Nestin expression is dynamically regulated in cardiomyocytes during embryogenesis

Nestin(+)- and Nestin(-)-Ventricular Cardiomyocytes Reenter the Cell Cycle In Vitro but Are Reciprocally Regulated in the Partial Apex-Resected 7-Day Neonatal Rat Heart

The 1-day-old neonatal rat heart contains two subpopulations of ventricular cardiomyocytes (NNVMs) that reenter the cell cycle in vitro and in vivo distinguished by the absence or de novo expression of the intermediate filament protein nestin. Furthermore, de novo nestin expression in NNVMs directly facilitated cell cycle reentry and elicited a morphological migratory phenotype. Previous studies have reported that ventricular cardiomyocytes failed to reenter the cell cycle following damage to the 7-day-old rodent heart. The present study tested the hypothesis that cell cycle reentry of one or both of the NNVM subpopulations of 7-day-old neonatal rat pups was compromised in vitro and/or in vivo following cardiac damage. Three-day treatment of 7-day-old NNVMs with the protein kinase C activator phorbol 12,13-dibutyrate and the serine/threonine p38α/β MAPK kinase inhibitor SB203580 facilitated cell cycle reentry into the S phase and G2-M phase of the cell cycle. Two distinct subpopulations of 7-day NNVMs reentered the cell cycle, and the predominant subpopulation was distinguished by de novo nestin expression. Three days following the sham-operation of 7-day-old neonatal rat hearts, cell cycle reentry was detected exclusively in NNVMs lacking nestin expression. Partial apex resection of 7-day-old neonatal rat hearts led to the de novo appearance of nestin(+)-NNVMs preferentially bordering the damaged region and a subpopulation reentered the S-phase and G2-M phase of the cell cycle in the absence of p38α/β MAPK inhibition. By contrast, cell cycle reentry of nestin(-)-NNVMs identified adjacent to the apex-resected region was significantly reduced. These data highlight the disparate in vivo regulation of the two subpopulations of NNVMs following damaged to the 7-day-old neonatal rat heart and reaffirm the premise that targeting the subpopulation of nestin(+)-ventricular cardiomyocytes identified in the ischemically damaged adult mammalian heart represents a plausible first step to initiate cell cycle reentry.

Histone H2A.Z Deacetylation and Dedifferentiation in Infarcted/Tip60-depleted Cardiomyocytes

Myocardial infarction (MI) results in the loss of billions of cardiomyocytes (CMs), resulting in cardiac dysfunction. To re-muscularize injured myocardium, new CMs must be generated via renewed proliferation of surviving CMs. Approaches to induce proliferation of CMs after injury have been insufficient. Toward this end we are targeting the acetyltransferase Tip60, encoded by the Kat5 gene, based on the rationale that its pleiotropic functions combine to block CM proliferation at multiple checkpoints. We previously demonstrated that genetic depletion of Tip60 in a mouse model after MI reduces scarring, retains cardiac function, and activates the CM cell-cycle, although it remains unclear whether this culminates in the generation of daughter CMs. In order for pre-existing CMs in the adult heart to undergo proliferation, it has become accepted that they must first dedifferentiate, a process highlighted by loss of maturity, epithelial to mesenchymal transitioning (EMT), and reversion from fatty acid oxidation to glycolytic metabolism, accompanied by softening of the myocardial extracellular matrix (ECM). Based on recently published findings that Tip60 induces and maintains the differentiated state of hematopoietic stem cells and neurons via site-specific acetylation of the histone variant H2A.Z, we assessed levels of acetylated H2A.Z and dedifferentiation markers after depleting Tip60 in CMs post-MI. We report that genetic depletion of Tip60 from CMs after MI results in the near obliteration of acetylated H2A.Z in CM nuclei, accompanied by the altered expression of genes indicative of EMT induction, ECM softening, decreased fatty acid oxidation, and depressed expression of genes that regulate the TCA cycle. In accord with the possibility that site-specific acetylation of H2A.Z maintains adult CMs in a mature state of differentiation, CUT&Tag revealed enrichment of H2A.ZacK4/K7 in genetic motifs and in GO terms respectively associated with CM transcription factor binding and muscle development/differentiation. Along with our previous findings, these results support the notion that Tip60 has multiple targets in CMs that combine to maintain the differentiated state and prevent proliferation.

