Periostin splice variants affect craniofacial growth by influencing chondrocyte hypertrophy.

INTRODUCTION: Periostin, an extracellular matrix protein, plays an important role in osteogenesis and is also known to activate several signals that contribute to chondrogenesis. The absence of periostin in periostin knockout mice leads to several disorders such as craniosynostosis and periostitis. There are several splice variants with different roles in heart disease and myocardial infarction. However, little is known about each variant's role in chondrogenesis, followed by bone formation. Therefore, the aim of this study is to investigate the role of several variants in chondrogenesis differentiation and bone formation in the craniofacial region. Periostin splice variants included a full-length variant (Control), a variant lacking exon 17 (ΔEx17), a variant lacking exon 21 (ΔEx21), and another variant lacking both exon 17 and 21 ***(ΔEx17&21). MATERIALS AND METHODS: We used C56BL6/N mice (n = 6) for the wild type (Control)*** and the three variant type mice (n = 6 each) to identify the effect of each variant morphologically and histologically. Micro-computed tomography demonstrated a smaller craniofacial skeleton in ΔEx17s, ΔEx21s, and ΔEx17&21s compared to Controls, especially the mandibular bone. We, thus, focused on the mandibular condyle. RESULTS: The most distinctive histological observation was that each defected mouse appeared to have more hypertrophic chondrocytes than Controls. Real-time PCR demonstrated the differences among the group. Moreover, the lack of exon 17 or exon 21 in periostin leads to inadequate chondrocyte differentiation and presents in a diminutive craniofacial skeleton. DISCUSSION: Therefore, these findings suggested that each variant has a significant role in chondrocyte hypertrophy, leading to suppression of bone formation.

Induction of Angiogenesis by a Type III Phosphodiesterase Inhibitor, Cilostazol, Through Activation of Peroxisome Proliferator-Activated Receptor-γ and cAMP Pathways in Vascular Cells.

OBJECTIVE: Peripheral arterial disease is highly prevalent in the elderly and in the subjects with cardiovascular risk factors such as diabetes. Approximately 2% to 4% of those affected with peripheral arterial disease commonly complain of intermittent claudication. Cilostazol, a type III phosphodiesterase inhibitor, is the only Food and Drug Administration-approved drug for the treatment of intermittent claudication. Cilostazol has been shown to be beneficial for the improvement of pain-free walking distance in patients with intermittent claudication in a series of randomized clinical trials. However, the underlying mechanism how cilostazol improved intermittent claudication symptoms is still unclear. APPROACH AND RESULTS: In this study, the effect of cilostazol on ischemic leg was investigated in mouse ischemic hindlimb model. Administration of cilostazol significantly increased the expression of hepatocyte growth factor (HGF), vascular endothelial growth factor, angiopoietin-1, and peroxisome proliferator-activated receptor-γ in vasculature. The capillary density in ischemic leg was also significantly increased in cilostazol treatment group when compared with control and aspirin treatment group. However, an increase in capillary density and the expression of growth factors was almost completely abolished by coadministration of HGF-neutralizing antibody, suggesting that cilostazol enhanced angiogenesis mainly through HGF. In vitro experiment revealed that cilostazol treatment increased HGF production in vascular smooth muscle cells via 2 major pathways: peroxisome proliferator-activated receptor-γ and cAMP pathways. CONCLUSIONS: Our data suggest that the favorable effects of cilostazol on ischemic leg might be through the angiogenesis through the induction of HGF via peroxisome proliferator-activated receptor-γ and cAMP pathways.

Different roles played by periostin splice variants in retinal neovascularization.

