Metabolic actions of Rho-kinase in periphery and brain

Off-target pharmacological activity at various kinases: Potential functional and pathological side effects

In drug discovery, during the lead optimization and candidate characterization stages, novel small molecules are frequently evaluated in a battery of in vitro pharmacology assays to identify potential unintended, off-target interactions with various receptors, transporters, ion channels, and enzymes, including kinases. Furthermore, these screening panels may also provide utility at later stages of development to provide a mechanistic understanding of unexpected safety findings. Here, we present a compendium of the most likely functional and pathological outcomes associated with interaction(s) to a panel of 95 kinases based on an extensive curation of the scientific literature. This panel of kinases was designed by AbbVie based on safety-related data extracted from the literature, as well as from over 20 years of institutional knowledge generated from discovery efforts. For each kinase, the scientific literature was reviewed using online databases and the most often reported functional and pathological effects were summarized. This work should serve as a practical guide for small molecule drug discovery scientists and clinical investigators to predict and/or interpret adverse effects related to pharmacological interactions with these kinases.

Rho-associated protein kinase 1 inhibition in hepatocytes attenuates nonalcoholic steatohepatitis

BACKGROUND

NASH is the progressive form of NAFLD characterized by lipotoxicity, hepatocyte injury, tissue inflammation, and fibrosis. Previously, Rho-associated protein kinase (ROCK) 1 has been implicated in lipotoxic signaling in hepatocytes in vitro and high-fat diet-induced lipogenesis in vivo. However, whether ROCK1 plays a role in liver inflammation and fibrosis during NASH is unclear. Here, we hypothesized that pathogenic activation of ROCK1 promotes murine NASH pathogenesis.

METHODS AND RESULTS

Patients with NASH had increased hepatic ROCK1 expression compared with patients with fatty liver. Similarly, hepatic ROCK1 levels and activity were increased in mice with NASH induced by a western-like diet that is high in fat, fructose, and cholesterol (FFC). Hepatocyte-specific ROCK1 knockout mice on the FFC diet displayed a decrease in liver steatosis, hepatic cell death, liver inflammation, and fibrosis compared with littermate FFC-fed controls. Mechanistically, these effects were associated with a significant attenuation of myeloid cell recruitment. Interestingly, myeloid cell-specific ROCK1 deletion did not affect NASH development in FFC-fed mice. To explore the therapeutic opportunities, mice with established NASH received ROCKi, a novel small molecule kinase inhibitor of ROCK1/2, which preferentially accumulates in liver tissue. ROCK inhibitor treatment ameliorated insulin resistance and decreased liver injury, inflammation, and fibrosis.

CONCLUSIONS

Genetic or pharmacologic inhibition of ROCK1 activity attenuates murine NASH, suggesting that ROCK1 may be a therapeutic target for treating human NASH.

ROCK1 regulates insulin secretion from β-cells

OBJECTIVE

The endocrine pancreatic β-cells play a pivotal role in maintaining whole-body glucose homeostasis and its dysregulation is a consistent feature in all forms of diabetes. However, knowledge of intracellular regulators that modulate β-cell function remains incomplete. We investigated the physiological role of ROCK1 in the regulation of insulin secretion and glucose homeostasis.

METHODS

Mice lacking ROCK1 in pancreatic β-cells (RIP-Cre; ROCK1^loxP/loxP, β-ROCK1^-/-) were studied. Glucose and insulin tolerance tests as well as glucose-stimulated insulin secretion (GSIS) were measured. An insulin secretion response to a direct glucose or pyruvate or pyruvate kinase (PK) activator stimulation in isolated islets from β-ROCK1^-/- mice or β-cell lines with knockdown of ROCK1 was also evaluated. A proximity ligation assay was performed to determine the physical interactions between PK and ROCK1.

