A MAP1B-cortactin-Tks5 axis regulates TNBC invasion and tumorigenesis

The microtubule-associated protein MAP1B has been implicated in axonal growth and brain development. We found that MAP1B is highly expressed in the most aggressive and deadliest breast cancer subtype, triple-negative breast cancer (TNBC), but not in other subtypes. Expression of MAP1B was found to be highly correlated with poor prognosis. Depletion of MAP1B in TNBC cells impairs cell migration and invasion concomitant with a defect in tumorigenesis. We found that MAP1B interacts with key components for invadopodia formation, cortactin, and Tks5, the latter of which is a PtdIns(3,4)P2-binding and scaffold protein that localizes to invadopodia. We also found that Tks5 associates with microtubules and supports the association between MAP1B and α-tubulin. In accordance with their interaction, depletion of MAP1B leads to Tks5 destabilization, leading to its degradation via the autophagic pathway. Collectively, these findings suggest that MAP1B is a convergence point of the cytoskeleton to promote malignancy in TNBC and thereby a potential diagnostic and therapeutic target for TNBC.

CD40 is expressed in the subsets of endothelial cells undergoing partial endothelial-mesenchymal transition in tumor microenvironment

Tumor progression and metastasis are regulated by endothelial cells undergoing endothelial-mesenchymal transition (EndoMT), a cellular differentiation process in which endothelial cells lose their properties and differentiate into mesenchymal cells. The cells undergoing EndoMT differentiate through a spectrum of intermediate phases, suggesting that some cells remain in a partial EndoMT state and exhibit an endothelial/mesenchymal phenotype. However, detailed analysis of partial EndoMT has been hampered by the lack of specific markers. Transforming growth factor-β (TGF-β) plays a central role in the induction of EndoMT. Here, we showed that inhibition of TGF-β signaling suppressed EndoMT in a human oral cancer cell xenograft mouse model. By using genetic labeling of endothelial cell lineage, we also established a novel EndoMT reporter cell system, the EndoMT reporter endothelial cells (EMRECs), which allow visualization of sequential changes during TGF-β-induced EndoMT. Using EMRECs, we characterized the gene profiles of multiple EndoMT stages and identified CD40 as a novel partial EndoMT-specific marker. CD40 expression was upregulated in the cells undergoing partial EndoMT, but decreased in the full EndoMT cells. Furthermore, single-cell RNA sequencing analysis of human tumors revealed that CD40 expression was enriched in the population of cells expressing both endothelial and mesenchymal cell markers. Moreover, decreased expression of CD40 in EMRECs enhanced TGF-β-induced EndoMT, suggesting that CD40 expressed during partial EndoMT inhibits transition to full EndoMT. The present findings provide a better understanding of the mechanisms underlying TGF-β-induced EndoMT and will facilitate the development of novel therapeutic strategies targeting EndoMT-driven cancer progression and metastasis.

TGF-β signaling in lymphatic vascular vessel formation and maintenance

Transforming growth factor (TGF)-β and its family members, including bone morphogenetic proteins (BMPs), nodal proteins, and activins, are implicated in the development and maintenance of various organs. Here, we review its role in the lymphatic vascular system (the secondary vascular system in vertebrates), which plays a crucial role in various physiological and pathological processes, participating in the maintenance of the normal tissue fluid balance, immune cell trafficking, and fatty acid absorption in the gut. The lymphatic system is associated with pathogenesis in multiple diseases, including lymphedema, inflammatory diseases, and tumor metastasis. Lymphatic vessels are composed of lymphatic endothelial cells, which differentiate from blood vascular endothelial cells (BECs). Although TGF-β family signaling is essential for maintaining blood vessel function, little is known about the role of TGF-β in lymphatic homeostasis. Recently, we reported that endothelial-specific depletion of TGF-β signaling affects lymphatic function. These reports suggest that TGF-β signaling in lymphatic endothelial cells maintains the structure of lymphatic vessels and lymphatic homeostasis, and promotes tumor lymphatic metastasis. Suppression of TGF-β signaling in lymphatic endothelial cells may therefore be effective in inhibiting cancer metastasis. We highlight recent advances in understanding the roles of TGF-β signaling in the formation and maintenance of the lymphatic system.

Combination therapy of anamorelin with a myostatin inhibitor is advantageous for cancer cachexia in a mouse model

Cancer cachexia is a multifactorial disease that causes continuous skeletal muscle wasting. Thereby, it seems to be a key determinant of cancer‐related death. Although anamorelin, a ghrelin receptor agonist, has been approved in Japan for the treatment of cachexia, few medical treatments for cancer cachexia are currently available. Myostatin (MSTN)/growth differentiation factor 8, which belongs to the transforming growth factor‐β family, is a negative regulator of skeletal muscle mass, and inhibition of MSTN signaling is expected to be a therapeutic target for muscle‐wasting diseases. Indeed, we have reported that peptide‐2, an MSTN‐inhibiting peptide from the MSTN prodomain, alleviates muscle wasting due to cancer cachexia. Herein, we evaluated the therapeutic benefit of myostatin inhibitory D‐peptide‐35 (MID‐35), whose stability and activity were more improved than those of peptide‐2 in cancer cachexia model mice. The biologic effects of MID‐35 were better than those of peptide‐2. Intramuscular administration of MID‐35 effectively alleviated skeletal muscle atrophy in cachexia model mice, and the combination therapy of MID‐35 with anamorelin increased food intake and maximized grip strength, resulting in longer survival. Our results suggest that this combination might be a novel therapeutic tool to suppress muscle wasting in cancer cachexia.

Transgenically expressed Helicobacter pylori CagA in vascular endothelial cells accelerates arteriosclerosis in mice

Arteriosclerosis is intimately associated with cardiovascular diseases. Recently, evidence accumulated that infection with Helicobacter pylori cagA-positive strains, which causes gastritis, peptic ulceration, and gastric cancer, is also involved in the development of arteriosclerosis. The cagA-encoded CagA protein is injected into the attached gastric epithelial cells via the type IV secretion system. We previously showed that CagA-containing exosomes are secreted from CagA-injected gastric epithelial cells and enter the systemic blood circulation, delivering CagA into endothelial cells. In the present study, transgenic mice were established in which CagA was selectively expressed in endothelial cells by Cre-loxP system. Treatment of the mice with a high-fat diet revealed that atherogenic lesions were induced in mice expressing CagA in vascular endothelial cells but not in CagA-nonexpressing mice. To investigate the effects of CagA on endothelial cells, we also established conditional CagA-expressing human vascular endothelial cells using the Tet-on system. Upon induction of CagA, a dramatic change in cell morphology was observed that was concomitantly associated with the loss of the endothelial cells to form tube-like structures. Induction of CagA also activated the pro-inflammatory transcription factor STAT3. Thus, exosome-delivered CagA deregulates signals that activates STAT3 in endothelial cells, which accelerates inflammation that promotes arteriosclerosis/atherosclerosis.

