The RTF-Compass: Navigating the Trade-Off Between Thermogenic Potential and Ferroptotic Stress in Adipocytes

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript proposes Redox-Thermogenesis-Ferroptosis Compass (RTF-Compass) as a framework to describe the contributions of adipose ferroptosis resistance capacity (FRC), ferroptosis signaling intensity (FSI) and Hif1a-dependent hypoxic tone to the resultant cytotoxic state or thermogenic state of adipose tissue under metabolic or pharmacologic perturbations. The authors conclude that biomarkers of FRC/FSI might provide valuable information for precision redox medicine to combat obesity via enhanced thermogenesis. The RTF-Compass concept is properly described in the manuscript, and potential challenges (e.g., tissue heterogeneity) are discussed. However, the manuscript could be improved by addressing the questions below.

1. Antioxidant and pro-oxidant drives are unlikely to influence thermogenesis if there isn’t flux through the TCA cycle. Is the RTF-compass meant to identify appropriate combination therapies for drugs that enhance oxidative phosphorylation?
2. Do reactive oxygen species that promote or suppress thermogenesis come from the same compartment/source?
3. Is there a distinction between oxidative stress and ferroptosis signaling intensity? Oxidative stress could affect thermogenesis and cause non-ferroptotic cell-death, which diminishes the importance of iron levels.
4. NDAPH typo in Fig. 1.

Author Response

Reviewer 1

Major comments

This manuscript proposes Redox-Thermogenesis-Ferroptosis Compass (RTF-Compass) as a framework to describe the contributions of adipose ferroptosis resistance capacity (FRC), ferroptosis signaling intensity (FSI) and Hif1a-dependent hypoxic tone to the resultant cytotoxic state or thermogenic state of adipose tissue under metabolic or pharmacologic perturbations. The authors conclude that biomarkers of FRC/FSI might provide valuable information for precision redox medicine to combat obesity via enhanced thermogenesis. The RTF-Compass concept is properly described in the manuscript, and potential challenges (e.g., tissue heterogeneity) are discussed. However, the manuscript could be improved by addressing the questions below.

Comment 1: Antioxidant and pro-oxidant drives are unlikely to influence thermogenesis if there isn't flux through the TCA cycle. Is the RTF-compass meant to identify appropriate combination therapies for drugs that enhance oxidative phosphorylation?

Response: We appreciate this crucial conceptual clarification. We fully agree that antioxidant and pro-oxidant tones become functionally relevant for thermogenesis only when the TCA cycle and electron transport chain are actively engaged. In the revised manuscript, we have explicitly stated that the RTF-Compass is designed to operate in thermogenically active or activatable depots. In these states, increased substrate flux generates the ROS and lipid-peroxide tone captured by the Ferroptosis Signaling Intensity (FSI). Consequently, the framework is specifically intended to guide combination strategies—pairing agents that enhance oxidative flux (e.g., β-adrenergic agonists or mitochondrial biogenesis inducers) with modulators of Ferroptosis Resistance Capacity (FRC) and hypoxic tone. (Revised text: Lines 58-64)

Comment 2: Do reactive oxygen species that promote or suppress thermogenesis come from the same compartment/source?

Response: Thank you for this insightful question. We agree that the compartmentalization of ROS is a critical determinant of their functional outcome. While mitochondrial ROS are canonical signals for UCP1-dependent thermogenesis, ROS from extra-mitochondrial sources (e.g., NOX4) or chronic mitochondrial overload are often linked to cytotoxicity. In the revised text, we clarify that while these ROS species originate from overlapping but distinct sources, the RTF-Compass integrates them into a single functional readout—the FSI—which reflects the net lipid-peroxidation-encoded output relevant to cell fate. (Revised text: Lines 88-94)

Comment 3: Is there a distinction between oxidative stress and ferroptosis signaling intensity? Oxidative stress could affect thermogenesis and cause non-ferroptotic cell-death, which diminishes the importance of iron levels.

Response: We fully agree that "oxidative stress" is a broader concept than ferroptosis. To address this, we have refined our terminology to clearly distinguish between the two:

1. Oxidative Stress: Broadly encompasses redox imbalances that may trigger non-ferroptotic injury.
2. Ferroptosis Signaling Intensity (FSI): Specifically refers to the iron-coupled, phospholipid-peroxidation tone that encodes both thermogenic signaling and ferroptotic liability. This distinction emphasizes that FSI is a specific subset of oxidative pressure that is mechanistically coupled to iron availability and lipid peroxidation. (Revised text: Lines 169-175)

Comment 4: NDAPH typo in Fig. 1.

Response: We apologize for the oversight. We have corrected the label to "NADPH" in Figure 1.

Reviewer 2 Report

Comments and Suggestions for Authors

In the following review, Minghao Fu et al. propose the Redox–Thermogenesis–Ferroptosis Compass (RTF-Compass) as a framework that maps adipose depots within a space defined by ferroptosis resistance capacity (FRC), ferroptosis signalling intensity (FSI) and HIF-1α-dependent hypoxic tone.

