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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 the Hippo pathway effectors during embryonic development of the pituitary gland. RNAscope mRNA in situ hybridization using probes against Yap1, Tead1, Tead2, Tead3, and Tead4 on sections of wild type CD1 embryos between 10.5dpc and 17.5dpc. (A–E)Yap1 transcripts are detected in neural tissue, mesenchyme and Rathke's pouch epithelium between 10.5dpc and 13.5dpc (A–C, arrowheads indicating RP expression). Note the dorsal expression bias at 12.5dpc and 13.5dpc and absence of transcripts in the rostral tip (arrows in B,C). Transcripts persist in all tissues at 15.5dpc and 17.5dpc especially in the periluminal region (black arrowhead in D) and epithelium surrounding the third ventricle (white arrowheads in D,E). (F–Y) Expression of Tead1, Tead2, Tead3, and Tead4 encoding TEAD transcription factors. Tead1 and Tead3 transcripts are detectable in all tissues at low levels (F–J,P–T), higher in RP (arrowheads in F,H,P–R). Tead2 is highly expressed in all tissues at 10.5dpc (K), and from 12.5dpc becomes restricted to the ventral diencephalon in neural tissue (L,M) and to the epithelium surrounding the third ventricle (white arrowheads in N,O). Tead2 is strongly expressed in the periluminal epithelium of the anterior pituitary primordium (black arrowheads L–O) but excluded from the rostral tip (arrows L,M). Tead4 transcripts are barely detectable (U–Y). Abbreviations: rp, Rathke's pouch; vd, ventral diencephalon; m, mesenchyme; 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,P–R,U–W: d, dorsal; v, ventral; r, rostral; c, caudal). Axes in (D) applicable to (D,E,I,J,N,O,S,T,X,Y: d, dorsal; v, ventral; ri, right; le, left). Scale bars 200 μm.
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Figure 4: Expression of the Hippo pathway effectors during embryonic development of the pituitary gland. RNAscope mRNA in situ hybridization using probes against Yap1, Tead1, Tead2, Tead3, and Tead4 on sections of wild type CD1 embryos between 10.5dpc and 17.5dpc. (A–E)Yap1 transcripts are detected in neural tissue, mesenchyme and Rathke's pouch epithelium between 10.5dpc and 13.5dpc (A–C, arrowheads indicating RP expression). Note the dorsal expression bias at 12.5dpc and 13.5dpc and absence of transcripts in the rostral tip (arrows in B,C). Transcripts persist in all tissues at 15.5dpc and 17.5dpc especially in the periluminal region (black arrowhead in D) and epithelium surrounding the third ventricle (white arrowheads in D,E). (F–Y) Expression of Tead1, Tead2, Tead3, and Tead4 encoding TEAD transcription factors. Tead1 and Tead3 transcripts are detectable in all tissues at low levels (F–J,P–T), higher in RP (arrowheads in F,H,P–R). Tead2 is highly expressed in all tissues at 10.5dpc (K), and from 12.5dpc becomes restricted to the ventral diencephalon in neural tissue (L,M) and to the epithelium surrounding the third ventricle (white arrowheads in N,O). Tead2 is strongly expressed in the periluminal epithelium of the anterior pituitary primordium (black arrowheads L–O) but excluded from the rostral tip (arrows L,M). Tead4 transcripts are barely detectable (U–Y). Abbreviations: rp, Rathke's pouch; vd, ventral diencephalon; m, mesenchyme; 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,P–R,U–W: d, dorsal; v, ventral; r, rostral; c, caudal). Axes in (D) applicable to (D,E,I,J,N,O,S,T,X,Y: d, dorsal; v, ventral; ri, right; le, left). Scale bars 200 μm.

