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Expression Analysis of the Hippo Cascade Indicates a Role in Pituitary Stem Cell Development.

Lodge EJ, Russell JP, Patist AL, Francis-West P, Andoniadou CL - Front Physiol (2016)

Bottom Line: We have also carried out immunolocalisation studies to determine when YAP1 and TAZ, the transcriptional effectors of the Hippo pathway, are active.We find that YAP1/TAZ are active in the stem/progenitor cell population throughout development and at postnatal stages, consistent with their role in promoting the stem cell state.Our results demonstrate for the first time the collective expression of major components of the Hippo pathway during normal embryonic and postnatal development of the pituitary gland.

View Article: PubMed Central - PubMed

Affiliation: Craniofacial Development and Stem Cell Biology, Dental Institute, King's College London London, UK.

ABSTRACT
The pituitary gland is a primary endocrine organ that controls major physiological processes. Abnormal development or homeostatic disruptions can lead to human disorders such as hypopituitarism or tumors. Multiple signaling pathways, including WNT, BMP, FGF, and SHH regulate pituitary development but the role of the Hippo-YAP1/TAZ cascade is currently unknown. In multiple tissues, the Hippo kinase cascade underlies neoplasias; it influences organ size through the regulation of proliferation and apoptosis, and has roles in determining stem cell potential. We have used a sensitive mRNA in situ hybridization method (RNAscope) to determine the expression patterns of the Hippo pathway components during mouse pituitary development. We have also carried out immunolocalisation studies to determine when YAP1 and TAZ, the transcriptional effectors of the Hippo pathway, are active. We find that YAP1/TAZ are active in the stem/progenitor cell population throughout development and at postnatal stages, consistent with their role in promoting the stem cell state. Our results demonstrate for the first time the collective expression of major components of the Hippo pathway during normal embryonic and postnatal development of the pituitary gland.

No MeSH data available.


Related in: MedlinePlus

Expression of putative upstream Hippo pathway regulators during pituitary development. RNAscope mRNA in situ hybridization using probes against Dchs1, Fat3 and Fat4 on sections of wild type CD1 embryos between 10.5dpc and 17.5dpc. (A–E)Dchs1 is expressed in mesenchyme surrounding Rathke's pouch and in neural tissue but absent from Rathke's pouch epithelium (A). Expression in mesenchyme and neural tissue persists at 12.5dpc (B) and 13.5dpc (C) where transcripts are also detectable in RP (arrowhead in B). Expression in all pituitary lobes, the hypothalamus and surrounding mesenchyme is detectable at 15.5dpc (D) and 17.5dpc (E). Note the reduced expression of Dchs1 in the epithelium surrounding the third ventricle in (D,E). (F–J)Fat3 is strongly expressed in Rathke's pouch (arrowheads), surrounding mesenchyme, and neural tissue at 10.5dpc (F). Reduced levels are detected in all tissues between 12.5dpc and 17.5dpc. At 12.5dpc there is a dorsal bias in expression in RP (G), more clearly visible at 13.5dpc (arrowheads in H). Strong expression is detected in the epithelium surrounding the third ventricle at 15.5dpc and 17.5dpc (arrowheads in I,J) and in the posterior pituitary (arrow in J). (K–O)Fat4 transcripts are detected in RP at 10.5dpc (arrowheads in K), in surrounding mesenchyme and neural tissue but excluded from the pharyngeal endoderm (arrow in K). Note the very strong expression in the rostral tip of the anterior pituitary (arrowheads in L,M) at 12.5pc and 13.5dpc and in the ventral diencephalon and infundibulum (arrows in L,M), persisting in the posterior lobe (arrows in N,O). Expression is high in surrounding mesenchyme (arrowheads in N). The box in (N) shows the epithelium around the third ventricle displaying low-level expression. The outlines in (D,E,I,J,N,O) surround anterior pituitary tissue derived from Rathke's pouch. Abbreviations: rp, Rathke's pouch; vd, ventral diencephalon; m, mesenchyme; oe, oral ectoderm; pe, pharyngeal endoderm; inf, infundibulum; sph, sphenoid; rt, rostral tip; pl, posterior lobe; al, anterior lobe; il, intermediate lobe; hy, hypothalamus; 3v, third ventricle. Sagittal sections between 10.5dpc and 13.5dpc and frontal between 15.5dpc and 17.5dpc. Axes in (A) applicable to (A–C,F–H,K–M: d, dorsal; v, ventral; r, rostral; c, caudal). Axes in (D) applicable to (D–E,I–J,N–O: d, dorsal; v, ventral; ri, right; le, left). Scale bars 200 μm.
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Figure 2: Expression of putative upstream Hippo pathway regulators during pituitary development. RNAscope mRNA in situ hybridization using probes against Dchs1, Fat3 and Fat4 on sections of wild type CD1 embryos between 10.5dpc and 17.5dpc. (A–E)Dchs1 is expressed in mesenchyme surrounding Rathke's pouch and in neural tissue but absent from Rathke's pouch epithelium (A). Expression in mesenchyme and neural tissue persists at 12.5dpc (B) and 13.5dpc (C) where transcripts are also detectable in RP (arrowhead in B). Expression in all pituitary lobes, the hypothalamus and surrounding mesenchyme is detectable at 15.5dpc (D) and 17.5dpc (E). Note the reduced expression of Dchs1 in the epithelium surrounding the third ventricle in (D,E). (F–J)Fat3 is strongly expressed in Rathke's pouch (arrowheads), surrounding mesenchyme, and neural tissue at 10.5dpc (F). Reduced levels are detected in all tissues between 12.5dpc and 17.5dpc. At 12.5dpc there is a dorsal bias in expression in RP (G), more clearly visible at 13.5dpc (arrowheads in H). Strong expression is detected in the epithelium surrounding the third ventricle at 15.5dpc and 17.5dpc (arrowheads in I,J) and in the posterior pituitary (arrow in J). (K–O)Fat4 transcripts are detected in RP at 10.5dpc (arrowheads in K), in surrounding mesenchyme and neural tissue but excluded from the pharyngeal endoderm (arrow in K). Note the very strong expression in the rostral tip of the anterior pituitary (arrowheads in L,M) at 12.5pc and 13.5dpc and in the ventral diencephalon and infundibulum (arrows in L,M), persisting in the posterior lobe (arrows in N,O). Expression is high in surrounding mesenchyme (arrowheads in N). The box in (N) shows the epithelium around the third ventricle displaying low-level expression. The outlines in (D,E,I,J,N,O) surround anterior pituitary tissue derived from Rathke's pouch. Abbreviations: rp, Rathke's pouch; vd, ventral diencephalon; m, mesenchyme; oe, oral ectoderm; pe, pharyngeal endoderm; inf, infundibulum; sph, sphenoid; rt, rostral tip; pl, posterior lobe; al, anterior lobe; il, intermediate lobe; hy, hypothalamus; 3v, third ventricle. Sagittal sections between 10.5dpc and 13.5dpc and frontal between 15.5dpc and 17.5dpc. Axes in (A) applicable to (A–C,F–H,K–M: d, dorsal; v, ventral; r, rostral; c, caudal). Axes in (D) applicable to (D–E,I–J,N–O: d, dorsal; v, ventral; ri, right; le, left). Scale bars 200 μm.