Systemic administration of monovalent follistatin-like 3-Fc-fusion protein increases muscle mass in mice

Targeting the signaling pathway of growth differentiation factor 8 (GDF8), also known as myostatin, has been regarded as a promising strategy to increase muscle mass in the elderly and in patients. Accumulating evidence in animal models and clinical trials has indicated that a rational approach is to inhibit a limited number of transforming growth factor β (TGF-β) family ligands, including GDF8 and activin A, without affecting other members. Here, we focused on one of the endogenous antagonists against TGF-β family ligands, follistatin-like 3 (FSTL3), which mainly binds and neutralizes activins, GDF8, and GDF11. Although bivalent human FSTL3 Fc-fusion protein was rapidly cleared from mouse circulation similar to follistatin (FST)-Fc, monovalent FSTL3-Fc (mono-FSTL3-Fc) generated with the knobs-into-holes technology exhibited longer serum half-life. Systemic administration of mono-FSTL3-Fc in mice induced muscle fiber hypertrophy and increased muscle mass in vivo. Our results indicate that the monovalent FSTL3-based therapy overcomes the difficulties of current anti-GDF8 therapies.

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FSTL3-Fc has a more specific binding profile for TGF-β family ligands than ActRIIB-Fc.

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Bivalent two-armed FSTL3-Fc is rapidly cleared from mouse circulation.

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Monovalent FSTL3-Fc has longer serum half-life and causes systemic muscle hypertrophy.

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ActRIIB-Fc-related side effects are not detected in monovalent FSTL3-Fc-treated mice.

The evolutionarily conserved deubiquitinase UBH1/UCH-L1 augments DAF7/TGF-β signaling, inhibits dauer larva formation, and enhances lung tumorigenesis

Modification of the transforming growth factor β (TGF-β) signaling components by (de)ubiquitination is emerging as a key regulatory mechanism that controls cell signaling responses in health and disease. Here, we show that the deubiquitinating enzyme UBH-1 in Caenorhabditis elegans and its human homolog, ubiquitin C-terminal hydrolase-L1 (UCH-L1), stimulate DAF-7/TGF-β signaling, suggesting that this mode of regulation of TGF-β signaling is conserved across animal species. The dauer larva-constitutive C. elegans phenotype caused by defective DAF-7/TGF-β signaling was enhanced and suppressed, respectively, by ubh-1 deletion and overexpression in the loss-of-function genetic backgrounds of daf7, daf-1/TGF-βRI, and daf4/R-SMAD, but not of daf-8/R-SMAD. This suggested that UBH-1 may stimulate DAF-7/TGF-β signaling via DAF-8/R-SMAD. Therefore, we investigated the effect of UCH-L1 on TGF-β signaling via its intracellular effectors, i.e. SMAD2 and SMAD3, in mammalian cells. Overexpression of UCH-L1, but not of UCH-L3 (the other human homolog of UBH1) or of the catalytic mutant UCH-L1C90A, enhanced TGF-β/SMAD-induced transcriptional activity, indicating that the deubiquitination activity of UCH-L1 is indispensable for enhancing TGF-β/SMAD signaling. We also found that UCH-L1 interacts, deubiquitinates, and stabilizes SMAD2 and SMAD3. Under hypoxia, UCH-L1 expression increased and TGF-β/SMAD signaling was potentiated in the A549 human lung adenocarcinoma cell line. Notably, UCH-L1-deficient A549 cells were impaired in tumorigenesis, and, unlike WT UCH-L1, a UCH-L1 variant lacking deubiquitinating activity was unable to restore tumorigenesis in these cells. These results indicate that UCH-L1 activity supports DAF-7/TGF-β signaling and suggest that UCH-L1's deubiquitination activity is a potential therapeutic target for managing lung cancer.

Peptide-2 from mouse myostatin precursor protein alleviates muscle wasting in cancer-associated cachexia

Cancer cachexia, characterized by continuous muscle wasting, is a key determinant of cancer‐related death; however, there are few medical treatments to combat it. Myostatin (MSTN)/growth differentiation factor 8 (GDF‐8), which is a member of the transforming growth factor‐β family, is secreted in an inactivated form noncovalently bound to the prodomain, negatively regulating the skeletal muscle mass. Therefore, inhibition of MSTN signaling is expected to serve as a therapeutic target for intractable muscle wasting diseases. Here, we evaluated the inhibitory effect of peptide‐2, an inhibitory core of mouse MSTN prodomain, on MSTN signaling. Peptide‐2 selectively suppressed the MSTN signal, although it had no effect on the activin signal. In contrast, peptide‐2 slightly inhibited the GDF‐11 signaling pathway, which is strongly related to the MSTN signaling pathway. Furthermore, we found that the i.m. injection of peptide‐2 to tumor‐implanted C57BL/6 mice alleviated muscle wasting in cancer cachexia. Although peptide‐2 was unable to improve the loss of heart weight and fat mass when cancer cachexia model mice were injected with it, peptide‐2 increased the gastrocnemius muscle weight and muscle cross‐sectional area resulted in the enhanced grip strength in cancer cachexia mice. Consequently, the model mice treated with peptide‐2 could survive longer than those that did not undergo this treatment. Our results suggest that peptide‐2 might be a novel therapeutic candidate to suppress muscle wasting in cancer cachexia.

PDZK1-interacting protein 1 (PDZK1IP1) traps Smad4 protein and suppresses transforming growth factor-β (TGF-β) signaling

Transforming growth factor (TGF)-β signaling in humans is stringently regulated to prevent excessive TGF-β signaling. In tumors, TGF-β signaling can both negatively and positively regulate tumorigenesis dependent on tumor type, but the reason for these opposite effects is unclear. TGF-β signaling is mainly mediated via the Smad-dependent pathway, and herein we found that PDZK1-interacting protein 1 (PDZK1IP1) interacts with Smad4. PDZK1IP1 inhibited both the TGF-β and the bone morphogenetic protein (BMP) pathways without affecting receptor-regulated Smad (R-Smad) phosphorylation. Rather than targeting R-Smad phosphorylation, PDZK1IP1 could interfere with TGF-β- and BMP-induced R-Smad/Smad4 complex formation. Of note, PDZK1IP1 retained Smad4 in the cytoplasm of TGF-β-stimulated cells. To pinpoint PDZK1IP1's functional domain, we created several PDZK1IP1 variants and found that its middle region, from Phe⁴⁰ to Ala⁴⁹, plays a key role in its Smad4-regulating activity. PDZK1IP1 knockdown enhanced the expression of the TGF-β target genes Smad7 and prostate transmembrane protein androgen-induced (TMEPAI) upon TGF-β stimulation. In contrast, PDZK1IP1 overexpression suppressed TGF-β-induced reporter activities, cell migration, and cell growth inhibition. In a xenograft tumor model in which TGF-β was previously shown to elicit tumor-promoting effects, PDZK1IP1 gain of function decreased tumor size and increased survival rates. Taken together, these findings indicate that PDZK1IP1 interacts with Smad4 and thereby suppresses the TGF-β signaling pathway.