Distribution, contribution and regulation of nestin+ cells

BACKGROUND

Nestin is an intermediate filament first reported in neuroepithelial stem cells. Nestin expression could be found in a variety of tissues throughout all systems of the body, especially during tissue development and tissue regeneration processes.

AIM OF REVIEW

This review aimed to summarize and discuss current studies on the distribution, contribution and regulation of nestin+ cells in different systems of the body, to discuss the feasibility ofusing nestin as a marker of multilineage stem/progenitor cells, and better understand the potential roles of nestin+ cells in tissue development, regeneration and pathological processes.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review highlights the potential of nestin as a marker of multilineage stem/progenitor cells, and as a key factor in tissue development and tissue regeneration. The article discussed the current findings, limitations, and potential clinical implications or applications of nestin+ cells. Additionally, it included the relationship of nestin+ cells to other cell populations. We propose potential future research directions to encourage further investigation in the field.

Rapamycin treatment unmasks a sex-specific pattern of scar expansion of the infarcted rat heart: The relationship between mTOR and KATP channel

Inhibition of the mammalian target of rapamycin (mTOR) with the macrolide rapamycin or pharmacological suppression of KATP channel opening translated to scar expansion of the myocardial infarcted (MI) adult female rodent heart. The present study tested the hypotheses that rapamycin-mediated scar expansion was sex-specific and that mTOR signaling directly influenced KATP channel subunit expression/activity. Scar size was significantly larger in post-MI male rats as compared to the previous data reported in post-MI female rats. The reported scar expansion of rapamycin-treated post-MI female rats was not observed following the administration of the macrolide to post-MI male rats. Protein levels of the KATP channel subunits Kir6.2 and SUR2A and phosphorylation of the serine2448 residue of mTOR were similar in the normal heart of adult male and female rats. By contrast, greater tuberin inactivation characterized by the increased phosphorylation of the threonine1462 residue and reduced raptor protein levels were identified in the normal heart of adult female rats. Rapamycin pretreatment of phorbol 12,13-dibutyrate (PDBu)-treated neonatal rat ventricular cardiomyocytes (NNVMs) suppressed hypertrophy, inhibited p70S6K phosphorylation, and attenuated SUR2A protein upregulation. In the presence of low ATP levels, KATP channel activity detected in untreated NNVMs was significantly attenuated in PDBu-induced hypertrophied NNVMs via a rapamycin-independent pathway. Thus, rapamycin administration to post-MI rats unmasked a sex-specific pattern of scar expansion and mTOR signaling in PDBu-induced hypertrophied NNVMs significantly increased SUR2A protein levels. However, the biological advantage associated with SUR2A protein upregulation was partially offset by an mTOR-independent pathway that attenuated KATP channel activity in PDBu-induced hypertrophied NNVMs.

Nestin identifies a subpopulation of rat ventricular fibroblasts and participates in cell migration

