{'fraction_non_alphanumeric': 0.024832214765100672, 'fraction_numerical': 0.006711409395973154, 'mean_word_length': 5.686098654708521, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 1, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Activation of Vinculin Induced by Cholinergic Stimulation Regulates Tension Development in Tracheal Smooth Muscle (TSM)

The adhesion protein vinculin functions in focal adhesions to link actin filaments to membrane adhesion junctions by binding to the integrin‐binding protein talin at its head domain (Vh) and to actin filaments at its tail domain (Vt). In the inactive (closed) state, Vh and Vt bind to each other, masking the binding sites for actin and talin; in the active (open) state, vinculin binding sites for talin and actin are exposed. We hypothesized that the contractile activation of TSM might regulate conformation of vinculin and thereby contribute to the regulation of tension development. Stimulation of TSM tissues with acetylcholine (ACh) increased the co‐immunoprecipitation of vinculin and talin from tissue extracts, and increased vinculin phosphorylation at tyr 1065, an indicator of vinculin activation. Recombinant Vh (EGFP‐Vh) expressed in TSM tissues competed with endogenous vinculin for binding to talin and inhibited vinculin tyr 1065 phosphorylation. Expression of EGFP‐Vh depressed TSM contraction to ACh by 60% and inhibited ACh‐induced actin polymerization. EGFP‐Vh did not affect myosin light chain phosphorylation. We conclude that vinculin is activated in TSM by ACh, and that vinculin regulates tension by promoting connections between actin filaments and talin‐integrin adhesion complexes and by facilitating the initiation of actin polymerization.