The transforming growth factor beta (TGF-beta) family of growth factors control the development and homeostasis of most tissues in metazoan organisms. Work over the past few years has led to the elucidation of a TGF-beta signal transduction network. This network involves receptor serine/threonine kinases at the cell surface and their substrates, the SMAD proteins, which move into the nucleus, where they activate target gene transcription in association with DNA-binding partners. Distinct repertoires of receptors, SMAD proteins, and DNA-binding partners seemingly underlie, in a cell-specific manner, the multifunctional nature of TGF-beta and related factors. Mutations in these pathways are the cause of various forms of human cancer and developmental disorders.

TGF-beta signal transduction.

In the last 10 years, a large family of secreted signaling molecules has been discovered that appear to mediate many key events in normal growth and development. The family is known as the TGF-p superfamily (Massague 1990), a name taken from the first member of the family to be isolated (transforming growth factor-^l). This name is somewhat misleading, because TGF-p 1 has a large number of effects in different systems (Spom and Roberts 1992). It actually inhibits the proliferation of many different cell lines, and its original "transforming" activity may be due to secondary effects on matrix pro­ duction and synthesis of other growth factors (Moses et al. 1990). The two dozen other members of the TGF-p superfamily have a remarkable range of activities. In Diosophila, a TGF-p-related gene is required for dorsoventral axis formation in early embryos, communication between tissue layers in gut development, and correct proximal distal patterning of adult appendages. In Xenopus, a TGF-p-related gene is expressed specifically at one end of fertilized eggs and may function in early signaling events that lay out the basic body plan. In mammals, TGF-p-related molecules have been found that control sexual development, pituitary hormone production, and the creation of bones and cartilage. The recognition of TGF-p superfamily members in many different organ­ isms and contexts provides one of the major unifying themes in recent molecular studies of animal growth and development. The rough outlines of the TGF-p family were first rec­ ognized in the 1980s. Since that time, a number of ex­ cellent reviews have appeared that summarize the prop­ erties of different family members (Ying 1989; Massague 1990; Lyons et al. 1991; Spom and Roberts 1992). Here, I will focus on four areas that have seen major progress in the last 3 years: structural characterization of the signal­ ing molecule, isolation of new family members, cloning of receptor molecules, and new genetic tests of the func­ tions of these factors in different organisms.

/pdf/the-tgf-beta-superfamily-new-members-new-receptors-and-new-4idj1n7bhx.pdf

The TGF-beta superfamily: new members, new receptors, and new genetic tests of function in different organisms.

Parkinson's disease is characterised by a slow and progressive degeneration of dopaminergic neurons in the substantia nigra. Despite intensive research, the cause of the neuronal loss in Parkinson's disease is poorly understood. Neuroinflammatory mechanisms might contribute to the cascade of events leading to neuronal degeneration. In this Review, we describe the evidence for neuroinflammatory processes from post-mortem and in vivo studies in Parkinson's disease. We further identify the cellular and molecular events associated with neuroinflammation that are involved in the degeneration of dopaminergic neurons in animal models of the disease. Overall, available data support the importance of non-cell-autonomous pathological mechanisms in Parkinson's disease, which are mostly mediated by activated glial and peripheral immune cells. This cellular response to neurodegeneration triggers deleterious events (eg, oxidative stress and cytokine-receptor-mediated apoptosis), which might eventually lead to dopaminergic cell death and hence disease progression. Finally, we highlight possible therapeutic strategies (including immunomodulatory drugs and therapeutic immunisation) aimed at downregulating these inflammatory processes that might be important to slow the progression of Parkinson's disease.

https://www.thelancet.com/pdfs/journals/laneur/PIIS1474442209700626.pdf

Neuroinflammation in Parkinson's disease: a target for neuroprotection?