Fibroblast progenitor cells migrate to the endocardial region during cardiogenesis, and the migration of ventricular fibroblasts to the ischemically damaged region of the infarcted adult heart is a seminal event of reparative fibrosis. The intermediate filament protein nestin is implicated in cell migration and expression identified in a subpopulation of scar-derived myofibroblasts. The present study tested the hypothesis that fibroblast progenitor cells express nestin, and the intermediate filament protein drives the migratory phenotype of ventricular fibroblasts. Transcription factor 21 (Tcf21)- and Wilms tumor 1 (WT1)-fibroblast progenitor cells identified in the epicardial/endocardial regions of the E12.5- to E13.5-day embryonic mouse heart predominantly expressed nestin. Nuclear Tcf21/WT1 staining was identified in neonatal rat ventricular fibroblasts (NNVFbs), and a subpopulation coexpressed nestin. Nuclear Tcf21/WT1 expression persisted in adult rat ventricular fibroblasts, whereas nestin protein levels were downregulated. Nestin-expressing NNVFbs exhibited a unique phenotype as the subpopulation was refractory to cell cycle reentry in response to selective stimuli. Nestin(-)- and nestin(+)-scar-derived rat myofibroblasts plated in Matrigel unmasked a migratory phenotype characterized by the de novo formation of lumen-like structures. The elongated membrane projections emanating from scar myofibroblasts delineating the boundary of lumen-like structures expressed nestin. Lentiviral short-hairpin RNA (shRNA)-mediated nestin depletion inhibited the in vitro migratory response of NNVFbs as the wound radius was significantly larger compared with NNVFbs infected with the empty lentivirus. Thus, nestin represents a marker of embryonic Tcf21/WT1(+)-fibroblast progenitor cells. The neonatal rat heart contains a distinct subpopulation of nestin-immunoreactive Tcf21/WT1(+) fibroblasts refractory to cell cycle reentry, and the intermediate filament protein may preferentially facilitate ventricular fibroblast migration during physiological/pathological remodeling.NEW & NOTEWORTHY Tcf21/WT1(+)-fibroblast progenitor cells of the embryonic mouse heart predominantly express the intermediate filament protein nestin. A subpopulation of Tcf21/WT1(+)-neonatal rat ventricular fibroblasts express nestin and are refractory to selective stimuli influencing cell cycle reentry. Scar-derived myofibroblasts plated in Matrigel elicit the formation of lumen-like structures characterized by the appearance of nestin(+)-membrane projections. Lentiviral shRNA-mediated nestin depletion in a subpopulation of neonatal rat ventricular fibroblasts suppressed the migratory response following the in vitro scratch assay.

Distinct protein kinase C isoforms drive the cell cycle re-entry of two separate populations of neonatal rat ventricular cardiomyocytes

The present study tested the hypothesis that protein kinase C-α (PKC-α) recruitment in the presence of the p38α/β MAPK inhibitor SB203580 facilitated the appearance and cell cycle re-entry of nestin(+)-neonatal rat ventricular cardiomyocytes (NNVMs) and induced a transcript profile delineating a proliferative phenotype. Phorbol 12,13-dibutyrate (PDBu) treatment did not induce de novo nestin expression or increase the cell cycle re-entry of 1-day-old NNVMs but significantly increased runt-related transcription factor 1 (Runx1) and p16 cell cycle inhibitor (CDKN2a) mRNA levels and downregulated epithelial cell transforming 2 (ECT2) mRNA expression. SB203580 administration to PDBu-treated NNVMs induced de novo nestin expression, preferentially increased the density (normalized to 500 NNVMs) of nestin(+)-NNVMs that incorporated 5-bromo-2'-deoxyuridine (PDBu, 1.4 ± 3 vs. PDBu/SB203580, 128 ± 34; n = 5 independent litters), significantly inhibited CDKN2a and Runx1 mRNA upregulation and reversed ECT2 mRNA downregulation. PDBu treatment of NNVMs reduced PKC-α, protein kinase-δ (PKC-δ) and protein kinase-ε (PKC-ε) protein levels and GF109203X (conventional PKC isoform inhibitor) selectively attenuated PKC-α protein downregulation. GF109203X administration to PDBu/SB203580-treated NNVMs significantly reduced the density of nestin(+)-NNVMs that incorporated 5-bromo-2'-deoxyuridine (PDBu/SB203580/GF109203X, 40 ± 46; n = 5). Moreover, GF109203X/PDBu/SB203580 treatment unmasked the predominant appearance of a separate NNVM population that incorporated 5-bromo-2'-deoxyuridine (PDBu/SB203580/GF109203X, 192 ± 42; n = 5) delineated by the absence of de novo nestin expression. Sotrastaurin (conventional/novel PKC isoform inhibitor) administration to PDBu/SB203580-treated NNVMs significantly attenuated the density of nestin(+)-NNVMs (PDBu/SB203580/sotrastaurin, 8 ± 10; n = 4) and nestin(-)-NNVMs (PDBu/SB203580/sotrastaurin, 64 ± 30; n = 4) that incorporated 5-bromo-2'-deoxyuridine. These data reveal that the neonatal rat heart contains at least two separate populations of NNVMs that re-enter the cell cycle and the preferential appearance of nestin(+)- or nestin(-)-NNVMs is driven by distinct PKC isoforms in the presence of SB203580.NEW & NOTEWORTHY The appearance of nestin(+)-neonatal rat ventricular cardiomyocytes that re-entered the cell cycle following phorbol ester stimulation in the presence of p38α/β MAPK inhibitor SB203580 was associated with the inhibition of Runx1 and CDKN2a mRNA upregulation. PKC-α selectively induced the cell cycle re-entry of nestin(+)-neonatal rat ventricular cardiomyocytes. Pharmacological inhibition of PKC-α with concomitant p38α/β MAPK suppression unmasked the cell cycle re-entry of a second population of neonatal rat ventricular cardiomyocytes in the absence of nestin expression.