Retinal neovascularization (NV) due to retinal ischemia is one of the major causes of vision reduction in patients with different types of retinal diseases although anti-vascular endothelial growth factor (anti-VEGF) therapy can partially reduce the size of the retinal NV. We recently reported that periostin plays an important role in the development of NV and the formation of preretinal fibrovascular membranes, but the role of the splice variants of periostin on retinal NV has not been determined. We examined the expressions of periostin splice variants in the ischemic retinas of a mouse model of oxygen-induced retinal NV. We also studied the function of periostin splice variants on retinal NV using periostin knock out mice, and the effects of anti-periostin antibodies on retinal NV. Our results showed that the expressions of the periostin splice variants were increased in ischemic retinas. The degree of increase of periostin lacking exon 17 was the highest among the periostin splice variants examined. Both genetic ablation of periostin exons 17 and 21 and antibodies for periostin exons 17 and 21 affected preretinal pathological NV. Inhibition of exon 17 of periostin had the greatest effect in reducing preretinal pathological NV. These findings suggest a causal link between periostin splice variants and retinal NV, and an intravitreal injection of antibody for exon 17 and exon 21 of periostin should be considered to inhibit preretinal pathological NV.

Expression and pathological effects of periostin in human osteoarthritis cartilage.

BACKGROUND: Osteoarthritis (OA) is one of the most common joint diseases in elderly people, however, the underlying mechanism of OA pathogenesis is not completely clear. Periostin, the extracellular protein, has been shown by cDNA array analysis to be highly expressed in OA, but its function is not fully understood. The purpose of this study was to examine the expression and function of periostin in human OA. METHODS: Human cartilage and synovia samples were used for the analysis of periostin expression and function. The human cartilage samples were obtained from the knees of patients undergoing total knee arthroplasty as OA samples and from the femoral bone head of patients with femoral neck fracture as control samples. Quantitative RT-PCR, ELISA, and immunohistochemistry were used for analysis of periostin expression in cartilage and synovia. Human primary chondrocytes isolated from control cartilage were stimulated by periostin, and the alteration of OA related gene expression was examined using quantitative RT-PCR. Immunocytochemistry of p65 was performed for the analysis of nuclear factor kappa B (NFκB) activation. RESULTS: The periostin mRNA was significantly higher in OA cartilage than in control cartilage. Immunohistochemical analysis of periostin showed that the main positive signal was localized in chondrocytes and their periphery matrix near the erosive area, with less immunoreactivity in deeper zones. There was positive correlation between Mankin score and periostin immunoreactivity. The periostin expression was also detected in the fibrotic cartilage and tissue of subchondral bone. In cultured human chondrocytes, periostin induced the expression of interleukin (IL)-6, IL-8, matrix metalloproteinase (MMP)-1, MMP-3, MMP-13, and nitric oxide synthase-2 (NOS2) in a dose- and time-dependent manner. The activation of NFκB signaling was recognized by the nuclear translocation of p65. Periostin-induced upregulation of these genes was suppressed by NFκB inactivation in chondrocytes. CONCLUSION: Periostin was upregulated in OA cartilage, and it may amplify inflammatory events and accelerate OA pathology.

Docking protein Gab1 is an essential component of postnatal angiogenesis after ischemia via HGF/c-met signaling.

