A florigen-expressing subpopulation of companion cells expresses other small proteins and reveals a nitrogen-sensitive FT repressor.

The precise onset of flowering is crucial to ensure successful plant reproduction. The gene FLOWERING LOCUS T (FT) encodes florigen, a mobile signal produced in leaves that initiates flowering at the shoot apical meristem. In response to seasonal changes, FT is induced in phloem companion cells located in distal leaf regions. Thus far, a detailed molecular characterization of the FT-expressing cells has been lacking. Here, we used bulk nuclei RNA-seq and single nuclei RNA (snRNA)-seq to investigate gene expression in FT-expressing cells and other phloem companion cells. Our bulk nuclei RNA-seq demonstrated that FT-expressing cells in cotyledons and in true leaves differed transcriptionally. Within the true leaves, our snRNA-seq analysis revealed that companion cells with high FT expression form a unique cluster in which many genes involved in ATP biosynthesis are highly upregulated. The cluster also expresses other genes encoding small proteins, including the flowering and stem growth inducer FPF1-LIKE PROTEIN 1 (FLP1) and the anti-florigen BROTHER OF FT AND TFL1 (BFT). In addition, we found that the promoters of FT and the genes co-expressed with FT in the cluster were enriched for the consensus binding motifs of NITRATE-INDUCIBLE GARP-TYPE TRANSCRIPTIONAL REPRESSOR 1 (NIGT1). Overexpression of the paralogous NIGT1.2 and NIGT1.4 repressed FT expression and significantly delayed flowering under nitrogen-rich conditions, consistent with NIGT1s acting as nitrogen-dependent FT repressors. Taken together, our results demonstrate that major FT-expressing cells show a distinct expression profile that suggests that these cells may produce multiple systemic signals to regulate plant growth and development.

The CALR mutations enhance the expression of the immunosuppressive proteins GARP and LAP on peripheral blood lymphocytes through increased binding of activated platelets.

Recently, an antibody which inhibits the glycoprotein A repetitions predominant (GARP)-mediated release of active transforming growth factor beta (TGFß) from the TGFß propeptide latency-associated peptide (LAP) showed preclinical activity in a murine model of the chronic myeloproliferative neoplasms (MPN). Consequently, we investigated the expression of the immunosuppressive molecules LAP and GARP on peripheral blood lymphocytes from 56 MPN patients and 11 healthy donors (HD). We found that lymphocytes from patients with MPN express higher levels of LAP and GARP with no strong differences found between the different MPN diagnoses. The impact of clinical parameters on the expression of LAP and GARP by lymphocytes showed that patients with calreticulin (CALR)mut MPN have increased expression compared with HD and patients with the Januskinase2 (JAK2) mutation. The fraction of lymphocytes bound to activated platelets (aPLT) strongly correlate to LAP and GARP expression suggesting that it is not the lymphocytes themselves but aPLT, which confer the increased expression of GARP and LAP on MPN patient lymphocytes. Notably, no differences in neither platelet counts nor anti-thrombotic therapy was identified between patients with JAK2- and CALRmut patients. Analysis of platelet gene expression failed to identify differences in expression of relevant genes between JAK2- and CALRmut patients.

Binding requirements for latent transforming growth factor Beta2 activation.

Although the mechanism for activation of latent TGFß1 and TGFß3 is understood to involve the binding of the TGFß propeptide (LAP) to both an integrin and an insoluble substrate, the activation of latent TGFß2 has been unclear because the TGFß2 LAP does not have the classical integrin binding sequence found in the other two TGFß isoform LAPs. To assess the potential requirement for covalent linkage with a matrix or cell surface protein for the activation of latent TGFß2, we generated mice in which the TGFß2 Cys residue predicted to be involved in binding was mutated to Ser (Tgfb2C24S). We reasoned that, if covalent interaction with a second molecule is required for latent TGFß2 activation, mutant mice should display a Tgfb2 null (Tgfb2-/-)-like phenotype. Tgfb2C24S mice closely phenocopy Tgfb2-/- mice with death in utero between E18 and P1 and with congenital heart and kidney defects similar to those described for Tgfb2-/- mice. The mutant latent TGFß2 is secreted at levels similar to WT, yet TGFß signaling monitored as nuclear pSmad2 is suppressed. We conclude that, like latent TGFß1, latent TGFß2 activation requires binding to an immobilized matrix or plasma membrane molecule.

