Disease relevance of ISL1

• The ganglion cell layer labeled for Isl1, Pax6 and Isl2 [1].

High impact information on ISL1

• These results establish Islet-1 as the earliest marker of developing motor neurons [2].
• The expression of Islet-1 by neural cells is regulated by inductive signals from the floor plate and notochord [2].
• We show that these elements are specifically bound by ISL1 and are essential for enhancer function in transgenic embryos [3].
• Studies with immunohistochemical, in situ hybridization, and retrograde-tracing methods revealed that many dying cells express Islet proteins and Lim-3 mRNA (motoneuron markers) and send their axons to the somatic region of the embryo before cell death [4].
• Whereas Islet-1 is expressed by motor neurons of all cranial nerves, Islet-2 is expressed only in nuclei that contain somatic motor neurons and transiently in a specialized population of contralateral vestibuloacoustic efferent neurons [5].

Biological context of ISL1

• These results suggest that Islet-1 is involved in determining the cell lineages, proliferation, differentiation and maintenance of hormone-secreting functions of pituitary gonadotrophs and thyrotrophs of chick embryo [6].
• The change in Lim-3 immunopositive (Lim-3(+)) cell number was parallel to that of Islet-1, although Lim-3(+) cell were significantly fewer than Islet-1(+) cell numbers from E4.5 to E8.5 (P < 0.05) [7].
• The up-regulation of islet-1 in developing inner ear hair and supporting cells is accompanied by down-regulation of Pax-2 in these cell types [8].
• FGF2 inhibition resulted in reduced ganglion cell differentiation, as visualized by the expression of the ganglion cell-specific RA4 and Islet-1 markers in optic vesicle cultures [9].
• During early organogenesis, Isl-1 is also expressed in several other discrete domains as reported previously [10].

Anatomical context of ISL1

• Although Islet-1 expression in the pituitary gland of early mouse embryo has been previously described, there are no reports concerning the correlation of Islet-1 expression with lineage restrictions in cell types at the later stages of pituitary development [6].
• In the later developing stages, both Islet-1 and Lim-3 immunopositive cells were consistently detected in the follicular and parafollicular pinealocytes throughout the pineal gland [7].
• Islet-1 expression in the developing chicken inner ear [8].
• Islet-1 expression in hair and supporting cells persists until early postnatal stages, when the transcriptional regulator is down-regulated in hair cells [8].
• Islet-1-expressing cells first appeared in the dorsal spinal cord at embryonic days (E) 3-3 [11].

Associations of ISL1 with chemical compounds

• The cellular types expressing Islet-1 included luteinizing-hormone-positive (LH(+)) gonadotrophs and thyroid-stimulating-hormone-positive (TSH(+)) thyrotrophs [6].

Regulatory relationships of ISL1

• We also demonstrate that islet-1 becomes up-regulated in the presumptive sensory epithelia of the inner ear in regions that are defined by the expression domains of BMP4 [8].

Other interactions of ISL1

• Our data is consistent with a role for islet-1 in differentiating inner ear neurons and sensory epithelia cells, perhaps in the specification of cellular subtypes in conjunction with other LIM/homeodomain proteins [8].
• The induced retina displays the typical multilayered cytoarchitecture and expresses late neuronal differentiation markers such as synaptotagmin and islet-1 [12].
• To analyze how motoneurons acquire regional specification along the anterior-posterior (A-P) axis and in the transverse plane, we observed the expression of Cek8, Islet-1, SC1 and low-affinity NGF receptor on ectopic motoneurons induced by implanting a supernumerary notochord or floor plate [13].

Analytical, diagnostic and therapeutic context of ISL1

• Dual immunohistochemistry showed that adrenocorticotrophs, somatotrophs and lactotrophs did not express Islet-1 [6].

References