TMED10 Protein Interferes with Transforming Growth Factor (TGF)-β Signaling by Disrupting TGF-β Receptor Complex Formation

The intensity and duration of TGF-β signaling determine the cellular biological response. How this is negatively regulated is not well understood. Here, we identified a novel negative regulator of TGF-β signaling, transmembrane p24-trafficking protein 10 (TMED10). TMED10 disrupts the complex formation between TGF-β type I (also termed ALK5) and type II receptors (TβRII). Misexpression studies revealed that TMED10 attenuated TGF-β-mediated signaling. A 20-amino acid-long region from Thr⁹¹ to Glu¹¹⁰ within the extracellular region of TMED10 was found to be crucial for TMED10 interaction with both ALK5 and TβRII. Synthetic peptides corresponding to this region inhibit both TGF-β-induced Smad2 phosphorylation and Smad-dependent transcriptional reporter activity. In a xenograft cancer model, where previously TGF-β was shown to elicit tumor-promoting effects, gain-of-function and loss-of-function studies for TMED10 revealed a decrease and increase in the tumor size, respectively. Thus, we determined herein that TMED10 expression levels are the key determinant for efficiency of TGF-β receptor complex formation and signaling.

Two Cases of Thrombocytopenia, Anasarca, Fever, Reticulin Fibrosis/Renal Failure, and Organomegaly (TAFRO) Syndrome with High Serum Procalcitonin Levels, Including the First Case Complicated with Adrenal Hemorrhaging

Thrombocytopenia, Anasarca, Fever, Reticulin fibrosis/Renal failure, and Organomegaly (TAFRO) syndrome is a recently described systemic inflammatory disorder characterized by thrombocytopenia, anasarca, fever, reticulin fibrosis/renal failure, and organomegaly. It has an acute or subacute onset of unknown etiology, although some pathological features resemble those of multicentric Castleman disease. We here report two cases of TAFRO syndrome. The symptoms and pathological findings in these cases met the 2015 diagnostic criteria. Our cases showed high serum procalcitonin levels, suggesting bacterial infection as an onset trigger. In addition, Case 1 is the first case complicated with adrenal hemorrhaging. Case 2 is the second case of tocilizumab-resistant TAFRO syndrome successfully treated with rituximab.

A case of gradually manifesting McCune-Albright syndrome with a 10-year follow-up

McCune-Albright syndrome (MAS) is characterized by fibrous dysplasia (FD) of bone, café-au-lait skin pigmentation, and precocious puberty. Here we report a case of a 12-year-old girl with MAS presenting sexual precocity as initial signs, followed by FD of bone with her growth. She was referred to our hospital because of breast budding and abnormal genital bleeding at the age of 2.8 years. On physical examination, her height and weight were greater than two standard deviations of the mean ranges. Hormonal analysis revealed an elevated serum estradiol and suppressed luteinizing hormone and follicle-stimulating hormone production. Her bone age had advanced, and a 16-mm monocystic lesion was observed on her right ovary by pelvic ultrasonography. Considering the clinical and paraclinical findings, precocious pseudopuberty was suspected and periodic observations were started. Her estrogen "flare up" was transient and she had repeated similar episodes three times in the following 7 years. She complained of pain in her right hip at the age of 9.6 years, which was diagnosed as FD of bone by fluorodeoxyglucose-positron emission tomography. Although no café-au-lait skin pigmentation was observed, we made a preliminary diagnosis of MAS. Because clinical evidence for MAS can appear later in the course of recurrent autonomous cysts, careful observation and periodical assessments of patients with suspected MAS is necessary.

Transforming growth factor-β signaling enhancement by long-term exposure to hypoxia in a tumor microenvironment composed of Lewis lung carcinoma cells

Transforming growth factor‐β (TGF‐β) is a potent growth inhibitor in normal epithelial cells. However, a number of malignant tumors produce excessive amounts of TGF‐β, which affects the tumor‐associated microenvironment by furthering the progression of tumorigenicity. Although it is known that the tumor‐associated microenvironment often becomes hypoxic, how hypoxia influences TGF‐β signaling in this microenvironment is unknown. We investigated whether TGF‐β signaling is influenced by long‐term exposure to hypoxia in Lewis lung carcinoma (LLC) cells. When the cells were exposed to hypoxia for more than 10 days, their morphology was remarkably changed to a spindle shape, and TGF‐β‐induced Smad2 phosphorylation was enhanced. Concomitantly, TGF‐β‐induced transcriptional activity was augmented under hypoxia, although TGF‐β did not influence the activity of a hypoxia‐responsive reporter. Consistently, hypoxia influenced the expression of several TGF‐β target genes. Interestingly, the expressions of TGF‐β type I receptor (TβRI), also termed activin receptor like kinase‐5 (ALK5), and TGF‐β1 were increased under the hypoxic condition. When we monitored the hypoxia‐inducible factor‐1 (HIF‐1) transcriptional activity by use of green fluorescent protein governed by the hypoxia‐responsive element in LLC cells transplanted into mice, TGF‐β‐induced Smad2 phosphorylation was upregulated in vivo. Our results demonstrate that long‐term exposure to hypoxia might alter responsiveness to TGF‐β signaling and affected the malignancy of LLC cells.

Identification of the minimum peptide from mouse myostatin prodomain for human myostatin inhibition

Myostatin, an endogenous negative regulator of skeletal muscle mass, is a therapeutic target for muscle atrophic disorders. Here, we identified minimum peptides 2 and 7 to effectively inhibit myostatin activity, which consist of 24 and 23 amino acids, respectively, derived from mouse myostatin prodomain. These peptides, which had the propensity to form α-helix structure, interacted to myostatin with KD values of 30-36 nM. Moreover, peptide 2 significantly increased muscle mass in Duchenne muscular dystrophy model mice.

Emerging roles for vasoactive peptides in diagnostic and therapeutic strategies against atherosclerotic cardiovascular diseases

Coronary artery disease (CAD) arising from atherosclerosis remains the most common cause of death and morbidity worldwide, although its risk factors, such as hypertension, dyslipidemia, and diabetes, have been individually treated with increasingly improved outcomes. Therefore, it is important to develop diagnostic and therapeutic windows for CAD. Many classical vasoactive hormones, inflammatory cytokines, and oxidative products have been implicated as potential biomarkers. Our recent studies have shown that high levels of the pro-atherogenic vasoactive agents, serotonin and urotensin II, which are potent vasoconstrictors, can be used as biomarkers for CAD. In subsequent trials, we unraveled anti- and pro-atherogenic roles for more recently identified peptides. Anti-atherogenic peptides include the adipocytokine adiponectin, the neuronal growth factor heregulin-β₁ (neuregulin-1 type I), the incretin hormone, glucagon-like peptide-1 (GLP-1), and a peptide recently identified by an in silico approach, salusin-α. Atherogenic roles have been demonstrated by cellular, animal, and clinical experiments, which indicate that human adiponectin, heregulin-β₁, GLP-1, and salusin-α attenuate the development of atherosclerotic lesions by suppressing macrophage foam cell formation via down-regulation of acyl-CoA:cholesterol acyltransferase-1. Circulating levels of these peptides in the blood are markedly decreased in CAD patients compared with those in non-CAD patients. Receiver operating characteristic curve analyses have shown that salusin-α is the most useful biomarker for detecting CAD among the four peptides examined. Therefore, salusin-α, alone or in various combinations with heregulin-β₁, adiponectin, and/or GLP-1, is a candidate biomarker for predicting CAD. Further, anti-atherogenic peptides could potentially serve as useful therapeutic targets for atherosclerotic cardiovascular diseases.