RATIONALE: Grb2-associated binder (Gab) docking proteins, consisting of Gab1, Gab2, and Gab3, have crucial roles in growth factor-dependent signaling. Various proangiogenic growth factors regulate angiogenesis and endothelial function. However, the roles of Gab proteins in angiogenesis remain elusive. OBJECTIVE: To elucidate the role of Gab proteins in postnatal angiogenesis. METHODS AND RESULTS: Endothelium-specific Gab1 knockout (Gab1ECKO) mice were viable and showed no obvious defects in vascular development. Therefore, we analyzed a hindlimb ischemia (HLI) model of control, Gab1ECKO, or conventional Gab2 knockout (Gab2KO) mice. Intriguingly, impaired blood flow recovery and necrosis in the operated limb was observed in all of Gab1ECKO, but not in control or Gab2KO mice. Among several proangiogenic growth factors, hepatocyte growth factor (HGF) induced the most prominent tyrosine phosphorylation of Gab1 and subsequent complex formation of Gab1 with SHP2 (Src homology-2-containing protein tyrosine phosphatase 2) and phosphatidylinositol 3-kinase subunit p85 in human endothelial cells (ECs). Gab1-SHP2 complex was required for HGF-induced migration and proliferation of ECs via extracellular signal-regulated kinase (ERK)1/2 pathway and for HGF-induced stabilization of ECs via ERK5. In contrast, Gab1-p85 complex regulated activation of AKT and contributed partially to migration of ECs after HGF stimulation. Microarray analysis demonstrated that HGF upregulated angiogenesis-related genes such as KLF2 (Krüppel-like factor 2) and Egr1 (early growth response 1) via Gab1-SHP2 complex in human ECs. In Gab1ECKO mice, gene transfer of vascular endothelial growth factor, but not HGF, improved blood flow recovery and ameliorated limb necrosis after HLI. CONCLUSION: Gab1 is essential for postnatal angiogenesis after ischemia via HGF/c-Met signaling.

Hepatocyte growth factor inhibits lipopolysaccharide-induced oxidative stress via epithelial growth factor receptor degradation.

OBJECTIVE: Lipopolysaccharide (LPS) triggers sepsis and systemic inflammatory response syndrome, which results in multiple organ failure. Our recent reports demonstrated that hepatocyte growth factor (HGF) attenuated angiotensin II-induced oxidative stress via epithelial growth factor receptor (EGFR) degradation in vascular smooth muscle cells. Here, we examined whether HGF can protect against systemic inflammatory response syndrome induced by LPS and investigated the mechanism. METHODS AND RESULTS: HGF inhibited the increase in the expression of vascular cell adhesion molecule-1 and EGFR by LPS in vitro. HGF inhibited colocalization of EGFR and Src homology domain 2-containing inositol 5'-phosphatase 2. Furthermore, HGF inhibited reactive oxygen species production. We also injected LPS into HGF transgenic mice with increased HGF serum concentration and their littermates. HGF transgenic mice reduced LPS-induced vascular cell adhesion molecule-1 and reactive oxygen species compared with control, accompanied by significant EGFR degradation. Furthermore, HGF transgenic mice significantly improved survival in the LPS injection model. CONCLUSIONS: The present study revealed inhibition of LPS-induced vascular cell adhesion molecule-1 expression by HGF via the degradation of EGFR. We demonstrated that HGF regulated Src homology domain 2-containing inositol 5'-phosphatase 2 recruitment to EGFR and inhibited LPS-induced inflammation via EGFR degradation. This effect of HGF may be useful for the treatment of inflammatory disease.

Role of central nervous system periostin in cerebral ischemia.

BACKGROUND AND PURPOSE: Although periostin, an extracellular matrix glycoprotein, plays pivotal roles in survival, migration, and regeneration in various cells, its expression and function in the brain are still unknown. Here, we investigated the expression and role of periostin in the ischemic brain. METHODS: Expression of full-length periostin (periostin 1 [Pn1]) and its splicing variant lacking exon 17 (periostin 2 [Pn2]) was examined by real-time reverse transcription polymerase chain reaction (RT-PCR), Western blotting, and immunohistochemical staining in male C57BL6/J mice. The actions of periostin were examined in adult primary neuronal culture and in a transient middle cerebral artery occlusion (tMCAo) model. RESULTS: Expression of Pn2, but not of Pn1, mRNA was markedly changed after tMCAo. Pn2 mRNA was decreased in the ischemic core at 3 hours after ischemia. At 24 hours, Pn2 mRNA was significantly increased in both the peri-ischemic and ischemic regions. Periostin was mainly observed in neurons in normal brain. However, neuronal expression of periostin was decreased temporarily in the ischemic region, but increased in astrocytes and around endothelial cells at 24 hours after tMCAo. Of importance, intracerebroventricular injection of Pn2 resulted in a significant reduction in infarct volume at 24 hours after tMCAo associated with phosphorylation of Akt. Also, the Pn2-treated mice survived longer until 1 week after tMCAo. Pn2 significantly inhibited neuronal death under hypoxia and stimulated neurite outgrowth. CONCLUSIONS: Here, we demonstrated that periostin was expressed in the brain, and exogenous Pn2 exhibited neuroprotective effects and accelerated neurite outgrowth. Additional studies on periostin may provide new insights into the treatment of ischemic stroke.