RESULTS

Mice with a deficiency of ROCK1 in pancreatic β-cells exhibited significantly increased blood glucose levels and reduced serum insulin without changes in body weight. Interestingly, β-ROCK1^-/- mice displayed a progressive impairment of glucose tolerance while maintaining insulin sensitivity mostly due to impaired GSIS. Consistently, GSIS markedly decreased in ROCK1-deficient islets and ROCK1 knockdown INS-1 cells. Concurrently, ROCK1 blockade led to a significant decrease in intracellular calcium and ATP levels and oxygen consumption rates in isolated islets and INS-1 cells. Treatment of ROCK1-deficient islets or ROCK1 knockdown β-cells either with pyruvate or a PK activator rescued the impaired GSIS. Mechanistically, we observed that glucose stimulation in β-cells greatly enhanced ROCK1 binding to PK.

CONCLUSIONS

Our findings demonstrate that β-cell ROCK1 is essential for glucose-stimulated insulin secretion and for glucose homeostasis and that ROCK1 acts as an upstream regulator of glycolytic pyruvate kinase signaling.

Rho Kinases in Embryonic Development and Stem Cell Research

The Rho-associated coiled-coil containing kinases (ROCKs or Rho kinases) belong to the AGC (PKA/PKG/PKC) family of serine/threonine kinases and are major downstream effectors of small GTPase RhoA, a key regulator of actin-cytoskeleton reorganization. The ROCK family contains two members, ROCK1 and ROCK2, which share 65% overall identity and 92% identity in kinase domain. ROCK1 and ROCK2 were assumed to be functionally redundant, based largely on their major common activators, their high degree kinase domain homology, and study results from overexpression with kinase constructs or chemical inhibitors. ROCK signaling research has expanded to all areas of biology and medicine since its discovery in 1996. The rapid advance is befitting ROCK’s versatile functions in modulating various cell behavior, such as contraction, adhesion, migration, proliferation, polarity, cytokinesis, and differentiation. The rapid advance is noticeably driven by an extensive linking with clinical medicine, including cardiovascular abnormalities, aberrant immune responsive, and cancer development and metastasis. The rapid advance during the past decade is further powered by novel biotechnologies including CRISPR-Cas and single cell omics. Current consensus, derived mainly from gene targeting and RNA interference approaches, is that the two ROCK isoforms have overlapping and distinct cellular, physiological and pathophysiology roles. In this review, we present an overview of the milestone discoveries in ROCK research. We then focus on the current understanding of ROCK signaling in embryonic development, current research status using knockout and knockin mouse models, and stem cell research.

Insight Into Rho Kinase Isoforms in Obesity and Energy Homeostasis

Obesity and associated complications increasingly jeopardize global health and contribute to the rapidly rising prevalence of type 2 diabetes mellitus and obesity-related diseases. Developing novel methods for the prevention and treatment of excess body adipose tissue expansion can make a significant contribution to public health. Rho kinase is a Rho-associated coiled-coil-containing protein kinase (Rho kinase or ROCK). The ROCK family including ROCK1 and ROCK2 has recently emerged as a potential therapeutic target for the treatment of metabolic disorders. Up-regulated ROCK activity has been involved in the pathogenesis of all aspects of metabolic syndrome including obesity, insulin resistance, dyslipidemia and hypertension. The RhoA/ROCK-mediated actin cytoskeleton dynamics have been implicated in both white and beige adipogenesis. Studies using ROCK pan-inhibitors in animal models of obesity, diabetes, and associated complications have demonstrated beneficial outcomes. Studies via genetically modified animal models further established isoform-specific roles of ROCK in the pathogenesis of metabolic disorders including obesity. However, most reported studies have been focused on ROCK1 activity during the past decade. Due to the progress in developing ROCK2-selective inhibitors in recent years, a growing body of evidence indicates more attention should be devoted towards understanding ROCK2 isoform function in metabolism. Hence, studying individual ROCK isoforms to reveal their specific roles and principal mechanisms in white and beige adipogenesis, insulin sensitivity, energy balancing regulation, and obesity development will facilitate significant breakthroughs for systemic treatment with isoform-selective inhibitors. In this review, we give an overview of ROCK functions in the pathogenesis of obesity and insulin resistance with a particular focus on the current understanding of ROCK isoform signaling in white and beige adipogenesis, obesity and thermogenesis in adipose tissue and other major metabolic organs involved in energy homeostasis regulation.