The ascending aorta of male hypertensive bicuspid aortic valve patients preferentially associated with a cellular aneurysmal phenotype

Male sex and hypertension represent risk factors in the progression of an aortic aneurysm. The present study examined the morphological/cellular phenotype of the ascending aorta (AA) of male and female patients diagnosed with a bicuspid aortic valve (BAV) to test the hypothesis that hypertension-induced remodeling of male BAV patients preferentially recapitulated the expression of a panel of proteins favoring aneurysm formation. The diameter of the AA of hypertensive male (35 ± 6 mm) and female (39 ± 5 mm) BAV patients was comparable to normotensive patients reflecting an early phase of vessel expansion. Morphological/structural remodeling of the medial region of the AA of male normotensive and hypertensive BAV patients were comparable. Protein levels of non-muscle myosin IIB, the cell cycle inhibitor p27kip1, tumor suppressor p53 and matrix metalloproteinase-2 and -9 were significantly upregulated in the AA of male hypertensive BAV patients. In female hypertensive BAV patients, collagen content was significantly increased whereas elastin content and medial width of the AA were similar to normotensive BAV patients. In the AA of female hypertensive BAV patients, matrix metalloproteinase-9 and p27kip1 protein levels were unchanged whereas p53 and matrix metalloproteinase-2 protein expression was significantly reduced. Nestin protein levels were diminished in the AA of male and female hypertensive BAV patients. Thus, sexual dimorphic remodeling of the AA was prevalent in hypertensive BAV patients. Moreover, during the early phase of vessel expansion, the AA of male hypertensive BAV patients was preferentially associated with the upregulation of a panel of proteins linked to progressive dilatation and potential aneurysm formation.

Sympathetic Stimulation Upregulates the Ca2+ Channel Subunit, CaVα2δ1, via the β1 and ERK 1/2 Pathway in Neonatal Ventricular Cardiomyocytes

Intracellular Ca2+ overload secondary to chronic hemodynamic stimuli promotes the recruitment of Ca2+-dependent signaling implicated in cardiomyocyte hypertrophy. The present study tested the hypothesis that sympathetic-mediated hypertrophy of neonatal rat ventricular cardiomyocytes (NRVMs) translated to an increase in calcium influx secondary to the upregulation of CaV1.2 channel subunits. Confocal imaging of norepinephrine (NE)-treated NRVMs revealed a hypertrophic response compared to untreated NRVMs. L-type CaV1.2 peak current density was increased 4-fold following a 24-h stimulation with NE. NE-treated NRVMs exhibited a significant upregulation of CaVα2δ1 and CaVβ3 protein levels without significant changes of CaVα1C and CaVβ2 protein levels. Pre-treatment with the β1-blocker metoprolol failed to inhibit hypertrophy or CaVβ3 upregulation whereas CaVα2δ1 protein levels were significantly reduced. NE promoted the phosphorylation of ERK 1/2, and the response was attenuated by the β1-blocker. U0126 pre-treatment suppressed NE-induced ERK1/2 phosphorylation but failed to attenuate hypertrophy. U0126 inhibition of ERK1/2 phosphorylation prevented NE-mediated upregulation of CaVα2δ1, whereas CaVβ3 protein levels remained elevated. Thus, β1-adrenergic receptor-mediated recruitment of the ERK1/2 plays a seminal role in the upregulation of CaVα2δ1 in NRVMs independent of the concomitant hypertrophic response. However, the upregulation of CaVβ3 protein levels may be directly dependent on the hypertrophic response of NRVMs.