"Decoding inflammation: glycoprotein a repetition predominant, microRNA-142-3-p, and metastasis associated lung adenocarcinoma transcript 1: as novel inflammatory biomarkers of inflammatory bowel disease".

BACKGROUND: Inflammatory bowel disease (IBD) is a chronic gastrointestinal (GI) condition comprising Crohn's disease (CD) and ulcerative colitis (UC). The pathogenesis involves immune system dysregulation, with increased Th (T helper cell)17 cells and reduced regulatory T cell (Treg) differentiation. Transforming growth factor-ß (TGF-ß) secretion from Tregs helps control inflammation, and its production is regulated by glycoprotein-A repetition predominant (GARP) protein along with non-coding RNAs (ncRNAs) like microRNA(miR)-142-3p and metastasis associated lung adenocarcinoma transcript 1 (MALAT1) long non-coding RNAs (LncRNAs). This study analyzed their expression in IBD. METHODS: Blood samples were collected from 44 IBD patients, and 22 healthy controls (HC). RNA extraction and circular DNA (cDNA) synthesis were performed. Real-time polymerase chain reaction (RT-PCR) measured gene expression of GARP, MALAT1, and miR-142-3p. Correlations and group differences were statistically analyzed. RESULTS: Compared to controls, GARP was downregulated while MALAT1 and miR-142-3p were upregulated significantly in IBD group. GARP and MALAT1 expressions positively correlated in controls. MALAT1 and miR-142-3p expressions positively correlated in IBD group. MALAT1 was downregulated in aged HC but upregulated with smoking history across groups. No correlations occurred between gene expression and gender, diet, infections, or disease activity scores. CONCLUSIONS: Dysregulation of GARP, MALAT1, and miR-142-3p likely contributes to inflammation in IBD by reducing TGF-ß. MALAT1 is linked to smoking and age-related changes. These genes have potential as diagnostic markers or therapeutic targets for personalized IBD treatment.

A novel GARP humanized mouse model for efficacy assessment of GARP-targeting therapies.

Although breakthroughs have been achieved with immune checkpoint inhibitors (ICI) therapy, some tumors do not respond to those therapies due to primary or acquired resistance. GARP, a type I transmembrane cell surface docking receptor mediating latent transforming growth factor-ß (TGF-ß) and abundantly expressed on regulatory T lymphocytes and platelets, is a potential target to render these tumors responsive to ICI therapy, and enhancing anti-tumor response especially combined with ICI. To facilitate these research efforts, we developed humanized mouse models expressing humanized GARP (hGARP) instead of their mouse counterparts, enabling in vivo assessment of GARP-targeting agents. We created GARP-humanized mice by replacing the mouse Garp gene with its human homolog. Then, comprehensive experiments, including expression analysis, immunophenotyping, functional assessments, and pharmacologic assays, were performed to characterize the mouse model accurately. The Tregs and platelets in the B-hGARP mice (The letter B is the first letter of the company's English name, Biocytogen.) expressed human GARP, without expression of mouse GARP. Similar T, B, NK, DCs, monocytes and macrophages frequencies were identified in the spleen and blood of B-hGARP and WT mice, indicating that the humanization of GARP did not change the distribution of immune cell in these compartments. When combined with anti-PD-1, monoclonal antibodies (mAbs) against GARP/TGF-ß1 complexes demonstrated enhanced in vivo anti-tumor activity compared to monotherapy with either agent. The novel hGARP model serves as a valuable tool for evaluating human GARP-targeting antibodies in immuno-oncology, which may enable preclinical studies to assess and validate new therapeutics targeting GARP. Furthermore, intercrosses of this model with ICI humanized models could facilitate the evaluation of combination therapies.

The GARP family transcription factor MtHHO3 negatively regulates salt tolerance in Medicago truncatula.

High salinity is one of the detrimental environmental factors restricting plant growth and crop production throughout the world. This study demonstrated that the GARP family transcription factor MtHHO3 is involved in response to salt stress and abscisic acid (ABA) signaling in Medicago truncatula. The transcription of MtHHO3 was repressed by salt, osmotic stress, and ABA treatment. The seed germination assay showed that, overexpression of MtHHO3 in Arabidopsis thaliana caused hypersensitivity to salt and osmotic stress, but increased resistance to ABA inhibition. Overexpression of MtHHO3 in M. truncatula resulted in decreased tolerance of salinity, while loss-of-function mutants mthho3-1 and mthho3-2 were more resistant to salt stress compared with wild-type plants. qRT-PCR analyses showed that MtHHO3 downregulated the expression of genes in stress and ABA responsive pathways. We further demonstrated that MtHHO3 repressed the transcription of the pathogenesis-related gene MtPR2 by binding to its promoter. Overall, these results indicate that MtHHO3 negatively regulates salt stress response in plants and deepen our understanding of the role of the GARP subfamily transcription factors in modulating salt stress and ABA signaling.