Inhibition of Lp(a)-induced functional impairment of endothelial cells and endothelial progenitor cells by hepatocyte growth factor.

BACKGROUND: Lipoprotein (a) (Lp(a)) is one of the risk factors for peripheral artery disease (PAD). Our previous report demonstrated that hepatocyte growth factor (HGF) gene therapy attenuated the impairment of collateral formation in Lp(a) transgenic mice. Since risk factors for atherosclerosis accelerate endothelial senescence and impair angiogenesis, we examined the role of Lp(a) in dysfunction and senescence of endothelial progenitor cells (EPC) and endothelial cells. METHODS: In vitro and in vivo incorporation assays were performed using ex-vivo expanded DiI-labeled human EPC. Senescence of cultured endothelial cells, production of oxidative stress and angiogenesis function were evaluated by SA-ß-galactosidase staining, dihydroethidium (DHE) staining and Matrigel assay, respectively. RESULTS: EPC transplantation significantly stimulated recovery of ischemic limb perfusion, while EPC pre-treated with Lp(a) did not increase ischemic limb perfusion. Impairment of angiogenesis by EPC with Lp(a) was associated with a significant decrease in CD31-positive capillaries and DiI-labeled EPC. Importantly, Lp(a) significantly accelerated the onset of senescence and production of reactive oxygen species (ROS) in human aortic endothelial cells, accompanied by a significant increase in the protein expression of p53 and p21. On the other hand, HGF significantly attenuated EPC dysfunction, senescence, ROS production, and p53 and p21 expression induced by Lp(a). CONCLUSION: Lp(a) might affect atherosclerosis via acceleration of senescence, ROS production, and functional impairment of the endothelial cell lineage. HGF might have inhibitory effects on these atherogenic actions of Lp(a).

Phase I/IIa clinical trial of therapeutic angiogenesis using hepatocyte growth factor gene transfer to treat critical limb ischemia.

OBJECTIVE: To evaluate the safety and feasibility of intramuscular gene transfer using naked plasmid DNA-encoding hepatocyte growth factor (HGF) and to assess its potential therapeutic benefit in patients with critical limb ischemia. METHODS AND RESULTS: Gene transfer was performed in 22 patients with critical limb ischemia by intramuscular injection of HGF plasmid, either 2 or 4 mg, 2 times. Safety, ankle-brachial index, resting pain on a 10-cm visual analog scale, wound healing, and walking distance were evaluated before treatment and at 2 months after injection. No serious adverse event caused by gene transfer was detected over a follow-up of 6 months. Of particular importance, no peripheral edema, in contrast to that seen after treatment with vascular endothelial growth factor, was observed. In addition, the systemic HGF protein level did not increase during the study. At 2 months after gene transfer, the mean ± SD ankle-brachial index increased from 0.46 ± 0.08 to 0.59 ± 0.13 (P<0.001), the mean ± SD size of the largest ischemic ulcers decreased from 3.08 ± 1.54 to 2.32 ± 1.88 cm (P=0.007), and the mean ± SD visual analog scale score decreased from 5.92 ± 1.67 to 3.04 ± 2.50 cm (P=0.001). An increase in ankle-brachial index by >0.1, a reduction in ulcer size by >25%, and a reduction in visual analog scale score by >2 cm at 2 months after gene transfer were observed in 11 (64.7%) of 17 limbs, 18 (72%) of 25 ulcers, and 8 (61.5%) of 13 limbs, respectively. CONCLUSIONS: Intramuscular injection of naked HGF plasmid is safe and feasible and can achieve successful improvement of ischemic limbs as sole therapy.