Short communication: opposing effects of lactoferrin on the proliferation of fibroblasts and epithelial cells from bovine mammary gland

Lactoferrin is present in several physiologic fluids, including milk and colostrum. Recently, evidence has accumulated that lactoferrin acts as a regulator of cell proliferation. Lactoferrin mRNA and protein levels in bovine mammary glands are known to markedly increase after cessation of milking. To clarify the role of bovine lactoferrin (bLF) in mammary involution and remodeling during dry periods, we investigated whether bLF affects the proliferation of cultured cells derived from bovine mammary gland and examined the mechanism underlying the proliferative response to bLF. Addition of bLF to the culture medium increased the proliferation of bovine mammary stromal fibroblasts (bMSF), but decreased that of bovine mammary epithelial cells (bMEC). Proliferation was significantly increased in the bMSF treated with bLF (100μg/mL or greater) as compared with unstimulated cells. The maximal proliferative effect of bLF on bMSF occurred at 1,000μg/mL, such that the proliferation of the bLF-stimulated bMSF was approximately 2.5 times that of unstimulated cells. The bLF increased the production of proliferating cell nuclear antigen and rapid phosphorylation of the p44/p42 mitogen-activated protein kinase in bMSF, but not in bMEC. The bLF-induced proliferation and production of proliferating cell nuclear antigen in bMSF was suppressed by U0126, a specific inhibitor of mitogen-activated protein kinase. Furthermore, treatment with bLF for 24h decreased the mRNA levels of the 3 isoforms of transforming growth factor β in bMSF (16-66%) but upregulated those in bMEC (122-157%). These opposite effects of bLF on the proliferation of epithelial and fibroblast cells and their expression of transforming growth factor β may play a crucial role in bovine mammary involution and remodeling.

Roles of TGF-β family signals in the fate determination of pluripotent stem cells

Members of the transforming growth factor-β (TGF-β) family have been implicated in embryogenesis as well as in the determination of the cell fates of mouse and human embryonic stem (ES) cells, which are characterized by their self-renewal and pluripotency. The cellular responses to TGF-β family signals are divergent depending on the cellular context and local environment. TGF-β family signals play critical roles both in the maintenance of the pluripotent state of ES cells by inducing the expression of Nanog, Oct4, and Sox2, and in their differentiation into various cell types by regulating the expression of master regulatory genes. Moreover, multiple lines of evidence have suggested the importance of TGF-β family signals in establishing induced pluripotent stem (iPS) cells. Since ES and iPS cells have great potential for applications in regenerative medicine, it is critical to figure out the mechanisms underlying their self-renewal, pluripotency, and differentiation. Here, we discuss the roles of TGF-β family ligands and their downstream signaling molecules, Smad proteins, in the maintenance of the pluripotency and lineage specification of mouse and human ES and iPS cells.

C18 ORF1, a novel negative regulator of transforming growth factor-β signaling

Transforming growth factor (TGF)-β signaling is deliberately regulated at multiple steps in its pathway from the extracellular microenvironment to the nucleus. However, how TGF-β signaling is activated or attenuated is not fully understood. We recently identified transmembrane prostate androgen-induced RNA (TMEPAI), which is involved in a negative feedback loop of TGF-β signaling. When we searched for a family molecule(s) for TMEPAI, we found C18ORF1, which, like TMEPAI, possesses two PY motifs and one Smad-interacting motif (SIM) domain. As expected, C18ORF1 could block TGF-β signaling but not bone morphogenetic protein signaling. C18ORF1 bound to Smad2/3 via its SIM and competed with the Smad anchor for receptor activation for Smad2/3 binding to attenuate recruitment of Smad2/3 to the TGF-β type I receptor (also termed activin receptor-like kinase 5 (ALK5)), in a similar fashion to TMEPAI. Knockdown of C18ORF1 prolonged duration of TGF-β-induced Smad2 phosphorylation and concomitantly potentiated the expression of JunB, p21, and TMEPAI mRNAs induced by TGF-β. Consistently, TGF-β-induced cell migration was enhanced by the knockdown of C18ORF1. These results indicate that the inhibitory function of C18ORF1 on TGF-β signaling is similar to that of TMEPAI. However, in contrast to TMEPAI, C18ORF1 was not induced upon TGF-β signaling. Thus, we defined C18ORF1 as a surveillant of steady state TGF-β signaling, whereas TMEPAI might help C18ORF1 to inhibit TGF-β signaling in a coordinated manner when cells are stimulated with high levels of TGF-β.

Stimulatory Effects of Cardiotrophin 1 on Atherosclerosis

Cardiotrophin 1 (CT-1), an interleukin-6 family cytokine, was recently shown to be expressed in the intima of early atherosclerotic lesions in the human carotid artery. CT-1 stimulates proatherogenic molecule expression in human vascular endothelial cells and monocyte migration. However, it has not been reported whether CT-1 accelerates atherosclerosis. This study was performed to examine the stimulatory effects of CT-1 on human macrophage foam cell formation and vascular smooth muscle cell migration and proliferation in vitro, and on the development of atherosclerotic lesions in apolipoprotein E–deficient (ApoE −/− ) mice in vivo. CT-1 was expressed at high levels in endothelial cells and macrophages in both humans and ApoE −/− mice. CT-1 significantly enhanced oxidized low-density lipoprotein–induced foam cell formation associated with increased levels of CD36 and acyl-CoA:cholesterol acyltransferase-1 expression in human monocyte–derived macrophages. CT-1 significantly stimulated the migration, proliferation, and collagen-1 expression in human aortic vascular smooth muscle cells. Four-week infusion of CT-1 into ApoE −/− mice significantly accelerated the development of aortic atherosclerotic lesions with increased monocyte/macrophage infiltration, vascular smooth muscle cell proliferation, and collagen-1 content in the aortic wall. Activation of inflammasome, such as apoptosis-associated speck-like protein containing a caspase recruitment domain, nuclear factor κB, and cyclooxygenase-2, was observed in exudate peritoneal macrophages from ApoE −/− mice infused with CT-1. Infusion of anti–CT-1–neutralizing antibody alone into ApoE −/− mice significantly suppressed monocyte/macrophage infiltration in atherosclerotic lesions. These results indicate that CT-1 accelerates the development of atherosclerotic lesions by stimulating the inflammasome, foam cell formation associated with CD36 and acyl-CoA:cholesterol acyltransferase-1 upregulation in macrophages, and migration, proliferation, and collagen-1 production in vascular smooth muscle cells.

Preventive effect of dipeptidyl peptidase-4 inhibitor on atherosclerosis is mainly attributable to incretin's actions in nondiabetic and diabetic apolipoprotein E-null mice

Aim

Several recent reports have revealed that dipeptidyl peptidase (DPP)-4 inhibitors have suppressive effects on atherosclerosis in apolipoprotein E-null (Apoe^−/−) mice. It remains to be seen, however, whether this effect stems from increased levels of the two active incretins, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP).

Methods

Nontreated Apoe^−/− mice, streptozotocin-induced diabetic Apoe^−/− mice, and db/db diabetic mice were administered the DPP-4 inhibitor vildagliptin in drinking water and co-infused with either saline, the GLP-1 receptor blocker, exendin(9–39), the GIP receptor blocker, (Pro³)GIP, or both via osmotic minipumps for 4 weeks. Aortic atherosclerosis and oxidized low-density lipoprotein-induced foam cell formation in exudate peritoneal macrophages were determined.