Geographical distribution of two major quarantine fruit flies (Bactrocera minax Enderlein and Bactrocera dorsalis Hendel) in Sichuan Basin based on four SDMs.

Both Bactrocera minax and Bactrocera dorsalis are phytophagous insects, and their larvae are latent feeders, which cause great damage and economic losses to agriculture production and trade. This study aimed to provide a scientific reference for researching and developing the feasible countermeasures against these two pests. Based on the distribution data of B. minax and B. dorsalis in China, obtained from the Chinese herbaria, investigation and literature. Four niche models (Garp, Bioclim, Domain, and Maxent) were used to analyze the key environmental factors affecting the distribution of both pests and to build prediction models of the potential distribution in Sichuan Basin. Combined with two statistical standards, area under the receiver operating characteristic curve (AUC) and Kappa, the validity of prediction models were analyzed and compared. The results show that: the average AUC values of the four models are all above 0.90, and the average Kappa values are all above 0.75, indicating that the four models are suitable for predicting the potential distribution area of B. minax and B. dorsalis. The annual range of temperature, the mean temperature in the driest quarter, the mean temperature in the warmest quarter, the annual precipitation, and the precipitation in driest month are the key environmental factors affecting the distribution of B. minax, while the mean diurnal temperature range, the mean temperature in the driest quarter, the seasonal temperature variations and the precipitation in driest month affect the potential distribution of B. dorsalis. The suitable areas for B. minax are mainly concentrated in the eastern of Sichuan Basin, while the suitable areas for B. dorsalis are concentrated in the southeastern. Except for the Bioclim model, the highly-suitable area for both pests predicted by the other three models are all greater than 15.94 × 104 km2 and the moderately-suitable areas are greater than 13.57 × 104 km2. In conclusion, the suitable areas for both pests in Sichuan Basin are quite wide. Therefore, the relevant authorities should be given strengthened monitoring of both pests, especially in areas with high incursion rates.

Role of GARP family transcription factors in the regulatory network for nitrogen and phosphorus acquisition.

The GARP (Golden2, ARR-B, Psr1) family proteins with a conserved DNA-binding domain, called the B-motif, are plant-specific transcription factors involved in the regulation of various physiological processes. The GARP family proteins are divided into members that function as monomeric transcription factors, and members that function as transcription factors in the dimeric form, owing to the presence of a coiled-coil dimerization domain. Recent studies revealed that the dimer-forming GARP family members, which are further divided into the PHR1 and NIGT1 subfamilies, play critical roles in the regulation of phosphorus (P) and nitrogen (N) acquisition. In this review, we present a general overview of the GARP family proteins and discuss how several members of the PHR1 and NIGT1 subfamilies are involved in the coordinated acquisition of P and N in response to changes in environmental nutrient conditions, while mainly focusing on the recent findings that enhance our knowledge of the roles of PHR1 and NIGT1 in phosphate starvation signaling and nitrate signaling.

Spatial Distribution of Non-Immune Cells Expressing Glycoprotein A Repetitions Predominant in Human and Murine Metastatic Lymph Nodes.

Several types of cancer spread through the lymphatic system via the sentinel lymph nodes (LNs). Such LN-draining primary tumors, modified by tumor factors, lead to the formation of a metastatic niche associated with an increased number of Foxp3+ regulatory T cells (Tregs). These cells are expected to contribute to the elaboration of an immune-suppressive environment. Activated Tregs express glycoprotein A repetitions predominant (GARP), which binds and presents latent transforming growth factor beta 1 (TGF-ß1) at their surface. GARP is also expressed by other non-immune cell types poorly described in LNs. Here, we mapped GARP expression in non-immune cells in human and mouse metastatic LNs. The mining of available (human and murine) scRNA-Seq datasets revealed GARP expression by blood (BEC)/lymphatic (LEC) endothelial, fibroblastic, and perivascular cells. Consistently, through immunostaining and in situ RNA hybridization approaches, GARP was detected in and around blood and lymphatic vessels, in (αSMA+) fibroblasts, and in perivascular cells associated with an abundant matrix. Strikingly, GARP was detected in LECs forming the subcapsular sinus and high endothelial venules (HEVs), two vascular structures localized at the interface between LNs and the afferent lymphatic and blood vessels. Altogether, we here provide the first distribution maps for GARP in human and murine LNs.

