule of the joints. The outcome was followed by quantitative real-time polymerase chain reaction (qRT-PCR), Western blot, fibroblast migration assay, and collagen assay. The effect of CCT-eta on the functions of fibroblasts was observed by utilizing a short inhibitory RNA (siRNA) targeting CCT-eta. The ROM of the immobilized joints was significantly limited compared to the contralateral joints (p < 0.05). Fibroblasts derived from the contractive joints showed higher mRNA and protein expressions of CCT-eta in parallel with alpha-smooth muscle actin (α-SMA) compared to the cells from the contralateral knees (p < 0.05). siRNA-mediated downregulation of CCT-eta inhibited the expressions of both CCT-eta and α-SMA. Moreover, the reduction of CCT-eta also significantly decreased fibroblast functions such as cell mobility and collagen synthesis (all p < 0.05). Our findings indicate that CCT-eta appears to be a potential marker of joint contracture disease.

The chaperonin CCTα is required for efficient transcription and replication of rabies virus

Negri bodies (NBs) are formed in the cytoplasm of rabies virus (RABV)-infected cells and are accompanied by a number of host factors to NBs, in which replication and transcription occur. Here, it was found that chaperonin containing TCP-1 subunit alpha (CCTα) relocalizes to NBs in RABV-infected cells, and that cotransfection of nucleo- and phospho-proteins of RABV is sufficient to recruit CCTα to the NBs' structure. Inhibition of CCTα expression by specific short hairpin RNA knockdown inhibited the replication and transcription of RABV. Therefore, this study showed that the host factor CCTα is associated with RABV infection and is very likely required for efficient virus transcription and replication.

Increased CCT-eta expression is a marker of latent and active disease and a modulator of fibroblast contractility in Dupuytren's contracture

Dupuytren's contracture (DC) is a fibroproliferative disorder of unknown etiology characterized by a scar-like contracture that develops in the palm and/or digits. We have previously reported that the eta subunit of the chaperonin containing T-complex polypeptide (CCT-eta) is increased in fibrotic wound healing, and is essential for the accumulation of α-smooth muscle actin (α-SMA) in fibroblasts. The purpose of this study was to determine if CCT-eta is similarly implicated in the aberrant fibrosis seen in DC and to investigate the role of CCT-eta in the behavior of myo/fibroblasts in DC. Fibroblasts were obtained from DC-affected palmar fascia, from adjacent phenotypically normal palmar fascia in the same DC patients (PF), and from non-DC palmar fascial tissues in patients undergoing carpal tunnel (CT) release. Inherent contractility in these three populations was examined using fibroblast-populated collagen lattices (FPCLs) and by cell traction force microscopy. Expression of CCT-eta and α-SMA protein was determined by Western blot. The effect of CCT-eta inhibition on the contractility of DC cells was determined by deploying an siRNA versus CCT-eta. DC cells were significantly more contractile than both matching palmar fascial (PF) cells and CT cells in both assays, with PF cells demonstrating an intermediate contractility in the FPCL assay. Whereas α-SMA protein was significantly increased only in DC cells compared to PF and CT cells, CCT-eta protein was significantly increased in both PF and DC cells compared to CT cells. siRNA-mediated depletion of CCT-eta inhibited the accumulation of both CCT-eta and α-SMA protein in DC cells, and also significantly decreased the contractility of treated DC cells. These observations suggest that increased expression of CCT-eta appears to be a marker for latent and active disease in these patients and to be essential for the increased contractility exhibited by these fibroblasts.

Scarless integumentary wound healing in the mammalian fetus: molecular basis and therapeutic implications

Adult mammals respond to injury of their skin/integument by forming scar tissue. Scar is useful in rapidly sealing an injured area, but can also lead to significant morbidity. Mammals in fetal life retain the ability to heal integumentary wounds regeneratively, without scar. The critical molecular mechanisms governing this remarkable phenomenon have been a subject of great interest, in the hopes that these could be dissected and recapitulated in the healing adult wound, with the goal of inducing scarless healing in injured patients. Multiple lines of investigation spanning decades have implicated a number of factors in distinguishing scarless from fibrotic wound healing, including most prominently transforming growth factor-β and interleukin-10, among others. Therapeutic interventions to try to mitigate scarring in adult wounds have been developed out of these studies, and have reached the level of clinical trials in humans, although as yet no FDA-approved treatment exists. More recent expressomic studies have revealed many more genes that are differentially expressed in scarlessly healing fetal wounds compared with adult, and microRNAs have also been identified as participating in the fetal wound healing response. These represent an even greater range of potential therapeutics (or targets for therapy) to translate the promise of scarless fetal wound healing to the injured adult patient.

