Small regulatory polypeptide of amino acid response (SPAAR)

Small regulatory polypeptide of amino acid response (SPAAR) is a micropeptide (90 amino acids) encoded by the LINC00961 locus. Originally identified as a long non-coding RNA (LINC00961), this locus actually codes for both a functional RNA and the SPAAR micropeptide, conferring the locus dual biological functions[1][2]. SPAAR acts as a regulator of cell signaling by binding to and modulating proteins such as the v-ATPase complex at the lysosomal membrane, thereby inhibiting recruitment and activation of mTORC1 in response to amino acids[3][4]. In endothelial cells, SPAAR expression promotes angiogenic activities such as tubule formation, acting in opposition to the inhibitory effects of the LINC00961 RNA transcript[1][2]. SPAAR has also been implicated in muscle regeneration and actin cytoskeleton regulation through interaction with proteins such as SYNE1[1]. Expression of SPAAR is tissue- and context-dependent, found in lung, heart, and skeletal muscle, and pathophysiological studies in knockout mice confirm roles in post-injury muscle regeneration and angiogenesis[1][3]. Although not established as a direct therapeutic target (receptor, enzyme, etc.), SPAAR and its locus have emerging significance in vascular biology, regenerative medicine, and potentially in cancer, especially as lncRNA-encoded micropeptides and their regulation of key pathways like mTORC1 and endothelial function are further elucidated[1][2][4].

Other names

LINC00961SPARSmall regulatory polypeptide of amino acids responselong intergenic non-protein coding RNA 961