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by claude@2026-06, 2026-06-24
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The paper investigates how perineuronal nets (PNNs) form early in Rett syndrome by studying Mecp2-null neocortex, with a focus on whether precocious PNN formation is driven by astrocytes and associated ECM regulators. Using astrocyte-conditioned media and developmental analyses, the authors report that Mecp2-null astrocyte conditioned media induces Hapln1 expression and increases PNN formation on wildtype neurons, indicating a non–cell-autonomous contribution from astrocytes; they also find elevated HAPLN1 and other PNN/ECM components in developing Mecp2-null cortex with PNNs maturing structurally and biochemically earlier than normal. A key limitation is that the work is primarily mechanistic and developmental within the Mecp2-null mouse model, without direct demonstration of downstream functional behavioral rescue in the described experiments. This paper does not explicitly discuss endometriosis or adenomyosis; it was included in the corpus via a keyword match in the upstream search index.
Abstract
Rett syndrome (RTT), caused by mutations in MECP2 , is a complex neurological disorder characterized by myriad physiological disruptions, including early closure of the critical period of developmental plasticity and precocious formation of perineuronal nets (PNNs). PNNs are lattice-like substructures of extracellular matrix (ECM) that enwrap specific subpopulations of neurons. PNNs are essential in the modulation of neuronal plasticity and brain maturation, and their enzymatic disruption can partially restore plasticity in adults and improve memory. Although precocious PNN formation is well-established in RTT, little is known of the cellular, molecular, or biochemical underpinnings of their precocious formation, or whether precocious PNN formation is due to cell-autonomous or non-cell-autonomous mechanisms. While PNNs form on subsets of neurons throughout the brain, astrocytes secrete many ECM components that form PNNs, and they play a central role in controlling closure of the critical period. We find that Mecp2 -null astrocyte conditioned media induces the expression of the key PNN component Hapln1 and causes enhanced PNN formation on wildtype neurons, suggesting that Mecp2 -null astrocytes play a key role in the precocious formation of PNNs in RTT. Further, we identify increased expression of HAPLN1 and other PNN / ECM components in the developing Mecp2 -null cortex, and demonstrate that PNNs are structurally and biochemically mature at an earlier developmental stage. These results provide essential insight into the mechanisms and structure of aberrant PNNs in Mecp2 -null cortex and identify potential new avenues for targeted rescue or reversal of the precocious closing of the critical period in RTT.
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Abstract
Rett syndrome (RTT), caused by mutations in MECP2, is a complex neurological disorder characterized by myriad physiological disruptions, including early closure of the critical period of developmental plasticity and precocious formation of perineuronal nets (PNNs). PNNs are lattice-like substructures of extracellular matrix (ECM) that enwrap specific subpopulations of neurons. PNNs are essential in the modulation of neuronal plasticity and brain maturation, and their enzymatic disruption can partially restore plasticity in adults and improve memory. Although precocious PNN formation is well-established in RTT, little is known of the cellular, molecular, or biochemical underpinnings of their precocious formation, or whether precocious PNN formation is due to cell-autonomous or non-cell-autonomous mechanisms. While PNNs form on subsets of neurons throughout the brain, astrocytes secrete many ECM components that form PNNs, and they play a central role in controlling closure of the critical period. We find that Mecp2-null astrocyte conditioned media induces the expression of the key PNN component Hapln1 and causes enhanced PNN formation on wildtype neurons, suggesting that Mecp2-null astrocytes play a key role in the precocious formation of PNNs in RTT. Further, we identify increased expression of HAPLN1 and other PNN / ECM components in the developing Mecp2-null cortex, and demonstrate that PNNs are structurally and biochemically mature at an earlier developmental stage. These results provide essential insight into the mechanisms and structure of aberrant PNNs in Mecp2-null cortex and identify potential new avenues for targeted rescue or reversal of the precocious closing of the critical period in RTT.
Competing Interest Statement
The authors have declared no competing interest.
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