Mentions: When YAP1 and TAZ are not phosphorylated by LATS kinases they can associate with TEAD transcription factors in the nucleus to promote expression of target genes. We sought to determine the expression patterns of Yap1 and Tead1-Tead4 in the developing pituitary. We were not able to determine the expression of Taz mRNA using this method. Yap1 showed robust expression in Rathke's pouch and surrounding tissues at 10.5dpc (Figure 4A). By 12.5dpc there was strong expression in the dorsal aspect of the pouch in the epithelium (Figure 4B arrowhead), reduced expression in the expanding ventral portion and no expression in the rostral tip (arrow). This pattern was maintained at 13.5dpc and new tissue in the ventral region that is undergoing commitment showed low expression (arrowhead in Figure 4C). At 15.5 and 17.5dpc, Yap1 transcripts remained strong in the intermediate lobe, marginal zone of the anterior lobe and in scattered groups of cells throughout the anterior lobe (Figures 4D,E, black arrowheads). Yap1 was expressed in neural tissue and surrounding mesenchyme at all stages, maintained until 17.5dpc when it was expressed in the posterior lobe, the cell layer surrounding the third ventricle (white arrowheads in Figures 4D,E) and in mesenchyme-derived connective tissue surrounding the gland. From the four Tead genes, Tead2 expression was the strongest (Figures 4K–O). This was reminiscent of the expression pattern of Yap1: strong expression in RP and all surrounding tissues at 10.5dpc (Figure 4K), strong expression in RP epithelium at 12.5dpc and 13.5dpc (Figures 4L,M, arrowheads) but no expression in the rostral tip (Figures 4L,M, arrows) and reduced expression in the ventral pituitary primordium at 13.5dpc (Figure 4M, asterisk). Tead2 expression remained very high at 15.5dpc in the marginal zone (Figure 4N, black arrowhead) and intermediate lobe and in scattered groups of cells throughout the anterior lobe. Levels of expression were reduced but present at 17.5dpc (Figure 4O, black arrowhead). The posterior lobe also expressed high levels of Tead2, as did cells surrounding the third ventricle (Figures 4N,O, white arrowheads). Tead1 and Tead3 were expressed at low levels at all stages examined (Figures 4F-J, P-T) and Tead4 was not expressed (Figures 4V-Y) except for low levels of transcript in RP at 10.5dpc only (Figures 4U,U′ arrowheads).


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 the Hippo pathway effectors during embryonic development of the pituitary gland. RNAscope mRNA in situ hybridization using probes against Yap1, Tead1, Tead2, Tead3, and Tead4 on sections of wild type CD1 embryos between 10.5dpc and 17.5dpc. (A–E)Yap1 transcripts are detected in neural tissue, mesenchyme and Rathke's pouch epithelium between 10.5dpc and 13.5dpc (A–C, arrowheads indicating RP expression). Note the dorsal expression bias at 12.5dpc and 13.5dpc and absence of transcripts in the rostral tip (arrows in B,C). Transcripts persist in all tissues at 15.5dpc and 17.5dpc especially in the periluminal region (black arrowhead in D) and epithelium surrounding the third ventricle (white arrowheads in D,E). (F–Y) Expression of Tead1, Tead2, Tead3, and Tead4 encoding TEAD transcription factors. Tead1 and Tead3 transcripts are detectable in all tissues at low levels (F–J,P–T), higher in RP (arrowheads in F,H,P–R). Tead2 is highly expressed in all tissues at 10.5dpc (K), and from 12.5dpc becomes restricted to the ventral diencephalon in neural tissue (L,M) and to the epithelium surrounding the third ventricle (white arrowheads in N,O). Tead2 is strongly expressed in the periluminal epithelium of the anterior pituitary primordium (black arrowheads L–O) but excluded from the rostral tip (arrows L,M). Tead4 transcripts are barely detectable (U–Y). Abbreviations: rp, Rathke's pouch; vd, ventral diencephalon; m, mesenchyme; 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,P–R,U–W: d, dorsal; v, ventral; r, rostral; c, caudal). Axes in (D) applicable to (D,E,I,J,N,O,S,T,X,Y: d, dorsal; v, ventral; ri, right; le, left). Scale bars 200 μm.