Results

Vildagliptin increased plasma GLP-1 and GIP levels without affecting food intake, body weight, blood pressure, or plasma lipid profile in any of the animals tested, though it reduced HbA1c in the diabetic mice. Diabetic Apoe^−/− mice exhibited further-progressed atherosclerotic lesions and foam cell formation compared with nondiabetic counterparts. Nondiabetic and diabetic Apoe^−/− mice showed a comparable response to vildagliptin, namely, remarkable suppression of atherosclerotic lesions with macrophage accumulation and foam cell formation in peritoneal macrophages. Exendin(9–39) or (Pro³)GIP partially attenuated the vildagliptin-induced suppression of atherosclerosis. The two blockers in combination abolished the anti-atherosclerotic effect of vildagliptin in nondiabetic mice but only partly attenuated it in diabetic mice. Vildagliptin suppressed macrophage foam cell formation in nondiabetic and diabetic mice, and this suppressive effect was abolished by infusions with exendin(9–39)+(Pro³)GIP. Incubation of DPP-4 or vildagliptin in vitro had no effect on macrophage foam cell formation.

Conclusions

Vildagliptin confers a substantial anti-atherosclerotic effect in both nondiabetic and diabetic mice, mainly via the action of the two incretins. However, the partial attenuation of atherosclerotic lesions by the dual incretin receptor antagonists in diabetic mice implies that vildagliptin confers a partial anti-atherogenic effect beyond that from the incretins.

Implication of TGF-β as a survival factor during tumour development

Transforming growth factor (TGF)-β is a pleiotropic secretory protein which inhibits and potentiates tumour progression during early and late stage of tumourigenicity, respectively. However, it still remains veiled how TGF-β signalling reveals its two faces. Hoshino et al. (Autocrine TGF-β protects breast cancer cells from apoptosis through reduction of BH3-only protein, Bim, J. Biochem. 2011;149:55-65) demonstrated a new aspect of TGF-β as a survival factor in highly metastatic breast cancer cells from which TGF-β1 and TGF-β3 are abundantly expressed. They found that TGF-β suppressed the expression of BH3-only protein Bim which promotes programmed death signalling via release of cytochrome c from mitochondria. Further interestingly, forkhead box C1 (Foxc1) whose expression is suppressed upon TGF-β stimulation is involved in the expression of Bim. Based on their results, autocrine TGF-β signalling in certain breast cancers promotes cell survival via inhibition of apoptotic signalling. Thus, the inhibitors for activin receptor-like kinase (ALK)5 kinase might exert a curative influence on certain types of metastatic breast cancers.

Endogenous bioactive peptides as potential biomarkers for atherosclerotic coronary heart disease

Cardiovascular disease is the leading cause of death worldwide, with high medical costs and rates of disability. It is therefore important to evaluate the use of cardiovascular biomarkers in the early diagnosis of coronary artery disease (CAD). We have screened a variety of recently identified bioactive peptides candidates in anticipation that they would allow detection of atherosclerotic CAD. Especially, we have focused on novel anti-atherogenic peptides as indicators and negative risk factors for CAD. In vitro, in vivo and clinical studies indicated that human adiponectin, heregulin-β₁, glucagon-like peptide-1 (GLP-1), and salusin-α, peptides of 244, 71, 30, and 28 amino acids, respectively, attenuate the development and progression of atherosclerotic lesions by suppressing macrophage foam cell formation via down-regulation of acyl-coenzyme A: cholesterol acyltransferase-1. Circulating levels of these peptides in the blood are significantly decreased in patients with CAD compared to patients without CAD. Receiver operating characteristic analyses showed that salusin-α is a more useful biomarker, with better sensitivity and specificity, compared with the others for detecting CAD. Therefore, salusin-α, heregulin-β₁, adiponectin, and/or GLP-1, alone or in various combinations, may be useful as biomarkers for atherosclerotic CAD.

Inhibitory machinery for the TGF-β family signaling pathway

Transforming growth factor-β (TGF-β) family signaling regulates cell growth and differentiation of many different cell types and is widely involved in the regulation of homeostasis during both embryogenesis and adult life. Therefore, aberrant TGF-β family signal transduction is linked to congenital disorders, tumorigenicity, and fibrosis, which can be life-threatening. A specific receptor-ligand complex initiates transduction of TGF-β family signaling to the nucleus via intracellular signal molecules, mainly Smads, whereby a number of bioactivities such as wound healing, immunomodulation, apoptosis, and angiogenesis are controlled. To avoid an excess of TGF-β family signaling in cells, the duration and intensity of the TGF-β family signal appear to be subject to elaborate regulation. In this paper, we describe recent advances in the understanding of how TGF-β family signals are perturbed and terminated to maintain homeostasis in cells.

Flk1-GFP BAC Tg mice: an animal model for the study of blood vessel development

The mouse Flk1 (also called Kdr or Vegf-r2) gene encodes a receptor for VEGF-A. Flk1 is expressed in endothelial cells of the developing embryo. Recent studies have shown that Flk1 is expressed by multi-potent mesodermal progenitors, which give rise to various hematopoietic and cardiovascular cell lineages during development, and in differentiating ES cells, which may be used for cell transplantation therapy to treat cardiovascular diseases. Given its developmental and clinical importance in cardiovascular tissues, an animal model of Flk1 activity would be very useful. Here, we report the generation of Flk1-GFP BAC transgenic mice for monitoring Flk1 gene expression during development. We show that GFP expression in these mice serves as a surrogate marker for developing endothelial cells. Immunohistochemical analysis showed that the regions of expression of GFP and endogenous FLK1 largely overlap. Uniform GFP expression was observed in most endothelial cells at 8.5 dpc and thereafter. Flk1-GFP BAC transgenic mice should be useful for the study of both vascular development and pathological angiogenesis.

Requirement of TCF7L2 for TGF-beta-dependent transcriptional activation of the TMEPAI gene

The TGF-β and Wnt pathways are involved in cell fate and tumorigenicity. A recent report indicated that a TGF-β target gene, TMEPAI (transmembrane prostate androgen-induced RNA), is possibly also a downstream target of Wnt signaling. Although TMEPAI was believed to be involved in tumorigenicity because of its blockage of TGF-β signaling, how TGF-β and Wnt signals affect the activation of the TMEPAI gene is not well understood. Herein, we show that the TMEPAI promoter is regulated synergistically by TGF-β/Smad and Wnt/β-catenin/T cell factor (TCF) 7L2. The critical cis-element for dual signals, termed TGF-β-responsive TCF7L2-binding element (TTE), is located in intron 1 of the TMEPAI gene. TCF7L2, but not Smad proteins, bound to TTE, whereas the disruption of TTE by mutagenesis remarkably counteracted both TGF-β and TCF7L2 responses. The introduction of mutations in critical Smad-binding elements blocked the activation of the TMEPAI promoter by TCF7L2. Furthermore, our DNA-protein interaction experiments revealed the indirect binding of TCF7L2 to Smad-binding elements via Smad3 upon TGF-β stimulation as well as its TGF-β-dependent association with TTE. We demonstrate that the Wnt/β-catenin/TCF7L2 pathway is preferentially able to alter the transcriptional regulation of the TGF-β-target gene, TMEPAI.