The Role of Photoactivated and Non-Photoactivated Verteporfin on Tumor

Verteporfin (VP) has long been clinically used to treat age-related macular degeneration (AMD) through photodynamic therapy (PDT). Recent studies have reported a significant anti-tumor effect of VP as well. Yes-associated protein (YAP) is a pro-tumorigenic factor that is aberrantly expressed in various cancers and is a central effector of the Hippo signaling pathway that regulates organ size and tumorigenesis. VP can inhibit YAP without photoactivation, along with suppressing autophagy, and downregulating germinal center kinase-like kinase (GLK) and STE20/SPS1-related proline/alanine-rich kinase (SPAK). In addition, VP can induce mitochondrial damage and increase the production of reactive oxygen species (ROS) upon photoactivation, and is an effective photosensitizer (PS) in anti-tumor PDT. We have reviewed the direct and adjuvant therapeutic action of VP as a PS, and its YAP/TEA domain (TEAD)-dependent and independent pharmacological effects in the absence of light activation against cancer cells and solid tumors. Based on the present evidence, VP may be repositioned as a promising anti-cancer chemotherapeutic and adjuvant drug.

ERBB2 drives YAP activation and EMT-like processes during cardiac regeneration

Cardiomyocyte loss after injury results in adverse remodelling and fibrosis, inevitably leading to heart failure. The ERBB2-Neuregulin and Hippo-YAP signalling pathways are key mediators of heart regeneration, yet the crosstalk between them is unclear. We demonstrate that transient overexpression of activated ERBB2 in cardiomyocytes (OE CMs) promotes cardiac regeneration in a heart failure model. OE CMs present an epithelial-mesenchymal transition (EMT)-like regenerative response manifested by cytoskeletal remodelling, junction dissolution, migration and extracellular matrix turnover. We identified YAP as a critical mediator of ERBB2 signalling. In OE CMs, YAP interacts with nuclear-envelope and cytoskeletal components, reflecting an altered mechanical state elicited by ERBB2. We identified two YAP-activating phosphorylations on S352 and S274 in OE CMs, which peak during metaphase, that are ERK dependent and Hippo independent. Viral overexpression of YAP phospho-mutants dampened the proliferative competence of OE CMs. Together, we reveal a potent ERBB2-mediated YAP mechanotransduction signalling, involving EMT-like characteristics, resulting in robust heart regeneration.

Filamentous nestin and nonmuscle myosin IIB are associated with a migratory phenotype in neonatal rat cardiomyocytes

Cardiomyocyte migration represents a requisite event of cardiogenesis and the regenerative response of the injured adult zebrafish and neonatal rodent heart. The present study tested the hypothesis that the appearance of the intermediate filament protein nestin in neonatal rat ventricular cardiomyocytes (NNVMs) was associated in part with the acquisition of a migratory phenotype. The cotreatment of NNVMs with phorbol 12,13-dibutyrate (PDBu) and the p38α/β mitogen-activated protein kinase inhibitor SB203580 led to the de novo synthesis of nestin. The intermediate filament protein was subsequently reorganized into a filamentous pattern and redistributed to the leading edge of elongated membrane protrusions translating to significant lengthening of NNVMs. PDBu/SB203580 treatment concomitantly promoted the reorganization of nonmuscle myosin IIB (NMIIB) located predominantly at the periphery of the plasma membrane of NNVMs to a filamentous phenotype extending to the leading edge of elongated membrane protrusions. Coimmunoprecipitation assay revealed a physical interaction between NMIIB and nestin after PDBu/SB203580 treatment of NNVMs. In wild-type and heterozygous NMIIB embryonic hearts at E11.5-E14.5 days, nestin immunoreactivity was identified in a subpopulation of cardiomyocytes elongating perpendicular to the compact myocardium, at the leading edge of nascent trabeculae and during thickening of the compact myocardium. In mutant embryonic hearts lacking NMIIB protein expression, trabeculae formation was reduced, the compact myocardium significantly thinner and nestin immunoreactivity undetectable in cardiomyocytes at E14.5 days. These data suggest that NMIIB and nestin may act in a coordinated fashion to facilitate the acquisition of a migratory phenotype in neonatal and embryonic cardiomyocytes.