Mentions: We next sought to characterize the expression of proposed upstream regulators of the Hippo cascade, homologs of Drosophila Ds and Ft, whose protein products act as ligand-receptor pair. We analyzed expression of Dchs1 and Fat4 that have closest homology to Ft and Ds, as well as Fat3, which is detectable in developing pituitary tissue (Karine Rizzoti, personal communication). Previous studies have reported absence of expression of the remaining homologs Fat1, Fat2, and Dchs2 in the pituitary gland (Diez-Roux et al., 2011). At 10.5dpc we did not observe Dchs1 expression in RP epithelium but transcripts were detected in the caudal mesenchyme as well as in the ventral diencephalon (Figure 2A). Expression in RP was observed at 12.5dpc at low levels and persisted until at least 17.5dpc where it was detected both in the anterior and posterior pituitary and in the hypothalamus, with lowest expression in cells lining the third ventricle (Figures 2B–E). At 10.5dpc we observed robust expression of Fat3 in the developing pouch, in ventral diencephalon and caudal mesenchyme (Figure 2F). Expression in RP persisted at lower levels until at least 17.5dpc (Figures 2G–J, arrowheads in Figures 2G,H), where strongest expression was detected in cells lining the third ventricle (arrowheads in Figures 2I,J) as well as in posterior pituitary tissue (arrow in Figure 2J). Fat4 transcripts were present from 10.5dpc throughout RP (arrowheads in Figure 2K) and oral epithelium but excluded from the pharyngeal endoderm (arrow). Strong expression was detected in surrounding mesenchyme. At 12.5dpc very strong expression was detected at the rostral tip (arrowheads in Figure 2L) with low levels of transcripts in RP epithelium. There was also expression in the infundibulum (arrow in Figures 2L,M) and surrounding mesenchyme. Fat4 was still expressed at 17.5dpc in sporadic cells of the anterior and posterior pituitary (arrows in Figures 2N,O) and surrounding mesenchyme (arrowheads in Figure 2N).