Nuclear Glycoprotein A Repetitions Predominant (GARP) Is a Common Trait of Glioblastoma Stem-like Cells and Correlates with Poor Survival in Glioblastoma Patients.

Glioblastoma (GB) is notoriously resistant to therapy. GB genesis and progression are driven by glioblastoma stem-like cells (GSCs). One goal for improving treatment efficacy and patient outcomes is targeting GSCs. Currently, there are no universal markers for GSCs. Glycoprotein A repetitions predominant (GARP), an anti-inflammatory protein expressed by activated regulatory T cells, was identified as a possible marker for GSCs. This study evaluated GARP for the detection of human GSCs utilizing a multidimensional experimental design that replicated several features of GB: (1) intratumoral heterogeneity, (2) cellular hierarchy (GSCs with varied degrees of self-renewal and differentiation), and (3) longitudinal GSC evolution during GB recurrence (GSCs from patient-matched newly diagnosed and recurrent GB). Our results indicate that GARP is expressed by GSCs across various cellular states and disease stages. GSCs with an increased GARP expression had reduced self-renewal but no alterations in proliferative capacity or differentiation commitment. Rather, GARP correlated inversely with the expression of GFAP and PDGFR-α, markers of astrocyte or oligodendrocyte differentiation. GARP had an abnormal nuclear localization (GARPNU+) in GSCs and was negatively associated with patient survival. The uniformity of GARP/GARPNU+ expression across different types of GSCs suggests a potential use of GARP as a marker to identify GSCs.

Exploring the Binding Affinity of the ARR2 GARP DNA Binding Domain via Comparative Methods.

Plants have evolved signaling mechanisms such as the multi-step phosphorelay (MSP) to respond to different internal and external stimuli. MSP responses often result in gene transcription regulation that is modulated through transcription factors such as B-type Arabidopsis response regulator (ARR) proteins. Among these proteins, ARR2 is a key component that is expressed ubiquitously and is involved in many aspects of plant development. Although it has been noted that B-type ARRs bind to their cognate genes through a DNA-binding domain termed the GARP domain, little is known about the structure and function of this type of DNA-binding domain; thus, how ARRs bind to DNA at a structural level is still poorly understood. In order to understand how the MSP functions in planta, it is crucial to unravel both the kinetics as well as the structural identity of the components involved in such interactions. For this reason, this work focusses on resolving how the GARP domain of ARR2 (GARP2) binds to the promoter region of ARR5, one of its native target genes in cytokinin signaling. We have established that GARP2 specifically binds to the ARR5 promoter with three different bi-molecular interaction systems-qDPI-ELISA, FCS, and MST-and we also determined the KD of this interaction. In addition, structural modeling of the GARP2 domain confirms that GARP2 entails a HTH motif, and that protein-DNA interaction most likely occurs via the α3-helix and the N-terminal arm of this domain since mutations in this region hinder ARR2's ability to activate transcription.

The predicted potential distribution of Aedes albopictus in China under the shared socioeconomic pathway (SSP)1-2.6.

Aedes albopictus (Skuse) (Diptera: Culicidae) is one of the 100 most invasive species in the world and represents a significant threat to public health. The distribution of Ae. albopictus has been expanding rapidly due to increased international trade, population movement, global warming and accelerated urbanization. Consequently, it is very important to know the potential distribution area of Ae. albopictus in advance for early warning and control of its spread and invasion. We randomly selected 282 distribution sites from 27 provincial-level administrative regions in China, and used the GARP and MaxEnt models to analyze and predict the current and future distribution areas of Ae. albopictus in China. The results showed that the current range of Ae. albopictus in China covers most provinces such as Yunnan and Guizhou Provinces, and the distribution of Ae. albopictus in border provinces such as Tibet, Gansu and Jilin Provinces tend to expand westwards. In addition, the potential distribution area of Ae. albopictus in China will continue to expand westwards due to future climate change under the SSP126 climate scenario. Furthermore, the results of environmental factor filtering showed that temperature and precipitation had a large effect on the distribution probability of Ae. albopictus.

GARP on hepatic stellate cells is essential for the development of liver fibrosis.