TMEPAI, a transmembrane TGF-beta-inducible protein, sequesters Smad proteins from active participation in TGF-beta signaling

Transforming growth factor-beta (TGF-beta) is a multifunctional cytokine of key importance for controlling embryogenesis and tissue homeostasis. How TGF-beta signals are attenuated and terminated is not well understood. Here, we show that TMEPAI, a direct target gene of TGF-beta signaling, antagonizes TGF-beta signaling by interfering with TGF-beta type I receptor (TbetaRI)-induced R-Smad phosphorylation. TMEPAI can directly interact with R-Smads via a Smad interaction motif. TMEPAI competes with Smad anchor for receptor activation for R-Smad binding, thereby sequestering R-Smads from TbetaRI kinase activation. In mammalian cells, ectopic expression of TMEPAI inhibited TGF-beta-dependent regulation of plasminogen activator inhibitor-1, JunB, cyclin-dependent kinase inhibitors, and c-myc expression, whereas specific knockdown of TMEPAI expression prolonged duration of TGF-beta-induced Smad2 and Smad3 phosphorylation and concomitantly potentiated cellular responsiveness to TGF-beta. Consistently, TMEPAI inhibits activin-mediated mesoderm formation in Xenopus embryos. Therefore, TMEPAI participates in a negative feedback loop to control the duration and intensity of TGF-beta/Smad signaling.

TAL1/SCL relieves the E2-2-mediated repression of VEGFR2 promoter activity

The basic helix-loop-helix (bHLH) protein TAL1/SCL is essential for embryonic-vascular development. TAL1/SCL regulates the activation of endothelial cells by binding directly or indirectly to DNA sequences in critical target genes. We recently demonstrated that E-box protein E2-2 blocks endothelial cell activation via perturbation of VEGFR2 promoter activity. Herein, we report that TAL1/SCL interacts with E2-2 and inhibits E2-2-mediated effects on reporter activity. Mutational analysis revealed that the HLH domain of TAL1/SCL, but not its basic region, is required for interaction with E2-2. Importantly, TAL1/SCL relieves the E2-2-mediated repression of VEGFR2 reporter activity in endothelial cells. Our data elaborate on the bHLH protein interactions that regulate endothelial cell activation.

Different responses in postprandial plasma ghrelin and GH levels induced by concentrate or timothy hay feeding in wethers

Ghrelin and growth hormone (GH) play a key role in regulating energy balance, metabolic hormone secretion and food intake. Ghrelin and GH responses to dietary compositions have not yet been fully clarified, although there may be significant relationships between dietary compositions and ghrelin and GH responses. In the present study, therefore, we assessed whether dietary compositions influence postprandial plasma ghrelin and GH levels in wethers. Four wethers were respectively fed concentrate (C) or timothy hay (R) for 14 days. The levels of total digestive nutrients (TDN) and crude protein (CP) were adjusted to be at the same level. The basal ghrelin in both groups was rapidly and significantly decreased after feeding. Although the decline of ghrelin levels in C was greater and shorter than that in R, no significant difference was observed in the area under the curve (AUC) or in the incremental area. The plasma GH levels were also rapidly and significantly decreased after feeding in both groups and a significant difference was observed between the two groups for AUC of GH. Interestingly, the circadian changes in the plasma ghrelin levels were close to those in the GH levels in C, but this was not the case in R. These data suggest that dietary compositions influence postprandial plasma ghrelin and GH levels, and that these differences may be caused by several factors, including nutrients and ruminal fermentation.

Changes in gene expression of glucose transporters in lactating and nonlactating cows

Glucose delivery and uptake by the mammary gland are a rate-limiting step in milk synthesis. It is thought that insulin-independent glucose uptake decreases in tissues, except for the mammary gland, and insulin resistance in the whole body increases following the onset of lactation. To study glucose metabolism in peak-, late-, and nonlactating cows, the expression of erythrocyte-type glucose transporter (GLUT1) and the insulin-responsive glucose transporter (GLUT4) in the mammary gland, adipose tissue, and muscle were assessed by Western blotting and real-time PCR. Our results demonstrated that the mammary gland of lactating cows expressed a large amount of GLUT1, whereas the mammary gland of nonlactating cows did not (P < 0.05). On the other hand, adipose tissue of late and nonlactating cows expressed a large amount of GLUT1, whereas the adipose tissue of peak-lactating cows did not (P < 0.05). There were no significant differences in the abundance of GLUT4 mRNA in adipose tissue and muscle, whereas GLUT4 mRNA was not detected in the mammary gland. The plasma insulin concentration was greater (P < 0.05) in nonlactating cows than in peak- and late-lactating cows. The results of the present study indicate that in lactation, GLUT1 expression in the mammary gland and adipose tissue is a major factor for insulin-independent glucose metabolism, and the expression of GLUT4 in muscle and adipose tissue is not an important factor in insulin resistance in lactation; however, the plasma insulin concentration may play a role in insulin-dependent glucose metabolism. Factors other than GLUT4 may be involved in insulin resistance.

Compensatory signalling induced in the yolk sac vasculature by deletion of TGFbeta receptors in mice

Vascular development depends on transforming growth factor beta (TGFbeta), but whether signalling of this protein is required for the development of endothelial cells (ECs), vascular smooth muscle cells (VSMCs) or both is unclear. To address this, we selectively deleted the type I (ALK5, TGFBR1) and type II (TbetaRII, TGFBR2) receptors in mice. Absence of either receptor in ECs resulted in vascular defects in the yolk sac, as seen in mice lacking receptors in all cells, causing embryonic lethality at embryonic day (E)10.5. Deletion of TbetaRII specifically in VSMCs also resulted in vascular defects in the yolk sac; however, these were observed at later stages of development, allowing the embryo to survive to E12.5. Because TGFbeta can also signal in ECs via ALK1 (ACVRL1), we replaced ALK5 by a mutant defective in SMAD2 and SMAD3 (SMAD2/3) activation that retained the ability to transactivate ALK1. This again caused defects in the yolk sac vasculature with embryonic lethality at E10.5, demonstrating that TGFbeta/ALK1 signalling in ECs cannot compensate for the lack of TGFbeta/ALK5-induced SMAD2/3 signalling in vivo. Unexpectedly, SMAD2 phosphorylation and alpha-smooth muscle actin (SMAalpha, ACTA2) expression occurred in the yolk sacs of ALK5(-/-) embryos and ALK5(-/-) embryonic stem cells undergoing vasculogenesis, and these processes could be blocked by an ALK4 (ACVR1B)/ALK5 inhibitor. Together, the data show that ALK5 is required in ECs and VSMCs for yolk sac vasculogenesis; in the absence of ALK5, ALK4 mediates SMAD2 phosphorylation and consequently SMAalpha expression.

Expression of matrilysin (matrix metalloproteinase-7) in primary cutaneous and metastatic melanoma

BACKGROUND

Matrilysin (MMP-7), a member of the matrix metalloproteinase (MMP) family of proteins, is expressed in various types of malignant tumours. There have been no previous studies of the correlation between matrilysin expression and melanoma.

