Glutamine synthetase (GS) activity and spatial and temporal patterns of GS expression in the developing chick retina: Relationship with synaptogenesis in the outer plexiform layer

Prada, Francisco A.; Quesada, A.; Dorado, Manuel E.; Chmielewski, C. E.; Prada, Cármen

doi:10.1002/(sici)1098-1136(199803)22:3<221::aid-glia2>3.0.co;2-8

Cited by 42 publications

(16 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At this stage, MG processes terminated and stratified at the outer and inner limiting membranes (OLM, ILM) as well as the synaptic layers of the retina (Fig. 1; see also Bernardos & Raymond, 2006) similar to the arrangement in other species (Ramon y Cajal, 1960; Uga and Smelser, 1973; Robinson and Dreher, 1990; Dreher et al, 1992; Prada et al, 1998; Bernardos and Raymond, 2006). The lateral territories of zebrafish MG increased from the inner to outer retina: ILM, 28.6± 3.6 μm 2 ; IPL, 62.6± 6.4 μm 2 ; OPL, 89.6± 9.1 μm 2 ; and OLM, 120.4± 8.5 μm 2 (Fig.…”

Section: Resultssupporting

confidence: 62%

In VivoDevelopment of Outer Retinal Synapses in the Absence of Glial Contact

et al. 2010

View full text Add to dashboard Cite

Astroglia secrete factors that promote synapse formation and maintenance. In culture, glial contact has also been shown to facilitate synaptogenesis. Here, we examined whether glial contact is important for establishing circuits in vivo by simultaneously monitoring differentiation of glial cells and local synaptogenesis over time. Photoreceptor circuits of the vertebrate retina are particularly suitable for this study because of the relatively simple, laminar organization of their connectivity with their target neurons, horizontal cells and bipolar cells. Also, individual photoreceptor terminals are ensheathed within the outer plexiform layer (OPL) by the processes of one type of glia, Müller glia cells (MGs). We conducted in vivo time-lapse multiphoton imaging of the rapidly developing and relatively transparent zebrafish retina to ascertain the time course of MG development relative to OPL synaptogenesis. The emergence of synaptic triads, indicative of functional photoreceptor circuits, and structural association with glial processes were also examined across ages by electron microscopy. We first show that MG processes form territories that tile within the inner and outer synaptic layers. We then demonstrate that cone photoreceptor synapses are assembled before the elaboration of MG processes in the OPL. Using a targeted cell ablation approach, we also determined whether the maintenance of photoreceptor synapses is perturbed when local MGs are absent. We found that removal of MGs had no appreciable effect on the stability of newly formed cone synapses. Thus, in contrast to other CNS circuits, contact from glia is not necessary for the formation or immediate stabilization of outer retinal synapses.

show abstract

Section: Resultssupporting

confidence: 62%

In VivoDevelopment of Outer Retinal Synapses in the Absence of Glial Contact

et al. 2010

View full text Add to dashboard Cite

show abstract

“…7 22 In an earlier study of developing chick retina, it was concluded that increased GS expression was not related to Müller cell differentiation but coincided with increased synaptic contacts in the OPL. 6 Consistent with this, when we compared the patterns of GS, GLAST, and synaptophysin expression in the present study; GS-and GLAST-IR appeared approximately 3-4 weeks ''behind'' the early events involved in organisation of synaptic vesicles at the presynaptic membrane.…”

Section: Discussionsupporting

confidence: 87%

“…3 GLAST is responsible for transporting extracellular glutamate into Müller cells, where glutamate is converted by glutamine synthetase (GS) to the inactive form, glutamine, which is subsequently transported back to the neurons for glutamate resynthesis (reviewed by Newman and Reichenbach 4 and Danbolt 5 ). Developmental studies suggest a relation between the onset of synaptogenesis and the expression of GS 6 and GLAST, 7 consistent with a role for Müller cells and these proteins in the early establishment of retinal circuitry.…”

mentioning

confidence: 88%

Muller cell expression of glutamate cycle related proteins and anti-apoptotic proteins in early human retinal development

Georges¹,

Cornish²,

Provis³

et al. 2006

British Journal of Ophthalmology

View full text Add to dashboard Cite

Aims: The distribution of glutamate cycle related proteins (glutamine synthetase (GS) and GLAST) and anti-apoptotic proteins (Bcl-2 and Bcl-X) was investigated in Müller cells during early human retinal development, relative to the onset of expression of synaptophysin, a presynaptic vesicle protein.Methods: Using frozen sections of human fetal eyes (13-22 weeks gestation) (n = 10), Bcl-2, Bcl-X, GS, GLAST, and synaptophysin immunoreactivities (IR) were imaged using fluorescence microscopy and plotted as a function of eccentricity from the incipient fovea. Frozen sections of adult human retina (n = 4) were immunolabelled with antibodies to Bcl-2 and Bcl-X. Results: Müller cell immunoreactivity for GS, GLAST, and Bcl-2 was initially detected in the incipient fovea, and then at more peripheral locations with increasing age. Synaptophysin-IR appeared earlier than all other target proteins. Within the synaptophysin-IR region, mature (differentiated) Müller cells expressed both Bcl-2 and Bcl-X-IR from 13 weeks gestation, ahead of GS-IR and GLAST-IR that were first seen at 14 weeks gestation. Additionally, from as early as 13 weeks gestation, ganglion cells and immature neuronal progenitor cells across the entire retina expressed Bcl-2-IR and Bcl-X-IR, respectively. In adult retina, ganglion cells and some bipolar cells expressed Bcl-X but not Bcl-2. Conclusion: Müller cells express Bcl-2 and Bcl-X after synaptogenesis has commenced, but before the onset of GS and GLAST expression, suggesting a protective role for these proteins in Müller cells during the onset of glutamatergic transmission in early human retinal development.

show abstract

“…We have previously demonstrated that these cytoarchitectural structures are correlated with photoreceptor health and integrity (Jablonski and Ervin, 2000); this study further suggests that they may be critical for the proper assembly of outer segments. In addition, other laboratories have demonstrated that proper cell-cell contact between Mü ller cells and retinal neurons regulates the expression of glutamine synthetase by Mü ller cells (Linser and Moscona, 1979;Linser et al, 1982;Vardimon et al, 1991;Prada et al, 1998). While these studies did not determine a causeeffect relationship between the presence of the adherens junction and the expression of glutamine synthetase, they do suggest that a correlation exists between the two aspects.…”

Section: Discussionmentioning

confidence: 94%