Lower body mass index potentiates the association between skipping breakfast and prevalence of proteinuria.

Background: Proteinuria is an important predictor of cardiovascular disease and mortality. Several studies reported the association between skipping breakfast and the prevalence of proteinuria. Furthermore, skipping breakfast was associated with an increased risk of obesity. Although proteinuria is highly prevalent in obese individuals, the association between the prevalence of proteinuria and low body mass index (BMI) was reported in a previous cross-sectional study in asymptomatic individuals without known kidney diseases. The aim of this cross-sectional study was to assess the clinical impact of BMI on the association between skipping breakfast and the prevalence of proteinuria in normal renal function subjects. Methods: The present study included 26,888 subjects (15,875 males and 11,013 females) with an estimated glomerular filtration rate ≥60 ml/min/1.73 m2 and no history of kidney disease who underwent a health checkup in Sumitomo Hospital. The association between skipping breakfast and the prevalence of proteinuria (defined as dipstick proteinuria of ≥1+) was assessed using logistic regression models adjusted for clinically relevant factors. Results: Skipping breakfast was reported in 3,306 males (20.8%) and 1,514 females (13.8%). Multivariable adjusted logistic regression models showed that skipping breakfast was significantly associated with the prevalence of proteinuria above 1+. This association was evident in lower BMI subjects, even after adjusting for clinically relevant factors (adjusted odds ratios of males and females were 1.67 [1.17-2.38] and 1.92 [1.31-2.82], respectively), whereas this association was not evident in higher BMI subjects. Conclusion: Lower BMI subjects with proteinuria might need to be careful about skipping breakfast.

Blocking Periostin Prevented Development of Inflammation in Rhabdomyolysis-Induced Acute Kidney Injury Mice Model.

BACKGROUND: Rhabdomyolysis is the collapse of damaged skeletal muscle and the leakage of muscle-cell contents, such as electrolytes, myoglobin, and other sarcoplasmic proteins, into the circulation. The glomeruli filtered these products, leading to acute kidney injury (AKI) through several mechanisms, such as intratubular obstruction secondary to protein precipitation. The prognosis is highly mutable and depends on the underlying complications and etiologies. New therapeutic plans to reduce AKI are now needed. Up to now, several cellular pathways, with the nuclear factor kappa beta (NF-kB), as well as the proinflammatory effects on epithelial and tubular epithelial cells, have been recognized as the major pathway for the initiation of the matrix-producing cells in AKI. Recently, it has been mentioned that periostin (POSTN), an extracellular matrix protein, is involved in the development of inflammation through the modulation of the NF-kB pathway. However, how POSTN develops the inflammation protection in AKI by rhabdomyolysis is uncertain. This study aimed to investigate the role of POSTN in a rhabdomyolysis mice model of AKI induced by an intramuscular injection of 50% glycerol. METHODS: In vivo, we performed an intramuscular injection of 50% glycerol (5 mg/kg body weight) to make rhabdomyolysis-induced AKI. We examined the expression level of POSTN through the progression of AKI after glycerol intramuscular injection for C57BL/6J wildtype (WT) mice. We sacrificed mice at 72 h after glycerol injection. We made periostin-null mice to examine the role of POSTN in acute renal failure. The role of periostin was further examined through in vitro methods. The development of renal inflammation is linked with the NF-kB pathway. To examine the POSTN function, we administrated hemin (100 µM) on NIH-3T3 fibroblast cells, and the following signaling pathways were examined. RESULTS: The expression of periostin was highly increased, peaking at about 72 h after glycerol injection. The expression of inflammation-associated mRNAs such as monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-a) and IL-6, and tubular injury score in H-E staining were more reduced in POSTN-null mice than WT mice at 72 h after glycerol injection. CONCLUSION: POSTN was highly expressed in the kidney through rhabdomyolysis and was a positive regulator of AKI. Targeting POSTN might propose a new therapeutic strategy against the development of acute renal failure.

