Section of Molecular Medicine

Winston-Salem, NC, United States

Section of Molecular Medicine

Winston-Salem, NC, United States
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Nazli S.A.,Section of Molecular Medicine | Loeser R.F.,University of North Carolina at Chapel Hill | Chubinskaya S.,Rush University Medical Center | Yammani R.R.,Section of Molecular Medicine
Osteoarthritis and Cartilage | Year: 2016

Introduction: Insulin-like growth factor-1 (IGF-1) promotes matrix synthesis and cell survival in cartilage. Chondrocytes from aged and osteoarthritic cartilage have a reduced response to IGF-1. The purpose of this study was to determine the effect of free fatty acids (FFA) present in a high-fat diet on IGF-1 function in cartilage and the role of endoplasmic reticulum (ER) stress. Methods: C57BL/6 male mice were maintained on either a high-fat (60% kcal from fat) or a low-fat (10% kcal from fat) diet for 4 months. Mice were then sacrificed; femoral head cartilage caps were collected and treated with IGF-1 to measure proteoglycan (PG) synthesis. Cultured human chondrocytes were treated with 500 μM FFA palmitate or oleate, followed by stimulation with (100 ng/ml) IGF-1 overnight to measure CHOP (a protein marker for ER stress) and PG synthesis. Human chondrocytes were pre-treated with palmitate or 1 mM 4-phenyl butyric acid (PBA) or 1 μM C-Jun N terminal Kinase (JNK) inhibitor, and IGF-1 function (PG synthesis and signaling) was measured. Results: Cartilage explants from mice on the high fat-diet showed reduced IGF-1 mediated PG synthesis compared to a low-fat group. Treatment of human chondrocytes with palmitate induced expression of CHOP, activated JNK and inhibited IGF-1 function. PBA, a small molecule chemical chaperone that alleviates ER stress rescued IGF-1 function and a JNK inhibitor rescued IGF-1 signaling. Conclusions: Palmitate-induced ER stress inhibited IGF-1 function in chondrocytes/cartilage via activating the mitogen-activated protein (MAP) kinase JNK. This is the first study to demonstrate that ER stress is metabolic factor that regulates IGF-1 function in chondrocytes. © 2017 Osteoarthritis Research Society International.


Liang B.,Section of Molecular Medicine | Wang S.,Section of Molecular Medicine | Wang Q.,Section of Molecular Medicine | Zhang W.,Section of Molecular Medicine | And 5 more authors.
Arteriosclerosis, Thrombosis, and Vascular Biology | Year: 2013

Objective-The endoplasmic reticulum (ER) plays a critical role in ensuring proper folding of newly synthesized proteins. Aberrant ER stress is reported to play a causal role in cardiovascular diseases. However, the effects of ER stress on vascular smooth muscle contractility and blood pressure remain unknown. The aim of this study was to investigate whether aberrant ER stress causes abnormal vasoconstriction and consequent high blood pressure in mice. Methods and Results-ER stress markers, vascular smooth muscle contractility, and blood pressure were monitored in mice. Incubation of isolated aortic rings with tunicamycin or MG132, 2 structurally unrelated ER stress inducers, significantly increased both phenylephrine-induced vasoconstriction and the phosphorylation of myosin light chain (Thr18/Ser19), both of which were abrogated by pretreatment with chemical chaperones or 5-Aminoimidazole-4-carboxamide ribonucleotide and metformin, 2 potent activators for the AMP-activated protein kinase. Consistently, administration of tauroursodeoxycholic acid or 4-phenyl butyric acid, 2 structurally unrelated chemical chaperones, in AMP-activated protein kinase-α2 knockout mice lowered blood pressure and abolished abnormal vasoconstrictor response of AMP-activated protein kinase-α2 knockout mice to phenylephrine. Consistently, tunicamycin (0.01 μg/g per day) infusion markedly increased both systolic and diastolic blood pressure, both of which were ablated by coadministration of 4-phenyl butyric acid. Furthermore, 4-phenyl butyric acid or tauroursodeoxycholic acid, which suppressed angiotensin II infusion-induced ER stress markers in vivo, markedly lowered blood pressure in angiotensin II-infused mice in vivo. Conclusion-We conclude that ER stress increases vascular smooth muscle contractility resulting in high blood pressure, and AMP-activated protein kinase activation mitigates high blood pressure through the suppression of ER stress in vivo. © 2013 American Heart Association, Inc.