Molecular Mechanism of Hippo-YAP1/TAZ Pathway in Heart Development, Disease, and Regeneration

The Hippo-YAP1/TAZ pathway is a highly conserved central mechanism that controls organ size through the regulation of cell proliferation and other physical attributes of cells. The transcriptional factors Yes-associated protein 1 (YAP1) and PDZ-binding motif (TAZ) act as downstream effectors of the Hippo pathway, and their subcellular location and transcriptional activities are affected by multiple post-translational modifications (PTMs). Studies have conclusively demonstrated a pivotal role of the Hippo-YAP1/TAZ pathway in cardiac development, disease, and regeneration. Targeted therapeutics for the YAP1/TAZ could be an effective treatment option for cardiac regeneration and disease. This review article provides an overview of the Hippo-YAP1/TAZ pathway and the increasing impact of PTMs in fine-tuning YAP1/TAZ activation; in addition, we discuss the potential contributions of the Hippo-YAP1/TAZ pathway in cardiac development, disease, and regeneration.

p38α MAPK inhibition translates to cell cycle re-entry of neonatal rat ventricular cardiomyocytes and de novo nestin expression in response to thrombin and after apex resection

The present study tested the hypothesis that p38α MAPK inhibition leads to cell cycle re-entry of neonatal ventricular cardiomyocytes (NNVMs) and de novo nestin expression in response to thrombin and after apex resection of the neonatal rat heart. Thrombin (1 U/ml) treatment of 1-day old NNVMs did not induce cell cycle re-entry or nestin expression. Acute exposure of NNVMs to thrombin increased p38α MAPK and HSP27 phosphorylation and p38α/β MAPK inhibitor SB203580 abrogated HSP27 phosphorylation. Thrombin and SB203580 co-treatment of NNVMs led to bromodeoxyuridine incorporation and nestin expression. SB203580 (5 mg/kg) administration immediately after apex resection of 1-day old neonatal rat hearts and continued for two additional days shortened the fibrin clot length sealing the exposed left ventricular chamber. SB203580-treatment increased the density of troponin-T(+)-NNVMs that incorporated bromodeoxyuridine and expressed nuclear phosphohistone-3. Nestin(+)-NNVMs were selectively detected at the border of the fibrin clot and SB203580 potentiated the density that re-entered the cell cycle. These data suggest that the greater density of ventricular cardiomyocytes and nestin(+)-ventricular cardiomyocytes that re-entered the cell cycle after SB203580 treatment of the apex-resected neonatal rat heart during the acute phase of fibrin clot formation may be attributed in part to inhibition of thrombin-mediated p38α MAPK signalling.

A systems-approach reveals human nestin is an endothelial-enriched, angiogenesis-independent intermediate filament protein

The intermediate filament protein nestin is expressed during embryonic development, but considered largely restricted to areas of regeneration in the adult. Here, we perform a body-wide transcriptome and protein-profiling analysis to reveal that nestin is constitutively, and highly-selectively, expressed in adult human endothelial cells (EC), independent of proliferative status. Correspondingly, we demonstrate that it is not a marker for tumour EC in multiple malignancy types. Imaging of EC from different vascular beds reveals nestin subcellular distribution is shear-modulated. siRNA inhibition of nestin increases EC proliferation, and nestin expression is reduced in atherosclerotic plaque neovessels. eQTL analysis reveals an association between SNPs linked to cardiovascular disease and reduced aortic EC nestin mRNA expression. Our study challenges the dogma that nestin is a marker of proliferation, and provides insight into its regulation and function in EC. Furthermore, our systems-based approach can be applied to investigate body-wide expression profiles of any candidate protein.

miR-145 protects the function of neuronal stem cells through targeting MAPK pathway in the treatment of cerebral ischemic stroke rat