Negative action of hepatocyte growth factor/c-Met system on angiotensin II signaling via ligand-dependent epithelial growth factor receptor degradation mechanism in vascular smooth muscle cells.

RATIONALE: Neointimal hyperplasia contributes to atherosclerosis and restenosis after percutaneous coronary intervention. Vascular injury in each of these conditions results in the release of mitogenic growth factors and hormones that contribute to pathological vascular smooth muscle cell growth and inflammation. Hepatocyte growth factor (HGF) is known as an antiinflammatory growth factor, although it is downregulated in injured tissue. However, the precise mechanism how HGF reduces inflammation is unclear. OBJECTIVE: To elucidate the mechanism how HGF and its receptor c-Met reduces angiotensin II (Ang II)-induced inflammation. METHODS AND RESULTS: HGF reduced Ang II-induced vascular smooth muscle cell growth and inflammation by controlling translocation of SHIP2 (Src homology domain 2-containing inositol 5'-phosphatase 2), which led to Ang II-dependent degradation of epithelial growth factor receptor. Moreover, the present study also revealed a preventive effect of HGF on atherosclerotic change in an Ang II infusion and cuff HGF transgenic mouse model. CONCLUSIONS: These data suggest that the HGF/c-Met system might regulate extrinsic factor signaling that maintains the homeostasis of organs.

Periostin Short Fragment with Exon 17 via Aberrant Alternative Splicing Is Required for Breast Cancer Growth and Metastasis.

BACKGROUND: Periostin (POSTN) is a 93 kDa matrix protein that helps to regulate collagen gene expression in the extracellular matrix. POSTN overexpression is a prognostic factor in malignant cancers; however, some researchers have observed it in the stroma, whereas others have reported it on tumors. OBJECTIVE: This study aimed to investigate the function of POSTN on tumors. METHODS AND RESULTS: We found that POSTN in cancer cells can be detected by using an antibody against the POSTN C-terminal region exon 17 (Ex17 antibody), but not with an antibody against the POSTN N-terminal region exon 12 (Ex12 antibody) in patients with breast cancer. In a fraction secreted from fibroblasts, LC-MS/MS analysis revealed a short fragment of POSTN of approximately 40 kDa with exon 17. In addition, molecular interaction analysis showed that POSTN with exon 17, but not POSTN without exon 17, bound specifically to wnt3a, and the Ex17 antibody inhibited the binding. CONCLUSION: A short fragment of POSTN with exon 17, which originates in the fibroblasts, is transported to cancer cells, whereas POSTN fragments without exon 17 are retained in the stroma. The Ex17 antibody inhibits the binding between POSTN exon 17 and wnt3a.

The Combination of High Levels of Adiponectin and Insulin Resistance Are Affected by Aging in Non-Obese Old Peoples.