Likewise, the authors use this model to reinterpret genetic, nutritional and pharmacological studies as state-dependent vectors that move depots through FRC–FSI–HIF space and to outline principles for precision redox medicine.

 

Major points

1. In section 3: HIF-1α as an Oxygen-Sensing Rheostat in Thermogenic Adipose Tissue, the authors should add a paragraph linking changes in HIF-1α expression, UCP-1 expression, GLUTs, and lactate in cancer. Several authors have recently demonstrated that WAT undergoes a browning process toward BAT/beige in the presence of certain tumors (such as breast or renal cancer). This modified adipose tissue promotes tumor development, for example, by stimulating angiogenesis. The authors should add a paragraph in section 3 that addresses these findings.

 

2. Related to the previous point, in Table 1 the authors should add a new section taking into account the interaction between adipose tissue and a nearby tumor, and how this interaction leads, among other things, to browning of the surrounding WAT (waxy-adipose tissue).

Author Response

Reviewer 2.

In the following review, Minghao Fu et al. propose the Redox–Thermogenesis–Ferroptosis Compass (RTF-Compass) as a framework that maps adipose depots within a space defined by ferroptosis resistance capacity (FRC), ferroptosis signalling intensity (FSI) and HIF-1α-dependent hypoxic tone.

Likewise, the authors use this model to reinterpret genetic, nutritional and pharmacological studies as state-dependent vectors that move depots through FRC–FSI–HIF space and to outline principles for precision redox medicine.

Major points

In section 3: HIF-1α as an Oxygen-Sensing Rheostat in Thermogenic Adipose Tissue, the authors should add a paragraph linking changes in HIF-1α expression, UCP-1 expression, GLUTs, and lactate in cancer. Several authors have recently demonstrated that WAT undergoes a browning process toward BAT/beige in the presence of certain tumors (such as breast or renal cancer). This modified adipose tissue promotes tumor development, for example, by stimulating angiogenesis. The authors should add a paragraph in section 3 that addresses these findings.

Comment 1: In section 3, the authors should add a paragraph linking changes in HIF-1α, UCP1, GLUTs, and lactate in cancer. WAT undergoes browning in the presence of certain tumors, promoting tumor development.

Response: We thank the reviewer for this excellent suggestion, which broadens the pathophysiological relevance of our model. We have added a dedicated paragraph to Section 3 discussing "Cancer-Associated Adipose Remodeling." We highlight that while tumor-adjacent WAT can acquire beige features (e.g., UCP1 induction), the tumor-driven metabolic pressure (high HIF-1α, lactate, and VEGF) often decouples these markers from beneficial thermogenesis, instead supporting tumor progression. This phenomenon aligns perfectly with the RTF-Compass concept of context-dependent vectors. (Revised text: Lines 301-313)

Comment 2: Related to the previous point, in Table 1 the authors should add a new section taking into account the interaction between adipose tissue and a nearby tumor.

Response: We agree that the tumor-adipose interaction warrants explicit representation. We have updated Table 1 to include a new row: "Tumor-adipose crosstalk (peritumoral niche)." This addition summarizes how chronic hypoxic/glycolytic pressure in the peritumoral niche drives a unique "browning" phenotype that supports tumor growth rather than systemic energy expenditure

Reviewer 3 Report

Comments and Suggestions for Authors

Adipose tissue thermogenesis can mitigate obesity and metabolic disease but, when chronically activated, increases oxidative and lipid-peroxidation stress that predisposes cells to ferroptotic death. This review explains why similar interventions can either enhance thermogenesis or cause tissue failure, the Redox–Thermogenesis–Ferroptosis Compass integrates ferroptosis resistance capacity, ferroptosis signalling intensity and HIF-1α-dependent hypoxic tone into a unified framework. Within this space, thermogenic output follows a hormetic, inverted-U trajectory within a Thermogenic Ferroptosis Window, reframing prior genetic, nutritional and pharmacological studies and guiding precision redox medicine.

Overall, this paper is very well written and clearly explains the subtleties of the TFW very well. One comment that I have is that the section 2.3.2 does not flow smoothly. It doesn’t seem to specify that it refers to Fig. 2.

Another comment is that “Compass” may not be the best word. Compass indicates direction, whereas the TFW is coordinates.

Author Response

Adipose tissue thermogenesis can mitigate obesity and metabolic disease but, when chronically activated, increases oxidative and lipid-peroxidation stress that predisposes cells to ferroptotic death. This review explains why similar interventions can either enhance thermogenesis or cause tissue failure, the Redox–Thermogenesis–Ferroptosis Compass integrates ferroptosis resistance capacity, ferroptosis signalling intensity and HIF-1α-dependent hypoxic tone into a unified framework. Within this space, thermogenic output follows a hormetic, inverted-U trajectory within a Thermogenic Ferroptosis Window, reframing prior genetic, nutritional and pharmacological studies and guiding precision redox medicine.

Overall, this paper is very well written and clearly explains the subtleties of the TFW very well.

Comment 1: Section 2.3.2 does not flow smoothly. It doesn't seem to specify that it refers to Fig. 2.

