RESUMEN
Tyro3, AXL, and MerTK (TAM) receptors are activated in macrophages in response to tissue injury and as such have been proposed as therapeutic targets to promote inflammation resolution during sterile wound healing, including myocardial infarction. Although the role of MerTK in cardioprotection is well characterized, the unique role of the other structurally similar TAMs, and particularly AXL, in clinically relevant models of myocardial ischemia/reperfusion infarction (IRI) is comparatively unknown. Utilizing complementary approaches, validated by flow cytometric analysis of human and murine macrophage subsets and conditional genetic loss and gain of function, we uncover a maladaptive role for myeloid AXL during IRI in the heart. Cross signaling between AXL and TLR4 in cardiac macrophages directed a switch to glycolytic metabolism and secretion of proinflammatory IL-1ß, leading to increased intramyocardial inflammation, adverse ventricular remodeling, and impaired contractile function. AXL functioned independently of cardioprotective MerTK to reduce the efficacy of cardiac repair, but like MerTK, was proteolytically cleaved. Administration of a selective small molecule AXL inhibitor alone improved cardiac healing, which was further enhanced in combination with blockade of MerTK cleavage. These data support further exploration of macrophage TAM receptors as therapeutic targets for myocardial infarction.
Asunto(s)
Macrófagos/metabolismo , Infarto del Miocardio/complicaciones , Infarto del Miocardio/metabolismo , Miocarditis/etiología , Miocarditis/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Tirosina Quinasas Receptoras/metabolismo , Animales , Modelos Animales de Enfermedad , Femenino , Humanos , Inflamasomas/metabolismo , Activación de Macrófagos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Daño por Reperfusión Miocárdica/complicaciones , Daño por Reperfusión Miocárdica/metabolismo , Proteínas Proto-Oncogénicas/deficiencia , Proteínas Proto-Oncogénicas/genética , Receptor Cross-Talk , Proteínas Tirosina Quinasas Receptoras/deficiencia , Proteínas Tirosina Quinasas Receptoras/genética , Infarto del Miocardio con Elevación del ST/metabolismo , Transducción de Señal , Receptor Toll-Like 4/metabolismo , Tirosina Quinasa c-Mer/deficiencia , Tirosina Quinasa c-Mer/genética , Tirosina Quinasa c-Mer/metabolismo , Tirosina Quinasa del Receptor AxlRESUMEN
OBJECTIVE: To test whether the tyrosine kinase Tyro3 affects arthritis. Tyro3, the ligand of growth arrest-specific protein 6 (GAS6) is a receptor tyrosine kinase involved in cell survival. Tyro3 and GAS6 are expressed in the arthritic synovium, and in vitro studies have shown their role in osteoclast differentiation. METHODS: Bone was assessed by micro CT and histomorphometry in Tyro3-deficient (Tyro3(-/-)) and wild-type mice. Arthritis was induced in both genotypes, and Gas6 level was measured by ELISA. Synovitis, synovial hyperplasia, bone erosion, osteoclast activation and osteoclast gene expression were assessed by histomorphometry and reverse transcriptase-PCR, respectively. In vitro osteoclast differentiation assays were performed in Tyro3(-/-) and wild-type mice. Furthermore, effects of Tyro3 and GAS6 on human synovial fibroblast proliferation and osteoclastogenesis were assessed in human cells. RESULTS: Tyro3(-/-) mice had significantly higher bone mass than wild-type littermates. Induction of arthritis increased GAS6 serum levels. Arthritic Tyro3(-/-) mice showed less synovial hyperplasia, osteoclast numbers and bone damage compared with controls. In vivo expression of osteoclast-associated receptor and receptor activator of nuclear factor-κB and in vitro osteoclastogenesis were impaired in Tyro3(-/-) mice. GAS6 also induced synovial fibroblast proliferation and osteoclast differentiation in human cells in Tyro3-dependent manner. CONCLUSIONS: These findings indicate that Tyro3 is a critical signal for synovial hyperplasia, osteoclast differentiation and bone erosion during arthritis. GAS6 and Tyro3 therefore constitute therapeutic targets to inhibit synovial hyperplasia and associated bone erosion.
