Hu Zhao Ph.D.

Wang, L., Moore, D.C., Huang, J., Wang, Y., Zhao, H., J, D.H.Y., Jackson, C.L., Quesenberry, P.J., Cao, W. and Yang, W. (2021). “SHP2 regulates the development of intestinal epithelium by modifying OSTERIX(+) crypt stem cell self-renewal and proliferation.” Faseb j 35(1): e21106.

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The protein tyrosine phosphatase SHP2, encoded by PTPN11, is ubiquitously expressed and essential for the development and/or maintenance of multiple tissues and organs. SHP2 is involved in gastrointestinal (GI) epithelium development and homeostasis, but the underlying mechanisms remain elusive. While studying SHP2’s role in skeletal development, we made osteoblast-specific SHP2 deficient mice using Osterix (Osx)-Cre as a driver to excise Ptpn11 floxed alleles. Phenotypic characterization of these SHP2 mutants unexpectedly revealed a critical role of SHP2 in GI biology. Mice lacking SHP2 in Osx(+) cells developed a fatal GI pathology with dramatic villus hypoplasia. OSTERIX, an OB-specific zinc finger-containing transcription factor is for the first time found to be expressed in GI crypt cells, and SHP2 expression in the crypt Osx+ cells is critical for self-renewal and proliferation. Further, immunostaining revealed the colocalization of OSTERIX with OLFM4 and LGR5, two bona fide GI stem cell markers, at the crypt cells. Furthermore, OSTERIX expression is found to be associated with GI malignancies. Knockdown of SHP2 expression had no apparent influence on the relative numbers of enterocytes, goblet cells or Paneth cells. Given SHP2’s key regulatory role in OB differentiation, our studies suggest that OSTERIX and SHP2 are indispensable for gut homeostasis, analogous to SOX9’s dual role as a master regulator of cartilage and an important regulator of crypt stem cell biology. Our findings also provide a foundation for new avenues of inquiry into GI stem cell biology and of OSTERIX’s therapeutic and diagnostic potential.

Men, Y., Y. Wang, Y. Yi, D. Jing, W. Luo, B. Shen, W. Stenberg, Y. Chai, W. P. Ge, J. Q. Feng and H. Zhao (2020). “Gli1+ Periodontium Stem Cells Are Regulated by Osteocytes and Occlusal Force.” Dev Cell.

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Teeth are attached to alveolar bone by the periodontal ligament (PDL), which contains stem cells supporting tissue turnover. Here, we identified Gli1+ cells in adult mouse molar PDL as multi-potential stem cells (PDLSCs) giving rise to PDL, alveolar bone, and cementum. They support periodontium tissue turnover and injury repair. Gli1+ PDLSCs are surrounding the neurovascular bundle and more enriched in the apical region. Canonical Wnt signaling is essential for their activation. Alveolar bone osteocytes negatively regulate Gli1+ PDLSCs activity through sclerostin, a Wnt inhibitor. Blockage of sclerostin accelerates the PDLSCs lineage contribution rate in vivo. Sclerostin expression is modulated by physiological occlusal force. Removal of occlusal force upregulates sclerostin and inhibits PDLSCs activation. In summary, Gli1+ cells are the multipotential PDLSCs in vivo. Osteocytes provide negative feedback to PDLSCs and inhibit their activities through sclerostin. Physiological occlusal force indirectly regulates PDLSCs activities by fine-tuning this feedback loop

Wu, J., Y. Tian, L. Han, C. Liu, T. Sun, L. Li, Y. Yu, B. Lamichhane, R. N. D’Souza, S. E. Millar, R. Krumlauf, D. M. Ornitz, J. Q. Feng, O. Klein, H. Zhao, F. Zhang, R. J. Linhardt and X. Wang (2020). “FAM20B-catalyzed glycosaminoglycans control murine tooth number by restricting FGFR2b signaling.” BMC Biol 18(1): 87.

