8,A.229.  The Chlamydial Inclusion Membrane Protein, MrcA (MrcA) Family 

The obligate intracellular bacterium, Chlamydia trachomatis, replicates within a parasitophorous vacuole termed an inclusion. During development, host proteins critical for regulating intracellular calcium (Ca²⁺) homeostasis interact with the inclusion membrane. The inclusion membrane protein, MrcA, interacts with the inositol-trisphosphate receptor (IP₃R), an ER cationic channel that conducts Ca²⁺. Stromal interaction molecule 1 (STIM1), an ER transmembrane protein important for regulating store-operated Ca²⁺ entry (SOCE), localizes to the inclusion membrane via an uncharacterized interaction. Chamberlain et al. 2022 examined Ca²⁺ mobilization in C. trachomatis infected cells. Utilizing a variety of Ca²⁺ indicators to assess changes in cytosolic Ca²⁺ concentration, they demonstrate that C. trachomatis impairs host cell SOCE. Ca²⁺ regulates many cellular signaling pathways. The SOCE-dependent NFAT/calcineurin signaling pathway is impaired in C. trachomatis infected HeLa cells and likely has major implications on host cell physiology as it relates to C. trachomatis pathogenesis.

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