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Figure 4: Expression of the Hippo pathway effectors during embryonic development of the pituitary gland. RNAscope mRNA in situ hybridization using probes against Yap1, Tead1, Tead2, Tead3, and Tead4 on sections of wild type CD1 embryos between 10.5dpc and 17.5dpc. (A–E)Yap1 transcripts are detected in neural tissue, mesenchyme and Rathke's pouch epithelium between 10.5dpc and 13.5dpc (A–C, arrowheads indicating RP expression). Note the dorsal expression bias at 12.5dpc and 13.5dpc and absence of transcripts in the rostral tip (arrows in B,C). Transcripts persist in all tissues at 15.5dpc and 17.5dpc especially in the periluminal region (black arrowhead in D) and epithelium surrounding the third ventricle (white arrowheads in D,E). (F–Y) Expression of Tead1, Tead2, Tead3, and Tead4 encoding TEAD transcription factors. Tead1 and Tead3 transcripts are detectable in all tissues at low levels (F–J,P–T), higher in RP (arrowheads in F,H,P–R). Tead2 is highly expressed in all tissues at 10.5dpc (K), and from 12.5dpc becomes restricted to the ventral diencephalon in neural tissue (L,M) and to the epithelium surrounding the third ventricle (white arrowheads in N,O). Tead2 is strongly expressed in the periluminal epithelium of the anterior pituitary primordium (black arrowheads L–O) but excluded from the rostral tip (arrows L,M). Tead4 transcripts are barely detectable (U–Y). Abbreviations: rp, Rathke's pouch; vd, ventral diencephalon; m, mesenchyme; 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,P–R,U–W: d, dorsal; v, ventral; r, rostral; c, caudal). Axes in (D) applicable to (D,E,I,J,N,O,S,T,X,Y: d, dorsal; v, ventral; ri, right; le, left). Scale bars 200 μm.
Mentions: When YAP1 and TAZ are not phosphorylated by LATS kinases they can associate with TEAD transcription factors in the nucleus to promote expression of target genes. We sought to determine the expression patterns of Yap1 and Tead1-Tead4 in the developing pituitary. We were not able to determine the expression of Taz mRNA using this method. Yap1 showed robust expression in Rathke's pouch and surrounding tissues at 10.5dpc (Figure 4A). By 12.5dpc there was strong expression in the dorsal aspect of the pouch in the epithelium (Figure 4B arrowhead), reduced expression in the expanding ventral portion and no expression in the rostral tip (arrow). This pattern was maintained at 13.5dpc and new tissue in the ventral region that is undergoing commitment showed low expression (arrowhead in Figure 4C). At 15.5 and 17.5dpc, Yap1 transcripts remained strong in the intermediate lobe, marginal zone of the anterior lobe and in scattered groups of cells throughout the anterior lobe (Figures 4D,E, black arrowheads). Yap1 was expressed in neural tissue and surrounding mesenchyme at all stages, maintained until 17.5dpc when it was expressed in the posterior lobe, the cell layer surrounding the third ventricle (white arrowheads in Figures 4D,E) and in mesenchyme-derived connective tissue surrounding the gland. From the four Tead genes, Tead2 expression was the strongest (Figures 4K–O). This was reminiscent of the expression pattern of Yap1: strong expression in RP and all surrounding tissues at 10.5dpc (Figure 4K), strong expression in RP epithelium at 12.5dpc and 13.5dpc (Figures 4L,M, arrowheads) but no expression in the rostral tip (Figures 4L,M, arrows) and reduced expression in the ventral pituitary primordium at 13.5dpc (Figure 4M, asterisk). Tead2 expression remained very high at 15.5dpc in the marginal zone (Figure 4N, black arrowhead) and intermediate lobe and in scattered groups of cells throughout the anterior lobe. Levels of expression were reduced but present at 17.5dpc (Figure 4O, black arrowhead). The posterior lobe also expressed high levels of Tead2, as did cells surrounding the third ventricle (Figures 4N,O, white arrowheads). Tead1 and Tead3 were expressed at low levels at all stages examined (Figures 4F-J, P-T) and Tead4 was not expressed (Figures 4V-Y) except for low levels of transcript in RP at 10.5dpc only (Figures 4U,U′ arrowheads).

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