Circ_0057558 promotes nonalcoholic fatty liver disease by regulating ROCK1/AMPK signaling through targeting miR-206

Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic liver disorders that is featured by the extensive deposition of fat in the hepatocytes. Current treatments are very limited due to its unclear pathogenesis. Here, we investigated the function of circ_0057558 and miR-206 in NAFLD. High-fat diet (HFD) feeding mouse was used as an in vivo NAFLD model and long-chain-free fatty acid (FFA)-treated liver cells were used as an in vitro NAFLD model. qRT-PCR was used to measure levels of miR-206, ROCK1 mRNA, and circ_0057558, while Western blotting was employed to determine protein levels of ROCK1, p-AMPK, AMPK, and lipogenesis-related proteins. Immunohistochemistry were performed to examine ROCK1 level. Oil-Red O staining was used to assess the lipid deposition in cells. ELISA was performed to examine secreted triglyceride (TG) level. Dual-luciferase assay was used to validate interactions of miR-206/ROCK1 and circ_0057558/miR-206. RNA immunoprecipitation was employed to confirm the binding of circ_0057558 with miR-206. Circ_0057558 was elevated while miR-206 was reduced in both in vivo and in vitro NAFLD models. miR-206 directly bound with ROCK1 3'-UTR and suppressed lipogenesis and TG secretion through targeting ROCK1/AMPK signaling. Circ_0057558 directly interacted with miR-206 to disinhibit ROCK1/AMPK signaling. Knockdown of circ_0057558 or overexpression of miR-206 inhibited lipogenesis, TG secretion and expression of lipogenesis-related proteins. ROCK1 knockdown reversed the effects of circ_0057558 overexpression. Injection of miR-206 mimics significantly ameliorated NAFLD progression in vivo. Circ_0057558 acts as a miR-206 sponge to de-repress the ROCK1/AMPK signaling and facilitates lipogenesis and TG secretion, which greatly contributes to NAFLD development and progression.

TEM8 marks neovasculogenic tumor-initiating cells in triple-negative breast cancer

Enhanced neovasculogenesis, especially vasculogenic mimicry (VM), contributes to the development of triple-negative breast cancer (TNBC). Breast tumor-initiating cells (BTICs) are involved in forming VM; however, the specific VM-forming BTIC population and the regulatory mechanisms remain undefined. We find that tumor endothelial marker 8 (TEM8) is abundantly expressed in TNBC and serves as a marker for VM-forming BTICs. Mechanistically, TEM8 increases active RhoC level and induces ROCK1-mediated phosphorylation of SMAD5, in a cascade essential for promoting stemness and VM capacity of breast cancer cells. ASB10, an estrogen receptor ERα trans-activated E3 ligase, ubiquitylates TEM8 for degradation, and its deficiency in TNBC resulted in a high homeostatic level of TEM8. In this work, we identify TEM8 as a functional marker for VM-forming BTICs in TNBC, providing a target for the development of effective therapies against TNBC targeting both BTIC self-renewal and neovasculogenesis simultaneously.

Vasculogenic mimicry (VM) contributes to the development of triple-negative breast cancer. In this study, the authors show that TEM8 is expressed in VM-forming breast cancer stem cells and it promotes stemness and VM differentiation capacity through a RhoC/ROCK1/SMAD5 axis

A Cell-Autonomous Signature of Dysregulated Protein Phosphorylation Underlies Muscle Insulin Resistance in Type 2 Diabetes

Skeletal muscle insulin resistance is the earliest defect in type 2 diabetes (T2D), preceding and predicting disease development. To what extent this reflects a primary defect or is secondary to tissue cross talk due to changes in hormones or circulating metabolites is unknown. To address this question, we have developed an in vitro disease-in-a-dish model using iPS cells from T2D patients differentiated into myoblasts (iMyos). We find that T2D iMyos in culture exhibit multiple defects mirroring human disease, including an altered insulin signaling, decreased insulin-stimulated glucose uptake, and reduced mitochondrial oxidation. More strikingly, global phosphoproteomic analysis reveals a multidimensional network of signaling defects in T2D iMyos going beyond the canonical insulin-signaling cascade, including proteins involved in regulation of Rho GTPases, mRNA splicing and/or processing, vesicular trafficking, gene transcription, and chromatin remodeling. These cell-autonomous defects and the dysregulated network of protein phosphorylation reveal a new dimension in the cellular mechanisms underlying the fundamental defects in T2D.