BACKGROUND & AIMS: Glycoprotein A repetitions predominant (GARP) is a membrane protein that functions as a latent TGF-ß docking molecule. While the immune regulatory properties of GARP on blood cells have been studied, the function of GARP on tissue stromal cells remains unclear. Here, we investigate the role of GARP expressed on hepatic stellate cells (HSCs) in the development of liver fibrosis. METHODS: The function of GARP on HSCs was explored in toxin-induced and metabolic liver fibrosis models, using conditional GARP-deficient mice or a newly generated inducible system for HSC-specific gene ablation. Primary mouse and human HSCs were isolated to evaluate the contribution of GARP to the activation of latent TGF-ß. Moreover, cell contraction of HSCs in the context of TGF-ß activation was tested in a GARP-dependent fashion. RESULTS: Mice lacking GARP in HSCs were protected from developing liver fibrosis. Therapeutically deleting GARP on HSCs alleviated the fibrotic process in established disease. Furthermore, natural killer T cells exacerbated hepatic fibrosis by inducing GARP expression on HSCs through IL-4 production. Mechanistically, GARP facilitated fibrogenesis by activating TGF-ß and enhancing endothelin-1-mediated HSC contraction. Functional GARP was expressed on human HSCs and significantly upregulated in the livers of patients with fibrosis. Lastly, deletion of GARP on HSCs did not augment inflammation or liver damage. CONCLUSIONS: GARP expressed on HSCs drives the development of liver fibrosis via cell contraction-mediated activation of latent TGF-ß. Considering that systemic blockade of TGF-ß has major side effects, we highlight a therapeutic niche provided by GARP and surface-mediated TGF-ß activation. Thus, our findings suggest an important role of GARP on HSCs as a promising target for the treatment of liver fibrosis. IMPACT AND IMPLICATIONS: Liver fibrosis represents a substantial and increasing public health burden globally, for which specific treatments are not available. Glycoprotein A repetitions predominant (GARP) is a membrane protein that functions as a latent TGF-ß docking molecule. Here, we show that GARP expressed on hepatic stellate cells drives the development of liver fibrosis. Our findings suggest GARP as a novel target for the treatment of fibrotic disease.

Selective activation of TGFß signaling by P. gingivalis-mediated upregulation of GARP aggravates esophageal squamous cell carcinoma.

Aberrant TGFß signaling plays critical roles in the progression of multiple cancers; however, the functional mechanism of this signaling network in the infectious milieu of Esophageal Squamous Cell Carcinoma (ESCC) remains largely unknown. In this study, by using global transcriptomic analysis, we found that Porphyromonas gingivalis infection increased TGFß secretion and promoted the activation of TGFß/Smad signaling in cultured cells and in clinical ESCC samples. Furthermore, we demonstrated for the first time that P. gingivalis enhanced the expression of Glycoprotein A repetitions predominant (GARP), thereby activating TGFß/Smad signaling. Moreover, the increased GARP expression and the subsequent TGFß activation was partially dependent on the fimbriae (FimA) of P. gingivalis. Intriguingly, eliminating P. gingivalis, inhibiting TGFß, or silencing GARP led to a decreased phosphorylation of Smad2/3, the central mediator of TGFß signaling, as well as an attenuated malignant phenotype of ESCC cells, indicating that the activation of TGFß signaling could be an adverse prognostic factor of ESCC. Consistently, our clinical data demonstrated that the phosphorylation of Smad2/3 and the expression of GARP were positively correlated to the poor prognosis of ESCC patients. Lastly, using xenograft models, we found that P. gingivalis infection remarkably activated TGFß signaling and subsequently enhanced the tumor growth and lung metastasis. Collectively, our study indicated that TGFß/Smad signaling mediates the oncogenic function of P. gingivalis in ESCC, which is augmented by the expression of GARP. Therefore, targeting either P. gingivalis or GARP-TGFß signaling could be a potential treatment strategy for patients with ESCC.

Role of GARP Vesicle Tethering Complex in Golgi Physiology.

The Golgi associated retrograde protein complex (GARP) is an evolutionarily conserved component of Golgi membrane trafficking machinery that belongs to the Complexes Associated with Tethering Containing Helical Rods (CATCHR) family. Like other multisubunit tethering complexes such as COG, Dsl1, and Exocyst, the GARP is believed to function by tethering and promoting fusion of the endosome-derived small trafficking intermediate. However, even twenty years after its discovery, the exact structure and the functions of GARP are still an enigma. Recent studies revealed novel roles for GARP in Golgi physiology and identified human patients with mutations in GARP subunits. In this review, we summarized our knowledge of the structure of the GARP complex, its protein partners, GARP functions related to Golgi physiology, as well as cellular defects associated with the dysfunction of GARP subunits.

