Peripheral expression and biological activities of GDNF, a new neurotrophic factor for avian and mammalian peripheral neurons.

Abstract

Abstract. Glial cell line-derived neurotrophic factor (GDNF) is a neurotrophic polypeptide, distantly related to transforming growth factor- , originally isolated by virtue of its ability to induce dopamine uptake and cell survival in cultures of embryonic ventral midbrain dopaminergic neurons, and more recently shown to be a potent neurotrophic factor for motorneurons. The biological activities and distribution of this molecule outside the central nervous system are presently unknown. We report here on the mRNA expression, biological activities and initial receptor binding characterization of GDNF and a shorter spliced variant termed GDNF[3 in different organs and peripheral neurons of the developing rat. Both GDNF mRNA forms were found to be most highly expressed in developing skin, whisker pad, kidney, stomach and testis. Lower expression was also detected in developing skeletal muscle, ovary, lung, and adrenal gland. Developing spinal cord, superior cervical ganglion (SCG) and dorsal root ganglion (DRG) also expressed low levels of GDNF mRNA. Two days after nerve transection, GDNF mRNA levels increased dramatically in the sciatic nerve. Overall, GDNF mRNA expression was significantly higher in peripheral organs than in neuronal tissues. Expression of either GDNF mRNA isoform in insect cells resulted in the production of indistinguishable mature GDNF polypeptides. Purified recombinant GDNF promoted neurite outgrowth and survival of embryonic chick sympathetic neurons. GDNF produced robust bundle-like, fasciculated outgrowth from chick sympathetic ganglion explants. Although GDNF displayed only low activity on survival of newborn rat SCG neurons, this protein was found to increase the expression of vasoactive intestinal peptide and preprotachykinin-A mRNAs in cultured SCG neurons. GDNF also promoted survival of about half of the neurons in embryonic chick nodose ganglion and a small subpopulation of embryonic sensory neurons in chick dorsal root and rat trigeminal ganglia. Embryonic chick sympathetic neurons expressed receptors for GDNF with Kd 1-5 × 10 -9 M, as measured by saturation and displacement binding assays. Our findings indicate GDNF is a new neurotrophic factor for developing peripheral neurons and suggest possible non-neuronal roles for GDNF in the developing reproductive system. T HE development and maintenance of the vertebrate nervous system requires the activity of a range of polypeptides known as neurotrophic factors. These molecules have been shown to control the generation, survival, differentiation and regeneration of neurons in the peripheral and central nervous systems (Barde, 1989;Thoenen, 1991). They include members of the neurotrophin family, including NGF and related molecules (Thoenen, 1991: Persson andIb~ifiez, 1993), members of the neurokine family, such as ciliary neurotrophic factor (CNTF), 1

Gdnf signaling pathways within the mammalian spermatogonial stem cell niche

“…Our understanding of the mammalian spermatogonial stem cell niche has recently greatly progressed with the discovery that glial cell line-derived neurotrophic factor (Gdnf), a neurotropic factor secreted by glial cells in the brain, is also expressed in other organs during development, including ovary and testis Hellmich et al, 1996;Trupp et al, 1995;Golden et al, 1999). Gdnf, secreted by Sertoli cells after birth, is so far the only known paracrine factor in the testis specifically responsible for the maintenance and selfrenewal of SSCs in vivo and in vitro (Meng et al, 2000;Kubota et al, 2004b;Hofmann et al, 2005b).…”

Glial Cell Line-Derived Neurotrophic Factor Alters Axon Schwann Cell Units and Promotes Myelination in Unmyelinated Nerve Fibers

“…Glial cell line-derived neurotrophic factor (GDNF), a member of the transforming growth factor-␤ superfamily, was initially isolated on the basis of its potent trophic effects on midbrain dopaminergic neurons in vitro (Lin et al, 1993, and subsequently was shown to be a potent trophic factor for a subset of sensory neurons as well as for sympathetic and parasympathetic neurons (Buj-Bello et al, 1995;Ebendal et al, 1995;Oppenheim et al, 1995;Trupp et al, 1995;Maxwell et al, 1996;Matheson et al, 1997;Molliver et al, 1997;Bennett et al, 1998). Early in development, all small dorsal root ganglion (DRG) neurons require nerve growth factor (NGF) for survival and express its receptors, trkA and p75.…”

“…GDNF mRNA is abundant in the epidermis (Trupp et al, 1995;Botchkareva et al, 2000), and a subset of epidermal nociceptive fibers is dependent on GDNF (Molliver et al, 1997). In peripheral nerves, Schwann cells express mRNA for GDNF and are also presumed to be a source of GDNF for peripheral neurons (Springer et al, 1994;Choi-Lundberg and Bohn, 1995;Ohi et al, 1997).…”

“…In peripheral nerves, Schwann cells express mRNA for GDNF and are also presumed to be a source of GDNF for peripheral neurons (Springer et al, 1994;Choi-Lundberg and Bohn, 1995;Ohi et al, 1997). In response to nerve transection, GDNF mRNA expression in Schwann cells in sciatic nerves and in DRGs rises dramatically, a finding that implicates GDNF in peripheralnerve regeneration (Trupp et al, 1995;Hammarberg et al, 1996;Hoke et al, 2000Hoke et al, , 2002. GDNF mRNA expression is also increased in an experimental model of motor neuropathy in rats (Saita et al, 1997), in various human neuropathies (Yamamoto et al, 1997), and in traumatized human nerves (Bär et al, 1998).…”

Characterization of Two Distinct Monoclonal Antibodies Specific for Glial Cell Line‐Derived Neurotrophic Factor

“…Also, injured adult MNs responded to GDNF following axotomy in the facial nucleus of adult rats . In the PNS, GDNF promoted the survival and neurite outgrowth of sympathetic neurons, parasympathetic ciliary ganglion neurons, and sensory dorsal root ganglion neurons (Trupp et a!., 1995;Ebendal et a!., 1995).…”