Non-selective calcium permeant cation channel involved in osmotic sensitivity and mechanosensitivity (PubMed:16293632, PubMed:18695040, PubMed:18826956, PubMed:22526352, PubMed:23136043, PubMed:29899501). Activation by exposure to hypotonicity within the physiological range exhibits an outward rectification (PubMed:18695040, PubMed:18826956, PubMed:29899501). Also activated by heat, low pH, citrate and phorbol esters (PubMed:16293632, PubMed:18695040, PubMed:18826956, PubMed:20037586, PubMed:21964574, PubMed:25256292). Increase of intracellular Ca(2+) potentiates currents. Channel activity seems to be regulated by a calmodulin-dependent mechanism with a negative feedback mechanism (PubMed:12724311, PubMed:18826956). Promotes cell-cell junction formation in skin keratinocytes and plays an important role in the formation and/or maintenance of functional intercellular barriers (By similarity). Acts as a regulator of intracellular Ca(2+) in synoviocytes (PubMed:19759329). Plays an obligatory role as a molecular component in the nonselective cation channel activation induced by 4-alpha-phorbol 12,13-didecanoate and hypotonic stimulation in synoviocytes and also regulates production of IL-8 (PubMed:19759329). Together with PKD2, forms mechano- and thermosensitive channels in cilium (PubMed:18695040). Negatively regulates expression of PPARGC1A, UCP1, oxidative metabolism and respiration in adipocytes (By similarity). Regulates expression of chemokines and cytokines related to pro-inflammatory pathway in adipocytes (By similarity). Together with AQP5, controls regulatory volume decrease in salivary epithelial cells (By similarity). Required for normal development and maintenance of bone and cartilage (PubMed:26249260). In its inactive state, may sequester DDX3X at the plasma membrane. When activated, the interaction between both proteins is affected and DDX3X relocalizes to the nucleus (PubMed:29899501). In neurons of the central nervous system, could play a role in triggering voluntary water intake in response to increased sodium concentration in body fluid (By similarity). {ECO:0000250|UniProtKB:Q9EPK8, ECO:0000269|PubMed:11025659, ECO:0000269|PubMed:12724311, ECO:0000269|PubMed:16293632, ECO:0000269|PubMed:18587396, ECO:0000269|PubMed:18695040, ECO:0000269|PubMed:18826956, ECO:0000269|PubMed:19759329, ECO:0000269|PubMed:20037586, ECO:0000269|PubMed:21964574, ECO:0000269|PubMed:23136043, ECO:0000269|PubMed:25256292, ECO:0000269|PubMed:26249260, ECO:0000269|PubMed:29899501}. [Isoform 1]: Non-selective calcium permeant cation channel involved in osmotic sensitivity and mechanosensitivity. Activation by exposure to hypotonicity within the physiological range exhibits an outward rectification. Also activated by phorbol esters. Has the same channel activity as isoform 1, and is activated by the same stimuli. . [Isoform 5]: Non-selective calcium permeant cation channel involved in osmotic sensitivity and mechanosensitivity. Activation by exposure to hypotonicity within the physiological range exhibits an outward rectification. Also activated by phorbol esters. Has the same channel activity as isoform 1, and is activated by the same stimuli. . [Isoform 2]: Lacks channel activity, due to impaired oligomerization and intracellular retention. . [Isoform 4]: Lacks channel activity, due to impaired oligomerization and intracellular retention. . [Isoform 6]: Lacks channel activity, due to impaired oligomerization and intracellular retention. . (Microbial infection) Facilitates hepatitis C virus (HCV) replication, possibly through its action on DDX3X. . (Microbial infection) Facilitates Dengue virus (DENV) replication, possibly through its action on DDX3X. . (Microbial infection) Facilitates Zika virus (ZIKV) replication, possibly through its action on DDX3X. . This is the function of TRPV4 (transient receptor potential cation channel subfamily V member 4, ENSG00000111199).