The relationship between expressions of the laminin gene and RET gene in Hirschsprung's disease

The impact of the recipient intestinal site on the differentiation of transplanted enteric neural crest cells

PURPOSE

It has long been established that the failure of enteric neural crest cells (ENCCs) to colonize the entire gut results in aganglionosis at the distal colon in Hirschsprung disease (HD). However, it is still unclear how the intestinal microenvironment of the distal aganglionic gut differs from that of the proximal ganglionic gut in HD versus normal gut. We have recently succeeded in transplanting ENCC into aganglionic gut in endothelin receptor B (Ednrb) knockout (KO) mice. to advance the development of cell therapy for HD, it is essential to determine if the transplanted ENCCs differentiate normally in aganglionic gut. Therefore, we designed this study to investigate the impact of the environment of the recipient intestinal tract, at various sites of aganglionic gut, on the differentiation of transplanted ENCCs.

METHODS

ENCCs were isolated from Sox10 Venus transgenic (Tg) mouse gut on embryonic day 18.5 (E18.5) and neurospheres (NS) were generated. Then, NS were transplanted into aganglionic KO and wildtype (WT) gut that had been transected just distal to the ENCC wavefront (KO-wf: n = 6, WT: n = 7), and into distal KO gut transected at a site equivalent to that of the WT (KO-d: n = 6) on E12.5. ENCC differentiation was evaluated using whole-mount immunohistochemistry with Tuj-1 (neuronal marker) and GFAP (glial marker) antibodies.

RESULTS

The transplanted ENCCs migrated to form the myenteric and submucosal plexus in all groups. The ratio of the area of Tuj-1-positive cells/GFAP-positive cells in migrated cells in the recipient gut was found to be significantly lower in KO-d compared to KO-wf and WT, while there was no significant difference between KO-wf and WT groups. This suggests that neuronal/glial differentiation was decreased in KO-d compared to that in KO-wf and WT groups.

CONCLUSION

Our study highlights the differences in ENCC differentiation depending on the site of transplantation. To further develop cell therapy for HD, it is important to consider the impact of the recipient intestinal environment on transplanted ENCCs.

37/67-laminin receptor facilitates neural crest cell migration during enteric nervous system development

Enteric nervous system (ENS) development is governed by interactions between neural crest cells (NCC) and the extracellular matrix (ECM). Hirschsprung disease (HSCR) results from incomplete NCC migration and failure to form an appropriate ENS. Prior studies implicate abnormal ECM in NCC migration failure. We performed a comparative microarray of the embryonic distal hindgut of wild-type and EdnrB^NCC-/- mice that model HSCR and identified laminin-β1 as upregulated in EdnrB^NCC-/- colon. We identified decreased expression of 37/67 kDa laminin receptor (LAMR), which binds laminin-β1, in human HSCR myenteric plexus and EdnrB^NCC-/- NCC. Using a combination of in vitro gut slice cultures and ex vivo organ cultures, we determined the mechanistic role of LAMR in NCC migration. We found that enteric NCC express LAMR, which is downregulated in human and murine HSCR. Binding of LAMR by the laminin-β1 analog YIGSR promotes NCC migration. Silencing of LAMR abrogated these effects. Finally, applying YIGSR to E13.5 EdnrB^NCC-/- colon explants resulted in 80%-100% colonization of the hindgut. This study adds LAMR to the large list of receptors through which NCC interact with their environment during ENS development. These results should be used to inform ongoing integrative, regenerative medicine approaches to HSCR.

Decreased expression of β1 integrin in enteric neural crest cells of the endothelin receptor B null mouse model

BACKGROUND

Interactions between enteric neural crest-derived cells (ENCC) and the surrounding intestinal microenvironment, such as the extracellular matrix (ECM), are critical for regulating enteric nervous system (ENS) development. Integrins are the major receptors for ECM molecules, such as laminin, which have been reported to be involved in the pathogenesis of Hirschsprung's disease. In this study, we examined the expression of β1 integrin in the endothelin receptor B (Ednrb) knock out (KO) mouse gut, which presents with an aganglionic colon.