Physical exercise increases ROCK activity in the skeletal muscle of middle-aged rats

The physical exercise is a potential strategy to control age-related metabolic disorders, such as insulin resistance, impaired glucose homeostasis, and type 2 diabetes. Rho-kinase (ROCK) increases skeletal muscle glucose uptake through Insulin Receptor Substrate 1 (IRS1) phosphorylation. Here, we investigated the role of physical exercise in ROCK pathway in the skeletal muscle of Fischer middle-aged rats. Firstly, we observed the ROCK distribution in different skeletal muscle fiber types. ROCK signaling pathway (ROCK1 and ROCK2) and activity (pMYPT1) were higher in the soleus, which was associated with increased insulin signaling pathway (pIR, pIRS1, pPDK, pGSK3β). Middle-aged rats submitted to physical exercise, showed the upregulation of ROCK2 content and normalized RhoA (ROCK activator enzyme) levels in soleus muscle compared with middle-aged sedentary rats. These molecular changes in middle-aged exercised rats were accompanied by higher insulin signaling (pIRS1, pGSK3β, pAS160, GLUT4) in the soleus muscle. Reinforcing these findings, when pharmacological inhibition of ROCK activity was performed (using Y-27632), the insulin signaling pathway and glucose metabolism-related genes (Tpi, Pgk1, Pgam2, Eno3) were decreased in the soleus muscle of exercised rats. In summary, ROCK signaling seems to contribute with whole-body glucose homeostasis (∼50 %) through its higher upregulation in the soleus muscle in middle-aged exercised rats.

Rock protein as cardiac hypertrophy modulator in obesity and physical exercise

Obesity and cardiovascular diseases are worldwide public health issues. In this review, we discussed the participation of ROCK protein in cardiac hypertrophy, mainly through the modulation of leptin and insulin signaling pathways. Leptin plays a role in cardiovascular disease development and, through the Rho-associated protein kinase (ROCK), promotes cardiac hypertrophy. ROCK protein, is regulated by small Rho-GTPases and has two isoforms with high homology. ROCK is able to activate the MAP kinase (MAPK) pathway and modulate insulin signaling in the heart, participating in cardiac hypertrophy development of concentric and eccentric left ventricle growth. Although different types of stimulus can lead to morphologically antagonistic heart growth, physical exercise promotes improvements in hemodynamic function, emerging as a promising non-pharmacological tool to improve overall health. Leptin can activate ROCK in a pathological way, increasing MAPK activity and decreasing insulin signaling via insulin receptor substrate 1 (IRS1) serine 307 residue phosphorylation, phosphatase and tensin homolog, and protein kinase Cβ2. In turn, physical exercise decreases leptin levels and positively modulates insulin signaling as well as increases ROCK-dependent IRS1 (Ser632/635) phosphorylation, improving phosphatidylinositol 3-kinase/protein kinase B axis and promoting physiologic heart growth. Currently, there is a lack of studies about differences in ROCK isoforms, especially during exercise and/or obesity. However, the understanding of its biological function and the complex mechanism underlying the distinct types of cardiac hypertrophy development can be a useful tool in the improvement and treatment of cardiovascular outcomes.

Role of POMC and AgRP neuronal activities on glycaemia in mice

Leptin regulates both feeding and glycaemia primarily through its receptors expressed on agouti-related peptide (AgRP) and pro-opiomelanocortin-expressing (POMC) neurons; however, it is unknown whether activity of these neuronal populations mediates the regulation of these processes. To determine this, we injected Cre-dependent designer receptors exclusively activated by designer drugs (DREADD) viruses into the hypothalamus of normoglycaemic and diabetic AgRP-ires-cre and POMC-cre mice to chemogenetically activate or inhibit these neuronal populations. Despite robust changes in food intake, activation or inhibition of AgRP neurons did not affect glycaemia, while activation caused significant (P = 0.014) impairment in insulin sensitivity. Stimulation of AgRP neurons in diabetic mice reversed leptin’s ability to inhibit feeding but did not counter leptin’s ability to lower blood glucose levels. Notably, the inhibition of POMC neurons stimulated feeding while decreasing glucose levels in normoglycaemic mice. The findings suggest that leptin’s effects on feeding by AgRP neurons are mediated by changes in neuronal firing, while the control of glucose balance by these cells is independent of chemogenetic activation or inhibition. The firing-dependent glucose lowering mechanism within POMC neurons is a potential target for the development of novel anti-diabetic medicines.