Response: We are grateful for the positive assessment and for identifying this gap in flow. We agree that an explicit connection to the figure was missing. We have revised Section 2.3.2 to directly reference Figure 2 when introducing the Thermogenic Ferroptosis Window (TFW) and its failure modes, ensuring better cohesion between the text and the schematic. (Revised text: Lines 178-179)

Comment 2: "Compass" may not be the best word. Compass indicates direction, whereas the TFW is coordinates.

Response: We appreciate this thoughtful semantic point. While a compass implies directionality and the TFW represents coordinates, our use of "RTF-Compass" is metaphorical. It emphasizes the tool's function in guiding navigation—specifically, determining the therapeutic vectors (trajectories) required to move a depot from a pathological state into the optimal TFW. We have added a clarifying sentence in the Introduction to state that while the TFW defines the coordinate space, the "Compass" framework guides the directional interventions (vectors) needed for therapeutic success. (Revised text: Lines 33-35)

Reviewer 4 Report

Comments and Suggestions for Authors

Suggesting a coherent and innovative conceptual framework called RTF-compass is the strength of the current review article. This review does not merely collect and explain the previous knowledge found in earlier studies, but defines the RTF-compass as a new concept (model) determining the balance between thermogenesis and ferroptosis in brown adipocytes. By linking the complex interactions between redox, thermogenic potential, and ferroptotic stress, this model provides a navigational tool for understanding the initial and dynamic state of adipose tissue, which could aid in the development of more precise therapeutic strategies for obesity and increased thermogenesis in clinical settings.

The authors define a thermogenesis-ferroptosis window (TFW) and schematically illustrate its relationship with ferroptosis resistance capacity (FRC) and Ferroptosis signaling index (FSI). They also clearly explain how TFW can be widened or narrowed by therapeutic interventions. The authors also address hypoxia and HIF-α status (acute and transient/chronic and persistent) as a secondary yet important regulatory factor reshaping the accessibility and stability of TFW across time.

Furthermore, the authors have described the clinical applications of RTF-Compass through numerous examples and emphasized the necessity of dosing and timing of drug interventions, considering the initial state and the dynamic state of adipose tissue. Finally, they have stated the gaps in this topic and listed the prospects for future research.

However, there is an error in Figure 3, which should be corrected: The schematic adipocytes are potentially misleading, as the adipocyte in the adaptive state is depicted without mitochondria, whereas the maladaptive state shows mitochondrial presence. Since both states involve mitochondria, the distinction should reflect functional differences rather than organelle absence.

In summary, the article has a high degree of novelty, is well-structured, and provides new conceptual knowledge. Therefore, it could be accepted after correcting the mentioned error.

Author Response

Suggesting a coherent and innovative conceptual framework called RTF-compass is the strength of the current review article. This review does not merely collect and explain the previous knowledge found in earlier studies, but defines the RTF-compass as a new concept (model) determining the balance between thermogenesis and ferroptosis in brown adipocytes. By linking the complex interactions between redox, thermogenic potential, and ferroptotic stress, this model provides a navigational tool for understanding the initial and dynamic state of adipose tissue, which could aid in the development of more precise therapeutic strategies for obesity and increased thermogenesis in clinical settings.

The authors define a thermogenesis-ferroptosis window (TFW) and schematically illustrate its relationship with ferroptosis resistance capacity (FRC) and Ferroptosis signaling index (FSI). They also clearly explain how TFW can be widened or narrowed by therapeutic interventions. The authors also address hypoxia and HIF-α status (acute and transient/chronic and persistent) as a secondary yet important regulatory factor reshaping the accessibility and stability of TFW across time.

Furthermore, the authors have described the clinical applications of RTF-Compass through numerous examples and emphasized the necessity of dosing and timing of drug interventions, considering the initial state and the dynamic state of adipose tissue. Finally, they have stated the gaps in this topic and listed the prospects for future research.

However, there is an error in Figure 3, which should be corrected: The schematic adipocytes are potentially misleading, as the adipocyte in the adaptive state is depicted without mitochondria, whereas the maladaptive state shows mitochondrial presence. Since both states involve mitochondria, the distinction should reflect functional differences rather than organelle absence.

In summary, the article has a high degree of novelty, is well-structured, and provides new conceptual knowledge. Therefore, it could be accepted after correcting the mentioned error.

Comment 1: There is an error in Figure 3. The schematic adipocytes are potentially misleading, as the adipocyte in the adaptive state is depicted without mitochondria.

Response: We thank the reviewer for catching this visual inaccuracy. We agree that omitting mitochondria in the adaptive state could be misinterpreted as an absence of organelles rather than a functional difference. We have redrawn Figure 3 to show mitochondria in both adaptive and maladaptive states. The distinction is now conveyed through functional markers (e.g., robust UCP1-dependent uncoupling vs. suppressed oxidative capacity) and the surrounding hypoxic/redox context, rather than the presence or absence of the organelle itself. (Revised text: Lines 449-450)

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have responded to the suggestions correctly and have modified the manuscript considering the points requested.