Expression Analysis of the Hippo Cascade Indicates a Role in Pituitary Stem Cell Development.

Lodge EJ, Russell JP, Patist AL, Francis-West P, Andoniadou CL - Front Physiol (2016)

Expression of putative upstream Hippo pathway regulators during pituitary development. RNAscope mRNA in situ hybridization using probes against Dchs1, Fat3 and Fat4 on sections of wild type CD1 embryos between 10.5dpc and 17.5dpc. (A–E)Dchs1 is expressed in mesenchyme surrounding Rathke's pouch and in neural tissue but absent from Rathke's pouch epithelium (A). Expression in mesenchyme and neural tissue persists at 12.5dpc (B) and 13.5dpc (C) where transcripts are also detectable in RP (arrowhead in B). Expression in all pituitary lobes, the hypothalamus and surrounding mesenchyme is detectable at 15.5dpc (D) and 17.5dpc (E). Note the reduced expression of Dchs1 in the epithelium surrounding the third ventricle in (D,E). (F–J)Fat3 is strongly expressed in Rathke's pouch (arrowheads), surrounding mesenchyme, and neural tissue at 10.5dpc (F). Reduced levels are detected in all tissues between 12.5dpc and 17.5dpc. At 12.5dpc there is a dorsal bias in expression in RP (G), more clearly visible at 13.5dpc (arrowheads in H). Strong expression is detected in the epithelium surrounding the third ventricle at 15.5dpc and 17.5dpc (arrowheads in I,J) and in the posterior pituitary (arrow in J). (K–O)Fat4 transcripts are detected in RP at 10.5dpc (arrowheads in K), in surrounding mesenchyme and neural tissue but excluded from the pharyngeal endoderm (arrow in K). Note the very strong expression in the rostral tip of the anterior pituitary (arrowheads in L,M) at 12.5pc and 13.5dpc and in the ventral diencephalon and infundibulum (arrows in L,M), persisting in the posterior lobe (arrows in N,O). Expression is high in surrounding mesenchyme (arrowheads in N). The box in (N) shows the epithelium around the third ventricle displaying low-level expression. The outlines in (D,E,I,J,N,O) surround anterior pituitary tissue derived from Rathke's pouch. Abbreviations: rp, Rathke's pouch; vd, ventral diencephalon; m, mesenchyme; oe, oral ectoderm; pe, pharyngeal endoderm; inf, infundibulum; sph, sphenoid; rt, rostral tip; pl, posterior lobe; al, anterior lobe; il, intermediate lobe; hy, hypothalamus; 3v, third ventricle. Sagittal sections between 10.5dpc and 13.5dpc and frontal between 15.5dpc and 17.5dpc. Axes in (A) applicable to (A–C,F–H,K–M: d, dorsal; v, ventral; r, rostral; c, caudal). Axes in (D) applicable to (D–E,I–J,N–O: d, dorsal; v, ventral; ri, right; le, left). Scale bars 200 μm.
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Figure 2: Expression of putative upstream Hippo pathway regulators during pituitary development. RNAscope mRNA in situ hybridization using probes against Dchs1, Fat3 and Fat4 on sections of wild type CD1 embryos between 10.5dpc and 17.5dpc. (A–E)Dchs1 is expressed in mesenchyme surrounding Rathke's pouch and in neural tissue but absent from Rathke's pouch epithelium (A). Expression in mesenchyme and neural tissue persists at 12.5dpc (B) and 13.5dpc (C) where transcripts are also detectable in RP (arrowhead in B). Expression in all pituitary lobes, the hypothalamus and surrounding mesenchyme is detectable at 15.5dpc (D) and 17.5dpc (E). Note the reduced expression of Dchs1 in the epithelium surrounding the third ventricle in (D,E). (F–J)Fat3 is strongly expressed in Rathke's pouch (arrowheads), surrounding mesenchyme, and neural tissue at 10.5dpc (F). Reduced levels are detected in all tissues between 12.5dpc and 17.5dpc. At 12.5dpc there is a dorsal bias in expression in RP (G), more clearly visible at 13.5dpc (arrowheads in H). Strong expression is detected in the epithelium surrounding the third ventricle at 15.5dpc and 17.5dpc (arrowheads in I,J) and in the posterior pituitary (arrow in J). (K–O)Fat4 transcripts are detected in RP at 10.5dpc (arrowheads in K), in surrounding mesenchyme and neural tissue but excluded from the pharyngeal endoderm (arrow in K). Note the very strong expression in the rostral tip of the anterior pituitary (arrowheads in L,M) at 12.5pc and 13.5dpc and in the ventral diencephalon and infundibulum (arrows in L,M), persisting in the posterior lobe (arrows in N,O). Expression is high in surrounding mesenchyme (arrowheads in N). The box in (N) shows the epithelium around the third ventricle displaying low-level expression. The outlines in (D,E,I,J,N,O) surround anterior pituitary tissue derived from Rathke's pouch. Abbreviations: rp, Rathke's pouch; vd, ventral diencephalon; m, mesenchyme; oe, oral ectoderm; pe, pharyngeal endoderm; inf, infundibulum; sph, sphenoid; rt, rostral tip; pl, posterior lobe; al, anterior lobe; il, intermediate lobe; hy, hypothalamus; 3v, third ventricle. Sagittal sections between 10.5dpc and 13.5dpc and frontal between 15.5dpc and 17.5dpc. Axes in (A) applicable to (A–C,F–H,K–M: d, dorsal; v, ventral; r, rostral; c, caudal). Axes in (D) applicable to (D–E,I–J,N–O: d, dorsal; v, ventral; ri, right; le, left). Scale bars 200 μm.
Mentions: We next sought to characterize the expression of proposed upstream regulators of the Hippo cascade, homologs of Drosophila Ds and Ft, whose protein products act as ligand-receptor pair. We analyzed expression of Dchs1 and Fat4 that have closest homology to Ft and Ds, as well as Fat3, which is detectable in developing pituitary tissue (Karine Rizzoti, personal communication). Previous studies have reported absence of expression of the remaining homologs Fat1, Fat2, and Dchs2 in the pituitary gland (Diez-Roux et al., 2011). At 10.5dpc we did not observe Dchs1 expression in RP epithelium but transcripts were detected in the caudal mesenchyme as well as in the ventral diencephalon (Figure 2A). Expression in RP was observed at 12.5dpc at low levels and persisted until at least 17.5dpc where it was detected both in the anterior and posterior pituitary and in the hypothalamus, with lowest expression in cells lining the third ventricle (Figures 2B–E). At 10.5dpc we observed robust expression of Fat3 in the developing pouch, in ventral diencephalon and caudal mesenchyme (Figure 2F). Expression in RP persisted at lower levels until at least 17.5dpc (Figures 2G–J, arrowheads in Figures 2G,H), where strongest expression was detected in cells lining the third ventricle (arrowheads in Figures 2I,J) as well as in posterior pituitary tissue (arrow in Figure 2J). Fat4 transcripts were present from 10.5dpc throughout RP (arrowheads in Figure 2K) and oral epithelium but excluded from the pharyngeal endoderm (arrow). Strong expression was detected in surrounding mesenchyme. At 12.5dpc very strong expression was detected at the rostral tip (arrowheads in Figure 2L) with low levels of transcripts in RP epithelium. There was also expression in the infundibulum (arrow in Figures 2L,M) and surrounding mesenchyme. Fat4 was still expressed at 17.5dpc in sporadic cells of the anterior and posterior pituitary (arrows in Figures 2N,O) and surrounding mesenchyme (arrowheads in Figure 2N).