Rho GTPases-Emerging Regulators of Glucose Homeostasis and Metabolic Health

Rho guanosine triphosphatases (GTPases) are key regulators in a number of cellular functions, including actin cytoskeleton remodeling and vesicle traffic. Traditionally, Rho GTPases are studied because of their function in cell migration and cancer, while their roles in metabolism are less documented. However, emerging evidence implicates Rho GTPases as regulators of processes of crucial importance for maintaining metabolic homeostasis. Thus, the time is now ripe for reviewing Rho GTPases in the context of metabolic health. Rho GTPase-mediated key processes include the release of insulin from pancreatic β cells, glucose uptake into skeletal muscle and adipose tissue, and muscle mass regulation. Through the current review, we cast light on the important roles of Rho GTPases in skeletal muscle, adipose tissue, and the pancreas and discuss the proposed mechanisms by which Rho GTPases act to regulate glucose metabolism in health and disease. We also describe challenges and goals for future research.

The Cord Blood Insulin and Mitochondrial DNA Content Related Methylome

Mitochondrial dysfunction seems to play a key role in the etiology of insulin resistance. At birth, a link has already been established between mitochondrial DNA (mtDNA) content and insulin levels in cord blood. In this study, we explore shared epigenetic mechanisms of the association between mtDNA content and insulin levels, supporting the developmental origins of this link. First, the association between cord blood insulin and mtDNA content in 882 newborns of the ENVIRONAGE birth cohort was assessed. Cord blood mtDNA content was established via qPCR, while cord blood levels of insulin were determined using electrochemiluminescence immunoassays. Then the cord blood DNA methylome and transcriptome were determined in 179 newborns, using the human 450K methylation Illumina and Agilent Whole Human Genome 8 × 60 K microarrays, respectively. Subsequently, we performed an epigenome-wide association study (EWAS) adjusted for different maternal and neonatal variables. Afterward, we focused on the 20 strongest associations based on p-values to assign transcriptomic correlates and allocate corresponding pathways employing the R packages ReactomePA and RDAVIDWebService. On the regional level, we examined differential methylation using the DMRcate and Bumphunter packages in R. Cord blood mtDNA content and insulin were significantly correlated (r = 0.074, p = 0.028), still showing a trend after additional adjustment for maternal and neonatal variables (p = 0.062). We found an overlap of 33 pathways which were in common between the association with cord blood mtDNA content and insulin levels, including pathways of neurodevelopment, histone modification, cytochromes P450 (CYP)-metabolism, and biological aging. We further identified a DMR annotated to Repulsive Guidance Molecule BMP Co-Receptor A (RGMA) linked to cord blood insulin as well as mtDNA content. Metabolic variation in early life represented by neonatal insulin levels and mtDNA content might reflect or accommodate alterations in neurodevelopment, histone modification, CYP-metabolism, and aging, indicating etiological origins in epigenetic programming. Variation in metabolic hormones at birth, reflected by molecular changes, might via these alterations predispose children to metabolic diseases later in life. The results of this study may provide important markers for following targeted studies.

