{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nRecent advances in neural development illustrate that highly regulated signaling cascades govern key aspects of axonal remodeling. For instance, during postnatal hippocampal development the chemorepellent Sema3F signals via neuropilin-2 to engage β2‑chimaerin, a Rac1‐specific GTPase‐activating protein, which in turn modulates Rac1‐dependent cytoskeletal reorganization essential for selective axon pruning and synapse elimination. This signaling cascade facilitates proper neural connectivity and plasticity, delineating a pathway distinct from that controlling axon repulsion or dendritic spine remodeling."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nAdditional mechanistic insight has been obtained regarding the regulation of β2‑chimaerin itself. In response to epidermal growth factor stimulation or phorbol ester treatment, rapid phosphorylation of β2‑chimaerin on Ser169 occurs via protein kinase Cδ. This modification retains the chimaerin in the cytosol by inhibiting its C1 domain–mediated membrane translocation, thus tempering Rac1 inactivation and affecting downstream cell migratory behavior."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "2"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn a seemingly distinct cellular context, transient exposure to mild oxidative stress in human osteosarcoma cells induces an adaptive response characterized by increased levels of intracellular glutathione. This adaptive response is accompanied by the up-regulation of the AROS‑29 gene, which encodes a transmembrane protein of hitherto unknown function. Overexpression of AROS‑29 enhances cellular resistance to subsequent oxidative challenges by mitigating DNA damage and apoptosis. Although not directly named TMEM161A in these studies, the attributes of AROS‑29 suggest that related transmembrane proteins—such as TMEM161A—might exert analogous protective roles in cellular homeostasis under stress conditions."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn the realm of tumor biology, β2‑chimaerin emerges as a dual‐function tumor suppressor in breast cancer. Its expression in epithelial cells leads to reduced E‑cadherin levels, weakening cell–cell adhesion and potentially influencing tumor progression. In vivo genetic ablation of β2‑chimaerin in a mouse model accelerates tumor onset, even as it delays tumor progression, underscoring a complex role in modulating oncogenic processes. This inverse relationship between chimaerin and E‑cadherin expression has also been observed in Her2⁺ breast tumors and correlates with patient relapse-free survival outcomes."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nFurthermore, α2‑chimaerin has been shown to be crucial for maintaining homeostasis within the adult hippocampal neurogenic niche. Conditional deletion of α2‑chimaerin in neural stem cells precipitates premature differentiation into intermediate progenitors, thereby depleting the stem cell pool and impairing neurogenesis. These cellular alterations culminate in deficits in hippocampal synaptic plasticity and the emergence of anxiety/depression-like behaviors, highlighting its indispensable role in adult brain function."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Martin M Riccomagno, Andrés Hurtado, HongBin Wang, et al. "}, {"type": "b", "children": [{"type": "t", "text": "The RacGAP β2-Chimaerin selectively mediates axonal pruning in the hippocampus."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Cell (2012)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.cell.2012.05.018"}], "href": "https://doi.org/10.1016/j.cell.2012.05.018"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "22726444"}], "href": "https://pubmed.ncbi.nlm.nih.gov/22726444"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Erin M Griner, M Cecilia Caino, Maria Soledad Sosa, et al. "}, {"type": "b", "children": [{"type": "t", "text": "A novel cross-talk in diacylglycerol signaling: the Rac-GAP beta2-chimaerin is negatively regulated by protein kinase Cdelta-mediated phosphorylation."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2010)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M109.099036"}], "href": "https://doi.org/10.1074/jbc.M109.099036"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "20335173"}], "href": "https://pubmed.ncbi.nlm.nih.gov/20335173"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "Nicola Montesano Gesualdi, Giuseppa Chirico, Maria Teresa Catanese, et al. "}, {"type": "b", "children": [{"type": "t", "text": "AROS-29 is involved in adaptive response to oxidative stress."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Free Radic Res (2006)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1080/10715760600570547"}], "href": "https://doi.org/10.1080/10715760600570547"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "16551573"}], "href": "https://pubmed.ncbi.nlm.nih.gov/16551573"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Victoria Casado-Medrano, Laura Barrio-Real, Ginesa García-Rostán, et al. "}, {"type": "b", "children": [{"type": "t", "text": "A new role of the Rac-GAP β2-chimaerin in cell adhesion reveals opposite functions in breast cancer initiation and tumor progression."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Oncotarget (2016)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.18632/oncotarget.8597"}], "href": "https://doi.org/10.18632/oncotarget.8597"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "27058424"}], "href": "https://pubmed.ncbi.nlm.nih.gov/27058424"}]}, {"type": "r", "ref": 5, "children": [{"type": "t", "text": "Yi-Ting Su, Shun-Fat Lau, Jacque P K Ip, et al. "}, {"type": "b", "children": [{"type": "t", "text": "α2-Chimaerin is essential for neural stem cell homeostasis in mouse adult neurogenesis."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Proc Natl Acad Sci U S A (2019)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1073/pnas.1903891116"}], "href": "https://doi.org/10.1073/pnas.1903891116"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "31209021"}], "href": "https://pubmed.ncbi.nlm.nih.gov/31209021"}]}]}]}