Bottom Line: We have also carried out immunolocalisation studies to determine when YAP1 and TAZ, the transcriptional effectors of the Hippo pathway, are active.We find that YAP1/TAZ are active in the stem/progenitor cell population throughout development and at postnatal stages, consistent with their role in promoting the stem cell state.Our results demonstrate for the first time the collective expression of major components of the Hippo pathway during normal embryonic and postnatal development of the pituitary gland.

View Article: PubMed Central - PubMed

Affiliation: Craniofacial Development and Stem Cell Biology, Dental Institute, King's College London London, UK.

ABSTRACT
The pituitary gland is a primary endocrine organ that controls major physiological processes. Abnormal development or homeostatic disruptions can lead to human disorders such as hypopituitarism or tumors. Multiple signaling pathways, including WNT, BMP, FGF, and SHH regulate pituitary development but the role of the Hippo-YAP1/TAZ cascade is currently unknown. In multiple tissues, the Hippo kinase cascade underlies neoplasias; it influences organ size through the regulation of proliferation and apoptosis, and has roles in determining stem cell potential. We have used a sensitive mRNA in situ hybridization method (RNAscope) to determine the expression patterns of the Hippo pathway components during mouse pituitary development. We have also carried out immunolocalisation studies to determine when YAP1 and TAZ, the transcriptional effectors of the Hippo pathway, are active. We find that YAP1/TAZ are active in the stem/progenitor cell population throughout development and at postnatal stages, consistent with their role in promoting the stem cell state. Our results demonstrate for the first time the collective expression of major components of the Hippo pathway during normal embryonic and postnatal development of the pituitary gland.

No MeSH data available.


Related in: MedlinePlus