Transplanted fibroblasts prevents dysfunctional repair in a murine CXCR3-deficient scarring model

In skin, the regeneration of the ontogenically distinct mesenchymal and epithelial compartments must proceed in a coordinated manner orchestrated by extracellular signaling networks. We have recently found that the switch from regeneration to remodeling during repair is modulated by chemokines that bind CXCR3 receptor. If this signaling is disrupted wounds continue to be active, resulting in a chronic hypercellular and hypertrophic state characterized by an immature matrix composition. As healing is masterminded in large part by fibroblasts and their synthesis of the extracellular matrix, the question arose as to whether this ongoing scarring can be modulated by transplanted fibroblasts. We examined wounds in the CXCR3-/- mouse scarring model. These wounds exhibited a significant delay in healing in all areas compared to young and aged wild-type mice. Full-thickness wounds were transplanted with fibroblasts derived from newborn CXCR3-/- or wild-type mice. The transplanted fibroblasts were labeled with fluorescent dye (CM-DiI) and suspended in hyaluronic acid gel; by 30 days, these transplanted cells comprised some 30% of the dermal stromal cells regardless of the host or source of transplanted cells. Wild-type fibroblasts transplanted into CXCR3-/- mice wounds reversed the delay and dysfunction previously seen in CXCR3-/- wounds; this correction was not noted with transplanted CXCR3-/- fibroblasts. Additionally, transplant of CXCR3-/- cells into wounds in wild-type animals did not adversely affect those wounds. The transplanted fibroblasts exhibited strong survival and migration patterns and led to an increase in tensile strength. Expression of matrix proteins and collagen in CXCR3-/- wounds transplanted with wild-type fibroblasts resembled normal wild-type healing, and the wound matrix in wild-type mice transplanted with CXCR3-/- cells also presented a mature matrix. These suggest that the major determinant of healing versus scarring lies with the nature of the matrix. These findings have intriguing implications for rational cellular interventions aimed at promoting wound healing via cell therapy.

Chaperonin containing T-complex polypeptide (CCT) subunit expression in oral mucosal wounds and fibroblasts

Mucosal wound healing in adults has been reported to feature diminished scar formation compared to healing skin wounds. We sought to determine if the expression pattern of chaperonin containing T-complex polypeptide (CCT) subunits in mucosal wounds and fibroblasts is different from that observed in skin wounds and fibroblasts. We found that CCT-beta is the only subunit message to be reduced in wounded mucosa versus unwounded control, and this reduction was confirmed at the protein level. In contrast, mRNA levels of CCT-zeta, -delta, -eta, and -epsilon were significantly increased in mucosal wounds. The increase in CCT-eta was also confirmed at the protein level. Expression levels of CCT-alpha, -beta, -delta; -epsilon, and -theta mRNAs were significantly increased in adult mucosal fibroblasts in culture compared to skin-derived fibroblasts. Western blot analyses confirmed a modest increase in CCT-beta in adult mucosal fibroblasts relative to skin fibroblasts, but CCT-eta protein was unaffected. These differences may contribute to the reported difference in healing outcomes between these two tissue types.

Cellular and Molecular Characteristics of Scarless versus Fibrotic Wound Healing

The purpose of this paper is to compare and contrast the discrete biology differentiating fetal wound repair from its adult counterpart. Integumentary wound healing in mammalian fetuses is essentially different from wound healing in adult skin. Adult (postnatal) skin wound healing is a complex and well-orchestrated process spurred by attendant inflammation that leads to wound closure with scar formation. In contrast, fetal wound repair occurs with minimal inflammation, faster re-epithelialization, and without the accumulation of scar. Although research into scarless healing began decades ago, the critical molecular mechanisms driving the process of regenerative fetal healing remain uncertain. Understanding the molecular and cellular events during regenerative healing may provide clues that one day enable us to modulate adult wound healing and consequently reduce scarring.