Rho-kinase/AMPK axis regulates hepatic lipogenesis during overnutrition

Obesity is a major risk factor for developing nonalcoholic fatty liver disease (NAFLD). NAFLD is the most common form of chronic liver disease and is closely associated with insulin resistance, ultimately leading to cirrhosis and hepatocellular carcinoma. However, knowledge of the intracellular regulators of obesity-linked fatty liver disease remains incomplete. Here we showed that hepatic Rho-kinase 1 (ROCK1) drives obesity-induced steatosis in mice through stimulation of de novo lipogenesis. Mice lacking ROCK1 in the liver were resistant to diet-induced obesity owing to increased energy expenditure and thermogenic gene expression. Constitutive expression of hepatic ROCK1 was sufficient to promote adiposity, insulin resistance, and hepatic lipid accumulation in mice fed a high-fat diet. Correspondingly, liver-specific ROCK1 deletion prevented the development of severe hepatic steatosis and reduced hyperglycemia in obese diabetic (ob/ob) mice. Of pathophysiological significance, hepatic ROCK1 was markedly upregulated in humans with fatty liver disease and correlated with risk factors clustering around NAFLD and insulin resistance. Mechanistically, we found that hepatic ROCK1 suppresses AMPK activity and a ROCK1/AMPK pathway is necessary to mediate cannabinoid-induced lipogenesis in the liver. Furthermore, treatment with metformin, the most widely used antidiabetes drug, reduced hepatic lipid accumulation by inactivating ROCK1, resulting in activation of AMPK downstream signaling. Taken together, our findings establish a ROCK1/AMPK signaling axis that regulates de novo lipogenesis, providing a unique target for treating obesity-related metabolic disorders such as NAFLD.

Evolving mechanisms of vascular smooth muscle contraction highlight key targets in vascular disease

Vascular smooth muscle (VSM) plays an important role in the regulation of vascular function. Identifying the mechanisms of VSM contraction has been a major research goal in order to determine the causes of vascular dysfunction and exaggerated vasoconstriction in vascular disease. Major discoveries over several decades have helped to better understand the mechanisms of VSM contraction. Ca2+ has been established as a major regulator of VSM contraction, and its sources, cytosolic levels, homeostatic mechanisms and subcellular distribution have been defined. Biochemical studies have also suggested that stimulation of Gq protein-coupled membrane receptors activates phospholipase C and promotes the hydrolysis of membrane phospholipids into inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). IP3 stimulates initial Ca2+ release from the sarcoplasmic reticulum, and is buttressed by Ca2+ influx through voltage-dependent, receptor-operated, transient receptor potential and store-operated channels. In order to prevent large increases in cytosolic Ca2+ concentration ([Ca2+]c), Ca2+ removal mechanisms promote Ca2+ extrusion via the plasmalemmal Ca2+ pump and Na+/Ca2+ exchanger, and Ca2+ uptake by the sarcoplasmic reticulum and mitochondria, and the coordinated activities of these Ca2+ handling mechanisms help to create subplasmalemmal Ca2+ domains. Threshold increases in [Ca2+]c form a Ca2+-calmodulin complex, which activates myosin light chain (MLC) kinase, and causes MLC phosphorylation, actin-myosin interaction, and VSM contraction. Dissociations in the relationships between [Ca2+]c, MLC phosphorylation, and force have suggested additional Ca2+ sensitization mechanisms. DAG activates protein kinase C (PKC) isoforms, which directly or indirectly via mitogen-activated protein kinase phosphorylate the actin-binding proteins calponin and caldesmon and thereby enhance the myofilaments force sensitivity to Ca2+. PKC-mediated phosphorylation of PKC-potentiated phosphatase inhibitor protein-17 (CPI-17), and RhoA-mediated activation of Rho-kinase (ROCK) inhibit MLC phosphatase and in turn increase MLC phosphorylation and VSM contraction. Abnormalities in the Ca2+ handling mechanisms and PKC and ROCK activity have been associated with vascular dysfunction in multiple vascular disorders. Modulators of [Ca2+]c, PKC and ROCK activity could be useful in mitigating the increased vasoconstriction associated with vascular disease.

Gene expression analysis identify a metabolic and cell function alterations as a hallmark of obesity without metabolic syndrome in peripheral blood, a pilot study

BACKGROUND

Understanding molecular basis involved in overweight is an important first step in developing therapeutic pathways against excess in body weight gain.

OBJECTIVE

The purpose of our pilot study was to evaluate the gene expression profiles in the peripheral blood of obese patients without other metabolic complications.

DESIGN

A sample of 17 obese patients without metabolic syndrome and 15 non obese control subjects was evaluated in a prospective way. Following 'One-Color Microarray-Based Gene Expression Analysis' protocol Version 5.7 (Agilent p/n 4140-90040), cRNA was hybridized with Whole Human Genome Oligo Microarray Kit (Agilent p/n G2519F-014850) containing 41,000+ unique human genes and transcripts.