This study is designed to investigate the function of the miR-145 in the protection of neural stem cells (NSCs) through targeting mitogen-activated protein kinase (MAPK) pathway in the treatment of cerebral ischemic stroke rat. In our study, rat NSCs were selected and cultured in complete medium. The light microscopy was used to observe the morphology of NSCs at different times. The quantitative reverse transcriptase real-time polymerase chain reaction (qRT-PCR) was used to detect the miR-145 and other related mRNAs of the MARK pathway. The Western blotting was used to detect the activation of MAPK pathway and neuronal specific markers. The Immunofluorescence was used to detect the expression of the neuron-specific enolase. And the cell viability was detected by Cell Counting Kit (CCK)-8 assay. The flow cytometry was used to test the cell cycle and apoptosis. The ischemic stroke rat models were established and neural stem cell transplantation was performed. The neurological function score, balance beam experiment, and cortical Nissl staining were used to evaluate the postoperative neurological function in rats. The expression of miR-145, extracellular signal-regulated kinase (ERK), and p38 mRNA in rat NSCs increased in a time-dependent manner. Compared with the Blank group, the over-expression of miR-145 promoted the expression of related mRNA and protein of the MAPK pathway in NSCs, while the decreased expression of miR-145 suppressed the MAPK Pathways. Compared with the Blank group, over-expression of miR-145 in NSCs promoted the up-regulation of Cyclin D1, Nestin, neuron-specific enolase (NSE), and Glial fibrillary acidic protein (GFAP) proteins, enhanced the activity of NSCs, and promoted cell proliferation and differentiation, while inhibited the cell apoptosis and the Cleaved-caspase 3 expression. After treatment of NSCs in the SB203580 group, the Nestin, NSE, and GFAP were decreased; cell viability, proliferation and differentiation were inhibited, while Cleaved-caspase 3 protein and cell apoptosis rate increased. The results of animal experiments showed that compared with the Blank group, the walking ability and neurological impairment recovered rapidly in the rats after transplantation of NSCs with over-expression of miR-145, and more neurons were generated in the cortex. After the transplantation of SB203580-treated NSCs, the walking ability and neurological impairment of the rats were slower and the cortical neurons were less. We conclude that miR-145 protects the function of neuronal stem cells through targeting MAPK pathway in the treatment of cerebral ischemic stroke rat.

The Biological Role of Nestin(+)-Cells in Physiological and Pathological Cardiovascular Remodeling

The intermediate filament protein nestin was identified in diverse populations of cells implicated in cardiovascular remodeling. Cardiac resident neural progenitor/stem cells constitutively express nestin and following an ischemic insult migrate to the infarct region and participate in angiogenesis and neurogenesis. A modest number of normal adult ventricular fibroblasts express nestin and the intermediate filament protein is upregulated during the progression of reparative and reactive fibrosis. Nestin depletion attenuates cell cycle re-entry suggesting that increased expression of the intermediate filament protein in ventricular fibroblasts may represent an activated phenotype accelerating the biological impact during fibrosis. Nestin immunoreactivity is absent in normal adult rodent ventricular cardiomyocytes. Following ischemic damage, the intermediate filament protein is induced in a modest population of pre-existing adult ventricular cardiomyocytes bordering the peri-infarct/infarct region and nestin⁽⁺⁾-ventricular cardiomyocytes were identified in the infarcted human heart. The appearance of nestin⁽⁺⁾-ventricular cardiomyocytes post-myocardial infarction (MI) recapitulates an embryonic phenotype and depletion of the intermediate filament protein inhibits cell cycle re-entry. Recruitment of the serine/threonine kinase p38 MAPK secondary to an overt inflammatory response after an ischemic insult may represent a seminal event limiting the appearance of nestin⁽⁺⁾-ventricular cardiomyocytes and concomitantly suppressing cell cycle re-entry. Endothelial and vascular smooth muscle cells (VSMCs) express nestin and upregulation of the intermediate filament protein may directly contribute to vascular remodeling. This review will highlight the biological role of nestin⁽⁺⁾-cells during physiological and pathological remodeling of the heart and vasculature and discuss the phenotypic advantage attributed to the intermediate filament protein.