OBJECTIVES

Protein expression of matrilysin was evaluated in human cutaneous melanomas, metastatic melanomas, acquired common melanocytic naevi and Spitz naevi, and the data were corrected with the clinicopathological factors.

METHODS

We retrospectively investigated 18 primary melanomas, 15 metastatic melanomas, 10 common melanocytic naevi and five Spitz naevi samples at our clinic using immunohistochemistry (IHC). Both promatrilysin and active matrilysin were found in the melanoma tissue extracts by Western immunoblotting. In situ hybridization demonstrated that melanoma cells selectively express matrilysin mRNA.

RESULTS

Of the melanoma samples, 29 of 33 (87 x 9%) were positive for matrilysin, including 14 of 18 (77 x 8%) primary cutaneous melanomas and 15 of 15 (100%) metastatic melanomas. In contrast, matrilysin was not expressed in common naevi or Spitz naevi. The matrilysin IHC staining score in primary melanomas was associated with the presence of metastases, tumour thickness and TNM staging (P=0 x 001, 0 x 025 and 0 x 021, respectively). The 5-year overall survival was 26.3% for matrilysin-positive cases and 100% for matrilysin-negative cases among melanoma specimen.

CONCLUSIONS

We found matrilysin expression in primary melanomas and in metastatic melanomas. We further demonstrated that the matrilysin IHC staining score was associated with invasive depth of primary melanoma lesions and metastases. Our observations indicate that matrilysin may be associated with melanoma progression, and may enhance melanoma tumour cell invasion. Therefore, matrilysin may be potentially valuable as a prognostic indicator to predict the clinical behaviour of melanoma.

Frequent epigenetic inactivation of SFRP genes and constitutive activation of Wnt signaling in gastric cancer

Activation of Wnt signaling has been implicated in gastric tumorigenesis, although mutations in APC (adenomatous polyposis coli), CTNNB1 (beta-catenin) and AXIN are seen much less frequently in gastric cancer (GC) than in colorectal cancer. In the present study, we investigated the relationship between activation of Wnt signaling and changes in the expression of secreted frizzled-related protein (SFRP) family genes in GC. We frequently observed nuclear beta-catenin accumulation (13/15; 87%) and detected the active form of beta-catenin in most (12/16; 75%) GC cell lines. CpG methylation-dependent silencing of SFRP1, SFRP2 and SFRP5 was frequently seen among GC cell lines (SFRP1, 16/16, 100%; SFRP2, 16/16, 100%; SFRP5, 13/16, 81%) and primary GC specimens (SFRP1, 42/46, 91%; SFRP2, 44/46, 96%; SFRP5, 30/46, 65%), and treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine rapidly restored SFRP expression. Ectopic expression of SFRPs downregulated T-cell factor/lymphocyte enhancer factor transcriptional activity, suppressed cell growth and induced apoptosis in GC cells. Analysis of global expression revealed that overexpression of SFRP2 repressed Wnt target genes and induced changes in the expression of numerous genes related to proliferation, growth and apoptosis in GC cells. It thus appears that aberrant SFRP methylation is one of the major mechanisms by which Wnt signaling is activated in GC.

ELAC2, a putative prostate cancer susceptibility gene product, potentiates TGF-beta/Smad-induced growth arrest of prostate cells

Transforming growth factor-beta (TGF-beta) elicits a potent growth inhibitory effect on many normal cells by binding to specific serine/threonine kinase receptors and activating specific Smad proteins, which regulate the expression of cell cycle genes, including the p21 cyclin-dependent kinase (CDK) inhibitor gene. Interestingly, cancer cells are often insensitive to the anti-mitogenic effects of TGF-beta for which the molecular mechanisms are not well understood. In this study, we found that the candidate prostate cancer susceptibility gene ELAC2 potentiates TGF-beta/Smad-induced transcriptional responses. ELAC2 associates with activated Smad2; the C-terminal MH2 domain of Smad2 interacts with the N-terminal region of ELAC2. Small interfering siRNA-mediated knock-down of ELAC2 in prostate cells suppressed TGF-beta-induced growth arrest. Moreover, ELAC2 was shown to specifically associate with the nuclear Smad2 partner, FAST-1 and to potentiate the interaction of activated Smad2 with transcription factor Sp1. Furthermore, activation of the p21 CDK inhibitor promoter by TGF-beta is potentiated by ELAC2. Taken together our data indicate an important transcriptional scaffold function for ELAC2 in TGF-beta/Smad signaling mediated growth arrest.

Smad7 and protein phosphatase 1alpha are critical determinants in the duration of TGF-beta/ALK1 signaling in endothelial cells

BACKGROUND

In endothelial cells (EC), transforming growth factor-beta (TGF-beta) can bind to and transduce signals through ALK1 and ALK5. The TGF-beta/ALK5 and TGF-beta/ALK1 pathways have opposite effects on EC behaviour. Besides differential receptor binding, the duration of TGF-beta signaling is an important specificity determinant for signaling responses. TGF-beta/ALK1-induced Smad1/5 phosphorylation in ECs occurs transiently.

RESULTS

The temporal activation of TGF-beta-induced Smad1/5 phosphorylation in ECs was found to be affected by de novo protein synthesis, and ALK1 and Smad5 expression levels determined signal strength of TGF-beta/ALK1 signaling pathway. Smad7 and protein phosphatase 1alpha (PP1alpha) mRNA expression levels were found to be specifically upregulated by TGF-beta/ALK1. Ectopic expression of Smad7 or PP1alpha potently inhibited TGF-beta/ALK1-induced Smad1/5 phosphorylation in ECs. Conversely, siRNA-mediated knockdown of Smad7 or PP1alpha enhanced TGF-beta/ALK1-induced signaling responses. PP1alpha interacted with ALK1 and this association was further potentiated by Smad7. Dephosphorylation of the ALK1, immunoprecipitated from cell lysates, was attenuated by a specific PP1 inhibitor.

CONCLUSION

Our results suggest that upon its induction by the TGF-beta/ALK1 pathway, Smad7 may recruit PP1alpha to ALK1, and thereby control TGF-beta/ALK1-induced Smad1/5 phosphorylation.

Successful treatment of hepatitis B virus-associated membranous nephropathy with lamivudine

We present a case of chronic hepatitis B with membranous nephropathy, that was improved by lamivudine treatment. A 37-year-old man was admitted to our hospital for the evaluation of proteinuria. He was diagnosed as having chronic glomerulonephritis associated with chronic hepatitis B. Histopathological findings of the renal biopsy specimen indicated membranous nephropathy. He suffered from nephrotic syndrome associated with leg edema, which was parallel to the exacerbation of hepatitis. Lamivudine was started for the treatment of hepatitis, which caused the disappearance of serum hepatitis B virus DNA and the normalization of ALT level in 4 weeks. Additionally, proteinuria disappeared 120 weeks after the treatment was started. Lamivudine treatment may remit HBV-associated nephropathy.

