Janine Sengstack

New study: for years Yamanaka factors have driven longevity optimism. They factory reset cellular age, also erase the cellular identity. The drawback is potential cancer. Transcription Factor Perturbations is a new scalpel approach targeting specific rejuvenation levers while keeping the cell's identity. Example breakthrough EZH2: mouse liver age reversal by 8 human-year equivalent by reducing liver fibrosis and fat by 50% and significantly improving glucose tolerance. Study details Transcriptional factors, particularly the Yamanaka factors (OSKM), are key to understanding and potentially reversing aging. OSKM can perform a cellular "factory reset," erasing epigenetic memory and inducing a stem cell-like state. Partial reprogramming with OSKM offers a path to rejuvenation, but its clinical use requires precise temporal and dosage control to prevent dedifferentiation and tumor formation. A recent study established a Transcriptional Rejuvenation Discovery Platform (TRDP) to identify novel transcription factor perturbations capable of driving cellular rejuvenation and reversing aspects of replicative aging in human fibroblasts. The platform was trained on transcriptional shifts between early- and late-passage human cells in culture to identify gene expression and transcription factor changes associated with aging. These changes were ranked computationally to prioritize transcription factors relevant to rejuvenation. The top 200 candidates were screened by parallel overexpression (CRISPRa) or inhibition (CRISPRi), followed by single-cell RNA sequencing to evaluate transcriptional consequences. Rejuvenating factors were identified by their ability to reverse aging-associated gene expression, quantified by a negative correlation score (R₍rej₎). Four were selected for further study: inhibition of STAT3 and ZFX, and activation of EZH2 and E2F3. Findings in human cells (fibroblasts in cell culture) In high-passage cells, all four perturbations induced rejuvenation-associated phenotypes, including increased proliferation (KI67), improved proteasome activity, reduced lysosomal staining, p21 downregulation, and improved mitochondrial function (strongest with EZH2). These effects mirrored in vitro OSKM reprogramming for the measured hallmarks, but without changing cellular identity. DNA methylation clocks remained stable, consistent with the decoupling of senescence and epigenetic aging. Findings in aging mouse livers For in vivo validation, the aging mouse liver was chosen. EZH2 was selected due to its age-associated decline, favorable safety profile over E2F3, and lack of STAT3-like disease-specific liver involvement. Three weeks of liver-specific EZH2 overexpression via AAV8 delivery reversed aging-associated gene expression and phenotypes by an equivalent of roughly eight months of mouse aging, including reductions in steatosis and fibrosis and improvements in glucose tolerance. EZH2 overexpression produced stronger rejuvenation-associated transcriptional changes in vivo than those observed in vitro, particularly affecting inflammatory pathways and age-related loss of cellular identity, including inappropriate activation of muscle and cardiac gene programs in aged liver tissue. In 20-month-old mice, fibrosis and glucose intolerance improved by approximately 50% relative to young mice. Importantly, cellular identity was preserved, no liver damage or histological abnormalities were observed, and comparisons with multiple mouse liver cancer models showed no overlap with cancer-associated transcriptional signatures over the short treatment window. Significance This work introduces a systematic framework for identifying transcriptional factors as potential levers for longevity and rejuvenation. EZH2 emerges as a promising target for further exploration via gene therapy or targeted modulators, based on rejuvenation-associated signatures observed in human fibroblasts and functional rejuvenation of the aging mouse liver without overt damage or cancer-like signals. While the OSKM reprogramming strategy demonstrate the reversibility of aging through global epigenetic resetting, it carries intrinsic risks related to identity destabilization. In contrast, targeted transcription factor perturbations enable the reversal of multiple aging-associated hallmarks without engaging in full or partial reprogramming, suggesting a more precise and potentially safer route to rejuvenation. These distinct approaches collectively indicate that rejuvenation operates across various biological layers, from broad epigenetic resets to targeted transcriptional network recalibration. Limitations The current screening strategy and computational model are biased towards transcription factors effective in replicative aging models of passaged neonatal human dermal fibroblasts, which differ substantially from organismal aging in vivo. While many hallmarks overlap, this model does not fully capture aging in post-mitotic cells or complex tissue and organ environments. The platform uses cellular proliferation and survival in culture as proxies for rejuvenation, whereas in vivo aging is influenced by additional factors such as differentiation state, immune interactions, and intercellular communication. Reliance on proliferative capacity also carries inherent oncogenic risk. Although cancer-associated transcriptional signatures were not observed in this study, longer-term effects cannot be excluded. Finally, liver rejuvenation was demonstrated in a single organ over a short treatment period in mice. The absence of damage or oncogenic signatures cannot be considered a definitive safety signal, and long-term studies, including large-animal and non-human primate models, will be required to establish safety, durability, and systemic relevance.