Pollard R.D.,Section of Molecular Medicine | Blesso C.N.,University of Connecticut | Zabalawi M.,Section of Molecular Medicine | Fulp B.,Section of Molecular Medicine | And 9 more authors.
Journal of Biological Chemistry | Year: 2015

Studies in human populations have shown a significant correlation between procollagen C-endopeptidase enhancer protein 2 (PCPE2) single nucleotide polymorphisms and plasma HDL cholesterol concentrations. PCPE2, a 52-kDa glycoprotein located in the extracellular matrix, enhances the cleavage of C-terminal procollagen by bone morphogenetic protein 1 (BMP1). Our studies here focused on investigating the basis for the elevated concentration of enlarged plasma HDL in PCPE2-deficient mice to determine whether they protected against diet-induced atherosclerosis. PCPE2-deficient mice were crossed with LDL receptor-deficient mice to obtain LDLr-/-, PCPE2-/- mice, which had elevated HDL levels compared with LDLr-/- mice with similar LDL concentrations. We found that LDLr-/-, PCPE2-/- mice had significantly more neutral lipid and CD68+ infiltration in the aortic root than LDLr-/- mice. Surprisingly, in light of their elevated HDL levels, the extent of aortic lipid deposition in LDLr-/-, PCPE2-/- mice was similar to that reported for LDLr-/-, apoA-I-/- mice, which lack any apoA-I/HDL. Furthermore, LDLr-/-, PCPE2-/- mice had reduced HDL apoA-I fractional clearance and macrophage to fecal reverse cholesterol transport rates compared with LDLr-/- mice, despite a 2-fold increase in liver SR-BI expression. PCPE2 was shown to enhance SR-BI function by increasing the rate of HDL-associated cholesteryl ester uptake, possibly by optimizing SR-BI localization and/or conformation. We conclude that PCPE2 is atheroprotective and an important component of the reverse cholesterol transport HDL system. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.


Okon I.S.,Georgia State University | Ding Y.,Georgia State University | Coughlan K.A.,Section of Molecular Medicine | Wang Q.,Section of Molecular Medicine | And 3 more authors.
Oncotarget | Year: 2016

Neuropilin-1 (NRP-1) has emerged as an important driver of tumor-promoting phenotypes of human malignancies. However, incomplete knowledge exists as to how this single-pass transmembrane receptor mediates pleiotropic tumor-promoting functions. The purpose of this study was to evaluate NRP-1 expression and metastatic properties in 94 endometrial cancer and matching serum specimens and in a lung cancer cell line. We found that NRP-1 expression significantly correlated with increased tumoral expression of vascular endothelial growth factor 2 (VEGFR2) and serum levels of hepatocyte growth factor (HGF) and cell growth-stimulating factor (C-GSF). Tumoral NRP-1 also was positively associated with expression of NEDD9, a pro-metastatic protein. In the highly metastatic lung cancer cell line (H1792), stable LKB1 depletion caused increased migration in vitro and accentuated NRP-1 and NEDD9 expression in vivo. Our findings demonstrate that perturbed expression of these targets correlate with metastatic potential of endometrial and lung tumors, providing clinically-relevant biomarker applications for diagnostic and therapeutic targeting.


PubMed | Section of Molecular Medicine, Georgia State University and The University of Oklahoma Health Sciences Center
Type: Journal Article | Journal: Oncotarget | Year: 2016

Neuropilin-1 (NRP-1) has emerged as an important driver of tumor-promoting phenotypes of human malignancies. However, incomplete knowledge exists as to how this single-pass transmembrane receptor mediates pleiotropic tumor-promoting functions. The purpose of this study was to evaluate NRP-1 expression and metastatic properties in 94 endometrial cancer and matching serum specimens and in a lung cancer cell line. We found that NRP-1 expression significantly correlated with increased tumoral expression of vascular endothelial growth factor 2 (VEGFR2) and serum levels of hepatocyte growth factor (HGF) and cell growth-stimulating factor (C-GSF). Tumoral NRP-1 also was positively associated with expression of NEDD9, a pro-metastatic protein. In the highly metastatic lung cancer cell line (H1792), stable LKB1 depletion caused increased migration in vitro and accentuated NRP-1 and NEDD9 expression in vivo. Our findings demonstrate that perturbed expression of these targets correlate with metastatic potential of endometrial and lung tumors, providing clinically-relevant biomarker applications for diagnostic and therapeutic targeting.


Gazzar M.E.,East Tennessee State University | Church A.,Section of Molecular Medicine | Liu T.,Section of Molecular Medicine | McCall C.E.,Section of Molecular Medicine | McCall C.E.,Wake forest University
Journal of Leukocyte Biology | Year: 2011