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BACKGROUND: The formation of supernumerary teeth is an excellent model for studying the molecular mechanisms that control stem/progenitor cell homeostasis needed to generate a renewable source of replacement cells and tissues. Although multiple growth factors and transcriptional factors have been associated with supernumerary tooth formation, the regulatory inputs of extracellular matrix in this regenerative process remains poorly understood. RESULTS: In this study, we present evidence that disrupting glycosaminoglycans (GAGs) in the dental epithelium of mice by inactivating FAM20B, a xylose kinase essential for GAG assembly, leads to supernumerary tooth formation in a pattern reminiscent of replacement teeth. The dental epithelial GAGs confine murine tooth number by restricting the homeostasis of Sox2(+) dental epithelial stem/progenitor cells in a non-autonomous manner. FAM20B-catalyzed GAGs regulate the cell fate of dental lamina by restricting FGFR2b signaling at the initial stage of tooth development to maintain a subtle balance between the renewal and differentiation of Sox2(+) cells. At the later cap stage, WNT signaling functions as a relay cue to facilitate the supernumerary tooth formation. CONCLUSIONS: The novel mechanism we have characterized through which GAGs control the tooth number in mice may also be more broadly relevant for potentiating signaling interactions in other tissues during development and tissue homeostasis.

Song, A., W. Dai, M. J. Jang, L. Medrano, Z. Li, H. Zhao, M. Shao, J. Tan, A. Li, T. Ning, M. M. Miller, B. Armstrong, J. M. Huss, Y. Zhu, Y. Liu, V. Gradinaru, X. Wu, L. Jiang, P. E. Scherer and Q. A. Wang (2019). “Low- and high-thermogenic brown adipocyte subpopulations coexist in murine adipose tissue.” J Clin Invest Nov 25. pii: 129167. [Epub ahead of print].

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Brown adipose tissue (BAT), as the main site of adaptive thermogenesis, exerts beneficial metabolic effects on obesity and insulin resistance. BAT has been previously assumed to contain a homogeneous population of brown adipocytes. Utilizing multiple mouse models capable of genetically labeling different cellular populations, as well as single-cell RNA sequencing and 3D tissue profiling, we discovered a new brown adipocyte subpopulation with low thermogenic activity coexisting with the classical high-thermogenic brown adipocytes within the BAT. Compared with the high-thermogenic brown adipocytes, these low-thermogenic brown adipocytes had substantially lower Ucp1 and Adipoq expression, larger lipid droplets, and lower mitochondrial content. Functional analyses showed that, unlike the high-thermogenic brown adipocytes, the low-thermogenic brown adipocytes have markedly lower basal mitochondrial respiration, and they are specialized in fatty acid uptake. Upon changes in environmental temperature, the 2 brown adipocyte subpopulations underwent dynamic interconversions. Cold exposure converted low-thermogenic brown adipocytes into high-thermogenic cells. A thermoneutral environment had the opposite effect. The recruitment of high-thermogenic brown adipocytes by cold stimulation is not affected by high fat diet feeding, but it does substantially decline with age. Our results revealed a high degree of functional heterogeneity of brown adipocytes.

Li, S., Y. Sun, T. Tian, X. Qin, S. Lin, T. Zhang, Q. Zhang, M. Zhou, X. Zhang, Y. Zhou, H. Zhao, B. Zhu and X. Cai (2019). “MicroRNA-214-3p modified tetrahedral framework nucleic acids target survivin to induce tumour cell apoptosis.” Cell Prolif Oct 23:e12708. [Epub ahead of print].

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OBJECTIVES: Due to the instability of microRNAs, the applications of microRNA are currently limited. Thus, we utilized tetrahedral framework nucleic acids and a targeted microRNAs to form a stable nanocomposite to explore whether this nanocomposite can promote apoptosis of tumour cells. MATERIALS AND METHODS: In our study, the survivin gene, which is expressed only in tumour cells and embryonic cells, was selected as the target gene; miRNA-214-3p, which can reduce the expression of survivin, was modified onto tetrahedral framework nucleic acid, thereby producing a reduction in the expression of survivin upon intracellular delivery and eventually leading to tumour cell apoptosis. RESULTS: By comparing the stability of microRNAs with that of microRNA-tetrahedral framework nucleic acid, we proved the superiority of this carrier system. The results of flow cytometry showed that after treated with this complex, the ratio of A549 cells in both late and early period of apoptosis in miRNA-214-3p-tetrahedral framework nucleic acid group had doubled and the cell cycle in the G2-M phase had declined. The decrease in the expression of anti-apoptotic protein and the increase in the expression of pro-apoptotic protein indicate that the ability of this complex to function in cells also makes it attractive as a new targeted therapy for cancer. CONCLUSION: The unique expression of survivin in tumour cells and embryonic cells makes microRNA-tetrahedral framework nucleic acid a new targeted therapy. In addition, due to the functional diversity of microRNAs, this delivery system approach can be applied to a wide variety of fields, such as targeted therapy and tissue regeneration.