New study: for years Yamanaka factors have driven longevity optimism. They factory reset cellular age, also erase the cellular identity. The drawback is potential cancer. Transcription Factor Perturbations is a new scalpel approach targeting specific rejuvenation levers while keeping the cell's identity. Example breakthrough EZH2: mouse liver age reversal by 8 human-year equivalent by reducing liver fibrosis and fat by 50% and significantly improving glucose tolerance. Study details Transcriptional factors, particularly the Yamanaka factors (OSKM), are key to understanding and potentially reversing aging. OSKM can perform a cellular "factory reset," erasing epigenetic memory and inducing a stem cell-like state. Partial reprogramming with OSKM offers a path to rejuvenation, but its clinical use requires precise temporal and dosage control to prevent dedifferentiation and tumor formation. A recent study established a Transcriptional Rejuvenation Discovery Platform (TRDP) to identify novel transcription factor perturbations capable of driving cellular rejuvenation and reversing aspects of replicative aging in human fibroblasts. The platform was trained on transcriptional shifts between early- and late-passage human cells in culture to identify gene expression and transcription factor changes associated with aging. These changes were ranked computationally to prioritize transcription factors relevant to rejuvenation. The top 200 candidates were screened by parallel overexpression (CRISPRa) or inhibition (CRISPRi), followed by single-cell RNA sequencing to evaluate transcriptional consequences. Rejuvenating factors were identified by their ability to reverse aging-associated gene expression, quantified by a negative correlation score (R₍rej₎). Four were selected for further study: inhibition of STAT3 and ZFX, and activation of EZH2 and E2F3. Findings in human cells (fibroblasts in cell culture) In high-passage cells, all four perturbations induced rejuvenation-associated phenotypes, including increased proliferation (KI67), improved proteasome activity, reduced lysosomal staining, p21 downregulation, and improved mitochondrial function (strongest with EZH2). These effects mirrored in vitro OSKM reprogramming for the measured hallmarks, but without changing cellular identity. DNA methylation clocks remained stable, consistent with the decoupling of senescence and epigenetic aging. Findings in aging mouse livers For in vivo validation, the aging mouse liver was chosen. EZH2 was selected due to its age-associated decline, favorable safety profile over E2F3, and lack of STAT3-like disease-specific liver involvement. Three weeks of liver-specific EZH2 overexpression via AAV8 delivery reversed aging-associated gene expression and phenotypes by an equivalent of roughly eight months of mouse aging, including reductions in steatosis and fibrosis and improvements in glucose tolerance. EZH2 overexpression produced stronger rejuvenation-associated transcriptional changes in vivo than those observed in vitro, particularly affecting inflammatory pathways and age-related loss of cellular identity, including inappropriate activation of muscle and cardiac gene programs in aged liver tissue. In 20-month-old mice, fibrosis and glucose intolerance improved by approximately 50% relative to young mice. Importantly, cellular identity was preserved, no liver damage or histological abnormalities were observed, and comparisons with multiple mouse liver cancer models showed no overlap with cancer-associated transcriptional signatures over the short treatment window. Significance This work introduces a systematic framework for identifying transcriptional factors as potential levers for longevity and rejuvenation. EZH2 emerges as a promising target for further exploration via gene therapy or targeted modulators, based on rejuvenation-associated signatures observed in human fibroblasts and functional rejuvenation of the aging mouse liver without overt damage or cancer-like signals. While the OSKM reprogramming strategy demonstrate the reversibility of aging through global epigenetic resetting, it carries intrinsic risks related to identity destabilization. In contrast, targeted transcription factor perturbations enable the reversal of multiple aging-associated hallmarks without engaging in full or partial reprogramming, suggesting a more precise and potentially safer route to rejuvenation. These distinct approaches collectively indicate that rejuvenation operates across various biological layers, from broad epigenetic resets to targeted transcriptional network recalibration. Limitations The current screening strategy and computational model are biased towards transcription factors effective in replicative aging models of passaged neonatal human dermal fibroblasts, which differ substantially from organismal aging in vivo. While many hallmarks overlap, this model does not fully capture aging in post-mitotic cells or complex tissue and organ environments. The platform uses cellular proliferation and survival in culture as proxies for rejuvenation, whereas in vivo aging is influenced by additional factors such as differentiation state, immune interactions, and intercellular communication. Reliance on proliferative capacity also carries inherent oncogenic risk. Although cancer-associated transcriptional signatures were not observed in this study, longer-term effects cannot be excluded. Finally, liver rejuvenation was demonstrated in a single organ over a short treatment period in mice. The absence of damage or oncogenic signatures cannot be considered a definitive safety signal, and long-term studies, including large-animal and non-human primate models, will be required to establish safety, durability, and systemic relevance.