RESULTS

The average age of the study group was 43.6 ± 19.7 years with a sex distribution of 64.7% females and 35.3% males. No statistical differences were detected with healthy controls 41.9 ± 12.3 years with a sex distribution of 70% females and 30% males. Obese patients showed 1436 genes that were differentially expressed compared to control group. Ingenuity Pathway Analysis showed that these genes participated in 13 different categories related to metabolism and cellular functions. In the gene set of cellular function, the most important genes were C-terminal region of Nel-like molecule 1 protein (NELL1) and Pigment epithelium-derived factor (SPEDF), both genes were over-expressed. In the gene set of metabolism, insulin growth factor type 1 (IGF1), ApoA5 (apolipoprotein subtype 5), Foxo4 (Forkhead transcription factor 4), ADIPOR1 (receptor of adiponectin type 1) and AQP7 (aquaporin channel proteins7) were over expressed. Moreover, PIKFYVE (PtdIns(3) P 5-kinase), and ROCK-2 (rho-kinase II) were under expressed.

CONCLUSION

We showed that PBMCs from obese subjects presented significant changes in gene expression, exhibiting 1436 differentially expressed genes compared to PBMCs from non-obese subjects. Furthermore, our data showed a number of genes involved in relevant processes implicated in metabolism, with genes presenting high fold-change values (up-regulation and down regulation) associated with lipid, carbohydrate and protein metabolism.

Functions of Rho family of small GTPases and Rho-associated coiled-coil kinases in bone cells during differentiation and mineralization

BACKGROUND

Members of Rho-associated coiled-coil kinases (ROCKs) are effectors of Rho family of small GTPases. ROCKs have multiple functions that include regulation of cellular contraction and polarity, adhesion, motility, proliferation, apoptosis, differentiation, maturation and remodeling of the extracellular matrix (ECM).

SCOPE OF THE REVIEW

Here, we focus on the action of RhoA and RhoA effectors, ROCK1 and ROCK2, in cells related to tissue mineralization: mesenchymal stem cells, chondrocytes, preosteoblasts, osteoblasts, osteocytes, lining cells and osteoclasts.

MAJOR CONCLUSIONS

The activation of the RhoA/ROCK pathway promotes stress fiber formation and reduces chondrocyte and osteogenic differentiations, in contrast to that in mesenchymal stem cells which stimulated the osteogenic and the chondrogenic differentiation. The effects of Rac1 and Cdc42 in promoting chondrocyte hypertrophy and of Rac1, Rac2 and Cdc42 in osteoclast are discussed. In addition, members of the Rho family of GTPases such Rac1, Rac2, Rac3 and Cdc42, acting upstream of ROCK and/or other protein effectors, may compensate the actions of RhoA, affecting directly or indirectly the actions of ROCKs as well as other protein effectors.

GENERAL SIGNIFICANCE

ROCK activity can trigger cartilage degradation and affect bone formation, therefore these kinases may represent a possible therapeutic target to treat osteoarthritis and osseous diseases. Inhibition of Rho/ROCK activity in chondrocytes prevents cartilage degradation, stimulate mineralization of osteoblasts and facilitate bone formation around implanted metals. Treatment with osteoprotegerin results in a significant decrease in the expression of Rho GTPases, ROCK1 and ROCK2, reducing bone resorption. Inhibition of ROCK signaling increases osteoblast differentiation in a topography-dependent manner.

The Effect of Sustained Inflammation on Hepatic Mevalonate Pathway Results in Hyperglycemia

Control of plasma glucose level is essential to organismal survival. Sustained inflammation has been implicated in control of glucose homeostasis in cases of infection, obesity, and type 2 diabetes; however, the precise role of inflammation in these complex disease states remains poorly understood. Here, we find that sustained inflammation results in elevated plasma glucose due to increased hepatic glucose production. We find that sustained inflammation suppresses CYP7A1, leading to accumulation of intermediate metabolites at the branch point of the mevalonate pathway. This results in prenylation of RHOC, which is concomitantly induced by inflammatory cytokines. Subsequent activation of RHO-associated protein kinase results in elevated plasma glucose. These findings uncover an unexpected mechanism by which sustained inflammation alters glucose homeostasis.