Cloning and expression of rabbit CCT subunits eta and beta in healing cutaneous wounds

We have previously identified the CCT subunit eta as specifically reduced in healing fetal skin wounds by differential display, and observed that this reduction is not seen with any other CCT subunit. We now report the cloning and characterization of the cDNAs for rabbit CCT-eta and its closest evolutionary homolog, CCT-beta. Quantitative examination of CCT-eta and –beta message expression in healing fetal and adult wounds at 12 h post-injury confirms that CCT-eta mRNA is decreased in fetal wound tissues, but actually elevated in adult wound tissues. CCT-beta mRNA, in contrast, remains unchanged in both fetal and adult wound tissues. CCT-eta mRNA remains persistently elevated in healing adult wounds for 28 days following injury, whereas CCT-beta mRNA remains invariant throughout. CCT-eta protein is similarly increased, whereas CCT-beta protein remains unchanged. -smooth muscle actin (-SMA), a recognized substrate of CCT known to be important in integumentary wound healing, was also measured over the course of wound healing, and both mRNA and protein levels were elevated throughout the 28 days.

Chaperonin containing T-complex polypeptide subunit eta (CCT-eta) is a specific regulator of fibroblast motility and contractility

Integumentary wounds in mammalian fetuses heal without scar; this scarless wound healing is intrinsic to fetal tissues and is notable for absence of the contraction seen in postnatal (adult) wounds. The precise molecular signals determining the scarless phenotype remain unclear. We have previously reported that the eta subunit of the chaperonin containing T-complex polypeptide (CCT-eta) is specifically reduced in healing fetal wounds in a rabbit model. In this study, we examine the role of CCT-eta in fibroblast motility and contractility, properties essential to wound healing and scar formation. We demonstrate that CCT-eta (but not CCT-beta) is underexpressed in fetal fibroblasts compared to adult fibroblasts. An in vitro wound healing assay demonstrated that adult fibroblasts showed increased cell migration in response to epidermal growth factor (EGF) and platelet derived growth factor (PDGF) stimulation, whereas fetal fibroblasts were unresponsive. Downregulation of CCT-eta in adult fibroblasts with short inhibitory RNA (siRNA) reduced cellular motility, both basal and growth factor-induced; in contrast, siRNA against CCT-beta had no such effect. Adult fibroblasts were more inherently contractile than fetal fibroblasts by cellular traction force microscopy; this contractility was increased by treatment with EGF and PDGF. CCT-eta siRNA inhibited the PDGF-induction of adult fibroblast contractility, whereas CCT-beta siRNA had no such effect. In each of these instances, the effect of downregulating CCT-eta was to modulate the behavior of adult fibroblasts so as to more closely approximate the characteristics of fetal fibroblasts. We next examined the effect of CCT-eta modulation on alpha-smooth muscle actin (alpha-SMA) expression, a gene product well known to play a critical role in adult wound healing. Fetal fibroblasts were found to constitutively express less alpha-SMA than adult cells. Reduction of CCT-eta with siRNA had minimal effect on cellular beta-actin but markedly decreased alpha-SMA; in contrast, reduction of CCT-beta had minimal effect on either actin isoform. Direct inhibition of alpha-SMA with siRNA reduced both basal and growth factor-induced fibroblast motility. These results indicate that CCT-eta is a specific regulator of fibroblast motility and contractility and may be a key determinant of the scarless wound healing phenotype by means of its specific regulation of alpha-SMA expression.

Expression of receptor for activated C kinase 1 in healing skin and mucosal wounds

Postnatal (adult) mammalian wound healing results in the formation of scar, whereas fetal mammals are able to effect wound repair without scar. We have investigated the expression pattern of the receptor of activated C kinase 1 (RACK1), a pleiotropic G-protein-like molecule, in healing skin and mucosal wounds in a rabbit model after obtaining a full-length clone of the rabbit RACK1 cDNA. In both adult skin and mucosal wounds, RACK1 mRNA expression is decreased relative to unwounded controls. In contrast, in fetal skin wounds RACK1 expression is unaltered from fetal control. Fibroblasts derived from adult skin tissue express more RACK1 message than fetal skin fibroblasts. These observations suggest that RACK1 may play an important role in distinguishing scarless fetal wound healing from its scirrhous counterpart in adults.