Crym, encoding μ -crystallin, is an important gene with multiple functions. It codes for an intracellular high-affinity T3-binding protein that buffers cytosolic T3 availability, regulating thyroid hormone action [2]. It also acts as a ketimine reductase in the lysine degradation pathway [4]. The gene is associated with various biological processes and diseases, making genetic models crucial for its study.

In adult mice, CRISPR-Cas9-mediated knockout of Crym in striatal astrocytes led to perseverative behaviours, increased fast synaptic excitation in medium spiny neurons, and a disrupted excitatory-inhibitory synaptic balance. This showed that Crym-positive striatal astrocytes gate perseveration phenotypes related to neuropsychiatric disorders [1]. In murine models, ablation of the Crym gene caused hypertrophy of fast-twitch muscle fibers and an increase in fat mass in mice on a high-fat diet, indicating its role in muscle function and metabolism [4]. Liver-specific knockdown of Crym in adult mice abolished the protective effects of early-life exercise on anti-inflammatory immunity, suggesting its involvement in this immunometabolic process [3].

In conclusion, Crym is essential in multiple biological processes. Mouse models with Crym knockout or knockdown have revealed its roles in areas such as neuropsychiatric-related perseverative behaviours, muscle function and metabolism, and immunometabolic modulation. These findings contribute to understanding diseases associated with these processes, potentially guiding future therapeutic strategies.