Following the TLR-dependent initiation phase of acute systemic proinflammatory responses such as sepsis, an adaptive phase represses or activates a specific pattern of gene expression until the inflammation resolves. Here, we used the THP-1 sepsis cell model of bacterial LPS/endotoxin tolerance to show that TLR4- induced miR-146a supports the feed-forward adaptive processes that silence transcription and disrupt translation of acute proinflammatory genes. First, we found that miR-146a regulates a pathway that promotes the binding of transcription repressor RelB to the TNF-α promoter, a step known to precede histone and DNA modifications, which generate facultative heterochromatin to silence acute proinflammatory genes. However, once RelB binding occurred, miR-146a inhibition could not reverse compacted chromatin, and endotoxin tolerance persisted. Second, we observed that miR- 146a regulates a pathway that supports assembly of the translation repressor complex of TNF-α by preventing the interaction of the RNA-binding protein effector Ago2 and RBM4. We also determined that once endotoxin tolerance is established, and specific genes have been reprogrammed, transcription and translation disruption can be reversed only by simultaneously depleting RelB and inhibiting miR-146a. Thus, miR-146a induction supports the TLR4-dependent shift from initiation to gene-specific repression at two levels. Our results also imply that therapies designed to reverse endotoxin tolerance as potential therapies for sepsis should be directed at the transcription and translation pathways of reprogramming. © Society for Leukocyte Biology.


Long D.L.,Section of Molecular Medicine | Ulici V.,University of North Carolina at Chapel Hill | Chubinskaya S.,Rush University Medical Center | Loeser R.F.,Section of Molecular Medicine | Loeser R.F.,University of North Carolina at Chapel Hill
Osteoarthritis and Cartilage | Year: 2015

Objective: We determined if the epidermal growth factor receptor ligand HB-EGF is produced in cartilage and if it regulates chondrocyte anabolic or catabolic activity. Methods: HB-EGF expression was measured by quantitative PCR using RNA isolated from mouse knee joint tissues and from normal and osteoarthritis (OA) human chondrocytes. Immunohistochemistry was performed on normal and OA human cartilage and meniscus sections. Cultured chondrocytes were treated with fibronectin fragments (FN-f) as a catabolic stimulus and osteogenic protein 1 (OP-1) as an anabolic stimulus. Effects of HB-EGF on cell signaling were analyzed by immunoblotting of selected signaling proteins. MMP-13 was measured in conditioned media, proteoglycan synthesis was measured by sulfate incorporation, and matrix gene expression by quantitative PCR. Results: HB-EGF expression was increased in 12-month old mice at 8 weeks after surgery to induce OA and increased amounts of HB-EGF were noted in human articular cartilage from OA knees. FN-f stimulated chondrocyte HB-EGF expression and HB-EGF stimulated chondrocyte MMP-13 production. However, HB-EGF was not required for FN-f stimulation of MMP-13 production. HB-EGF activated the ERK and p38 MAP kinases and stimulated phosphorylation of Smad1 at an inhibitory serine site which was associated with inhibition of OP-1 mediated proteoglycan synthesis and reduced aggrecan (ACAN) but not COL2A1 expression. Conclusion: HB-EGF is a new factor identified in OA cartilage that promotes chondrocyte catabolic activity while inhibiting anabolic activity suggesting it could contribute to the catabolic-anabolic imbalance seen in OA cartilage. © 2015 Osteoarthritis Research Society International.


Long D.L.,Section of Molecular Medicine | Ulici V.,University of North Carolina at Chapel Hill | Chubinskaya S.,Rush University Medical Center | Loeser R.F.,University of North Carolina at Chapel Hill
Osteoarthritis and Cartilage | Year: 2015

Objective: We determined if the epidermal growth factor receptor ligand HB-EGF is produced in cartilage and if it regulates chondrocyte anabolic or catabolic activity. Methods: HB-EGF expression was measured by quantitative PCR using RNA isolated from mouse knee joint tissues and from normal and osteoarthritis (OA) human chondrocytes. Immunohistochemistry was performed on normal and OA human cartilage and meniscus sections. Cultured chondrocytes were treated with fibronectin fragments (FN-f) as a catabolic stimulus and osteogenic protein 1 (OP-1) as an anabolic stimulus. Effects of HB-EGF on cell signaling were analyzed by immunoblotting of selected signaling proteins. MMP-13 was measured in conditioned media, proteoglycan synthesis was measured by sulfate incorporation, and matrix gene expression by quantitative PCR. Results: HB-EGF expression was increased in 12-month old mice at 8 weeks after surgery to induce OA and increased amounts of HB-EGF were noted in human articular cartilage from OA knees. FN-f stimulated chondrocyte HB-EGF expression and HB-EGF stimulated chondrocyte MMP-13 production. However, HB-EGF was not required for FN-f stimulation of MMP-13 production. HB-EGF activated the ERK and p38 MAP kinases and stimulated phosphorylation of Smad1 at an inhibitory serine site which was associated with inhibition of OP-1 mediated proteoglycan synthesis and reduced aggrecan (ACAN) but not COL2A1 expression. Conclusion: HB-EGF is a new factor identified in OA cartilage that promotes chondrocyte catabolic activity while inhibiting anabolic activity suggesting it could contribute to the catabolic-anabolic imbalance seen in OA cartilage. © 2015 Osteoarthritis Research Society International.

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