Novel Insights into the Roles of Rho Kinase in Cancer

Rho-associated coiled-coil kinase (ROCK) is a major downstream effector of the small GTPase RhoA. The ROCK family, consisting of ROCK1 and ROCK2, plays a central role in the organization of the actin cytoskeleton, and is involved in a wide range of fundamental cellular functions such as contraction, adhesion, migration, proliferation, and apoptosis. Since the discovery of effective inhibitors such as fasudil and Y27632, the biological roles of ROCK have been extensively explored in numerous diseases, including cancer. Accumulating evidence supports the concept that ROCK plays important roles in tumor development and progression through regulating many key cellular functions associated with malignancy, including tumorigenicity, tumor growth, metastasis, angiogenesis, tumor cell apoptosis/survival and chemoresistance as well. This review focuses on the new advances of the most recent 5 years from the studies on the roles of ROCK in cancer development and progression; the discussion is mainly focused on the potential value of ROCK inhibitors in cancer therapy.

p21-Activated protein kinases and their emerging roles in glucose homeostasis

p21-Activated protein kinases (PAKs) are centrally involved in a plethora of cellular processes and functions. Their function as effectors of small GTPases Rac1 and Cdc42 has been extensively studied during the past two decades, particularly in the realms of cell proliferation, apoptosis, and hence tumorigenesis, as well as cytoskeletal remodeling and related cellular events in health and disease. In recent years, a large number of studies have shed light onto the fundamental role of group I PAKs, most notably PAK1, in metabolic homeostasis. In skeletal muscle, PAK1 was shown to mediate the function of insulin on stimulating GLUT4 translocation and glucose uptake, while in pancreatic β-cells, PAK1 participates in insulin granule localization and vesicle release. Furthermore, we demonstrated that PAK1 mediates the cross talk between insulin and Wnt/β-catenin signaling pathways and hence regulates gut proglucagon gene expression and the production of the incretin hormone glucagon-like peptide-1 (GLP-1). The utilization of chemical inhibitors of PAK and the characterization of Pak1(-/-) mice enabled us to gain mechanistic insights as well as to assess the overall contribution of PAKs in metabolic homeostasis. This review summarizes our current understanding of PAKs, with an emphasis on the emerging roles of PAK1 in glucose homeostasis.

ROCK1 isoform-specific deletion reveals a role for diet-induced insulin resistance

Rho kinase (ROCK) isoforms regulate insulin signaling and glucose metabolism negatively or positively in cultured cell lines and skeletal muscle. However, the in vivo function of the ROCK1 isoform in adipose tissue has not been addressed. To determine the specific role of the adipose ROCK1 isoform in the development of insulin resistance and obesity, mice lacking ROCK1 in adipose tissue globally or selectively were studied. Here, we show that insulin's ability to activate IRS-1/PI3K/Akt signaling was greatly enhanced in adipose tissue of ROCK1(-/-) mice compared with wild-type mice. These effects resulted from the inhibitory effect of ROCK1 on insulin receptor action, as evidenced by the fact that IR tyrosine phosphorylation was abolished in ROCK1(-/-) MEF cells when ROCK1 was reexpressed. Consistently, adipose-specific disruption of ROCK1 increased IR tyrosine phosphorylation in adipose tissue and modestly improved sensitivity to insulin in obese mice induced by high-fat feeding. This effect is independent of any changes in adiposity, number or size of adipocytes, and metabolic parameters, including glucose, insulin, leptin, and triglyceride levels, demonstrating a minimal effect of adipose ROCK1 on whole body metabolism. Enzymatic activity of ROCK1 in adipose tissue remained ∼50%, which likely originated from the fraction of stromal vascular cells, suggesting involvement of these cells for adipose metabolic regulation. Moreover, ROCK isoform activities were increased in adipose tissue of diet-induced or genetically obese mice. These data suggest that adipose ROCK1 isoform plays an inhibtory role for the regulation of insulin sensitivity in diet-induced obesity in vivo.