ALS-Linked SOD1 Mutant G85R Mediates Damage to Astrocytes and Promotes Rapidly Progressive Disease with SOD1-Containing Inclusions

Glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor with restorative effects in a wide variety of rodent and primate models of Parkinson disease, but penetration into brain tissue from either the blood or the cerebro-spinal fluid is limited. Here we delivered GDNF directly into the putamen of five Parkinson patients in a phase 1 safety trial. One catheter needed to be repositioned and there were changes in the magnetic resonance images that disappeared after lowering the concentration of GDNF. After one year, there were no serious clinical side effects, a 39% improvement in the off-medication motor sub-score of the Unified Parkinson's Disease Rating Scale (UPDRS) and a 61% improvement in the activities of daily living sub-score. Medication-induced dyskinesias were reduced by 64% and were not observed off medication during chronic GDNF delivery. Positron emission tomography (PET) scans of [(18)F]dopamine uptake showed a significant 28% increase in putamen dopamine storage after 18 months, suggesting a direct effect of GDNF on dopamine function. This study warrants careful examination of GDNF as a treatment for Parkinson disease.

/pdf/direct-brain-infusion-of-glial-cell-line-derived-43hy24dm0d.pdf

Direct brain infusion of glial cell line–derived neurotrophic factor in Parkinson disease

A potent neurotrophic factor that enhances survival of midbrain dopaminergic neurons was purified and cloned. Glial cell line-derived neurotrophic factor (GDNF) is a glycosylated, disulfide-bonded homodimer that is a distantly related member of the transforming growth factor-beta superfamily. In embryonic midbrain cultures, recombinant human GDNF promoted the survival and morphological differentiation of dopaminergic neurons and increased their high-affinity dopamine uptake. These effects were relatively specific; GDNF did not increase total neuron or astrocyte numbers nor did it increase transmitter uptake by gamma-aminobutyric-containing and serotonergic neurons. GDNF may have utility in the treatment of Parkinson's disease, which is marked by progressive degeneration of midbrain dopaminergic neurons.

https://science.sciencemag.org/content/sci/260/5111/1130.full.pdf

GDNF: a glial cell line-derived neurotrophic factor for midbrain dopaminergic neurons

A novel neurotrophic factor referred to as glial derived neurotrophic factor (GDNF) has been identified and isolated from serum free growth conditioned medium of B49 glioblastoma cells. Rat and human genes encoding GDNF have been cloned and sequenced. A gene encoding GDNF has been subcloned into a vector, and the vector has been used to transform a host cell in order to produce biologically active GDNF in a recombinant DNA process.

Glial cell line-derived neurotrophic factor

Glial derived neurotrophic factor

A novel neurotrophic factor referred to as glial cell line-derived neurotrophic factor (GDNF) has been identified and isolated from serum free growth medium of B49 glioblastoma cells. Rat and human genes encoding GDNF have been cloned and sequenced. A gene encoding GDNF has been subcloned into a vector, and the vector has been used to transform a host cell in order to produce biologically active GDNF in a recombinant DNA process. An implantable device containing recombinant GDNF secreting cells encapsulated in a semipermeable membrane may be used to treat nerve damage in patients suffering from disorders such as Parkinson's disease.

Implantable device containing GDNF secreting cells for treating nerve damage and methods of use

A novel neurotrophic factor referred to as glial cell line-derived neurotrophic factor (GDNF) has been identified and isolated from serum free growth conditioned medium of B49 glioblastoma cells. Rat and human genes encoding GDNF have been cloned and sequenced. A gene encoding GDNF has been subcloned into a vector, and the vector has been used to transform a host cell in order to produce biologically active GDNF in a recombinant DNA process.

Daniel H. Doherty

Papers

GDNF: a glial cell line-derived neurotrophic factor for midbrain dopaminergic neurons

Glial cell line-derived neurotrophic factor

Glial derived neurotrophic factor

Implantable device containing GDNF secreting cells for treating nerve damage and methods of use

Nucleic acids encoding glial cell line-derived neurotrophic factor (GDNF)