Changes in overwintering ground of small yellow croaker (Larimichthys polyactis) based on MaxEnt and GARP models: A case study of the southern Yellow Sea stock.

Small yellow croaker (Larimichthys polyactis), a commercially essential fish commonly caught in China and South Korea, is now facing a severe decline in resources. The recruitment and surplus of L. polyactis depend selecting a suitable marine environment for overwintering. However, the international overwintering migration habit of L. polyactis limits the investigation of its overwintering environment preferences and suitable grounds. In this study, based on the distribution data of L. polyactis in the southern Yellow Sea in winter from 2010 to 2019 and ocean remote sensing data such as sea bottom temperature (SBT), sea bottom salinity, chlorophyll-a concentration and water depth (Depth), we used the maximum entropy (MaxEnt) and the genetic algorithm for rule-set production (GARP) models to investigate the overwintering grounds of the southern Yellow Sea stock (SYS). The jackknife test was used to assess the importance of various environmental factors. For modelling the overwintering ground distribution of SYS, the area under the curve values of both models ​were higher than 0.9. The overwintering ground was at 32°10' N-33°48' N, 122°30' E-125°00' E. The direction of its distribution was consistent with the Yellow Sea Warm Current in the southern Yellow Sea during the winter. Compared with the suitable overwintering area during 2010-2014, the highly appropriate overwintering area for SYS to overwinter decreased significantly during 2015-2019, showing a trend of moving to the east and north, related to the increase in fishing pressure and strengthening of the Yellow Sea Warm Current in recent years. Depth was the most significant factor for SYS overwintering, followed by SBT. The overwintering ground was at a depth of 40-65 m during the two periods. Additionally, the suitability of overwintering grounds in the coastal waters of south-western South Korea has gradually increased. This study provides a scientific basis for formulating effective strategies to manage L. polyactis resources under the China-South Korea Fisheries Agreement.

Generation and Analysis of hTERT-RPE1 VPS54 Knock-Out and Rescued Cell Lines.

The Golgi-associated retrograde protein (GARP) complex is proposed to tether endosome-derived transport vesicles, but the exact function and mechanism of GARP action are not completely understood. To uncover the GARP function in human cells, we employ CRISPR/Cas9 strategy and knock out (KO) the unique VPS54 subunit of the GARP complex. In this chapter, we describe the detailed method of generating CRISPR/Cas9-mediated VPS54-KO in hTERT-RPE1 cells, rescue of resulting KO cells with stable near-endogenous expression of myc-tagged VPS54, and validation of KO and rescued (KO-R) cells using Western blot and immunofluorescence approaches. This approach is helpful in uncovering new functions of the GARP and other vesicle tethering complexes.

G2-LIKE CAROTENOID REGULATOR (SlGCR) is a positive regulator of lutein biosynthesis in tomato.

Lutein is an oxygen-containing carotenoid synthesized in plant chloroplasts and chromoplasts. It plays an indispensable role in promoting plant growth and maintaining eye health in humans. The rate-limiting step of lutein biosynthesis is catalyzed by the lycopene ε-cyclase enzyme (LCYE). Although great progress has been made in the identification of transcription factors involved in the lutein biosynthetic pathway, many systematic molecular mechanisms remain to be elucidated. Here, using co-expression analysis, we identified a gene, G2-LIKE CAROTENOID REGULATOR (SlGCR), encoding a GARP G2-like transcription factor, as the potential regulator of SlLCYE in tomato. Silencing of SlGCR reduced the expression of carotenoid biosynthetic genes and the accumulation of carotenoids in tomato leaves. By contrast, overexpression of SlGCR in tomato fruit significantly increased the expression of relevant genes and enhanced the accumulation of carotenoids. SlGCR can directly bind to the SlLCYE promoter and activate its expression. In addition, we also discovered that expression of SlGCR was negatively regulated by the master regulator SlRIN, thereby inhibiting lutein synthesis during tomato fruit ripening. Taken together, we identified SlGCR as a novel regulator involved in tomato lutein biosynthesis, elucidated the regulatory mechanism, and provided a potential tool for tomato lutein metabolic engineering. Supplementary Information: The online version contains supplementary material available at 10.1007/s42994-022-00088-z.