Asunto(s)
Artritis Experimental/complicaciones , Artritis Reumatoide/complicaciones , Osteoporosis/prevención & control , Proteínas Tirosina Quinasas Receptoras/fisiología , Membrana Sinovial/patología , Animales , Artritis Experimental/enzimología , Artritis Experimental/metabolismo , Artritis Reumatoide/enzimología , Artritis Reumatoide/metabolismo , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/fisiología , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Relación Dosis-Respuesta a Droga , Técnicas de Inactivación de Genes , Humanos , Hiperplasia/etiología , Hiperplasia/prevención & control , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Péptidos y Proteínas de Señalización Intercelular/farmacología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Osteoclastos/efectos de los fármacos , Osteoclastos/patología , Osteoporosis/enzimología , Osteoporosis/etiología , Proteínas Tirosina Quinasas Receptoras/deficiencia , Proteínas Tirosina Quinasas Receptoras/genética , Transducción de Señal/fisiología , Membrana Sinovial/metabolismoRESUMEN
The acquisition of a sexually dimorphic phenotype is a critical event in mammalian development. Hypogonadotropic hypogonadism (HH) results from impaired secretion of GnRH. The patients display with delayed puberty, micropenis and cryptorchidism in the male reflecting gonadotropin insufficiency, and amenorrhea in the female. Kallmann's syndrome (KS) is defined by the association of HH and anosmia or hyposmia (absent smelling sense). Segregation analysis in familial cases has demonstrated diverse inheritance patterns, suggesting the existence of several genes regulating GnRH secretion. The X-linked form of the disease was associated with a genetic defect in the KALI gene located on the Xp22.3 region. KAL1 gene encodes an extracellular matrix glycoprotein anosmin-1, which facilitates neuronal growth and migration. Abnormalities in the migratory processes of the GnRH neurons with the olfactory neurons explain the association of HH with anosmia. Recently, mutations in the FGF recepteur 1 (FGFR1) gene were found in KS with autosomal dominant mode of inheritance. The role of FGFR1 in the function of reproduction requires further investigation. Besides HH with anosmia, there are isolated HH (IHH). No human GnRH mutations have been reported although hypogonadal mice due to a GnRH gene deletion exist. In patients with idiopathic HH and without anosmia an increasing number of GnRH receptor (GnRHR) mutations have been described which represent about 50% of familial cases. The clinical features are highly variable and there is a good relationship between genotype and phenotype. A complete loss of function is associated with the most severe phenotype with resistance to pulsatile GnRH treatment, absence of puberty and cryptorchidism in the male. In contrast, milder loss of function mutations causes incomplete failure of pubertal development. The preponderant role of GnRH in the secretion of LH by the gonadotrophs explains the difference of the phenotype between male and female with partial GnRH resistance. Affected females can have spontaneous telarche and normal breast development while affected males exhibit no pubertal development but normal testis volume, a feature described as "fertile-eunuch". High-dose pulsatile GnRH has been used to induce ovulation. Another gene, called GPR54, responsible for idiopathic HH has been recently described by segregation analysis in two different consanguineous families. The GPR54 gene is an orphan receptor, and its putative ligand is the product of the KISS-1 gene, called metastine. Their roles in the function of reproduction are still unknown.
Asunto(s)
Hormona Liberadora de Gonadotropina/deficiencia , Hipogonadismo/genética , Receptores LHRH/deficiencia , Secuencia de Aminoácidos , Animales , Movimiento Celular , Consanguinidad , Proteínas de la Matriz Extracelular/deficiencia , Proteínas de la Matriz Extracelular/genética , Proteínas de la Matriz Extracelular/fisiología , Femenino , Heterogeneidad Genética , Genotipo , Hormona Liberadora de Gonadotropina/fisiología , Humanos , Hipogonadismo/fisiopatología , Hipotálamo/citología , Hipotálamo/embriología , Síndrome de Kallmann/genética , Síndrome de Kallmann/fisiopatología , Kisspeptinas , Masculino , Ratones , Modelos Biológicos , Datos de Secuencia Molecular , Proteínas del Tejido Nervioso/deficiencia , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/fisiología , Trastornos del Olfato/complicaciones , Trastornos del Olfato/genética , Fenotipo , Mutación Puntual , Proteínas/fisiología , Proteínas Tirosina Quinasas Receptoras/deficiencia , Proteínas Tirosina Quinasas Receptoras/genética , Proteínas Tirosina Quinasas Receptoras/fisiología , Receptor Tipo 1 de Factor de Crecimiento de Fibroblastos , Receptores de Factores de Crecimiento de Fibroblastos/deficiencia , Receptores de Factores de Crecimiento de Fibroblastos/genética , Receptores de Factores de Crecimiento de Fibroblastos/fisiología , Receptores Acoplados a Proteínas G , Receptores de Kisspeptina-1 , Receptores LHRH/química , Receptores LHRH/genética , Receptores LHRH/fisiología , Receptores de Neuropéptido/deficiencia , Receptores de Neuropéptido/genética , Receptores de Neuropéptido/fisiología , Proteínas Supresoras de TumorRESUMEN
Transgenic male mice carrying inactive mutations of the receptor tyrosine kinase c-ros lack the caput epididymidis initial segment and are infertile because sperm volume regulation is compromised. Complementary DNA arrays were used to detect differences in gene expression in the caput epididymidis of heterozygous fertile and homozygous infertile males. The glutamate transporter excitatory amino acid carrier 1 (EAAC1) was expressed in all epididymal regions with high expression in the initial segment and cauda epididymidis. Homozygous knockout mice did not express EAAC1 messenger RNA (mRNA) in the caput but they did express the gene in the corpus and cauda. Immunohistochemical staining for EAAC1 confirmed regional mRNA expression and demonstrated an adluminal location on stereocilia/microvilli of principal cells. The glutamate transporter-associated protein (GTRAP) 3-18 was detected in all epididymal regions independent of genotype, but a highly abundant novel transcript of 4.2 kilobases was found only in the initial segment of heterozygous c-ros mice. High-performance liquid chromatography measurement of glutamate revealed a significantly higher content in the proximal caput of infertile mice than fertile mice, and tissue glutamate content decreased distally in both genotypes. Because glutamate is used as an osmolyte in somatic cells, the lack of EAAC1 reported here may disturb normal osmolyte balance in the proximal epididymal lumen and compromise sperm maturation, in particular the development of sperm volume regulatory mechanisms.