Background: Adipokine dysregulation is a key feature of insulin resistance and a metabolic syndrome associated with obesity. Low adiponectin levels are associated with higher risks of cardiovascular diseases (CVD). However, high adiponectin levels have also been associated with increased all-cause and cardiovascular mortality in the elderly. This adiponectin paradox has yet to be clarified, which has hindered our understanding of the biological role of adiponectin. Adipokine dysregulation and insulin resistance are also associated with energy-deprivation conditions, such as frailty in old age. The objective of this study was to investigate the association between plasma adiponectin and insulin resistance using the homeostasis model assessment for insulin resistance (HOMA-IR) classified by age. In particular, we sought to determine the factors of the subjects associated with both high adiponectin levels and HOMA-IR (H-adiponectin/H-HOMA) and high adiponectin levels and low HOMA-IR (H-adiponectin/L-HOMA). Methods: The eligible subjects in this cross-sectional study were 33,216 individuals who had undergone health checkups at the Physical Checkup Center of Sumitomo Hospital between April 2008 and December 2018. After excluding 26,371 individuals who were under 60 years old, 529 who had been taking medications for diabetes mellitus, and 690 with missing data, the present study included 5,673 (3,467 males, 2,206 females) subjects with no missing data. The relationship between serum adiponectin levels and HOMA-IR was assessed using logistic regression models adjusted by clinically relevant factors. Results: In the multivariable logistic regression analysis, age and low BMI were shown to positively correlate with the characteristics of H-adiponectin/H-HOMA. In females, systolic blood pressure was also shown to be an associated factor. Conclusion: In conclusion, this study showed that aging or a low BMI may contribute to high adiponectin levels and insulin resistance.

Periostin Exon-21 Antibody Neutralization of Triple-Negative Breast Cancer Cell-Derived Periostin Regulates Tumor-Associated Macrophage Polarization and Angiogenesis.

Periostin (Pn) is involved in multiple processes of cancer progression. Previously, we reported that Pn expression is correlated with mesenchymal tumor markers and poor prognosis in triple-negative breast cancer (TNBC). In the TNBC xenograft model, chemotherapy increased expression of a Pn alternative splicing variant (ASV) with exon 21, and administration of the neutralizing antibody against Pn with exon 21 (Pn-21 Ab) overcame chemoresistance with a reduction in the mesenchymal cancer cell fraction. In the present study, the role of Pn ASV with exon 21 in TNBC progression has been addressed. We first established a stable cell line carrying a fluorescence-based splicing reporter. Pn-positive TNBC has higher expression of genes related to tumor-associated macrophage (TAM) recruitment and ECM-receptor interaction than Pn-negative cells. In a xenograft model, only Pn-positive cells initiated tumor formation, and the Pn-21 Ab suppressed tumor cell growth, accompanied by decreased M2 TAM polarization and the number of tumor vessels. These data suggest that cancer cell-derived Pn ASV educates TAMs and regulates angiogenesis, which in turn establishes a microenvironmental niche that is supportive of TNBC.

An exosomal-carried short periostin isoform induces cardiomyocyte proliferation.

Although a small number of cardiomyocytes may reenter the cell cycle after injury, the adult mammalian heart is incapable of a robust cardiomyocyte proliferation. Periostin, a secreted extracellular matrix protein, has been implicated as a regulator of cardiomyocyte proliferation; however, this role remains controversial. Alternative splicing of the human periostin gene results in 6 isoforms lacking sequences between exons 17 and 21, in addition to full-length periostin. We previously showed that exosomes (Exo) secreted by human cardiac explant-derived progenitor cells (CPC) carried periostin. Here, we aimed to investigate their cell cycle activity. Methods: CPC were derived as the cellular outgrowth of ex vivo cultured cardiac atrial explants. Exo were purified from CPC conditioned medium using size exclusion chromatography. Exosomal periostin was analyzed by Western blotting using a pair of antibodies (one raised against aa 537-836, and one raised against amino acids mapping at exon 17 of human periostin), by ELISA, and by cryo-EM with immune-gold labeling. Cell cycle activity was assessed in neonatal rat cardiomyocytes, in human induced pluripotent stem cell (iPS)-derived cardiomyocytes, and in adult rat cardiomyocytes after myocardial infarction. The role of periostin in cell cycle activity was investigated by transfecting donor CPC with a siRNA against this protein. Results: Periostin expression in CPC-secreted exosomes was detected using the antibody raised against aa 537-836 of the human protein, but not with the exon 17-specific antibody, consistent with an isoform lacking exon 17. Periostin was visualized on vesicle surfaces by cryo-EM and immune-gold labeling. CPC-derived exosomes induced cell proliferation in neonatal rat cardiomyocytes both in vitro and in vivo, in human iPS-derived cardiomyocytes, and in adult rat cardiomyocytes after myocardial infarction. Exo promoted phosphorylation of focal adhesion kinase (FAK), actin polymerization, and nuclear translocation of Yes-associated protein (YAP) in cardiomyocytes. Knocking down of periostin or YAP, or blocking FAK phosphorylation with PF-573228 nullified Exo-induced proliferation. A truncated human periostin peptide (aa 22-669), but not recombinant human full-length periostin, mimicked the pro-proliferative activity of exosomes. Conclusions: Our results show, for the first time, that CPC-secreted exosomes promote cardiomyocyte cell cycle-reentry via a short periostin isoform expressed on their surfaces, whereas recombinant full-length periostin does not. These findings highlight isoform-specific roles of periostin in cardiomyocyte proliferation.

