Mouse Anti Human DMPK Hybridoma [NBOEN7 8F5C8]

Serum response factor (SRF) transcriptionally regulates expression of contractile genes in smooth muscle cells (SMC). Lack or decrease of SRF is directly linked to a phenotypic change of SMC, leading to hypomotility of smooth muscle in the gastrointestinal (GI) tract. However, the molecular mechanism behind SRF-induced hypomotility in GI smooth muscle is largely unknown. We describe here how SRF plays a functional role in the regulation of the SMC contractility via myotonic dystrophy protein kinase (DMPK) and L-type calcium channel CACNA1C. GI SMC expressed Dmpk and Cacnalc genes into multiple alternative transcriptional isoforms. Deficiency of SRF in SMC of Srf knockout (KO) mice led to reduction of SRF-dependent DMPK, which down-regulated the expression of CACNA1C. Reduction of CACNA1C in KO SMC not only decreased intracellular Ca2+ spikes but also disrupted their coupling between cells resulting in decreased contractility. The role of SRF in the regulation of SMC phenotype and function provides new insight into how SMC lose their contractility leading to hypomotility in pathophysiological conditions within the GI tract.

Myotonic dystrophy type 1 (DM1) is a multisystemic disorder caused by trinucleotide CTG expansion in DMPK gene, often affecting the neighboring genes. Endocrine system is involved, resulting in hypogonadism and reproductive abnormalities, but molecular mechanisms underlying the reduced fertility observed in DM1 are very complex and partially unknown. To better characterize these mechanisms, an analysis of sperm parameters and anti-Mullerian hormone (AMH) values was performed in 20 DM1 patients. About 50% of them showed hypoposia and azoospermia; the remaining, despite an adequate volume of ejaculate, had oligo-astheno-teratozoospermia. Interestingly, the lowest AMH levels better correlated with the main sperm alterations. The pattern of expression of DMPK, SIX5, and RSPH6A genes, evaluated by quantitative reverse transcription polymerase chain reaction, showed a substantial reduction of the expression in both peripheral blood and in seminal plasma of patients, compared to controls. An impairment of testis-specific RSPH6A protein expression and localization was observed in sperm protein extracts by WB analysis and in isolated spermatozoa by immunofluorescence. These results support the hypothesis that CTG expansion also affects the expression of neighboring genes and contributes to gonad defects observed in DM1, suggesting the possibility of using them as markers for normal fertility in humans.