Plasma Lipid Concentrations in Preruminant Calves Fed Whole Milk with Whey Protein Isolate

The objective was to investigate the acute effects of retinol acetate added to whey protein isolate (WPI) on postprandial changes in plasma retinol (experiment 1) and the acute effects of milk fat added to WPI on triglyceride (TG), chylomicrons and very low density lipoprotein (VLDL), and fatty acid concentrations (experiment 2) in suckling calves at 1 and 6 wk of age. In experiment 1, 16 Holstein male calves were alloted to 2 equal groups. On the days of measurement, the calves were fed at 0900 h whole milk [4% of body weight (BW)] mixed with vitamin A acetate (500,000 IU) with or without WPI (0.04% of BW). At 1 wk of age, significantly higher postfeeding concentrations of plasma retinol were observed in the calves fed milk with WPI. At 6 wk of age, no differences in the plasma retinol concentrations were observed between 2 groups. On the days of measurement in experiment 2, 16 male calves were fed at 0900 h whole milk (4% of BW) with added milk fat prepared by centrifugation from whole milk (2% of BW) with or without WPI (0.04% of BW). The milk supplemented with fat was prepared on the day before the measurement. At 1 wk of age, significant higher postfeeding concentrations of plasma TG concentrations were obtained in the calves fed WPI than in the control calves, immediately after the meal or from 7 h later onward. Plasma chylomicrons and VLDL concentrations at 1 wk of age were significantly higher in the WPI-fed group than in the control group at 8 h postfeeding. In the calves with the WPI diet, plasma concentrations of myristic, palmitic, stearic, oleic, and linoleic acids at 1 wk of age were significantly higher than those in the control calves at 8 h after feeding. However, chylomicrons and VLDL, and fatty acid concentrations did not differ between the 2 groups after feeding at 6 wk of age. Results indicate that WPI increases plasma lipid concentration of preruminant calves only at 1 wk of age. These data are interpreted to indicate that WPI enhances mainly lipid uptake in the intestines of neonatal calves.

GH secretory responses to ghrelin and GHRH in growing and lactating dairy cattle

Release of growth hormone (GH) is known to be regulated mainly by GH-releasing hormone (GHRH) and somatostatin (SRIF) secreted from the hypothalamus. A novel peripheral release-regulating hormone, ghrelin, was recently identified. In this study, differences of the GH secretory response to ghrelin and GHRH in growing and lactating dairy cattle were investigated and an alteration of plasma ghrelin levels was observed. The same amounts of ghrelin and GHRH (0.3 nmol/kg) were intravenously injected to suckling and weanling calves, early and mid-lactating cows and non-lactating cows. Plasma ghrelin levels were also determined in dairy cattle in various physiological conditions. The peak values of ghrelin-induced GH secretion were increased in early lactating cows compared to those in non-lactating cows. The relative responsiveness of GH secretion to ghrelin was also increased compared with that to GHRH in early lactating cows. GH secretory responses to GHRH were blunted in mature cows with and without lactation. Conversely, GHRH-induced GH secretory response was greater than that to ghrelin in calves, and also greater in calves than in mature cows. Plasma ghrelin concentrations were elevated in early lactating cows compared to those in non-lactating cows. Plasma GH concentrations were higher in suckling calves and early lactating cows compared with those in non-lactating cows. These results suggest that GHRH is an effective inducer of GH release in growing calves, and that the relative importance of ghrelin in contributing to the rise in plasma GH increases in early lactating cows.

Synergy and antagonism between Notch and BMP receptor signaling pathways in endothelial cells

Notch and bone morphogenetic protein signaling pathways are important for cellular differentiation, and both have been implicated in vascular development. In many cases the two pathways act similarly, but antagonistic effects have also been reported. The underlying mechanisms and whether this is caused by an interplay between Notch and BMP signaling is unknown. Here we report that expression of the Notch target gene, Herp2, is synergistically induced upon activation of Notch and BMP receptor signaling pathways in endothelial cells. The synergy is mediated via RBP-Jkappa/CBF-1 and GC-rich palindromic sites in the Herp2 promoter, as well as via interactions between the Notch intracellular domain and Smad that are stabilized by p/CAF. Activated Notch and its downstream effector Herp2 were found to inhibit endothelial cell (EC) migration. In contrast, BMP via upregulation of Id1 expression has been reported to promote EC migration. Interestingly, Herp2 was found to antagonize BMP receptor/Id1-induced migration by inhibiting Id1 expression. Our results support the notion that Herp2 functions as a critical switch downstream of Notch and BMP receptor signaling pathways in ECs.

Distribution of apolipoprotein E among lipoprotein fractions in the lactating cow

Apolipoprotein (apo) E plays a key role in regulating plasma levels of lipoproteins. We investigated the serum apoE concentrations in cows during different lactating stages by ELISA. To confirm the distribution of apoE in lipoprotein fractions, cow plasma was separated by gel filtration, ultracentrifugation and agarose gel electrophoresis. The apoE concentrations during early, mid- and late lactating stages in cows were significantly higher than that during the non-lactating stage. In lactating plasma, apoE eluted in high-density lipoprotein (HDL) fractions separated by gel filtration increased. The portion of this apoE in plasma was 49%. However, when lactating plasma was separated by ultracentrifugation, less then 5% apoE was recovered in the HDL fraction, and more apoE was recovered in the non-lipoprotein fraction (d>1.21 g/ml, 46%). In agarose gel electrophoresis, plasma apoE was found in beta-migrating lipoprotein, but it was not present in alpha-migrating lipoprotein. To purify apoE-containing particles, the HDL fraction separated by gel filtration was pooled and the fraction retained on Heparin-Sepharose chromatography collected. Cholesterol was absent from this fraction. These results suggest that apoE-containing particles, which increased during the lactating stage, were not associated with HDL particles, and that lipid-free forms were included in cow plasma.

Elucidation of Smad requirement in transforming growth factor-beta type I receptor-induced responses

Transforming growth factor-beta (TGF-beta) elicits cellular effects by activating specific Smad proteins that control the transcription of target genes. Whereas there is growing evidence that there are TGF-beta type I receptor-initiated intracellular pathways that are distinct from the pivotal Smad pathway, their physiological importance in TGF-beta signaling is not well understood. Therefore, we generated TGF-beta type I receptors (also termed ALK5s) with mutations in the L45 loop of the kinase domain, termed ALK5(D266A) and ALK5(3A). These mutants showed retained kinase activity but were unable to activate Smads. Characterization of their signaling properties revealed that the two L45 loop mutants did not mediate Smad-dependent transcriptional responses, TGF-beta-induced growth inhibition, and fibronectin and plasminogen activator-1 production in R4-2 mink lung epithelial cells lacking functional ALK5 protein. Mutation in the L45 loop region did not affect the binding of inhibitory Smads but did abrogate the weak binding of X-linked inhibitor of apoptosis protein and Disabled-2 to ALK5. This suggests that the L45 loop in the kinase domain is important for docking of other binding proteins. Interestingly, JNK MAP kinase activity was found to be activated by the ALK5(3A) mutant in various cell types. In addition, TGF-beta-induced inhibition of cyclin D1 expression and stimulation of PMEPA1 (androgen-regulated prostatic mRNA) expression were found to occur, albeit weakly, in an Smad-independent manner in normal murine mammary gland cells. However, the TGF-beta-induced epithelial to mesenchymal transdifferentiation was found to require an intact L45 loop and is likely to be dependent on the Smad pathways.