[Therapeutic angiogenesis for diabetes mellitus related ischemic disease].

The complications of diabetes mellitus have a significant impact on patient survival and quality of life with respect to ischemic disease. Therapeutic gene therapy was performed for peripheral artery disease (PAD) using vascular endothelial growth factor (VEGF), but VEGF gene therapy in phase III clinical trial for PAD did not succeed. Although hepatocyte growth factor (HGF) is also a potent angiogenic growth factor in animal models of ischemia, their characteristics are not the same in clinical trials. In this background, we demonstrated that HGF, but not VEGF, attenuated angiotensin II-induced senescence of endothelial progenitor cells through a reduction of oxidative stress by inhibition of the phosphatidylinositol-3,4,5-triphosphate/Akt pathway. Therapeutic gene therapy still may improve patients with the complications of diabetes mellitus.

Therapeutic Angiogenesis Using HGF Plasmid.

Hepatocyte growth factor (HGF) is secreted from stromal and mesenchymal cells, and its receptor cMet is expressed on various types of cells such as smooth muscle cells, fibroblast, and endothelial cells. HGF stimulates epithelial and endothelial cell proliferation, motility, and morphogenesis in a paracrine and autocrine manner, organizing multistep of angiogenesis in many organs. In addition, HGF is recognized as a potent anti-inflammatory and anti-fibrotic growth factor, which has been proved in several animal studies, including neointimal hyperplasia and acute myocardial infarction model in rodent. Thus, as compared to other angiogenic growth factors, HGF exerts multiple effects on ischemic tissues, accompanied by the regression of tissue inflammation and fibrosis. These data suggest the therapeutic potential of the HGF for peripheral artery disease as it being accompanied with chronic tissue inflammation and fibrosis. In the present narrative review, the pleiotropic action of the HGF that differentiates it from other angiogenic growth factors is discussed first, and later, outcomes of the human clinical study with gene therapy are overviewed.

IGF Binding Protein-5 Induces Cell Senescence.

Cellular senescence is the complex process of deterioration that drives the aging of an organism, resulting in the progressive loss of organ function and eventually phenotypic aging. Senescent cells undergo irreversible growth arrest, usually by inducing telomere shortening. Alternatively, senescence may also occur prematurely in response to various stress stimuli, such as oxidative stress, DNA damage, or activated oncogenes. Recently, it has been shown that IGF binding protein-5 (IGFBP-5) with the induction of the tumor suppressor p53 is upregulated during cellular senescence. This mechanism mediates interleukin-6/gp130-induced premature senescence in human fibroblasts, irradiation-induced premature senescence in human endothelial cells (ECs), and replicative senescence in human ECs independent of insulin-like growth factor I (IGF-I) and IGF-II. Additionally, a link between IGFBP-5, hyper-coagulation, and inflammation, which occur with age, has been implicated. Thus, IGFBP-5 seems to play decisive roles in controlling cell senescence and cell inflammation. In this review, we describe the accumulating evidence for this role of IGFBP-5 including our new finding.