METHODS

A Sox10-Venus-positive Ednrb KO mouse, where ENCC is labeled with fluorescent protein, 'Venus', was created. Sox10-Venus-positive Ednrb wild type (WT) were used as controls. Small intestine, proximal colon and distal colon were dissected on E13.5 and E15.5 and β1 integrin expression of the gut tissue was examined by immunohistochemistry and real time RT-PCR. The cells of the gut dissected on E11.5 were isolated and cultured for 2 days. Venus-positive ENCC were immunostained with β1 integrin and Tuj-1, which is a marker for neurons.

RESULTS

The expression of β1 integrin was not significantly different between KO and WT in all parts of the gut examined. However, the β1 integrin expression in the isolated ENCC was significantly decreased in KO compared to WT. The average threshold area was 42.98 ± 17.47% in KO and 73.53 ± 13.77 in WT (p < 0.001).

CONCLUSIONS

We demonstrated that β1 integrin expression was specifically decreased in ENCC in Ednrb KO mice. Our results suggest that impaired interaction between integrin and its ligands may disturb normal ENS development, resulting in an aganglionic colon.

The effect of laminin-1 on enteric neural crest-derived cell migration in the Hirschsprung's disease mouse model

BACKGROUND/AIM

Laminin-1 regulates neurite outgrowth in various neuronal cells. We have previously demonstrated that laminin-1 promotes enteric neural crest-derived cell (ENCC) migration by using Sox10-VENUS transgenic mice, in which ENCCs are labeled with a green fluorescent protein, Venus. Mice lacking the endothelin-B receptor gene, Ednrb ^-/- mice, are widely used as a model for Hirschsprung's disease (HD). The aim of this study was to investigate the effects of laminin-1on ENCC migration in Sox10-VENUS⁺/Ednrb ^-/- mice, a newly created HD mice model.

METHODS

Fetal guts were dissected on embryonic day 12.5 (E12.5). Specimens were incubated either with, or without laminin-1 for 24 h and images were taken under a stereoscopic microscope. The length from the stomach to the wavefront of ENCC migration (L-E) and the total length of the gut (L-G) were measured. Changes in the ratio of L-E to L-G (L-E/L-G) after 24 h were calculated.

RESULTS

On E12.5, the wavefront of ENCC migration in the HD gut samples was located in the midgut, whereas the wavefront of ENCC in Sox10-VENUS⁺/Ednrb ^+/+ (WT) samples had reached the hindgut. After 24 h, L-E/L-G had increased by 1.49%, from 34.97 to 36.46%, in HD gut and had increased by 1.07%, from 48.08 to 49.15%, in HD with laminin-1, suggesting there was no positive effect of laminin-1 administration on ENCC migration in HD.

CONCLUSIONS

Our results suggest that laminin-1 does not have a positive effect on ENCC migration in HD mice on E12.5, in contrast to the phenomenon seen in normal mice gut specimens, where laminin-1 promotes ENCC migration during the same period. This suggests that there is an impairment in the interaction between ENCC and extracellular environmental factors, which are required for normal development of the enteric nervous system, resulting in an aganglionic colon in HD.

Laminin-1 promotes enteric nervous system development in mouse embryo

BACKGROUND/AIM

Neuronal development is regulated by extracellular environmental factors including nerve growth factor (NGF) and laminin. We have previously demonstrated that laminin-1 promotes neurite outgrowth of dorsal root ganglion cells by modulating NGF and integrin signaling. However, information about their effects on the enteric nervous system (ENS) is limited. Recently, we succeeded in visualizing enteric neural crest-derived cell (ENCC) migration using SOX10-Venus transgenic mice, in which ENCC are labeled with a green fluorescent protein, Venus. In this study, we examine the effects of NGF and laminin-1 in ENCC migration using SOX10-Venus mice gut.

METHODS

Pregnant SOX10-Venus mice were killed on day 12.5 of gestation. The colorectum was dissected from embryos (n = 10) and placed in culture medium including NGF with or without laminin-1 for 12 h. Extension rates of ENCC migration, colorectum and ENCC migration per colorectum were calculated.

RESULTS

Venus positive-ENCC extension rate was significantly higher in the laminin group (n = 5) compared to control (n = 5), 22.84 and 13.96 %, respectively (p < 0.05). The extension rate of the colorectum was not significantly different between the two groups.

CONCLUSIONS

Our results suggest that laminin promotes ENCC migration in mice. This technique allowed us to visualize the effects of extracellular molecules on ENCC migration and it potentially provides us with an insight into the pathophysiology of developmental disorders of the ENS, such as Hirschsprung's disease.