Probes for INS

The control of apical dominance involves auxin, strigolactones (SLs), cytokinins (CKs), and sugars, but the mechanistic controls of this regulatory network are not fully understood. Here, we show that brassinosteroid (BR) promotes bud outgrowth in tomato through the direct transcriptional regulation of BRANCHED1 (BRC1) by the BR signaling component BRASSINAZOLE-RESISTANT1 (BZR1). Attenuated responses to the removal of the apical bud, the inhibition of auxin, SLs or gibberellin synthesis, or treatment with CK and sucrose, were observed in bud outgrowth and the levels of BRC1 transcripts in the BR-deficient or bzr1 mutants. Furthermore, the accumulation of BR and the dephosphorylated form of BZR1 were increased by apical bud removal, inhibition of auxin, and SLs synthesis or treatment with CK and sucrose. These responses were decreased in the DELLA-deficient mutant. In addition, CK accumulation was inhibited by auxin and SLs, and decreased in the DELLA-deficient mutant, but it was increased in response to sucrose treatment. CK promoted BR synthesis in axillary buds through the action of the type-B response regulator, RR10. Our results demonstrate that BR signaling integrates multiple pathways that control shoot branching. Local BR signaling in axillary buds is therefore a potential target for shaping plant architecture.

Light plays an important role in determining plant architecture, which greatly influences crop yield. However, the precise mechanisms by which light signaling regulates bud outgrowth remain to be identified. Here, we show that light regulates bud outgrowth via both HY5 and brassinosteroid (BR)-dependent pathways in tomato. Inactivation of the red-light photoreceptor PHYB, or deficiencies in PHYB or the blue-light photoreceptor CRY1a, inhibits bud outgrowth and leads to decreased accumulation of HY5 protein and increased transcript level of BRANCHED1 (BRC1), a central integrator of branching signals. HY5, functioning as a mobile systemic signal from leaves, promotes bud outgrowth by directly suppressing BRC1 transcript and activating the transcript of BR biosynthesis genes within the lateral buds in tomato. Furthermore, BRC1 prevents the accumulation of cytokinin (CK) and gibberellin (GA) by directly inhibiting the transcript of CK synthesis gene LOG4, while increasing the transcript levels of CK and GA degradation genes (CKX7, GA2ox4, and GA2ox5), leading to an arrest of bud outgrowth. Moreover, bud outgrowth occurs predominantly in the day due to the suppression of BRC1 transcript by HY5. These findings demonstrate that light-inducible HY5 acts as a systemic signaling factor in fine-tuning the bud outgrowth of tomato.

In a multi-level ‘deconstruction’ of omental metastases, we previously identified a prognostic matrisome gene expression signature in high-grade serous ovarian cancer (HGSOC) and twelve other malignancies. Here, our aim was to understand how six of these extracellular matrix, ECM, molecules, COL11A1, COMP, FN1, VCAN, CTSB and COL1A1, are up-regulated in cancer. Using biopsies, we identified significant associations between TGFβR activity, Hedgehog signalling and these ECM molecules and studied the associations in mono-, co- and tri-culture. Activated omental fibroblasts produced more matrix than malignant cells, directed by TGFβR and Hedgehog signalling crosstalk. We ‘reconstructed’ omental metastases in tri-cultures of HGSOC cells, omental fibroblasts and adipocytes. This combination was sufficient to generate all six ECM proteins and the matrisome expression signature. TGFβR and Hedgehog inhibitor combinations attenuated fibroblast activation, gel and ECM remodelling in these models. The tri-culture model reproduces key features of omental metastases and allows study of diseased-associated ECM.

Background: Recruitment and proliferation of osteoprogenitors during the reversal-resorption phase, and their differentiation into mature bone-forming osteoblasts is crucial for initiation of bone formation during bone remodeling. This study investigates the osteoprogenitors’ gradual recruitment, proliferation, and differentiation into bone-forming osteoblasts within intracortical remodeling events of healthy adolescent humans. Methods: The study was conducted on cortical bone specimens from 11 healthy adolescent humans. The osteoprogenitor recruitment route and differentiation into osteoblasts were backtracked using immunostainings and in situ hybridizations with osteoblastic markers (CD271, osterix, collage type 1 and 3). The osteoblastic cell populations were defined based on the pore surfaces and their proliferation index (Ki67), density, and number/circumference were estimated in multiplex-immunofluorescence (Ki67, TRAcP, CD34, SMA) stained sections. Results: During the reversal-resorption phase, osteoclasts are intermixed with osteoblastic reversal cells (COL3A1 high CD271 high COL1A1 low Osterix neg ), which are considered to be spatiotemporal osteoprogenitors of bone-forming osteoblasts. Initiation of bone formation requires a critical density of these osteoblastic reversal cells (43±9 cells/mm), which is reached though proliferation (4.4±0.5% proliferative) and even more so through recruitment of osteoprogenitors, but challenged by the ongoing expansion of the canal circumference. These osteoprogenitors most likely originate from osteoblastic bone lining cells and mainly osteoblastic lumen cells, which expand their population though proliferation (4.6±0.3%) and vascular recruitment. These lumen cells resemble canopy cells above trabecular remodeling sites, and like canopy cells they extend above bone-forming osteoblasts where they may rejuvenate the osteoblast population during bone formation. Conclusion: Initiation of bone formation during intracortical remodeling requires a critical density osteoblastic reversal cells, which is reached though proliferation and recruitment of local osteoprogenitors: bone lining cells and osteoblastic lumen cells.